JP2016052241A - Non-contact power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission device without need of adding a constant voltage control circuit, compatible with a wide input voltage, to the power reception side.SOLUTION: Fifth to eighth switch elements 20-23 are connected in parallel with each of first to fourth diodes 12-15 constituting a rectifier circuit on the power reception side of the non-contact power transmission device. In synchronization with a signal to alternately switch on and off a set of first to fourth switch elements 3, 6 on the power transmission side and a set of second and third switch elements 4, 5, a set of the fifth and the sixth switch elements 20, 21 and a set of the seventh and the eighth switch elements 22, 23 are alternately switched on and off.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a switching power supply, and more particularly to a contactless power transmission device.

As a conventional non-contact power transmission apparatus, there is a method provided by Patent Publication 2002-354711. An example of a circuit diagram shown as the embodiment is shown in FIG.
In FIG. 6, the high frequency generator 101 supplies a high frequency current to the power transmission coil 102, the power reception coil 103 electromagnetically coupled to the power transmission coil 102 receives power, the rectifier 104 converts it into direct current, a reactor 105 and a switch A step-up chopper composed of the element 106, the diode 107, and the capacitor 108 has a constant voltage.
Since the non-contact power transmission device is separated from the power transmission side and the power reception side, the voltage of the capacitor 108 cannot be fed back to the power transmission side and controlled.
In the circuit shown in FIG. 6, a constant voltage control circuit using a step-up chopper is inserted between the rectifier 104 and the capacitor 108, but the output voltage of the rectifier 104 is also in the resonance condition of the circuit when the load is unloaded. However, since the voltage rises to a high voltage, the constant voltage control circuit must stabilize the output voltage with respect to a wide input voltage.

  The present invention provides a contactless power transmission device that does not need to add a constant voltage control circuit corresponding to a wide input voltage to the power receiving side by providing a function of stabilizing the DC voltage to the power receiving side rectifier circuit. It is an object.

  The invention described in claim 1 is a DC circuit, a first capacitor, a series circuit composed of first and second switch elements connected in parallel to the DC power supply, and a third circuit connected in parallel to the DC power supply. An oscillation control circuit for alternately turning on / off a set of the first switch element and the fourth switch element and a set of the second switch element and the third switch element; A series circuit of a power transmission coil and a power transmission capacitor connected between the connection point of the first switch element and the second switch element, the connection point of the third switch element and the fourth switch element, the power transmission coil and the electromagnetic A first circuit connected between one terminal of the series circuit of the power receiving coil and the power receiving capacitor and one terminal of the first capacitor; Receiving A second diode connected between the other terminal of the series circuit of the coil and the receiving capacitor and the other terminal of the first capacitor; a connection point between the series circuit consisting of the receiving coil and the receiving capacitor and the first diode; A third diode connected between a connection point of the second diode and the first capacitor; a series circuit including a receiving coil and a receiving capacitor; a connection point of the second diode; a first diode; In a non-contact power transmission device including a fourth diode connected between connection points of capacitors, a fifth switch element is connected in parallel to the first diode, and a sixth switch is connected in parallel to the second diode. And a seventh switch element connected in parallel to the third diode, an eighth switch element connected in parallel to the fourth diode, and the first switch element. The fifth switch element and the sixth switch element are turned on / off in synchronization with the on / off of the fourth switch element set, and the second switch element and the third switch element set are turned on / off. A synchronous drive circuit that turns on and off the set of the seventh switch element and the eighth switch element in synchronization with the off state is added.

  In the invention described in claim 2, the third switch element described in claim 1 is replaced with a second capacitor, and the fourth switch element is replaced with a third capacitor.

  According to a third aspect of the present invention, the parallel circuit comprising the fourth diode and the eighth switch element according to the first or second aspect is replaced with a fourth capacitor, and the second diode and the sixth switch element are formed. The parallel circuit was replaced with a fifth capacitor.

  According to a fourth aspect of the present invention, a PWM circuit for controlling the width of a pulse generated by the synchronous drive circuit according to the first to third aspects is added.

  In the invention described in claim 5, the series circuit including the power receiving coil and the power receiving capacitor described in claims 1 to 4 is replaced with a parallel circuit including the power receiving coil and the power receiving capacitor.

Effect of the invention

  Since the non-contact power transmission device of the present invention does not require a constant voltage control circuit on the power receiving side, the efficiency is improved, the space inside the device on the power receiving side is vacant, and the cost is reduced.

