JP2017011980A - Non-contact power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for generating from a high frequency current a stable AC current or a DC current by controlling an AC phase, instead of generating a stable DC voltage from a DC voltage which is obtained through rectification and smoothing on the power reception side.SOLUTION: The power transmission side of a non-contact power transmission device directly switches an AC current to generate a high frequency current. The power reception side generates a pulse by the comparison of an AC envelope extracted from the high frequency current with a threshold, so that the pulse switches on and off a bidirectional switch through a logic circuit to stabilize a voltage or a current applied to a load.SELECTED DRAWING: Figure 1

Description

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

  Japanese Patent No. 4835985 registered by the present applicant as a method for directly turning on and off an alternating current in a conventional non-contact power transmission apparatus. One such embodiment is shown in FIG.

In FIG. 8, 111 is an AC power source, and 112 to 120 are inverters that generate high-frequency current by turning on and off the AC current. The high-frequency current is transmitted by the power transmission coil 121 and the power reception coil 122 and converted into direct current by the rectifier 123. Since the DC voltage is unstable, it is stabilized by the constant voltage circuit 124 and supplied to the load 125.
The conventional method shown in FIG. 8 stabilizes the voltage applied to the load by adding a constant voltage circuit on the power receiving side. However, since the voltage applied to the constant voltage circuit increases at light loads, the input voltage of the constant voltage circuit is reduced. It must be widened, which increases costs and decreases efficiency.

  It is an object of the present invention to provide a technique for generating a stable alternating current or a direct current from a high frequency current by controlling the phase of the alternating current instead of creating a stable direct current voltage from the rectified and smoothed direct current voltage on the power receiving side. Yes.

  The invention according to claim 1 is an AC power source, an inverter that converts AC current into high-frequency current, a first antenna that emits high-frequency current into the air as electromagnetic energy, and a second antenna that receives the electromagnetic energy. And a non-contact power transmission device comprising a load for supplying a high-frequency current generated in the second antenna, a first bidirectional switch is inserted in series on one line connecting the second antenna and the load, A second bidirectional switch is inserted in series with the other line connecting the antenna and the load between the second antenna side terminal of the first bidirectional switch and the load side terminal of the second bidirectional switch. A third bidirectional switch is connected, a fourth bidirectional switch is connected between the load side terminal of the first bidirectional switch and the second antenna terminal side of the second bidirectional switch; Alternating high-frequency current generated in the antenna A rectifying circuit for extracting the tangential line, generating a pulse only during a period when the output voltage of the rectifying circuit exceeds the threshold value, and making each of the first to fourth bidirectional switches conductive in the positive direction; and In order to stabilize the AC voltage applied to the load, and a logic circuit that repeatedly supplies the AC current to the load by repeatedly conducting the first to fourth bidirectional switches in the negative direction with a pulse generated next to the pulse. A control circuit for controlling the threshold is added.

  According to the second aspect of the present invention, the logic circuit repeatedly conducts the first to fourth bidirectional switches only in the positive direction of each pulse to supply a DC current to the load, and the control circuit generates a DC voltage applied to the load. Control the threshold to stabilize.

  In the invention according to claim 3, the second bidirectional switch and the fourth bidirectional switch are replaced with capacitors.

  According to a fourth aspect of the present invention, in the second aspect, the second bidirectional switch and the fourth bidirectional switch are both replaced with diodes.

  According to a fifth aspect of the present invention, in the second to fourth aspects of the invention, the bidirectional switch is replaced with a unidirectional switch in which one MOSFET and one diode are connected in series.

  According to a sixth aspect of the invention, in the first to fifth aspects of the invention, the control circuit controls the threshold value in order to stabilize the current applied to the load.

  The contactless power transmission device of the present invention is stable in the load without increasing power loss by replacing the rectifying diode and the constant voltage circuit provided on the power receiving side of the conventional device with a bidirectional switch or a unidirectional switch. The reduced voltage or current can be supplied, so that the cost can be reduced.

  If the power receiving side is applied to a vehicle, weight reduction becomes an important issue, but it can contribute to weight reduction by reducing circuit parts and reducing power loss.

