Inverter, rectifier circuit, and non-contact power supply system

Abstract

To provide a DE class inverter, a DE class synchronous rectifier circuit, and a non-contact power supply system that can perform an ideal and highly efficient operation, even when a load resistance value fluctuates.SOLUTION: An inverter 2 includes a passive circuit 20 between a switching circuit 11 and a load 5 for converting an input impedance Z to output of the switching circuit 11. The passive circuit 20 converts the input impedance Z into a reference impedance Z0 when the load 5 has a predetermined resistance value Rl0, with the input impedance Z being a reference impedance Z0 when switching voltages of a first switching element 12 and a second switching element 13 achieve ZVS and ZVDS during a time length τ of a dead time, and converts the input impedance Z to be within a range in which the switching voltage achieves ZVS during the time length τ of the dead time when the resistance value Rl of the load 5 varies from the predetermined resistance value Rl0.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an inverter, a rectifier circuit, and a contactless power supply system. [Background technology]

[0002] In recent years, electric vehicles and unmanned, autonomous electric mobility have attracted attention, and various research and development efforts have been made. In order to popularize such electric vehicles, etc., issues such as the cost and weight of the batteries installed, the length of power supply time, the difficulty of recycling, and increased labor costs have become problems. As one method for solving such issues, technology for unmanned, non-contact (wireless) power supply is being considered.

[0003] Such non-contact power supply methods include, for example, a magnetic field coupling method and an electric field coupling method. The magnetic field coupling method transmits power non-contact by transmitting power through space as magnetic field energy due to the connection of a magnetic field formed between a power transmitting coil and a power receiving coil. The electric field coupling method transmits power non-contact by transmitting power through space as electric field energy due to a capacitor formed between a power transmitting electrode and a power receiving electrode.

[0004] In order to transmit power contactlessly, high-frequency power is required. For this reason, a contactless power supply system uses, for example, an inverter that generates an AC voltage or an AC current from a DC voltage or a DC current. It is preferable that the inverter used has low loss and high efficiency.

[0005] As an inverter topology that has a theoretical efficiency of 100%, for example, a class E inverter is known (Patent Document 1). The class E inverter suppresses the occurrence of losses in the switching elements and achieves high efficiency by using zero voltage switching (ZVS) and zero voltage derivative switching (ZVDS) for the switching voltages in the switching elements.

[0006] However, due to the circuit configuration of the class E inverter, the switching element must be operated below the withstand voltage and withstand current of the semiconductor, so the power that can be output is limited. Also, the class E inverter uses a resonant filter to pass only the fundamental wave of the voltage or current output from the switching element, shapes it into a sine wave, and outputs it to the load. However, in order to supply a sine wave to the load while achieving ZVS and ZVDS in the switching element, it is necessary to provide a load inductor in series with the load. The class E inverter has a load Q (=ωL 0 / R l ω is the angular frequency, L 0 is the inductance of the load inductor, R l is the resistance value of the load. ) can only be reduced to 1.153. Therefore, the E-class inverter has an inductance L 0 However, a large load inductor is required, and the loss in the load inductor cannot be suppressed.

[0007] On the other hand, a DE class inverter is known as another topology of an inverter (Non-Patent Document 1). Here, an outline of the DE class inverter will be described with reference to Figs. 31 and 32. Fig. 31(a) is a circuit diagram showing a DE class inverter. Fig. 31(b) is a circuit diagram showing a first switching element 12 (first control signal Q 1 ) and the second switching element 13 (second control signal Q 2 ) and the voltage v applied to the first switching element 12 (the first capacitor 14 connected in parallel with the first switching element 12). 1 32 is a diagram showing a load Q characteristic with respect to the duty ratio of the first switching element 12 and the second switching element 13 in a DE-class inverter.

[0008] As shown in FIG. 31(a), the DE-class inverter is configured such that two switching elements (a first switching element 12 and a second switching element 13) connected in series are connected to a DC power source (in the example of FIG. 31(a), a DC voltage V DC). The DE class inverter provides a dead time during which the two switching elements (the first switching element 12 and the second switching element 13) are simultaneously turned off, and supplies a first control signal Q to the first switching element 12 so that the first switching element 12 and the second switching element 13 are alternately turned on at a predetermined duty ratio. 1 and applies a second control signal Q to the second switching element 13. 2 is applied.

[0009] As a result, a voltage v as shown in FIG. 31(b) is applied across the first switching element 12. 1 The DE class inverter generates a voltage v 1 The resonant capacitor 16 (capacitance C r ) and resonant inductor 17 (inductance L r ) connected in series, the resonant filter is used to shape the signal into a sine wave, and then the load 5 (resistance value R l ) to output.

[0010] Here, the DE class inverter is connected to a load 5 with a resistance value R l is the given resistance value R l0 When the switching voltages of the first switching element 12 and the second switching element 13 are set to ZVS and ZVDS, respectively, the DE-class inverter is designed to be able to suppress the occurrence of losses in the switching elements and achieve high efficiency, similar to the E-class inverter.

[0011] In addition, the DE class inverter alternately turns on two switching elements (the first switching element 12 and the second switching element 13) connected in series, which increases the voltage utilization of the semiconductor. This allows the DE class inverter to output a larger power than the E class inverter under certain conditions.

[0012] Furthermore, as shown in FIG. 32, the DE-class inverter is configured such that the first control signal Q 1and a second control signal Q applied to the second switching element 13. 2 The larger the duty ratio, the smaller the load Q. That is, for the same reason as in the E-class inverter, the DE-class inverter also has a load inductor 18 (with inductance L 0 ) is required, but a load Q (Q = ωL) that can achieve ZVS and ZVDS in the first switching element 12 and the second switching element 13 is required. 0 / R l ) is the first control signal Q applied to the first switching element 12 1 and a second control signal Q applied to the second switching element 13. 2 By setting the duty ratio to 0.29 or more, the value of the load Q can be set to 1.15 or less, which is smaller than the load Q of the E-class inverter. 1 and a second control signal Q applied to the second switching element 13. 2 Depending on the duty ratio of the load inductor 18, the inductance L required for the output load 5 is 0 can be made smaller than that of the class E inverter, so that the loss due to the load inductor 18 can be kept small.

[0013] In addition, the DE class inverter has the advantage that a full-bridge inverter can be easily constructed by combining two sets of two switching elements (first switching element 12 and second switching element 13) connected in series, and high output power can be easily achieved in a relatively small area.

[0014] For these reasons, there is a demand for adopting a DE class inverter as the inverter used in a contactless power supply system.

[0015] On the other hand, in a contactless power supply system, when the power transmitted contactlessly is used to drive a motor or charge a battery, the received high-frequency voltage or current cannot be used as is, and the high-frequency voltage or current may need to be rectified to a direct-current voltage or current. In this case, the contactless power supply system requires a rectifier circuit. It is preferable that this rectifier circuit has low loss and is highly efficient, similar to the inverter.

[0016] Conventionally, rectifier circuits have mainly used diodes. However, it is known that in rectifier circuits using diodes, a large energy loss occurs due to the forward bias voltage of the diode and the current flowing through the diode (Non-Patent Document 2). In addition, rectifier circuits using diodes generate heat due to the energy loss caused by the diodes, so a large heat sink is required. However, in contactless power transfer systems, there is a demand for both miniaturization of devices and high power output, and it has been difficult for rectifier circuits using diodes to meet this demand.

[0017] In recent years, it is expected that rectifier circuits will be able to reduce losses by using semiconductor switches (switching elements) such as field-effect transistors (FETs). One topology for such rectifier circuits is the class DE synchronous rectifier circuit.

[0018] The DE class synchronous rectifier circuit is configured as a topology in which the input and output of the DE class inverter shown in Fig. 31(a) are inverted. Therefore, in the following, the DE class synchronous rectifier circuit will be described using the same reference numerals as the DE class inverter shown in Fig. 31(a).

[0019] In the DE class synchronous rectifier circuit, an AC power supply is connected across the first switching element 12, which is one of two switching elements connected in series, a first switching element 12 and a second switching element 13. The DE class synchronous rectifier circuit provides a dead time during which the first switching element 12 and the second switching element 13 are simultaneously turned off, and transmits a first control signal Q to the first switching element 12 so as to alternately turn on the first switching element 12 and the second switching element 13 at a predetermined duty ratio. 1 and applies a second control signal Q to the second switching element 13. 2 At this time, a first control signal Q is applied so that the first switching element 12 and the second switching element 13 are turned on in synchronization with the AC voltage or AC current of the AC power supply connected to both ends of the first switching element 12. 1 and the second control signal Q 2 As a result, the class DE synchronous rectifier circuit rectifies the AC voltage or AC current input from the AC power supply and outputs it to the load as a DC voltage or DC current.

[0020] Here, the DE class synchronous rectifier circuit, like the DE class inverter, has a resistance value R l is the given resistance value R l0 When the switching voltages of the first switching element 12 and the second switching element 13 are set to ZVS and ZVDS, respectively, the DE-class synchronous rectifier circuit is designed to suppress the occurrence of loss in the switching elements and achieve high efficiency. [Prior art documents] [Patent documents]

[0021] [Patent Document 1] Patent Publication No. 2022-86784 [Non-patent literature]

[0022] [Non-Patent Document 1] MKKazimierczuk and D. Czarkowski, “Resonant Power Converters”, (US), Wiley, April 2011, pp. 382-404. [Non-Patent Document 2] T. Ohira, “Power efficiency and optimum load formulas on RF rectifiers featuring flow-angle equations”, IEICE Electronics Express, IEICE, 2013.6.10, vol.10, no.11, pp.1-9. Summary of the Invention [Problem to be solved by the invention]

[0023] Now, as mentioned above, the DE class inverter is connected to the load 5 with a resistance value R l is the given resistance value R l0 However, depending on the load state, for example, the charge rate if the load is a battery, or the operating state of the motor if the load is a motor, the resistance value R l fluctuates.

[0024] Here, as shown in FIG. 31(b), in the DE-class inverter designed as above, the load resistance R l fluctuates and the resistance R l0 When the first switching element 12 (first control signal Q 1 ) is turned on, the voltage v applied to the first switching element 12 1 becomes less than 0 volts, resulting in negative voltage switching. In addition, in this DE class inverter, the load resistance R l is the given resistance value R l0 When the first switching element 12 (first control signal Q 1) is turned on, the voltage v applied to the first switching element 12 1 becomes greater than 0 volts, resulting in positive voltage switching. This is because the second switching element 13 (second control signal Q 2 ) is also the same.

[0025] In this way, the resistance of the load R l is the given resistance value R l0 If the load resistance R of the DE class inverter is deviated from the normal range, a voltage other than 0 volts is applied to the first switching element 12 and the second switching element 13 at the switching timing, and thus a loss occurs in the first switching element 12 and the second switching element 13. l The problem was that the fluctuations in the output voltage meant that ideal, highly efficient operation could not be achieved. The same problem also occurs in class DE synchronous rectification circuits.

[0026] Here, Patent Document 1 discloses a technique for providing a passive circuit in an E-class inverter that converts the input impedance to a switching circuit so that the switching voltage of the switching element falls within a range in which ZVS is achieved for a fluctuating load resistance value. Patent Document 1 also discloses a technique for providing a passive circuit in an E-class synchronous rectifier circuit that converts the output impedance to a switching circuit so that the switching voltage of the switching element falls within a range in which ZVS is achieved for a fluctuating load resistance value.

[0027] However, in the case of a DE class inverter and a DE class synchronous rectifier circuit, the dead time is a parameter that affects the achievement of ZVS and ZVDS, but the E class inverter and the E class synchronous rectifier circuit have no concept of dead time. Therefore, the invention described in Patent Document 1 alone could not obtain ideal high-efficiency operation for a fluctuating load resistance value in the DE class inverter and the DE class synchronous rectifier circuit.

[0028] The present invention has been made in consideration of the above circumstances, and aims to provide an inverter and rectifier circuit having two switching elements connected in series and whose switching is controlled alternately with a dead time, which can perform highly efficient, ideal operation even when the load resistance value fluctuates, and to provide a contactless power supply system that uses at least one of these inverters and rectifier circuits. [Means for solving the problem]

[0029] In order to achieve this object, an inverter according to a first aspect of the present invention generates an AC voltage or AC current to be supplied to a load from a DC voltage or DC current, and outputs the AC voltage or AC current, the inverter having a series circuit in which a first capacitor to which a first switching element is connected in parallel and a second capacitor to which a second switching element is connected in parallel are connected in series, the inverter being configured to output an AC voltage or AC current based on a voltage or current generated at a connection point between the first capacitor and the second capacitor by alternately turning on the first switching element and the second switching element with the series circuit connected to the DC voltage or the DC current, and a passive circuit provided between the switching circuit and the load for converting an input impedance to an output of the switching circuit, the switching circuit generating a first control signal constituted by an on signal and an off signal for controlling the on / off of the first switching element at a predetermined duty ratio, and a second control signal constituted by an on signal and an off signal for controlling the on / off of the second switching element at the predetermined duty ratio. , the on signal of the first control signal and the on signal of the second control signal are generated alternately in time, and a dead time during which both the first control signal and the second control signal become the off signal is provided between the on signal of the first control signal and the on signal of the second control signal, and the passive circuit is configured to convert the input impedance to the reference impedance when the switching voltages of the first switching element and the second switching element, which are determined based on configurations and setting values ​​of each element provided in the switching circuit and a circuit connected to the switching circuit including the load, and the length of the dead time, achieve zero voltage switching and zero voltage differential switching during the length of the dead time, when the load has a predetermined resistance value, and to convert the input impedance so that the input impedance becomes the reference impedance when the resistance value of the load varies from the predetermined resistance value, so that the switching voltage is within a range within which the zero voltage switching is achieved during the length of the dead time.

[0030] Here, the expression "AC voltage or AC current" means that the present invention is understood by focusing on one of them, and it goes without saying that, for example, when the present invention is understood as AC voltage, AC current is not excluded, and the two are inseparable physical concepts. The same applies to the expressions "voltage or current" and "DC voltage or DC current." This concept is applied to everything in the present invention.

[0031] The inverter according to the second aspect is the inverter according to the first aspect, wherein the passive circuit is configured as a circuit that satisfies an impedance parameter that can perform impedance conversion from a real axis load variation geodesic curve, which depicts the variation in the resistance value of the load on a Smith chart, to a zero voltage switching geodesic curve, which depicts the input impedance that achieves the zero voltage switching during the time length of the dead time, on the Smith chart.

[0032] In a third aspect of the inverter, in the inverter of the second aspect, the impedance parameters of the passive circuit are calculated such that the impedance transformation from the real axis load variation geodesic to the zero voltage switching geodesic is performed by a Moebius transformation using at least one of zooming in / out, rotation, and translation in the vertical axis direction on an impedance plane whose vertical axis is represented by reactance components and whose horizontal axis is represented by resistance components.

[0033] An inverter according to a fourth aspect is the inverter according to any one of the first to third aspects, wherein the passive circuit is formed of an inductor and a capacitor.

[0034] A rectifier circuit according to a fifth aspect rectifies an AC voltage or an AC current and outputs a DC voltage or a DC current to a load, and includes a series circuit in which a first capacitor to which a first switching element is connected in parallel and a second capacitor to which a second switching element is connected in parallel are connected in series, and a switching circuit outputs the DC voltage or the DC current by alternately turning on the first switching element and the second switching element under a predetermined condition in a state in which a voltage or current based on the AC voltage or the AC current is supplied to a connection point between the first capacitor and the second capacitor, and a passive circuit is provided between an input end of the rectifier circuit to which the AC voltage or the AC current is input and the switching circuit, for converting an output impedance to the input of the switching circuit, and and a control unit which generates the first control signal and the second control signal such that the on signal of the first control signal and the on signal of the second control signal are generated alternately in time, a dead time during which both the first control signal and the second control signal become the off signal is provided between the on signal of the first control signal and the on signal of the second control signal, and a predetermined phase difference is formed between the first control signal and the second control signal and the AC voltage or the AC current input to the rectifier circuit, and the passive circuit converts the output impedance to the reference impedance when the switching voltages of the first switching element and the second switching element, which are determined based on configurations and setting values ​​of each element provided in the switching circuit and a circuit connected to the switching circuit including the load, and the time length of the dead time, so that the output impedance becomes the reference impedance when the load has a predetermined resistance value, and when the resistance value of the load varies from the predetermined resistance value,The output impedance is converted so that the switching voltage is within a range that achieves the zero voltage switching during the dead time.