  The best mode for carrying out the invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.
In the figure, 1 is a DC power source, 2 is a first capacitor, 3 to 6 are first to fourth MOSFETs, 7 is an oscillation control circuit, 8 is a power transmission coil, 9 is a power transmission capacitor, 10 is a power reception coil, 11 is Power receiving capacitors, 12 to 15 are first to fourth diodes, 20 to 23 are fifth to eighth MOSFETs, and 24 is a synchronous drive circuit. Reference numerals 51 to 58 denote insulating buffers for applying signals from the same signal source to gates having different potentials.

  The oscillation control circuit 7 in FIG. 1 alternately turns on / off the set of the first MOSFET 3 and the fourth MOSFET 6 and the set of the second MOSFET 4 and the third MOSFET 5. In order to prevent the two sets from being turned on at the same time, a period during which both sets are turned off is provided. This period is called dead time.

  Since the oscillation period of the oscillation control circuit 7 is selected to be close to the resonance period determined by the electromagnetic coupling between the power transmission side and the power reception side, the current becomes a sine wave.

  The synchronous drive circuit 24 generates a pulse having a predetermined pulse width in response to the switching timing of the polarity of the voltage across the series circuit of the power receiving coil 10 and the power receiving capacitor 11.

  Since the degree of coupling between the power transmission coil and the power reception coil is low, in the case of FIG. 1, the first diode 12 and the second diode 13 on the power reception side when the pair of the second MOSFET 4 and the third MOSFET 5 are turned off from the on state. It becomes the polarity which the group of becomes conductive. Therefore, the voltage at both ends of the series circuit including the power receiving coil 10 and the power receiving capacitor 11 is delayed by the dead time from the timing when the voltage is switched to the polarity in which the first diode 12 and the second diode 13 are conducted, and the fifth MOSFET 20 and the When a pulse for turning on the six MOSFETs 21 is generated, the oscillation control circuit 7 on the power transmission side synchronizes with the pulse for turning on the set of the first MOSFET 3 and the fourth MOSFET 6.

  FIG. 5 shows waveforms of a pulse generated by the oscillation control circuit 7, a voltage generated across the series circuit including the power receiving coil 10 and the power receiving capacitor 11, and a pulse generated by the synchronous drive circuit 24. In the figure, Ton1 and Td1 are the pulse width and dead time produced by the oscillation control circuit 7, and Ton2 and Td2 are the pulse width and dead time produced by the synchronous drive circuit 24. The value of Td2 is the same as the value of Td1.

  Since the synchronous drive circuit 24 is turned off before the on-period of the oscillation control circuit on the power transmission side ends, the value of Ton2 becomes smaller than the value of Ton1.

When the current flowing from the first capacitor 2 to the load becomes lighter, in the conventional method, the voltage of the first capacitor rises due to the current having a narrow width flowing through the first to fourth diodes and a high peak value. If the rectifier circuit is composed only of diodes, once the voltage has risen, it is difficult for the light load to drop.
On the other hand, in the present invention, a switch element is connected in parallel to the diode and the switch element is forcibly turned on, so that energy regeneration is performed from the first capacitor 2 to the power transmission side, thereby suppressing an increase in voltage.

  By appropriately selecting the ON period of the synchronous drive circuit, the voltage of the first capacitor 2 can be kept below a predetermined value even when there is no load. If a load is connected to the first capacitor 2, a stable voltage can be supplied to the load.

  FIG. 2 is a circuit diagram showing an embodiment of the second aspect of the present invention. Components common to those in FIG. 1 are the same as those in FIG. In the figure, the second capacitor 25 and the third capacitor 26 divide the voltage of the DC power source 1 into two equal parts. Since both capacitors are selected to have a value larger than the capacity of the power transmission capacitor 9, there is no effect on the resonance period of the circuit.

  FIG. 3 is a circuit diagram showing an embodiment of the third aspect of the present invention. Components common to those in FIG. 1 are the same as those in FIG. In the figure, the fourth capacitor 27 is charged when the first diode 12 becomes conductive. The fifth capacitor 28 is charged when the third diode 15 becomes conductive. The first capacitor 2 is charged with the combined voltage of the fourth and fifth capacitors.

  2 to 3, the operations of the oscillation control circuit 7 and the synchronous drive circuit 24 are the same as those in FIG.

