KR20120006930A - Resonant inverter device - Google Patents

Abstract

PURPOSE: A resonance type inverter apparatus is provided to suppress high frequency vibrations after turning off a second auxiliary switch, thereby reducing loss and expense by eliminating a snubber circuit. CONSTITUTION: A positive side input line(P) and a negative side input line(N) connect a voltage booster circuit(1) and an inverter circuit(3). An auxiliary circuit(2) is connected between the positive side input line and the negative side input line. The auxiliary circuit is comprised of auxiliary switches(Q1,Q2), a resonance reactor(Lr), and a diode. The inverter circuit outputs AC voltage to a filter circuit(4) by converting DC voltage into the AC voltage. A control circuit(10) switches main switches(S1-S4) by on/off controlling the auxiliary switch.

Description

Resonant Inverter Device {RESONANT INVERTER DEVICE}

The present invention relates to a resonant inverter device of soft switching control for converting direct current into alternating current.

As an example of a resonant inverter device, a power converter including a V-connected inverter circuit is known (Patent Document 1). The power converter includes first and second auxiliary switches, a resonance reactor, and a resonance capacitor, and turns on and off the first and second auxiliary switches to generate resonance by the resonance reactor and the resonance capacitor to turn on the main switch. By zero turn on (soft switching), the switching loss of the main switch is reduced.

In this power converter, snubber circuits are not provided in the first and second sub-switches, but practically, a snubber circuit is added between the collector and emitter of the first and second sub-switches. It is desirable to plan for overvoltage protection and suppression of high frequency vibration.

4 is a circuit diagram showing a resonant inverter device including a conventional snubber circuit. In Fig. 4, a booster circuit 1 is connected to both ends of a direct current power source E. As shown in Figs. The booster circuit 1 is a series circuit of a switch Qo composed of a booster reactor L1 connected to both ends of a DC power supply E and an insulated gate bipolar transistor IGBT, and a booster reactor L1 and a switch. It consists of the diode Dc which the anode was connected to the connection point of Qo, and boosts the voltage of the DC power supply E. The diode Do and the capacitor Co are connected in parallel between the collector-emitter of the switch Qo.

An auxiliary circuit 2a is connected to both ends of the booster circuit 1 via a positive input line P and a negative input line N. . The auxiliary circuit 2a is configured as follows. Between the positive input line P and the negative input line N, a series circuit of an auxiliary switch Q1 made of IGBT, an auxiliary capacitor Ca and an auxiliary capacitor Cb is connected. Between the connection point of the auxiliary capacitor Ca and the auxiliary capacitor Cb and the positive input line P, the series circuit of the auxiliary switch Q2 which consists of the resonance reactor Lr and IGBT is connected.

A diode Da is connected in parallel between the collector and emitter of the auxiliary switch Q1, and a series circuit of the snubber diode D5, the snubber capacitor C5, and the snubber capacitor C6 is connected. . The resistor R1 is connected to the connection point of the snubber diode D5 and the snubber capacitor C5 and one end of the auxiliary capacitor Cb. The resistor R2 is connected to the connection point of the snubber capacitor C5 and the snubber capacitor C6 and the connection point of the auxiliary capacitor Ca and the auxiliary capacitor Cb. The snubber diode D5, the snubber capacitors C5 and C6, and the resistors R1 and R2 constitute a snubber circuit of the auxiliary switch Q1.

A diode Db is connected in parallel between the collector and emitter of the auxiliary switch Q2, and a series circuit of the snubber capacitor C7 and the snubber capacitor C8 is connected. The snubber diode D6 is connected to the snubber capacitor C7 in parallel. The resistor R3 is connected to the connection point of the snubber capacitor C7 and the snubber capacitor C8 and the collector of the auxiliary switch Q1. The snubber diode D6, the snubber capacitors C7 and C8, and the resistor R3 constitute a snubber circuit of the auxiliary switch Q2.