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

FIG. 1 is a circuit diagram showing an embodiment relating to the first aspect of the present invention.
FIG. 2 is a diagram showing waveforms at various parts on the circuit diagram shown in FIG.
In FIG. 1, 1 is an AC power source, 2 is an inverter, 3 is a capacitor, 4 is a first antenna, 5 is a second antenna, 6 is a capacitor, and 7 is a load. Reference numerals 11 and 12 denote MOSFETs, and a pair of two constitutes a first bidirectional switch. Reference numerals 21 and 22, 31 and 32, and 41 and 42 are MOSFETs, and each pair constitutes a second to a fourth bidirectional switch. Reference numerals 13 and 14, 23 and 24, 33 and 34, and 43 and 44 are insulating drivers for driving the MOSFET.

  In FIG. 1, reference numerals 51 to 55 denote rectifying and smoothing circuits. The voltage of the waveform shown in FIG. 2 (1) is applied to the input of 51 diodes, and the insulation amplifier of 55 is shown in FIG. 2 (2). Waveform voltage is output. 101 shown in (2) of FIG. 2 indicates a threshold value, which is given by a control circuit 57 described below.

  In FIG. 1, the voltage applied to the load 7 is divided by resistors 58 and 59 and applied to the feedback control terminal of the control circuit 57, and the output voltage of the insulation amplifier 55 is applied to the feedforward control terminal of the control circuit 57. The control circuit 57 outputs a signal having the waveform shown in FIG. 56 is a logic circuit, and the signal of (3) in FIG. 2 inputted to its terminal A is converted into every other signal shown in (4) and (5), and terminals B and C of the logic circuit 56 are respectively converted. Is output from. The terminal G of the logic circuit 56 is a ground terminal for the terminals B and C.

  Further, U and V on the circuit of FIG. 1 are points on the circuit provided for explanation, U is a connection point between the first bidirectional switch and the third bidirectional switch, and V is a fourth point. At the connection point of the bidirectional switch and the second bidirectional switch.

  The pulse width of the signal output from the control circuit 57 is changed by changing the value of the threshold value 101 shown in (2) of FIG. When the pulse width changes, the phase at which the bidirectional switch is turned on and off changes, and the output voltage changes.

  That is, when the voltage applied to the load becomes higher than the reference value, the threshold value is increased, the signal pulse of the control circuit 57 is shortened, and the ON width of the bidirectional switch is shortened, so the voltage applied to the load is lowered.

  When examining the state at time T1 in FIG. 2, a high-frequency voltage swinging positive and negative is applied between U and V in FIG. Since the signal (4) in FIG. 2 is output to B of the logic circuit 56 and no signal is output to C, the MOSFETs 11, 21, 31, and 41 are turned on, and the MOSFETs 12, 22 are output. , 32 and 42 are in an off state. In this state, when the high-frequency voltage is positive, the current flows in the order of the MOSFET 11, the body diode of the MOSFET 12, the load 7, the MOSFET 21, and the body diode of the MOSFET 22. When the high-frequency voltage is negative in the same state, the current flows in the order of the MOSFET 41, the body diode of the MOSFET 42, the load 7, the MOSFET 31, and the body diode of the MOSFET 32. That is, a current flowing from the top to the bottom of the figure flows through the load 7 regardless of whether the high frequency voltage is positive or negative.

  In FIG. 2, when the state at time T2 is examined, a signal is output to C of the logic circuit 56 and no signal is output to B. Therefore, following the current in the same manner as described above is related to the sign of the high-frequency voltage. Instead, a current flows from the bottom to the top of the load 7. That is, alternating current synchronized with the input alternating voltage flows through the load.

  In FIG. 1, since the bidirectional switch is configured by connecting two MOSFETs in series in reverse, the body diode of the MOSFET is used. When a switch element having no body diode, such as an IGBT, is used in the embodiment of FIG. 1, it is possible to connect a diode to each 1 GBT in parallel as shown in FIG.

