JP2012023913A - Non-contact power feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stable power supply by preventing receiving-side power from excessively decreasing when a relative position between a magnetic core of a power feeding part and that of a power reception part in a non-contact power feeding device shifts.SOLUTION: A power feeding part 2 includes: a driver 25 that supplies a high-frequency signal for driving to a resonance circuit 28; a frequency variable oscillation circuit 26 that adjusts a frequency of the high-frequency signal; and current detection means (current transformer 33 and ammeter 34) that detects a current value of the high-frequency signal. When a distance between a magnetic core 31 of the power feeding part 2 and a magnetic core 54 of a power reception part 5 is shifted from a predetermined value, a frequency of a high-frequency signal for driving a resonance circuit 28 of the power feeding part 2 is shifted in response to a resonance frequency of a resonance circuit 51 of a power reception part 5, and thereby the resonance circuits 27 and 51 are harmonized with each other to transmit power with optimum efficiency.

Description

  The present invention relates to a non-contact power supply device that supplies power in a non-contact manner to a power receiving unit mounted on an automatic guided vehicle from a power supply unit installed outdoors or indoors by using electromagnetic induction coupling between coils.

  As a method for charging the battery of the automatic guided vehicle, a contact type or a connector type has been mainly adopted, but in recent years, a method using a non-contact power feeding device has been adopted. In this method, power is supplied (powered) to the secondary coil of the power receiving unit mounted on the automatic guided vehicle from the primary coil of the power supply unit installed in the power supply stand in a non-contact manner, and driving power is supplied to the battery. It is something to store. Here, “non-contact” means that there is no physical contact by a connector or a pantograph.

  When the non-contact power feeding device is used to charge the battery, the automatic guided vehicle travels autonomously on a predetermined track and then stops at the charging standby position where the power feeding unit is installed. At this position, the primary coil of the power feeding unit and the secondary coil of the power receiving unit (automated guided vehicle) face each other with a predetermined distance therebetween. When a high frequency current is passed through the primary coil of the power feeding unit at the charging standby position, an electromotive force is generated in the secondary coil of the power receiving unit by electromagnetic induction, and the power is transmitted.

  At this time, a radio wave (electromagnetic wave) is emitted from the primary coil. Even in an electric device using a non-contact power supply device, when power to be supplied is small, such as an electric toothbrush or an electric shaver, the intensity of the emitted radio wave is very weak, so no special measures need be taken. On the other hand, if the power supplied using a non-contact power supply device is large, such as an automated guided vehicle, an application for permission to install a radio station is required, and in order to avoid effects on the human body, The strength must be kept below the regulation value.

  In the case of the automatic guided vehicle, the power feeding unit of the non-contact power feeding device is opened so as not to prevent the automatic guided vehicle from moving. Therefore, in order to set the intensity of the radio wave emitted from the primary coil of the power feeding unit to a value equal to or less than the regulation value, the radio wave emitted from the primary coil when the automatic guided vehicle is at the charging standby position is blocked by the shielding means. Need to be shielded. However, providing the shielding means is not preferable because it leads to an increase in the cost of the non-contact power feeding device.

  In order to prevent the non-contact power supply device from being restricted by the Radio Law, it is conceivable that the frequency of the current flowing through the primary coil of the power supply unit is less than 10 kHz. There is a need to.

  The following two configurations are known as the configuration of the power conversion unit of the non-contact power supply apparatus. In the first configuration (see, for example, Patent Document 1), a pair of power feeding units and power receiving units each having a coil wound in a spiral shape are arranged close to each other so that the axes of the coils coincide with each other. On the other hand, in the second configuration (see, for example, Patent Document 2), a pair of a power feeding unit and a power receiving unit each having a coil wound around a U-shaped or C-shaped magnetic core are arranged so that the respective magnetic cores face each other. It is arranged.

