JP2009254031A - Non-contact feeder device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-contact feeder device which suppresses both a loss of an exciting current generated by a primary-side feeder line and the generation of a voltage of a secondary-side power receiving circuit, is reduced in energy loss, small in size, and low in price. <P>SOLUTION: In the non-contact feeder device which feeds power to a transportation vehicle from ground equipment by electromagnetic induction in a non-contact manner, the feeder device comprises a high-frequency power supply device 2 which reduces the primary-side excitation current flowing to a feeder passage when a load is light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-contact power supply apparatus that supplies power to a transport vehicle in a non-contact manner in a clean room such as a semiconductor or a liquid crystal factory.

When power is supplied to the load in a non-contact manner, if an excitation current is passed through the power supply line at a constant voltage, the current flowing through the line decreases due to the inductance when the line length of the power supply line increases.
For this reason, normally, control that makes the effective value of the excitation current constant is performed by an inverter circuit that supplies the excitation current.

When power is supplied to a large-sized device by non-contact power supply, Joule heat loss is caused by the electrical resistance of the power supply line proportional to the line length of the power supply line and the excitation current.
This power is not preferable from the viewpoint of energy saving, even when there is a loss of several percent when power is supplied at about 100 kW, even if there is a loss of several percent.

It is well known that the voltage generated in the secondary circuit is proportional to the excitation current.
If the excitation current is not a completely constant alternating current but a fluctuating current with amplitude modulation applied, in the secondary power receiving circuit, the voltage of the smoothing circuit that rectifies the generated voltage fluctuates at light loads. The smoothing capacitor is charged with the maximum voltage of, so that the circuit voltage of the smoothing circuit increases.
When the generated voltage at the light load is higher than the generated voltage at the rated load, the withstand voltage of the electronic components used in the secondary circuit is designed to match the voltage at the light load or no load at which the voltage increases most There are disadvantages that increase the cost of parts and increase the size of the apparatus.

  In view of the problems of the above-described conventional non-contact power feeding device, the present invention suppresses both the excitation current loss caused by the primary side feed line and the voltage generated by the secondary side power receiving circuit, and is small and inexpensive with little energy loss. An object of the present invention is to provide a non-contact power feeding device.

  In order to achieve the above object, a non-contact power feeding device according to the present invention is a non-contact power feeding device that feeds power from a ground facility to a transport vehicle in a non-contact manner by electromagnetic induction. Is provided with a high-frequency power supply device that reduces the load when the load is light.

  In this case, the high frequency power supply device is reduced based on the product of the reduction coefficient corresponding to the DC power passing through the smoothing circuit of the inverter circuit that supplies the primary side excitation current and the average value or effective value of the output current. The output current of the primary side excitation current to be determined can be determined.

  In addition, the high frequency power supply device can determine the output current of the primary side excitation current to be reduced by comparing the maximum value of the output current with the reference value that is the control target value.

According to the non-contact power feeding device of the present invention, in a transport facility that feeds power from a ground facility to a transport vehicle by electromagnetic induction in a non-contact manner, the primary side excitation current that flows through the feed line is reduced when the load is light. By providing a high-frequency power supply that reduces the primary side excitation current at light load, both the loss of the excitation current due to the feed line length and the voltage generated by the secondary side power receiving circuit are reduced, and the energy loss is reduced. A small, inexpensive and non-contact power feeding system can be constructed.
Note that the non-contact power feeding device of the present invention has zero or one device simultaneously entering the power feeding section that the inverter circuit is responsible for when one large device, for example, a stacker crane is moved by one high-frequency power device. The effect can be demonstrated by the operation of about 2 units at most.
In applications where power is supplied to a large number of small transport vehicles, when only one transport vehicle is in the power supply section, there is a problem that the specified power cannot be obtained with the excitation current reduced. Therefore, it is not suitable for operating a system that supplies a large number of power supplies.

