Inverter Circuit and Electric Field Coupling Type Contactless Power Supply Device

Abstract

To provide a circuit technique capable of outputting high-frequency AC power of a plurality of phases with a simple circuit configuration.SOLUTION: An inverter circuit (1) comprises: a primary side circuit (2) comprising a plurality of self-excited oscillation circuits (10) connected to a DC power supply (BT); and a secondary side circuit (3) for outputting AC power of a plurality of phases according to the oscillation of the plurality of self-excited oscillation circuits. Each of the self-excited oscillation circuits (10) comprises power transmission coils (N11, N12), a resonance capacitor (C11), a pair of switching elements (Q11, Q12), a drive coil (ND), and a phase shift filter (F20). According to each of control electrodes of the pair of switching elements (Q11, Q12), a voltage thereof is applied from the drive coil (ND) of another self-excited oscillation circuit (10). A phase of the voltage applied to each of the control electrodes of the pair of switching elements (Q11, Q12) is shifted with a phase shift amount corresponding to the number of phases of output power for each of the self-excited oscillation circuits (10), along with action of at least the phase shift filter (F20).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a circuit technology for outputting self-excited oscillation type multi-phase alternating current power.

Background Art

[0002] When obtaining three-phase alternating current output for motor control or the like, a method using rotation of a coil or a magnet or a separately excited circuit is generally used. Patent Document 1 below discloses a motor drive control device including a converter that voltage-converts an output voltage from a DC power source and supplies it to an inverter, and a control unit that controls a supply current to a motor by PWM-controlling the inverter. Since this method performs PWM control of the inverter by the control unit, it can be regarded as a method using a separately excited circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the above-described general methods for obtaining multi-phase alternating current output have problems. For example, a method using rotation of a coil or a magnet has a problem that it can only output low-frequency alternating current depending on the commercial power frequency of 50 Hz (hertz) or 60 Hz, and a method using a separately excited circuit has a problem that the number of circuit components increases and the control becomes complicated. The present invention has been made in view of such circumstances, and provides a circuit technology capable of outputting high-frequency multi-phase alternating current power with a simple circuit configuration.

Means for Solving the Problems

[0005] According to the present invention, there is provided an inverter circuit including a primary side circuit having a plurality of self-excited oscillation circuits connected to a DC power supply, and a secondary side circuit that outputs a plurality of phase AC powers having different phases from each other in response to the oscillation of the plurality of self-excited oscillation circuits. Each of the plurality of self-excited oscillation circuits includes a power transmission coil, a resonance capacitor that forms a resonance circuit together with the power transmission coil, a switching element pair connected to the power transmission coil, and is configured to generate an induced electromotive force having a frequency corresponding to the resonance frequency of the resonance circuit, and a drive coil that applies a voltage to each control electrode of the switching element pair of another one of the self-excited oscillation circuits in response to the induced electromotive force, and a phase shift filter. The secondary side circuit includes a plurality of power reception coils that are magnetically coupled to the power transmission coils of the plurality of self-excited oscillation circuits, respectively. Each control electrode of the switching element pair is applied with a voltage from the drive coil of another one of the self-excited oscillation circuits, and the phase of the voltage applied to each control electrode of the switching element pair of the other one of the self-excited oscillation circuits is shifted by a phase shift amount corresponding to the number of phases of the output power for each self-excited oscillation circuit at least due to the action of the phase shift filter.

Effect of the Invention

[0006] According to the present invention, it is possible to provide a circuit technology capable of outputting high-frequency multi-phase AC power with a simple circuit configuration.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0008] Hereinafter, examples of preferred embodiments of the present invention (hereinafter referred to as the present embodiment) will be described. Note that each of the embodiments described below is an example, and the present invention is not limited to the configurations of the following embodiments.

[0009] [First Embodiment] FIG. 1 is a circuit diagram of the inverter circuit 1 in the first embodiment. The inverter circuit 1 includes a primary circuit 2 having a battery device BT, and a secondary circuit 3 that outputs a plurality of phases of AC power with different phases from each other by magnetic coupling with the primary circuit 2. In the first embodiment, the battery device BT is a battery device that supplies DC power, and an example in which three-phase AC power is output from the secondary circuit 3 is shown.