The inverter circuit 3 is connected between the positive side input line P and the negative side input line N. FIG. In the inverter circuit 3, a series circuit (half bridge circuit) of the main switch S1 and the main switch S2 is provided between the positive side input line P and the negative side input line N. In addition, the series circuit (half bridge circuit) of the main switch S3 and the main switch S4 is connected. Diodes D1 to D4 and resonant capacitors C1 to C4 are connected between the collector and emitter of the main switches S1 to S4 made of IGBT.

The connection point of the main switch S1 and the main switch S2 is connected to the AC output terminal W1 through the reactor Lw, and the connection point of the main switch S3 and the main switch S4 is It is connected to the AC output terminal U1 via the reactor Lu, and the connection point of the auxiliary capacitor Ca and the auxiliary capacitor Cb is connected to the AC output terminal V1. The filter circuit 4 is composed of reactors Lu and Lw and condensers C11 and C12, and is a filter for removing high frequency components and outputting sinusoidal components. The control circuit 100 controls ON / OFF of each of the switches Qo, the auxiliary switches Q1 and Q2, and the main switches S1 to S4 to switch the main switches S1 to S4 at zero voltage, A sinusoidal three-phase AC voltage is output to the output terminals U1, V1, and W1.

Next, the operation will be described. First, the operation shown in FIG. 4 will be described with reference to the waveform diagram shown in FIG.

In Fig. 5, G (Q1) is the gate signal of the auxiliary switch Q1, G (Q2) is the gate signal of the auxiliary switch Q2, G (S3) is the gate signal of the main switch S3, and G (S4). ) Is the gate signal of the main switch S4, I (Lr) is the current flowing through the resonance reactor Lr, V (S3) is the voltage between the collector-emitter of the main switch S3, and I (S3) is the main switch. The collector current flowing through S3, V (S4), is the collector-emitter voltage of the main switch S4, and V (Q2) is the collector-emitter voltage of the auxiliary switch Q2.

In the period t2, when the auxiliary switch Q2 is turned on while the auxiliary switch Q1 is turned off, the charge of the resonant capacitor C3 is discharged to the path of C3? Lr? Q2? Cb? D4? C3. The current I (Lr) flows through the resonance reactor Lr. At this time, the current I (Lr) becomes a sinusoidal current due to the resonance of the resonance reactor Lr and the resonance capacitor C3.

In the period t3, when the discharge of the charge of the resonant capacitor C3 is completed, the voltage V (S3) of the resonant capacitor C3 becomes zero voltage and the current I (Lr) becomes zero. Turn on the main switch (S3). Accordingly, zero voltage switching of the main switch S3 can be realized.

In addition, the negative current I (Lr) starts to flow in the path of Cb → Db → Lr → S3 → C4 → Cb. The current I (Lr) and the current I (S3) become sinusoidal currents by the resonance of the resonance reactor Lr and the resonance capacitor C4.

In the period t4, the resonant capacitor C4 is charged by the resonant current to increase the voltage of V (S4). In the period t4, the auxiliary switch Q2 is turned off, but the resonant current flows through the diode Db.

If the current I (Lr) of the resonance reactor Lr rises to zero in the period t5 after the resonance is completed, the diode Db of the auxiliary switch Q2 at the start of the period t6. ) Is reverse recovery. The energy of this reverse recovery is accumulated in the resonance reactor Lr, but since there is no energy discharge path, a surge voltage is generated in the auxiliary switch Q2. After that, the parasitic capacitance of the auxiliary switch Q2 and the resonance of the resonance reactor Lr cause high frequency vibrations to the current I (Lr) of the resonance reactor Lr and the voltage V (Q2) of the auxiliary switch Q2. This happens. In the case where the switching of the auxiliary switch Q2 to off turns out after the period t6, the same phenomenon as the above phenomenon occurs because energy is accumulated in the resonance reactor Lr.