FIG. 3 is a circuit diagram showing an embodiment according to the second aspect of the present invention.
In the figure, the signal having the waveform (3) in FIG. 2 is output from the terminal D of the logic circuit 56, and the MOSFETs 11, 21, 31, and 41 are repeatedly turned on and off. Since the signals for driving the gates of the MOSFETs 12, 22, 32, and 42 are off, only the body diode works, and a DC current in one direction flows through the load 7.

FIG. 4 is a circuit diagram showing an embodiment according to the third aspect of the present invention.
In the figure, 25 and 45 are capacitors. The same signals as in the case of FIG. 1 are output from the terminals B and C of the logic circuit 56. 2 at time T1 in FIG. 2 is that the MOSFETs 11 and 31 are in the on state, the high-frequency voltage between U and V is positive when the current swings in the order of the MOSFET 11, the body diode of the MOSFET 12, and the capacitor 45. It flows and charges the capacitor 45. When it swings negatively, the current flows in the order of the capacitor 25, the MOSFET 31, and the body diode of the MOSFET to charge the capacitor 25. A voltage obtained by adding the voltages of the two capacitors is applied to the load 7 with the top of the figure being positive.

  In the state at time T2 in FIG. 2 in FIG. 4, since the MOSFETs 12 and 32 are on, the high frequency voltage between U and V is charged in the capacitors 45 and 25 in the reverse direction, and the load 7 has two capacitors. The added voltage is added with the bottom of the figure plus.

FIG. 5 is a circuit diagram showing an embodiment according to the fourth aspect of the present invention.
In the figure, reference numerals 26 and 46 denote diodes. The same signal as in FIG. 3 is output from the terminal D of the logic circuit 56, and the MOSFETs 11 and 31 are repeatedly turned on and off.

FIG. 6 is a circuit diagram showing an embodiment of the invention as set forth in claim 5.
In the figure, reference numerals 15 and 35 denote diodes.

FIG. 7 is a circuit diagram showing an embodiment according to the sixth aspect of the present invention.
In the figure, reference numeral 61 denotes a resistor for detecting a current, and the threshold value is controlled so that the voltage across the resistor is stabilized.

  In each of the circuits of FIGS. 1 and 3 to 5, the bidirectional switch is configured by arranging two N-channel MOSFETs with the common source and facing each other, but with the anode common and facing each other. You may do it. In FIG. 6, the anode of the diode is connected to the source of the MOSFET to form a series connection, but the diode cathode and the drain of the MOSFET may be connected to form a series connection.

  In each circuit of FIGS. 1 and 3 to 5, the bidirectional switch is configured by a MOSFET, but may be configured by using an IGBT and a diode as illustrated in FIG. 7A. Further, as shown in FIG. 7B, a Schottky barrier diode having a forward drop voltage smaller than that of the body diode may be connected in parallel to the MOSFET.

  In each of the circuits shown in FIGS. 1 to 7, the aerial wire is represented by a coil, and the wire length of the coil is determined according to the wavelength of the high-frequency current so that electric power is transmitted most efficiently. When the actual line length is less than the obtained value, the equivalent line length of the antenna may be extended by inserting an inductor in series as shown in FIG. As shown in FIG. 9 (2), the equivalent line length of the antenna may be extended by connecting capacitors in parallel. As shown in FIG. 9 (3), an equivalent line length may be extended by using a mixture of an inductor and a capacitor.

  An aerial wire wound in a loop or spiral may be used.

Industrial applicability

  Many conventional non-contact power transmission devices switch high frequency current by switching direct current on the power transmission side, so the voltage or current that is supplied to the load on the power receiving side is unstable and costly and inefficient constant voltage Had to depend on the circuit. In the present invention, by directly switching alternating current on the power transmission side, control can be performed using the phase of the alternating current on the power receiving side, and stabilization is possible with a simple hardware configuration and low-speed digital processing. Further, the larger the current flowing through the load, the wider the conduction angle of the bidirectional switch, and the current on the power transmission side is proportional to the voltage. As a result, it has been found that the power factor can be omitted because the power factor is improved. Industrial use can be expected by these.

