JP2020089126A - Inverter device, and power transmission device of non-contact power supply system - Google Patents

Abstract

To provide an inverter device which can suppress the occurrence of a switching loss even at an advanced phase.SOLUTION: The inverter device includes: an inverter circuit 3 having the parallel connection of two arm circuits each including the series connection of two switching elements with reflux diodes in antiparallel connection; a control circuit 4 which adjusts the phase of the switching element drive signal to control the output of the inverter circuit 3; an auxiliary capacitor C2 connected in parallel with the inverter circuit 3; and auxiliary switching elements TR5, TR6 to switch connection between a DC power supply circuit 2 which outputs DC power and the auxiliary capacitor C2 and the inverter circuit 3. When a predetermined delay time elapses after either of the switching element TR3 and the switching element TR4 provided in a following arm circuit is switched on, the control circuit 4 switches on either of the auxiliary switching elements TR5, TR6.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inverter device and a power transmission device of a contactless power feeding system.

One of the methods for controlling a full-bridge type inverter circuit is phase shift control for adjusting and controlling the phase of a drive signal input to each switching element forming the inverter circuit. In the phase shift control, when the phase of the current becomes a lead phase (capacitive load) that leads the phase of the voltage, hard switching occurs in which energy loss occurs when switching the switching elements, and the switching loss increases. Patent Document 1 below discloses a full-bridge type inverter circuit that controls so as to maintain a state of a delayed phase (inductive load) in which the phase of a current signal lags the phase of a voltage signal. This inverter circuit controls the phase of the drive signal so that the phase difference between the voltage and the current in the follower arm of the leading arm and the follower arm forming the full bridge does not become smaller than a predetermined phase difference.

JP, 2016-158332, A

The phase shift control described in Patent Document 1 is based on the premise that the switching frequency is higher than the resonance frequency of the coil. Therefore, for example, when the resonance state of the coil fluctuates, the switching frequency may become lower than the resonance frequency of the coil, and the lead phase may occur. When the lead phase is reached, hard switching occurs and switching loss occurs.

Therefore, an object of the present invention is to provide an inverter device and a power transmission device of a non-contact power feeding system that can suppress the occurrence of switching loss even when the lead phase is set.

An inverter device according to an aspect of the present invention adjusts the phase of a drive signal of an inverter circuit in which two arm circuits in which two semiconductor switching elements in which diodes are connected in anti-parallel are connected in series are connected in parallel, and a drive signal of the semiconductor switching element. Circuit for controlling the output of the inverter circuit, an auxiliary capacitor connected in parallel with the inverter circuit, and an auxiliary switching element for turning on/off the connection between the DC power supply circuit for outputting DC power, the auxiliary capacitor, and the inverter circuit. And the control circuit turns on the auxiliary switching element when a predetermined delay time has elapsed after turning on any of the semiconductor switching elements.

According to this aspect, since the auxiliary switching element can be kept off until a predetermined delay time elapses after turning on one of the semiconductor switching elements, the power supply source to the inverter circuit is An auxiliary capacitor can be used instead of the DC power supply circuit. Therefore, when one of the two semiconductor switching elements in the arm circuit is switched from OFF to ON, even if the current flowing in the other diode is commutated, the auxiliary capacitor is the power supply source, The current flowing in the circuit can be suppressed so as not to become an overcurrent. Therefore, it is possible to suppress the occurrence of switching loss even when the phase is advanced.

In the above aspect, the two arm circuits are the preceding arm circuit and the following arm circuit, and the control circuit turns on any of the semiconductor switching elements in the following arm circuit, and when the delay time elapses, the auxiliary switching circuit is activated. The element may be turned on.

According to this aspect, since the auxiliary capacitor can be used as the power supply source when either one of the two semiconductor switching elements in the follower arm circuit that tends to be in the lead phase is switched from off to on, the follower arm circuit can be used. Even if the phase shifts to the phase, the current flowing in the tracking arm circuit can be suppressed from becoming an overcurrent.

In the above aspect, the control circuit may hold the auxiliary switching element in the ON state when the phase of the current signal is in the delayed phase state in which the phase of the current signal is delayed.