FIG. 4 is a circuit diagram showing an embodiment of the third aspect of the present invention. Components common to those in FIG. 1 are the same as those in FIG.
In the figure, the PWM circuit 29 monitors the voltage across the first capacitor 2, and if it is higher than the reference voltage, the pulse width generated by the synchronous drive circuit 24 is lengthened, and the ON period of each of the fifth to eighth switch elements is increased. Lengthen. If the ON period of each of the fifth to eighth switch elements becomes longer, the power returning from the power reception side to the power transmission side increases, and the voltage of the first capacitor 2 decreases. This increases the stability of the voltage of the first capacitor 2.

  FIG. 5 is a circuit diagram showing an embodiment of the invention as set forth in claim 5. Components common to those in FIG. 1 are the same as those in FIG.

  In FIGS. 1 to 5, since MOSFETs are selected as the fifth to eighth switch elements, the first to fourth diodes can be omitted by substituting the parasitic diodes of the MOSFETs.

Industrial applicability

  It is possible to provide a new means for stabilizing the voltage applied to the load, which is one of the problems of the conventional non-contact power transmission apparatus. Thereby, a non-contact electric power transmission apparatus becomes easy to spread.

It is a circuit diagram which shows one Example of this invention. It is a circuit diagram which shows one Example of this invention. It is a circuit diagram which shows one Example of this invention. It is a circuit diagram which shows one Example of this invention. It is a circuit diagram which shows one Example of this invention. It is a wave form diagram of the circuit diagram of FIG. It is a circuit diagram which shows an example of a conventional system.

Brief description of symbols

1 DC power supply 2 Capacitor 3-6 MOSFET
7 Oscillation Control Circuit 8 Power Transmission Coil 9 Capacitor 10 Power Receiving Coil 11 Capacitor 12-15 Diode 20-23 MOSFET
24 Synchronous Drive Circuit 25-28 Capacitor 29 PWM Circuit 51-58 Insulation Buffer 101 High Frequency Power Supply 102, 103 Coil 104 Bridge Rectifier 105 Reactor 106 Switch Element 107 Diode 108 Capacitor 109 Load 112, 113 Capacitor

Claims (5)

  A series circuit composed of a DC power source, a first capacitor, and a first and second switch elements connected in parallel to the DC power source, and a series composed of third and fourth switch elements connected in parallel to the DC power source. Connection point of oscillation control circuit for alternately turning on / off a circuit, a set of the first and fourth switch elements, and a set of the second and third elements, and the first and second switch elements And a series circuit composed of a power transmission coil and a power transmission capacitor connected between connection points of the third and fourth switch elements, and a series circuit composed of a power reception coil and a power reception capacitor electromagnetically coupled to the power transmission coil And a first diode connected between one terminal of a series circuit composed of the power receiving coil and the power receiving capacitor and one terminal of the first capacitor, a direct current composed of the power receiving coil and the power receiving capacitor. A second diode connected between the other terminal of the circuit and the other terminal of the first capacitor, a series circuit composed of the receiving coil and the receiving capacitor, a connection point of the first diode, and the second diode A third circuit connected between a connection point of the diode and the first capacitor, a series circuit including the power receiving coil and the power receiving capacitor, a connection point of the second diode, the first diode, and the first diode In the non-contact power transmission device including the fourth diode connected between the connection points of the capacitors, a fifth switch element is connected in parallel to the first diode, and a second diode is connected in parallel to the second diode. 6 switch elements, a seventh switch element is connected in parallel with the third diode, and an eighth switch element is connected in parallel with the fourth diode. The fifth and sixth switch elements are turned on / off in synchronization with the on / off of the first and fourth switch elements, and the second and third switch elements are set. A non-contact power transmission apparatus, wherein a synchronous drive circuit for turning on / off the set of the seventh and eighth switch elements in synchronization with on / off is added.   The non-contact power transmission apparatus according to claim 1, wherein the third switch element is replaced with a second capacitor, and the fourth switch element is replaced with a third capacitor.   The parallel circuit composed of the fourth diode and the eighth switch element is replaced with a fourth capacitor, and the parallel circuit composed of the second diode and the sixth switch element is replaced with a fifth capacitor. The non-contact power transmission device according to claim 1 or 2.   4. The non-contact power transmission apparatus according to claim 1, further comprising a PWM circuit that controls a width of a pulse generated by the synchronous drive circuit in order to stabilize the voltage of the first capacitor.   The non-contact power transmission device according to any one of claims 1 to 4, wherein a series circuit including the power receiving coil and a power receiving capacitor is replaced with a parallel circuit including the power receiving coil and the power receiving capacitor.

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