JPWO2018198204A1 - Overcurrent protection device, inverter device, converter device and air conditioner - Google Patents

Abstract

The overcurrent protection device (120) includes a first filter circuit (21) for filtering a detected value of the current flowing through the upper and lower arms with a first time constant, and a second filter whose detected value is longer than the first time constant. A second filter circuit (22) that filters by a time constant, a first cutoff circuit (23) that sets a first overcurrent determination value, and a second overcurrent that is smaller than the first overcurrent determination value A second cutoff circuit (24) for setting a determination value, and after the first time constant has elapsed after the detection value exceeding the first overcurrent determination value is detected, the operation of the first semiconductor switching element And the operation of the second semiconductor switching element is stopped after the second time constant has elapsed since the detection value exceeding the second overcurrent determination value is detected.

Description

  The present invention relates to an overcurrent protection device, an inverter device, a converter device, and an air conditioner that protect a semiconductor switching element from an overcurrent.

  A conventional inverter device disclosed in Patent Document 1 includes a control unit that generates an upper arm control signal and a lower arm control signal, and a cut signal generation that generates an upper arm cut signal and a lower arm cut signal when an overcurrent is detected. Circuit. The upper arm cutoff signal is obtained by delaying the lower arm cutoff signal using the delay circuit, and the upper arm control signal is cut off after a predetermined time has elapsed since the lower arm control signal was cut off by the lower arm cutoff signal. The

JP 2008-118834 A

  However, in the conventional inverter device disclosed in Patent Document 1, one overcurrent determination value is used. That is, in the conventional inverter device, the determination value having the smaller value out of the determination value for protecting the motor and the determination value for protecting the semiconductor switching element is set as the overcurrent determination value. If the excessive short-circuit current that flows when the upper and lower arms are short-circuited is “Ia” and the current that can be passed to the motor with built-in magnet is “Ib”, the current is cut off at high speed when the short-circuit current Ia flows to the upper and lower arms. There is a need to. “High speed” means that the time constant of the filter circuit is set to 1 [us] or less, for example. On the other hand, Ib is determined by restrictions on demagnetization of the motor magnet. For example, in the case of Ib <Ia, it is necessary to set the overcurrent determination value to Ib in order to protect the motor. In the above example, in order to protect the semiconductor switching element from the short circuit of the upper and lower arms, the filter circuit It is necessary to set the time constant to 1 [us] or less. In this case, since the overcurrent determination value is set to Ib lower than Ia and the filter time constant is short, there is a problem that overcurrent protection frequently operates due to the influence of noise or the like, that is, overcurrent protection is unnecessary. there were.

  The present invention has been made in view of the above, and an object thereof is to obtain an overcurrent protection device capable of protecting a semiconductor switching element from an overcurrent while preventing an unnecessary operation of overcurrent protection.

  In order to solve the above-described problems and achieve the object, the overcurrent protection device of the present invention includes a current flowing through upper and lower arms configured by connecting a first semiconductor switching element and a second semiconductor switching element in series. A first filter circuit that filters the detected value with a first time constant, a second filter circuit that filters the detected value with a second time constant longer than the first time constant, and a first overcurrent A first determination value setting unit configured to set a determination value; and a second determination value setting unit configured to set a second overcurrent determination value smaller than the first overcurrent determination value. After the detection value exceeding the determination value is detected, after the first time constant has elapsed, the operation of the first semiconductor switching element is stopped, and the detection value exceeding the second overcurrent determination value is detected. After the elapse of the time constant of 2, the second semiconductor switching element To stop the work.

  The overcurrent protection device according to the present invention has an effect that the semiconductor switching element can be protected from overcurrent while preventing unnecessary operation of overcurrent protection.

