JPH11341831A - Partial resonance single-phase pwm full-bridge inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a partial resonance single-phase PWM full-bridge inverter, whose number of parts has been curtailed sharply by reducing the numbers of auxiliary switches, drive circuits, and so on. SOLUTION: This single-phase PWM full-bridge inverter is provided with first and second main switching elements Q1 , Q2 connected in series, third and fourth main switching elements Q3 , Q4 connected in series, current returning diodes G1 -G4 and capacitors for resonance C1 -C4 connected in parallel with the main switching elements Q1 -Q4 . Here, a first auxiliary switch Qa, a reactor for resonance L3 , and a second auxiliary switch Qb are connected in series, between an intermediate junction H1 of the first and second main switching elements Q1 , Q2 , and an intermediate junction H2 of the third and fourth main switching elements Q3 , Q4 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial resonance single-phase PWM full-bridge inverter in which four main switch elements are turned on and off to obtain an AC voltage.

[0002]

2. Description of the Related Art As shown in FIG. 3, a partial resonance single-phase PWM full-bridge inverter 1 having a partial resonance circuit for reducing switching loss has been conventionally known.

[0003] This partial resonance single-phase PWM full-bridge inverter 1 has two main switch elements S1, connected in series.
S2 and two main switch elements S3 and S4 connected in series. The main switch elements S1 and S2 and the main switch elements S3 and S4 are connected between both terminals of the DC power supply E. Each main switch element S1 to S4 has a freewheel diode D
1 to D4 and resonance capacitors C1 to C4 are connected in parallel.

A third auxiliary switch Sc, a resonance reactor L2 and a third auxiliary switch Sc are provided between a connection point A of capacitors Ca and Cb for dividing the power supply voltage E into two and an intermediate connection point B of the main switch elements S1 and S2. A first auxiliary switch Sa, a resonance reactor L1, and a second auxiliary switch Sb are connected between a connection point A and an intermediate connection point C between the main switch elements S3 and S4. They are connected in series.

The main switch elements S1 to S4 and the auxiliary switch S
a to Sd are driven by drive circuits K1 to K4 and Ka to Kd, and independent power supply voltages E1 to E4 are used for this drive.

The operation shown in FIG. 4 and FIG. 5 shows a state in which a current IO flows through the freewheel diodes D2 and D3 and commutates to the main switch elements S1 and S4. Here, for convenience of explanation, an operation when commutating to the main switch element S1 from a state in which the current IO flows through the freewheel diode D2 will be described.

Assuming that the current IO during the commutation period is constant, the current IL flowing through the resonance reactor L1 starts to rise linearly by turning on the resonance auxiliary switch Sb at the time point t0. Here, t0 to t1 is the time until the current IL reaches the output current I0, and t1 to t2 is the period during which the current ΔIL that determines the resonance energy flows.

When the main switch element S2 is turned off by the drive circuit K2 (time t2), the resonance reactor L1 and the resonance capacitors C1 and C2 enter a resonance operation.
The output voltage VO increases. When the output voltage VO reaches the power supply voltage E (time t3), the free wheel diode D1 turns on. If a pulse signal is output from the drive circuit K1 to turn on the main switch element S1 at a time tx within the period (time t3 to t4) in which the freewheeling diode D1 is on, zero voltage switching is performed. Become. Time points t6 to t9 indicate a state in which the current IO flows through the freewheeling diode D1 and commutates to the main switching element S2, and the operation of the time points t0 to t9 is repeated. Period t3 to t7, that is, FIG.
By changing the width of the output voltage Vo, an AC voltage is obtained as shown by a broken line.

[0009]

In such a partial resonance single-phase PWM full-bridge inverter, as shown in FIG. 4, a commutation resonance current IL and an output current IO are supplied to the auxiliary switches Sa to Sd. Therefore, a large current equivalent to that of the main switch elements S1 to S4 flows. For this reason, the main switch element S1 is also provided to the auxiliary switches Sa to Sd.
It is necessary to use four elements having a small current loss and a large current rating equivalent to that of S4, resulting in a problem of high cost.