[0035] A rectifier circuit according to a sixth aspect is the rectifier circuit according to the fifth aspect, wherein the specified phase difference is determined by whether the input to the rectifier circuit is a constant voltage or a constant current, whether the output to the load is a constant voltage or a constant current, and whether the off-diagonal components of the Z parameters or the off-diagonal components of the Y parameters representing the passive circuit are positive or negative numbers.

[0036] A rectifier circuit according to a seventh aspect is the rectifier circuit according to the fifth or sixth aspect, wherein the control unit detects the AC voltage or the AC current input to the rectifier circuit, and based on the detection result, generates the first control signal and the second control signal such that the phase difference between the first control signal and the second control signal and the AC voltage or the AC current input to the rectifier circuit becomes the predetermined phase difference.

[0037] A rectifier circuit according to an eighth aspect is the rectifier circuit according to the fifth or sixth aspect, wherein the control unit detects the AC voltage or the AC current input to the rectifier circuit to generate the first control signal and the second control signal, and adjusts the phase of the first control signal and the second control signal so that the DC voltage or the DC current becomes a predetermined target value.

[0038] A rectifier circuit according to a ninth aspect is the rectifier circuit according to the fifth or sixth aspect, wherein the control unit detects the AC voltage or the AC current input to the rectifier circuit to generate the first control signal and the second control signal, and adjusts the phase of the first control signal and the second control signal so that the ratio between the AC voltage and the DC voltage, the ratio between the AC voltage and the DC current, the ratio between the AC current and the DC current, or the ratio between the AC current and the DC voltage becomes a predetermined target value.

[0039] A contactless power supply system according to a tenth aspect has the inverter according to any one of the first to fourth aspects on a power supply side, and is coupled to a rectifier circuit via a coupler.

[0040] A contactless power supply system according to an eleventh aspect has the rectifier circuit according to any one of the fifth to ninth aspects on a power receiving side, and is coupled to an inverter via a coupler.

[0041] A contactless power supply system according to a twelfth aspect has an inverter according to any one of the first to fourth aspects on a power supplying side, and a rectifier circuit according to any one of the fifth to ninth aspects on a power receiving side, and is configured so that the inverter and the rectifier circuit are coupled by a coupler. Effect of the Invention

[0042] According to the power transmission device of the first aspect, in a state where a DC voltage or a DC current is supplied to a series circuit of a first capacitor and a second capacitor (i.e., a series circuit of a first switching element and a second switching element) constituting a switching circuit, a first control signal for controlling the on / off of the first switching element with a predetermined duty ratio and a second control signal for controlling the on / off of the second switching element with the predetermined duty ratio are input to the switching circuit. The on signal of the first control signal and the on signal of the second control signal are generated alternately. As a result, an AC voltage or an AC current based on a voltage or a current generated at a connection point between the first capacitor and the second capacitor (i.e., a connection point between the first switching element and the second switching element) is output from the switching circuit. The inverter can output an AC voltage or an AC current to a load based on the AC voltage or the AC current output from the switching circuit.

[0043] Here, a dead time during which both the first control signal and the second control signal are OFF is provided between the ON signal of the first control signal and the ON signal of the second control signal. The switching voltages of the first switching element and the second switching element are determined based on the length of this dead time and the configurations and setting values ​​of each element provided in the switching circuit and the circuit connected to the switching circuit including the load.

[0044] Meanwhile, a passive circuit is provided between the switching circuit and the load, and the input impedance to the output of the switching circuit is converted by the passive circuit. Specifically, when the load has a predetermined resistance value, the input impedance to the output of the switching circuit is converted to a reference impedance by the passive circuit. Here, the reference impedance is the input impedance to the output of the switching circuit when the switching voltages of the first switching element and the second switching element achieve zero voltage switching and zero voltage differential switching during the time length of the dead time. As a result, when the load has a predetermined resistance value, the switching voltages of the first switching element and the second switching element achieve zero voltage switching and zero voltage differential switching, so that the occurrence of losses in the first switching element and the second switching element can be suppressed.

[0045] In addition, even if the load varies from a predetermined resistance value, the input impedance to the output of the switching circuit is converted by the passive circuit so that the switching voltages of the first switching element and the second switching element achieve zero voltage switching during the dead time. As a result, even if the load varies from a predetermined resistance value, the switching voltages of the first switching element and the second switching element achieve at least zero voltage switching, so that the occurrence of losses in the first switching element and the second switching element can be suppressed in the same way as when the load has a predetermined resistance value. Therefore, there is an effect that an inverter having two switching elements connected in series, whose switching is controlled alternately with a dead time, can be provided, which can perform ideal operation with high efficiency even when the resistance value of the load varies.

[0046] The inverter according to the second aspect has the following effect in addition to the effect of the inverter according to the first aspect. That is, when an impedance parameter is obtained that can perform impedance conversion from a real axis load variation geodesic curve on a Smith chart that shows the variation of the resistance value of the load to an input impedance to an output of a switching circuit that achieves zero voltage switching as a switching voltage during the time length of the dead time to a zero voltage switching geodesic curve on a Smith chart, the passive circuit is configured as a circuit that satisfies the impedance parameter. That is, by simply obtaining an impedance parameter that can perform impedance conversion from the real axis load variation geodesic curve to the zero voltage switching geodesic curve, it is possible to reliably construct a passive circuit that can convert the input impedance to the output of a switching circuit into an input impedance that can achieve zero voltage switching with the switching voltages of the first switching element and the second switching element during the time length of the dead time, in response to the variation of the resistance value of the load.

[0047] The inverter according to the third aspect has the following effect in addition to the effect of the inverter according to the second aspect: That is, the impedance parameters of the passive circuit are obtained so that the impedance transformation from the real axis load variation geodesic to the zero voltage switching geodesic is performed by a Moebius transformation using at least one of enlargement / reduction, rotation, and translation in the vertical axis direction on an impedance plane whose vertical axis is represented by reactance components and whose horizontal axis is represented by resistance components.

[0048] The real axis load variation geodesic is represented by a straight line on the impedance plane, and the zero voltage switching geodesic is represented by a semicircle on the impedance plane. On the other hand, the Möbius transformation allows mapping from a circle to a circle. Also, since a straight line can be regarded as a circle with an infinite radius, the Möbius transformation also allows mapping from a straight line to a circle. The passive circuit is constructed so as to realize impedance conversion from the real axis load variation geodesic, which represents the resistance value of the load as a straight line, to the zero voltage switching geodesic, which represents the input impedance to the output of the switching circuit as a semicircle, by such a Möbius transformation. This makes it possible to construct a passive circuit that can reliably convert the input impedance to the output of the switching circuit to an input impedance that achieves zero voltage switching in the first switching element and the second switching element during the time length of the dead time, for the resistance value of the load that varies.

[0049] Furthermore, since the Moebius transformation performed in the passive circuit uses at least one of the following: enlargement / reduction, rotation, and translation in the vertical axis direction (the direction in which only the reactance component changes), the Moebius transformation can be configured using inductors and capacitors. In other words, the passive circuit can be configured without using resistors, so losses in the passive circuit can be suppressed. Therefore, even if a passive circuit is provided, there is an effect that the high efficiency of the inverter can be maintained.

[0050] According to the inverter of the fourth aspect, in addition to the effects of the inverter of any one of the first to third aspects, since the passive circuit is composed of an inductor and a capacitor, it is possible to suppress the occurrence of loss in the passive circuit, and therefore, even if a passive circuit is provided, it is possible to maintain high efficiency of the inverter.

[0051] According to the rectifier circuit of the fifth aspect, in a state where a voltage or current based on an AC voltage or AC current is supplied to a connection point (i.e., a connection point between the first switching element and the second switching element) between the first capacitor and the second capacitor in a series circuit (i.e., a series circuit between the first switching element and the second switching element) of the first capacitor and the second capacitor constituting the switching circuit, a first control signal for controlling the on / off of the first switching element at a predetermined duty ratio and a second control signal for controlling the on / off of the second switching element at the predetermined duty ratio are input to the switching circuit. The first control signal and the second control signal are generated by the control unit as follows. That is, the on signal of the first control signal and the on signal of the second control signal are generated alternately in time, a dead time during which both the first control signal and the second control signal are off signals are provided between the on signal of the first control signal and the on signal of the second control signal, and the first control signal and the second control signal are generated such that there is a predetermined phase difference between the AC voltage or AC current input to the rectifier circuit. The generated first control signal and the second control signal are output from the control unit to the switching circuit. As a result, the first switching element and the second switching element are alternately turned on with a constant phase difference with respect to the AC voltage or AC current input to the rectifier circuit, so that the AC voltage or AC current input to the rectifier circuit is rectified by the switching circuit, and a DC voltage or DC current can be output from the switching circuit.

[0052] Here, the switching voltages of the first switching element and the second switching element are determined based on the length of the dead time provided between the on signal of the first control signal and the on signal of the second control signal, as well as the configuration and setting values ​​of each element provided in the switching circuit and a circuit connected to the switching circuit including a load.

[0053] On the other hand, a passive circuit is provided between the input end of the rectifier circuit to which an AC voltage or AC current is input and the switching circuit, and the passive circuit converts the output impedance to the input of the switching circuit. Specifically, when the load has a predetermined resistance value, the output impedance to the input of the switching circuit is converted to a reference impedance by the passive circuit. Here, the reference impedance is the output impedance to the input of the switching circuit when the switching voltages of the first switching element and the second switching element achieve zero voltage switching and zero voltage differential switching during the dead time. As a result, when the load has a predetermined resistance value, the switching voltages of the first switching element and the second switching element achieve zero voltage switching and zero voltage differential switching, so that the occurrence of losses in the first switching element and the second switching element can be suppressed.

[0054] In addition, even if the load varies from a predetermined resistance value, the input impedance to the output of the switching circuit is converted by the passive circuit so that the switching voltages of the first switching element and the second switching element are within a range in which zero voltage switching is achieved during the dead time. As a result, even if the load varies from a predetermined resistance value, the switching voltages of the first switching element and the second switching element at least achieve zero voltage switching, so that the occurrence of losses in the first switching element and the second switching element can be suppressed in the same way as when the load has a predetermined resistance value. Therefore, there is an effect that a rectifier circuit having two switching elements connected in series and whose switching is controlled alternately with a dead time can be provided, which can perform ideal operation with high efficiency even when the resistance value of the load varies.

[0055] The rectifier circuit according to the sixth aspect has the following effect in addition to the effect of the rectifier circuit according to the fifth aspect. That is, the predetermined phase difference between the first control signal and the second control signal and the AC voltage or AC current input to the rectifier circuit is determined by whether the input to the rectifier circuit is a constant voltage or a constant current, whether the output to the load is a constant voltage or a constant current, and whether the off-diagonal components of the Z parameter or the off-diagonal components of the Y parameter representing the passive circuit are positive or negative. This has the effect of realizing a rectifier circuit that can output a constant-voltage DC voltage or a constant-current DC current to a load when a constant-voltage AC voltage or a constant-current AC current is input to the rectifier circuit.

[0056] The rectifier circuit according to the seventh aspect has the following effect in addition to the effect of the rectifier circuit according to the fifth or sixth aspect. That is, the control unit detects the AC voltage or AC current input to the rectifier circuit, and based on the detection result, the first control signal and the second control signal are generated so that the phase difference between the first control signal and the second control signal and the AC voltage or AC current input to the rectifier circuit is a predetermined phase difference. As a result, even if a phase shift occurs in the AC voltage or AC current input to the rectifier circuit, the phase difference between the AC voltage or AC current and the first control signal and the second control signal is maintained at a predetermined phase difference. Therefore, zero voltage switching in the first switching element and the second switching element can be maintained, which has the effect of maintaining high efficiency operation in the rectifier circuit.

[0057] The rectifier circuit according to the eighth aspect has the following effect in addition to the effect of the rectifier circuit according to the fifth or sixth aspect. That is, the control unit detects the AC voltage or AC current input to the rectifier circuit and generates the first control signal and the second control signal. At this time, the control unit adjusts the phases of the first control signal and the second control signal so that the DC voltage or DC current becomes a predetermined target value. This has the effect of keeping the magnitude of the DC voltage or DC current output from the rectifier circuit constant even if the constant voltage characteristic of the AC voltage or the constant current characteristic of the AC current input to the rectifier circuit is lost and there is a fluctuation in amplitude.

[0058] The rectifier circuit according to the ninth aspect has the following effect in addition to the effect of the rectifier circuit according to the fifth or sixth aspect. That is, the control unit detects the AC voltage or AC current input to the rectifier circuit and generates the first control signal and the second control signal. At this time, the control unit adjusts the phases of the first control signal and the second control signal so that the ratio of the AC voltage to the DC voltage, the ratio of the AC voltage to the DC voltage, the ratio of the AC current to the DC current, or the ratio of the AC current to the DC voltage becomes a predetermined target value. As a result, when the constant voltage characteristic of the AC voltage or the constant current characteristic of the AC current input to the rectifier circuit is lost and the amplitude fluctuates, the magnitude of the DC voltage or the DC current can be changed in accordance with the fluctuation, while maintaining zero voltage switching in the first switching element and the second switching element. Therefore, there is an effect that the rectifier circuit can maintain high efficiency operation.

[0059] According to the contactless power supply system of the tenth aspect of the present invention, an AC voltage or an AC current is generated by the inverter of any one of the first to fourth aspects provided on the power supply side, and the AC voltage or the AC current is supplied to the rectifier circuit in a contactless manner via a coupler. This allows the contactless power supply system to obtain the same effects as those obtained by the inverter provided on the power supply side.

[0060] According to the contactless power supply system of the eleventh aspect, an AC voltage or AC current output from an inverter is received contactlessly via a coupler by a rectifier circuit of any one of the fifth to ninth aspects provided on a power receiving side. Then, a DC voltage or DC current generated by the rectifier circuit is output to a load. This allows the contactless power supply system to obtain the same effect as that achieved by a rectifier circuit provided on the power receiving side.

[0061] According to the contactless power supply system of the twelfth aspect, an AC voltage or AC current is generated by an inverter of any one of the first to fourth aspects provided on the power supply side, and the AC voltage or AC current is supplied contactlessly to a rectifier circuit of any one of the fifth to ninth aspects via a coupler. Then, a DC voltage or DC current generated by the rectifier circuit is output to a load. This allows the contactless power supply system to obtain the same effect as that of an inverter provided on the power supply side, and also to obtain the same effect as that of a rectifier circuit provided on the power receiving side. [Brief description of the drawings]