The figure which shows the structural example of the overcurrent protection apparatus and inverter apparatus which concern on Embodiment 1 of this invention. The figure which shows the structural example of the overcurrent protection apparatus shown in FIG. The figure which shows the overcurrent protection operation | movement of the overcurrent protection apparatus which concerns on Embodiment 1 of this invention. The figure which shows another example of overcurrent judgment value and overcurrent protection operation The figure which shows the relationship between I1 and I2 which are shown to FIG. The figure which shows the structural example of the overcurrent protection circuit which concerns on Embodiment 2 of this invention. The figure which shows the structural example of the converter apparatus which concerns on Embodiment 3 of this invention. The figure which shows the structural example of the air conditioner which concerns on Embodiment 4 of this invention.

  Hereinafter, an overcurrent protection device, an inverter device, a converter device, and an air conditioner according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of an overcurrent protection device and an inverter device according to Embodiment 1 of the present invention. An inverter device 100 shown in FIG. 1 is a motor drive device that rectifies an AC voltage supplied from an AC power supply 1, converts the rectified voltage into an AC voltage, and supplies the AC voltage to a motor 200 that is a load. The motor 200 can be exemplified by a three-phase synchronous motor or a three-phase induction motor. The inverter device 100 includes a rectifier 2 that rectifies the AC power supply 1, a capacitor 3 that smoothes the voltage rectified by the rectifier 2, an inverter circuit 110, and an overcurrent protection device 120.

  The inverter circuit 110 includes an upper arm circuit 18 and a lower arm circuit 19. The upper arm circuit 18 includes three semiconductor switching elements 6 to 8 and three diodes 12 to 14 connected in parallel to the three semiconductor switching elements 6 to 8. The lower arm circuit 19 includes three semiconductor switching elements 9 to 11 and three diodes 15 to 17 connected in parallel to the three semiconductor switching elements 9 to 11.

  A connection point between the semiconductor switching element 6 and the semiconductor switching element 9 is connected to the U-phase wiring, a connection point between the semiconductor switching element 7 and the semiconductor switching element 10 is connected to the V-phase wiring, and the semiconductor switching element 8 and the semiconductor are connected. A connection point with the switching element 11 is connected to a W-phase wiring.

  The number of semiconductor switching elements constituting each of the upper arm circuit 18 and the lower arm circuit 19 is not limited to three, and the diodes 12 to 14 may be parasitic diodes built in the semiconductor switching elements 6 to 8, The diodes 15 to 17 may be parasitic diodes built in the semiconductor switching elements 9 to 11.

  The overcurrent protection device 120 includes a current detector 20 that detects a current flowing from the inverter circuit 110 to the negative side of the capacitor 3, a first filter circuit 21 in which a first time constant t1 is set, and a second And a second filter circuit 22 in which a time constant t2 is set. The overcurrent protection device 120 includes a first cutoff circuit 23 that shuts off the drive signal 30 that drives the three semiconductor switching elements 6 to 8 that constitute the upper arm circuit 18, and three semiconductors that constitute the lower arm circuit 19. A second cutoff circuit 24 that shuts off the drive signal 31 that drives the switching elements 9 to 11 and a controller 5 for controlling the inverter circuit 110 are provided.

  The first time constant t1 and the second time constant t2 are times from when the overcurrent occurs until the semiconductor switching element in the inverter device 100 is cut off. Hereinafter, the “first time constant t1” may be simply referred to as “t1”, and the “second time constant t2” may be simply referred to as “t2”.

  The control unit 5 outputs a control signal 27 for ON / OFF control of the upper arm circuit 18 to the first cutoff circuit 23. The output from the current detector 20 is input to the first filter circuit 21 and the second filter circuit 22. The output from the current detector 20 is a detected value of the current flowing through the upper and lower arms configured by connecting the first semiconductor switching element and the second semiconductor switching element in series. The “first semiconductor switching element” corresponds to each of the semiconductor switching elements 6 to 8, and the “second semiconductor switching element” corresponds to each of the semiconductor switching elements 9 to 11.

  When the output of the first filter circuit 21 is input to the first cutoff circuit 23 and the first cutoff circuit 23 does not determine that the current is an overcurrent, the drive signal 30 becomes a drive signal similar to the control signal 27 and the first cutoff circuit 23 When the interruption circuit 23 determines that the current is an overcurrent, the drive signal 30 is interrupted. As a result, the operation of the upper arm circuit 18 is stopped.