  In both the first and second configurations, a resonance circuit including a coil and a capacitor is provided in the power supply unit and the power reception unit, and the resonance frequency of both the resonance circuits is set to be close to each other. Are resonated at the same frequency to efficiently transmit power from the power feeding unit to the power receiving unit.

JP 2003-61881 A JP 2001-110658 A

  When the first configuration is adopted for the power conversion unit, when the frequency of the current flowing through the primary coil becomes less than 10 kHz, the diameter of each coil is significantly increased, and it is difficult to attach the secondary coil to the automatic guided vehicle. .

  On the other hand, when the second configuration is adopted, the sizes of the power feeding unit and the power receiving unit hardly change depending on the frequency value. However, if the positions of the magnetic cores of the power feeding unit and the power receiving unit are shifted, the resonance frequency of the power receiving unit is changed by changing the inductance of the power conversion unit, and the resonance circuit of the power feeding unit and the resonance circuit of the power receiving unit are tuned. become unable. As a result, the output of the power receiving unit is extremely reduced, and sufficient power cannot be stably supplied.

  The automatic guided vehicle is adjusted so as to always stop at the same position (charging standby position) by controlling a motor that drives a handle or wheels. However, it is difficult to accurately stop at the same position every time due to the load of the automatic guided vehicle, the accuracy of the position sensor, and the like. For this reason, every time the operation is stopped, a slight shift occurs in the positions of the magnetic cores of the power supply unit and the power reception unit, and the resonance circuit of the power supply unit and the resonance circuit of the power reception unit cannot be tuned.

  It is an object of the present invention to provide a non-contact power feeding device capable of preventing power on the power receiving side from being extremely lowered and stably supplying power even when the positions of the magnetic cores of the power feeding unit and the power receiving unit are shifted. Objective.

To achieve the above object, a non-contact power feeding device according to the present invention is a non-contact power feeding device that supplies power of a power feeding unit to a power receiving unit in a non-contact manner using electromagnetic induction,
The power feeding unit is
A first resonant circuit including a first magnetic core, a first coil wound around the first magnetic core, and a first capacitor;
A first rectifying and smoothing circuit for converting AC power supplied from the outside into DC power;
A driver that generates a high-frequency signal for driving the first resonance circuit based on DC power supplied from the first rectifying and smoothing circuit;
A variable frequency transmission circuit for adjusting the frequency of the high frequency signal generated by the driver;
Current detection means for detecting a current value of a high-frequency signal output from the driver;
A control circuit for controlling the oscillation frequency of the frequency variable oscillation circuit based on the current value detected by the current detection means,
The power receiving unit
A second magnetic core, a second coil wound around the second magnetic core, and a second resonance circuit including a second capacitor;
Power is transmitted from the first coil of the power feeding unit to the second coil of the power receiving unit by utilizing resonance between the first resonance circuit and the second resonance circuit.

  Here, a core formed of a U-shaped magnetic body is used as the first magnetic core and the second magnetic core, and the first magnetic core and the second magnetic core are connected to each other at both ends. It is preferable to arrange the end faces to face each other.

  The current detection means is preferably composed of a current transformer attached to the output-side wiring of the driver and an ammeter that detects the output current of the current transformer.

  Moreover, it is preferable that the said electric power feeding part is further provided with the voltage variable part which adjusts the value of the voltage of the alternating current power supplied from the said outside. Moreover, it is preferable that the said power receiving part is further provided with the rectification smoothing circuit which converts the alternating current power transmitted to the said 2nd resonance circuit into direct current power.

  Further, it is preferable that the first coil and the first capacitor are connected in parallel, and the second coil and the second capacitor are connected in series.

  When the resonance frequency of the resonance circuit of the power receiving unit changes with the displacement of the magnetic core between the power feeding unit and the power receiving unit, the resonance circuit of the power feeding unit resonates with the power receiving unit by changing the frequency of the current flowing through the primary coil. As a result, power can be transmitted from the power feeding unit to the power receiving unit with optimum efficiency.

