JP2016067122A - Non-contact power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission device capable of solving a problem that the resonance state varies due to variation of a load, the resonance voltage of a power transmission resonance system exceeds the withstanding voltage of components constituting the power transmission resonance system and thus the power transmission resonance system is damaged in a non-contact power transmission device based on magnetic field resonance.SOLUTION: In a non-contact power transmission device, a power reception device side monitors required power, and controls the power so that the reception power violently fluctuates according to increase/reduction of reception power and increase/reduction of a load. A power transmission side monitors increase/reduction of a transmission voltage, and supplies proper power according to the load variation. As a result, a capacitor of a resonance circuit can be prevented from being damaged by the load variation. Furthermore, there can be provided a non-contact power transmission device which is adaptable to contamination of foreign materials into a power transmission/reception resonance system, distance variation between the power transmission resonance system and the power reception resonance system, etc., or variation of a load connected to the power reception side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-contact power transmission device that performs non-contact (wireless) power transmission via a power transmission coil provided in a power transmission device and a power reception coil provided in the power reception device.

  As a method of transmitting power in a non-contact manner, an electromagnetic induction type by electromagnetic induction (several hundreds of kHz), an electric field / magnetic field resonance type by transmission between LC resonances via electric field or magnetic field resonance, a microwave power transmission type by radio waves (several GHz), Alternatively, a laser power transmission type using electromagnetic waves (light) in the visible light region is known. Among them, the electromagnetic induction type has already been put into practical use. This has the advantage that it can be realized with a simple circuit (transformer system), but there is also a problem that the transmission distance is short.

  Therefore, recently, electric field / magnetic field resonance type power transmission capable of short-distance transmission (up to 2 m) has attracted attention. Among these, in the case of the electric field resonance type, when a hand or the like is put in the transmission path, the human body is a dielectric, so that energy is absorbed as heat and dielectric loss occurs. On the other hand, in the case of the magnetic resonance type, the human body hardly absorbs energy, and dielectric loss can be avoided. From this point of view, attention to the magnetic resonance type has been increasing.

  Generally, a magnetic resonance type non-contact power transmission device includes a power transmission device and a power reception device. The power transmission device includes a power transmission resonance system including at least a power transmission coil and a resonance capacitor, and a power transmission unit that supplies power to the power transmission resonator. The power receiving apparatus has a power receiving resonance system including at least a power receiving coil and a resonance capacitor. The magnetic resonance type non-contact power transmission device transmits power from the power transmission device to the power reception device in a non-contact manner by utilizing the magnetic resonance between the power transmission resonance system and the power reception resonance system.

  In such a non-contact power transmission device, when the transmission voltage is raised in a state where the load impedance is high (light load), there is a problem that an excessive current is generated in the power transmission device and the power transmission element is destroyed. In order to cope with this problem, it is necessary to use a device that can withstand a higher current value than the actual power transmission state for the power transmission device, which increases the cost of the device.

  In Patent Document 1, in a non-contact power transmission device, an impedance adjustment unit is provided on the power receiving device side to appropriately adjust the input impedance of the power receiving device, thereby preventing an excessive current from being generated in the power transmission device. The structure to perform is disclosed.

JP 2013-146141 A

  In the non-contact power transmission device, when a load change occurs due to the magnitude of power required by the load, the resonance state of the resonance system is changed. This is because the Q value of the resonance system changes due to load fluctuation.

  In general, the Q value of the resonance system becomes high when the load is light due to load fluctuations. Therefore, when the load fluctuation occurs, if the power transmission system is driven with a constant drive voltage and a constant drive waveform, the resonance system The resonance voltage will rise abnormally. Similar to the case where the transmission voltage is raised in a state where the load impedance is high (light load), which was a problem of the prior art, even when a load change occurs, the resonance voltage exceeds the breakdown voltage of the capacitor constituting the resonance circuit. As a result, the capacitor is damaged.

  In the conventional technique shown in Patent Document 1, a complicated configuration for realizing a variable input impedance is essential, and communication may be required between the power transmitting apparatus and the power receiving apparatus. There was a problem that the configuration was complicated.