  Similarly, the output of the second filter circuit 22 is input to the second cutoff circuit 24, and when the second cutoff circuit 24 does not determine an overcurrent, the drive signal 31 becomes a drive signal similar to the control signal 28, When the second cutoff circuit 24 determines that the current is overcurrent, the drive signal 31 is cut off. As a result, the operation of the lower arm circuit 19 is stopped.

  FIG. 2 is a diagram showing a configuration example of the overcurrent protection device shown in FIG. According to the overcurrent protection device 120 shown in FIG. 2, when the control signals 27 and 28 and the drive signals 30 and 31 are Hi, the semiconductor switching element is turned on, and the control signals 27 and 28 and the drive signals 30 and 31 are Lo. In this case, the semiconductor switching element is turned off. When the cutoff signals 25, 26, 41, and 42 are Hi, the semiconductor switching element is in a normal state. However, the combination of these logics is an example and can be changed as appropriate.

  The first cutoff circuit 23 includes a first determination value setting unit 34, a comparator 32, a logic circuit 37, and a first drive signal generation unit 38. The second cutoff circuit 24 includes a second determination value setting unit 35, a comparator 33, a latch circuit 29, and a second drive signal generation unit 39.

  The first filter circuit 21 and the second filter circuit 22 are constituted by RC filters. The first determination value setting unit 34 outputs a first determination value 34 a for overcurrent interruption of the upper arm circuit 18. The first determination value 34a is set by a resistance voltage dividing ratio. An upper arm overcurrent determination value I1 to be described later is set by the first determination value 34a. The second determination value setting unit 35 outputs a second determination value 35 a for overcurrent interruption of the lower arm circuit 19. The second determination value 35a is set by a resistance voltage dividing ratio. A lower arm overcurrent determination value I2, which will be described later, is set by the second determination value 35a.

  The output of the first filter circuit 21 and the first determination value 34a are compared by the comparator 32. When the output of the first filter circuit 21 exceeds the first determination value 34a, the output of the comparator 32 is A certain cut-off signal 25 becomes Lo. The logic circuit 37 calculates the logical product of the cutoff signal 26 and the cutoff signal 25 output from the latch circuit 29. When the cutoff signal 26 and the cutoff signal 25 are Lo, the logic circuit 37 outputs the cutoff signal 42 at the Lo level. To do. The first drive signal generator 38 calculates the logical product of the cutoff signal 42 and the control signal 27, and the drive signal 30 becomes Lo, whereby the upper arm circuit 18 shown in FIG.

  Similarly, the output of the second filter circuit 22 and the second determination value 35a are compared by the comparator 33. If the output of the second filter circuit 22 exceeds the second determination value 35a, the comparator 33 The cut-off signal 41 which is the output of No. becomes Lo. When the holding state of the latch circuit 29 is not reset by the reset signal 40 from the control unit 5, the cutoff signal 26 output from the latch circuit 29 becomes Lo. The second drive signal generator 39 calculates the logical product of the cutoff signal 26 and the control signal 28, and the drive signal 31 becomes Lo, whereby the lower arm circuit 19 shown in FIG.

  Here, the latch circuit 29 is a circuit that outputs the Lo level cutoff signal 26 when the cutoff signal 41 changes from Hi to Lo, and the holding state is reset by the reset signal 40 from the control unit 5. Alternatively, the holding state may be reset after holding for a certain time, for example, 1 [ms]. FIG. 2 shows a configuration example of a circuit in which the upper arm circuit 18 is cut off at the same time as the lower arm circuit 19 is cut off when the cut-off signal 26 is input to the logic circuit 37, but without providing the logic circuit 37, The cutoff signal 25 may be directly input to the first drive signal generator 38.