Next, the operation of the conventional resonant inverter device shown in FIG. 4 with the snubber circuit will be described with reference to the auxiliary circuit shown in FIG. 6 and the operation waveform diagram shown in FIG.

When there is a snubber circuit, the energy accumulated in the resonance reactor Lr flows through the snubber diodes D5 and D6 and snubber capacitors C5, C6, C7 and C8. The voltages of the snubber capacitors C5, C6, C7 and C8 are clamped to the auxiliary capacitors Ca and Cb through the resistors R1, R2 and R3. For this reason, in the period t6 of FIG. 7, it is possible to suppress the occurrence of high frequency vibration in the current I (Lr) of the resonance reactor Lr and the voltage V (Q2) of the auxiliary switch Q2. .

Japanese Patent Laid-Open No. 2004-260882

However, in the resonant inverter device shown in Fig. 4, since the snubber circuit is provided, the parts composed of diodes, capacitors and resistors are increasing. For this reason, there is a problem that the cost increases, the device becomes large, and a loss occurs due to the snubber circuit.

An object of the present invention is to provide a resonant inverter device that can reduce losses and costs and can be miniaturized.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention converts the DC voltage of the DC power supply supplied between the positive input line and the negative input line into an AC voltage, and outputs it. A resonant inverter device, comprising: a first series circuit connected between the positive input line and the negative input line, the first auxiliary circuit comprising a first auxiliary switch, a first auxiliary capacitor, and a second auxiliary capacitor; A second series circuit comprising a second auxiliary switch and a first diode connected between the first input line, the positive input line and the negative input line, and the first auxiliary capacitor. A resonance reactor connected between the connection point of the second auxiliary capacitor and the connection point of the second auxiliary switch and the first diode, and connected between the front input line and the negative input line, Cone It characterized in that it comprises a main switch (switch 主) formed by a series connection of two half-bridge circuit the inverter circuit (inverter 回路) obtained by connecting the (half bridge 回路) a plurality of parallel-connected parallel to the shelf.

According to the present invention, the voltage of the second auxiliary switch after the first auxiliary switch is turned on is clamped to the voltages of the first auxiliary capacitor and the second auxiliary capacitor by the forward current flowing through the first diode. Thereby, the high frequency vibration after turning off of a 2nd auxiliary switch can be suppressed. Therefore, the conventional snubber circuit can be reduced, and the loss and cost can be reduced, and the resonance type inverter device which can be miniaturized can be provided.

1 is a circuit diagram showing a resonant inverter device of Embodiment 1 of the present invention.
FIG. 2 is a diagram showing an auxiliary circuit provided in the resonant inverter device of Embodiment 1. FIG.
3 is an operational waveform diagram of each part of the resonant inverter device of Embodiment 1. FIG.
4 is a circuit diagram showing a resonant inverter device including a conventional snubber circuit.
5 is an operation waveform diagram of a resonant inverter device that does not include a conventional snubber circuit.
FIG. 6 is a view showing an auxiliary circuit provided in the conventional resonant inverter device shown in FIG.
7 is an operation waveform diagram of each part of the conventional resonant inverter device shown in FIG.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the resonance type inverter device of this invention is described in detail, referring drawings.

Example 1

1 is a circuit diagram showing a resonant inverter device of Embodiment 1 of the present invention. The resonant inverter device shown in FIG. 1 differs from the resonant inverter device shown in FIG. 4 only in the auxiliary circuit 2, and the rest of the structure is the same as that shown in FIG. Here, the configuration of the auxiliary circuit 2 will be mainly described.

Positive input line P and negative input line P connecting the booster circuit 1 and the inverter circuit 3 (inverter circuit) to each other. The auxiliary circuit 2 is connected between N). The auxiliary circuit 2 includes an auxiliary switch Q1 (first auxiliary switch), an auxiliary switch Q2 (second auxiliary switch), a resonance reactor Lr, an auxiliary capacitor Ca (first auxiliary capacitor), and an auxiliary switch. It consists of a capacitor Cb (second auxiliary capacitor) and a diode Ds (first diode).