  An object of the present invention is to provide a technique capable of dealing with the above-described load fluctuation with a relatively simple configuration without performing communication between a power transmission device and a power reception device, and preventing damage to a capacitor constituting a resonance circuit. And

  The non-contact power transmission device of the present invention includes a power transmission device having a power transmission resonance system configured by a power transmission coil and a power transmission capacity, and a power reception device having a power reception resonance system configured by a power reception coil and a power reception capacity, In a non-contact power transmission device that transmits power from a device to the power receiving device in a contactless manner, the power transmission device further includes a drive control circuit that controls an amount of power supplied to a power transmission resonance system, and the power receiving device further includes: An output unit that outputs electric power from the power receiving device; a detection unit that detects AC power received by the power reception resonance system; a cutoff circuit disposed between the detection unit and the output unit; and the cutoff unit Power receiving side control means for controlling the circuit, wherein the power receiving side control means outputs the output from the detection means in the cutoff circuit when an output voltage of the detection means exceeds a predetermined value. When the output voltage of the detection means falls below a predetermined value, the cut-off circuit turns on the power supply from the detection means to the output unit, and the drive control circuit The resonance voltage of the power transmission resonance system is detected, and the amount of power supplied to the power transmission resonance system is adjusted based on the detected resonance voltage.

  In the present invention, the voltage required on the power receiving apparatus side is monitored, and control is performed so that the received voltage does not fluctuate in accordance with increase or decrease in received power and increase or decrease in load. In addition, the power transmission apparatus side monitors the increase and decrease of the transmission voltage, and supplies appropriate power for load fluctuations.

  As a result, damage to the capacitor of the resonance circuit due to load fluctuation can be prevented. In addition, it is possible to provide a non-contact power transmission device that can cope with foreign matter mixed into the power transmission / reception resonance system, a change in the distance between the power transmission resonance system and the power reception resonance system, or a change in the load connected to the power reception side. .

The block diagram which shows the structure of the non-contact electric power transmission apparatus in Embodiment 1 of this invention. First circuit diagram of cut-off circuit and power receiving side control means in Embodiment 1 of the present invention Second circuit diagram of cut-off circuit and power reception side control means in embodiment 1 of the present invention Third circuit diagram of cut-off circuit and power receiving side control means in embodiment 1 of the present invention The block diagram which shows the structure of the non-contact electric power transmission apparatus in Embodiment 2 of this invention.

<Embodiment 1>
FIG. 1 shows a schematic configuration of a non-contact power transmission apparatus 100 according to Embodiment 1 of the present invention. The non-contact power transmission device 100 includes a power transmission device 10 and a power reception device 20. The power transmission device 10 includes a power transmission resonance system 50 for non-contact transmission of high-frequency power. The power reception device 20 includes a power reception resonance system 60 for receiving high-frequency power transmitted by the power transmission resonance system 50 of the power transmission device 10. The contactless power transmission device 100 of the present invention magnetically couples the power transmission resonance system 50 and the power reception resonance system 60 to transmit power from the power transmission device 10 to the power reception device 20 in a contactless manner.

  The power transmission device 10 further includes a drive circuit 30 that drives the power transmission resonance system 50 and a drive control circuit 40 that detects the resonance voltage of the power transmission resonance system 50 and controls the drive power of the drive circuit 30.

  The power receiving device 20 further includes a detecting unit 71 for detecting the output of the power receiving resonance system 60, a cut-off circuit 72 for turning on / off whether or not the output power of the detecting unit 71 is output from the power receiving device 20, and insufficient received power. In this case, the power supply means 73 includes a power supplement means 73 for supplementing power, an adder 74 for adding power, a power receiving side control means 80 for controlling the cutoff circuit 72, and an output section 90 for outputting power.

  A load (not shown) is connected to the output unit 90. When the load is light and the output power from the output unit 90 is not necessary, the power consumption of the power receiving device is smaller than the power supplied from the power transmitting device, and the power receiving voltage increases. In that case, the power receiving side control means 80 cuts off the output power of the detection means 71 by the cut-off circuit 72 to avoid the increase of the voltage on the load 90 side. On the other hand, when the load is heavy and the output power from the output unit 90 is insufficient, the power receiving side control unit 80 performs control to replenish power by the power replenishing unit 73.

  As in the prior art disclosed in the publicly known document, the power transmission device 10 and the power reception device 20 are separately provided with a communication unit, and the power reception device 20 transmits information indicating that the load connected to the power reception device 20 is reduced to the power transmission device 10. The power transmission device 10 that has received the information can cope with load fluctuations even if it is controlled to reduce the power of the drive circuit.

On the other hand, in the non-contact power transmission apparatus of the present invention, first, the behavior of the power receiving resonance system is controlled with respect to the load fluctuation. Thereby, the change by load fluctuation is absorbed in the power receiving apparatus side. At the same time, the power transmission device adjusts the transmission power independently of the power receiving side. That is, in the non-contact power transmission device, it is not necessary to separately provide communication means in the power transmission device 10 and the power reception device 20 in order to cope with load fluctuations. Hereinafter, a means for controlling the power receiving resonance system with respect to load fluctuation will be described.
(Power control based on voltage monitoring of the power receiving resonance system)
The power transmission / reception resonance system including the power transmission resonance system 50 and the power reception resonance system 60 in FIG. 1 has a coupling coefficient variation or a load variation depending on the relative positional relationship between the power transmission resonance system 50 and the power reception resonance system 60. Then, the resonance voltage and resonance frequency of the power transmission resonance system 50 and the power reception resonance system 60 change.

