JP2003230276A - Control method for power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for a power converter capable of preventing the generation of a spike voltage by a two-way switch and reducing loss induced by a reverse-leakage current. <P>SOLUTION: A step-down alternating current chopper circuit is constituted by using a first bidirectional switch SWa composed of two semiconductor switches Q1, Q2, and a second two-way switch SWb composed of two semiconductor switches Q3, Q4, for an alternating current power supply AC. The Q1, Q3 are turned on by a pulse-signal control circuit 21 all the time when the polarity of a power supply voltage of the alternating current power supply AC is positive, and alternately on/off-controlled at intervals of dead times wherein both the Q2, Q4 are simultaneously turned off. The Q2, Q4 are turned on all the time when the polarity of the power supply voltage is negative, and alternately on/off-controlled at intervals of dead times wherein both the Q1, Q3 are simultaneously turned off. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter control method using a bidirectional switch capable of turning on and off both currents.

[0002]

2. Description of the Related Art Conventionally, as a control method for a power conversion device of this type, a semiconductor bidirectional switch is constructed by connecting two self-extinguishing type semiconductor switches Q1 and Q2 having reverse breakdown voltage shown in FIG. 10 in antiparallel. (Hereinafter, simply referred to as a bidirectional switch) SWa, a bidirectional switch SWb similarly configured by connecting two self-arc-extinguishing semiconductor switches Q3 and Q4 in anti-parallel, and an AC power supply AC in a ring shape in series. connection,
A single-phase step-down AC chopper circuit is known in which a series circuit of a load circuit 11 and a reactor 12 is connected in parallel with a bidirectional switch SWb.

This single-phase step-down AC chopper circuit alternately turns on and off two bidirectional switches SWa and SWb to generate a load voltage, which is a voltage applied to a series circuit of a load circuit 11 and a reactor 12, as an AC power source. It can be adjusted to a voltage lower than the AC power supply voltage, and the load voltage value is 2
It is determined by the on / off ratio of the two switches SWa and SWb.

Both bidirectional switches SWa and SW
The semiconductor switches Q1, Q2 and Q3, Q4 of FIG.
On / off control is performed as shown in FIG. That is, the semiconductor switches Q1 and Q2 of the bidirectional switch SWa are turned on / off at the same time, the semiconductor switches Q3 and Q4 of the bidirectional switch SWb are turned on / off at the same time, the bidirectional switches SWa and SWb are turned on / off alternately, and the AC power supply AC In order to prevent a short circuit, a period A in which the bidirectional switches SWa and SWb are simultaneously turned off is provided.

Further, as a single-phase boost type chopper circuit,
As shown in FIG. 12, as in the case of FIG. 10, two bidirectional switches SWa and SWb are connected in series, a capacitor 13 is connected in parallel with these, and a load circuit 11 and a reactor 12 are connected in series with the capacitor 13. It is known that a circuit is connected and a series circuit of an AC power supply A and a boost reactor 14 is connected in parallel with the bidirectional switch SWa.

Also in this single-phase boost chopper circuit, the load voltage applied to the series circuit of the load circuit 11 and the reactor 12 is higher than the power supply voltage of the AC power supply AC by alternately turning on / off the bidirectional switches SWa and SWb. The voltage value of the load can be adjusted to the voltage and the two bidirectional switches SW
It is determined by the on / off ratio of a and SWb. Semiconductor switches Q1 and Q of these bidirectional switches SWa and SWb
The on / off control of 2 and Q3, Q4 is also performed in the same manner as in FIG. 11 described above, and in order to prevent the short circuit of the capacitor 13, a period A in which the bidirectional switches SWa and SWb are simultaneously turned off is provided.

Further, both the step-down type chopper circuit and the step-up type chopper circuit are constituted by bidirectional switches SWa and SWb.
Since the two semiconductor switches Q1, Q2 and Q3, Q4 are turned on and off at the same time, no voltage is applied to the gate of the semiconductor switch to which a reverse voltage is applied.

[0008]

However, in the case of the step-down chopper circuit described above, when the bidirectional switches SWa and SWb are turned off at the same time, the path of the inductive energy of the load circuit 11 is cut off, and the step-up chopper circuit. In the case of the circuit, when the bidirectional switches SWa and SWb are turned off at the same time, the path of the energy stored in the boost reactor 14 is cut off, and both of the step-down chopper circuit and the boost chopper circuit have the bidirectional switch SWa or SW
There is a problem that a spike voltage is generated in b and may be destroyed.

