JP2024000473A - Single-phase three-wire ac power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an effect by reducing power loss generated in a conventional circuit which creates a single-phase three-wire AC power source from a DC power source.

SOLUTION: An inverter circuit is formed of first to fourth switch elements, a first reactor, and a second reactor. In the inverter circuit, a bidirectional switch circuit is connected between a connection point between the first and second switch elements and a connection point between the third and fourth switch elements, a drive signal of a prescribed cycle, a prescribed phase, and a prescribed pulse width is applied to the first to fourth switch elements and a control terminal of the bidirectional switch circuit, and excitation energy in the first reactor and the second reactor is discharged via the bidirectional switch circuit.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a power supply device that can mutually convert DC power and AC power.

Devices that generate AC power from electric vehicle (EV) batteries are increasingly being used during power outages. Additionally, in order to supply AC power to the entire building evacuated to in the event of a disaster, AC generated from EVs is also connected to the building's power distribution board.
When connecting alternating current to a switchboard, it is necessary to disconnect from the grid once and supply single-phase three-wire alternating current.
A single-phase three-wire AC inverter has three output terminals, and if they are named L1, N, and L2, the voltage is 100V between L1 and N and N and L2, and 200V between L1 and L2. occurs. Further, N is protectively grounded.
A single-phase three-wire AC inverter uses a different circuit and a different control method from a single-phase two-wire AC inverter that generates one AC voltage.

Patent Document 1 discloses an inverter circuit that generates single-phase three-wire alternating current. According to the disclosed circuit, a direct current voltage is divided by two capacitors connected in series, and a single-phase three-wire alternating current is generated from each voltage via an inverter circuit.

JP 2014-79133 Publication

FIG. 2 of Patent Document 1 shows a current path in discharge operation 1. In the figure, when Q1 and Q4 are turned on, the charge in capacitor C1 flows to one load via Q1 and L1, and the charge in capacitor C2 flows to the other load via Q4 and L2.

Next, when Q1 and Q4 are turned off and Q2 and Q3 are turned on, the excitation energy of L1 passes through one load and is regenerated to capacitor C2, and the excitation energy of L2 passes through the other load and is regenerated to capacitor C1. .

In other words, the charge energy discharged from capacitors C1 and C2 is supplied to the load and at the same time is stored as excitation energy for L1 and L2, but part of the stored energy is returned to capacitors C1 and C2. Therefore, an energy catch-up occurs between the capacitors (C1 and C2) and the reactors (L1 and L2), resulting in power loss.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a highly efficient inverter that does not cause the energy catch-and-play that occurs in conventional single-phase three-wire AC inverters.

In a conventional single-phase three-wire AC inverter, when the output is under no load or light load, the voltage increases and the waveform deviates from a sine wave.

Another object of the present invention is to provide a single-phase three-wire AC inverter in which the voltage does not rise even when the load becomes no load or light load, and the AC voltage waveform does not deviate from a sine wave. The purpose is

In order to achieve the above object, the present invention includes a first DC power supply, a series circuit including a first capacitor and a second capacitor connected in parallel to the first DC power supply, and a first DC power supply. A series circuit consisting of a first switch element and a second switch element connected in parallel to the first DC power supply, and a series circuit consisting of a third switch element and a fourth switch element connected in parallel to the first DC power supply. , a bidirectional switch circuit connected between the connection point of the first switch element and the second switch element and the connection point of the third switch element and the fourth switch element, and one of the bidirectional switch circuits. A third capacitor connected between the terminal and the connection point of the first capacitor and the second capacitor, and a third capacitor connected between the other terminal of the bidirectional switch circuit and the connection point of the first capacitor and the second capacitor. a fourth capacitor connected to the first reactor, a first reactor inserted in series to the bidirectional switch circuit side terminal of the third capacitor, and a first reactor inserted in series to the bidirectional switch circuit side terminal of the fourth capacitor; the second reactor, the first load connected in parallel to the third capacitor, the second load connected in parallel to the fourth capacitor, and the first reactor side of the third capacitor. a third load connected between the terminal and the terminal on the second reactor side of the fourth capacitor; It is characterized in that a drive signal having a phase and a pulse width is applied, thereby converting the power of the first DC power source into AC power and supplying it to the first to third loads.

According to the present invention, higher efficiency than conventional single-phase three-wire AC inverters can be obtained.