  In addition, the high-frequency power supply device 1 reduces based on the product of the reduction coefficient corresponding to the DC power passing through the smoothing circuit of the inverter circuit that supplies the primary excitation current and the average value or effective value of the output current. By determining the output current of the secondary side excitation current, an arbitrary reduction coefficient can be selected so that the effective value can be further reduced in the light load state.

  In addition, the high frequency power supply device determines the output current of the primary side excitation current to be reduced by comparing the maximum value of the output current with the reference value that is the control target value, thereby reducing the active power consumed by the load. The output current is controlled to a constant maximum value, and the effective value is decreased by the amount of fluctuation of the output current in a light load state.

  Embodiments of a non-contact power feeding device according to the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of the non-contact power feeding device of the present invention.
This non-contact power feeding device feeds electric power from ground equipment to a transport vehicle in a non-contact manner by electromagnetic induction, and a high-frequency power source device 2 that reduces the primary side excitation current flowing through the feed line when the load is light. It has.

As shown in FIG. 1, the high-frequency power supply device 2 includes a rectifier circuit 3 that varies a rectified voltage by phase control of a thyristor, a smoothing capacitor 4, and an inverter circuit 5 that generates high-frequency alternating current using a switching element such as an IGBT, A smoothing circuit voltage signal 7, a smoothing circuit current signal 8, an output voltage signal 9 and an output current signal 10 are inputted, and a control circuit 6 for generating a gate drive signal for phase control of the thyristor and an IGBT gate drive signal. It is comprised by.
The high frequency power supply device 2 is supplied with power by an AC power source 1 such as a three-phase AC.
On the other hand, on the output side of the high frequency power supply device 2, capacitors 11 and 12 that compensate for the inductive impedance of the feed line 13 are arranged in a distributed manner for each constant feed line length.

FIG. 2 shows a waveform of the output current of the high frequency power supply device.
Ideally, a high-frequency alternating current with a constant output current flows, but the output current varies due to a plurality of factors.
The most significant factor is the ripple voltage of the smoothing circuit generated by the current control response time of the high frequency power supply device 2 and the frequency relationship of the AC power supply 1.
When the high-frequency power supply device 2 is formed by a phase control rectifier circuit 3 and a variable voltage is generated, and the inverter circuit 5 is a square wave inverter that performs switching at a phase of every 180 degrees in one cycle of the high-frequency current, For the capacity of 4, the time constant is set shorter than the response time of the current control.
If the time constant of the smoothing circuit is large, the time constant of the smoothing capacitor 4 enters the feedback loop of the current control and a control delay occurs, so that the current control cannot be performed normally.

On the other hand, the AC power source 1 is a 50 Hz or 60 Hz power source, and when this three-phase AC is full-wave rectified, a ripple occurs at a frequency five times the power frequency. In an alternating current of 60 Hz, a ripple of 300 Hz occurs.
When the inverter circuit 5 is driven by the DC current of the smoothing circuit including the ripple, the output current has a waveform that is amplitude-modulated at 300 Hz, which is five times the power supply frequency, as shown in FIG.

  As another variation factor, when the power of the load and the inductance of the load are caused by the load state of the transport vehicle or the movement of the transport vehicle, the load state viewed from the high frequency power supply device 2 is very close to the resonance state, so that the current control follows. It may fluctuate without being limited.

When paying attention to the transport vehicle, the entire system configuration is as shown in FIG.
A primary side excitation current is passed through the feed line 13 by the high frequency power supply device 2. Impedance compensating capacitors 11 and 12 are distributed in the middle of the feeder line 13.
In the transport vehicle, the electromotive force induced by electromagnetic induction in the power receiving coil 14 is resonated by the resonance capacitor 15, rectified by the rectifier circuit 16, and supplied to the load circuit 17.
In addition, when the load of a conveyance vehicle cannot be supplied only with the electric power of one receiving coil 14, the output of the rectifier circuit of several receiving circuit is connected in parallel, and required electric power is supplied suitably.