In order to solve this problem, conventionally, in order to suppress the spike voltage generated in the bidirectional switch SWa or SWb, for example, two diodes D1 and D2 connected in series as shown in FIG. In order to process the energy stored in the capacitor 15 of the AC snubber circuit, the AC snubber circuit in which D3 and D4 are connected in parallel and the capacitor 15 is connected in parallel with them are connected in parallel with the bidirectional switches SWa and SWb. In addition, a resistor is connected in parallel with the capacitor, or an inverter circuit composed of a semiconductor switch is connected in parallel with the capacitor to regenerate the power source, and the device becomes larger,
There is an unsolved problem that the manufacturing cost increases.

In addition, a paper "Proceeding" by M. Takei et al.
s of 2001 International Symposium on Power Semicon
ductor Devices & ICs, Osaka '', pp. 413-416,
As the characteristics of the self-extinguishing type semiconductor switch with reverse breakdown voltage,
It has been reported that, when a reverse voltage is applied to the switch, the reverse leakage current increases unless a voltage is applied to the gate, as shown in FIG. Therefore, in the case of the conventional control method, since no voltage is applied to the gate of the switch to which a reverse voltage is applied, there is an unsolved problem that the loss due to the reverse leakage current increases and the cooling device becomes large.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, and the AC snubber circuit can be omitted by preventing the generation of the spike voltage by the bidirectional switch. At the same time, it is an object of the present invention to provide a control method for a power converter that can reduce the loss due to reverse leakage current.

[0012]

In order to achieve the above object, the control method for a power converter according to a first aspect of the present invention is capable of independently turning on / off a current flowing in one direction and a current flowing in the other direction. In the control method of the power converter using the directional switch, to detect the voltage polarity of one of the load and the power supply, to ensure that a short circuit does not occur in the power supply while ensuring a path through which current flows according to the detected voltage polarity, The bidirectional switch is controlled to be turned on and off.

The power converter control method according to a second aspect of the present invention is the method of the first aspect, wherein the bidirectional switch is turned on / off by applying a reverse voltage among the semiconductor switches constituting the bidirectional switch. The feature is that a voltage is applied to the gate terminal of the semiconductor switch. Furthermore, the control method of the power converter according to claim 3 is such that the first and second bidirectional switches capable of independently turning on and off the current flowing in one direction and the current flowing in the other direction are connected in series with the power source. In a method of controlling a voltage conversion device in which a load circuit is connected in parallel with the second bidirectional switch, when the polarity of the power source is one direction, the first bidirectional switch causes the current to flow in both directions. Is turned on so that the second bidirectional switch is turned on only in one direction, and the first bidirectional switch is turned on so that a current flows only in the other direction. The second bidirectional switch is turned on so that current flows only in one direction, and the first bidirectional switch is turned on so that current flows only in the other direction. Switch in both directions And a third period for turning on so that a current flows, and when the polarity of the power source is in the other direction, the first bidirectional switch is turned on so that a current flows in both directions, and A fourth period in which the bidirectional switch is turned on so that current flows only in the other direction, and a first bidirectional switch is turned on so that current flows in only one direction, and the second bidirectional switch is turned on in the other direction. The fifth period of time when the current is turned on so that the current flows only in one direction, and the first bidirectional switch is turned on so that the current flows only in one direction, and the second bidirectional switch is turned on in both directions. And a sixth period for turning on so as to flow.