It is a block diagram which shows the structure of the non-contact electric power feeder concerning embodiment of this invention. It is the figure which showed schematically the structure of the electric power transmission part among the structures of FIG. It is a figure which shows the example of a measurement of the transmission output and reception output when the space | interval d of the magnetic core of a electric power feeding part and the magnetic core of a receiving part changes. When the distance d between the magnetic core of the power feeding unit and the core of the power receiving unit is changed, the frequency (solid line) of the driving signal of the power feeding unit when the transmission output and the reception output show a peak, and the reception of the power receiving unit It is a figure which shows the example of a measurement of an output (broken line).

  Hereinafter, the non-contact power feeding device of the present invention will be described with reference to the drawings. In FIG. 1, the structure of the non-contact electric power feeder concerning embodiment of this invention is shown. The non-contact power supply apparatus 1 includes a power supply unit 2 installed in a power supply stand provided in a factory or the like, and a power reception unit 3 mounted on an automatic guided vehicle.

  The power feeding unit 2 includes a voltage variable unit 21, a rectifying / smoothing circuit 22, a driver 25, a variable frequency oscillation circuit 26, a reactor 27, a resonance circuit 28, a control circuit 32, a current transformer 33, an ammeter 34, a light receiver 35, and an AC−. A DC converter 36 is included. On the other hand, the power receiving unit 5 includes a resonance circuit 51, a rectifying / smoothing circuit 55, a load 58, and a projector 59.

<Principle of power transmission and frequency adjustment of driving signal>
Before describing the configuration and operation of the power feeding unit 2 and the power receiving unit 5, the principle of power transmission from the power feeding unit 2 to the power receiving unit 5 and the frequency adjustment of the driving signal of the power feeding unit 2 will be described.

  The power feeding unit 2 includes a resonance circuit 28 in which a coil 29 and a capacitor 30 are connected in parallel, a driver 25 that supplies a driving high-frequency signal to the resonance circuit 28, and a frequency variable transmission circuit that adjusts the frequency of the driving high-frequency signal. 26. On the other hand, the power receiving unit 3 includes a resonance circuit 51 in which a coil 52 and a capacitor 53 are connected in series.

  The driver 25 of the power feeding unit 2 is operated in advance at a frequency set so that the resonance frequency of the resonance circuit 28 of the power feeding unit 2 is close to the resonance frequency of the resonance circuit 51 of the power receiving unit 5. Then, the resonance circuit 28 of the power supply unit 2 and the resonance circuit 51 of the power reception unit 5 resonate at substantially the same frequency, and power is efficiently transmitted from the power supply unit 2 to the power reception unit 5.

  FIG. 2 schematically shows the configuration of the power transmission unit composed of the magnetic core 31 arranged in the power feeding unit 2 and the magnetic core 54 arranged in the power receiving unit 5 in the configuration of FIG. is there. The U-shaped magnetic core 31 of the power feeding unit 2 around which the coil 29 is wound and the U-shaped magnetic core 54 of the power receiving unit 5 around which the coil 52 is wound are arranged so as to face each other with a predetermined distance d. Has been.

  When an alternating current flows through the coil 29 of the power feeding unit 2 due to resonance, the magnetic flux generated by the coil 29 and the magnetic core 31 changes, and an electromotive force is induced in the coil 52 of the power receiving unit 5 according to the same principle as that of the transformer. As a result, electric power is transmitted from the power feeding unit 2 to the power receiving unit 5 in a contactless manner.

  In this Embodiment, the case where the non-contact electric power feeder 1 is used for the electric power feeding of an automatic guided vehicle is assumed. In this case, the power feeding unit 2 is installed in a power feeding stand in a factory or the like, and the power receiving unit 5 is mounted on an automatic guided vehicle. As described above, the automatic guided vehicle is adjusted to always stop at the same position (charging standby position) by controlling the motor.