[0062] [Figure 1] 1 is a schematic configuration diagram of a contactless power supply system according to an embodiment of the present invention. [Diagram 2] 1A is a circuit diagram of an inverter of the contactless power supply system, and FIG. 1B is a diagram showing the switching states of a first switching element and a second switching element that constitute the inverter, and the time progression of the voltage applied to the first switching element. [Diagram 3] 13 is a Z-plane diagram showing the ZVS geodesic curve, the ZVDS geodesic curve, and the ZVS / ZVDS load point at each duty ratio set in the first control signal of the first switching element and the second control signal of the second switching element of the inverter, where (a) shows the case where the duty ratio is 0.05, (b) shows the case where the duty ratio is 0.1, (c) shows the case where the duty ratio is 0.15, (d) shows the case where the duty ratio is 0.2, (e) shows the case where the duty ratio is 0.25, and (f) shows the case where the duty ratio D=0.3. [Figure 4] 13 is a Z-plane view of the same, where (a) shows the case where the duty ratio is 0.35, (b) shows the case where the duty ratio is 0.4, and (c) shows the case where the duty ratio is 0.45. [Diagram 5] (a) is a Smith chart showing the ZVS geodesic curve and the real axis load variation geodesic curve of the inverter, (b) is a diagram showing the circle-circle transformation of the Möbius transformation on the Z plane, and (c) is a diagram showing the line-circle transformation of the Möbius transformation on the Z plane. [Figure 6] 1A is a circuit diagram showing a passive circuit that realizes parallel translation in the vertical axis direction (reactance (X) axis direction) on the Z plane as a circle-circle transformation; 1B is a circuit diagram showing a passive circuit that realizes enlargement / reduction as a circle-circle transformation; and 1C is a circuit diagram showing a passive circuit that realizes rotation as a circle-circle transformation. [Figure 7] FIG. 7(a) is a diagram showing the Z parameters of a passive circuit provided in the inverter, FIG. 7(b) is a diagram showing an example of the correspondence between three points on a real axis load variation geodesic curve and three points on a ZVS geodesic curve to be obtained by impedance conversion using the passive circuit, and FIG. 7(c) is a diagram showing another example of the correspondence. [Figure 8] 1A is a diagram showing a circuit topology that realizes a Z parameter in which all components are composed of reactance only, and FIG. 1B is a diagram showing a circuit topology that realizes a Y parameter in which all components are composed of susceptance only. [Figure 9] FIG. 8 is a diagram showing a circuit topology of a passive circuit that realizes the impedance transformation shown in FIG. 7(b). [Figure 10] FIG. 8 is a diagram showing a circuit topology of a passive circuit that realizes the impedance transformation shown in FIG. [Figure 11] FIG. 1A is a circuit diagram showing an inverter having a passive circuit according to design example 1, and FIG. 1B is a diagram showing the values ​​of each parameter of the inverter used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Figure 12] FIG. 13 is a diagram showing a simulation result of the inverter according to the design example 1. [Figure 13] 1A is a circuit diagram showing an inverter having a passive circuit according to design example 2, and FIG. 1B is a diagram showing the values ​​of each parameter of the inverter used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Figure 14] FIG. 13 is a diagram showing a simulation result of the inverter according to the design example 2. [Figure 15]1A is a circuit diagram showing an inverter having a passive circuit according to design example 3, and FIG. 1B is a diagram showing the values ​​of each parameter of the inverter used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Figure 16] FIG. 13 is a diagram showing a simulation result of the inverter according to the design example 3. [Figure 17] 1A is a circuit diagram showing an inverter having a passive circuit according to design example 4, and FIG. 1B is a diagram showing the values ​​of each parameter of the inverter used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Figure 18] FIG. 13 is a diagram showing a simulation result of the inverter according to the design example 4. [Figure 19] 1A is a circuit diagram showing an inverter having a passive circuit according to design example 5, and FIG. 1B is a diagram showing the values ​​of each parameter of the inverter used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Figure 20] FIG. 13 is a diagram showing a simulation result of the inverter according to the design example 5. [Figure 21] FIG. 2 is a circuit diagram of a rectifier circuit used in the contactless power supply system. [Figure 22] 1A is a circuit diagram showing a rectifier circuit having a passive circuit according to design example 6, and FIG. 1B is a diagram showing the values ​​of each parameter of the rectifier circuit used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Diagram 23] FIG. 13 is a diagram showing a simulation result of the rectifier circuit according to design example 6. [Figure 24] 13(a) is a circuit diagram showing a rectifier circuit having a passive circuit according to design example 7, and FIG. 13(b) is a diagram showing the values ​​of each parameter of the rectifier circuit used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Diagram 25] FIG. 13 is a diagram showing a simulation result of the rectifier circuit according to design example 7. [Figure 26]13(a) is a circuit diagram showing a rectifier circuit having a passive circuit according to design example 8, and FIG. 13(b) is a diagram showing the values ​​of each parameter of the rectifier circuit used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Figure 27] FIG. 13 is a diagram showing a simulation result of the rectifier circuit according to design example 8. [Figure 28] 13(a) is a circuit diagram showing a rectifier circuit having a passive circuit according to design example 9, and FIG. 13(b) is a diagram showing the values ​​of each parameter of the rectifier circuit used in designing the passive circuit and the values ​​of each parameter of the passive circuit obtained by the design. [Figure 29] FIG. 13 is a diagram showing a simulation result of the rectifier circuit according to design example 9. [Diagram 30] 11A and 11B are diagrams for explaining a modified example of a method for generating a first control signal for controlling a first switching element and a second control signal for controlling a second switching element of a switching circuit of a rectifier circuit. [Diagram 31] FIG. 1A is a circuit diagram showing a conventional DE-class inverter, and FIG. 1B is a diagram showing the switching states of the first and second switching elements that constitute the DE-class inverter, and the time progression of the voltage applied to the first switching element. [Diagram 32] 1 is a diagram showing load Q characteristics with respect to the duty ratio of a first switching element and a second switching element in a DE-class inverter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0063] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the accompanying drawings. Note that each of the embodiments described below shows a preferred specific example of the present invention. Therefore, the numerical values, shapes, materials, components, and the arrangement and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims showing the highest concept of the present invention will be described as optional components. In addition, in each drawing, the same reference numerals are given to substantially the same configurations, and duplicated descriptions are omitted or simplified.

[0064] <1. Overall composition> First, an overview of a contactless power supply system 1 according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of the contactless power supply system 1.

[0065] The non-contact power supply system 1 includes a load 5 (resistance value R l The system is configured to supply power to a power source (transmitter) in a non-contact (wireless) manner, and includes an inverter 2 provided on the power supply side, a rectifier circuit 3 provided on the power receiving side, and a coupler 4 that couples the inverter 2 and the rectifier circuit 3.

[0066] The inverter 2 is a circuit that generates and outputs high-frequency power (AC voltage or AC current) from a DC power supply (DC voltage or DC current) to be supplied (fed) to a load 5. The inverter 2 is configured with a DE-class inverter as its topology.

[0067] As mentioned above, the DE class inverter operates with the resistance value R l is the given resistance value R l0 If so, the switching voltage in the switching element can be configured to achieve zero voltage switching (hereinafter referred to as "ZVS") and zero voltage differential switching (hereinafter referred to as "ZVDS"). This allows the DE class inverter to suppress losses due to the switching elements, thereby achieving high efficiency.

[0068] In addition, a DE class inverter can output greater power than a E class inverter under certain conditions, and a full-bridge inverter can be easily constructed, making it easy to achieve high output power in a small area.

[0069] Furthermore, the DE-class inverter achieves ZVS and ZVDS in the switching elements while outputting a sine wave (fundamental wave) to the load 5 through a resonant filter (a circuit in which a resonant capacitor 16 and a resonant inductor 17 are connected in series as shown in FIG. 2(a)). In order to do so, a load inductor (load inductor 18 (inductance L 0 The DE class inverter requires a load Q (=ωL 0 / R l ), but the larger the duty ratio D of the control signal applied to the switching element, the smaller the inductance L of the load inductor 18 (see FIG. 31(a)) required for the load 5. 0 Therefore, the DE class inverter is a suitable topology for the inverter 2 of the wireless power transfer system 1 that requires a large amount of power to be supplied to the load 5.

[0070] The rectifier circuit 3 is a circuit that rectifies the received high-frequency power (AC voltage or AC current) and outputs a DC voltage or DC current to the load 5. The rectifier circuit 3 has a topology formed of a DE-class synchronous rectifier circuit.

[0071] As described above, the DE-class synchronous rectifier circuit is similar to the DE-class inverter in that the resistance value R l is the given resistance value R l0 If so, the switching voltage of the switching element can be configured to achieve ZVS and ZVDS. As a result, the DE-class synchronous rectifier circuit can suppress losses due to the switching element, and can achieve high efficiency, making it suitable as a topology for the rectifier circuit 3 used in the wireless power transfer system 1.

[0072] The coupler 4 is a coupler that couples the inverter 2 on the power supply side and the rectifier circuit 3 on the power receiving side in a non-contact manner. The coupler 4 supplies high-frequency power (AC voltage or AC current) output from the inverter 2 to the rectifier circuit 3 in a non-contact manner. The coupler 4 may be a magnetic field coupling type using coils provided on each of the power transmitting side and the power receiving side, or an electric field coupling type using electrodes provided on each of the power transmitting side and the power receiving side. However, the coupler 4 may have any configuration as long as it can supply high-frequency power from the inverter 2 to the rectifier circuit 3 in a non-contact manner.

[0073] The contactless power supply system 1 configured in this manner operates as follows. When a DC voltage or DC current is supplied to the inverter 2, high frequency power (AC voltage or AC current) is generated by the inverter 2. The high frequency power generated by the inverter 2 is supplied to the rectifier circuit 3 in a contactless manner by the coupler 4. The high frequency power received by the rectifier circuit 3 is rectified by the rectifier circuit 3 to generate a DC voltage or DC current. The DC voltage or DC current generated by the rectifier circuit 3 is output to the load 5. In this way, the contactless power supply system 1 can supply power to the load 5 in a contactless manner.

[0074] <2. Inverter configuration> Next, the configuration of the inverter 2 used in the contactless power supply system 1 will be described with reference to Fig. 2. Fig. 2(a) is a circuit diagram of the inverter 2, and Fig. 2(b) is a circuit diagram of the first switching element 12 (which is connected to the first control signal Q 1 ) and the second switching element 13 (second control signal Q 2 ) and the voltage v applied to the first switching element 12 (the first capacitor 14 connected in parallel with the first switching element 12). 1 In order to simplify the explanation of the inverter 2, the coupler 4, the rectifier circuit 3, and the load 5 in FIG. 1 , which are provided after the output of the inverter 2 in the contactless power supply system 1, are collectively referred to as one load 5 (with a resistance value Rl ) will be explained as follows.

[0075] The inverter 2 is configured to include a switching circuit 11 that forms a DE class inverter, and a passive circuit 20 provided between the switching circuit 11 and the load 5.

[0076] The switching circuit 11 has a DC voltage V DC The switching circuit 11 is a circuit to which a DC voltage source 10 is connected, and which generates and outputs an AC voltage or an AC current from the DC voltage source 10. Note that a DC current source 10a may be connected to the input terminal of the switching circuit 11 instead of the DC voltage source 10 (see Figs. 15 and 17). The AC voltage or AC current generated by the switching circuit 11 is output from the output terminal to a load 5 via a passive circuit 20.

[0077] The switching circuit 11 includes a smoothing capacitor 19 (capacitance C f ), a first switching element 12, a second switching element 13, a first capacitor 14 (capacitance C) to which the first switching element 12 is connected in parallel, a second capacitor 15 (capacitance C) to which the second switching element 13 is connected in parallel, and a resonant capacitor 16 (capacitance C r ) and resonant inductor 17 (inductance L r )

[0078] Smoothing capacitor 19 is a large-capacity capacitor connected in parallel to DC voltage source 10 for the purpose of supplying a stable DC voltage to switching circuit 11, and plays a role of smoothing the voltage output from DC voltage source 10. Smoothing capacitor 19 also plays a role of suppressing surge voltages generated by turning on / off first switching element 12 and second switching element 13, and preventing damage to first switching element 12 and second switching element 13.

[0079] First capacitor 14 and second capacitor 15 are connected in series to form a series circuit. This series circuit is connected in parallel to DC voltage source 10 such that first capacitor 14 is connected to the negative side of DC voltage source 10 and second capacitor 15 is connected to the positive side of DC voltage source 10.

[0080] This means that first switching element 12 connected in parallel to first capacitor 14 and second switching element 13 connected in parallel to second capacitor 15 also constitute a series circuit in which these are connected in series. This series circuit means that first switching element 12 is connected to the negative side of DC voltage source 10 and second switching element 13 is connected to the positive side of DC voltage source 10, and is connected in parallel to DC voltage source 10. In addition, the connection point between first switching element 12 and second switching element 13 is the same (same potential) as the connection point between first capacitor 14 and second capacitor 15.

[0081] The first switching element 12 and the second switching element 13 are configured with semiconductor switches such as transistors, and for example, a field effect transistor (FET) such as an n-type MOSFET (Metal-Oxide-Semiconductor Field-Effect-Transistor) is used. In order to control the on / off of the first switching element 12 and the second switching element 13, the switching circuit 11 is provided with a first control signal Q 1 and the second control signal Q 2 The first control signal Q 1 is a control signal that controls the on / off of the first switching element 12 at a predetermined duty ratio D. 2 is a control signal that controls the on / off of the second switching element 13 at a predetermined duty ratio D.

[0082] FIG. 2(b) shows the first control signal Q when n-type MOSFETs are used as the first switching element 12 and the second switching element 13. 1and the second control signal Q 2 The waveform of the first control signal Q 1 and the second control signal Q 2 is generated by a control unit (not shown) so as to have the waveform shown in FIG. 2(b), and the first control signal Q 1 is applied to the gate of the n-type MOSFET constituting the first switching element 12, and a second control signal Q 2 is input to the gate of the n-type MOSFET that constitutes the second switching element 13.

[0083] That is, the first control signal Q 1 and the second control signal Q 2 are generated as signals for controlling the on / off of the first switching element 12 or the second switching element 13 in a switching period T (switching frequency f=1 / T). 1 an ON signal for turning on the first switching element 12 in the 2 The ON signal for turning on the second switching element 13 in the ON state is generated alternately in time.

[0084] Also, the first control signal Q 1 On signal and second control signal Q 2 Between the on signal and the first control signal Q 1 and the second control signal Q 2 There is a dead time when both signals are off. 1 The off signal is a signal for turning off the first switching element 12, and the second control signal Q 2 The off signal is a signal for turning off the second switching element 13. Therefore, in the switching circuit 11, both the first switching element 12 and the second switching element 13 are turned off during the dead time period.

[0085] It should be noted that p-type MOSFETs may be used as the first switching element 12 and the second switching element 13. In this case, the polarity of the gate voltage required to turn on the switching element is opposite to that of an n-type MOSFET, so that the first control signal Q 1 and the second control signal Q2 In other words, when n-type MOSFETs are used as the first switching element 12 and the second switching element 13, as shown in FIG. 2(b), the waveform of the first control signal Q 1 and the second control signal Q 2 (Voltage of the on signal)>(First control signal Q 1 and the second control signal Q 2 When p-type MOSFETs are used as the first switching element 12 and the second switching element 13, the voltage of the off signal of the first control signal Q 1 and the second control signal Q 2 (Voltage of the on signal) < (First control signal Q 1 and the second control signal Q 2 (voltage of the off signal).

[0086] To summarize the above, the first control signal Q 1 and the second control signal Q 2 As shown in FIG. 2(b), where the length of the dead time is τ, is generated, for example, as follows during the time period from 0 to T (T is a switching period):

[0087] First, the time from 0 to τ is a dead time, and the first control signal Q 1 and the second control signal Q 2 Then, during the time τ to T / 2, the second control signal Q 2 remains an off signal, the first control signal Q 1 Then, the period from T / 2 to T / 2+τ is again a dead time, and the first control signal Q 1 and the second control signal Q 2 Both of the first control signal Q 1 remains an off signal, the second control signal Q 2 is an ON signal.

[0088] In addition, the first control signal Q 1 and the second control signal Q 2 Duty ratio D(=T on / (T on +T off), where T on is the duration of the on signal, T off is the duration of the off signal. ) is determined by the switching period T and the duration τ of the dead time, as shown in the following formula (A).

[0089] D=(T-2τ) / 2T=(π-φ) / 2π (A) Here, φ is a variable that represents the magnitude (angle) of the phase that advances during the dead time length τ with respect to the switching period T, and is defined as φ=ωτ=2πτ / T (ω is the switching angular frequency, and ω=2π / T).

[0090] Such a first control signal Q 1 and the second control signal Q 2 is input to the switching circuit 11, the first switching element 12 is turned on / off by the first control signal Q 1 The second switching element 13 is turned on / off by a second control signal Q 2 By controlling the voltage v generated across the first capacitor 14 (i.e., the first switching element 12), 1 will result in a waveform as shown in Figure 2(b).

[0091] The voltage v generated across the first capacitor 14 (i.e., the first switching element 12) 1 is the switching voltage of the first switching element 12, and is the voltage v generated at the connection point between the first capacitor 14 and the second capacitor 15 (i.e., the connection point between the first switching element 12 and the second switching element 13). 1 In other words, a resonant filter formed by connecting a resonant capacitor 16 and a resonant inductor 17 in series is connected to the connection point between the first capacitor 14 and the second capacitor 15. The resonant filter generates a voltage v 1 The switching circuit 11 is configured to resonate at a fundamental frequency of v 1 The fundamental wave (sine wave) of AC voltage v lThe AC voltage v output from the switching circuit 11 is l is supplied to the load 5 via a passive circuit 20.

[0092] Here, the voltage v shown in Figure 2(b) 1 The waveforms in Fig. 10A and 10B are such that the switching voltages of the first switching element 12 and the second switching element 13 achieve ZVS and ZVDS. However, the switching voltages of the first switching element 12 and the second switching element 13 are determined based on the configuration and setting values ​​of each element provided in the switching circuit 11 and the circuit connected to the switching circuit 11 including the load 5, as well as the length τ of the dead time.