Furthermore, a control method for a power converter according to a fourth aspect of the present invention is characterized in that first and second bidirectional switches capable of independently turning on and off a current flowing in one direction and a current flowing in the other direction are used as power sources. Connect in series, connect a series circuit of a reactor and a power supply in parallel with the first bidirectional switch, and connect a parallel circuit of a capacitor and a load circuit in parallel with the series circuit of the first and second bidirectional switches. In the method of controlling a voltage converter described above, when the polarity of the capacitor is in one direction, the first bidirectional switch is turned on so that current flows in both directions, and the second bidirectional switch is turned on. First to turn on so that it flows only in the direction of
And a second period in which the first bidirectional switch is turned on so that current flows only in the other direction, and the second bidirectional switch is turned on so that current flows only in one direction. And a third period in which the first bidirectional switch is turned on so that current flows only in the other direction, and the second bidirectional switch is turned on so that current flows in both directions. A fourth time period in which the first bidirectional switch is turned on so that current flows in both directions and the second bidirectional switch is turned on so that current flows only in the other direction when in the other direction. Then, the first bidirectional switch is turned on so that the current flows only in one direction, and the second
And the first bidirectional switch is turned on so that the current flows only in one direction, and the second bidirectional switch is turned on. And a sixth period for turning on so that current flows in both directions.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a first embodiment when the present invention is applied to a single-phase step-down AC chopper circuit. In the first embodiment, the circuit configuration of the single-phase step-down AC chopper circuit has the same configuration as that of the above-described conventional example shown in FIG. 10, and the portions corresponding to those in FIG. Although the description is omitted, each semiconductor switch Q of the first and second bidirectional switches SWa and SWb
ON / OFF of 1, Q2 and Q3, Q4 is controlled by the control pulse generation circuit 20 as shown in FIG.

The control pulse generating circuit 20 detects the polarity of the power source voltage in the AC power source AC, and depending on the detected polarity, the first and second bidirectional switches S are as follows.
Wa and SWb semiconductor switches Q1, Q2 and Q
3, Q4 on / off is controlled. That is, AC power supply A
When the voltage polarity of C is positive, as shown in FIG. 2A, for example, the semiconductor switch Q1 and the second bidirectional switch in which the emitter of the first bidirectional switch SWa is connected to the AC power supply AC side. The semiconductor switch Q3 having the emitter of SWb connected to the first bidirectional switch SWa side is always on, and the collector of the first bidirectional switch SWa is connected to the AC power supply AC side. The first bidirectional switch SW is turned off at a time point t1 from the state where the semiconductor switch Q4 in which the collector of the directional switch SWb is connected to the first bidirectional switch SWa side is turned off.
The semiconductor switch Q2 of a is controlled to be in the ON state, this state is continued for a relatively long first period A, and then the semiconductor switch Q2 is returned to the OFF state at the time point t2. The semiconductor switch Q2 and the semiconductor switch Q4 of the second bidirectional switch SWb are both turned off, and this state becomes a relatively short dead time.
Then, the semiconductor switch Q4 of the second bidirectional switch SWb is controlled to be in the ON state at time t3 after continuing for the period B of
This state is continued for the third period C which is equal to the period A, and then the state is returned to the off state, and the first bidirectional switch S
Wa semiconductor switch Q2 and second bidirectional switch S
The semiconductor switches Q4 of Wb are both turned off, this state is continued for a second period D equal to the period B, then the process returns to the first period A, and the above periods A to D are repeated.

Here, the magnitude of the load voltage when the polarity of the power supply voltage is positive is determined by the magnitude of the on / off ratio of the semiconductor switches Q2 and Q4. In addition, the pulse control circuit 21, when the voltage polarity of the AC power supply AC is negative,
As shown in FIG. 2B, the first bidirectional switch SWa
Semiconductor switch Q2 and second bidirectional switch SWb
Of the semiconductor switch Q4 of the first bidirectional switch SWa and the semiconductor switch Q1 of the second bidirectional switch SWb of the semiconductor switch Q3 are both turned off at the time t11. The semiconductor switch Q1 of the switch SWa is controlled to be in the ON state, and this state is continued for a relatively long fourth period E, and then the time t
At step 12, the semiconductor switch Q1 is returned to the off state, and the semiconductor switch Q1 of the first bidirectional switch SWa and the semiconductor switch Q3 of the second bidirectional switch SWb are both turned off. Then, at time t13, the semiconductor switch Q3 of the second bidirectional switch SWb is controlled to be in the ON state, and this state is continued for the sixth period G equal to the period E. From the first bidirectional switch SWa to the off state to turn off both the semiconductor switch Q1 of the first bidirectional switch SWa and the semiconductor switch Q3 of the second bidirectional switch SWb, and this state is set to the fifth period H equal to the period F. After continuing for a while, the process returns to the fifth period E and the above periods E to H are repeated.

