CN109787494B - A voltage switching circuit and dual energy CT - Google Patents

Abstract

The embodiment of the invention discloses a voltage switching circuit and a dual-energy CT. The voltage switching circuit includes: the first switching output end, the second switching output end and the rectifying and filtering module are connected between the first switching output end and the second switching output end; the rectification filter module comprises a filter unit connected to the output end of the rectification filter module, the voltage of the output end of the rectification filter module is a first voltage, the capacitance value of the filter unit is set as a first capacitance value, the voltage of the output end of the rectification filter module is a second voltage, and the capacitance value of the filter unit is set as a second capacitance value; the first voltage is greater than the second voltage, and the first capacitance is less than the second capacitance. Compared with the prior art, the embodiment of the invention realizes the effects of improving the voltage switching speed, reducing the cost and having a large applicable load current range.

Description

A voltage switching circuit and dual energy CT

technical field

The embodiments of the present invention relate to the technical field of electronic circuits, and in particular, to a voltage switching circuit and a dual-energy CT.

Background technique

Computed tomography (Computed Tomography, CT) is widely used in medical inspection, industrial inspection and security inspection and other inspection fields. With the development of technological level and computer technology, CT has also developed rapidly. In order to obtain more accurate detection results, dual-energy CT came into being.

The working principle of dual-energy CT is that the inverter, high-voltage transformer, and rectifier and filter modules form a high-voltage generator, and the output voltage of the high-voltage generator changes rapidly between two voltage levels (for example, the low voltage level is 80kV, and the high voltage level 140kV), the bulb is used as an X-ray generating source to emit two X-rays with different energy levels at these two voltage levels, respectively, and the X-ray detector can obtain dual-energy data accordingly. And, the shorter the switching time between the two voltage levels, the more conducive to the separation of dual-energy data; on the contrary, the longer the switching time between the two voltage levels, the greater the dose of ineffective X-rays emitted, the CT turns one The smaller the number of valid views for the circle. Therefore, shorter voltage switching time has become the development trend of high-voltage generators for dual-energy CT. Among them, the switching of the voltage level includes the high-voltage working mode and the low-voltage working mode. In the process of switching from the low-voltage working mode to the high-voltage working mode, the current stress of the inverter may be much greater than that of the high-voltage generator in the steady state output. Inverter current stress, so the requirement for inverter's short-term high power output capability is high; in the process of switching from high-voltage working mode to low-voltage working mode, the energy in the filter capacitor mainly depends on the tube current of the tube The energy is taken away, so the switching time is relatively short when the large current is output, and the switching time is relatively long when the small current is output.

In the prior art, inverters with better short-term high current stress are often used and output filter capacitors with smaller capacitance values are used. This solution can shorten the switching time, however, it will increase the cost of the inverter, and the high voltage The generator's fall time improvement at small currents is not good. Therefore, the prior art has the problems of slow voltage switching speed and high cost.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a voltage switching circuit and a dual-energy CT, so as to achieve the purpose of increasing the voltage switching speed and reducing the cost.

In a first aspect, an embodiment of the present invention provides a voltage switching circuit, the voltage switching circuit includes: a first switching output terminal and a second switching output terminal, and is connected to the first switching output terminal and the second switching output terminal Rectification filter module between the output terminals;

The rectification filter module includes a filter unit connected to its output, the output voltage of the rectifier filter module is the first voltage, the capacitance value of the filter unit is set to the first capacitance value, and the rectifier filter module has a first capacitance value. The output terminal voltage is a second voltage, and the capacitance value of the filtering unit is set as the second capacitance value; the first voltage is greater than the second voltage, and the first capacitance value is smaller than the second capacitance value.

Optionally, the output end of the rectification filter module includes a first output end and a second output end;

The filtering unit includes a first filtering unit and a second filtering unit, the first end of the first filtering unit is electrically connected to the first output end of the rectification filtering module, and the second end of the second filtering unit is electrically connected to the first output end of the rectification filtering module. the second output end of the rectification filter module is electrically connected;

The rectification filter module includes:

A first rectifier unit, the first input end of the first rectifier unit is used as the first input end of the rectifier filter module, and the second input end of the first rectifier unit is used as the second input end of the rectifier filter module , the first output end of the first rectifier unit is electrically connected to the first output end of the rectifier filter module, and the second output end of the first rectifier unit is electrically connected to the second output end of the rectifier filter module ;

The first filter switching unit includes a first end, a second end, a third end and a fourth end; the first end of the first filter switching unit is electrically connected to the first output end of the rectification filter module, the The second end of the first filter switching unit is electrically connected to the second end of the first filter unit, the third end of the first filter switch unit is electrically connected to the first end of the second filter unit, and the The fourth terminal of the first filter switching unit is electrically connected to the second output terminal of the rectification filter module; the first filter switch unit is used to set the output terminal voltage of the rectification filter module to the first voltage The first filter unit and the second filter unit are connected in series, and when the output terminal voltage of the rectification filter module is the second voltage, the first filter unit and the second filter unit are set in parallel.

Optionally, the first filter switching unit includes:

a first transistor, the first terminal of the first transistor is electrically connected to the first terminal of the first filter switching unit, and the second terminal of the first transistor is electrically connected to the third terminal of the first filter switching unit connect;

a second transistor, the first end of the second transistor is electrically connected to the third end of the first filter switching unit, and the second end of the second transistor is electrically connected to the second end of the first filter switching unit connect;

A third transistor, the first end of the third transistor is electrically connected to the first end of the first filter switching unit, and the second end of the third transistor is electrically connected to the fourth end of the first filter switching unit connect;

The cathode of the body diode of the transistor serves as the first end of the transistor; the anode of the body diode of the transistor serves as the second end of the transistor.

Optionally, the first transistor, the second transistor and the third transistor are MOSFETs or IGBTs.

Optionally, the first filter switching unit includes:

a first diode, the cathode of the first diode is electrically connected to the first end of the first filter switching unit, and the anode of the first diode is electrically connected to the third terminal of the first filter switching unit terminal electrical connection;

a fourth transistor, the first end of the fourth transistor is electrically connected to the third end of the first filter switching unit, and the second end of the fourth transistor is electrically connected to the second end of the first filter switching unit connect;

a fifth transistor, the first end of the fifth transistor is electrically connected to the first end of the first filter switching unit, and the second end of the fifth transistor is electrically connected to the fourth end of the first filter switching unit connect;

The cathode of the body diode of the transistor serves as the first end of the transistor; the anode of the body diode of the transistor serves as the second end of the transistor.

Optionally, the first rectifier unit is: a full-bridge rectifier circuit, a voltage doubling rectifier circuit or a CW circuit.

Optionally, the rectification filter module is a first rectification filter module;

The voltage switching circuit further includes:

the first inverter;

a first transformer, the primary side winding of the first transformer is electrically connected to the output end of the first inverter; the input end of the first rectification filter module is electrically connected to the secondary side winding of the first transformer ; the first output end of the first rectification filter module is electrically connected to the first switching output end;

the second inverter;

a second transformer, the primary side winding of the second transformer is electrically connected to the output end of the second transformer;

A second rectifying and filtering module, the input end of the second rectifying and filtering module is electrically connected to the secondary winding of the second transformer; the first output end of the second rectifying and filtering module is connected to the first rectifying and filtering module The second output end of the second rectifier and filter module is electrically connected to the second output end of the second switch.

Optionally, the output voltage of the first switching output terminal and the second switching output terminal is a first voltage kV_h or a second voltage kV_1;

The output voltage of the first rectification filter module is kV_h-kV_1 or 2 (kV_h-kV_1);

The output voltage of the second rectification filter module is 2kV_1-kV_h.