  Further, the overcurrent protection device 120 can detect that the control unit 5 is in a cutoff state, that is, an overcurrent has occurred by inputting the cutoff signals 25 and 26 to the control unit 5. Depending on the setting of the first determination value 34a and the second determination value 35a, either the upper arm circuit 18 or the lower arm circuit 19 is stopped in the cut-off state, and thus the control of the motor 200 may become unstable. There is. In this case, the control unit 5 detects the shut-off state, and outputs the control signals 27 and 28 for turning off the semiconductor switching elements, that is, the Lo level control signals 27 and 28, thereby stopping the entire inverter circuit 110. You can also.

  FIG. 3 is a diagram showing an overcurrent protection operation of the overcurrent protection device according to Embodiment 1 of the present invention. In FIG. 3, in order from the top, the control signal 27, the drive signal 30, the upper arm cutoff signal 25, the output of the current detector 20, the lower arm cutoff signal 26, the control signal 28, and the drive signal 31 Is shown. The upper arm overcurrent determination value I1, which is the first overcurrent determination value, is set by the first determination value 34a shown in FIG. Hereinafter, the “upper arm overcurrent determination value I1” may be simply referred to as “I1”. The lower arm overcurrent determination value I2, which is the second overcurrent determination value, is set by the second determination value 35a shown in FIG. Hereinafter, the “lower arm overcurrent determination value I2” may be simply referred to as “I2”.

  In FIG. 3, I1 and I2 satisfy I1> I2. The upper arm overcurrent cutoff release value I1 'is set to I1 or less. Hereinafter, the “upper arm overcurrent cutoff release value I1 ′” may be simply referred to as “I1 ′”. t 1 is set by the first filter circuit 21, and t 2 is set by the second filter circuit 22. In FIG. 3, t1 and t2 are set to t1 <t2, and are each within 10 [us].

  After the elapse of t1 from the time when the output of the current detector 20 exceeds I1, the cutoff signal 25 is output, and the semiconductor switching element constituting the upper arm circuit 18 is cut off and stopped. Thereafter, when the output of the current detector 20 becomes equal to or lower than I1 ′, the protection state of the upper arm circuit 18 is released, and the semiconductor switching elements constituting the upper arm circuit 18 are turned ON / OFF according to the control signal 27.

  After that, the output of the current detector 20 that has decreased to I1 ′ or less rises again, and after t2 has elapsed from the time when I2 is exceeded, a cutoff signal 26 is output, and the semiconductor switching element that constitutes the lower arm circuit 19 is cut off. Stop.

  As described above, the latch circuit 29 outputs the shut-off signal 26 maintained in the Lo state when the shut-off signal 41 changes from Hi to Lo, and after a lapse of a certain time t3 from the time when the Lo state shut-off signal 26 is output. This is a circuit for canceling the protection state of the semiconductor switching elements constituting the lower arm circuit 19. After the protection state is released, the semiconductor switching element constituting the lower arm circuit 19 operates again according to the control signal 28.

  Here, in FIG. 3, when the output of the current detector 20 exceeds I1, the output of the current detector 20 also exceeds I2 from the relationship of I1> I2, but t1 <t2 is set. Therefore, when the output of the current detector 20 rises quickly, the upper arm cutoff signal 25 is output first, and the semiconductor switching elements constituting the upper arm circuit 18 are cut off and stopped. For this reason, the cutoff signal 26 is not in the Lo state until t2.

  FIG. 4 is a diagram illustrating another example of the overcurrent determination value and the overcurrent protection operation. The parts denoted by the same reference numerals as those in FIG. After t1 elapses from the time when the output of the current detector 20 exceeds I1, the cutoff signal 25 is output, and the semiconductor switching elements constituting the upper arm circuit 18 are stopped. Thereafter, when the control signal 27 from the control unit 5 is turned off and the control signal 27 is turned on again, the protection state of the upper arm circuit 18 is released, and the upper arm circuit 18 is configured again according to the control signal 27. The semiconductor switching element is turned ON / OFF. Other operations are the same as those described above with reference to FIG.