[0093] This is the voltage v as shown in Figure 2(b). 1 The waveform of is a waveform obtained by dividing the input impedance Z (=R+jX, where R is the input resistance and X is the input reactance) of the switching circuit 11 by the reference impedance Z 0 This means that only when the input impedance Z is equal to the reference impedance Z 0 If it is out of range, the voltage v 1 2(b) will be different from that shown in FIG. 2(b), and depending on the input impedance Z, the switching voltages of the first switching element 12 and the second switching element 13 will not be able to achieve not only ZVDS but also ZVS.

[0094] The passive circuit 20 is provided between the switching circuit 11 and the load 5, and has a resistance R l With respect to the variation of 1 and the second control signal Q 2 This is a circuit for converting at least the switching voltage into an impedance that achieves ZVS during the dead time length τ set at

[0095] Specifically, the passive circuit 20 is a resistor R l is the given resistance value R l0If the input impedance Z is the reference impedance Z 0 Here, the reference impedance Z 0 The switching voltages of the first switching element 12 and the second switching element 13 are controlled by the first control signal Q 1 and the second control signal Q 2 The input impedance Z when ZVS and ZVDS are achieved during the dead time period τ set to 100 V is the input impedance Z when the load 5 has a resistance R l is the given resistance value R l0 When the first control signal Q 1 and the second control signal Q 2 The input impedance Z is converted so that the switching voltage is within a range that achieves ZVS during the dead time length τ set to

[0096] In addition, the load inductor 18 shown in FIG. 31(a) that is required for the load 5 is included in the passive circuit 20 in the inverter 2 according to this embodiment. In other words, the passive circuit 20 has an inductance L 0 It is designed to contain ingredients.

[0097] <3. Passive circuit design method> Here, a method for designing the passive circuit 20 capable of converting the above-mentioned input impedance Z will be described.

[0098] <3.1. Reference impedance> First, in the inverter 2, the switching voltages of the first switching element 12 and the second switching element 13 are controlled by the first control signal Q 1 and the second control signal Q 2 The reference impedance Z is the input impedance Z when ZVS and ZVDS are achieved during the dead time τ set 0 This calculation is performed by using the load inductor 18 (with inductance L 031(a) in which the resonant filter (resonant capacitor 16 and resonant inductor 17) is connected in series between the load 5 and the DE class inverter shown in FIG.

[0099] First, the DC voltage V output from the DC voltage source 10 is DC and the voltage v applied across the first capacitor 14 (first switching element 12). 1 and the voltage v applied across the second capacitor 15 (second switching element 13). 2 The following equation (1) holds between

[0100] V DC =v 1 +v 2 (1) Moreover, the current i output from the inverter 2 to the load 5 can be expressed by the following equation (2).

[0101] i=I P sin(ωt)+I Q cos(ωt) (2) On the other hand, when both the first switching element 12 and the second switching element 13 are off, the current i and the current i flowing through the first capacitor 14 are c1 and the current i flowing through the second capacitor 15 c2 According to Kirchhoff's first law, the following equation (3) holds:

[0102] i c2 =i c1 +i (3) If the capacitance of the first capacitor 14 and the second capacitor 15 is C, then equation (3) can be transformed into the following equation (4).

[0103]

number

[0104]

number

[0105]

Number

[0106]

Number

[0107]

Number

[0108]

Number

[0109] v 1 (t)=V 0 +V P sin(ωt)+V Q cos(ωt)+… (10) For this voltage v 1 the AC voltage output to the load 5 is composed only of the fundamental wave of the voltage v 1 passing through the resonance filter composed of the resonance capacitor 16 and the resonance inductor 17. Therefore, considering only the fundamental wave component of the voltage v 1 the fundamental wave Fourier coefficients of the voltage v 1 are represented by the following equations (11) and (12) from equations (9) and (10).

[0110]

number

[0111]

number

[0112]

number

[0113] By solving equations (13) and (14) simultaneously, we obtain the following equation (15).

[0114]

number

[0115]

number

[0116]

number

[0117]

number

[0118] Here, a geodesic line is a line that connects two points in the shortest distance along a curved surface (Riemannian manifold). When viewed on a plane, a geodesic line may be a straight line or a circle (or a part of a circle). In addition, a geodesic line has the characteristic that its tangent is perpendicular to the axis that indicates the reactance component (see Figures 3 and 4).

[0119] On the other hand, by substituting the ZVDS condition into equation (6), the following equation (19) is obtained.

[0120]

number

[0121]

number

[0122]

number

[0123] From equations (18) and (21), the ZVS / ZVDS load point, which is the intersection of the ZVS geodesic line and the ZVDS geodesic line, is expressed by the following equation (22). The ZVS / ZVDS load point expressed by equation (22) is the reference impedance Z 0 It becomes.

[0124]

number

[0125] 3 and 4 are Z-plane diagrams showing the ZVS geodesic, ZVDS geodesic, and ZVS / ZVDS load point for each duty ratio D, where FIG. 3(a) shows the case where the duty ratio D is 0.05, FIG. 3(b) shows the case where the duty ratio D is 0.1, FIG. 3(c) shows the case where the duty ratio D is 0.15, FIG. 3(d) shows the case where the duty ratio D is 0.2, FIG. 3(e) shows the case where the duty ratio D is 0.25, FIG. 3(f) shows the case where the duty ratio D is 0.3, FIG. 4(a) shows the case where the duty ratio D is 0.35, FIG. 4(b) shows the case where the duty ratio D is 0.4, and FIG. 4(c) shows the case where the duty ratio D is 0.45.

[0126] In each Z plane in Figures 3 and 4, the semicircular curve drawn with a solid line indicates the ZVS geodesic line, the straight line drawn with a dashed line indicates the ZVDS geodesic line, and the circle drawn at the intersection of the ZVS geodesic line and the ZVDS geodesic line indicates the ZVS / ZVDS load point.

[0127] When the switching period T is fixed to a predetermined value, as described above, the duty ratio D and the length τ of the dead time (and the magnitude φ of the phase that advances during the time τ) have a one-to-one relationship according to the above formula (A). In other words, if the duty ratio D is determined, the length τ of the dead time is determined, and conversely, if the length τ of the dead time is determined, the duty ratio D is determined.

[0128] For example, if the duty ratio D = 0.05, the length of the dead time is τ = 9T / 20 (φ = 0.9π) (Fig. 3(a)). If the duty ratio D = 0.1, the length of the dead time is τ = 8T / 20 (φ = 0.8π) (Fig. 3(b)). If the duty ratio D = 0.15, the length of the dead time is τ = 7T / 20 (φ = 0.7π) (Fig. 3(c)). If the duty ratio D = 0.2, the length of the dead time is τ = 6T / 20 (φ = 0.6π) (Fig. 3(d)). If the duty ratio D = 0.25, the length of the dead time is τ = 5T / 20 (φ = 0.5π) (Fig. 3(e)). If the duty ratio D = 0.3, the length of the dead time is τ = 4T / 20 (φ = 0.4π) (Fig. 3(f)).

[0129] If the duty ratio D = 0.35, the length of the dead time is τ = 3T / 20 (φ = 0.3π) (Fig. 4(a)). If the duty ratio D = 0.4, the length of the dead time is τ = 2T / 20 (φ = 0.2π) (Fig. 4(b)). If the duty ratio D = 0.45, the length of the dead time is τ = T / 20 (φ = 0.1π) (Fig. 4(c)).

[0130] As shown in FIG. 3 and FIG. 4, the first control signal Q 1 and the second control signal Q 2 If the duty ratio D (i.e., the duration τ of the dead time) is different, the ZVS geodesic curve, the ZVDS geodesic curve, and the ZVS / ZVDS load point will be significantly different.

[0131] That is, in the switching circuit 11, the switching voltages of the first switching element 12 and the second switching element 13 change not only depending on the configuration and setting value of each element provided in the switching circuit 11 and the circuit connected to the switching circuit 11 including the load 5, but also depending on the time length τ of the dead time. Therefore, the switching voltages are determined according to the ZVS geodesic curve where ZVS is achieved, the ZVDS geodesic curve where ZVDS is achieved, and the ZVS / ZVDS load point (reference impedance Z 0 ) also differs depending on the length of dead time τ. Therefore, the passive circuit 20 in the inverter 2 configured as a class DE inverter needs to be designed taking into consideration the length of dead time τ.

[0132] <3.2. Methods of impedance transformation in passive circuits> Next, the concept of impedance conversion in the passive circuit 20 will be described with reference to Fig. 5. Fig. 5(a) shows the first control signal Q 1 and the second control signal Q 2 The ZVS geodesic curve at the dead time length τ set to , and the varying resistance value R of the load 5 l 5(b) is a diagram showing the circle transformation of the Moebius transformation used as impedance transformation by the passive circuit 20 on the Z plane, and FIG. 5(c) is a diagram showing the line transformation of the Moebius transformation on the Z plane.

[0133] As described above, the ZVS geodesic curve is drawn as a part of a circle on the Smith chart and on the Z plane, as shown in FIG. 5(a), FIG. 3 and FIG. 4. On the other hand, the real axis load fluctuation geodesic curve is drawn as a part of a circle on the Smith chart and on the Z plane, as shown in FIG. 5(a), FIG. 3 and FIG. 4. l Since the reactance component is zero, it is drawn as a straight line on the axis representing the resistance component on both the Smith chart and the Z plane (Figure 5(a)).

[0134] As described above, the passive circuit 20 is connected to the load 5 with a resistance R lWith respect to the variation of 1 and the second control signal Q 2 The passive circuit 20 is configured as a circuit that satisfies the impedance parameters obtained by calculating impedance parameters that can perform impedance conversion from a real axis load variation geodesic curve drawn on a Smith chart or a Z-plane to a ZVS geodesic curve. In other words, the resistance value R of the load 5 can be calculated by simply calculating impedance parameters that can perform impedance conversion from a real axis load variation geodesic curve to a ZVS geodesic curve. l It is possible to reliably construct a passive circuit 20 that can convert the input impedance Z to the output of the switching circuit 11 into an input impedance Z that allows the switching voltages of the first switching element 12 and the second switching element 13 to achieve ZVS within the set dead time length τ, in response to fluctuations in the input impedance Z to the output of the switching circuit 11.

[0135] The impedance transformation by the passive circuit 20 is performed by the resistance value R of the load 5 on the real axis load variation geodesic curve. l For the input impedance Z, the first control signal Q 1 and the second control signal Q 2 This is realized by performing a Moebius transformation so that the impedance on the ZVS geodesic curve during the dead time length τ set to

[0136] Here, the Moebius transformation is a projection transformation on a complex projected line, and the load impedance on the real axis load variation geodesic line is expressed as Z l (=R l ), it is converted to input impedance Z using the following formula:

[0137] Z = (A Z l +B) / (C Z l +D) where A·D ≠ B·C Such a Moebius transformation (indicated as MT in Fig. 5(b) and (c)) allows for a circle-to-circle mapping, i.e., a circle-circle transformation, as shown in Fig. 5(b). Also, since a straight line can be regarded as a circle with an infinite radius, the Moebius transformation also allows for a line-to-circle mapping, i.e., a line-circle transformation, as shown in Fig. 5(c). The resistance value R of the load 5 on the real axis load variation geodesic curve in the passive circuit 20 is l The impedance transformation of the input impedance Z from to the ZVS geodesic line is performed using the line-circle transformation of this Möbius transformation.

[0138] Next, a circuit configuration for realizing a Moebius transformation will be described with reference to Fig. 6. Fig. 6(a) is a circuit diagram showing a passive circuit 20 that realizes parallel translation in the vertical axis direction (reactance (X) axis direction) on the Z plane as a circle-circle transformation, Fig. 6(b) is a circuit diagram showing a passive circuit 20 that realizes enlargement / reduction as a circle-circle transformation, and Fig. 6(c) is a circuit diagram showing a passive circuit 20 that realizes rotation as a circle-circle transformation.

[0139] As shown in Figure 6(a), the load impedance Z l When a coil or capacitor with reactance x is connected in series as a passive circuit 20, the load impedance Z l is transformed into an input impedance Z such that

[0140] Z=Z l +jx That is, the circuit shown in FIG. 6(a) has a load impedance Z l This realizes a conversion to input impedance Z by translating the input impedance in the vertical axis direction (reactance (X) axis direction) on the Z plane.

[0141] As shown in FIG. 6(b), the load impedance Z l For the passive circuit 20, if a transformer with a transformation ratio of n is connected in series, the load impedance Z l is transformed into an input impedance Z such that

[0142] Z=n 2 Z l That is, the circuit shown in FIG. 6(b) has a load impedance Z l This realizes conversion to input impedance Z by expanding or contracting.

[0143] Also, as shown in FIG. 6(c), the load impedance Z l For the passive circuit 20, the characteristic impedance Z c When two transmission lines with a phase difference of α at both ends are connected in series, the load impedance Z l is transformed into an input impedance Z such that

[0144] Z=Z c· (Z l +jZ c tanφ) / (Z c +jZ l tanφ) That is, the circuit shown in FIG. 6(c) has a load impedance Z l is rotated to achieve conversion to input impedance Z.

[0145] The passive circuit 20 is constructed so as to realize the impedance transformation from the real axis load variation geodesic to the ZVS geodesic by such a Moebius transformation. l On the other hand, a passive circuit 20 can be constructed that can reliably convert the input impedance Z to the output of the switching circuit 11 to an input impedance Z that achieves ZVS in the first switching element 12 and the second switching element 13.

[0146] In addition, the passive circuit 20 is transformed into a load impedance Z on the real axis load geodesic by combining translation in the vertical axis direction (reactance (X) axis direction) on the Z plane, expansion / contraction, and rotation. lis converted to an input impedance Z on the ZVS geodesic line. This allows the passive circuit 20 to be configured with an inductor and a capacitor. That is, the passive circuit 20 can be configured without using a resistor, so that loss in the passive circuit 20 can be suppressed. Therefore, even if the passive circuit 20 is provided, the inverter 2 can maintain high efficiency.

[0147] <3.3. Derivation of passive circuits> Next, a specific method of deriving the passive circuit 20 will be described with reference to Figs. 7 to 10. Fig. 7(a) is a diagram showing the Z parameter (Z is impedance) of the passive circuit 20. The passive circuit 20 is derived by using the load impedance Z l This is done by calculating the Z parameter of the circuit that converts the input impedance Z on the ZVS geodesic line from the

[0148] The calculation of this Z parameter is done by calculating the load impedance Z at three points from the real axis load change geodesic line. l and the respective load impedances Z l This can be achieved by extracting the desired input impedance Z from the ZVS geodesic curve by performing impedance transformation (Möbius transformation) on the input impedance Z by the passive circuit 20 and solving the equation obtained by the relationship between them.

[0149] Figure 7(b) shows three points Z on the real axis load change geodesic line. la ,Z l0 ,Z lb and three points Z on the ZVS geodesic line that we want to obtain by impedance transformation using the passive circuit 20. a ,Z 0 ,Z b FIG. 7(c) is a diagram showing an example of the correspondence relationship between the two, and FIG. 7(c) is a diagram showing another example of the correspondence relationship.

[0150] In the examples shown in Fig. 7(b) and (c), the resistance value R of the load 5 is set as three points on the real axis load variation geodesic curve. l The first load impedance Z la (=0) and the resistance value R of load 5l is the specified resistance value R determined by the designer. l0 The second load impedance Z l0 (=R l0 ) and the resistance value R of load 5 l The third load impedance Z becomes infinite. lb Extract (=∞).

[0151] The passive circuit 20 then has a first load impedance Z la For the first input impedance Z on the ZVS geodesic a Convert to the second load impedance Z l0 For ZVS geodesic reference impedance Z 0 Convert to the third load impedance Z lb For the second input impedance Z on the ZVS geodesic b shall be converted to

[0152] In this case, the first input impedance Z a , reference impedance Z 0 , the second input impedance Z b is the Z parameter and the first load impedance Z la , the second load impedance Z l0 , the third load impedance Z lb The asymmetric component of the Z parameter, Z 12 ,Z 21 The relationship is also shown in the following formula.

[0153]

number

[0154] By solving these equations, it is possible to calculate the Z parameters of the passive circuit 20. The Z parameters of the passive circuit 20 are given by the following equations (23) to (25).

[0155]

number

[0156] In this example, of the two intersections between the ZVS geodesic line and the reactance axis (resistance value 0), the one with the smaller reactance is the first input impedance Z a The one with the larger reactance is the second input impedance Z b That is, in this case, the passive circuit 20 has a resistance R l The first load impedance Z is the smallest la The first input impedance Z with the smallest reactance a and convert it to the resistance value R of load 5. l The third load impedance Z lb The second input impedance Z b The transformer-type passive circuit 20 is characterized in that, when a constant voltage is input to the inverter 2 from the DC voltage source 10, it converts it into an AC constant voltage, which is an AC voltage with a constant amplitude, and outputs it, and, when a constant current is input to the inverter 2 from the DC current source 10a (see FIG. 15(a)), it converts it into an AC constant current, which is an AC current with a constant amplitude, and outputs it.