[0010] [Primary Circuit] The primary circuit 2 further includes three self-excited oscillation circuits 10(1), 10(2), and 10(3) connected in parallel to the battery device BT. In the example of FIG. 1, each of the self-excited oscillation circuits 10(1), 10(2), and 10(3) has the same configuration and constitutes a collector resonance type self-excited oscillation circuit, respectively. Specifically, the self-excited oscillation circuit 10(1) includes a power transmission coil N11(1) and N12(1), a resonance capacitor C11(1), transistors Q11(1) and Q12(1) as a switching element pair, a bias circuit B10(1), a drive coil ND(1), a phase shift filter F20(1), etc. The self-excited oscillation circuit 10(2) includes a power transmission coil N11(2) and N12(2), a resonance capacitor C11(2), transistors Q11(2) and Q12(2) as a switching element pair, a bias circuit B10(2), a drive coil ND(2), a phase shift filter F20(2), etc. The self-excited oscillation circuit 10(3) includes a power transmission coil N11(3) and N12(3), a resonance capacitor C11(3), transistors Q11(3) and Q12(3) as a switching element pair, a bias circuit B10(3), a drive coil ND(3), a phase shift filter F20(3), etc. In the following description, unless it is necessary to distinguish each one, the reference numerals without parentheses are used to indicate any one of the self-excited oscillation circuits or its components. Also, the self-excited oscillation circuit 10 may be abbreviated as circuit 10.

[0011] The power transmission coil N11 and the power transmission coil N12 are connected in series via an intermediate tap, and the intermediate tap is connected to the plus terminal of the battery device BT via the input coil L11. Hereinafter, when one end of the power transmission coil N11 or one end of the power transmission coil N12 is described, it means one end on the side opposite to the intermediate tap side of the power transmission coils N11 and N12. One end of the power transmission coil N11 is connected to the minus terminal of the battery device BT via the transistor Q11, and one end of the power transmission coil N12 is connected to the minus terminal of the battery device BT via the transistor Q12.

[0012] The resonance capacitor C11 is connected in parallel to the power transmission coils N11 and N12, and together with the power transmission coils N11 and N12, constitutes a resonance circuit. Transistors Q11 and Q12 are FETs (Field Effect Transistors) and can be referred to as a switching element pair. The drain of transistor Q11 is connected to one end of power transmission coil N11, and the drain of transistor Q12 is connected to one end of power transmission coil N12. The sources of transistors Q11 and Q12 are connected to the negative terminal of battery device BT. Also, the gates of transistors Q11 and Q12 are connected to bias circuit B10.

[0013] Bias circuit B10 is composed of resistor elements R11, R12, R13, and R14. Bias circuit B10 is connected in parallel to battery device BT and applies a bias voltage to each gate of transistors Q11 and Q12.

[0014] Drive coil ND is provided so as to be magnetically coupled to power transmission coils N11 and N12. For example, drive coil ND is formed as an auxiliary winding on the primary side of the same transformer as power transmission coils N11 and N12. In this embodiment, drive coil ND is magnetically coupled to power transmission coils N11 and N12 such that their polarities are opposite, and a back electromotive force of the oscillation frequency generated in power transmission coils N11 and N12 is generated in drive coil ND. However, the polarity of drive coil ND is not limited to the example in FIG. 1 as will be described later. Also, the drive coil ND is provided so that a voltage can be applied to each control electrode of a switching element pair in another circuit 10 according to its electromotive force. Specifically, one end of the drive coil ND(1) is connected to the gate (control electrode) of the transistor Q11(3) in the circuit 10(3), and the other end of the drive coil ND(1) is connected to the gate (control electrode) of the transistor Q12(3) in the circuit 10(3). Also, one end of the drive coil ND(2) is connected to the gate (control electrode) of the transistor Q11(1) in the circuit 10(1), and the other end of the drive coil ND(2) is connected to the gate (control electrode) of the transistor Q12(1) in the circuit 10(1). Also, one end of the drive coil ND(3) is connected to the gate (control electrode) of the transistor Q11(2) in the circuit 10(2), and the other end of the drive coil ND(3) is connected to the gate (control electrode) of the transistor Q12(2) in the circuit 10(2).

[0015] In this embodiment, the power transmission coils N11(1), N12(1) and the drive coil ND(1) in the circuit 10(1) together with the power reception coil N31 of the secondary circuit 3 constitute a transformer (first transformer), the power transmission coils N11(2), N12(2) and the drive coil ND(2) in the circuit 10(2) together with the power reception coil N32 of the secondary circuit 3 constitute a transformer (second transformer), and the power transmission coils N11(3), N12(3) and the drive coil ND(3) in the circuit 10(3) together with the power reception coil N33 of the secondary circuit 3 constitute a transformer. Thus, in this embodiment, the primary circuit 2 and the secondary circuit 3 are in a state of being electrically insulated from each other, and are configured to be able to transmit power from the primary circuit 2 to the secondary circuit 3 by electromagnetic induction of the first transformer, the second transformer and the third transformer.