  In FIG. 4, the protection release condition is when the control signal 27 changes from the OFF state to the ON state, but the protection release condition is not limited to this. In FIG. 3, the current state of the output of the current detector 20 exceeds I1, and after the elapse of t1, the cutoff state is released. When the output of the current detector 20 becomes equal to or lower than I1 ′ thereafter, the cutoff state is released. However, if the control signal 27 remains in the ON state, the interruption state and the release are repeated, and thus an overcurrent around I1 may continue to flow. On the other hand, by performing the control as shown in FIG. 4, since the protection is not released until the control signal 27 is once turned off and then turned on again, it is possible to prevent the overcurrent from continuing to flow.

  FIG. 5 is a diagram showing the relationship between I1 and I2 and the overcurrent cutoff operation region shown in FIGS. The vertical axis in FIG. 5 represents the overcurrent determination value, and the horizontal axis represents time. The symbols I1, I2, t1, t2, and t3 are equal to I1, I2, t1, t2, and t3 shown in FIGS. The immovable region indicated by reference numeral A1 includes the upper arm circuit 18 and the lower arm when a short-circuit current less than I1 flows less than t2 because one of the upper and lower arm pairs shown in FIG. This is a region where none of the arm circuits 19 is cut off. That is, the non-moving area A1 is an area where the overcurrent protection operation does not work.

  The region indicated by reference sign A2 is a region that shuts off the lower arm circuit 19 when a short-circuit current that is greater than or equal to I2 and less than I1 flows for t2 or more. The region indicated by reference numeral A3 is a region that shuts off the upper arm circuit 18 when a short-circuit current of I1 or more flows for t1 or more. The region indicated by reference numeral A4 is a region where the upper arm circuit 18 and the lower arm circuit 19 are cut off when a short-circuit current of I1 or more flows for t2 or more.

  This will be specifically described. When the semiconductor switching elements 6 and 9 are turned on, the semiconductor switching elements 7 and 10 are turned on, or the semiconductor switching elements 8 and 11 are turned on, the upper arm circuit 18, the lower arm circuit 19 and the A current flows to the low potential side of the capacitor 3 via the current detector 20. Since the inductance of the path through which this current flows is extremely low, the current sharply increases and a large current of I1 or more flows. When such a current flows, the overcurrent protection device 120 instantaneously cuts off the drive signal 30 when t1 elapses from the time when the output of the current detector 20 exceeds I1, and prevents destruction due to a short circuit.

  On the other hand, when an overcurrent flows through the motor winding, the inductance is high because the motor winding is in a path through which the current flows, and the current gradually increases. When such a current flows, the overcurrent protection device 120 stops the lower arm circuit 19 by cutting off the drive signal 31 when t2 elapses from the time when I2 smaller than I1 is exceeded, and the motor 200 or semiconductor switching Prevents device destruction.

When the semiconductor switching element is made of GaN (gallium nitride) or Ga ₂ O ₃ (gallium oxide), which is an example of a wide band gap semiconductor, the semiconductor switching element has low short-circuit tolerance, so that the semiconductor switching of the upper and lower arms is performed. When the element is short-circuited, it is necessary to shut off and stop instantaneously. If t1 which is the time until the stoppage is stopped is set to a small value, for example, 200 [ns], it is possible to prevent a short circuit breakage by shutting off the upper arm. In this case, since t1 is small, there is a high possibility of malfunction due to noise or the like. Therefore, when the control signal 27 is once turned off and then turned on again, the protection of the upper arm is released and the operation can be continued.

  For overcurrent passing through the motor winding, lower arm circuit is set by setting I2 smaller than I1 as described above and t2 larger than t1 and less susceptible to noise, for example, 3 [us]. 19 can be shut off and stopped safely, and frequent shutoff due to noise can be prevented.

  As shown in FIG. 2, by inputting the cutoff signals 25 and 26 to the control unit 5, the control unit 5 can determine which of the cutoff signals 25 and 26 is in the cutoff state. Thereby, the abnormal state of the inverter circuit 110 can also be determined. For example, when the upper arm circuit 18 is cut off, that is, when the cut signal 25 is cut off, it is determined that the upper and lower arms are short-circuited, and when the lower arm circuit 19 is cut off, that is, the cut signal 26 is turned off. It can be determined that an abnormality in which overcurrent flows through the motor winding, for example, motor lock has occurred.