[0157] First control signal Q 1 and the second control signal Q 2The first input impedance Z during the dead time length τ set to a and the second input impedance Z b From equation (18), it is expressed by the following equations (26) and (27).

[0158]

number

[0159]

number

[0160]

number

[0161]

number

[0162] Also, the Y parameter of the passive circuit 20, given by (31), is 11 ,Y 12 ,Y 21 ,Y 22 is composed of only susceptances. Here, Fig. 8(b) is a diagram showing a circuit topology that realizes a Y parameter in which all components are composed of only susceptances. In this case, the passive circuit 20 can be realized by a π-type circuit as shown in Fig. 8(b).

[0163] By applying the Z parameter shown in formula (30) to the circuit topology shown in FIG. 8(a) and the Y parameter shown in formula (31) to the circuit topology shown in FIG. 8(b), the transformer-type passive circuit 20 that realizes the impedance conversion shown in FIG. 7(b) can be constructed by the circuit topology shown in FIG. 9. The circuit topology that the transformer-type passive circuit 20 adopts can be determined by the "Z parameter Z". 21 Component reactance X 21 The sign of or the Y parameter Y 21 Component susceptance B 21 " and "the predetermined resistance value R of the load 5 determined in advance by the designer l0 9, based on the relationship between the capacitive reactance (1 / ωC) of the first capacitor 14 (or the second capacitor 15) and the magnitude of the phase advance φ (=ωτ) during the duration τ of the dead time.

[0164] Next, the passive circuit 20 is connected to a first load impedance Z la For the first input impedance Z on the ZVS geodesic a Convert to the second load impedance Z l0For ZVS geodesic reference impedance Z 0 Convert to the third load impedance Z lb For the second input impedance Z on the ZVS geodesic b Consider the case of converting to

[0165] In this example, of the two intersections between the ZVS geodesic line and the reactance axis (resistance value 0), the one with the larger reactance is the first input impedance Z a The one with the smaller reactance is the second input impedance Z b That is, in this case, the passive circuit 20 has a resistance R l The first load impedance Z is the smallest la The first input impedance Z a and convert it to the resistance value R of load 5. l The third load impedance Z lb The second input impedance Z with the smallest reactance b The gyrator-type passive circuit 20 is characterized in that, when a constant voltage is input to the inverter 2 from the DC voltage source 10, it converts it into an AC constant current, which is an AC current with a constant amplitude, and outputs it, and, when a constant current is input to the inverter 2 from the DC current source 10a (see FIG. 15(a)), it converts it into an AC constant voltage, which is an AC voltage with a constant amplitude, and outputs it.

[0166] First control signal Q 1 and the second control signal Q 2 The first input impedance Z during the dead time length τ set to a and the second input impedance Z b This is the opposite of the above equations (26) and (27), resulting in the following equations (32) and (33).

[0167]

number

[0168]

number

[0169] By applying the Z parameter shown in equation (35) to the circuit topology shown in FIG. 8(a) and the Y parameter shown in equation (31) to the circuit topology shown in FIG. 8(b), the gyrator-type passive circuit 20 that realizes the impedance conversion shown in FIG. 7(c) can be constructed by the circuit topology shown in FIG. 10. The circuit topology that the gyrator-type passive circuit 20 adopts can be determined by the "Z parameter Z" in the same manner as the transformer-type passive circuit 20. 21 Component reactance X 21 The sign of or the Y parameter Y 21 Component susceptance B 21 " and "the predetermined resistance value R of the load 5 determined in advance by the designer l0 10, based on the relationship between the capacitive reactance (1 / ωC) of the first capacitor 14 (or the second capacitor 15) and the magnitude of the phase advance φ (=ωτ) during the duration τ of the dead time.

[0170] In the above manner, the passive circuit 20 can be designed and constructed. By providing the passive circuit 20 designed in this manner, the load 5 has a predetermined resistance value R l0 When the input impedance Z to the output of the switching circuit 11 is set to the reference impedance Z 0 Here, the reference impedance Z 0 As described above, the first control signal Q 1 and the second control signal Q 2 is the input impedance Z to the output of the switching circuit 11 when the switching voltages of the first switching element 12 and the second switching element 13 achieve ZVS and ZVDS during the dead time length τ set to 100 V. This allows the load 5 to have a predetermined resistance value R l0 If so, the first control signal Q 1 and the second control signal Q 2 During the dead time length τ set to the above, the switching voltages of the first switching element 12 and the second switching element 13 achieve ZVS and ZVDS, thereby making it possible to suppress the occurrence of losses in the first switching element 12 and the second switching element 13.

[0171] The inverter 2 also operates with the resistance R l Even if the input impedance Z to the output of the switching circuit 11 fluctuates, the first control signal Q 1 and the second control signal Q 2 In the dead time length τ set to 1, the switching voltages of the first switching element 12 and the second switching element 13 can be converted to fall within a range that achieves ZVS. l Even if the first control signal Q 1 and the second control signal Q 2 During the dead time length τ set to 1, the switching voltages of the first switching element 12 and the second switching element 13 achieve at least ZVS, so that the occurrence of loss in the first switching element 12 and the second switching element 13 can be suppressed. lThis makes it possible to provide a DE-class inverter that can perform ideal, highly efficient operation even when the input voltage fluctuates.

[0172] Moreover, as shown in equations (30), (31), (34), and (35), all components of the Z parameter of the passive circuit 20 are represented by reactance, and all components of the Y parameter are represented by susceptance, and the passive circuit 20 is composed of inductors and capacitors as shown in Figures 9 and 10. Therefore, even if the passive circuit 20 is provided in the inverter 2, it is possible to suppress the occurrence of loss in the passive circuit 20.

[0173] <4. Design example and simulation of inverter with passive circuit> Next, the effects of the passive circuit 20 and the inverter 2 are confirmed from the results of a simulation performed on the inverter 2 having the passive circuit 20 designed by the method described above.

[0174] <4.1. Design example 1> First, design example 1 will be described with reference to Fig. 11 and Fig. 12. Fig. 11(a) is a circuit diagram showing an inverter 2 having a passive circuit 20 according to design example 1, and Fig. 11(b) is a diagram showing the values ​​of each parameter of the inverter 2 used in designing the passive circuit 20 and the values ​​of each parameter of the passive circuit 20 obtained by the design. Fig. 12 is a diagram showing the simulation results of the inverter 2.

[0175] The inverter 2 according to the design example 1 is a constant voltage source that outputs a DC voltage V DC From the above, the AC voltage v of constant amplitude is always applied to the load 5. l The passive circuit 20 is a transformer type inverter.

[0176] In the simulation, the first switching element 12 and the second switching element 13 are replaced with ideal switches instead of transistors. lThe simulation was performed for impedances of 25 Ω, 50 Ω, and 100 Ω. These simulation conditions were applied to all of Design Examples 1 to 5 described below.

[0177] As a result of simulating the inverter 2 according to this design example 1, as shown in FIG. 12, the resistance value R l Whatever the resistance value of v, the switching voltage v applied across the first switching element 12 (i.e., the first capacitor 14) 1 However, when the first switching element 12 is turned on (when the dead time ends), it becomes 0 volts. Although not shown explicitly, a simulation result shows that the switching voltage of the second switching element 13 also becomes 0 volts when the second switching element 13 is turned on (when the dead time ends). That is, the inverter 2 has a switching voltage of 0 volts when the resistance value R l Even if the first control signal Q 1 and the second control signal Q 2 During the dead time period τ set to 1, the switching voltage of the switching circuit 11 achieves ZVS. This is because the resistance value R l Even if the input impedance Z of the switching circuit 11 varies, the passive circuit 20 according to the design example 1 controls the input impedance Z of the switching circuit 11 in accordance with the first control signal Q 1 and the second control signal Q 2 This is because the impedance can be transformed so as to be on the ZVS geodesic curve for the time length τ of the dead time set at

[0178] As shown in FIG. 12, the inverter 2 according to the design example 1 has a resistance value R l Regardless of the resistance value of , an AC voltage with the same waveform that does not change in amplitude or phase is generated from a DC voltage source 10 of a constant voltage source, and the AC voltage is voltage v l As a result, the passive circuit 20 outputs a current to the load 5 as a resistance R l It is also possible to realize a function of outputting an AC voltage of a constant amplitude from the inverter 2 regardless of fluctuations in the input voltage.

[0179] <4.2. Design example 2> Next, design example 2 will be described with reference to Fig. 13 and Fig. 14. Fig. 13(a) is a circuit diagram showing an inverter 2 having a passive circuit 20 according to design example 3, and Fig. 13(b) is a diagram showing the values ​​of each parameter of the inverter 2 used in designing the passive circuit 20 and the values ​​of each parameter of the passive circuit 20 obtained by the design. Fig. 14 is a diagram showing the simulation results of the inverter 2.

[0180] The inverter 2 according to the design example 2 is a constant voltage source, and the DC voltage V DC From the above, the AC current i of constant amplitude is always applied to the load 5. l The inverter is a class DE inverter that outputs a gyrator type.

[0181] As a result of simulating the inverter 2 according to this design example 2, as shown in FIG. 14, the resistance value R l Whatever the resistance value of the resistor, the switching voltage v of the first switching element 12 1 However, at the end of the dead time, the switching voltage of the second switching element 13 also becomes 0 volts. l Even if the first control signal Q 1 and the second control signal Q 2 During the time length τ of the dead time set to 1, the switching voltage of the switching circuit 11 achieves ZVS, and the passive circuit 20 according to the design example 2 also reduces the input impedance Z to the output of the switching circuit 11 by the first control signal Q 1 and the second control signal Q 2 It can be seen that the impedance is transformed so as to be on the ZVS geodesic curve for the dead time length τ set as

[0182] As shown in FIG. 14, the inverter 2 according to the design example 2 has a resistance value R lRegardless of the resistance value of i, an AC current with the same waveform that does not change in amplitude or phase is generated from a DC voltage source 10 of a constant voltage source, and the AC current is l As a result, the passive circuit 20 outputs a current to the load 5 as a resistance R l It is also possible to realize a function of outputting an AC current of a constant amplitude from the inverter 2 regardless of fluctuations in the input voltage.

[0183] <4.3. Design example 3> Next, design example 3 will be described with reference to Fig. 15 and Fig. 16. Fig. 15(a) is a circuit diagram showing an inverter 2 having a passive circuit 20 according to design example 3, and Fig. 15(b) is a diagram showing the values ​​of each parameter of the inverter 2 used in designing the passive circuit 20 and the values ​​of each parameter of the passive circuit 20 obtained by the design. Fig. 16 is a diagram showing the simulation results of the inverter 2.

[0184] The inverter 2 according to the design example 3 outputs a current I DC From the above, the AC current i of constant amplitude is always applied to the load 5. l The inverter is a class DE inverter that outputs a transformer type inverter.

[0185] As a result of simulating the inverter 2 according to this design example 3, as shown in FIG. 16, the resistance value R l Whatever the resistance value of the resistor, the switching voltage v of the first switching element 12 1 However, at the end of the dead time, the switching voltage of the second switching element 13 also becomes 0 volts. l Even if the first control signal Q 1 and the second control signal Q 2During the time length τ of the dead time set to 1, the switching voltage of the switching circuit 11 achieves ZVS, and the passive circuit 20 according to the design example 3 also reduces the input impedance Z to the output of the switching circuit 11 by the first control signal Q 1 and the second control signal Q 2 It can be seen that the impedance is transformed so as to be on the ZVS geodesic curve for the dead time length τ set at

[0186] As shown in FIG. 16, the inverter 2 according to the design example 3 has a resistance value R l Regardless of the resistance value of i, an AC current with the same waveform that does not change in amplitude or phase is generated from a DC current source 10a, which is a constant current source, and the AC current is l As a result, the passive circuit 20 outputs a current to the load 5 as a resistance R l It is also possible to realize a function of outputting an AC current of a constant amplitude from the inverter 2 regardless of fluctuations in the input voltage.

[0187] <4.4. Design Example 4> Next, design example 4 will be described with reference to Fig. 17 and Fig. 18. Fig. 17(a) is a circuit diagram showing an inverter 2 having a passive circuit 20 according to design example 4, and Fig. 17(b) is a diagram showing the values ​​of each parameter of the inverter 2 used in designing the passive circuit 20 and the values ​​of each parameter of the passive circuit 20 obtained by the design. Fig. 18 is a diagram showing the simulation results of the inverter 2.

[0188] The inverter 2 according to the design example 4 outputs a current I DC From the above, the AC voltage v of constant amplitude is always applied to the load 5. l and the passive circuit 20 is of the gyrator type.

[0189] As a result of simulating the inverter 2 according to this design example 4, as shown in FIG. 18, the resistance value R l Whatever the resistance value of the resistor, the switching voltage v of the first switching element 121 However, at the end of the dead time, the switching voltage of the second switching element 13 also becomes 0 volts. l Even if the first control signal Q 1 and the second control signal Q 2 During the time length τ of the dead time set to 1, the switching voltage of the switching circuit 11 achieves ZVS, and the passive circuit 20 according to the design example 4 also reduces the input impedance Z to the output of the switching circuit 11 by the first control signal Q 1 and the second control signal Q 2 It can be seen that the impedance is transformed so as to be on the ZVS geodesic curve for the dead time length τ set as

[0190] As shown in FIG. 18, the inverter 2 according to the design example 4 has a resistance value R l Regardless of the resistance value of , an AC voltage with the same waveform that does not change in amplitude or phase is generated from a DC current source 10a of a constant current source, and the AC voltage is converted to a voltage v l As a result, the passive circuit 20 outputs a current to the load 5 as a resistance R l It is also possible to realize a function of outputting an AC voltage of a constant amplitude from the inverter 2 regardless of fluctuations in the input voltage.

[0191] <4.5. Design Example 5> Next, design example 5 will be described with reference to Fig. 19 and Fig. 20. Fig. 19(a) is a circuit diagram showing an inverter 2 having a passive circuit 20 according to design example 5, and Fig. 19(b) is a diagram showing the values ​​of each parameter of the inverter 2 used in designing the passive circuit 20 and the values ​​of each parameter of the passive circuit 20 obtained by the design. Fig. 20 is a diagram showing the simulation results of the inverter 2.

[0192] The inverter 2 according to the design example 5 is a full-bridge type DE class inverter, unlike the inverters 2 described above. As in the design example 1, the inverter 2 is a DC voltage V DC From the above, the AC voltage v of constant amplitude is always applied to the load 5. l However, the switching circuit 11 according to design example 5 is configured by further including a series circuit in which a third capacitor 15a to which a third switching element 13a is connected in parallel and a fourth capacitor 14a to which a fourth switching element 12a is connected in parallel are connected in series, in comparison with the switching circuit 11 of the inverter 2 according to design example 1.

[0193] This series circuit is connected in parallel to DC voltage source 10 together with the series circuit of first capacitor 14 and second capacitor 15 (i.e., the series circuit of first switching element 12 and second switching element 13) such that third capacitor 15a (third switching element 13a) is connected to the negative side of DC voltage source 10 and fourth capacitor 14a (fourth switching element 12a) is connected to the positive side of DC voltage source 10. The capacitances of third capacitor 15a and fourth capacitor 14a are both the same value C as the capacitance of first capacitor 14 and second capacitor 15.

[0194] The connection point between the third switching element 13a and the fourth switching element 12a is the same (has the same potential) as the connection point between the third capacitor 15a and the fourth capacitor 14a, and the potential of this connection point is equal to the voltage v applied across the third capacitor 15a (i.e., the third switching element 13a). 2 This connection point has the same capacitance C r and a resonant capacitor 16a having the same inductance L as the resonant inductor 17. r The resonant inductor 17b having the resonant inductor 17a and the resonant inductor 17b having the resonant inductor 17b are connected in series to a resonant filter, and then the resonant inductor 17b is connected to one end of the load 5 (the lower side in FIG. 19(a)) via a passive circuit 20. That is, the voltage v 2A fundamental wave (sine wave) of is applied.