Optionally, the output end of the rectification filter module includes a first output end and a second output end;

The filtering unit includes a third filtering unit and a fourth filtering unit, the first end of the third filtering unit is electrically connected to the first output end of the rectification filtering module, and the second end of the fourth filtering unit is electrically connected to the first output end of the rectification filtering module. the second output end of the rectification filter module is electrically connected;

The rectification filter module includes:

The second rectifier unit, the first input end of the second rectifier unit is used as the first input end of the rectifier filter module, and the second input end of the second rectifier unit is used as the second input end of the rectifier filter module , the first output end of the second rectifier unit is electrically connected to the first output end of the rectifier filter module, and the second output end of the second rectifier unit is electrically connected to the second output end of the rectifier filter module The second rectifier unit is used to set the second rectifier unit as the first topology structure when the output terminal voltage of the rectifier filter module is the first voltage, and the output terminal voltage of the rectifier filter module is When the second voltage is used, the second rectifier unit is set as the second topology structure;

The second filter switching unit includes a first end, a second end, a third end, a fourth end and a fifth end; the first end of the second filter switching unit is electrically connected to the first output end of the rectification filter module connected, the second end of the second filter switching unit is electrically connected to the second end of the third filter unit, and the third end of the second filter switching unit is electrically connected to the second input end of the rectification filter module connected, the fourth end of the second filter switching unit is electrically connected to the first end of the fourth filter unit, and the fifth end of the second filter switching unit is electrically connected to the second output end of the rectification filter module connection; the second filter switching unit is used to set the capacitance value of the filter unit to the capacitance value of the third filter unit or the first voltage when the output voltage of the rectifier filter module is the first voltage. For the capacitance values of the four filter units, when the output terminal voltage of the rectification filter module is the second voltage, the third filter unit and the fourth filter unit are set in parallel.

Optionally, the second rectifier unit includes:

A second diode, the anode of the second diode is electrically connected to the first input end of the second rectifier unit, and the cathode of the second diode is electrically connected to the first output of the second rectifier unit terminal electrical connection;

a third diode, the anode of the third diode is electrically connected to the second output terminal of the second rectifying unit, and the cathode of the third diode is electrically connected to the first input of the second rectifying unit terminal electrical connection;

a fourth diode, the cathode of the fourth diode is electrically connected to the first output end of the second rectifying unit;

a sixth transistor, the first end of the sixth transistor is electrically connected to the second input end of the second rectifier unit, and the second end of the sixth transistor is electrically connected to the anode of the fourth diode;

a seventh transistor, the second end of the seventh transistor is electrically connected to the second input end of the second rectifying unit;

a fifth diode, the anode of the fifth diode is electrically connected to the second output terminal of the second rectifier unit, and the cathode of the fifth diode is electrically connected to the first terminal of the seventh transistor connect;

The cathode of the body diode of the transistor serves as the first end of the transistor; the anode of the body diode of the transistor serves as the second end of the transistor.

Optionally, the second filter switching unit includes:

an eighth transistor, the first end of the eighth transistor is electrically connected to the third end of the second filter switching unit, and the second end of the eighth transistor is electrically connected to the second end of the second filter switching unit connect;

a ninth transistor, the first end of the ninth transistor is electrically connected to the fourth end of the second filter switching unit, and the second end of the ninth transistor is electrically connected to the third end of the second filter switching unit connect;

A tenth transistor, the first end of the tenth transistor is electrically connected to the first end of the second filter switching unit, and the second end of the tenth transistor is electrically connected to the fourth end of the second filter switching unit connect;

An eleventh transistor, the first end of the eleventh transistor is electrically connected to the second end of the second filter switching unit, and the second end of the eleventh transistor is electrically connected to the first end of the second filter switching unit Five-terminal electrical connection;

The cathode of the body diode of the transistor serves as the first end of the transistor; the anode of the body diode of the transistor serves as the second end of the transistor.

Optionally, the rectification filter module is a third rectification filter module;

The voltage switching circuit further includes:

the third inverter;

a third transformer, the primary side winding of the third transformer is electrically connected to the output end of the third inverter; the third transformer includes a first secondary side winding and a second secondary side winding; the third The first input end of the three rectifier filter module is electrically connected to the first end of the first secondary side winding; the second input end of the third rectifier filter module is electrically connected to the second end of the first secondary side winding electrical connection; the first output end of the third rectification filter module is electrically connected to the first switching output end;

a fourth rectifying and filtering module, the first input end of the fourth rectifying and filtering module is electrically connected with the first end of the second secondary side winding; the second input end of the fourth rectifying and filtering module is connected with the first end of the second secondary winding The second end of the secondary winding is electrically connected; the first output end of the fourth rectifier and filter module is electrically connected to the second output end of the third rectifier and filter module; the second end of the fourth rectifier and filter module is electrically connected. The output terminal is electrically connected to the second switching output terminal.

Optionally, the output voltage of the first switching output terminal and the second switching output terminal is a first voltage kV_h or a second voltage kV_1;

The output voltage of the third rectification filter module is kV_h-kV_1 or 2 (kV_h-kV_1);

The output voltage of the fourth rectification filter module is 2kV_1-kV_h.

Optionally, it also includes: the number of the rectification filter modules is N;

Wherein, the first output terminal of the first rectifier and filter module is electrically connected to the first switching output terminal, and the fourth terminal of the i-th rectifier and filter module is electrically connected to the i+1-th rectifier and filter module. The first output terminal is electrically connected, and the fourth terminal of the Nth rectifying filter module is electrically connected to the second switching output terminal; N≥1, 1≤i<N.

Optionally, the voltage switching circuit further includes: a control system, the control system is connected to the voltage switching circuit, and is used for controlling the voltage of the voltage output terminal of the voltage switching circuit.

In a second aspect, an embodiment of the present invention further provides a dual-energy CT, where the dual-energy CT includes: a voltage switching circuit and a bulb according to any embodiment of the present invention;

The power supply end of the bulb is electrically connected to the voltage output end of the voltage switching circuit, and the high voltage generator is used for supplying power to the bulb.

In the embodiment of the present invention, by switching the capacitance value of the filter unit of the rectification filter module, the capacitance value of the filter unit is set to the first capacitance value, and the output terminal voltage of the rectifier filter module is the first voltage; the capacitance value of the filter unit is set to the first capacitance value. It is set as the second capacitance value, and the output voltage of the rectification filter module is the second voltage; and the voltage of the filter unit is negatively correlated with the capacitance value, which is beneficial to the switching process of the output two voltage levels. The amount is almost unchanged, that is, it is beneficial to reduce the charging and discharging time of the filter unit. Compared with the prior art, in the process of switching between two output voltage levels in the embodiment of the present invention, the change of the charge amount of the filter unit is small, so it is not necessary to charge and discharge the filter unit for a long time. On the one hand, the voltage switching is improved. speed, and the voltage switching speed is not affected by load current changes, on the other hand, there is no need to use an inverter with better current stress. Therefore, the embodiments of the present invention achieve the effects of increasing the voltage switching speed, reducing the cost, and widening the applicable load current range.

Description of drawings

1 is a schematic diagram of a circuit structure of a voltage switching circuit according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a working mode of the voltage switching circuit in FIG. 1;

3 is a schematic structural diagram of another operating mode of the voltage switching circuit in FIG. 1;

4 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention;

5 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention;

6 is a schematic structural diagram of a working mode of the voltage switching circuit in FIG. 5;

7 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention;

8 is a schematic waveform diagram of an output voltage of a voltage switching circuit according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a working mode of the voltage switching circuit in FIG. 9;

FIG. 11 is a schematic structural diagram of another working mode of the voltage switching circuit in FIG. 9;

12 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention;

13 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention;

14 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention;

FIG. 15 is a schematic diagram of a circuit structure of a dual-energy CT provided by an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all structures related to the present invention.

