JP4846646B2 - Contactless power supply - Google Patents

Description

  The present invention relates to a non-contact power feeding device, and in particular, a non-contact power feeding in which the load is leveled within the capability of the power feeding device, the power receiving part is downsized, the ground power supply equipment capacity is reduced, or the power feeding section length is increased. It relates to the device.

The output of the power receiving circuit of the non-contact power feeding device has a characteristic that the voltage decreases as the load power increases.
This is because the impedance of the secondary power receiving coil is generated due to a decrease in the efficiency of magnetic coupling due to the leakage magnetic flux between the primary power supply line and the secondary power receiving coil.
When the output power is increased by combining multiple power receiving circuits due to factors such as the positional relationship between the power receiving coil and the power supply line, coil temperature, and manufacturing dimension errors, the load is concentrated on the power receiving coil with a small power supply impedance. Therefore, an imbalance of power supplied to the load occurs between the power receiving coils.
In a circuit in which the load is concentrated, adverse effects such as an increase in heat generation, fuse blowing, and an increase in failure rate occur. Therefore, it is preferable to level the load.

In addition, when a capacitor input type rectifier circuit is connected to a series resonant circuit in which a power receiving coil and a load are connected in series and a resonant capacitor is connected between the power receiving coil and the load, if the capacitance of the smoothing capacitor is large, the secondary The load current flows through the resonance circuit only near the peak of the voltage induced in the coil.
The frequency of this current is three times, five times, seven times the frequency of the excitation current, and higher harmonic current components, but this harmonic current has high impedance at frequencies other than the resonance frequency of the series resonance circuit. Therefore, there is a drawback that the power of the power receiving coil cannot be used effectively, and the output power that can be extracted from the parallel resonance type power receiving circuit is reduced.

  The present invention has as its first object to provide a non-contact power feeding device capable of leveling a load even if the state of each power receiving coil is different in view of the problems of the conventional non-contact power feeding device. A second object is to efficiently supply power to the load by bypassing the harmonic current.

In order to achieve the above object, a non-contact power feeding device of the present invention has a plurality of power receiving coils, a resonance circuit, a rectifier circuit, and a voltage stabilizing circuit for each power receiving coil, and outputs each voltage stabilizing circuit. in the non-contact power feeding apparatus that bind, to a voltage stabilizing circuit, Rutotomoni, the resonant circuit of each receiving coil to have a drooping characteristic which decreases in proportion to the constant output current or voltage in the output current, the rectifier circuit And a harmonic bypass capacitor connected in parallel .

  According to the non-contact power feeding device of the present invention, the power receiving coil has a plurality of power receiving coils, and each power receiving coil has a resonance circuit, a rectifier circuit, and a voltage stabilizing circuit, and combines outputs of the voltage stabilizing circuits. In the non-contact power supply device, the voltage stabilizing circuit has a drooping characteristic in which the voltage drops in proportion to the output current at a certain output current or more, so that the power received from each receiving coil can be leveled. As a result, it is possible to prevent the concentration of the load on a part of the circuits and to prevent adverse effects such as an increase in heat generation, a fuse blown, and an increase in failure rate.

In particular , by connecting a harmonic bypass capacitor in parallel to the rectifier circuit to the resonance circuit of each power receiving coil, the fundamental current flowing in the resonance circuit is increased relative to the harmonic current flowing in the rectifier circuit, thereby stabilizing the feed power Can be made.

  Hereinafter, embodiments of the non-contact power feeding device of the present invention will be described with reference to the drawings.

FIG. 1 shows the structure of the power receiving coil of the non-contact power feeding device.
The feeder 3 is supported by the feeder support 4 and power is transmitted to the power receiving coil on the moving body side.
The power receiving coil winds the secondary winding 2 of the coil around the ferrite core 1 and converts the magnetic flux induced in the ferrite core 1 into a current. This structure is known.

FIG. 2 shows a schematic configuration of the resonance circuit of the present embodiment.
The feed line 3 is excited by a high frequency power source 5, and the magnetic flux is converted into a current by the power receiving coil 6.
The resonance capacitor 7 connected in series with the power receiving coil 6 sets the resonance capacitor so as to resonate in series with the frequency of the high frequency power supply by the inductance viewed from the secondary side of the power receiving coil 6 and the capacitance of the resonance capacitor 7.
The resonated electromotive force is rectified by a full-wave rectifier circuit of a rectifier diode 9 and smoothed by a smoothing capacitor 10 to a DC voltage with less pulsation.

When a load is connected to this circuit, as shown in FIG. 3, the rectified voltage (in other words, the output voltage of the resonant circuit) Er applied to the rectifier circuit becomes a sine wave, but the current Ir of the rectifier circuit is the maximum value of the rectified voltage. A steep current flows only in the vicinity, and this becomes more prominent as the capacity of the smoothing capacitor 10 increases.
Focusing on the frequency included in the rectified current, in addition to the fundamental wave component that is the same as the frequency of the high-frequency power supply, there are many odd-order harmonic components such as three times, five times, and seven times the fundamental wave.
On the other hand, the resonance circuit has a high impedance with respect to higher harmonics higher than the resonance frequency, and acts to block harmonic current.

Therefore, a harmonic bypass capacitor 8 is connected in parallel with the rectifier circuit.
In the harmonic bypass capacitor 8, the fundamental wave component that becomes the dominant factor in the power transmission from the primary to the secondary of the power receiving coil 6 flows from the rectifier circuit to the load through the power receiving coil 6 and the resonance circuit, and the harmonic component is A path that passes through the wave bypass capacitor 8 and flows from the rectifier circuit to the load is formed.
As the capacity of the harmonic bypass capacitor 8, a capacity of about 10 to 20% of the resonance capacitor is selected. Thereby, the power receiving efficiency when the capacity of the smoothing capacitor is large is improved.