[0195] On the other hand, the connection point between the first switching element 12 and the second switching element 13 (i.e., the connection point between the first capacitor 14 and the second capacitor 15) is connected to the other end of the load 5 (the upper side in FIG. 19(a)) via a resonant filter formed by a series connection of a resonant capacitor 16 and a resonant inductor 17 and a passive circuit 20, as in the design example 1. That is, the other end of the load 5 is connected to the voltage v applied across the first capacitor 14 (i.e., the first switching element 12) that has passed due to the resonance of this resonant filter. 1 A fundamental wave (sine wave) of is applied.

[0196] Here, a first control signal Q that controls the on / off of the first switching element 12 1 and a second control signal Q for controlling the on / off of the second switching element 13. 2 2(a) are used. A fourth control signal Q 4 is the first control signal Q 1 A third control signal Q is used to control the on / off of the third switching element 13a. 3 is the second control signal Q 2 This uses the same signal as the voltage v 1 is the switching voltage of the first switching element 12 and is equal to the switching voltage of the fourth switching element 12a. 2 is the voltage v 1 This voltage has the opposite polarity to the switching voltage of the third switching element 13a and is equal to the switching voltage of the second switching element 13. Therefore, the load 5 is connected to the voltage v 1 The fundamental wave and voltage v 2 A differential voltage due to the fundamental wave of the inverter 2 according to Design Example 5 is applied as an AC voltage. Since a voltage twice as high as that of the inverter 2 according to Design Example 1 is applied to the load 5, the full-bridge inverter 2 according to Design Example 5 can supply more power than the inverter 2 according to Design Example 1.

[0197] When the inverter 2 is configured as a full-bridge type class DE inverter as described above, the passive circuit 20 can be designed as follows: The passive circuit 20 of the inverter 2 according to design example 5 is of a transformer type.

[0198] In this design, first, a passive circuit 20 is designed based on the inverter 2 according to design example 1 shown in FIG. 11(a), which is obtained by removing the series circuit of the third capacitor 15a with the third switching element 13a connected in parallel and the fourth capacitor 14a with the fourth switching element 12a connected in parallel from the switching circuit 11 of the inverter 2 according to design example 5. In the passive circuit 20 obtained by this design, an element (inductance L in the example shown in FIG. 11(a)) connected in series between the connection point of the first capacitor 14 and the second capacitor 15 and the load 5 is removed. 1 Inductor and inductance L 3 As shown in FIG. 19(a), the inductor (capacitor C) is used as it is as the passive circuit 20 of design example 5, and a similar element is also connected in series between the connection point of the third capacitor 15a and the fourth capacitor 14a and the load 5. On the other hand, in the passive circuit 20 obtained by this design, the element (capacitor C in the example shown in FIG. 11(a)) connected in parallel with the load 5 is 2 If the element is a capacitor, the capacitance is halved, and if the element is an inductor, the inductance is doubled, and the element is connected in parallel to the load 5 as shown in FIG. 19(a).

[0199] As a result of simulating the inverter 2 according to the design example 5 having the passive circuit 20 designed in this way, as shown in FIG. l Regardless of the resistance value of the first switching element 12 and the fourth switching element 12a, the switching voltage v 1 and the switching voltage v of the second switching element 13 and the third switching element 13a. 2 At the end of the dead time, the inverter 2 is at 0 volts. l Even if the first control signal Q1 and the second control signal Q 2 During the time length τ of the dead time set to 1, the switching voltage of the switching circuit 11 achieves ZVS, and the passive circuit 20 according to the design example 5 reduces the input impedance Z to the output of the switching circuit 11 by the first control signal Q 1 and the second control signal Q 2 It can be seen that the impedance is transformed so as to be on the ZVS geodesic curve for the dead time length τ set at

[0200] As shown in FIG. 20, the inverter 2 according to the design example 5 has a resistance value R l Regardless of the resistance value of , an AC voltage with the same waveform that does not change in amplitude or phase is generated from a DC voltage source 10 of a constant voltage source, and the AC voltage is voltage v l As a result, the passive circuit 20 outputs a current to the load 5 as a resistance R l In addition, the inverter 2 can output a constant amplitude AC voltage even when the voltage v l has twice the amplitude compared to the inverter 2 according to design example 1, and it can be seen that even if the passive circuit 20 of the present invention is provided for a full-bridge type DE class inverter, the effects of the full-bridge type can be obtained.

[0201] <5. Rectifier circuit configuration> Next, the configuration of the rectifier circuit 3 used in the contactless power supply system 1 will be described with reference to Fig. 21. Fig. 21 is a circuit diagram of the rectifier circuit 3.

[0202] In order to simplify the explanation of the rectifier circuit 3, the inverter 2 and the coupler 4 shown in FIG. 1, which are provided before the input of the rectifier circuit 3 in the contactless power supply system 1, will be collectively explained as one AC constant voltage source 34. The AC constant voltage source 34 outputs an AC voltage v s The rectifier circuit 3 receives the AC voltage v output from the AC constant voltage source 34. s is entered.

[0203] 1, which are provided before the input of the rectifier circuit 3 in the contactless power supply system 1, may be regarded as a single AC constant current source, depending on the configuration of the inverter 2. The AC constant current source is a constant current source that outputs an AC current whose amplitude is always constant. In this case, the AC current output from the AC constant current source is input to the rectifier circuit 3.

[0204] The rectifier circuit 3 includes a switching circuit 31 whose topology forms a DE-class synchronous rectifier circuit, a passive circuit 32, and a control unit 33. The switching circuit 31 has a circuit configuration in which the input and output of the switching circuit 11 (see FIG. 2(a)) of the inverter 2 are inverted, and each element constituting the switching circuit 31 corresponds to each element constituting the switching circuit 11 (FIG. 2(a)). Each element of the switching circuit 31 is given the same reference numeral as the corresponding element of the switching circuit 11, and description thereof will be omitted.

[0205] An AC constant voltage source 34 is connected to the input side of the switching circuit 31 via a passive circuit 32. One end of the AC constant voltage source 34 is connected to the connection point between the first capacitor 14 and the second capacitor 15 (i.e., the connection point between the first switching element 12 and the second switching element 13) via the passive circuit 32 and a resonant filter formed by the resonant capacitor 16 and the resonant inductor 17. The other end of the AC constant voltage source 34 is connected to the opposite side to the connection point of the first capacitor 14 (i.e., the opposite side to the connection point of the first switching element 12) via the passive circuit 32. As a result, an AC voltage v is applied to the connection point between the first capacitor 14 and the second capacitor 15 (i.e., the connection point between the first switching element 12 and the second switching element 13). s A voltage based on the above (AC voltage via a passive circuit 32 and a resonant filter) is supplied.

[0206] In addition, on the output side of the switching circuit 31, a resistor having a resistance value Rl The load 5 is connected to the first switching element 12 in response to a first control signal Q 1 The second switching element 13 is turned on / off by a second control signal Q 2 On / off is controlled by.

[0207] The switching circuit 31 receives the AC voltage v output from the AC constant voltage source 34. s When the AC voltage v s While synchronizing with the first control signal Q 1 and the second control signal Q 2 By alternately turning on the first switching element 12 and the second switching element 13, a DC voltage or a DC current is generated across the series circuit. The rectifier circuit 3 outputs the DC voltage or the DC current generated across the series circuit to the load 5. 1 and the second control signal Q 2 AC voltage v s The synchronization is performed by the control unit 33. The details of the synchronization will be described later together with the explanation of the control unit 33.

[0208] The smoothing capacitor 19 is provided for the purpose of outputting a stable DC voltage or DC current. The smoothing capacitor 19 enables the rectifier circuit 3 to stabilize the DC voltage or DC current supplied to the load 5. The smoothing capacitor 19 also serves to suppress surge voltages generated by turning on / off the first switching element 12 and the second switching element 13, thereby preventing the first switching element 12 and the second switching element 13 from being destroyed.

[0209] The passive circuit 32 is provided between the AC constant voltage source 34 (in other words, the input terminal of the rectifier circuit 3 to which the AC voltage of the AC constant voltage source 34 is input) and the switching circuit 31, and has a resistance value R l The output impedance ZO to the input of the switching circuit 31 is changed by the first control signal Q 1 and the second control signal Q 2This is a circuit for converting at least the switching voltage into an impedance that achieves ZVS during the dead time length τ set at

[0210] Specifically, the passive circuit 32 is a resistor R l is the given resistance value R l0 When the output impedance ZO is the reference impedance Z 0 Here, the reference impedance Z 0 The switching voltages of the first switching element 12 and the second switching element 13 are controlled by the first control signal Q 1 and the second control signal Q 2 The output impedance ZO is the output impedance when ZVS and ZVDS are achieved during the dead time period τ set to 100 V. The passive circuit 32 also has a resistance R l is the given resistance value R l0 When the first control signal Q 1 and the second control signal Q 2 The output impedance ZO is converted so that the switching voltage is within a range that achieves ZVS during the dead time length τ set to

[0211] Here, the dead time is the first control signal Q 1 and the second control signal Q2 is the first control signal Q 1 and the second control signal Q 2 A first control signal Q 1 and the second control signal Q 2 This is the period during which both signals are OFF (see FIG. 2(b)).

[0212] In the switching circuit 31, similarly to the switching circuit 11 of the inverter 2, the switching voltages of the first switching element 12 and the second switching element 13 change not only depending on the configuration and setting values ​​of each element provided in the switching circuit 31 and the circuit connected to the switching circuit 31 including the load 5, but also depending on the time length τ of the dead time of the first switching element 12 and the second switching element 13. Therefore, the switching voltage is determined based on the ZVS geodesic curve where ZVS is achieved, the ZVDS geodesic curve where ZVDS is achieved, and the ZVS / ZVDS load point (reference impedance Z 0 ) also differs depending on the length of the dead time τ. Therefore, the passive circuit 32 in the rectifier circuit 3 configured as a class DE synchronous rectifier circuit needs to be designed taking into consideration the length of the dead time τ.

[0213] The passive circuit 32 can be designed in a similar manner to the design of the passive circuit 20 of the inverter 2 described in <3. Passive circuit design method>. However, the topology of the passive circuit 32 is obtained by inverting the input side and the output side of the topology determined by Fig. 9 or Fig. 10.

[0214] By providing the passive circuit 32 designed in this manner, the rectifier circuit 3 operates as follows.

[0215] That is, the load 5 has a predetermined resistance R l0 When the output impedance ZO of the switching circuit 31 is changed to the reference impedance Z 0 Here, the reference impedance Z 0 As described above, the switching voltages of the first switching element 12 and the second switching element 13 are controlled by the first control signal Q 1 and the second control signal Q 2 The output impedance ZO of the switching circuit 31 to the input when ZVS and ZVDS are achieved during the dead time period τ set to 100 V. This allows the load 5 to have a predetermined resistance R l0In this case, the switching voltages of the first switching element 12 and the second switching element 13 achieve ZVS and ZVDS, so that the occurrence of loss in the first switching element 12 and the second switching element 13 can be suppressed.

[0216] The rectifier circuit 3 is connected to the load 5 with a resistance value R l Even if the output impedance ZO of the switching circuit 31 varies, the first control signal Q 1 and the second control signal Q 2 In the dead time length τ set to 1, the switching voltages of the first switching element 12 and the second switching element 13 can be converted to fall within a range that achieves ZVS. l Even if the resistance value R of the load 5 fluctuates, the switching voltages of the first switching element 12 and the second switching element 13 at least achieve ZVS, so that the occurrence of loss in the first switching element 12 and the second switching element 13 can be suppressed. l It is possible to provide a class DE synchronous rectifier circuit that can perform ideal operation with high efficiency even when the input current fluctuates.

[0217] Similarly to the passive circuit 20 of the inverter 2, the passive circuit 32 has all its Z parameter components represented by reactance and all its Y parameter components represented by susceptance, and is composed of inductors and capacitors. Therefore, even if the passive circuit 32 is provided in the rectifier circuit 3, it is possible to suppress the occurrence of loss in the passive circuit 32.

[0218] However, in order for the switching voltages of the first switching element 12 and the second switching element 13 to achieve ZVS and for a DC voltage or DC current to be output from the rectifier circuit 3, the AC voltage v s (The AC voltage v output from the AC constant voltage source 34) s In this case, it is necessary to alternately turn on the first switching element 12 and the second switching element 13 while synchronizing with the first switching element 12 and the second switching element 13.

[0219] The control unit 33 controls the AC voltage v s 2(b) controls the first switching element 12 to be on / off at a predetermined duty ratio D corresponding to the time length τ of the dead time while being synchronized with the first control signal Q 1 and a second control signal Q as shown in FIG. 2(b) that controls the on / off of the second switching element 13 at the predetermined duty ratio D. 2 and output it to the switching circuit 31.

[0220] The control unit 33 receives an AC voltage v from an AC constant voltage source 34. s The control unit 33 receives the input AC voltage v s Then, the AC voltage v s Based on the detection result, the AC voltage v s and the first control signal Q 1 The phase difference between the two is the specified phase difference θ, and the AC voltage v s and the second control signal Q 2 The first control signal Q is set to a predetermined phase difference (θ-180°) or (θ+180°). 1 and the second control signal Q 2 Generate.

[0221] The control unit 33 controls the AC voltage v s and the first control signal Q 1 The first control signal Q is set to a predetermined phase difference θ. 1 and generates the first control signal Q 1 The second control signal Q is set to -180° or +180°. 2 The control unit 33 may generate an AC voltage v s and the second control signal Q 2 The second control signal Q is set so that the phase difference between the 2 and generates the second control signal Q 2 The first control signal Q is set to -180° or +180°. 1 In this way, the control unit 33 generates the first control signal Q 1 and the second control signal Q 2As a result, the AC voltage v s and the first control signal Q 1 The phase difference between the two is the specified phase difference θ, and the AC voltage v s and the second control signal Q 2 The first control signal Q is set to a predetermined phase difference (θ-180°) or (θ+180°). 1 and the second control signal Q 2 can be generated.

[0222] When an AC current output from an AC constant current source is input to the rectifier circuit 3, the control unit 33 detects the AC current, and based on the detection result, calculates the AC current and the first control signal Q 1 The phase difference between the two is the specified phase difference θ, and the AC voltage v s and the second control signal Q 2 The first control signal Q is set to a predetermined phase difference (θ-180°) or (θ+180°). 1 and the second control signal Q 2 Generate.

[0223] The control unit 33 controls the AC voltage v s Alternatively, an AC current is detected, and a first control signal Q is generated based on the detection result. 1 and the second control signal Q 2 By generating this, the AC voltage v input to the rectifier circuit 3 s Even if there is a phase shift in the AC current, the AC voltage v s or AC current and the first control signal Q 1 and the second control signal Q 2 The phase difference between them is maintained at a predetermined phase difference θ. This makes it possible to maintain ZVS in the first switching element 12 and the second switching element 13, thereby making it possible to maintain high-efficiency operation in the rectifier circuit 3.

[0224] The predetermined phase difference θ depends on whether the input to the rectifier circuit 3 is an AC constant voltage or an AC constant current, whether the output to the load 5 is a DC constant voltage or a DC constant current, and the off-diagonal component X of the Z parameter of the passive circuit 32 designed by the above method. 21 (=X 12) or the off-diagonal components of the Y parameters B 21 (=B 12 ) is a positive or negative number, as follows:

[0225] (1) When the input to the rectifier circuit 3 is a constant AC voltage and the output to the load 5 is a constant DC voltage, or when the input to the rectifier circuit 3 is a constant AC current and the output to the load 5 is a constant DC current (when the passive circuit 32 is a transformer type), X 21 >0(B 21 >0), θ=180°, X 21 <0(B 21 <0), then θ=0°.

[0226] (2) When the input to the rectifier circuit 3 is a constant AC voltage and the output to the load 5 is a constant DC current, or when the input to the rectifier circuit 3 is a constant AC current and the output to the load 5 is a constant DC voltage (when the passive circuit 32 is a gyrator type), X 21 >0(B 21 <0), θ=-90°, X 21 <0(B 21 >0), then θ = +90°.

[0227] The control unit 33 controls the first control signal Q so that the predetermined phase difference θ is as described above. 1 and the second control signal Q 2 By generating the constant AC voltage v, the switching voltages of the first switching element 12 and the second switching element 13 can achieve ZVS. s Alternatively, when a constant AC current is input, a constant DC voltage or a constant DC current can be output to the load 5 .

[0228] <6. Design example and simulation of a rectifier circuit with a passive circuit> Next, the effects of the passive circuit 32 and the rectifier circuit 3 will be described based on the results of a simulation performed on the rectifier circuit 3 having the passive circuit 32 designed by the method described above.