1 is a circuit diagram showing an embodiment of the present invention. FIG. FIG. 3 is a circuit diagram showing another embodiment of the present invention. FIG. 3 is a circuit diagram showing another embodiment of the present invention. FIG. 3 is a waveform diagram for explaining the operation of the circuit of the present invention. FIG. 3 is a waveform diagram for explaining the operation of the circuit of the present invention. FIG. 3 is a circuit diagram showing the discharge current of the present invention. FIG. 2 is a circuit diagram showing a conventional discharge current.

る信号であるため、ＭＯＳＦＥＴ４ないし７とＭＯＳＦＥＴ８と９が同時にオン状態になることはない。FIG. 1 shows a circuit of a power conversion device showing an embodiment of the present invention. The voltage of DC power supply 1 is divided by capacitors 2 and 3. MOSFETs 4 and 7 have a first signal, a pulse that is high only for a period corresponding to the positive half wave of the AC voltage (hereinafter referred to as "AC positive"), and a third signal, which is proportional to the amplitude of the AC voltage. An AND signal (hereinafter referred to as "&") of pulses (hereinafter referred to as "DT") having a duty ratio of 1 is added. A pulse (hereinafter referred to as "AC negative") that is high only during a period corresponding to the negative half wave of the AC voltage, which is the second signal source, and & of DT are applied to the switching elements 5 and 6. The gates of MOSFETs 8 and 9 receive a fourth signal, a complementary signal of DT.

Therefore, MOSFETs 4 to 7 and MOSFETs 8 and 9 are not turned on at the same time.

The relationship between the AC waveform and the AC positive and AC negative signals is shown in FIG.

When AC positive &DT becomes high and is applied to the gates of MOSFETs 4 and 7, the charge in capacitor 2 flows through MOSFET 4, reactor 12, and capacitor 10, and the charge in capacitor 3 flows through MOSFET 7, reactor 13, and capacitor 11.

Ｔ８と９を通りコンデンサ１０と１１を充電する。Even if the AC positive pulse is high, when DT becomes low, MOSFETs 4 and 7 are turned off. one

It passes through T8 and 9 and charges capacitors 10 and 11.

FIG. 6 shows the current that excites the reactors 12 and 13 in FIG. 1 and the current path when the excitation energy is released.

１とＬ２を励磁する電流は図６の回路と同じであるが、Ｑ１とＱ４がオフして、Ｑ２とＱ３がオンになるとリアクトルＬ１とＬ２の励磁エネルギの一部は入力コンデンサＣ１とＣ２に戻るが、図６の回路ではリアクトル（１２と１３）の励磁エネルギは出力コンデンサ（１０と１１）だけを充電する。すなわち、図６と図７では励磁エネルギの放出の電流経路が異なっている。FIG. 7 is an equivalent circuit of FIG. 2 of Patent Document 1, which is one of the conventional circuit configurations.

The current that excites 1 and L2 is the same as the circuit in Figure 6, but when Q1 and Q4 are turned off and Q2 and Q3 are turned on, part of the excitation energy of reactors L1 and L2 is transferred to input capacitors C1 and C2. Returning to the circuit of FIG. 6, the excitation energy of the reactors (12 and 13) charges only the output capacitors (10 and 11). That is, the current paths for emitting excitation energy are different between FIGS. 6 and 7.

In the conventional method shown in FIG. 7, part of the excitation energy returns to C1 and C2, resulting in poor conversion efficiency. Furthermore, if there is a difference in the AC power extracted from C3 and C4, a difference will occur between the voltages of C1 and C2, so as shown in FIG. circuit is required, and this balance circuit also causes power loss.

の振幅に比例するデューティ比であるが、従来方式ではＤＴの値は交流電圧に単純に比例

The duty ratio is proportional to the amplitude of DT, but in the conventional method, the value of DT is simply proportional to the AC voltage.

FIG. 2 shows a power conversion device showing another embodiment of the present invention. The difference from FIG. 1 is that the gates of MOSFETs 8 and 9 constituting the bidirectional switch circuit are separate, and AC positive and AC negative signals are applied to each.

In FIG. 2, AC positive &DT is applied to MOSFETs 4 and 7, and AC positive is applied to the gate of MOSFET 9 of the bidirectional switch circuit constituted by MOSFETs 8 and 9. While the AC positive pulse is high, conduction occurs only in the direction from the bottom to the top of the diagram of the bidirectional switch circuit.

When the AC positive pulse is high and DT is high, switch elements 4 and 7 are turned on, and the current passes through reactors 12 and 13, exciting both reactors and charging capacitors 10 and 11. When DT becomes low even while the AC positive pulse is high, MOSFETs 4 and 7 are turned off, and the excitation energy of reactors 12 and 13 flows through the body diodes of MOSFET 9 and MOSFET 8, which become conductive in the direction of excitation energy release. released.