According to this aspect, in the case of the delay phase state, when either one of the two semiconductor switching elements in the arm circuit is switched from OFF to ON, the DC power supply circuit can be the power supply source. Therefore, as compared with the case where the auxiliary capacitor is used as the power supply source, stable and sufficient power can be supplied to the inverter circuit.

In the above aspect, the capacitance of the auxiliary capacitor may be a capacitance that can supply power to the inverter circuit including the turned-on semiconductor switching element at least until the delay time elapses.

According to this aspect, it becomes possible to store the electric power required for supplying to the inverter circuit in the auxiliary capacitor before the delay time elapses.

により算出することとしてもよい。 In the above aspect, when the capacitance of the auxiliary capacitor is C, the input power from the DC power supply circuit is V _in , the current flowing in the semiconductor switching element is i _d , and the delay time is dt,

It may be calculated by

According to this aspect, by using the equation (1), it is possible to calculate the capacitance based on the current flowing during the delay time and store the power corresponding to the capacitance in the auxiliary capacitor.

In the above aspect, the delay time may be a time that is two to five times the reverse recovery time of the diode.

According to this aspect, it is possible to set the delay time including the fluctuation amount of the reverse recovery time that occurs according to the fluctuation of the current or the voltage.

A power transmission device of a contactless power feeding system according to another aspect of the present invention includes the inverter device.

According to this aspect, the power transmission device of the contactless power feeding system can achieve the operational effects of the inverter device. For example, in the non-contact power feeding system of the magnetic field resonance method, if the distance between the power transmitting coil of the power transmitting device and the power receiving coil of the power receiving device is shortened, the phase shifts and the efficiency is reduced. With the provision of, it becomes possible to suppress the occurrence of switching loss even in the lead phase. Therefore, it is possible to further reduce the distance between the power transmission coil of the power transmission device and the power reception coil of the power reception device of the contactless power feeding system.

According to the present invention, it is possible to provide an inverter device and a power transmission device of a non-contact power supply system that can suppress the occurrence of switching loss even when the phase is advanced.

It is a figure which illustrates the circuit structure of the power transmission device of the non-contact electric power feeding system in embodiment. 3 is a chart illustrating the timing of drive signals output by the control circuit shown in FIG. 1 to each switching element. 5 is a graph illustrating a simulation result of an electronic circuit in the power transmission device illustrated in FIG. 1. 4 is a graph in which a waveform of a portion IV surrounded by a broken line shown in FIG. 3 is enlarged and displayed.

A preferred embodiment of the present invention will be described with reference to the accompanying drawings. A contactless power feeding system including an inverter device according to the embodiment is a system that wirelessly transmits high-frequency power of several kHz to several hundred kHz from a power transmitting device to a power receiving device by a magnetic field resonance method.

FIG. 1 is a diagram illustrating a circuit configuration of a power transmission device of a contactless power supply system according to an embodiment. As shown in the figure, the power transmission device 1 includes, for example, a DC power supply circuit 2, an inverter circuit 3, an auxiliary capacitor C2, auxiliary switching elements TR5 and TR6, a control circuit 4, and a power transmission coil unit 5. .. Among these components, the inverter circuit 3, the auxiliary capacitor C2, the auxiliary switching elements TR5 and TR6, and the control circuit 4 form an inverter device.

The DC power supply circuit 2 is a circuit that outputs DC power, and includes, for example, a rectifier circuit DR that rectifies three-phase AC power supplied from a commercial power supply and a smoothing capacitor C1 that smoothes the output. The DC power supply circuit 2 is not limited to one that converts AC power into DC power and outputs the DC power, and may be one that outputs DC power such as a fuel cell, a storage battery, or a solar cell.

The inverter circuit 3 is a full-bridge type inverter circuit and includes four switching elements TR1 to TR4. In the present embodiment, as the switching elements TR1 to TR4, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) such as SiC-MOSFETs and Si-MOSFETs are used, but the switching elements are not limited thereto. For example, another semiconductor switching element such as an IGBT (Insulated Gate Bipolar Transistor) may be used.