  In the charging standby position, as shown in FIG. 2, the automatic guided vehicle stops at a position where the magnetic core 31 of the power feeding unit 2 faces the magnetic core 54 of the power receiving unit 5. However, it is difficult to stop at the same position every time due to the load of the automatic guided vehicle and the accuracy of the position sensor. For this reason, every time the vehicle stops, there is a slight shift in the relative position of the magnetic core 54 of the power receiving unit 5 with respect to the magnetic core 31 of the power feeding unit 2.

  As described above, the frequency of the high-frequency signal for driving the resonance circuit generated by the driver 25 of the power feeding unit 2 is set to a value that substantially matches the resonance frequency of the power receiving unit 5. When the resonance circuit 27 of the power feeding unit 2 and the resonance circuit 51 of the power receiving unit 5 resonate at this frequency, power is most efficiently transmitted from the power feeding unit 2 to the power receiving unit 5.

  FIG. 3 shows a measurement example of the transmission output and the reception output when the distance d between the magnetic core 31 and the magnetic core 54 changes. In the figure, the vertical axis indicates the transmission output of the power feeding unit 2 and the reception output of the power receiving unit 5. The horizontal axis indicates the distance d between the magnetic core 31 and the magnetic core 54.

  In FIG. 3, “at the time of 10 mm peak” means a transmission output (dashed line) when the distance d changes in the non-contact power feeding device 1 set so that the resonance circuits 28 and 51 resonate when the distance d is 10 mm. And the received output (solid line). “At 15 mm peak”, in the non-contact power feeding device 1 set so that the resonance circuits 28 and 51 resonate when the interval d is 15 mm, the transmission output (dashed line) and the reception output when the interval d changes. (Solid line) is shown.

  As is clear from FIG. 3, both the transmission output and the reception output depend on the value of the interval d. When the interval d deviates from the set value (10 mm or 15 mm), both the transmission output and the reception output are greatly reduced. From the graph of FIG. 3, it can be seen that the efficiency of power transmission from the power feeding unit 2 to the power receiving unit 5 decreases as the distance d between the magnetic cores 31 and 54 deviates from the set value.

  FIG. 4 shows the frequency (solid line) of the output signal of the driver 25 of the power supply unit 2 when the transmission output and the reception output show peak values when the distance d between the magnetic cores 31 and 54 is changed, and the power reception unit 5. A measurement example of the received output (broken line) is shown. As is apparent from FIG. 4, as the interval d increases, the frequency of the driving signal for the power feeding unit 2 increases, and conversely, the reception output of the power receiving unit 5 decreases. The reason why the reception output of the power receiving unit 5 decreases as the distance d increases is considered to be because the magnetic flux penetrating the coil 54 of the power receiving unit 5 decreases.

  Consider the measurement results of FIGS. 3 and 4. From FIG. 3, when the interval d between the magnetic cores 31 and 54 deviates from the set value, the transmission output and the reception output are greatly reduced. On the other hand, from FIG. 4, the frequency (solid line) of the output signal of the driver 25 of the power feeding unit 2 when the transmission output and the reception output show peak values increases according to the value of the interval d.

  From these results, when the distance d is changed, the resonance frequency is changed by changing the inductance of the resonance circuit 51 of the power reception unit 5, and the resonance circuit 28 of the power feeding unit 2 can be tuned to the resonance circuit 51 of the power reception unit 5. As a result, the power that can be supplied is expected to be greatly reduced.

  In other words, when the interval d deviates from the set value, the frequency of the driving signal of the power feeding unit 2 is changed in accordance with the resonance frequency of the resonant circuit 51 of the power receiving unit 5, and the resonance circuit 28 and 51 can be tuned to transmit power with optimal efficiency.

  Further, from the result of FIG. 3, it was found that there is a correlation between the transmission output of the power feeding unit 2 and the reception output of the power receiving unit 5, and when the reception output shows a peak value, the transmission output also shows a peak value. .