Between the positive input line P and the negative input line N, an auxiliary switch Q1 made of IGBT, an auxiliary capacitor Ca, and a first series circuit composed of an auxiliary capacitor Cb are connected. The auxiliary switch Q1 is a switch for separating the front input line P and the auxiliary capacitor Ca. Auxiliary capacitor (Ca) and auxiliary capacitor (Cb) is composed of an electrolytic capacitor and has a large capacity.

In addition, between the positive side input line P and the negative side input line N, a second series circuit composed of an IGBT and an auxiliary switch Q2 serving as a resonance switch and a diode Ds is connected. The resonance reactor Lr is connected between the connection point of the auxiliary capacitor Ca and the auxiliary capacitor Cb, and the connection point of the auxiliary switch Q2 and the diode Ds. The diode Da is connected in parallel between the collector-emitter of the auxiliary switch Q1, and the diode Db is connected in parallel between the collector-emitter of the auxiliary switch Q2.

The inverter circuit 3 converts the DC voltage boosted by the booster circuit 1 supplied between the positive input line P and the negative input line N into an AC voltage to convert the filter circuit 4 into a filter voltage. ) Between the positive input line P and the negative input line N, a third series circuit comprising a main switch S1 (first main switch) and a main switch S2 (second main switch), and a main switch. A fourth series circuit composed of S3 (third main switch) and main switch S4 (fourth main switch) is connected.

Resonant capacitors C1 to C4 and diodes D1 to D4 are connected in parallel between the collector and emitter of the main switches S1 to S4, respectively. The resonant capacitors C1 to C4 may be parasitic capacitances of the main switches S1 to S4, and the diodes D1 to D4 may be parasitic diodes of the main switches S1 to S4.

The control circuit 10 controls on / off of the auxiliary switches Q1 and Q2 so that the voltages of the resonant capacitors C1 to C4 become zero voltages when the main switches S1 to S4 are turned on. Zero-switch the main switches S1 to S4.

Next, the operation of the resonant inverter device of Embodiment 1 thus constructed will be described with reference to the auxiliary circuit shown in FIG. 2 and the operation waveform diagram shown in FIG. In addition, the inverter circuit shown in Fig. 2 is a half bridge circuit of one arm (series connection of main switches S3 and S4), and each output current is represented by a current source Io. In addition, since the name of each part of the operation waveform in FIG. 3 is the same as the name of each part of the operation waveform shown in FIG. 5, description of these is abbreviate | omitted here.

In the first period t2, when the auxiliary switch Q1 is turned off while the auxiliary switch Q1 is turned off, the charge of the resonant capacitor C3 is discharged, and the path of C3? Q2? Lr? Cb? D4? C3 The current I (Lr) flows through the resonance reactor Lr. At this time, the current I (Lr) becomes a sinusoidal current due to the resonance of the resonance reactor Lr and the resonance capacitor C3.

In the period t3, when the discharge of the charge of the resonant capacitor C3 is completed, the voltage V (S3) of the resonant capacitor C3 becomes zero voltage and the current I (Lr) becomes zero. Turn on the main switch (S3). Accordingly, zero voltage switching of the main switch S3 can be realized.

In addition, the negative current I (Lr) starts to flow in the path of Cb → Lr → Q2 → S3 → C4 → Cb. The current I (Lr) and the current I (S3) become sinusoidal currents by the resonance of the resonance reactor Lr and the resonance capacitor C4.

In the period t4, the resonant capacitor C4 is charged by the resonant current, and the voltage of V (S4) is increased. In the period t4, the auxiliary switch Q2 is turned off but the resonant current flows through the diode Db.