Embodiment 2. FIG.
FIG. 6 is a diagram illustrating a configuration example of the overcurrent protection circuit according to the second embodiment of the present invention. In FIG. 6, the same reference numerals as those in FIG. The overcurrent protection device 120 shown in FIG. 2 is different from the overcurrent protection device 120 shown in FIG. 6 in that the first drive signal generator 38 is omitted and the control signal 27 is the drive signal shown in FIG. 30, the cutoff signal 26 is input only to the logic circuit 37 and the control unit 5, and the cutoff signal 42 is input to the second drive signal generation unit 39.

  According to the overcurrent protection device 120 shown in FIG. 6, when the control signals 27 and 28 and the drive signal 31 are Hi, the semiconductor switching element is turned on, and when the control signals 27 and 28 and the drive signal 31 are Lo, When the semiconductor switching element is turned off and the cut-off signals 25, 26, 41, and 42 are Hi, the normal state is obtained, and when the cut-off signals 25, 26, 41, and 42 are Lo, the cut-off state is obtained. However, the combination of these logics is an example and can be changed as appropriate.

  The output of the first filter circuit 21 and the first determination value 34a are compared by the comparator 32. When the output of the first filter circuit 21 exceeds the first determination value 34a, the output of the comparator 32 is A certain cut-off signal 25 becomes Lo. The logic circuit 37 calculates the logical product of the cutoff signal 26 and the cutoff signal 25 output from the latch circuit 29. When the cutoff signal 26 and the cutoff signal 25 are Lo, the logic circuit 37 outputs the cutoff signal 42 at the Lo level. To do.

  Similarly, the output of the second filter circuit 22 and the second determination value 35a are compared by the comparator 33. If the output of the second filter circuit 22 exceeds the second determination value 35a, the comparator 33 The cut-off signal 41 which is the output of No. becomes Lo. When the holding state of the latch circuit 29 is not reset by the reset signal 40 from the control unit 5, the cutoff signal 26 output from the latch circuit 29 becomes Lo. The second drive signal generation unit 39 calculates the logical product of the cutoff signal 42 and the control signal 28, and the drive signal 31 becomes Lo, so that the lower arm circuit 19 shown in FIG.

  In addition, as with the overcurrent protection device 120 shown in FIG. 2, the overcurrent protection device 120 shown in FIG. 6 inputs the cutoff signals 25 and 26 to the control unit 5 so that the control unit 5 is in the cutoff state and an overcurrent is generated. Can be detected. The overcurrent protection device 120 shown in FIG. 6 outputs the control signals 27 and 28 for turning off the semiconductor switching elements, that is, the Lo level control signals 27 and 28 after detecting the occurrence of the overcurrent. Thus, the entire inverter circuit 110 can be stopped.

  According to the overcurrent protection device 120 according to the second embodiment, only the lower arm circuit 19 stops when an overcurrent occurs regardless of the first determination value 34a, the second determination value 35a, t1, and t2. The motor 200 can be stably stopped.

Embodiment 3 FIG.
FIG. 7 is a diagram showing a configuration example of a converter device according to Embodiment 3 of the present invention. A converter device 300 illustrated in FIG. 7 includes a rectifier circuit 310 and an overcurrent protection device 120. The configuration of the overcurrent protection device 120 is the same as that of the overcurrent protection device 120 shown in the first embodiment or the second embodiment. The rectifier circuit 310 includes an upper arm circuit 18 and a lower arm circuit 19. The upper arm circuit 18 shown in FIG. 7 includes two semiconductor switching elements 6 and 7 and two diodes 12 and 13 connected in parallel to the semiconductor switching elements 6 and 7, respectively. The lower arm circuit 19 shown in FIG. 7 includes two semiconductor switching elements 9 and 10 and two diodes 15 and 16 connected in parallel to the semiconductor switching elements 9 and 10, respectively.