Embodiments of the present invention provide a voltage switching circuit. FIG. 1 is a schematic diagram of a circuit structure of a voltage switching circuit according to an embodiment of the present invention. The voltage switching circuit can be, for example, a high-voltage generator, and its output voltage can be 1kV-1000kV. Referring to FIG. 1, the voltage switching circuit includes: a first switching output terminal 10 and a second switching output terminal 20, and a rectification and filtering module 30 connected between the first switching output terminal 10 and the second switching output terminal 20; The module 30 includes a filter unit connected to its output (Fig. 1 exemplarily shows that the filter unit includes a first filter unit 311 and a second filter unit 312), the output voltage of the rectification filter module 30 is the first voltage, and the filter The capacitance value of the unit is set as the first capacitance value, the output terminal voltage of the rectification filter module 30 is the second voltage, and the capacitance value of the filter unit is set as the second capacitance value; the first voltage is greater than the second voltage, the first The capacitance value is smaller than the second capacitance value.

The first switching output terminal 10 and the second switching output terminal 20 are the output terminals of the voltage switching circuit, and the voltage difference between the first switching output terminal 10 and the second switching output terminal 20 is the output voltage of the voltage switching circuit. The input end of the rectifier and filter module 30 can be electrically connected to, for example, the secondary side winding of the high-voltage transformer, the input voltage of the rectifier and filter module 30 is provided by the high-voltage transformer, the alternating current of the high-voltage transformer is provided by the inverter, and the rectifier and filter module 30 can input the input voltage The voltage input at the terminal is rectified and filtered.

The filter unit of the rectification filter module 30 may be composed of at least two filter capacitors. Exemplarily, the first filter unit 311 is a first filter capacitor (or an equivalent first filter capacitor), and the second filter unit 312 is a second filter capacitor. (or equivalent second filter capacitor), the capacitance values of the first filter unit 311 and the second filter unit 312 are both C, by connecting the first filter unit 311 and the second filter unit 312 in series, in parallel or only one of them is connected to in the circuit.

Exemplarily, the working process of the voltage switching circuit is, in the high-voltage working mode (output high voltage level, for example 140kV), the capacitance value of the filter unit is set to 0.5C, and the output terminal voltage of the rectification filter module 30 is the first. A voltage V_k_h; in the low voltage operating mode (output low voltage level, eg 70kV), the capacitance value of the filter unit is set to 2C, the output voltage of the rectification filter module 30 is the second voltage V_k_1, and V_k_1=0.5V_k_h.

It can be seen that, in the embodiment of the present invention, by switching the capacitance value of the filter unit of the rectification filter module 30, the capacitance value of the filter unit is set to the first capacitance value, and the output terminal voltage of the rectifier filter module 30 is the first voltage; The capacitance value of the unit is set as the second capacitance value, and the output terminal voltage of the rectification filter module 30 is the second voltage; and the voltage of the filter unit is negatively correlated with the capacitance value, which is conducive to the switching process of outputting two voltage levels In the filter unit, the charge amount of the filter unit is almost unchanged, that is, it is beneficial to reduce the charge and discharge time of the filter unit. Compared with the prior art, in the process of switching between two output voltage levels in the embodiment of the present invention, the change of the charge amount of the filter unit is small, so it is not necessary to charge and discharge the filter unit for a long time. On the one hand, the voltage switching is improved. speed, and the voltage switching speed is not affected by load current changes, on the other hand, there is no need to use an inverter with better current stress. Therefore, the embodiments of the present invention achieve the effects of increasing the voltage switching speed, reducing the cost, and widening the applicable load current range.

Continuing to refer to FIG. 1 , on the basis of the foregoing embodiments, optionally, the output end of the rectification and filtering module 30 includes a first output end 301 and a second output end 302 ; the filtering unit includes a first filtering unit 311 and a second filtering unit 311 . Unit 312 , the first end of the first filter unit 311 is electrically connected to the first output end 301 of the rectification filter module 30 , and the second end of the second filter unit 312 is electrically connected to the second output end 302 of the rectifier filter module 30 . The rectifying and filtering module 30 further includes: a first rectifying unit 320 and a first filtering switching unit 330 , the first input end 321 of the first rectifying unit 320 is used as the first input end of the rectifying and filtering The input terminal 322 is used as the second input terminal of the rectification filter module 30 , the first output terminal 323 of the first rectification unit 320 is electrically connected to the first output terminal 301 of the rectification filter module 30 , and the second output terminal 324 of the first rectification unit 320 It is electrically connected to the second output end 302 of the rectification filter module 30; the first filter switching unit 330 includes a first end 331, a second end 332, a third end 333 and a fourth end 334; The terminal 331 is electrically connected to the first output terminal 301 of the rectification filter module 30 , the second terminal 332 of the first filter switching unit 330 is electrically connected to the second terminal of the first filter unit 311 , and the third terminal of the first filter switch unit 330 333 is electrically connected to the first terminal of the second filtering unit 312, and the fourth terminal 334 of the first filtering switching unit 330 is electrically connected to the second output terminal 302 of the rectifying filtering module 30; the first filtering switching unit 330 is used for rectifying filtering When the output terminal voltage of the module 30 is the first voltage, the first filter unit 311 and the second filter unit 312 are set in series; when the output terminal voltage of the rectification filter module 30 is the second voltage, the first filter unit 311 and the second filter unit 312 are set to be connected in series. The second filtering units 312 are connected in parallel.

Wherein, the first rectifier unit 320 can convert the alternating current input at its input end into direct current, and the first rectifier unit 320 can be a full-bridge rectifier circuit, a voltage doubler rectifier circuit, or a Cockcroft-Walton (Cockcroft-Walton) circuit. Walton) circuit, Cockcroft-Walton circuit is referred to as CW circuit. Exemplarily, the working process of the rectifying and filtering module 30 is, referring to FIG. 2 , in the high-voltage working mode, the first end 331 and the third end 333 of the first filter switching unit 330 are disconnected, and the second end 332 and the fourth end 333 are disconnected. The terminal 334 is disconnected, and the first terminal 331 and the fourth terminal 334 are turned on, so that the first filter unit 311 and the second filter unit 312 are connected in series; after the series connection, the total voltage across the first filter unit 311 and the second filter unit 312 is V_k_h, the average value of the voltage output by the secondary winding of the transformer is U_s_h. Referring to FIG. 3 , in the low-voltage working mode, the first end 331 and the third end 333 of the first filter switching unit 330 are turned on, the second end 332 and the fourth end 334 are turned on, and the first end 331 and the fourth end 334 are turned on disconnected, so that the first filter unit 311 and the second filter unit 312 are connected in parallel; after the parallel connection, the voltages at both ends of the first filter unit 311 and the second filter unit 312 are both V_k_1, and the average value of the voltage output by the secondary winding of the transformer is U_s_l, and V_k_h=2V_k_l, U_s_h=2U_s_l. Assuming that the switching time between the high-voltage working mode and the low-voltage working mode tends to 0, the output voltage of the rectifier filter module 30 before and after switching satisfies V_k_h=2V_k_l. If the loss of capacitor energy during the switching process is considered, it needs to be supplemented by the inverter. V_k_h=2V_k_l is achieved after partial energy.