The freewheeling diodes D1 to D4 are respectively connected in parallel to the switching elements TR1 to TR4 in the opposite direction to the switching elements (inverse parallel connection). The free wheeling diodes D1 to D4 are provided to bypass the switching elements TR1 to TR4 so that the reverse current does not flow into the switching elements TR1 to TR4. The current flows through the freewheeling diodes D1 to D4, so that the switching elements TR1 to TR4 are short-circuited.

The switching element TR1 and the switching element TR2 are connected in series by connecting the source terminal of the switching element TR1 and the drain terminal of the switching element TR2. The drain terminal of the switching element TR1 is connected to the positive electrode side of the DC power supply circuit 2, and the source terminal of the switching element TR2 is connected to the negative electrode side of the DC power supply circuit 2 to form a bridge structure.

Similarly, the switching element TR3 and the switching element TR4 are connected in series to form a bridge structure. Hereinafter, the bridge structure formed by the switching elements TR1 and TR2 is referred to as a leading arm (leading arm circuit), and the bridge structure formed by the switching elements TR3 and TR4 is a follower arm (following arm circuit). Called.

An output line is connected between a connection point a between the switching element TR1 and the switching element TR2 on the leading arm and a connection point b between the switching element TR3 and the switching element TR4 on the tracking arm, and power is transmitted to the output line. The coil unit 5 is connected. A drive signal (gate signal) output from the control circuit 4 is input to the gate terminals of the switching elements TR1 to TR4.

The auxiliary capacitor C2 is connected to the DC power supply circuit 2 in parallel with the inverter circuit 3. The capacitance (electrostatic capacity) of the auxiliary capacitor C2 should be a capacity that can supply power to the inverter circuit 3 for at least a predetermined delay time described later when power is not supplied from the DC power supply circuit 2 to the inverter circuit 3. Is preferred. In addition, even if the electric power discharged from the auxiliary capacitor C2 is supplied to the inverter circuit 3 including the switching elements TR1 to TR4 in the short-circuited state, an overcurrent does not flow to the switching elements TR1 to TR4. It is preferable to set the capacitance. A specific example of the capacitance of the auxiliary capacitor C2 will be described later.

The two auxiliary switching elements TR5 and TR6 form a parallel circuit and are connected between the DC power supply circuit 2 and the auxiliary capacitor C2 and the inverter circuit 3. The auxiliary switching elements TR5 and TR6 turn on/off the connection between the DC power supply circuit 2 and the auxiliary capacitor C2 and the inverter circuit 3. The power supply from the DC power supply circuit 2 is controlled as follows by turning on and off the auxiliary switching elements TR5 and TR6.

When both the auxiliary switching elements TR5 and TR6 are off, the power from the DC power supply circuit 2 is not supplied to the auxiliary capacitor C2 and the inverter circuit 3. At this time, the electric power discharged from the auxiliary capacitor C2 is supplied to the inverter circuit 3.

On the other hand, when at least one of the auxiliary switching elements TR5 and TR6 is on, the power from the DC power supply circuit 2 is supplied to the auxiliary capacitor C2 and the inverter circuit 3.

The control circuit 4 is configured by, for example, a microcomputer including a ROM, a RAM, a CPU, an FPGA (field-programmable gate array), or the like. The control circuit 4 controls the inverter circuit 3 by phase shift control. Specifically, the control circuit 4 controls the high frequency power output from the inverter circuit 3 by adjusting the phase of the drive signal for controlling the on/off of each of the switching elements TR1 to TR4.

The control circuit 4 measures the time elapsed after turning on either the switching element TR3 or the switching element TR4 in the tracking arm, and when the measured time reaches a predetermined delay time, the auxiliary switching element TR5. And any of the auxiliary switching elements TR6 is turned on. The delay time is preferably set to be shorter as the switching frequency becomes higher and/or the capacitance of the auxiliary capacitor C2 becomes smaller. Details of the delay time will be described later.

The power transmission coil unit 5 transmits the high frequency power output from the inverter circuit 3 to the power receiving device of the contactless power feeding system in a contactless manner. The power transmission coil unit 5 is configured by, for example, a series resonance circuit including a power transmission coil L1 including a plurality of turns of a solenoid coil and a resonance capacitor C3 connected in series to the power transmission coil L1.