  In FIG. 1, for example, when the power consumption of an electrical device or the like is reduced, the load is reduced. When the load connected to the output unit 90 becomes lighter, the load of the power receiving resonance system 60 decreases, so the resonance voltage of the power receiving resonance system rises and the output voltage of the detection means 71 tends to rise.

  The power receiving side control unit 80 monitors the voltage of the output unit 90. When detecting that the voltage of the output unit 90 exceeds a predetermined value, the power receiving side control unit 80 turns off the cutoff circuit 72 and cuts off the supply of power from the detection unit 71 to the output unit 90. Thereby, the voltage rise of the output part 90 caused by the electric power output from the detection means 71 can be suppressed.

  When the power receiving side control means 80 detects that the voltage of the output section 90 again becomes a predetermined value or less, the power receiving side control means 80 turns on the cutoff circuit 72 and supplies the output of the detection means 71 to the output section 90.

  However, if the output of the detection means 71 is cut, the power output from the power transmission / reception resonance system to the outside decreases, and the power is accumulated in the power transmission / reception resonance system. That is, the resonance voltage of the power transmission resonance system 50 also increases.

  Therefore, the drive control circuit 40 detects the resonance voltage of the power transmission resonance system 50 and reduces the output power from the drive circuit 30. As a result, it is possible to suppress an increase in the resonance voltage of the power transmission resonance system 50 and the power reception resonance system 60, to cope with a decrease in the load of the output unit 90, and to prevent damage to the capacitors of the power transmission resonance system 50 and the power reception resonance system 60. it can.

  2A to 2C are circuit diagrams of the cut-off circuit 72 and the power receiving side control means 80. FIG. The power receiving device 20 includes components other than the cut-off circuit 72 and the power receiving side control means 80. However, in FIG. 2A to FIG. 2C, components other than the cutoff circuit 72 and the power receiving side control unit 80 in the power receiving device 20 are omitted in order to simplify the description of the cutoff circuit 72 and the power receiving side control unit 80.

  FIG. 2A shows a first circuit diagram of the cutoff circuit 72 and the power receiving side control means 80. In the first circuit of FIG. 2A, since the power receiving side control means 80 is configured by the comparator 801, DC power is separately supplied to the comparator 801. The power to the comparator 801 may be supplied by converting the output power of the detection means 71 into a predetermined voltage, or a separate power source may be prepared. As shown in FIG. 1, power is input from the detection means 71 to the cutoff circuit 72.

  In FIG. 2A, when the load becomes lighter and the voltage at point A rises and the point B divided by resistance exceeds the reference voltage of the comparator 801, the output of the comparator 801 changes from High to Low. As a result, the transistor 721 is turned off and the FET 723 is also turned off.

  Thereafter, when the voltage at the point A decreases and the voltage at the point B falls below the reference voltage of the comparator 801 having hysteresis, the output of the comparator 801 changes from Low to High, and the FET 723 is turned on. The supply of power is resumed.

  FIG. 2B shows a second circuit diagram of the cutoff circuit 72 and the power receiving side control means 80. The second circuit of FIG. 2B is simplified compared to the first circuit of FIG. 2A.

  In FIG. 2B, when the voltage at the point B increases, the transistor 802 is turned on and the transistor 722 is also turned on, so that the FET 723 is turned off. However, in this case, although depending on the switching speed of the transistor 802, in general, the response is considerably slower than in the case of FIG. 2A, and the FET 723 generates considerable heat when the transistor 802 is turned on.

  FIG. 2C shows a third circuit diagram of the cutoff circuit 72 and the power receiving side control means 80. By configuring the power receiving side control means 80 with a current switch, the response speed, which is the problem of FIG. 2B, can be improved.

  Next, the case where the load connected to the output unit 90 shown in FIG. 1 becomes heavy will be described. For example, when the power consumption of an electrical device or the like connected to the output unit 90 increases, the load becomes heavy. When the load connected to the output unit 90 becomes heavy, the voltage of the output unit 90 decreases from the reference.

  Therefore, when the power receiving side control unit 80 detects that the voltage of the output unit 90 has decreased below the reference, the power receiving side control unit 80 supplies power through the adder 74 by means of the power supplementing unit 73. Thereby, the fall of an output voltage can be prevented and stable electric power supply is attained.

  The decrease in the output voltage of the output unit 90 when the load becomes heavy always occurs due to the power supply behavior of the power transmission / reception system. First, when the load increases, the power output from the power receiving resonance system 60 through the detection means 71 increases. The increasing electric power is covered by receiving energy from the resonating magnetic field generated by the power transmission resonance system 50 and supplying it to the load.