Among them, in the process of switching from the low-voltage working mode to the high-voltage working mode, the inverter needs to raise the voltage of the secondary winding of the transformer from U_s_1 to U_s_h. Compared with the prior art, the inverter only needs to provide maintenance The energy required by the load current does not need to provide a large amount of charging energy to the filter unit, so that the short-term high current stress of the inverter is greatly reduced. In the process of switching from the high-voltage working mode to the low-voltage working mode, the inverter needs to reduce the voltage of the secondary winding of the transformer from U_s_h to U_s_l, and the step-down process of the filter unit does not need to be accompanied by energy release, so even a small current Fast step-down can also be achieved under load.

FIG. 4 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention. On the basis of the foregoing embodiments, the embodiments of the present invention provide a specific circuit structure of the first filter switching unit 330 . Referring to FIG. 4 , optionally, the first filter switching unit 330 includes: a first transistor S1 , a second transistor S2 and a third transistor S3 . The first end of the first transistor S1 is electrically connected to the first end of the first filter switching unit 330, the second end of the first transistor S1 is electrically connected to the third end of the first filter switching unit 330; the second end of the second transistor S2 One end is electrically connected to the third end of the first filter switching unit 330, the second end of the second transistor S2 is electrically connected to the second end of the first filter switching unit 330; the first end of the third transistor S3 is electrically connected to the first filter The second terminal of the switching unit 330 is electrically connected, and the second terminal of the third transistor S3 is electrically connected to the fourth terminal of the first filtering switching unit 330; wherein, the cathode of the body diode of the transistor serves as the first terminal of the transistor; The anode of the diode acts as the second terminal of the transistor.

Wherein, the first transistor S1, the second transistor S2 and the third transistor S3 are transistors with switching functions, for example, a metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-EffectTransistor, MOSFET) or an insulated gate Bipolar transistor (Insulated Gate Bipolar Transistor, IGBT). Exemplarily, the working principle of the first filter switching unit 330 is that in the high-voltage working mode, both the first transistor S1 and the third transistor S3 are controlled to be turned off, and the second transistor S2 is controlled to be turned on, so that the first filter unit is turned on. 311 and the second filter unit 312 are connected in series; in the low-voltage operating mode, both the first transistor S1 and the third transistor S3 are controlled to be turned on, and the second transistor S2 is controlled to be turned off, so that the first filter unit 311 and the second filter unit 312 in parallel. In the embodiment of the present invention, the topology of the first filter switching unit 330 is changed through the switching device, the circuit structure is simple, and the manufacturing cost is further reduced.

FIG. 5 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention. On the basis of the foregoing embodiments, the embodiments of the present invention provide another specific circuit structure of the first filter switching unit 330 . Referring to FIG. 5 , optionally, the first filter switching unit 330 includes: a first diode D1 , a fourth transistor S4 and a fifth transistor S5 . The cathode of the first diode D1 is electrically connected to the first terminal of the first filter switching unit 330, the anode of the first diode D1 is electrically connected to the third terminal of the first filter switching unit 330; the third terminal of the fourth transistor S4 is electrically connected. One end is electrically connected to the third end of the first filter switching unit 330, the second end of the fourth transistor S4 is electrically connected to the second end of the first filter switching unit 330; the first end of the fifth transistor S5 is electrically connected to the first filter The second terminal of the switching unit 330 is electrically connected, and the second terminal of the fifth transistor S5 is electrically connected to the fourth terminal of the first filtering switching unit 330; wherein, the cathode of the body diode of the transistor is used as the first terminal of the transistor; The anode of the diode acts as the second terminal of the transistor.

Exemplarily, the working principle of the first filter switching unit 330 is, referring to FIG. 2 , in the high-voltage working mode, the fifth transistor S5 is controlled to be turned off, and the fourth transistor S4 is controlled to be turned on. To turn off, the first filter unit 311 and the second filter unit 312 are connected in series between the first output end 301 and the second output end 302 of the rectification filter module 30; in the low-voltage working mode, see FIG. 6, control the fifth transistor S5 is turned on, and the fourth transistor S4 is controlled to be turned off. Since the first diode D1 is reversely turned off, only the first filter unit 311 is connected in series between the first output end 301 and the second output end 302 of the rectification filter module 30 . The circuit structure of the embodiment of the present invention is simple, and the manufacturing cost is further reduced.

It should be noted that in the embodiment shown in FIG. 4 , the capacitance value of the filter unit is 0.5C in the high-voltage operating mode, and the capacitance value of the filter unit is 2C in the low-voltage operating mode; the embodiment shown in FIG. 5 is in the high-voltage operating mode. In the working mode, the capacitance value of the filter unit is 0.5C, and in the low-voltage working mode, the capacitance value of the filter unit is C; therefore, the capacitance value of the filter unit in the embodiment shown in FIG. 5 changes less. The embodiment shown in FIG. 4 can ensure that both the first filtering unit 311 and the second filtering unit 312 are connected to the voltage switching circuit. Therefore, the voltage (charge amount) on the first filtering unit 311 and the second filtering unit 312 be maintained. However, in the low-voltage working mode of the embodiment shown in FIG. 5 , the second filter unit 312 is not connected to the voltage switching circuit, which will cause the voltage across the second filter unit 312 to drop. During the switching process from the low-voltage working mode to the high-voltage working mode, the embodiment shown in FIG. 5 needs to recharge the second filter unit 312 , causing current fluctuations. If the voltage switching circuit provided by the embodiment of the present invention is applied to a dual-energy CT, because the CT single view time is very short, about several hundreds of μs, even if the implementation shown in FIG. 5 is adopted, in the low-voltage working mode, the The voltage drop on the second filtering unit 312 is very small, so it will not affect the normal operation of the dual-energy CT.

It should also be noted that, in the foregoing embodiments, the output voltage of the high-voltage working mode is twice the output voltage of the low-voltage working mode, which is not a limitation of the present invention. In other embodiments, the high-voltage working mode can also be set. And the low-voltage working mode is an output voltage of any value, which can be limited according to needs in practical applications.

FIG. 7 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention. Referring to FIG. 7 , on the basis of the foregoing embodiments, optionally, the voltage switching circuit includes: a first rectification and filtering module 31 , a first inverter 41 , a first transformer 51 , a second inverter 42 , a second The transformer 52 and the second rectification filter module 32 . The primary side winding of the first transformer 51 is electrically connected to the output end of the first inverter 41 ; the primary side winding of the second transformer 52 is electrically connected to the output end of the second inverter 42 . The rectifying and filtering module is the first rectifying and filtering module 31 , and the input end of the first rectifying and filtering module 31 is electrically connected to the secondary winding of the first transformer 51 ; the first output end 311 of the first rectifying and filtering module 31 is connected to the first switching output The input end of the second rectifier and filter module 32 is electrically connected to the secondary side winding of the second transformer 52 ; the first output end 321 of the second rectifier and filter module 32 is electrically connected to the second output of the first rectifier and filter module 31 The terminal 312 is electrically connected; the second output terminal 322 of the second rectification filter module 32 is electrically connected to the second switching output terminal 20 .