The harmonic bypass capacitor 8 has a slight influence on the resonance frequency of the series resonance circuit, and since the capacitance is fixed, the resonance frequency change can be easily corrected.
When there is no harmonic bypass capacitor, the harmonic bypass capacitor 8 shows a low impedance only in the vicinity of the resonance frequency due to the resonance characteristic with a sharp power supply impedance viewed from the rectifier circuit. However, by adding the harmonic bypass capacitor 8, The higher harmonic current flows from the harmonic bypass capacitor 8 to the rectifier circuit, so that the power source impedance viewed from the rectifier circuit is lowered even for frequencies higher than the resonance frequency.
By facilitating the flow of high-order harmonic current, the fundamental wave current that is the output of the high-frequency power source can also flow easily, and power is efficiently transmitted to the secondary side.

On the other hand, in a large-scale non-contact power feeding device, a plurality of power receiving coils are used, and a large amount of electric power is taken out by a moving body. This configuration is shown in FIG.
The power receiving coils 11, 12, 13, 14 are excited by a power supply line connected to a high frequency power source. Resonant / rectifier circuits 15, 16, 17, and 18 described with reference to FIG. 2 are connected to each power receiving coil, and voltage stabilizing circuits 19, 20, 21, and 22 are connected to the output of the rectifier circuit.
The outputs of the respective voltage stabilization circuits are coupled by coupling diodes 23, 24, 25, and 26.

As shown in FIG. 5, the relationship between the output voltage and the output current of the resonance circuit including each power receiving coil does not necessarily match all the outputs even when the excitation current is constant.
That is, the value varies depending on a plurality of factors such as the magnetic permeability of the ferrite core of the power receiving coil, the positional relationship between the power supply line and the power receiving coil, the temperature, the inductance error of the secondary coil winding, and the capacitance error of the resonance capacitor.
The impedance of the power supply viewed from the rectifier circuit is the reciprocal of the voltage / current gradient shown in FIG.

Unlike a general switching power supply, the voltage stabilization circuit has a drooping characteristic in which the voltage drops in proportion to the output current above a certain output current.
This voltage stabilization circuit is equivalent to a circuit as shown in FIG.
The internal resistances Rc1, Rc2, Rc3, and Rc4 of the power supply have different unique values for each power receiving coil system. Since the voltage stabilizing circuit acts as a constant voltage power source when the load current is small, the output impedances Rd1 to Rd4 are zero. Above a certain current, Rd1 to Rd4 have a certain resistance because the voltage drops in proportion to the current.

For example, when the power supply device can supply 10 kW of power in each power receiving coil system and the internal resistance Rc for each system is about Rc = 1.5 to 2.0Ω, the drooping characteristic is 0.2 to 0.5Ω. To have.
These two are connected in series between the power source and the load, and variations in the power source impedance can be reduced or set to the same value.

  In a system with a relatively small power supply capacity of about several kW, the Rc value is large, from several Ω to 10 Ω, so the effect is small. However, in a system of 10 kW or more, the configuration of this embodiment is efficient and the load can be balanced. Power supply device.

In the present embodiment, the resonance is described as series resonance, but the harmonic bypass capacitor 8 is meaningless in a parallel resonance circuit, but each receiving coil can be leveled by the drooping characteristics of the voltage stabilization circuit. .
Moreover, although the present Example demonstrated by the parallel connection of four receiving coils, it is not limited to this, It can apply to two or more parallel connections.

  As mentioned above, although the non-contact electric power feeder of this invention was demonstrated based on the Example, this invention is not limited to the structure described in the said Example, The structure is suitably changed in the range which does not deviate from the meaning. Can be changed.

  The non-contact power feeding device of the present invention has a characteristic of preventing concentration of loads on some circuits by leveling power received from a plurality of power receiving coils. For example, it can be suitably used in a transport device that minimizes dust generation in a clean room.

It is sectional drawing which shows one Example of the non-contact electric power feeder of this invention, and shows a feeder and a receiving coil. It is a figure which shows the resonance circuit of the non-contact electric power feeder. It is a graph which shows the rectification voltage and rectification current of a resonance circuit without a harmonic bypass capacitor. It is a circuit diagram which shows an example of the non-contact electric power feeder which uses a several receiving coil and takes out big electric power with a moving body. It is a graph which shows the relationship between the output voltage and output current of a resonance circuit. It is a graph which shows the relationship between the output voltage and output current of a stabilization circuit. It is a circuit diagram which shows the Example of a voltage stabilization circuit.

DESCRIPTION OF SYMBOLS 1 Ferrite core 2 Secondary winding 3 Feed line 4 Feed line support material 5 High frequency power supply 6 Receiving coil 7 Resonance capacitor 8 Harmonic bypass capacitor 9 Rectifier diode 10 Smoothing capacitor 11-14 Receiving coil 15-18 Resonance / rectifier circuit 19 ~ 22 Voltage stabilization circuit 23-26 Coupling diode

Claims (1)

In a non-contact power feeding device having a plurality of power receiving coils and having a resonance circuit, a rectifying circuit and a voltage stabilizing circuit for each power receiving coil, and connecting the outputs of the voltage stabilizing circuits, the voltage stabilizing circuit , Rutotomoni to have a drooping characteristic which decreases in proportion to the constant output current or voltage in the output current, the resonant circuit of each receiving coil, and wherein the connected harmonic bypass capacitor in parallel with the rectifier circuit Non-contact power feeding device.

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