  That is, the power output from the drive circuit 30 is output from the detection means 71 in accordance with the impedance of the power transmission / reception system including the load. Here, the power transmission resonance system 50 and the power reception resonance system 60 constitute a power transmission / reception resonance system. The power is transmitted from the power transmission device 10 to the power reception device 20 via a filter having a time constant called the power transmission / reception resonance system. Is transmitted. Therefore, when the power required for the load changes, a predetermined time is required to follow the change. The power supplement means 73 of the present invention compensates for this temporary voltage drop.

The power replenishing means 73 constituted by a capacitor or the like is charged when the load is light, and is adjusted by discharging when the load is heavy.
<Embodiment 2>
FIG. 3 shows a schematic configuration of the non-contact power transmission apparatus 101 according to the second embodiment of the present invention. Compared with Embodiment 1 shown in FIG. 1, the power receiving device 21 is different. Hereinafter, the power receiving device 21 will be described in detail.

  The power received by the power receiving resonance system 60 is converted into DC power by the both-wave rectifier 711 and then fed to a load (not shown) connected to the output unit 90. When the undervoltage detector 812 determines that the load of the output unit 90 becomes heavy and the transmission power alone is insufficient, the switch 734 is turned on to supply the power stored in the power storage unit 732 to the output unit 90.

  On the other hand, when the power output from the output unit 90 decreases, that is, when the power supply from the output unit 90 becomes excessive, the surplus power is stored in the power storage unit 732 via the diode 731.

  However, when the power supply from the output unit 90 becomes excessive and the power storage unit 732 is fully charged, the voltage of the output unit 90 tends to increase. At this time, the excess voltage detector 811 detects a rise in the voltage of the output unit 90 and opens the switch 712. As a result, the electric power output from the both-wave rectifier 711 is not supplied to the output unit 90, and an abnormal voltage increase of the output unit 90 can be prevented.

  When the switch 712 is opened and the output from the both-wave rectifier 711 is not consumed, power is accumulated in the power transmission / reception resonance system. That is, the resonance voltage of the power transmission resonance system 50 also increases.

  Therefore, the drive control circuit 40 detects the resonance voltage of the power transmission resonance system 50, and reduces the output power from the drive circuit 30 when the resonance voltage exceeds a predetermined value. As a result, an increase in the resonance voltage of the power transmission resonance system 50 and the power reception resonance system 60 can be suppressed, and it is possible to cope with a decrease in the load of the output unit 90 and to prevent damage to the capacitor.

  The non-contact power transmission device of the present invention can prevent the power transmission circuit from being damaged while adjusting the amount of power to be transmitted according to the load variation.

DESCRIPTION OF SYMBOLS 10 Power transmission apparatus 20, 21 Power reception apparatus 30 Drive circuit 40 Drive control circuit 50 Power transmission resonance system 60 Power reception resonance system 71 Detection means 711 Both-wave rectifier 712 Switch 72 Cut-off circuit 721, 722 Transistor 723 FET
73 Power supplement means 731 Diode 732 Power storage means 734 Switch 74 Adder 80 Power receiving side control means 801 Comparator 802 Transistor 811 Overvoltage detector 812 Undervoltage detector 90 Output unit 100, 101 Non-contact power transmission device

Claims (2)

A power transmission device having a power transmission resonance system composed of a power transmission coil and a power transmission capacity;
A power receiving device having a power receiving resonance system constituted by a power receiving coil and a power receiving capacity;
In a non-contact power transmission device that transmits power in a non-contact manner from the power transmission device to the power reception device,
The power transmission device further includes a drive control circuit that controls the amount of power supplied to the power transmission resonance system,
The power receiving device further includes:
An output unit for outputting power from the power receiving device;
Detection means for detecting AC power received by the power receiving resonance system;
A cutoff circuit disposed between the detection means and the output unit;
Power receiving side control means for controlling the cut-off circuit,
The power receiving side control means turns off the supply of power from the detection means to the output unit in the cut-off circuit when the output voltage of the detection means exceeds a predetermined value, and the output voltage of the detection means Turn on the power supply from the detection means to the output unit in the cut-off circuit when below a predetermined value,
The drive control circuit detects a resonance voltage of the power transmission resonance system, and adjusts an amount of power supplied to the power transmission resonance system based on the detected resonance voltage. The power receiving device includes power supplement means,
The power replenishing means replenishes the output power of the cut-off circuit when a temporary decrease in the output power of the cut-off circuit occurs due to on / off by the cut-off circuit. Item 2. The non-contact power transmission device according to Item 1.

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