The resonance frequency of the series resonance circuit in the power transmission coil unit 5 is set to be equal to or lower than the switching frequency of the inverter circuit 3. The resonance frequency f can be calculated by the following equation (2) using the self-inductance L of the power transmission coil L1 and the capacitance C of the resonance capacitor C3.
f=1/{2π·√(L·C)} (2)

Next, the above-mentioned delay time will be described with reference to FIG. FIG. 2 is a chart exemplifying the timing of the drive signal output by the control circuit 4 to each of the switching elements TR1 to TR6. 2A is a drive signal to the switching element TR1, FIG. 2B is a drive signal to the switching element TR2, and FIG. 2C is a drive signal to the switching element TR3. 2D is a drive signal to the switching element TR4. 2(E) shows a drive signal to the switching element TR5, and FIG. 2(F) shows a drive signal to the switching element TR6. The horizontal axis of the timing chart is time t.

Switching element TR1 and switching element TR2 forming the leading arm are alternately turned on, and switching element TR3 and switching element TR4 forming the following arm are alternately turned on. The control circuit 4 controls the high frequency power output from the inverter circuit 3 while adjusting the phase of the drive signal on the side of the leading arm and the phase of the drive signal on the side of the following arm.

At time t1, the drive signal of the switching element TR4 switches from the off state to the on state (FIG. 2(D)). At this time, if current flows through the freewheeling diode D3 of the switching element TR3, the follower arm is short-circuited, and the current flowing through the freewheeling diode D3 is diverted to the switching element TR4, which may cause an overcurrent to flow through the follower arm. is there. If an overcurrent flows through the follower arm, switching loss will increase.

In the power transmission device 1 according to the present embodiment, both the auxiliary switching elements TR5 and TR6 are turned off at time t1 (FIGS. 2E and 2F). Therefore, the power from the DC power supply circuit 2 is not supplied to the inverter circuit 3, but the power from the auxiliary capacitor C2 is supplied. As described above, the capacitance of the auxiliary capacitor C2 is set within the range in which the overcurrent does not flow through the switching elements TR1 to TR4 due to the electric power discharged from the auxiliary capacitor C2. Therefore, it is possible to prevent the overcurrent from flowing to the follower arm, and it is possible to suppress the occurrence of switching loss.

At time t2, the drive signal of the auxiliary switching element TR5 switches from the off state to the on state (FIG. 2(E)). As a result, the electric power from the DC power supply circuit 2 is supplied to the inverter circuit 3.

The time from time t1 to time t2 is the delay time Td described above. The delay time Td is set to be longer than the time (reverse recovery time) during which the current flows through the freewheeling diode D3 after the switching element TR4 is turned on, and after the switching element TR4 is turned on, for example. It is preferable that the time is set to be shorter than the time until the power of the auxiliary capacitor C2 becomes insufficient. Specific examples of the delay time Td and the capacitance of the auxiliary capacitor C2 will be described below.

The delay time Td can be calculated using, for example, the reverse recovery time of the free wheeling diode. The reverse recovery time is predetermined as the standard of the free wheeling diode, and is described in, for example, the data sheet of the switching element. The reverse recovery time of the free wheeling diode varies depending on the current and voltage of the circuit. Therefore, it is preferable to set the delay time Td to a time that is about 2 to 5 times the reverse recovery time, in consideration of the margin generated by such a variation.

When calculating the delay time Td, the delay time Td is set so that the time obtained by adding the delay time Td and the dead time of the switching element falls within the range of 10% to 15% of 1/2 of the switching frequency period. It is preferable to calculate. The dead time is a period in which both two switching elements in the same arm are turned off, and can be calculated by adding the turn-off delay time and the fall time after turn-off. The turn-off delay time and the fall time after turn-off are predetermined as the standard of the switching element, and are described in, for example, the data sheet of the switching element.

The capacitance C of the auxiliary capacitor C2 can be calculated by the following equation (3) using the delay time Td. V _in of the equation (3) is an input voltage from the DC power supply circuit 2, i _d is a current flowing through the switching element (including the freewheeling diode), and dt is the delay time Td.