[0016] The phase-shifting filter F20 is provided between the drive coil ND in the same circuit 10 and the gates (control electrodes) of the transistors Q11 and Q12 in another circuit 10. Specifically, the phase-shifting filter F20(1) is provided between the drive coil ND(1) of the circuit 10(1) and the gates (control electrodes) of the transistors Q11(3) and Q12(3) of the circuit (3), the phase-shifting filter F20(2) is provided between the drive coil ND(2) of the circuit 10(2) and the gates (control electrodes) of the transistors Q11(1) and Q12(1) of the circuit (1), and the phase-shifting filter F20(3) is provided between the drive coil ND(3) of the circuit 10(3) and the gates (control electrodes) of the transistors Q11(2) and Q12(2) of the circuit (2).

[0017] The phase-shifting filter F20 is configured such that the phase of the voltage applied to each of the gates of the transistors Q11 and Q12 in another circuit 10 to which it is connected advances or lags by a phase shift amount corresponding to the number of phases of the output power with respect to the oscillation phase of the circuit 10 to which the phase-shifting filter F20 belongs. In the case of three-phase AC output as in this embodiment, the filter constant of the phase-shifting filter F20 is set such that the phase of the voltage applied to each of the gates of the transistors Q11 and Q12 in each circuit 10 is 120 degrees behind the oscillation phase of another circuit 10. Also, in the case of six-phase AC output, which is different from this embodiment, the filter constant is set such that the phase of the voltage applied to each of the gates of the transistors Q11 and Q12 in each circuit 10 is 60 degrees behind the oscillation phase of another circuit 10. As will be described later, the filter constant (circuit constant) of the phase-shifting filter F20 is set in relation to the polarity of the drive coil ND.

[0018] Thus, in this embodiment, the AC voltage induced in the drive coil ND is phase-shifted by the phase-shifting filter F20 and applied to each of the gates of the transistors Q11 and Q12 in another circuit 10. As a result, the phase of the voltage applied to each of the gates of the transistors Q11 and Q12 in another circuit 10 is shifted by a phase shift amount corresponding to the number of phases of the output power for each circuit 10 in accordance with the action of the phase-shifting filter F20, the polarity of the drive coil ND, etc. Thus, in this embodiment, three-phase AC power with phases different from each other by 120 degrees (instantaneous value becomes zero) can be output from the secondary circuit 3.

[0019] The phase-shifting filter F20 in this embodiment is composed of a resistor element R21, a coil L21, and a capacitor C21, and can also be referred to as an RLC filter. The resistor element R21 and the capacitor C21 are connected in series to the drive coil ND, and the coil L21 is connected in parallel to the drive coil ND. The phase-shifting filter F20 constitutes a low-pass filter with such a configuration, and acts to delay the phase of the AC voltage generated in the drive coil ND. As described above, the amount of phase shift by the phase-shifting filter F20 in this embodiment can be changed by adjusting the filter constants of the phase-shifting filter F20, such as the resistance value of the resistor element R21, the inductance of the coil L21, or the capacitance of the capacitor C21.

[0020] In addition to the above-described configuration, the primary circuit 2 includes a fuse FU and a capacitor C. The fuse FU disconnects the battery device BT from the primary circuit 2 when an excessive current is generated due to an abnormality in the circuit 10 of the primary circuit 2. Thereby, abnormal heating of the battery device BT due to the excessive current can be prevented. The capacitor C absorbs the voltage change accompanying the charge and discharge of the battery device BT.

[0021] 〔Secondary Circuit〕 The secondary circuit 3 includes power receiving coils N31, N32, N33, etc. As described above, the power receiving coil N31 constitutes a transformer as a secondary coil with the power transmission coils N11(1) and N12(1) of the primary circuit 2 as primary coils, and an induced electromotive force is generated by the current of the power transmission coil N11(1) or N12(1). As described above, the power receiving coil N32 forms a transformer as a secondary coil with the power transmission coils N11(2) and N12(2) of the primary side circuit 2 as the primary coils, and an induced electromotive force is generated by the current in the power transmission coil N11(2) or N12(2). As described above, the power receiving coil N33 forms a transformer as a secondary coil with the power transmission coils N11(3) and N12(3) of the primary side circuit 2 as the primary coils, and an induced electromotive force is generated by the current in the power transmission coil N11(3) or N12(3). These power receiving coils N31, N32, and N33 are connected in a Y-connection (star connection).

[0022] The phases of the AC voltages induced in each of the power receiving coils N31, N32, and N33 are mutually shifted by 120 degrees each due to the action of the phase shift filter F20 as described above, and three-phase AC power is output from the terminals (OUTPUT-U, OUTPUT-V, OUTPUT-W) connected to each of the power receiving coils N31, N32, and N33.