The first inverter 41 provides the first AC voltage to the first transformer 51 , the first transformer 51 provides the second AC voltage to the first rectification and filtering module 31 , the first inverter 41 , the first transformer 51 and the first The rectification filter module 31 constitutes the first power loop. The second inverter 42 provides the third AC voltage to the second transformer 52 , the second transformer 52 provides the fourth AC voltage to the second rectification filter module 32 , the second inverter 42 , the second transformer 52 and the second rectifier filter module 32 The module 32 constitutes a second power circuit. The first rectification and filter module 31 is any one of the rectifier and filter modules provided in the embodiment of the present invention as shown in FIGS. 1 to 6 , and the second rectifier and filter module 32 may be any one of the rectifier and filter modules provided in the embodiment of the present invention. It can also be any module with rectifying and filtering functions in the prior art. The first rectifying and filtering module 31 and the second rectifying and filtering module 32 are connected in series, and the voltage between the first switching output terminal 10 and the second switching output terminal 20 is equal to the output voltage of the first rectifying and filtering module 31 and the second rectifying and filtering module 32 . and. In the embodiment of the present invention, two power loops are respectively set for the first rectification and filter module 31 and the second rectification and filter module 32 to avoid mutual interference in different working modes. In the embodiment of the present invention, two power loops are provided to provide alternating voltage to the first rectification and filter module 31 and the second rectification and filter module 32 respectively, and the superposition of the two voltage values output by the first rectification and filter module 31 and the second rectification and filter module 32 is used. Two output voltages with arbitrary voltage levels can be obtained.

FIG. 8 is a schematic waveform diagram of an output voltage of a voltage switching circuit according to an embodiment of the present invention. Referring to FIG. 8 , on the basis of the above embodiments, optionally, the output voltage of the first switching output terminal 10 and the second switching output terminal 20 is the first voltage kV_h or the second voltage kV_1; The output voltage is kV_h-kV_1 or 2(kV_h-kV_1); the output voltage of the second rectification filter module 32 is 2kV_1-kV_h. Exemplarily, the waveform 101 in FIG. 8 is the waveform of the output voltage of the first rectifying and filtering module 31, and the output voltage of the first rectifying and filtering module 31 is switched between kV_h-kV_1 and 2 (kV_h-kV_1); the waveform 102 is the first The waveform of the output voltage of the second rectification filter module 32, the output voltage of the second rectification filter module 32 is 2kV_1-kV_h; the waveform 103 is the waveform of the output voltage of the first switching output terminal 10 and the second switching output terminal 20, and the first switching output terminal The output voltage of 10 and the second switching output 20 is switched between kV_1 and kV_h. The output voltage of the second rectifying and filtering module 32 is a constant value. When the first rectifying and filtering module 31 outputs kV_h-kV_1, the output voltage of the first switching output terminal 10 and the second switching output terminal 20 is the first voltage kV_1; When the filter module 31 outputs 2 (kV_h-kV_1), the output voltage of the first switching output terminal 10 and the second switching output terminal 20 is the first voltage kV_h. The embodiments of the present invention are set in this way to realize output voltages with two voltage levels of arbitrary values.

It should be noted that, in the above embodiment, the topology of the rectifier unit does not change during the voltage switching process, but the topology of the filter switching unit changes, so that the capacitance value of the filter unit changes, which is not a limitation of the present invention. In other embodiments, the topology structure of the rectifier unit can also be set to change, which can be set as required in practical applications.

FIG. 9 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention. Referring to FIG. 9 , on the basis of the foregoing embodiments, optionally, the output end of the rectification and filtering module 30 includes a first output end 301 and a second output end 302 ; the filtering unit includes a third filtering unit 313 and a fourth filtering unit 314 , the first end of the third filter unit 313 is electrically connected to the first output end 301 of the rectification filter module 30 , and the second end of the fourth filter unit 314 is electrically connected to the second output end 302 of the rectifier filter module 30 . The rectifying and filtering module 30 further includes: a second rectifying unit 340 and a second filtering switching unit 350; the first input end 341 of the second rectifying unit 340 serves as the first input end of the rectifying and filtering The input terminal 342 is used as the second input terminal of the rectification filter module 30 , the first output terminal 343 of the second rectification unit 340 is electrically connected to the first output terminal 301 of the rectification filter module 30 , and the second output terminal 344 of the second rectification unit 340 is electrically connected to the second output end 302 of the rectification filter module 30; the second rectifier unit 340 is used to set the second rectifier unit 340 as the first topology when the output voltage of the rectification filter module 30 is the first voltage When the output terminal voltage of the rectification filter module 30 is the second voltage, the second rectification unit 340 is set as the second topology structure; the second filter switching unit 350 includes a first terminal 351, a second terminal 352, a third terminal 353, a The fourth terminal 354 and the fifth terminal 355; the first terminal 351 of the second filtering switching unit 350 is electrically connected to the first output terminal 301 of the rectification filtering module 30, and the second terminal 352 of the second filtering switching unit 350 is electrically connected to the third filtering unit The second terminal 352 of the 313 is electrically connected, the third terminal 353 of the second filtering switching unit 350 is electrically connected to the second input terminal 342 of the rectification filtering module 30, and the fourth terminal 354 of the second filtering switching unit 350 is electrically connected to the fourth filtering unit The first end 351 of 314 is electrically connected, and the fifth end 355 of the second filter switching unit 350 is electrically connected to the second output end 302 of the rectification filter module 30; the second filter switch unit 350 is used for the output end of the rectification filter module 30 When the voltage is the first voltage, the capacitance value of the filter unit is set to the capacitance value of the third filter unit 313 or the capacitance value of the fourth filter unit 314, and when the output terminal voltage of the rectification filter module 30 is the second voltage, set The third filtering unit 313 and the fourth filtering unit 314 are connected in parallel.

The topology of the second rectification unit 340 may be a full-bridge rectification topology, a voltage doubling rectification topology or a CW rectification topology. Exemplarily, the first topology is a voltage doubling rectification topology, and the second topology is a full-bridge rectification topology. The working process of the rectifying and filtering module 30 is, referring to FIG. 10 , in the high-voltage working mode, the topology of the second rectifying unit 340 is a voltage doubling rectification topology, and the second end 352 and the third end 353 of the second filter switching unit 350 is turned on, the third terminal 353 and the fourth terminal 354 are turned on, so that the first filter unit 311 and the second filter unit 312 are connected in series, and the total voltage across the first filter unit 311 and the second filter unit 312 after the series connection is V_k_h , the average voltage output by the secondary winding of the transformer is U_s_h; referring to FIG. 11 , in the low-voltage working mode, the topology of the second rectifier unit 340 is a full-bridge rectifier topology, and the first end 351 of the second filter switching unit 350 and the fourth end 354 is turned on, and the second end 352 and the fifth end 355 are turned on, so that the first filter unit 311 and the second filter unit 312 are connected in parallel. The voltages are all V_k_l; the average voltage output by the secondary winding of the transformer is U_s_l, V_k_h=2V_k_l, and U_s_h=U_s_l.

It can be seen that no matter in the low-voltage working mode or the high-voltage working mode, the voltage of the secondary winding of the transformer remains unchanged. Compared with the prior art, in the process of switching from the low-voltage working mode to the high-voltage working mode, the inverter does not need to provide a large amount of charging energy to the filter unit, so that the short-term high current stress of the inverter is greatly reduced. . In the process of switching from the high-voltage working mode to the low-voltage working mode, the step-down process of the filter unit does not need to be accompanied by energy release, so even under a small current load, a rapid step-down can be achieved.

FIG. 12 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention. Referring to FIG. 11, on the basis of the foregoing embodiments, optionally, the second rectifier unit 340 includes: a second diode D2, a third diode D3, a fourth diode D4, a sixth transistor S6, The seventh transistor S7 and the fifth diode D5. The anode of the second diode D2 is electrically connected to the first input terminal 341 of the second rectifier unit 340, and the cathode of the second diode D2 is electrically connected to the first output terminal 343 of the second rectifier unit 340; The anode of the tube D3 is electrically connected to the second output terminal 344 of the second rectifying unit 340, the cathode of the third diode D3 is electrically connected to the first input terminal 341 of the second rectifying unit 340; the cathode of the fourth diode D4 is electrically connected is electrically connected to the first output end 343 of the second rectifier unit 340; the first end of the sixth transistor S6 is electrically connected to the second input end 342 of the second rectifier unit 340, and the second end of the sixth transistor S6 is electrically connected to the fourth second end The anode of the diode D4 is electrically connected; the second terminal of the seventh transistor S7 is electrically connected to the second input terminal 342 of the second rectifier unit 340; the anode of the fifth diode D5 is electrically connected to the second output terminal of the second rectifier unit 340 344 is electrically connected, and the cathode of the fifth diode D5 is electrically connected to the first end of the seventh transistor S7; wherein, the cathode of the body diode of the transistor serves as the first end of the transistor; the anode of the body diode of the transistor serves as the second end of the transistor. end.