Further, since four auxiliary switches Sa to Sd are used, the number of drive circuits K1 to K4, Ka to Kd is large, and the number of drive circuit DC power supplies E1 to E4 is also large.
Further, since the capacitors Ca and Cb for dividing the main power supply voltage E into two parts are required, there is a problem that the number of parts becomes very large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the number of auxiliary switches, drive circuits, and the like, thereby reducing the number of parts to a large extent. An object of the present invention is to provide a bridge inverter.

[0012]

In order to achieve the above object, the present invention provides first and second main switch elements connected between both terminals of a DC power supply and connected in series, and both ends of the DC power supply. Third and fourth main switch elements connected in series and connected in series, a first freewheeling diode and a first resonance capacitor connected in parallel to the first main switch element, and a third main switch element connected in parallel to the second main switch element. The second return diode and the second capacitor for resonance connected in parallel, the third return diode and the third capacitor for resonance connected in parallel to the third main switch element, and the fourth return diode connected in parallel to the fourth main switch element A single-phase PWM full-bridge inverter comprising a diode and a fourth capacitor for resonance, comprising: an intermediate connection point between first and second main switch elements;
A first auxiliary switch, a resonance reactor, and a second auxiliary switch are connected in series between an intermediate connection point of the main switch elements.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a partial resonance single-phase PWM full-bridge inverter according to the present invention will be described below with reference to the drawings.

The partial resonance single-phase PWM full-bridge inverter 20 shown in FIG. 1 is connected in series with two main switch elements Q1 (first main switch element) and Q2 (second main switch element) connected in series. Two main switch elements Q3
(Third main switch element) and Q4 (fourth main switch element). The main switch elements Q1, Q2 and the main switch elements Q3, Q4 are connected between both terminals of the DC power supply E. Each of the main switching elements Q1 to Q4 includes a freewheeling diode (first to fourth freewheeling diodes) G1 to G4.
And resonance capacitors (the first resonance capacitor to the fourth resonance capacitor) C1 to C4 are connected in parallel.

A first auxiliary switch Qa, a resonance reactor L3, and a second auxiliary switch Qb are provided between an intermediate connection point H1 between the main switch elements Q1 and Q2 and an intermediate connection point H2 between the main switch elements Q3 and Q4. They are connected in series.

The main switch Q1 and the auxiliary switch Qa are turned on / off by a drive circuit 21 and a drive circuit 22, and 30 is a DC power supply for the drive circuits 21 and 22. The main switch Q3 and the auxiliary switch Qb are turned on and off by the drive circuits 23 and 24, and 31 is a DC power supply for the drive circuits 23 and 24. The main switches Q2 and Q4 are turned on and off by drive circuits 25 and 26, and 32 is a DC power supply for the drive circuits 25 and 26. In addition, DC power supply 30 ~
32 are independent of each other.

Next, the partial resonance single-phase PWM of the above embodiment
The operation of the full-bridge inverter will be described with reference to the time chart of FIG.

Now, a description will be given of a state where the current IO is flowing back to the reflux diode G4 and commutates from this state to the main switch element Q3.

When the auxiliary switch Qb is turned on by the drive circuit 24 (time T0), the current IL starts to flow through the reactor L3. The drive circuit 26 turns off the main switch element Q4 at a time T2 after a predetermined time has elapsed from the time T0.

When the main switch element Q4 is turned off, the resonance reactor L3 and the resonance capacitors C3 and C4 enter a resonance operation, and the output voltage VO increases. When the output voltage VO reaches the power supply voltage E (time T3), the return diode G3
Turns on.

By turning on the reflux diode G3,
The voltage between the emitter and the collector of the main switching element Q3 becomes zero volt, and the main switching element Q3 is turned on by the drive circuit 23 (time Tx), and zero voltage switching is performed.