It is a circuit diagram which shows the Example regarding the invention of Claim 1. It is a figure which shows the waveform of the circuit of FIG. It is a circuit diagram which shows the Example in connection with invention of Claim 2. It is a circuit diagram which shows the Example in connection with invention of Claim 3. It is a circuit diagram which shows the Example regarding the invention of Claim 4. It is a circuit diagram which shows the Example in connection with invention of Claim 5. It is a circuit diagram which shows the Example regarding the invention of Claim 6. It is a circuit diagram which shows the structural example of a bidirectional switch. It is a circuit diagram which shows an example of a conventional system.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 High frequency inverter 3, 6 Capacitor 4, 5 Antenna 7 Load 11, 12, 21, 22, 31, 32, 41, 42 MOSFET
13, 14, 23, 24, 33, 34, 43, 44 Insulation driver 15, 35 Diode 25, 45 Capacitor 26, 46 Diode 51 Diode 52 Capacitor 53, 54 Resistance 55 Insulation amplifier 56 Logic circuit 57 Control circuit 58, 59 Resistance 61, 62 IGBT
63, 64 Diode 71, 72 MOSFET
73, 74 Schottky barrier diode

[0034]
FIG. 1 is a circuit diagram showing an embodiment according to the first aspect of the present invention;
FIG. 2 is a diagram illustrating waveforms of the circuit of FIG.
FIG. 3 is a circuit diagram showing an embodiment according to the second aspect of the present invention;
4 is a circuit diagram showing an embodiment according to the invention of claim 3. FIG.
FIG. 5 is a circuit diagram showing an embodiment according to the invention as set forth in claim 4;
FIG. 6 is a circuit diagram showing an embodiment according to the invention as set forth in claim 5;
FIG. 7 is a circuit diagram showing an embodiment according to the invention as set forth in claim 6;
FIG. 8 is a circuit diagram showing a configuration example of a bidirectional switch.
FIG. 9 is a circuit diagram showing an example of extending the equivalent line length of an antenna.
FIG. 10 is a circuit diagram showing an example of a conventional method .
[Brief description of symbols]

Claims (6)

  An AC power source, an inverter that converts the AC current supplied from the AC power source into a high-frequency current by turning on and off, a first antenna that emits the high-frequency current output from the inverter into the air as electromagnetic field energy, and the first In a non-contact power transmission apparatus including a second antenna for receiving electromagnetic field energy emitted by an antenna and a load to which a high-frequency current generated in the second antenna is supplied, the second antenna is connected to the load. A first bidirectional switch is inserted in series on one line, a second bidirectional switch is inserted in series on the other line connecting the second antenna line and the load, and the first bidirectional switch A third bidirectional switch is connected between the second antenna side terminal of the second and the load side terminal of the second bidirectional switch, and the load side terminal of the first bidirectional switch A rectifying / smoothing circuit for connecting a fourth bidirectional switch between the second antenna side terminals of the second bidirectional switch to extract an AC envelope of high-frequency current generated in the second antenna, and the rectification A pulse is generated only during the period when the output voltage of the smoothing circuit exceeds the threshold value, and all of the first to fourth bidirectional switches are made to conduct in the positive direction, and the pulse generated after the pulse Each of the first to fourth bidirectional switches is turned on in the negative direction, and this is repeated to supply an alternating current to the load, and the threshold value is set to stabilize the alternating voltage applied to the load. A non-contact power transmission device, wherein a control circuit for controlling is added.   In order to stabilize the DC voltage applied to the load by repeatedly supplying the DC current to the load by repeating the logic circuit conducting the first to fourth bidirectional switches only in the positive direction every pulse. 2. The invention according to claim 1, wherein the threshold value is controlled.   3. The invention according to claim 1, wherein both the second bidirectional switch and the fourth bidirectional switch are replaced with capacitors.   3. The invention according to claim 2, wherein both the second bidirectional switch and the fourth bidirectional switch are replaced with diodes.   5. The invention according to claim 2, wherein the bidirectional switch is replaced with a unidirectional switch in which one MOSFET and one diode are connected in series.   6. The invention according to claim 1, wherein the control circuit controls the threshold value in order to stabilize a current applied to a load.

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