The sixth transistor S6 and the seventh transistor S7 are transistors with switching functions, for example, MOSFETs or IGBTs. Exemplarily, the working principle of the second rectifying unit 340 is that in the high-voltage working mode, both the sixth transistor S6 and the seventh transistor S7 are controlled to be turned off, so that the second rectifying unit 340 has the first topology; In the working mode, both the sixth transistor S6 and the seventh transistor S7 are controlled to be turned on, so that the second rectifier unit 340 has the second topology structure. In the embodiment of the present invention, the topology structure of the second rectifier unit 340 is transformed through the switching device, the circuit structure is simple, and the cost is low.

Continuing to refer to FIG. 12 , on the basis of the foregoing embodiments, optionally, the second filter switching unit 350 includes: an eighth transistor S8 , a ninth transistor S9 , a tenth transistor S10 and an eleventh transistor S11 . The first end of the eighth transistor S8 is electrically connected to the third end 353 of the second filter switching unit 350, the second end of the eighth transistor S8 is electrically connected to the second end 352 of the second filter switching unit 350; the ninth transistor S9 The first terminal of S9 is electrically connected to the fourth terminal 354 of the second filter switching unit 350, the second terminal of the ninth transistor S9 is electrically connected to the third terminal 353 of the second filter switching unit 350; the first terminal of the tenth transistor S10 is electrically connected is electrically connected to the first end 351 of the second filter switching unit 350, the second end of the tenth transistor S10 is electrically connected to the fourth end 354 of the second filter switching unit 350; the first end of the eleventh transistor S11 is electrically connected to the second end 354 of the second filter switching unit 350; The second terminal 352 of the filter switching unit 350 is electrically connected, and the second terminal of the eleventh transistor S11 is electrically connected to the fifth terminal 355 of the second filter switching unit 350; wherein the cathode of the body diode of the transistor serves as the first terminal of the transistor ; The anode of the body diode of the transistor acts as the second terminal of the transistor.

The eighth transistor S8 , the ninth transistor S9 , the tenth transistor S10 and the eleventh transistor S11 are transistors with switching functions, for example, MOSFETs or IGBTs. Exemplarily, the working principle of the second rectifier unit 340 is that in the high-voltage working mode, both the eighth transistor S8 and the ninth transistor S9 are controlled to be turned on, and the tenth transistor S10 and the eleventh transistor S11 are controlled to be turned off, So that the first filtering unit 311 and the second filtering unit 312 are connected in series; in the low-voltage working mode, the eighth transistor S8 and the ninth transistor S9 are controlled to be turned off, and the tenth transistor S10 and the eleventh transistor S11 are controlled to be turned on. In the embodiment of the present invention, the topology structure of the second filter switching unit 350 is transformed through the switching device, the circuit structure is simple, and the manufacturing cost is further reduced.

FIG. 13 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention. Referring to FIG. 13 , on the basis of the foregoing embodiments, optionally, the voltage switching circuit further includes: a third inverter 43 , a third transformer 53 , a third rectifying and filtering module 33 and a fourth rectifying and filtering module 34 . The primary side windings of the three transformers 53 are electrically connected to the output end of the third inverter 43 ; the third transformer 53 includes a first secondary side winding and a second secondary side winding. The first input end of the third rectification filter module 33 is electrically connected to the first end 531 of the first secondary winding; the second input end of the third rectification filter module 33 is electrically connected to the second end 532 of the first secondary winding connected; the first output end 331 of the third rectifying and filtering module 33 is electrically connected to the first switching output end 10; the first input end of the fourth rectifying and filtering module 34 is electrically connected to the first end 533 of the second secondary winding; The second input terminal of the fourth rectifying and filtering module 34 is electrically connected to the second terminal 534 of the second secondary winding; the first output terminal 341 of the fourth rectifying and filtering module 34 is electrically connected to the second output terminal of the third rectifying and filtering module 33 332 is electrically connected; the second output terminal 342 of the fourth rectification filter module 34 is electrically connected to the second switching output terminal 20 .

The third inverter 43 provides the fifth AC voltage to the third transformer 53 , the third transformer 53 provides the sixth AC voltage to the third rectifying and filtering module 33 , and the third transformer 53 provides the seventh AC voltage to the fourth rectifying and filtering module 34 . The values of the AC voltage, the sixth AC voltage and the seventh AC voltage are determined by the transformation ratio of the transformer. The third rectifying and filtering module 33 is any one of the rectifying and filtering modules provided in the embodiment of the present invention as shown in FIGS. 9 to 12 , and the fourth rectifying and filtering module 34 may be any one of the rectifying and filtering modules provided in the embodiment of the present invention, It can also be any module with rectifying and filtering functions in the prior art. The third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 are connected in series, and the voltage between the first switching output terminal 10 and the second switching output terminal 20 is equal to the output voltage of the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 and. In the embodiment of the present invention, the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 are set to output two voltage values respectively, and two output voltages with arbitrary voltage levels can be obtained by superimposing the two voltage values.

On the basis of the above embodiments, optionally, the output voltage of the first switching output terminal 10 and the second switching output terminal 20 is the first voltage kV_h or the second voltage kV_1; the output voltage of the third rectifying filter module 33 is kV_h -kV_1 or 2(kV_h-kV_1); the output voltage of the fourth rectifying and filtering module 34 is 2kV_1-kV_h. Wherein, the output voltage of the fourth rectifying and filtering module 34 is a constant value, and when the third rectifying and filtering module 33 outputs kV_h-kV_1, the output voltage of the first switching output terminal 10 and the second switching output terminal 20 is the first voltage kV_1; When the output of the three rectification and filter modules 33 is 2 (kV_h-kV_1), the output voltage of the first switching output terminal 10 and the second switching output terminal 20 is the first voltage kV_h. The embodiments of the present invention are set in this way to realize output voltages with two voltage levels of arbitrary values.

It should be noted that, since the voltage output by the front-end secondary side winding of the third rectifier and filter module 33 provided by the embodiment of the present invention remains unchanged when outputting two voltage levels, the front-end secondary side of the fourth rectifier and filter module 34 remains unchanged. The voltage output by the winding remains unchanged, therefore, the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 can be connected to different windings of the third transformer 53 . Compared with setting the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 to be connected to different inverters and transformers respectively, the embodiment of the present invention further reduces the manufacturing cost of the voltage switching circuit.

FIG. 14 is a schematic diagram of a circuit structure of another voltage switching circuit provided by an embodiment of the present invention. Referring to FIG. 14 , on the basis of the above-mentioned embodiments, optionally, the number of rectification and filter modules 30 is N; wherein, the first output terminal 301 of the first rectification filter module 30 is electrically connected to the first switching output terminal 10 connected, the fourth end of the i-th rectifying and filtering module 30 is electrically connected to the first output end 301 of the i+1-th rectifying and filtering module 30, and the fourth end of the N-th rectifying and filtering module 30 is electrically connected to the second switching output end 20 Electrical connection; N≥1, 1≤i<N.