[0023] Hereinafter, the operation of the inverter circuit 1 in the first embodiment having the above-described configuration will be described. In the circuit 10(1), when DC power is supplied from the battery device BT to the bias circuit B10(1), the voltage divided by the resistance elements R11(1) and R12(1) is applied as a bias voltage to the gate of the transistor Q11(1), and the voltage divided by the resistance elements R13(1) and R14(1) is applied as a bias voltage to the gate of the transistor Q12. As a result, depending on the transistor characteristics and the resistance values of the resistance elements R11(1) and R13(1), either the transistor Q11(1) or Q12(1) turns on first.

[0024] At this time, when the transistor Q11(1) is turned on, current flows through the power transmission coil N11, and current flows between the drain and source of the transistor Q11(1). When a current flows through the power transmission coil N11(1) which is a primary winding, a magnetic field is generated in the first transformer, and an induced electromotive force is generated in the power reception coil N31 which is a secondary winding. The induced electromotive force generated in the power reception coil N31 can be amplified according to the winding ratio between the power transmission coil N11(1) and the power reception coil N31. When a magnetic field is generated in the first transformer, a back electromotive force is further generated in the drive coil ND(1) which is a primary winding due to self-induction.

[0025] Such an operation is similarly performed in each of the circuits 10(2) and 10(3), and an alternating voltage is similarly induced in the drive coil ND(3) of the circuit 10(3) and the drive coil ND(2) of the circuit 10(2) due to the magnetic fields generated in the second transformer and the third transformer. When an alternating voltage is induced in the drive coil ND(2) of the circuit 10(2), a negative voltage is applied to the transistor Q11(1) of the circuit 10(1), and the bias voltage applied to the transistor Q11(1) becomes below the threshold voltage, and the transistor Q11(1) becomes in an off state. On the other hand, a positive voltage is applied to the transistor Q12(1), and the bias voltage applied to the transistor Q12(1) exceeds the threshold voltage, and the transistor Q12(1) becomes in an on state. As a result, the on / off states of the transistors Q11(1) and Q12(1) are inverted.

[0026] When the transistor Q11(1) becomes in an off state and the transistor Q12(1) becomes in an on state, a current flows through the power transmission coil N12(1), and a current flows between the drain and source of the transistor Q12(1). When a current flows through the power transmission coil N12(1) which is a primary winding, a magnetic field is generated in the first transformer, and an induced electromotive force is generated in the power reception coil N31 which is a secondary winding. In this way, in each circuit 10, the on states and off states of the transistors Q11 and Q12 are alternately repeated, so that currents having different directions flow alternately through the power transmission coils N11 and N12 which are primary windings.

[0027] Here, although each circuit 10 oscillates independently, since the oscillation frequencies of the respective circuits 10 share each other's oscillation timing by the drive coil ND, each circuit 10 oscillates at the same frequency. However, in this specification, the notations "the same frequency" or "identical frequency" are used in a sense that includes minute differences in frequency that can be considered in the field of electronic circuit technology, in addition to the meaning of exactly matching frequencies.

[0028] On the other hand, the phase of the voltage applied to the gates of the transistors Q11 and Q12 of each circuit 10 is delayed by a phase shift amount corresponding to the number of phases of the output power (120 degrees in the case of three-phase AC output) with respect to the phase of the voltage generated in the power transmission coil N11 or N12 of another circuit 10, that is, the oscillation phase of the said other circuit 10, due to the action of the phase shift filter F20 connected to the gates, the polarity of the drive coil ND, etc. As a result, in this embodiment, the phase of the voltage applied to the gates of the transistors Q11(1) and Q12(1) of circuit 10(1) is set to a phase that is 120 degrees delayed with respect to the oscillation phase of circuit 10(2), the phase of the voltage applied to the gates of the transistors Q11(2) and Q12(2) of circuit 10(2) is set to a phase that is 120 degrees delayed with respect to the oscillation phase of circuit 10(3), and the phase of the voltage applied to the gates of the transistors Q11(3) and Q12(3) of circuit 10(3) is set to a phase that is 120 degrees delayed with respect to the oscillation phase of circuit 10(1).

[0029] Thereby, the on / off timing of the transistors Q11 and Q12 is shifted in each circuit 10 respectively, and the oscillation phases of the respective circuits 10 are shifted by 120 degrees each. As a result, the phases of the AC voltages induced in each of the power receiving coils N31, N32, and N33 are also shifted from each other by 120 degrees, and three-phase AC power is output. Therefore, according to this embodiment, high-frequency three-phase AC power can be output with a simple circuit configuration without the need for complicated control such as a control IC. Note that the frequency of the three-phase AC power can be set, for example, in a high-frequency band from 100 kHz to 2 MHz (megahertz) depending on the inductance, etc. of each circuit 10.