It is well known that the voltage generated by the power receiving coil 14 input to the rectifier circuit 16 is proportional to the current flowing through the feed line 13.
When the load on the transport vehicle is small or zero, the voltage of the rectifier circuit 16 charges the smoothing capacitor of the rectifier circuit 16 with the maximum value of the voltage generated by the power receiving coil 14.
In a sinusoidal alternating current with a constant amplitude, the crest factor (CrestFactor) indicating the ratio between the maximum value and the effective value of the waveform is 1.4.
However, when the current fluctuates as shown in FIG. 2, the crest factor increases to about 1.8 to 2.0 with a larger value.
In the case of a power receiving circuit in which the voltage generated by the secondary circuit is 200 V as an effective value, a smoothing capacitor that charges only up to 280 V when the amplitude is constant charges at 400 V at a crest factor of 2.0.
The aluminum electrolytic capacitor used for the smoothing capacitor becomes larger and costs higher if the withstand voltage is increased for the same capacitance.

FIG. 4A shows the relationship between the effective value and the maximum value of the output current in the case of constant current control.
The effective value of the output current is controlled to be almost constant. This is a result of the control target value being controlled by the effective value.
On the other hand, the maximum value of the output current varies because it is not a controlled variable. When the load is small, the inverter output is in a resonance state, the resistance of the real part of the impedance becomes a very large value, and the imaginary part becomes small.
For this reason, it becomes easy to vibrate and becomes unstable, and in addition to continuing the vibration, a ripple that is five times the power supply frequency vibrates because it is superimposed on the DC power supply that is supplied to the inverter circuit. Increases the maximum value.

  In the present embodiment, the current control method includes current control using the average value of the output current shown in FIG. 3A and the average power of the DC portion of the smoothing circuit, and the maximum load current shown in FIG. Two types of current control by value are proposed.

The control by the maximum value of the load current shown in FIG. 3 (b) detects the output current of the inverter circuit, that is, the current of the feeder line, and within a certain time of this current, for example, the maximum value in the time range of 10 milliseconds, A reference value serving as a control target value is compared, and a current command is generated through the PID controller.
In the configuration of the high-frequency power supply device 2 shown in FIG. 1, the current is controlled by a thyristor gate signal that controls the flow angle of the rectifier circuit 3, and when the output current is large, the ignition of the thyristor is delayed. Reduce the rectified DC voltage by reducing the angle.
On the other hand, when the output current is small, a series of control is performed in which the thyristor is fired earlier, the flow angle is increased, and the DC voltage is increased.
When this control is performed, the output current with respect to the active power consumed by the load is controlled to a constant maximum value as shown in FIG. 4B, and the effective value is the amount that the output current fluctuates in a light load state. Only decrease.

The method shown in FIG. 3A shows current control using three of the current flowing from the smoothing circuit to the inverter circuit 5, the voltage of the smoothing circuit, and the output current of the inverter circuit 5.
Since the smoothing circuit is a DC circuit, its DC power is the product of current and voltage. Each detected signal is filtered by a low-pass filter to remove high frequency components outside the control response range.
As for the signal processing method, an average value can be easily obtained by a general low-pass filter process, regardless of whether it is a filter process based on electrical signal processing or a filter process based on CPU processing after A / D conversion of a signal. .
For example, methods such as a Butterworth filter are generally used for analog processing and an FIR filter or moving average is used for CPU calculation processing.
The power of the smoothing circuit is the power of the power supply line including the conversion loss of the inverter circuit 5, but the conversion efficiency of the inverter circuit 5 is a fixed frequency square wave inverter, and a full-bridge IGBT is ignited every 180 degrees. In the case of repetition, the efficiency of about 98% can be realized at a frequency in the vicinity of 10 kHz, so the conversion loss of the inverter is ignored.
A reduction coefficient for the power value of the smoothing circuit is set by a linear function, and a product with a reference value is obtained. The product value is compared with the load current as a reference value of the current command, and feedback control is performed.
In this control, as shown in FIG. 4C, since the reduction rate is set with respect to the maximum value, an arbitrary reduction factor can be selected so that the effective value can be further reduced in a light load state. .