The operations of the main switch elements Q1 and Q2 and the auxiliary switch Qa are the same as those described above, and an AC voltage can be obtained in the same manner as in the prior art.

According to this embodiment, only two auxiliary switching elements Qa and Qb having a large current rating are used. Further, a capacitor for dividing the DC power supply E into two is not required, and resonance occurs. Only one reactor L3 is used, and the auxiliary switches Qa and Q
Since the number of b is halved and the number of the drive circuits 21 to 26 and the number of independent power supplies for the drive circuits are reduced with this halving, the number of parts is greatly reduced and the cost is reduced. Further, as the number of auxiliary switches Qa and Qb is reduced by half, a radiator for the auxiliary switch becomes unnecessary or the radiator can be downsized. As a result, the size and cost of the partial resonance single-phase PWM full-bridge inverter can be significantly reduced.

[0024]

As described above, according to the present invention, the number of auxiliary switch elements and resonance reactors having a large current rating is reduced by half, and a capacitor for dividing the DC power supply into two is not required. Further, the number of auxiliary switches is reduced by half, and the number of drive circuits and independent power supplies for the drive circuits is reduced by the reduction of the number of auxiliary switches. Therefore, the number of parts is greatly reduced and the cost is reduced. Further, as the number of auxiliary switches is reduced by half, a radiator for the auxiliary switch becomes unnecessary, or the radiator can be reduced in size. As a result, the size and cost of the partial resonance single-phase PWM full-bridge inverter can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a specific configuration of a partial resonance single-phase PWM full-bridge inverter according to the present invention.

FIG. 2 is a time chart showing a part of the operation of the partial resonance single-phase PWM full-bridge inverter of FIG. 1;

FIG. 3 is a circuit diagram showing a specific configuration of a conventional partial resonance single-phase PWM full-bridge inverter.

FIG. 4 is a time chart showing a part of the operation of the conventional partial resonance single-phase PWM full-bridge inverter.

FIG. 5 is a time chart showing an operation of a conventional partial resonance single-phase PWM full-bridge inverter.

FIG. 6 is an explanatory diagram showing an AC voltage obtained by a partial resonance single-phase PWM full-bridge inverter.

[Explanation of symbols]

Q1 Main switch element (first main switch element) Q2 Main switch element (second main switch element) Q3 Main switch element (third main switch element) Q4 Main switch element (fourth main switch element) Qa First auxiliary switch Qb Second auxiliary switch G1 freewheeling diode (first freewheeling diode) G2 freewheeling diode (second freewheeling diode) G3 freewheeling diode (third freewheeling diode) G4 freewheeling diode (fourth freewheeling diode) C1 resonance capacitor (first resonance capacitor) C2 resonance capacitor (second resonance capacitor) C3 resonance capacitor (third resonance capacitor) C4 resonance capacitor (fourth resonance capacitor) L2 resonance reactor

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[Procedure amendment]

[Submission date] May 28, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

Claims (1)

[Claims] A first and a second main switch element connected between both terminals of a DC power supply and connected in series, and a third and a second main switch element connected between both terminals of the DC power supply and connected in series. Four main switch elements, a first freewheel diode and a first resonance capacitor connected in parallel to the first main switch element, a second freewheel diode and a second resonance capacitor connected in parallel to the second main switch element, Partial resonance single phase including a third freewheel diode and a third capacitor for resonance connected in parallel to the third main switch element, and a fourth freewheel diode and a fourth capacitor for resonance connected in parallel to the fourth main switch element A PWM full-bridge inverter, comprising: a first auxiliary switch and a resonance resistor between an intermediate connection point of the first and second main switch elements and an intermediate connection point of the third and fourth main switch elements. Vector and partial resonance single-phase PWM full-bridge inverter and a second auxiliary switch, characterized in that connected in series.