Here, the magnitude of the load voltage when the polarity of the power supply voltage is negative is determined by the magnitude of the on / off ratio of the semiconductor switches Q1 and Q3. Next, the operation of the first embodiment will be described. Now, the polarity of the power supply voltage in the AC power supply AC is positive as shown in FIG. 3A, and the control pulse generation circuit 20 causes the first period A in FIG.
In this state, the semiconductor switches Q1 and Q of the first bidirectional switch SWa are assumed to be controlled.
2 and the semiconductor switch Q3 of the second bidirectional switch SWb
Are in the ON state, and only the semiconductor switch Q4 of the second bidirectional switch SWb is in the OFF state. Therefore, the positive current output from the AC power supply AC is the first bidirectional switch S.
It returns to the AC power supply AC through the current path formed by the semiconductor switch Q2 of Wa, the load circuit 11, and the reactor 12.

From the first period A to the second period B, as shown in FIG. 3 (b), the first bidirectional switch S
By turning off the semiconductor switch Q2 of Wa, the supply of power from the AC power supply AC to the load circuit 11 is cut off. At this time, the second bidirectional switch SWb
Since the semiconductor switch Q3 of the load switch 11 is controlled to be always on, the inductive energy of the load circuit 11 is reduced to the semiconductor switch Q3.
Therefore, the spike voltage can be surely prevented.

After that, in the second period B to the third period C, as shown in FIG. 3C, the semiconductor switch Q4 of the second bidirectional switch SWb is turned on, but the first switch is turned on. Since the semiconductor switch Q2 of the bidirectional switch SWa is kept in the off state, the load circuit 1 is switched from the AC power supply AC.
Since the power supply to 1 is maintained in the cut-off state and both semiconductor switches Q3 and Q4 of the second bidirectional switch SWb are turned on, the load is supplied through the second bidirectional switch SWb as in the case of FIG. 3B. The inductive energy of the circuit 11 is processed.

Thereafter, when the period changes from the third period to the fourth period D, the semiconductor switch Q of the first bidirectional switch SWa.
The semiconductor switch Q of the second and second bidirectional switches SWb
Both 4 are turned off, and the inductive energy of the load circuit 11 is processed through the second bidirectional switch SWb as in the case of FIG. 3B. After that, the process returns to the first period A and the periods A to D are repeated when the polarity of the AC power supply AC continues to be positive.

After that, when the polarity of the AC power supply AC is inverted to negative, the semiconductor switch which is always on when the control pulse shown in FIG. 2B is output contrary to the above is the first bidirectional switch. SWa semiconductor switch Q2 and second
Is changed to the semiconductor switch Q4 of the bidirectional switch SWb, and the semiconductor switch Q1 of the first bidirectional switch SWa is changed.
And the semiconductor switch Q3 of the second bidirectional switch SWb
Is controlled to be turned on and off, a current flows through the current path formed by the AC power supply AC, the reactor 12, the load circuit 11, and the semiconductor switch Q1 of the first bidirectional switch SWa in the fifth section E, and the sixth period F to eighth period H
Then, the inductive energy of the load circuit 11 is processed through the second bidirectional switch SWb.

As described above, in the first embodiment, regardless of the voltage polarity of the AC power supply AC and the current polarity of the load circuit 11, the current path of the load circuit 11 is always secured and the AC power supply AC is short-circuited. Since the first bidirectional switch SWa and the second bidirectional switch SWb can be switched on and off so as not to occur, the first bidirectional switch SWa
Alternatively, the spike voltage generated in the second bidirectional switch SWb can be surely prevented, and the voltage can be applied to the gate of the semiconductor switch to which a reverse voltage is applied, so that the loss due to the reverse leakage current is significantly reduced. can do.

In the first embodiment, 2
The case where two semiconductor switches Q1, Q2 and Q3, Q4 are connected in parallel to form the bidirectional switches SWa and SWb has been described. However, the present invention is not limited to this, and as shown in FIG. The switches Qa and Qb are connected in series with their collectors connected to each other, and a diode Da is anti-parallel to both semiconductor switches Qa and Qb.
The first embodiment can also be applied to the case where the bidirectional switch is configured by connecting Db and Db.