[0030] [Second Embodiment] FIG. 2 is a circuit diagram of the primary-side circuit 2 of the inverter circuit 1 in the second embodiment. The inverter circuit 1 in the second embodiment is different from the first embodiment in that a drive control coil NC is newly provided and the drive coil ND is magnetically coupled to the drive control coil NC. Hereinafter, the inverter circuit 1 in the second embodiment will be described centering on the differences from the first embodiment, and the same contents as the first embodiment will be omitted as appropriate.

[0031] Each circuit 10 further has a drive control coil NC. As shown in FIG. 2, the drive control coil NC is connected in parallel to the power transmission coils N11 and N12 and the resonance capacitor C11. Specifically, one end of the drive control coil NC is connected to one end of the power transmission coil N11, one end of the resonance capacitor C11, and the drain of the transistor Q11, and the other end of the drive control coil NC is connected to one end of the power transmission coil N12, the other end of the resonance capacitor C11, and the drain of the transistor Q12. However, the drive control coil NC is not limited to the configuration of FIG. 2, and may be connected in parallel to the resonance capacitor C11 or the power transmission coils N11 and N12 that form a resonance circuit within the same circuit 10, or may be connected in parallel to the power reception coils 31, 32, or 33 that are magnetically coupled to the power transmission coils N11 and N12 within the same circuit 10.

[0032] Furthermore, the drive control coil NC is magnetically coupled to the drive coil ND within the same circuit 10. The drive control coil NC and the drive coil ND form a transformer for drive control. For example, the drive control coil NC serves as a primary-side coil and the drive coil ND serves as a secondary-side coil to form a transformer. Therefore, in the second embodiment, the drive coil ND is not magnetically coupled to the power transmission coils N11 and N12. That is, each circuit 10 is provided with two types of transformers: a drive control transformer composed of the drive coil ND and the drive control coil NC, and a main transformer composed of the power transmission coils N11 and N12 and the power reception coils N31, N32, or N33. Here, the main transformer will be scaled up when dealing with large power, but the drive control transformer only needs to be able to capture the gate signal timings of transistors Q11 and Q12, so it can be fully realized with a small transformer.

[0033] The polarities of the drive control coil NC and the drive coil ND in the drive control transformer only need to be determined such that, together with the filter constant of the phase shift filter F20 connected to the drive coil ND, the phase of the voltage applied to the gates of transistors Q11 and Q12 via the phase shift filter F20 is shifted by a phase shift amount corresponding to the number of phases of the output power with respect to the oscillation phase of the circuit 10 to which the drive control coil NC and the drive coil ND belong. In the example of FIG. 2, the drive control coil NC is provided such that its polarity is the same as that of the power transmission coils N11 and N12 within the same circuit 10, and is also provided such that its polarity is the same as that of the drive coil ND within the same circuit 10. However, the polarities of the drive control coil NC and the drive coil ND are not limited to the example of FIG. 2. The drive control coil NC may be provided such that its polarity is opposite to that of the power transmission coils N11 and N12 within the same circuit 10, or may be provided such that its polarity is opposite to that of the drive coil ND.

[0034] In the second embodiment, in each circuit 10, an AC voltage is generated in the drive control coil NC at the oscillation frequency of each circuit 10. Accordingly, an AC voltage of the same frequency is also induced in the drive coil ND that is magnetically coupled to the drive control coil NC. Since the other circuit operations are the same as those in the first embodiment, the description thereof is omitted here.

[0035] According to the second embodiment, in addition to the same effects as the first embodiment, an additional effect of improving the degree of freedom in circuit design can be obtained. Specifically, in the first embodiment, since the drive coil ND forms the same transformer as the power transmission coils N11 and N12, the winding designs of the power transmission coils N11 and N12 and the drive coil ND had to be carried out while considering the magnitude of the output power and the gate allowable power of the transistors Q11 and Q12. However, by providing a drive control transformer separately from the main transformer, the winding design of the drive coil ND can be performed according to the gate allowable power of the transistors Q11 and Q12 without considering the magnitude of the output power.

[0036] [Modification Example of the Second Embodiment] As described above, in the second embodiment, the phase shift filter F20 was provided between the drive coil ND and the gates of the transistors Q11 and Q12 of the other circuit 10, but it may be connected to the drive control coil NC.