In a non-contact power supply device, when a power supply device supplies power to one transport vehicle, a specified excitation current flows through the power supply line with the rated load, that is, the active power shown in FIG. Accordingly, the rated power can be supplied, and the excitation current can be reduced in the entire region in the power region below the rated power.
When supplying power to two transport vehicles, one unit may require no load, and one unit may require rated power, and the excitation current can be reduced in an area that is 1/2 or less of the effective power. It is.
Similarly, when there are N transport vehicles, it can be reduced in a region of 1 / N or less.
Therefore, when the number of transport vehicles is large, that is, in an application in which a large number of small transport vehicles are moved by one large power source, the range in which the excitation current can be reduced becomes small.
Practically, it is possible to provide suitable control in the case of two or less transport vehicles.

Since the Joule heat loss of the feed line is proportional to the electrical resistance of the feed line and the square of the current flowing through the feed line, the Joule heat loss can be effectively reduced by reducing the excitation current flowing through the feed line in the light load region. It is possible to reduce non-contact power feeding with light load and low power loss.
In addition, by reducing the voltage generated in the secondary power receiving circuit at light load, the withstand voltage of the electronic components to be used can be lowered, and a small and inexpensive non-contact power feeding system can be constructed.

  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 contactless power supply device of the present invention reduces the excitation current on the primary side at a light load, thereby suppressing both the loss of the excitation current caused by the power supply line on the primary side and the voltage generated by the secondary side power receiving circuit. Therefore, it can be used widely and suitably as a small and inexpensive non-contact power feeding device with little energy loss.

It is a block diagram which shows one Example of the high frequency power supply device of the non-contact electric power supply of this invention. It is a graph which shows the waveform of the output current of a high frequency power supply device. The current control method of the high-frequency power supply device is shown, (a) is a block diagram when constant current control is performed with the average value of the output current and the power of the smoothing circuit, and (b) is constant current control with the maximum value of the output current. It is a block diagram at the time of going. The relationship between the effective value and the maximum value of the output current in the constant current control is shown. (A) is a graph when the constant current control is performed with the average value or the effective value of the output current, and (b) is the maximum value of the output current. A graph when the constant current control is performed, (c) is a graph when the constant current control is performed with the average value of the output current and the power of the smoothing circuit. It is a block diagram which shows the whole structure of a non-contact electric power feeder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 High frequency power supply device 3 Rectifier circuit 4 Smoothing capacitor 5 Inverter circuit 6 Control circuit 7 Voltage signal of smoothing circuit 8 Current signal of smoothing circuit 9 Output voltage signal 10 Output current signal 11 Capacitor 12 Capacitor 13 Feeding line 14 Power receiving coil 15 Resonant capacitor 16 Rectifier circuit 17 Load circuit

Claims (3)

  In a non-contact power feeding device that feeds electric power from a ground facility to a transport vehicle by electromagnetic induction in a non-contact manner, a high-frequency power source device is provided that reduces the primary-side excitation current that flows through the feed line when the load is light. A non-contact power feeding device.   The high frequency power supply apparatus reduces the primary side based on the product of the reduction coefficient corresponding to the DC power passing through the smoothing circuit of the inverter circuit that feeds the primary side excitation current and the average value or effective value of the output current. The non-contact power feeding apparatus according to claim 1, wherein an output current of the exciting current is determined.   The high-frequency power supply apparatus determines the output current of the primary side excitation current to be reduced by comparing the maximum value of the output current with a reference value that is a control target value. Non-contact power feeding device.

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