Illustratively, the input voltage V _in is the 282 [V], a current i _d is 50 [A], the capacitance C of the auxiliary capacitor C2 when the delay time dt is (45 [ns] × 5) When calculated using the equation (3), it becomes about 40 [nF] as follows.
C={50×(45×10 ⁻⁹ ×5}}/282=39.9×10 ⁻⁹ ≈40 [nF]

Here, (45 [ns]×5) set to the delay time dt indicates that the reverse recovery time of the free wheeling diode is 45 [ns], and that the reverse recovery time is quintupled. This is an example of the case where dt includes a variation margin of the reverse recovery time.

In this example, the dead time of the switching element is 0.5 [μs] and the switching frequency is 85 [kHz]. In this case, the time obtained by adding the delay time Td and the dead time of the switching element is (0.045 [μs]×5)+0.5 [μs]=0.725 [μs]. Moreover, 1/2 of the cycle of the switching frequency is 11.76 [μs]/2=5.88 [μs].

Therefore, the ratio of the time obtained by adding the delay time Td and the dead time of the switching element to 1/2 of the cycle of the switching frequency is 0.725 [μs]/5.88 [μs]×100=12. It becomes 0.3%. In other words, the time obtained by adding the delay time Td and the dead time of the switching element is 12.3%, which is 1/2 the cycle of the switching frequency.

In this case, the time obtained by adding the delay time Td and the dead time of the switching element falls within the range of 10% to 15% of 1/2 of the cycle of the switching frequency. Therefore, in this example, setting the delay time dt to (45 [ns]×5) can be determined to be within the range of the allowable condition.

Returning to the explanation of FIG. Similar to the time t1 to the time t2 described above, the time from the time t3 to the time t4 is the delay time Td described above. The operation from time t3 to time t4 will be described below.

At time t3, the drive signal of the switching element TR3 switches from the off state to the on state (FIG. 2(C)). At this time, if a current is flowing through the freewheeling diode D4 of the switching element TR4, the follower arm is short-circuited, and the current flowing through the freewheeling diode D4 is commutated to the switching element TR3, and an overcurrent may flow through the follower arm. is there. If an overcurrent flows through the follower arm, switching loss will increase.

In the power transmission device 1 according to this embodiment, both the auxiliary switching elements TR5 and TR6 are turned off at time t3 (FIGS. 2E and 2F). Therefore, the power from the DC power supply circuit 2 is not supplied to the inverter circuit 3, but the power from the auxiliary capacitor C2 is supplied. Therefore, it is possible to prevent the overcurrent from flowing to the follower arm, and it is possible to suppress the occurrence of switching loss.

At time t4, the drive signal of the auxiliary switching element TR6 switches from the off state to the on state (FIG. 2(F)). As a result, the electric power from the DC power supply circuit 2 is supplied to the inverter circuit 3.

With reference to FIG. 3 and FIG. 4, it will be described that in the power transmission device 1 according to the present embodiment, the occurrence of switching loss can be suppressed even when the lead phase is set.

FIG. 3 is a graph illustrating a simulation result of an electronic circuit in the power transmission device 1 illustrated in FIG. 1, and FIG. 4 is a graph in which a waveform of a portion IV surrounded by a wavy line illustrated in FIG. 3 is enlarged and displayed.

3A and 4A are drive signals to the switching elements TR1 and TR2, and FIG. 3B and FIG. 4B are drive signals to the switching elements TR3 and TR4. FIG. 3C and FIG. 4C show drive signals to the switching elements TR5 and TR6 (collectively displayed as one drive signal). 3D and 4D are the voltage signal V _TR1 and the current signal I _TR1 in the switching element TR1, and FIGS. _3E and 4E are the voltage signal V _TR2 in the switching element TR2. And the current signal I _TR2 . _3F and 4F are the voltage signal V _TR3 and the current signal I _TR3 in the switching element TR3, and FIGS. 3G and 4G are the voltage signal V _TR4 in the switching element TR4. And the current signal I _TR4 .

3(H) and 4(H) are the voltage signal V _out and the current signal I _out in the power transmission coil unit 5, and FIGS. 3(I) and 4(I) show the auxiliary switching elements TR5 and TR6. The voltage signal V _TR5 and the current signal I _TR5 (collectively displayed as one voltage signal and current signal). 3(J) and 4(J) show the current signal I _DR input to the inverter circuit 3 and the current signal I _C2 flowing through the auxiliary capacitor C2.