The number of the rectifier and filter modules 30 provided in the embodiment of the present invention is at least one. If the number of the rectifier and filter modules 30 is one, the output end of the rectifier filter module 30 is the output end of the voltage switching circuit; if the number of the rectifier filter modules 30 is Multiple (two or more), multiple rectifier filter modules 30 are connected in series, and the specific connection method is that the first output terminal of the first rectifier filter module 30 is electrically connected to the first switching output terminal 10, and the first The second output terminal of the rectification filter module 30 is electrically connected to the first output terminal of the second rectification filter module 30 , and so on, the second output terminal of the last rectification filter module 30 is electrically connected to the second switch output terminal 20 . In practical applications, the specific number of the rectifying and filtering modules 30 connected in series can be set as required.

On the basis of the above embodiments, optionally, the voltage switching circuit further includes: a control system, the control system is connected to the voltage switching circuit, and is used for controlling the voltage of the voltage output terminal of the voltage switching circuit. The voltage switching circuit may include, for example, circuit structures such as an inverter, a rectifier unit, and a filter switching unit. In these circuit structures, for example, a variety of transistors may be included, and the control terminals of these transistors can be controlled by the control system to control the turn-on and turn-off of these transistors, thereby switching the topology of the circuit, thereby realizing the switching of voltage levels.

The embodiment of the present invention also provides a dual-energy CT. FIG. 15 is a schematic diagram of a circuit structure of a dual-energy CT provided by an embodiment of the present invention. Referring to FIG. 15 , the dual-energy CT includes: the voltage switching circuit 1 and the bulb 2 provided by any embodiment of the present invention; the power supply end of the bulb 2 is electrically connected to the voltage output end of the voltage switching circuit, and the high-voltage generator is used to send the bulb Tube power supply. The voltage output terminal of the voltage switching circuit 1 includes a first switching output terminal 10 and a second switching output terminal 20 , and the voltage difference between the first switching output terminal 10 and the second switching output terminal 20 is the output of the voltage switching circuit 1 Voltage.

In the embodiment of the present invention, by switching the capacitance value of the filter unit of the rectification filter module in the voltage switching circuit 1, the capacitance value of the filter unit is set to the first capacitance value, and the output terminal voltage of the rectifier filter module is the first voltage; the filter unit The capacitance value of the rectifier is set as the second capacitance value, and the output terminal voltage of the rectification filter module is the second voltage; and the voltage of the filter unit is negatively correlated with the capacitance value, which is conducive to the switching process of outputting two voltage levels. The charge amount of the filter unit is almost unchanged, which is beneficial to reduce the charging and discharging time of the filter unit. Compared with the prior art, in the process of switching between two output voltage levels in the embodiment of the present invention, the change of the charge amount of the filter unit is small, so it is not necessary to charge and discharge the filter unit for a long time. On the one hand, the voltage switching is improved. speed, and the voltage switching speed is not affected by load current changes, on the other hand, there is no need to use an inverter with better current stress. Therefore, the embodiments of the present invention achieve the effects of increasing the voltage switching speed, reducing the cost, and widening the applicable load current range.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention. The scope is determined by the scope of the appended claims.

Claims (18)

1. A voltage switching circuit, comprising: the first switching output end and the second switching output end, and a rectification filter module connected between the first switching output end and the second switching output end;

the rectification filter module comprises a filter unit connected to the output end of the rectification filter module, the voltage of the output end of the rectification filter module is a first voltage, the capacitance value of the filter unit is set as a first capacitance value, the voltage of the output end of the rectification filter module is a second voltage, and the capacitance value of the filter unit is set as a second capacitance value; the first voltage is greater than the second voltage, and the first capacitance value is less than the second capacitance value;

the output end of the rectifying and filtering module comprises a first output end and a second output end;

the filtering unit comprises a first filtering unit and a second filtering unit, wherein a first end of the first filtering unit is electrically connected with a first output end of the rectification filtering module, and a second end of the second filtering unit is electrically connected with a second output end of the rectification filtering module;

the rectification filtering module comprises:

a first input end of the first rectifying unit is used as a first input end of the rectifying and filtering module, a second input end of the first rectifying unit is used as a second input end of the rectifying and filtering module, a first output end of the first rectifying unit is used as a first output end of the rectifying and filtering module, and a second output end of the first rectifying unit is used as a second output end of the rectifying and filtering module;

the first filtering switching unit comprises a first end, a second end, a third end and a fourth end; a first end of the first filtering switching unit is electrically connected with a first output end of the rectifying and filtering module, a second end of the first filtering switching unit is electrically connected with a second end of the first filtering unit, a third end of the first filtering switching unit is electrically connected with a first end of the second filtering unit, and a fourth end of the first filtering switching unit is electrically connected with a second output end of the rectifying and filtering module; the first filtering switching unit is used for setting the first filtering unit and the second filtering unit to be connected in series when the output end voltage of the rectifying and filtering module is a first voltage, and setting the first filtering unit and the second filtering unit to be connected in parallel when the output end voltage of the rectifying and filtering module is a second voltage.

2. The voltage switching circuit according to claim 1, wherein the first filter switching unit includes:

a first transistor, a first end of which is electrically connected with a first end of the first filtering switching unit, and a second end of which is electrically connected with a third end of the first filtering switching unit;

a first end of the second transistor is electrically connected with a third end of the first filtering switching unit, and a second end of the second transistor is electrically connected with a second end of the first filtering switching unit;

a third transistor, a first end of the third transistor being electrically connected to the second end of the first filtering switching unit, and a second end of the third transistor being electrically connected to the fourth end of the first filtering switching unit;

wherein a cathode of a body diode of a transistor serves as a first terminal of the transistor; an anode of a body diode of the transistor serves as a second terminal of the transistor.

3. The voltage switching circuit of claim 2, wherein the first transistor, the second transistor, and the third transistor are MOSFETs or IGBTs.

4. The voltage switching circuit according to claim 1, wherein the first filter switching unit includes:

a cathode of the first diode is electrically connected with a first end of the first filter switching unit, and an anode of the first diode is electrically connected with a third end of the first filter switching unit;

a first end of the fourth transistor is electrically connected with the third end of the first filtering switching unit, and a second end of the fourth transistor is electrically connected with the second end of the first filtering switching unit;

a fifth transistor, a first end of which is electrically connected to the second end of the first filtering switching unit, and a second end of which is electrically connected to the fourth end of the first filtering switching unit;

wherein a cathode of a body diode of a transistor serves as a first terminal of the transistor; an anode of a body diode of the transistor serves as a second terminal of the transistor.

5. The voltage switching circuit of claim 1, wherein the first rectifying unit is: a full bridge rectifier circuit, a voltage doubler rectifier circuit or a Kockcroft-Walton circuit.

6. The voltage switching circuit according to any one of claims 1 to 5, wherein the rectifying and filtering module is a first rectifying and filtering module;

the voltage switching circuit further includes:

a first inverter;

a first transformer, a primary side winding of which is electrically connected with an output end of the first inverter; the input end of the first rectifying and filtering module is electrically connected with a secondary side winding of the first transformer; the first output end of the first rectifying and filtering module is electrically connected with the first switching output end;

a second inverter;

a second transformer, a primary winding of which is electrically connected to an output terminal of the second inverter;

the input end of the second rectifying and filtering module is electrically connected with a secondary side winding of the second transformer; the first output end of the second rectifying and filtering module is electrically connected with the second output end of the first rectifying and filtering module; and the second output end of the second rectifying and filtering module is electrically connected with the second switching output end.