[0037] FIG. 3 is a circuit diagram showing a modification example of the inverter circuit 1 in the second embodiment. In this modification example, the resistance element R21 and the coil L21 of the phase shift filter F20 are connected in series with the drive control coil NC, and the capacitor C21 of the phase shift filter F20 is connected in parallel with the drive control coil NC. With such a phase shift filter F20, an AC voltage with a phase shifted by a predetermined phase shift amount with respect to the phase (oscillation phase) of the AC voltage generated in the power transmission coils N11 and N12 in each circuit 10 is induced in the drive control coil NC and the drive coil ND. As a result, the phase of the voltage applied to each gate of the transistors Q11 and Q12 connected to the drive coil ND is shifted by a phase shift amount corresponding to the number of phases of the output power with respect to the oscillation phase of that circuit 10.

[0038] Thus, in this modification example and the above-described second embodiment, there is a difference in the phase shift timing of whether to shift the phase of the AC voltage induced in the drive coil ND or the phase of the AC voltage generated in the drive control coil NC that is magnetically coupled to the drive coil ND. However, even in this modified example, the same operational effects as those of the second embodiment are achieved.

[0039] [Modified Example] The inverter circuit 1 in each of the above-described embodiments and modified examples may further include a circuit configuration other than the configurations shown in the respective figures.

[0040] Also, in each of the above-described embodiments and modified examples, a configuration for outputting three-phase AC power has been mainly exemplified. However, as long as the phases are different from each other, the number of phases of the output power is not limited to three phases, and may be two phases or four or more phases. In this case, the circuit 10 and the power receiving coil may be provided so as to have the same number as the number of phases of the output power. Also, the polarity of the drive coil ND and the circuit constants of the phase shift filter F20 may be set so that the phases of the voltages applied to the gates of the transistors Q11 and Q12 of each circuit 10 are shifted by a phase shift amount corresponding to the number of phases of the output power for each circuit. For example, when outputting four-phase AC power, the polarity of the drive coil ND and the circuit constants of the phase shift filter F20 are set so that the phase shift amount is 90 degrees. Also, when outputting nine-phase AC power, the polarity of the drive coil ND and the circuit constants of the phase shift filter F20 are set so that the phase shift amount is 140 degrees.

[0041] Also, in each of the above-described embodiments and modified examples, the circuit configurations within each circuit 10 have been made the same. However, it is not necessary for the circuit configurations within each circuit 10 to be exactly the same, and different circuit configurations corresponding to leakage, etc. may be included for each circuit 10 so that the oscillation conditions or oscillation frequencies of each circuit 10 are substantially the same.

[0042] FIG. 4 is a circuit diagram of the secondary-side circuit 3 of the inverter circuit 1 in the modified example. In each of the above-described embodiments and modified examples, an example in which the secondary-side circuit 3 is configured by a Y-connection (star connection) of the power receiving coils N31, N32, and N33 has been shown. However, the power receiving coils N31, N32, and N33 may be connected in a delta connection as shown in FIG. 4.

[0043] FIG. 5 is a circuit diagram showing a part of a modified example of the inverter circuit 1 in the second embodiment. As shown in FIG. 5, in this modified example, the phase-shifting filter F20 is composed of a capacitor C21 connected in parallel to the drive coil ND, a coil L21 connected in series to the drive coil ND, and a resistive element R21. According to this modified example, the coil L21 of the phase-shifting filter F20 may be omitted by utilizing the leakage inductance of the drive control transformer. Also in this modified example, the polarity of the drive coil ND, the circuit constants of the phase-shifting filter F20, etc. may be adjusted so that the phase of the voltage applied to each gate of the transistors Q11 and Q12 through the phase-shifting filter F20 is shifted for each circuit 10 by a phase shift amount (for example, 120 degrees) corresponding to the number of phases of the output power with respect to the oscillation phase of each circuit 10. As a result, the same effects as those of the second embodiment can be obtained. Although FIG. 5 shows a modified example of the first embodiment, the inverter circuit 1 in the second embodiment can be similarly modified.

[0044] [Application Example] The inverter circuit 1 according to the above-described embodiments and modified examples is applicable to a capacitive non-contact power supply device. FIG. 6 is a circuit diagram of the secondary-side circuit of the capacitive non-contact power supply device. The capacitive non-contact power supply device shown in FIG. 6 realizes a three-phase AC output, and coupling electrode plates C41, C42, and C43 are provided in the secondary-side circuit 3. Then, power is supplied to the loads R51, R52, and R53 through the coupling electrode plates C41, C42, and C43. Note that the primary-side circuit 2 of the capacitive non-contact power supply device may be the same as the configuration of the primary-side circuit 2 of the inverter circuit 1 in the above-described embodiments and modified examples. When comparing the required capacitance under the same conditions of frequency and the voltage between the electrode plates of the coupling electrode plates C41, C42, and C43, the three-phase AC output configuration can transmit the same power with 43% less capacitance than the single-phase AC output configuration. Therefore, according to the capacitive coupling type non-contact power supply device for three-phase AC output shown in FIG. 6, the total area of the coupling electrode plates C41, C42, and C43 can be reduced to approximately half of that in the configuration of single-phase AC output.