The horizontal axis of the graph represents time, and the vertical axis represents voltage value or current value. The voltage value on the vertical axis is represented by a value of 1/10. In addition, the simulation is performed by setting the voltage of the DC power supply circuit 2 to 240 [V] and the capacitance of the auxiliary capacitor C2 to 30 [nF]. Further, in order to easily reproduce the lead phase, the resonance frequency of the series resonance circuit in the power transmission coil unit 5 and the switching frequency of the inverter circuit 3 are set to the same value.

As shown in FIG. 3, in the switching element TR1 and the switching element TR2 that form the leading arm, the phase of the current signal is a lag phase that lags the phase of the voltage signal (FIGS. 3A and 3D). (E)). On the other hand, in the switching element TR3 and the switching element TR4 that form the follow-up arm, the phase of the current signal is a lead phase that leads the phase of the voltage signal (FIGS. 3B, 3F, 3G).

In the case of the lead phase, if the auxiliary capacitor C2 and the auxiliary switching elements TR5 and TR6 are not provided, when one of the switching element TR3 and the switching element TR4 is switched from off to on, the current flowing through the other return diode. Are commutated, an overcurrent flows in the following arm, and a switching loss occurs.

In the power transmission device 1 according to the present embodiment, the auxiliary capacitor C2 and the auxiliary switching elements TR5 and TR6 are provided to prevent an overcurrent from flowing to the tracking arm. This will be specifically described with reference to FIG.

At time t1, when the switching element TR4 is switched from OFF to ON (FIG. 4(B)), the current (FIG. 4(F)) flowing in the return diode D3 of the switching element TR3 is rectified to the switching element TR4 (FIG. 4B). 4(G)), the voltage of the switching element TR3 rises (FIG. 4(F)). At this time, since the auxiliary switching elements TR5 and TR6 are turned off (FIG. 4(C)), the power from the DC power supply circuit 2 is not supplied, but the power is supplied from the auxiliary capacitor C2. The free wheeling diode D3 of the switching element TR3 is turned off by applying a reverse voltage (FIG. 4(F)).

After that, with the discharge of the auxiliary capacitor C2 (FIG. 4(J)), the voltage of the switching element TR3 gradually decreases (FIG. 4(F)). Then, at time t2 when the delay time Td has elapsed from time t1, the auxiliary switching element TR5 is switched from off to on (FIG. 4(C)).

As shown in FIGS. 4F and 4G, after the time t1, the currents of the switching element TR3 and the switching element TR4 do not project, and the overcurrent does not flow through the switching element TR3 and the switching element TR4. Can be confirmed.

As described above, according to the power transmission device 1 of the contactless power feeding system in the embodiment, the auxiliary switching element is provided until the delay time Td elapses after the switching element TR3 or the switching element TR4 in the tracking arm is turned on. Both TR5 and TR6 can be kept off. Therefore, the power supply source to the inverter circuit 3 can be the auxiliary capacitor C2 instead of the DC power supply circuit 2.

As a result, when one of the switching element TR3 and the switching element TR4 in the tracking arm is switched from off to on, even if the current flowing in the other diode is commutated, the auxiliary capacitor C2 is the power supply source. Therefore, the current flowing through the follower arm can be suppressed from becoming an overcurrent.

Therefore, according to the power transmission device 1 of the contactless power feeding system in the embodiment, it is possible to suppress the occurrence of switching loss even when the phase is advanced.

Here, in the magnetic field resonance type non-contact power feeding system, when the distance between the power transmitting coil of the power transmitting device and the power receiving coil of the power receiving device is shortened, the output of the inverter circuit is narrowed, and as a result, There is a problem in that the efficiency becomes low due to the phase. However, according to the power transmitting device 1 of the contactless power feeding system in the embodiment, it is possible to suppress the occurrence of switching loss even in the lead phase, and therefore, between the power transmitting coil of the power transmitting device and the power receiving coil of the power receiving device of the contactless power feeding system. It becomes possible to further reduce the distance.

[Modification]
The embodiments described above are for facilitating the understanding of the present invention and are not for limiting the interpretation of the present invention. Each element included in the embodiment and its arrangement, material, condition, shape, size and the like are not limited to the exemplified ones and can be appropriately changed.