7. The voltage switching circuit of claim 6, further comprising:

the output voltage of the first switching output end and the second switching output end is a first voltage kV _ h or a second voltage kV _ l;

the output voltage of the first rectifying and filtering module is kV _ h-kV _ l or 2(kV _ h-kV _ l);

the output voltage of the second rectifying and filtering module is 2kV _ l-kV _ h.

8. The voltage switching circuit of claim 1, further comprising: the number of the rectification filter modules is N;

a first output end of the first rectifying and filtering module is electrically connected with the first switching output end, a fourth end of the ith rectifying and filtering module is electrically connected with a first output end of the (i + 1) th rectifying and filtering module, and a fourth end of the nth rectifying and filtering module is electrically connected with the second switching output end; n is more than or equal to 1, and i is more than or equal to 1 and less than N.

9. The voltage switching circuit of claim 1, further comprising:

and the control system is connected with the voltage switching circuit and is used for controlling the voltage of the voltage output end of the voltage switching circuit.

10. A dual energy CT, comprising: the voltage switching circuit and bulb of any one of claims 1-9;

the power supply end of the bulb tube is electrically connected with the voltage output end of the voltage switching circuit, and the voltage switching circuit is used for supplying power to the bulb tube.

11. A voltage switching circuit, comprising: the first switching output end and the second switching output end, and a rectification filter module connected between the first switching output end and the second switching output end;

the rectification filter module comprises a filter unit connected to the output end of the rectification filter module, the voltage of the output end of the rectification filter module is a first voltage, the capacitance value of the filter unit is set as a first capacitance value, the voltage of the output end of the rectification filter module is a second voltage, and the capacitance value of the filter unit is set as a second capacitance value; the first voltage is greater than the second voltage, and the first capacitance value is less than the second capacitance value;

the output end of the rectifying and filtering module comprises a first output end and a second output end;

the filtering unit comprises a third filtering unit and a fourth filtering unit, wherein the first end of the third filtering unit is electrically connected with the first output end of the rectification filtering module, and the second end of the fourth filtering unit is electrically connected with the second output end of the rectification filtering module;

the rectification filtering module comprises:

a first input end of the second rectifying unit is used as a first input end of the rectifying and filtering module, a second input end of the second rectifying unit is used as a second input end of the rectifying and filtering module, a first output end of the second rectifying unit is electrically connected with a first output end of the rectifying and filtering module, and a second output end of the second rectifying unit is electrically connected with a second output end of the rectifying and filtering module; the second rectifying unit is used for setting the second rectifying unit to be in a first topological structure when the voltage at the output end of the rectifying and filtering module is a first voltage, and setting the second rectifying unit to be in a second topological structure when the voltage at the output end of the rectifying and filtering module is a second voltage;

the second filtering switching unit comprises a first end, a second end, a third end, a fourth end and a fifth end; a first end of the second filtering switching unit is electrically connected with a first output end of the rectifying and filtering module, a second end of the second filtering switching unit is electrically connected with a second end of the third filtering unit, a third end of the second filtering switching unit is electrically connected with a second input end of the rectifying and filtering module, a fourth end of the second filtering switching unit is electrically connected with a first end of the fourth filtering unit, and a fifth end of the second filtering switching unit is electrically connected with a second output end of the rectifying and filtering module; the second filtering switching unit is used for setting the capacitance value of the filtering unit as the capacitance value of the third filtering unit or the capacitance value of the fourth filtering unit when the output end voltage of the rectifying and filtering module is a first voltage, and setting the third filtering unit and the fourth filtering unit to be connected in parallel when the output end voltage of the rectifying and filtering module is a second voltage.

12. The voltage switching circuit according to claim 11, wherein the second rectifying unit comprises:

the anode of the second diode is electrically connected with the first input end of the second rectifying unit, and the cathode of the second diode is electrically connected with the first output end of the second rectifying unit;

the anode of the third diode is electrically connected with the second output end of the second rectifying unit, and the cathode of the third diode is electrically connected with the first input end of the second rectifying unit;

a cathode of the fourth diode is electrically connected with the first output end of the second rectifying unit;

a sixth transistor, a first end of which is electrically connected to the second input end of the second rectifying unit, and a second end of which is electrically connected to an anode of the fourth diode;

a seventh transistor, a second end of the seventh transistor being electrically connected to the second input end of the second rectifying unit;

an anode of the fifth diode is electrically connected with the second output end of the second rectifying unit, and a cathode of the fifth diode is electrically connected with the first end of the seventh transistor;

wherein a cathode of a body diode of a transistor serves as a first terminal of the transistor; an anode of a body diode of the transistor serves as a second terminal of the transistor.

13. The voltage switching circuit according to claim 11, wherein the second filter switching unit comprises:

a first end of the eighth transistor is electrically connected with the third end of the second filtering switching unit, and a second end of the eighth transistor is electrically connected with the second end of the second filtering switching unit;

a ninth transistor, a first end of which is electrically connected to the fourth end of the second filtering switching unit, and a second end of which is electrically connected to the third end of the second filtering switching unit;

a tenth transistor, a first end of the tenth transistor is electrically connected to the first end of the second filtering switching unit, and a second end of the tenth transistor is electrically connected to the fourth end of the second filtering switching unit;

a first end of the eleventh transistor is electrically connected with the second end of the second filtering switching unit, and a second end of the eleventh transistor is electrically connected with the fifth end of the second filtering switching unit;

wherein a cathode of a body diode of a transistor serves as a first terminal of the transistor; an anode of a body diode of the transistor serves as a second terminal of the transistor.

14. The voltage switching circuit according to any one of claims 11-13, wherein the rectifying-filtering module is a third rectifying-filtering module;

the voltage switching circuit further includes:

a third inverter;

a third transformer, a primary winding of which is electrically connected to an output terminal of the third inverter; the third transformer comprises a first secondary side winding and a second secondary side winding; a first input end of the third rectifying and filtering module is electrically connected with a first end of the first secondary side winding; a second input end of the third rectifying and filtering module is electrically connected with a second end of the first secondary side winding; the first output end of the third rectifying and filtering module is electrically connected with the first switching output end;

a first input end of the fourth rectifying and filtering module is electrically connected with a first end of the second secondary side winding; a second input end of the fourth rectifying and filtering module is electrically connected with a second end of the second secondary side winding; the first output end of the fourth rectifying and filtering module is electrically connected with the second output end of the third rectifying and filtering module; and a second output end of the fourth rectifying and filtering module is electrically connected with the second switching output end.

15. The voltage switching circuit of claim 14, further comprising:

the output voltage of the first switching output end and the second switching output end is a first voltage kV _ h or a second voltage kV _ l;

the output voltage of the third rectifying and filtering module is kV _ h-kV _ l or 2(kV _ h-kV _ l);

the output voltage of the fourth rectifying and filtering module is 2kV _ l-kV _ h.

16. The voltage switching circuit of claim 11, further comprising: the number of the rectification filter modules is N;

a first output end of the first rectifying and filtering module is electrically connected with the first switching output end, a fifth end of the ith rectifying and filtering module is electrically connected with a first output end of the (i + 1) th rectifying and filtering module, and a fifth end of the nth rectifying and filtering module is electrically connected with the second switching output end; n is more than or equal to 1, and i is more than or equal to 1 and less than N.

17. The voltage switching circuit of claim 11, further comprising:

and the control system is connected with the voltage switching circuit and is used for controlling the voltage of the voltage output end of the voltage switching circuit.

18. A dual energy CT, comprising: the voltage switching circuit and bulb of any one of claims 11-17;

the power supply end of the bulb tube is electrically connected with the voltage output end of the voltage switching circuit, and the voltage switching circuit is used for supplying power to the bulb tube.

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