[0045] Examples are given below to explain the above content in more detail. However, the description of the following examples does not impose any limitation on the above content.

Example

[0046] In the example, the results of verifying the effects of the above-described first embodiment by simulation are explained with reference to FIG. 7. FIG. 7 is a graph showing the results of simulating the voltage changes at each point in the inverter circuit 1 according to the first embodiment. FIG. 7(a) shows the voltage waveform (dashed-dotted line) induced in the drive coil ND(1), the voltage waveform (broken line) generated in the coil L21(1) of the phase-shifting filter F20(1), and the voltage waveform (solid line) input to the gate of the transistor Q12(3) via the phase-shifting filter F20(1). According to FIG. 7(a), it can be seen that the phase of the voltage generated in the drive coil ND(1) of the circuit 10(1) is shifted by the phase-shifting filter F20(1) and applied to the gate of the transistor Q12(3) of the circuit 10(3). In this example, since the drive coil ND is magnetically coupled to the power transmission coils N11 and N12 with opposite polarities, the phase of the AC voltage induced in the drive coil ND(1) is 180 degrees delayed with respect to the voltage generated in the power transmission coil N11 or N12. Further, in this example, due to the filter constant of the phase-shifting filter F20, the phase of the voltage input to the gate of the transistor Q12(3) via the phase-shifting filter F20(1) is advanced by 60 degrees with respect to the voltage induced in the drive coil ND(1).

[0047] As a result, as shown in FIG. 7(b), the voltages input to the gates of the transistors Q12(3) of each circuit 10 have phases that are delayed by 120 degrees for each circuit 10. Fig. 7(b) shows the voltage waveforms (output waveforms) across the drain and source of transistors Q12(1), Q12(2), and Q12(3). According to Fig. 7(b), it can be seen that the phases of the voltages of transistors Q12(1), Q12(2), and Q12(3) are shifted by 120 degrees for each circuit 10. Fig. 7(c) shows the output waveform of the secondary circuit 3. According to Fig. 7(c), it can be seen that three-phase AC power with phases shifted by 120 degrees is output.

[0048] Thus, according to this embodiment, it has been demonstrated that a self-excited oscillation type inverter circuit capable of outputting three-phase AC power can be realized. Also, although not shown, in the inverter circuit 1 in the above-described second embodiment and various modifications, it has been demonstrated that, similar to the first embodiment, a self-excited oscillation type inverter circuit capable of outputting three-phase AC power can be realized. Furthermore, it has been demonstrated that an inverter circuit capable of outputting multi-phase AC power other than three-phase AC power can also be realized.

[0049] Some or all of the above-described embodiments and modifications can also be specified as follows. However, the above-described embodiments and modifications are not limited to the following description.

[0050] (1) An inverter circuit comprising a primary circuit having a plurality of self-excited oscillation circuits connected to a DC power supply, and a secondary circuit that outputs a plurality of phases of AC power with different phases according to the oscillation of the plurality of self-excited oscillation circuits, each of the plurality of self-excited oscillation circuits includes a power transmission coil, a resonance capacitor that forms a resonance circuit together with the power transmission coil, a pair of switching elements connected to the power transmission coil, configured to generate an induced electromotive force at a frequency corresponding to the resonance frequency of the resonance circuit, and a drive coil that applies a voltage to each control electrode of the switching element pair of another self-excited oscillation circuit in response to the induced electromotive force, a phase shift filter, and has The secondary side circuit has a plurality of power receiving coils that are magnetically coupled to the power transmission coils of the plurality of self-excited oscillation circuits, respectively. Each control electrode of the switching element pair is applied with a voltage from the drive coil of another self-excited oscillation circuit, The phase of the voltage applied to each control electrode of the switching element pair of the other self-excited oscillation circuit is shifted by a phase shift amount corresponding to the number of phases of the output power for each self-excited oscillation circuit at least due to the action of the phase shift filter. an inverter circuit. (2) At least one first drive coil of the plurality of self-excited oscillation circuits is magnetically coupled to the power transmission coil in the same self-excited oscillation circuit, The first phase shift filter in the same self-excited oscillation circuit as the first drive coil is provided between the first drive coil and each control electrode of the switching element pair of the other self-excited oscillation circuit. The inverter circuit according to (1). (3) At least one of the plurality of self-excited oscillation circuits further has a drive control coil connected in parallel to the power transmission coil or the resonance capacitor in the same self-excited oscillation circuit, or the power receiving coil magnetically coupled to the power transmission coil, At least one second drive coil of the plurality of self-excited oscillation circuits is magnetically coupled to the drive control coil in the same self-excited oscillation circuit, The second phase shift filter in the same self-excited oscillation circuit as the second drive coil is provided between the second drive coil and each control electrode of the switching element pair of the other self-excited oscillation circuit. The inverter circuit according to (1) or (2). (4) At least one of the plurality of self-excited oscillation circuits further has a drive control coil connected in parallel to the power transmission coil or the resonance capacitor in the same self-excited oscillation circuit, or the power reception coil magnetically coupled to the power transmission coil. The second drive coil of at least one of the plurality of self-excited oscillation circuits is magnetically coupled to the drive control coil in the same self-excited oscillation circuit. The phase-shifting filter in the same self-excited oscillation circuit as the second drive coil is connected to the drive control coil. The inverter circuit according to any one of (1) to (3). (5) An electric field coupling type non-contact power supply device including the inverter circuit according to any one of (1) to (4). Electric field coupling type non-contact power supply device.