When the AC negative pulse is high and DT is high, MOSFETs 6 and 5 are turned on, and the current passes through reactors 13 and 12, exciting both reactors and charging capacitors 11 and 10. When DT becomes low even while the AC negative pulse is high, MOSFETs 6 and 5 are turned off, and the excitation energy of reactors 13 and 12 flows through the body diodes of MOSFET 8 and MOSFET 9, which become conductive in the direction of excitation energy release. released.

オンオフするか、または交流正と交流負の周期でオンオフするかという点にある。

It depends on whether it turns on and off, or whether it turns on and off in cycles of positive AC and negative AC.

方がローの状態であるデッドタイムを設けるが、それが効率を下げる原因の１つになる。

However, dead time is provided, which is a low state, which is one of the causes of lower efficiency.

In FIG. 2, current flows through the body diode of one of MOSFETs 8 and 9, so a loss occurs due to the forward drop voltage (VF) of the diode, which is one of the causes of lower efficiency.

Ｒ信号を加える。FIG. 3 is an example of a circuit for improving each of the losses shown in FIGS. 1 and 2, and is a bidirectional switch circuit.

Add R signal.

In FIGS. 1 to 3, all or part of the MOSFETs may be replaced by IGBTs and diodes connected in antiparallel.

The single-phase three-wire AC inverter of the present invention is the same as the conventional single-phase two-wire AC inverter in that it is only necessary to make DT proportional to the amplitude of the AC voltage. Therefore, the AC voltage supplied to the three loads is stable, and the AC waveform also maintains a sine wave regardless of the load.

1 DC power supply 2, 3, 10, 11 Capacitor 4 to 9 MOSFET
12, 13 Reactor 14, 15, 16 Load 17 Signal source

Claims (4)

a first DC power supply; a series circuit including a first capacitor and a second capacitor connected in parallel to the first DC power supply; and a first switch element connected in parallel to the first DC power supply; a series circuit consisting of a second switch element, a series circuit consisting of a third switch element and a fourth switch element connected in parallel to the first DC power supply, the first switch element and the second switch; a bidirectional switch circuit connected between a connection point of the element and a connection point of the third switch element and the fourth switch element, one terminal of the bidirectional switch circuit, the first capacitor, and the fourth switch element; a third capacitor connected between the connection point of the second capacitor, the other terminal of the bidirectional switch circuit, and a fourth capacitor connected between the connection point of the first capacitor and the second capacitor; a first reactor inserted in series with a terminal of the bidirectional switch circuit side of the capacitor and the third capacitor; and a second reactor inserted in series with the terminal of the fourth capacitor on the bidirectional switch circuit side. a first load connected in parallel to the reactor and the third capacitor; a second load connected in parallel to the fourth capacitor; a terminal of the third capacitor on the first reactor side; A third load connected between terminals of the fourth capacitor on the second reactor side, a predetermined period and phase for each control electrode of the first to fourth switch elements and the bidirectional switch circuit. and a signal source that applies a drive signal having a pulse width, thereby converting the power of the first DC power source into AC power and supplying the AC power to the first to third loads. 3-wire AC power converter. The bidirectional switch circuit includes a first control electrode that controls conduction in one direction and a second control electrode that controls conduction in another direction, and the signal source is a positive half-wave of an alternating current voltage. a first signal that outputs a pulse for a period corresponding to the negative half wave of the AC voltage, a second signal that outputs a pulse for a period corresponding to the negative half wave of the AC voltage, and a duty ratio that is proportional to the amplitude of the sine wave of the AC voltage. A third signal that outputs a pulse and a fourth signal that outputs a complementary signal of the third signal, and the control electrodes of the first switch element and the fourth switch element are connected to the first signal An AND signal of the third signal is added, an AND signal of the second signal and the third signal is applied to the control electrodes of the second switch element and the third switch element, and the bidirectional switch circuit 2. The single-phase three-wire AC power converter according to claim 1, wherein said fourth signal is applied to said first and second control electrodes. The first signal is applied to the first control electrode of the bidirectional switch circuit instead of the fourth signal, and the first signal is applied to the second control electrode of the bidirectional switch circuit instead of the fourth signal. 3. The single-phase three-wire AC power converter according to claim 2, wherein two signals are added. The first signal and the fourth signal are ORed to a first control electrode of the bidirectional switch circuit, and the second signal and the fourth signal are ORed to a second control electrode of the bidirectional switch circuit. 3. The single-phase three-wire AC power converter according to claim 2, wherein the signals are added by OR.

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