  A reactor 43 is provided between the connection point between the semiconductor switching element 6 and the semiconductor switching element 9 and the AC power supply 1. The capacitor 3 is connected between the output terminal of the upper arm circuit 18 and the output terminal of the lower arm circuit 19. The capacitor 3 is a smoothing capacitor that smoothes the DC voltage rectified by the upper arm circuit 18 and the lower arm circuit 19. The current detector 20 detects a current flowing into the lower arm circuit 19 from the negative side of the capacitor 3.

  The number of semiconductor switching elements constituting each of the upper arm circuit 18 and the lower arm circuit 19 is not limited to two, and the diodes 12, 13, 15, and 16 are connected to the semiconductor switching elements 6, 7, 9, and 10, respectively. A built-in parasitic diode may be used.

Converter device 300 operates as a booster or power factor correction circuit. The semiconductor switching element is turned ON / OFF by the drive signals 30 and 31 from the control unit 5, whereby the AC power supply 1 is short-circuited through the reactor 43 to accumulate energy in the reactor 43, and the accumulated energy is stored in the capacitor 3. When it is opened, boosting and power factor correction are performed.

  The control unit 5 outputs a control signal 27 for ON / OFF control of the upper arm circuit 18 to the first cutoff circuit 23. The output from the current detector 20 is input to the first filter circuit 21 and the second filter circuit 22.

  When the output of the first filter circuit 21 is input to the first cutoff circuit 23 and the first cutoff circuit 23 does not determine that the current is an overcurrent, the drive signal 30 becomes a drive signal similar to the control signal 27 and the first cutoff circuit 23 When the interruption circuit 23 determines that the current is an overcurrent, the drive signal 30 is interrupted. As a result, the operation of the upper arm circuit 18 is stopped.

  Similarly, the output of the second filter circuit 22 is input to the second cutoff circuit 24, and when the second cutoff circuit 24 does not determine an overcurrent, the drive signal 31 becomes a drive signal similar to the control signal 28, When the second cutoff circuit 24 determines that the current is overcurrent, the drive signal 31 is cut off. As a result, the operation of the lower arm circuit 19 is stopped. Since the overcurrent cutoff operation is the same as that of the first and second embodiments, the description thereof is omitted.

  According to the converter device 300 according to the third embodiment, as in the inverter device 100 according to the first and second embodiments, there is an effect that the semiconductor switching element can be protected from the overcurrent while preventing unnecessary operation of the overcurrent protection.

Embodiment 4 FIG.
FIG. 8 is a diagram showing a configuration example of an air conditioner according to Embodiment 4 of the present invention. The air conditioner 400 includes an indoor unit 410 and an outdoor unit 420 connected to the indoor unit 410. The indoor unit 410 is provided with a motor 200 as a drive source for the blower. The outdoor unit 420 is provided with a motor 200 as a drive source for the blower and a motor 200 as a drive source for the compressor. At least one of the indoor unit 410 and the outdoor unit 420 is provided with the inverter device 100 according to the first and second embodiments. The motor 200 provided in the indoor unit 410 and the outdoor unit 420 is driven by the inverter device 100.

  Note that converter device 300 according to Embodiment 3 is provided in at least one of indoor unit 410 and outdoor unit 420, and motor 200 is driven by an inverter circuit that converts a DC voltage output from converter device 300 into an AC voltage. Also good. By using the inverter device 100 according to the first and second embodiments or the converter device 300 according to the third embodiment, an air conditioner 400 that can protect an internal circuit from an overcurrent while preventing an unnecessary operation of the overcurrent protection can be realized. A highly reliable air conditioner 400 can be obtained.

  In the first to third embodiments, the upper arm circuit 18 is stopped when t1 elapses from the time when the output of the current detector 20 exceeds I1, and is decreased after elapse of t2 from the time when the output of the current detector 20 exceeds I2. Although the configuration example in which the arm circuit 19 is stopped has been described, the lower arm circuit 19 is stopped when the output of the current detector 20 exceeds I1, and the output of the current detector 20 exceeds I2 after t1 has elapsed. The upper arm circuit 18 may be stopped after t2. Since the lower arm circuit 19 is closer to the ground than the upper arm circuit 18, the potential is stable. Therefore, the semiconductor switching element constituting the lower arm among the upper and lower arms is less susceptible to noise and the like, and can be shut off and stopped stably.