[0229] <6.1. Design Example 6> First, design example 6 will be described with reference to Fig. 22 and Fig. 23. Fig. 22(a) is a circuit diagram showing a rectifier circuit 3 having a passive circuit 32 according to design example 6, and Fig. 22(b) is a diagram showing the values ​​of each parameter of the rectifier circuit 3 used in designing the passive circuit 32 and the values ​​of each parameter of the passive circuit 32 obtained by the design. Fig. 23 is a diagram showing the results of a simulation of the rectifier circuit 3.

[0230] The rectifier circuit 3 according to the design example 6 is a rectifier circuit that receives an AC voltage v having a constant amplitude from an AC constant voltage source 34. s Therefore, the voltage to the load 5 is always constant DC voltage V RDC and the passive circuit 32 is a transformer type.

[0231] In the simulation, the first switching element 12 and the second switching element 13 were replaced with ideal switches instead of transistors, as in the design examples 1 to 5. In addition, the simulation was performed with a resistance value R l The simulation was performed for impedances of 25 Ω, 50 Ω, and 100 Ω. These simulation conditions were applied to all of Design Examples 6 to 9 described below.

[0232] In design example 6, the passive circuit 32 is designed, and as a result, the off-diagonal components X 21 is a positive value (X 21 The rectifier circuit 3 according to the design example 6 has an AC voltage v s is input and a constant DC voltage is output to the load 5, so in the simulation of design example 6, the predetermined phase difference θ is set to 180°. s The first control signal Q has a phase difference of 180° with 1 The first switching element 12 is turned on / off by the s The second control signal Q has a phase difference of 0° with 2 The second switching element 13 is turned on / off by this.

[0233] As a result of simulating the rectifier circuit 3 according to the design example 6, as shown in FIG. 23, the resistance value R l Whatever the resistance value of v, the switching voltage v applied across the first switching element 12 (i.e., the first capacitor 14) 1 However, when the first switching element 12 is turned on (when the dead time ends), it becomes 0 volts. Although not shown explicitly, a simulation result shows that the switching voltage of the second switching element 13 also becomes 0 volts when the second switching element 13 is turned on (when the dead time ends). That is, the rectifier circuit 3 has a resistance R l Even if the first control signal Q 1 and the second control signal Q 2 During the dead time period τ set to 1, the switching voltage of the switching circuit 31 achieves ZVS. This is because the resistance value R l Even if the output impedance ZO of the switching circuit 31 varies, the passive circuit 32 according to the design example 6 controls the output impedance ZO of the switching circuit 31 to the first control signal Q 1 and the second control signal Q 2 This is because the impedance can be transformed so as to be on the ZVS geodesic curve for the time length τ of the dead time set at

[0234] As shown in FIG. 23, the rectifier circuit 3 according to the design example 6 has a resistance value R l Whatever the resistance value, the AC voltage v s So, the voltage is constant at 100V, V RDC The generated DC constant voltage V RDC It can be seen that the output is sent to load 5.

[0235] From the above, the rectifier circuit 3 having the passive circuit 32 according to the design example 6 uses the passive circuit 32 designed as described above, and further, the AC voltage v s and the first control signal Q 1 The first control signal Q is set so that the predetermined phase difference θ between the 1 and the second control signal Q2 By generating the first control signal Q 1 and the second control signal Q 2 During the dead time length τ set to 1, the switching voltages of the first switching element 12 and the second switching element 13 can achieve ZVS, and the occurrence of losses in the first switching element 12 and the second switching element 13 can be suppressed. In addition, the rectifier circuit 3 uses the passive circuit 32 designed as described above, and by setting the predetermined phase difference θ to 180°, the constant AC voltage v s When the constant voltage V RDC can be output to load 5.

[0236] <6.2. Design Example 7> Next, design example 7 will be described with reference to Fig. 24 and Fig. 25. Fig. 24(a) is a circuit diagram showing a rectifier circuit 3 having a passive circuit 32 according to design example 7, and Fig. 24(b) is a diagram showing the values ​​of each parameter of the rectifier circuit 3 used in designing the passive circuit 32 and the values ​​of each parameter of the passive circuit 32 obtained by the design. Fig. 25 is a diagram showing the results of a simulation of the rectifier circuit 3.

[0237] In the rectifier circuit 3 according to the design example 7, similarly to the design example 6, the amplitude of the AC voltage v input from the AC constant voltage source 34 is constant. s Therefore, the voltage to the load 5 is always constant DC voltage V RDC The passive circuit 32 is a transformer type. However, unlike design example 6, the off-diagonal components X 21 (Off-diagonal components of Y parameters B 21 ) is a negative value (X 21 <0).

[0238] Therefore, in the simulation of design example 7, the predetermined phase difference θ was set to 0°. That is, in this simulation, the AC voltage v s The first control signal Q has a phase difference of 0° with 1 The first switching element 12 is turned on / off by the sThe second control signal Q has a phase difference of 180° with 2 The second switching element 13 is turned on / off by this.

[0239] As a result of simulating the rectifier circuit 3 according to the design example 7, as shown in FIG. 25, the resistance value R l Whatever the resistance value, the switching voltage v 1 It can be seen that the switching voltage of the second switching element 13 becomes 0 volts at the end of the dead time. Although not shown, the result of the simulation shows that the switching voltage of the second switching element 13 also becomes 0 volts at the end of the dead time. l Even if the first control signal Q 1 and the second control signal Q 2 During the dead time period τ set to 1, the switching voltage of the switching circuit 31 achieves ZVS. This is because the resistance value R l Even if the output impedance ZO of the switching circuit 31 varies, the passive circuit 32 according to the design example 7 controls the output impedance ZO of the switching circuit 31 to the first control signal Q 1 and the second control signal Q 2 This is because the impedance can be transformed so as to be on the ZVS geodesic curve for the time length τ of the dead time set at

[0240] As shown in FIG. 25, the rectifier circuit 3 according to the design example 7 has a resistance value R l Whatever the resistance value, the AC voltage v s So, the voltage is constant at 100V, V RDC The generated DC constant voltage V RDC It can be seen that the output is sent to load 5.

[0241] From the above, the rectifier circuit 3 having the passive circuit 32 according to the design example 7 uses the passive circuit 32 designed as described above, and further, the AC voltage v s and the first control signal Q 1 The first control signal Q is set so that the predetermined phase difference θ between the 1 and the second control signal Q 2By generating the first control signal Q 1 and the second control signal Q 2 During the dead time length τ set to 1, the switching voltages of the first switching element 12 and the second switching element 13 can achieve ZVS, and the occurrence of losses in the first switching element 12 and the second switching element 13 can be suppressed. In addition, the rectifier circuit 3 uses the passive circuit 32 designed as described above, and by setting the predetermined phase difference θ to 0°, the constant AC voltage v s When the constant voltage V RDC can be output to load 5.

[0242] <6.3. Design Example 8> Next, design example 8 will be described with reference to Fig. 26 and Fig. 27. Fig. 26(a) is a circuit diagram showing a rectifier circuit 3 having a passive circuit 32 according to design example 8, and Fig. 26(b) is a diagram showing the values ​​of each parameter of the rectifier circuit 3 used in designing the passive circuit 32 and the values ​​of each parameter of the passive circuit 32 obtained by the design. Fig. 27 is a diagram showing the results of a simulation of the rectifier circuit 3.

[0243] The rectifier circuit 3 according to the design example 8 is a rectifier circuit that receives an AC voltage v having a constant amplitude from an AC constant voltage source 34. s Therefore, the current to the load 5 is always constant DC constant current I RDC The passive circuit 32 is a gyrator type. The off-diagonal components X 21 (Off-diagonal components of Y parameters B 21 ) is a positive value (X 21 >0).

[0244] Therefore, in the simulation of design example 8, the predetermined phase difference θ was set to −90°. s The first control signal Q has a phase difference of -90° with 1 The first switching element 12 is turned on / off by the s The second control signal Q has a phase difference of +90° with2 The second switching element 13 is turned on / off by this.

[0245] As a result of simulating the rectifier circuit 3 according to this design example 8, as shown in FIG. 27, the resistance value R l Whatever the resistance value, the switching voltage v 1 It can be seen that the switching voltage of the second switching element 13 becomes 0 volts at the end of the dead time. Although not shown, the result of the simulation shows that the switching voltage of the second switching element 13 also becomes 0 volts at the end of the dead time. l Even if the first control signal Q 1 and the second control signal Q 2 During the dead time period τ set to 1, the switching voltage of the switching circuit 31 achieves ZVS. This is because the resistance value R l Even if the output impedance ZO of the switching circuit 31 varies, the passive circuit 32 according to the design example 8 controls the output impedance ZO of the switching circuit 31 to the input of the first control signal Q 1 and the second control signal Q 2 This is because the impedance can be transformed so as to be on the ZVS geodesic curve for the time length τ of the dead time set at

[0246] As shown in FIG. 27, the rectifier circuit 3 according to the design example 8 has a resistance value R l Whatever the resistance value, the AC voltage v s So, the current is constant at 1A, so I RDC The generated constant DC current I RDC It can be seen that the output is sent to load 5.

[0247] From the above, the rectifier circuit 3 having the passive circuit 32 according to the design example 8 uses the passive circuit 32 designed as described above, and further, the AC voltage v s and the first control signal Q 1 The first control signal Q is set so that the predetermined phase difference θ between 1 and the second control signal Q 2 By generating the first control signal Q 1and the second control signal Q 2 During the dead time length τ set to 1000 V, the switching voltages of the first switching element 12 and the second switching element 13 can achieve ZVS, and the occurrence of losses in the first switching element 12 and the second switching element 13 can be suppressed. In addition, the rectifier circuit 3 uses the passive circuit 32 designed as described above, and by setting the predetermined phase difference θ to -90°, the constant AC voltage v s When the constant current I RDC can be output to load 5.

[0248] <6.4. Design Example 9> Next, design example 9 will be described with reference to Fig. 28 and Fig. 29. Fig. 28(a) is a circuit diagram showing a rectifier circuit 3 having a passive circuit 32 according to design example 9, and Fig. 28(b) is a diagram showing the values ​​of each parameter of the rectifier circuit 3 used in designing the passive circuit 32 and the values ​​of each parameter of the passive circuit 32 obtained by the design. Fig. 29 is a diagram showing the results of a simulation of the rectifier circuit 3.

[0249] In the rectifier circuit 3 according to the design example 9, similarly to the design example 8, the amplitude of the AC voltage v input from the AC constant voltage source 34 is constant. s Therefore, the current to the load 5 is always constant DC constant current I RDC The passive circuit 32 is a gyrator type. However, unlike design example 8, the off-diagonal components X 21 (Off-diagonal components of Y parameters B 21 ) is a negative value (X 21 <0).

[0250] Therefore, in the simulation of design example 9, the predetermined phase difference θ was set to +90°. That is, in this simulation, the AC voltage v s The first control signal Q has a phase difference of +90° with 1 The first switching element 12 is turned on / off by the s The second control signal Q has a phase difference of -90° with 2The second switching element 13 is turned on / off by this.

[0251] As a result of simulating the rectifier circuit 3 according to this design example 9, as shown in FIG. 29, the resistance value R l Whatever the resistance value, the switching voltage v 1 It can be seen that the switching voltage of the second switching element 13 becomes 0 volts at the end of the dead time. Although not shown, the result of the simulation shows that the switching voltage of the second switching element 13 also becomes 0 volts at the end of the dead time. l Even if the first control signal Q 1 and the second control signal Q 2 During the dead time period τ set to 1, the switching voltage of the switching circuit 31 achieves ZVS. This is because the resistance value R l Even if the output impedance ZO of the switching circuit 31 varies, the passive circuit 32 according to the design example 9 controls the output impedance ZO of the switching circuit 31 in accordance with the first control signal Q 1 and the second control signal Q 2 This is because the impedance can be transformed so as to be on the ZVS geodesic curve for the time length τ of the dead time set at

[0252] As shown in FIG. 29, the rectifier circuit 3 according to the design example 9 has a resistance value R l Whatever the resistance value, the AC voltage v s So, the current is constant at 1A, so I RDC The generated constant DC current I RDC It can be seen that the output is sent to load 5.

[0253] From the above, the rectifier circuit 3 having the passive circuit 32 according to the design example 9 uses the passive circuit 32 designed as described above, and further, the AC voltage v s and the first control signal Q 1 The first control signal Q is set so that the predetermined phase difference θ between the 1 and the second control signal Q 2 By generating the first control signal Q 1 and the second control signal Q2 During the dead time length τ set to 1000 V, the switching voltages of the first switching element 12 and the second switching element 13 can achieve ZVS, and the occurrence of losses in the first switching element 12 and the second switching element 13 can be suppressed. In addition, the rectifier circuit 3 uses the passive circuit 32 designed as described above, and by setting the predetermined phase difference θ to +90°, the constant AC voltage v s When the constant current I RDC can be output to load 5.

[0254] <6.5. Other design examples> Although not shown in the figure, for the rectifier circuit 3 configured as a DE-class synchronous rectifier circuit to which an AC current with a constant amplitude is input from an AC constant current source, a passive circuit 32 was designed under the following conditions, and a simulation was performed for the rectifier circuit 3 having the passive circuit 32.

[0255] (1) The current to the load 5 is always constant DC constant current I RDC and outputs the off-diagonal components of the Z parameters X 21 (Off-diagonal components of Y parameters B 21 ) is a positive value (X 21 >0). In this case, the simulation was performed with the predetermined phase difference θ set to 180°.

[0256] (2) The current to the load 5 is always constant DC constant current I RDC and outputs the off-diagonal components of the Z parameters X 21 (Off-diagonal components of Y parameters B 21 ) is a negative value (X 21 <0). In this case, the simulation was performed with the predetermined phase difference θ set to 0°.

[0257] (3) A constant DC voltage V across the load 5 RDC and outputs the off-diagonal components of the Z parameters X 21 (Off-diagonal components of Y parameters B 21 ) is a positive value (X 21>0). In this case, the simulation was performed with the predetermined phase difference θ set to -90°.

[0258] (4) A constant DC voltage V across the load 5 RDC and outputs the off-diagonal components of the Z parameters X 21 (Off-diagonal components of Y parameters B 21 ) is a negative value (X 21 <0). In this case, the simulation was performed with the predetermined phase difference θ set to +90°.

[0259] As a result of the simulation, in either case of the rectifier circuit 3, the first control signal Q 1 and the second control signal Q 2 It was confirmed that the switching voltages of the first switching element 12 and the second switching element 13 can achieve ZVS and the occurrence of losses in the first switching element 12 and the second switching element 13 can be suppressed when the dead time length τ is set to 100 Hz. In addition, it was confirmed that, in any case of the rectifier circuit 3, when a constant AC voltage is input, the constant DC voltage V RDC Or constant current DC constant current I RDC It was confirmed that it was possible to output to a load of 5.

[0260] <7. Summary> As described above, the contactless power supply system 1 according to this embodiment has an inverter 2 on the power supply side and a rectifier circuit 3 on the power receiving side, with the inverter 2 and the rectifier circuit 3 being coupled together by a coupler 4.

[0261] The inverter 2 is configured as a DE class inverter, and the switching circuit 11 thereof has a first switching element 12 and a second switching element 13. The inverter 2 is configured as a DE class inverter, and the switching circuit 11 thereof has a first switching element 12 and a second switching element 13. l0 However, when the resistance value R of the load 5 is lIf this fluctuates, the switching voltages of the first switching element 12 and the second switching element 13 will not be able to achieve ZVS and ZVDS.

[0262] Here, the inverter 2, which is a DE class inverter, receives a first control signal Q 1 and a second control signal Q for turning on the second switching element 13. 2 Between the on signal and the first control signal Q 1 and the second control signal Q 2 A dead time is provided in which both are OFF signals to turn off both the first switching element 12 and the second switching element 13. The switching voltages of the first switching element 12 and the second switching element 13 are determined based on the time length τ of this dead time.

[0263] In the inverter 2, a passive circuit 20 is provided between the switching circuit 11 and the load 5, and the passive circuit 20 converts the input impedance Z to the output of the switching circuit 11. Specifically, when the load 5 has a predetermined resistance value R l0 When the input impedance Z to the output of the switching circuit 11 is set to the reference impedance Z 0 It is converted to the reference impedance Z 0 The switching voltages of the first switching element 12 and the second switching element 13 are controlled by the first control signal Q 1 and the second control signal Q 2 is the input impedance Z to the output of the switching circuit 11 when ZVS and ZVDS are achieved during the dead time period τ set to the value of 1. Also, when the load 5 has a predetermined resistance value R l0 Even if the input impedance Z to the output of the switching circuit 11 varies from the first control signal Q 1 and the second control signal Q 2 During the dead time length τ set to the above, the switching voltages of the first switching element 12 and the second switching element 13 are converted by the passive circuit 20 so as to be within a range for achieving ZVS.