The auxiliary switch Q1 is turned on at the end of the period t4, i.e., at the beginning of the period t5. When the current I (Lr) of the resonance reactor Lr rises to zero, the diode Db of the auxiliary switch Q2 reverse recovery at the beginning of the period t6. The energy accumulated in the resonance reactor Lr by the reverse recovery is regenerated to the auxiliary capacitor Cb in the path of Lr → Cb → Ds → Lr. In this period, the voltage V (Q2) of the auxiliary switch Q2 is clamped to the combined voltage of the auxiliary capacitors Ca and Cb. That is, the output voltage of the booster circuit 1 is clamped.

The energy accumulated in the resonator reactor Lr is regenerated in the auxiliary capacitor Cb so that in the period t6, the current I (Lr) of the resonator reactor Lr and the voltage V (Q2) of the auxiliary switch Q2. High frequency vibration of)) can be suppressed. The switching to the turn-off of the auxiliary switch Q2 is off after the period t6, so that even when energy is accumulated in the resonance reactor Lr, the same operation as described above is performed.

As described above, according to the resonant inverter device of the first embodiment, the voltage of the auxiliary switch Q2 after the auxiliary switch Q1 is turned on is such that the forward current of the diode Ds is resonant reactor Lr → auxiliary capacitor Cb. ¡Æ the diode Ds is driven by the resonant reactor Lr and clamped to the voltages of the auxiliary capacitor Ca and the auxiliary capacitor Cb. Thereby, the high frequency vibration after turning off auxiliary switch Q2 can be suppressed. Therefore, the conventional snubber circuit can be reduced.

In the conventional snubber circuit, a diode, a capacitor, and a resistor must be provided for each of the auxiliary switches Q1 and Q2. However, in Example 1, only the diode Ds is added, so that the loss and the cost can be greatly reduced. Can also downsize the device.

The present invention is not limited to the resonance type inverter device of the first embodiment. In the resonant inverter device of the first embodiment, the inverter circuit has been described in the V-wiring configuration, but the same applies to the single-phase bridge configuration or the three-phase bridge configuration.

The present invention can be applied to a DC-AC power converter or a grid-connected inverter device.

E: DC power
L1: Boost reactor
Qo: Switch
Q1, Q2: Auxiliary switch
S1 to S4: Main switch
Lr: Resonant Reactor
Da, Db, Dc, Ds, Do-D4: Diode
Ca, Cb: auxiliary capacitor
Co to C4: Resonant Capacitor
C11, C12: condenser
Lu, Lw: Reactor
1: boost circuit
2, 2a: auxiliary circuit
3: inverter circuit
4: filter circuit
10, 100: control circuit

Claims (3)

Resonant inverter device for converting DC voltage of DC power supplied from positive side input line and negative side input line into AC voltage and outputting it )as,
A first series circuit connected between the positive input line and the negative input line, the first auxiliary circuit comprising a first auxiliary switch, a first auxiliary capacitor, and a second auxiliary capacitor;
A second series circuit connected between the positive input line and the negative input line, the second serial circuit comprising a second auxiliary switch and a first diode;
A resonance reactor connected between a connection point of the first auxiliary capacitor and the second auxiliary capacitor and a connection point of the second auxiliary switch and the first diode,
A plurality of half bridge circuits connected in parallel are connected between the main input line and the sub input line and connected in series with two main switches connected in parallel with a resonant capacitor. The inverter circuit
Resonant inverter device characterized in that it comprises.
The method of claim 1,
After the first auxiliary switch is turned on, the voltage of the second auxiliary switch is clamped to the voltages of the first auxiliary capacitor and the second auxiliary capacitor by a forward current flowing through the first diode. Resonant inverter device characterized in that.
The method according to claim 1 or 2,
The inverter circuit formed by connecting two half-bridge circuits in parallel outputs a U phase and a W phase of a three-phase alternating current, and a connection point of the first auxiliary capacitor and the second auxiliary capacitor is a V phase of a three-phase alternating current. Resonant inverter device characterized in that the output.

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