Explanation of symbols

[0051] 1 Inverter circuit 2 Primary side circuit 3 Secondary side circuit BT Battery device Q11, Q12 Transistors N11, N12 Power transmission coils N31, N32, N33 Power reception coils C11 Resonance capacitor B10 Bias circuit ND Drive coil NC Drive control coil F20 Phase-shifting filter L21 Coil of the phase-shifting filter C21 Capacitor of the phase-shifting filter R21 Resistance element of the phase-shifting filter

Claims

1. An inverter circuit comprising a primary side circuit having a plurality of self-excited oscillation circuits connected to a DC power supply, and a secondary side circuit that outputs a plurality of phase alternating current powers with different phases from each other in response to the oscillation of the plurality of self-excited oscillation circuits, Each of the plurality of self-excited oscillation circuits includes a transmission coil, a resonance capacitor that forms a resonance circuit together with the transmission coil, a switching element pair connected to the transmission coil, is configured to generate an induced electromotive force having a frequency corresponding to the resonance frequency of the resonance circuit, and a drive coil that applies a voltage to each control electrode of the switching element pair of another one of the self-excited oscillation circuits in response to the induced electromotive force, a phase shift filter, and has The secondary side circuit has a plurality of power receiving coils that are magnetically coupled to the transmission coils of each of the plurality of self-excited oscillation circuits, Each control electrode of the switching element pair is applied with a voltage from the drive coil of another one of the self-excited oscillation circuits, The phase of the voltage applied to each control electrode of the switching element pair of the other one of the self-excited oscillation circuits is shifted by a phase shift amount corresponding to the number of phases of the output power for each self-excited oscillation circuit at least due to the action of the phase shift filter. Inverter circuit.

2. At least one first drive coil of the plurality of self-excited oscillation circuits is magnetically coupled to the transmission coil in the same self-excited oscillation circuit, A first phase shift filter in the same self-excited oscillation circuit as the first drive coil is provided between the first drive coil and each control electrode of the switching element pair of the other one of the self-excited oscillation circuits. The inverter circuit according to claim 1.

3. At least one of the plurality of self-excited oscillation circuits further has a drive control coil connected in parallel to the power transmission coil or the resonance capacitor in the same self-excited oscillation circuit, or the power reception coil magnetically coupled to the power transmission coil. The second drive coil of at least one of the plurality of self-excited oscillation circuits is magnetically coupled to the drive control coil in the same self-excited oscillation circuit. The second phase-shifting filter in the same self-excited oscillation circuit as the second drive coil is provided between the second drive coil and each control electrode of the switching element pair of the other one self-excited oscillation circuit. The inverter circuit according to claim 1 or 2.

4. At least one of the plurality of self-excited oscillation circuits further has a drive control coil connected in parallel to the power transmission coil or the resonance capacitor in the same self-excited oscillation circuit, or the power reception coil magnetically coupled to the power transmission coil. The second drive coil of at least one of the plurality of self-excited oscillation circuits is magnetically coupled to the drive control coil in the same self-excited oscillation circuit. The phase-shifting filter in the same self-excited oscillation circuit as the second drive coil is connected to the drive control coil. The inverter circuit according to any one of claims 1 to 3.

5. Including the inverter circuit according to any one of claims 1 to 4. An electric field coupling type non-contact power supply device.

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