[0264] As described above, the switching voltage is determined based on the length τ of the dead time. By designing the passive circuit 20 as described above, the passive circuit 20 can determine the switching voltage when the load 5 has a predetermined resistance value R while taking into account the length τ of the dead time. l0 If so, the input impedance Z to the output of the switching circuit 11 is the reference impedance Z 0 and the load 5 has a given resistance R l0 The input impedance Z to the output of the switching circuit 11 is converted so that the switching voltages of the first switching element 12 and the second switching element 13 are within a range that achieves ZVS even if the input impedance Z varies from .

[0265] This causes the load 5 to have a given resistance R l0 If so, the first control signal Q 1 and the second control signal Q 2 During the dead time length τ set to 1, the switching voltages of the first switching element 12 and the second switching element 13 achieve ZVS and ZVDS, so that it is possible to suppress the occurrence of losses in the first switching element 12 and the second switching element 13. l0 Even if the switching voltage of the first switching element 12 and the second switching element 13 fluctuates from the first control signal Q 1 and the second control signal Q 2 Since ZVS is achieved at least during the dead time length τ set to the value τ, the occurrence of losses in the first switching element 12 and the second switching element 13 can be prevented by the load 5 having a predetermined resistance value R l0 can be suppressed in the same way as if

[0266] Therefore, the resistance value R of load 5 l This makes it possible to provide a DE-class inverter that can perform ideal, highly efficient operation even when the input voltage fluctuates.

[0267] The rectifier circuit 3 is formed of a DE-class synchronous rectifier circuit, and its circuit configuration is obtained by inverting the input and output of the circuit configuration of the inverter 2. That is, the switching circuit 31 of the rectifier circuit 3 has a first switching element 12 and a second switching element 13, similar to the switching circuit 11 of the inverter 2, and the switching operations of the first switching element 12 and the second switching element 13 in the rectifier circuit 3 are similar to those of the switching circuit 11 of the inverter 2.

[0268] The rectifier circuit 3 has a passive circuit 32 between the input terminal of the rectifier circuit 3 and the switching circuit 31, and the passive circuit 32 converts the output impedance ZO to the input of the switching circuit 31. Specifically, when the load 5 has a predetermined resistance R l0 When the output impedance ZO of the switching circuit 31 is equal to the reference impedance Z 0 It is converted to the reference impedance Z 0 is the first control signal Q 1 and the second control signal Q 2 is the output impedance ZO to the input of the switching circuit 11 when the switching voltages of the first switching element 12 and the second switching element 13 achieve ZVS and ZVDS during the dead time length τ set to 100 V. Also, l0 Even if the output impedance ZO of the switching circuit 11 varies from the first control signal Q 1 and the second control signal Q 2 During the dead time length τ set to the above, the switching voltages of the first switching element 12 and the second switching element 13 are converted by the passive circuit 32 so as to be within a range for achieving ZVS.

[0269] In the rectifier circuit 3, the switching voltage is also determined based on the length τ of the dead time. However, by designing the passive circuit 32 as described above, the passive circuit 32 can be designed to operate in a manner such that the load 5 has a predetermined resistance value R while taking into account the length τ of the dead time. l0Then, the output impedance ZO to the input of the switching circuit 11 is the reference impedance Z 0 and the load 5 has a given resistance R l0 The output impedance ZO to the input of the switching circuit 11 is converted so that the switching voltages of the first switching element 12 and the second switching element 13 are within a range that achieves ZVS even if the output impedance ZO fluctuates from .

[0270] This causes the load 5 to have a given resistance R l0 In this case, the switching voltages of the first switching element 12 and the second switching element 13 are controlled by the first control signal Q 1 and the second control signal Q 2 Since ZVS and ZVDS are achieved during the dead time length τ set to the value 0, it is possible to suppress the occurrence of losses in the first switching element 12 and the second switching element 13. l0 Even if the switching voltage of the first switching element 12 and the second switching element 13 fluctuates from the first control signal Q 1 and the second control signal Q 2 Since ZVS is achieved at least during the dead time length τ set to the value τ, the occurrence of losses in the first switching element 12 and the second switching element 13 can be prevented by the load 5 having a predetermined resistance value R l0 can be suppressed in the same manner as if

[0271] Therefore, the resistance value R of load 5 l It is possible to provide a class DE synchronous rectification circuit that can perform ideal operation with high efficiency even when the input voltage fluctuates.

[0272] The contactless power supply system 1 is configured with such an inverter 2 and rectifier circuit 3, and is therefore capable of supplying power to the load 5 in a contactless manner with high efficiency.

[0273] <8. Variations> Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and it can be easily assumed that various improvements and modifications are possible within the scope of the present invention. For example, each embodiment including the modified examples described below may be modified by adding a part or a plurality of parts of the configuration of another embodiment to the embodiment, or by replacing a part or a plurality of parts of the configuration of the embodiment. In addition, the numerical values ​​given in the above embodiments are merely examples, and other numerical values ​​can be naturally adopted.

[0274] In the above embodiment, in the rectifier circuit 3, the control unit 33 controls the AC voltage v input to the rectifier circuit 3 from the AC constant voltage source 34. s Based on the detection result, the AC voltage v s and the first control signal Q 1 The phase difference between the two is the specified phase difference θ, and the AC voltage v s and the second control signal Q 2 The first control signal Q is set to a predetermined phase difference (θ-180°) or (θ+180°). 1 and the second control signal Q 2 We have explained the case where an AC voltage v s and the first control signal Q 1 and the second control signal Q 2 If the phase difference between the first control signal Q 1 and the second control signal Q 2 The method for generating the may be any method.

[0275] FIG. 30 shows the first control signal Q 1 and the second control signal Q 2 FIG. 3 is a diagram for explaining a modified example of a method for generating an AC voltage v input to a rectifier circuit 3 from an AC constant voltage source 34. s Alternatively, the AC current is detected, and the first control signal Q 1 and the second control signal Q 2 Then, the control unit 33 generates a constant DC voltage V RDCOr DC constant current I RDC The first control signal Q 1 and the second control signal Q 2 By this feedback control, the control unit 33 controls the phase of the AC voltage v s or AC current and the first control signal Q 1 The phase difference between the AC voltage v and the s or AC current and second control signal Q 2 The phase difference between the AC voltage v input to the rectifier circuit 3 can be set to a predetermined phase difference (θ-180°) or (θ+180°). s Even if the constant voltage characteristic of the rectifier circuit 3 or the constant current characteristic of the AC current characteristic is lost and there is a fluctuation in amplitude, the magnitude of the DC voltage or DC current output from the rectifier circuit 3 can be kept constant by feedback control.

[0276] In another modified example, the control unit 33 controls the AC voltage v input to the rectifier circuit 3 from the AC constant voltage source 34. s Alternatively, the AC current is detected, and the first control signal Q 1 and the second control signal Q 2 This modification is the same as the previous modification in that it generates the first control signal Q 1 and the second control signal Q 2 The method of feedback control of the phase of the AC voltage v input to the rectifier circuit 3 is different from that of the previous modification. s and the DC constant voltage V output from the rectifier circuit 3 RDC The ratio of the AC voltage v input to the rectifier circuit 3 s and the DC constant current I output from the rectifier circuit 3 RDC The ratio of the AC current input to the rectifier circuit 3 to the DC constant current I RDC The ratio of the AC current input to the rectifier circuit 3 to the DC constant voltage V RDC The first control signal Q 1 and the second control signal Q 2 By this feedback control, the control unit 33 also controls the phase of the AC voltage vs or AC current and the first control signal Q 1 The phase difference between the AC voltage v and the s or AC current and second control signal Q 2 The phase difference between the AC voltage v input to the rectifier circuit 3 can be set to a predetermined phase difference (θ-180°) or (θ+180°). s Even if the constant voltage characteristic of the DC constant voltage V or the constant current characteristic of the AC current is lost and there is a fluctuation in the amplitude, the control unit 33 adjusts the DC constant voltage V RDC Or DC constant current I RDC While varying the magnitude of the bias current, it is possible to maintain ZVS in the first switching element 12 and the second switching element 13. Therefore, it is possible to maintain high efficiency operation in the rectifier circuit 3.

[0277] In the above embodiment, the contactless power supply system 1 has been described as having the inverter 2 on the power supply side and the rectifier circuit 3 on the power receiving side, and these are coupled by the coupler 4. In contrast, the contactless power supply system 1 may have the inverter 2 on the power supply side, and a rectifier circuit or other circuit different from the rectifier circuit 3 on the power receiving side, and these may be coupled by the coupler 4. In this case, the contactless power supply system 1 can enjoy at least the effect of the inverter 2. Furthermore, the contactless power supply system 1 may have an inverter different from the inverter 2 on the power supply side, and a rectifier circuit 3 on the power receiving side, and these may be coupled by the coupler 4. In this case, the contactless power supply system 1 can enjoy at least the effect of the rectifier circuit 3.

[0278] In the above embodiment, the inverter 2 is described as being used in the wireless power supply system 1, but this is not limited to this, and the inverter 2 can be used in an apparatus or system that requires a circuit for generating and outputting an AC voltage or AC current from a DC voltage or DC current.

[0279] In the above embodiment, the rectifier circuit 3 is described as being used in the wireless power supply system 1, but this is not limited to the above, and the rectifier circuit 3 can be used in an apparatus or system that requires a circuit for generating and outputting a DC voltage or DC current from an AC voltage or AC current. [Explanation of symbols]

[0280] 1. Wireless power supply system 2 Inverter 3 Rectifier circuit 4 Combiner 5. Load 10 DC voltage source 10a DC current source 11 Switching Circuits 12 First switching element 13 Second switching element 14 First Capacitor 15 Second Capacitor 20 Passive Circuits 31 Switching Circuits 32 Passive Circuits 33 Control Unit 34 AC constant voltage source D Duty ratio Q 1 First Control Signal Q 2 Second Control Signal R l Resistance Value R l0 Predetermined resistance value T switching period Z Input impedance Z 0 Reference Impedance Z O Output Impedance τ Dead time duration

Claims

1. An inverter that generates an AC voltage or an AC current to be supplied to a load from a DC voltage or a DC current, a switching circuit including a series circuit in which a first capacitor having a first switching element connected in parallel and a second capacitor having a second switching element connected in parallel are connected in series, the switching circuit being configured to output an AC voltage or an AC current based on a voltage or a current generated at a connection point between the first capacitor and the second capacitor by alternately turning on the first switching element and the second switching element in a state in which the series circuit is connected to the DC voltage or the DC current; a passive circuit provided between the switching circuit and the load for transforming an input impedance to an output of the switching circuit; The switching circuit includes: a first control signal composed of an on signal and an off signal for controlling on / off of the first switching element at a predetermined duty ratio, and a second control signal composed of an on signal and an off signal for controlling on / off of the second switching element at the predetermined duty ratio are input; the on signal of the first control signal and the on signal of the second control signal are generated alternately in time, and a dead time is provided between the on signal of the first control signal and the on signal of the second control signal, during which both the first control signal and the second control signal are the off signals; The passive circuit includes: The input impedance when the switching voltages of the first switching element and the second switching element, which are determined based on the configuration and setting values ​​of each element provided in the switching circuit and a circuit connected to the switching circuit including the load and the time length of the dead time, achieve zero voltage switching and zero voltage differential switching during the time length of the dead time, is set as a reference impedance, converting the input impedance to the reference impedance when the load has a predetermined resistance value; An inverter configured to convert the input impedance so that, when the resistance value of the load varies from the predetermined resistance value, the switching voltage is within a range that achieves the zero voltage switching during the dead time.

2. 2. The inverter according to claim 1, wherein the passive circuit is configured as a circuit that satisfies an impedance parameter that can perform impedance conversion from a real axis load variation geodesic curve that depicts a variation in resistance value of the load on a Smith chart to a zero voltage switching geodesic curve that depicts the input impedance that achieves the zero voltage switching during the time length of the dead time on the Smith chart.

3. 3. The inverter according to claim 2, wherein the impedance parameters of the passive circuit are calculated such that an impedance transformation from the real axis load variation geodesic to the zero voltage switching geodesic is performed by a Moebius transformation using at least one of enlargement / reduction, rotation, and translation in the vertical axis direction on an impedance plane whose vertical axis is represented by reactance components and whose horizontal axis is represented by resistance components.

4. 2. The inverter according to claim 1, wherein the passive circuit comprises an inductor and a capacitor.

5. A rectifier circuit that rectifies an AC voltage or an AC current and outputs a DC voltage or a DC current to a load, a switching circuit including a series circuit in which a first capacitor to which a first switching element is connected in parallel and a second capacitor to which a second switching element is connected in parallel are connected in series, and which outputs the DC voltage or the DC current by alternately turning on the first switching element and the second switching element under predetermined conditions in a state in which a voltage or current based on the AC voltage or the AC current is supplied to a connection point between the first capacitor and the second capacitor; a passive circuit provided between an input terminal of the rectifier circuit to which the AC voltage or the AC current is input and the switching circuit, for converting an output impedance to an input of the switching circuit; a control unit that generates a first control signal composed of an on signal and an off signal that controls on / off of the first switching element at a predetermined duty ratio, and a second control signal composed of an on signal and an off signal that controls on / off of the second switching element at a duty ratio equal to the predetermined duty ratio, and outputs the generated control signal to the switching circuit; The control unit is generating the first control signal and the second control signal such that the on signal of the first control signal and the on signal of the second control signal are generated alternately in time, a dead time is provided between the on signal of the first control signal and the on signal of the second control signal, the first control signal and the second control signal both become off signals, and a predetermined phase difference exists between the first control signal and the second control signal and the AC voltage or the AC current input to the rectifier circuit; The passive circuit includes: the output impedance when the switching voltages of the first switching element and the second switching element, which are determined based on the configuration and setting values ​​of each element provided in the switching circuit and a circuit connected to the switching circuit including the load, and the length of the dead time, achieve zero voltage switching and zero voltage differential switching during the length of the dead time, is set as a reference impedance; converting the output impedance to the reference impedance when the load has a predetermined resistance value; A rectifier circuit characterized in that it is configured to convert the output impedance so that, when the resistance value of the load varies from the predetermined resistance value, the switching voltage is within a range that achieves the zero voltage switching during the dead time length.

6. 6. The rectifier circuit according to claim 5, wherein the predetermined phase difference is determined by whether the input to the rectifier circuit is a constant voltage or a constant current, whether the output to the load is a constant voltage or a constant current, and whether the off-diagonal components of the Z parameters or the off-diagonal components of the Y parameters representing the passive circuit are positive or negative numbers.

7. The rectifier circuit according to claim 5, characterized in that the control unit detects the AC voltage or the AC current input to the rectifier circuit, and generates the first control signal and the second control signal based on the detection result so that a phase difference between the first control signal and the second control signal and the AC voltage or the AC current input to the rectifier circuit becomes the predetermined phase difference.

8. The rectifier circuit according to claim 5, characterized in that the control unit detects the AC voltage or the AC current input to the rectifier circuit to generate the first control signal and the second control signal, and adjusts the phases of the first control signal and the second control signal so that the DC voltage or the DC current becomes a predetermined target value.

9. 6. The rectifier circuit according to claim 5, wherein the control unit detects the AC voltage or the AC current input to the rectifier circuit to generate the first control signal and the second control signal, and adjusts the phases of the first control signal and the second control signal so that a ratio between the AC voltage and the DC voltage, a ratio between the AC voltage and the DC current, a ratio between the AC current and the DC current, or a ratio between the AC current and the DC voltage becomes a predetermined target value.

10. 5. A contactless power supply system comprising an inverter according to claim 1 on a power supply side, the inverter being coupled to a rectifier circuit via a coupler.

11. 10. A contactless power supply system comprising a rectifier circuit according to claim 5 on a power receiving side, the rectifier circuit being coupled to an inverter via a coupler.

12. 10. A contactless power supply system comprising an inverter according to claim 1 on a power supply side, a rectifier circuit according to claim 5 on a power receiving side, and the inverter and the rectifier circuit are coupled together by a coupler.

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