  The present invention has been made based on the above consideration, and uses a variable frequency oscillation circuit 26 as a means for adjusting the frequency of the output signal of the driver 25 of the power feeding unit 2, and further supplies it to the resonance circuit 28 of the power feeding unit 2. The peak value of the generated power is detected by the value of the current flowing therethrough. The current value of the driving signal supplied to the resonance circuit 28 of the power feeding unit 2 is detected, the frequency of the driving signal is changed based on the detected value, and the current value is set to a value indicating a peak. As shown in FIG. 3, when the transmission output shows a peak value (that is, when the current value supplied to the resonance circuit 28 shows a peak value), the reception output of the resonance circuit 51 of the power receiving unit 5 also shows the peak value. That is, since the resonance circuits 28 and 51 resonate at that frequency, power can be transmitted with optimum efficiency.

<Configuration of contactless power supply device>
Next, with reference to FIG. 1 and FIG. 2, the structure of the non-contact electric power feeder 1 concerning this Embodiment is demonstrated. First, the power feeding unit 2 will be described.

  In FIG. 1, the power variable unit 21 changes the voltage of the AC power supplied from the commercial power supply terminal 37 to a predetermined value using a triac or the like based on the control signal of the control circuit 31.

  The rectifying / smoothing circuit 22 includes a rectifying circuit 23 and a smoothing capacitor 24, and converts AC power supplied from the voltage variable unit 21 into DC power. The voltage of the DC power output from the rectifying / smoothing circuit 22 is adjusted by the output voltage of the voltage variable unit 21.

  The driver 25 is composed of a plurality of FETs and a driving IC (not shown), and modulates the DC power supplied from the rectifying and smoothing circuit 22 with a high-frequency signal from the frequency variable transmission circuit 26 to drive the resonance circuit 28. A rectangular wave signal is generated.

  The variable frequency transmission circuit 26 transmits at a frequency of less than 10 kHz and outputs a high frequency signal having a frequency specified by the control signal of the control circuit 31.

  The rectangular wave signal generated by the driver 25 is supplied to the resonance circuit 28 after the current is limited to a predetermined value by the reactor 27. As described above, the resonance circuit 28 includes the coil 29, the capacitor 30, and the magnetic core 31, and resonates at a frequency specified by the frequency variable transmission circuit 26. The capacitor 30 is connected in parallel with the coil 29. Further, the number of turns of the coil 29 constituting the resonance circuit 28, the capacity of the capacitor 30, and the characteristics of the magnetic core 31 are set to values that resonate at a resonance frequency of less than 10 kHz through experiments.

  A magnetic core 31 shown in FIG. 2 is obtained by processing a magnetic body having a square cross section formed of ferrite or the like into a U shape. In consideration of visibility, only one layer of the coil 29 is wound in FIG. 2, but actually, the coil 29 is wound in multiple layers at the center of the magnetic core 31. Further, the magnetic core 31 is fixed to the casing 38 of the power feeding unit 2 with the end faces of both end portions exposed.

  Returning to the description of FIG. 1, the control circuit 32 controls the operation of the entire power feeding unit 2. Specifically, the control circuit 32 controls the transmission frequency of the frequency variable transmission circuit 26 based on the current value of the rectangular wave signal output from the driver 25 detected using the current transformer 33 and the ammeter 34. . Furthermore, the control circuit 32 confirms that the automatic guided vehicle equipped with the power receiving unit 5 has stopped at the charging standby position based on the signal detected by the light receiver 35, and instructs the power variable unit 21 to supply power.

  The current transformer 33 is used when measuring a large current output from the driver 25. The current transformer 33 is composed of an iron core and a coil, takes out the current corresponding to the number of turns of the coil to the secondary side, and supplies it to the ammeter 34. The current transformer 33 and the ammeter 34 constitute the current detection means of the present invention.

  The AC-DC converter 36 converts AC power supplied from the commercial power supply terminal 37 into DC power of about 5 to 15 volts for driving the IC, and supplies the DC power to the control circuit 32, the frequency variable transmission circuit 26, and the like.