  The configuration described in the above embodiment shows an example of the content of the present invention, and can be combined with another known technique, and can be combined with other configurations within the scope of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 AC power supply, 2 Rectifier, 3 Capacitor, 5 Control part, 6, 7, 8, 9, 10, 11 Semiconductor switching element, 12, 13, 14, 15, 16, 17 Diode, 18 Upper arm circuit, 19 Lower arm Circuit, 20 current detector, 21 first filter circuit, 22 second filter circuit, 23 first cutoff circuit, 24 second cutoff circuit, 25, 26 cutoff signal, 27, 28 control signal, 29 latch circuit , 30, 31 Drive signal, 32, 33 Comparator, 34 First determination value setting unit, 34a First determination value, 35 Second determination value setting unit, 35a Second determination value, 37 Logic circuit, 38 1st drive signal generation part, 39 2nd drive signal generation part, 40 reset signal, 41 and 42 interruption | blocking signal, 43 reactor, 100 inverter apparatus, 110 inverter circuit, 20 overcurrent protection device, 200 motor, 300 converter device, 310 rectifier circuit, 400 air conditioner, 410 indoor unit, 420 outdoor unit.

In order to solve the above-described problems and achieve the object, the overcurrent protection device of the present invention includes a current flowing through upper and lower arms configured by connecting a first semiconductor switching element and a second semiconductor switching element in series. A first filter circuit that filters the detected value with a first time constant, a second filter circuit that filters the detected value with a second time constant longer than the first time constant, and a first overcurrent A first determination value setting unit configured to set a determination value; and a second determination value setting unit configured to set a second overcurrent determination value smaller than the first overcurrent determination value. After the detection value exceeding the determination value is detected, after the first time constant has elapsed, the operation of the first semiconductor switching element is stopped, and the detection value exceeding the second overcurrent determination value is detected. After the elapse of the time constant of 2, the second semiconductor switching element Stop work from after the first time constant before the elapsed time constant of the second, when the detected value exceeds the first overcurrent determination value is not detected, the first semiconductor switching element and the second The operation of the semiconductor switching element is not stopped .

Claims (9)

A first filter circuit for filtering a detected value of a current flowing in an upper and lower arm configured by connecting a first semiconductor switching element and a second semiconductor switching element in series with a first time constant;
A second filter circuit for filtering the detected value with a second time constant longer than the first time constant;
A first determination value setting unit for setting a first overcurrent determination value;
A second determination value setting unit that sets a second overcurrent determination value that is smaller than the first overcurrent determination value;
After the first time constant has elapsed since the detection value exceeding the first overcurrent determination value is detected, the operation of the first semiconductor switching element is stopped,
An overcurrent protection device that stops the operation of the second semiconductor switching element after the second time constant has elapsed since the detection value exceeding the second overcurrent determination value is detected. An overcurrent protection device according to claim 1;
An inverter device comprising the upper and lower arms and an inverter circuit that converts a DC voltage into an AC voltage and outputs the AC voltage.   The inverter device according to claim 2, wherein the second semiconductor switching element is a semiconductor switching element constituting a lower arm of the upper and lower arms.   4. The inverter device according to claim 2, wherein the first semiconductor switching element and the second semiconductor switching element are formed of a wide band gap semiconductor.   The air conditioner provided with the inverter apparatus as described in any one of Claim 2 to 4. An overcurrent protection device according to claim 1;
A converter device comprising: a rectifier circuit that has the upper and lower arms and converts an AC voltage into a DC voltage and outputs the DC voltage.   The converter device according to claim 6, wherein the second semiconductor switching element is a semiconductor switching element constituting a lower arm of the upper and lower arms.   The converter device according to claim 5 or 6, wherein the first semiconductor switching element and the second semiconductor switching element are formed of a wide band gap semiconductor.   An air conditioner comprising the converter device according to any one of claims 6 to 8.

Images