In the above-described embodiment, the control circuit 4 turns off both the auxiliary switching element TR5 and the auxiliary switching element TR6 until the delay time elapses after turning on either the switching element TR3 or the switching element TR4 in the tracking arm. However, the ON/OFF control of the auxiliary switching elements TR5 and TR6 is not limited to this. For example, when the phase is the delay phase, the control circuit 4 may hold at least one of the auxiliary switching element TR5 and the auxiliary switching element TR6 in the ON state.

In this case, the control circuit 4 may hold the ON state of the auxiliary switching elements TR5 and TR6 without turning them OFF while detecting the delay phase. In the case of the delay phase, the switching loss is less affected, so that it is possible to supply stable and sufficient power to the inverter circuit by operating the DC power supply circuit 2 as the power supply source.

Further, in the above-described embodiment, the case where the two auxiliary switching elements TR5 and TR6 are provided has been described, but the number of auxiliary switching elements is not limited to two, and may be one or three. It may be more than one. By connecting a plurality of auxiliary switching elements in parallel, the number of times of switching of the auxiliary switching elements can be reduced, so that the life of the auxiliary switching elements can be extended.

Further, in the above-described embodiment, when any one of the switching element TR3 and the switching element TR4 in the tracking arm is turned on, a delay time is waited, and then either the auxiliary switching element TR5 or the auxiliary switching element TR6 is turned on. Although it is turned on, the timing for providing the delay time is not limited to this. In the embodiment, in consideration of the fact that the follow-up arm is likely to be in the lead phase, when the switching element in the follow-up arm is turned on, a mode in which the auxiliary switching element is turned on after the delay time is waited for is described. There is. However, it can also be envisaged that the leading arm will be in phase advance. Therefore, when the leading arm is in the lead phase, when the switching element in the leading arm is turned on, a delay time may be waited, and then the auxiliary switching element may be turned on.

Further, in the above-described embodiment, the case where the inverter device is applied to the power transmission device 1 of the contactless power feeding system has been described, but the system to which the inverter device is applied is not limited to this, and any system having an inverter circuit is described. Can be applied to.

DESCRIPTION OF SYMBOLS 1... Power transmission device, 2... DC power supply circuit, 3... Inverter circuit, 4... Control circuit, C2... Auxiliary capacitor, D1, D2, D3, D4... Reflux diode, TR1, TR2, TR3, TR4... Switching element, TR5, TR6... Auxiliary switching element

Claims (7)

An inverter circuit in which two arm circuits in which two semiconductor switching elements in which diodes are connected in anti-parallel are connected in series are connected in parallel;
A control circuit that controls the output of the inverter circuit by adjusting the phase of the drive signal of the semiconductor switching element;
An auxiliary capacitor connected in parallel with the inverter circuit,
An auxiliary switching element that turns on and off the connection between the DC power supply circuit that outputs DC power and the auxiliary capacitor and the inverter circuit;
The control circuit turns on the auxiliary switching element when a predetermined delay time has elapsed after turning on any of the semiconductor switching elements,
Inverter device. The two arm circuits are the leading arm circuit and the following arm circuit,
The control circuit turns on the auxiliary switching element when the delay time elapses after turning on any one of the semiconductor switching elements in the tracking arm circuit,
The inverter device according to claim 1. The control circuit holds the auxiliary switching element in an ON state when the phase of the current signal is in a delay phase state in which the phase of the current signal is delayed.
The inverter device according to claim 1. The capacitance of the auxiliary capacitor is a capacitance capable of supplying electric power to the inverter circuit including the semiconductor switching element which is turned on, at least until the delay time elapses.
The inverter device according to any one of claims 1 to 3. When the capacitance of the auxiliary capacitor is C, the input power from the DC power supply circuit is V _in , the current flowing through the semiconductor switching element is i _d , and the delay time is dt,

Can be calculated by
The inverter device according to any one of claims 1 to 4. The delay time is a time obtained by multiplying the reverse recovery time of the diode by 2 to 5 times.
The inverter device according to any one of claims 1 to 5. A power transmission device of a contactless power feeding system, comprising the inverter device according to claim 1.

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