  Next, the power receiving unit 5 will be described. The resonance circuit 51 includes a coil 52, a capacitor 53, and a magnetic core 54, and the capacitor 53 is connected to the coil 52 in series. Further, the number of turns of the coil 52 constituting the resonance circuit 51, the capacity of the capacitor 53, and the characteristics of the magnetic core 54 are set to values that resonate at a resonance frequency of less than 10 kHz through experiments, as in the resonance circuit 28.

  As shown in FIG. 2, the magnetic core 54 has the same shape as the magnetic core 31 of the power feeding unit 2 and is formed of the same material. Similar to the magnetic core 31, a coil 52 is wound in multiple layers at the center of the magnetic core 54. Further, the magnetic core 54 is fixed to the housing 60 of the power receiving unit 5 with the end faces of both ends exposed.

  Returning to the description of FIG. 1, the rectifying and smoothing circuit 55 includes a rectifier 56 and a smoothing capacitor 57, and converts AC power output from the resonance circuit 51 into DC power. The DC power output from the rectifying / smoothing circuit 55 is supplied to the load 58. When the power receiving unit 5 is mounted on an automatic guided vehicle, the load 58 corresponds to a battery charging circuit or a DC / DC converter for supplying driving power to the IC.

  The projector 59 is attached to the front surface of the housing 60 of the power receiving unit 5, and emits light when power is supplied from a battery included in the load 58. When the automatic guided vehicle stops at the charging standby position, the light of the projector 59 enters the light receiver 35 attached to the housing 38 of the power feeding unit 2. The control circuit 31 of the power feeding unit 2 detects that the automatic guided vehicle has stopped at the charging standby position based on the output of the light receiver 35 and starts power feeding.

<Operation of contactless power supply device>
Next, the operation of the non-contact power feeding device 1 will be described. The power supply unit 2 is installed in a power supply stand provided in a factory or the like, and AC power is constantly supplied from the commercial power supply terminal 37 to the power variable unit 21.

  The AC power output from the voltage variable unit 21 is converted into DC power by the rectifying and smoothing circuit 22 and then supplied to the driver 25. The DC power supplied to the driver 25 is modulated by a high frequency signal output from the variable frequency transmission circuit 32 to become a rectangular wave signal, and is supplied to the resonance circuit 28.

The control circuit 32 of the power feeding unit 2 confirms whether or not the automatic guided vehicle is stopped at the charging standby position by the output of the light receiver 35. When the automatic guided vehicle is not stopped at the charging standby position, the control circuit 32 instructs the voltage variable unit 21 to stop the supply of AC power to the rectifying and smoothing circuit 22.
ing

  When the automatic guided vehicle equipped with the power receiving unit 5 stops at the charging standby position, the control circuit 32 of the power feeding unit 2 detects that the automatic guided vehicle stops at the charging standby position by the output signal of the light receiver 35, and Supply of AC power from the variable unit 21 is started.

  The DC power supplied to the driver 25 is converted into a rectangular wave signal by the high frequency signal output from the variable frequency transmission circuit 26. The rectangular wave signal output from the driver 25 is supplied to the resonance circuit 28 as a drive signal after the current is limited by the reactor 27. The resonance circuit 28 resonates at a frequency defined by the variable frequency transmission circuit 26, and power is transmitted to the resonance circuit 51 of the power receiving unit 5 by electromagnetic induction.

  As shown in FIG. 3 described above, when the distance d between the magnetic core 31 on the power feeding unit 2 side and the magnetic core 54 on the power receiving unit 5 side is equal to the set value at the charging standby position of the automatic guided vehicle, transmission is performed. Both the output and the received output show peak values, and power is transmitted with optimum efficiency.

  On the other hand, when the interval d deviates from the set value, both the transmission output and the reception output rapidly decrease, and the power transmission efficiency deteriorates. The control circuit 32 measures the current value of the output signal of the driver 25 using the current transformer 33 and the ammeter 34, and the current value reaches the peak value while shifting the transmission frequency of the frequency variable transmission circuit 26 upward or downward. Adjust to the indicated frequency.

  Since the frequency at which the current value of the resonance circuit 28 exhibits a peak value also indicates the peak value of the current value of the resonance circuit 51 of the power reception unit 5, power is transmitted from the power supply unit 2 to the power reception unit 5 with optimum efficiency.

  As described above, when the non-contact power feeding device of the present invention is used, when the distance d between the magnetic core 31 of the power feeding unit 2 and the magnetic core 54 of the power receiving unit 5 deviates from the set value, the resonance of the power feeding unit 2 is achieved. By changing the frequency of the driving signal of the circuit 28 in accordance with the resonance frequency of the resonance circuit 51 of the power receiving unit 5, the resonance circuits 28 and 51 can be tuned to transmit power with optimum efficiency.

  In the above-described embodiment, as the magnetic cores 31 and 54, those obtained by processing a magnetic material into a U shape are used, but the present invention is not limited to this. A magnetic core processed into an E shape may be used as the magnetic core, and a coil may be wound around the protrusion at the center of the magnetic core.

  The application of the non-contact power feeding device according to the present invention is not limited to the automatic guided vehicle, but can be widely used as a power feeding device for a mobile device that needs to supply power in a non-contact manner such as an electric vehicle or a robot.

DESCRIPTION OF SYMBOLS 1 Non-contact electric power feeder 2 Electric power feeding part 5 Power receiving part 21 Voltage variable part 22, 55 Rectifier smoothing circuit 23, 56 Rectifier 24, 30, 53, 57 Capacitor 25 Driver 26 Frequency variable oscillation circuit 27 Reactor 28, 51 Resonant circuit 29, 52 Coil 31, 54 Magnetic core 32 Control circuit 33 Current transformer 34 Ammeter 35 Light receiver 36 AC-DC converter 58 Load 59 Light receiver

Claims (6)

A non-contact power supply device that supplies power of a power feeding unit to a power receiving unit in a non-contact manner using electromagnetic induction,
The power feeding unit is
A first resonant circuit including a first magnetic core, a first coil wound around the first magnetic core, and a first capacitor;
A first rectifying and smoothing circuit for converting AC power supplied from the outside into DC power;
A driver that generates a high-frequency signal for driving the first resonance circuit based on DC power supplied from the first rectifying and smoothing circuit;
A variable frequency transmission circuit for adjusting the frequency of the high frequency signal generated by the driver;
Current detection means for detecting a current value of a high-frequency signal output from the driver;
A control circuit for controlling the oscillation frequency of the frequency variable oscillation circuit based on the current value detected by the current detection means,
The power receiving unit
A second magnetic core, a second coil wound around the second magnetic core, and a second resonance circuit including a second capacitor;
Contactless power is transmitted from the first coil of the power feeding unit to the second coil of the power receiving unit using resonance between the first resonant circuit and the second resonant circuit. Power supply device. As the first magnetic core and the second magnetic core, a core formed of a U-shaped magnetic body is used,
The non-contact power feeding apparatus according to claim 1, wherein the first magnetic core and the second magnetic core are arranged so that end faces of both ends thereof are opposed to each other. The current detection means includes
A current transformer attached to the wiring on the output side of the driver;
The non-contact electric power feeder according to claim 1 or 2, comprising an ammeter that detects an output current of the current transformer.   The non-contact power feeding device according to claim 1, wherein the power feeding unit further includes a voltage variable unit that adjusts a voltage value of the AC power supplied from the outside.   5. The non-contact power feeding device according to claim 1, wherein the power receiving unit further includes a rectifying and smoothing circuit that converts AC power transmitted to the second resonance circuit into DC power. .   6. The first coil and the first capacitor are connected in parallel, and the second coil and the second capacitor are connected in series. Non-contact power feeding device.

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