In the first embodiment, the case where the present invention is applied to the single-phase step-down type AC chopper circuit has been described. However, the present invention is not limited to this, and FIG.
As shown in FIG. 3, a three-phase AC power supply A having U, V and W phases
A first bidirectional switch SWa _{1 and a} second bidirectional switch SWb ₁ are inserted in series between the U phase and the V phase of C, and similarly, the first bidirectional switch SWa ₂ and the second bidirectional switch SWa ₂ are connected between the W phase and the V phase. interposed the bidirectional switch SWb ₂ in series, the first bidirectional switch SWa ₁ and the second bidirectional switch SWb
_A Y connection is made between the connection point of _1, the connection point of the second bidirectional switch SWb ₁ and the second bidirectional switch SWb ₂ , and the connection point of the first bidirectional switch SWa ₂ and the second bidirectional switch SWb _2. Three-phase load 11a and reactor 12a
The present invention can also be applied to a three-phase step-down AC chopper circuit in which a series circuit of, a series circuit of the three-phase load 11b and the reactor 12b, and a series circuit of the three-phase load 11c and the reactor 12c are connected.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the present invention is applied to a single-phase boost type AC chopper circuit. That is, in the second embodiment, as shown in FIG. 6, the circuit configuration of the single-phase step-up AC chopper circuit has the same configuration as that of FIG. 12 of the above-described conventional example, and the portion corresponding to FIG. Although the same reference numerals are given and detailed description thereof is omitted, the control pulse generation circuit 21 controls ON / OFF of the semiconductor switches Q1, Q2 and Q3, Q4 of the first and second bidirectional switches SWa and SWb. .

In this control pulse generation circuit 21, the polarity of the terminal voltage of the capacitor 13 is detected, and the first and second bidirectional switches SWa are detected as follows according to the detected polarity.
And SWb semiconductor switches Q1, Q2 and Q3, Q
4 on / off is controlled. That is, when the terminal voltage polarity of the capacitor 13 is positive, as shown in FIG. 7A, for example, the semiconductor switch Q1 in which the emitter of the first bidirectional switch SWa is connected to the boost reactor 14 side.
And the semiconductor switch Q4 whose emitter of the second bidirectional switch SWb is connected to the capacitor 13 side are always on, and the collector of the first bidirectional switch SWa is connected to the boosting reactor 14 side. The collector of the second bidirectional switch SWb is the capacitor 1
At the time t1, the semiconductor switch Q2 of the first bidirectional switch SWa is controlled to be in the ON state from the state in which the semiconductor switches Q4 connected to the third side are both in the OFF state, and this state is maintained for a relatively long first period A only. After continuing, the semiconductor switch Q2 is returned to the off state at time t2, and both the semiconductor switch Q2 of the first bidirectional switch SWa and the semiconductor switch Q3 of the second bidirectional switch SWb are turned off. The semiconductor switch Q3 of the second bidirectional switch SWb is controlled to be in the ON state at the time t3 after continuing for the second period B having a relatively short dead time, and this state is maintained for the third period equal to the period A. After continuing only C, the state is returned to the off state, and the first bidirectional switch SWa
Semiconductor switch Q2 and second bidirectional switch SWb
Both semiconductor switches Q3 are turned off, this state is continued for a second period D equal to the period B, and then the first switch
Returning to the period A, the above periods A to D are repeated.

Here, the magnitude of the load voltage when the polarity of the power supply voltage is positive is determined by the magnitude of the on / off ratio of the semiconductor switches Q2 and Q3. In addition, when the terminal voltage polarity of the capacitor 13 is negative, the control pulse generation circuit 21 has the semiconductor switch Q2 of the first bidirectional switch SWa and the second bidirectional switch SWa as shown in FIG. 7B. The semiconductor switch Q3 of the switch SWb is always turned on, and the semiconductor switch Q1 of the first bidirectional switch SWa is turned on.
And the semiconductor switch Q4 of the second bidirectional switch SWb
The semiconductor switch Q1 of the first bidirectional switch SWa is controlled to be in the on state at a time t11 from the state where both are turned off, and this state is continued for a relatively long fourth period E, and then at the time t12. By returning Q1 to the off state, both the semiconductor switch Q1 of the first bidirectional switch SWa and the semiconductor switch Q4 of the second bidirectional switch SWb are turned off, and this state becomes a relatively short dead time. From the time point t13
Then, the semiconductor switch Q4 of the second bidirectional switch SWb is controlled to the ON state, and this state is equal to the period E
For a period G, and then returned to the off state,
Bidirectional switch SWa of semiconductor switch Q1 and second
Both the semiconductor switches Q4 of the bidirectional switch SWb are turned off, this state is continued for the fifth period H which is equal to the period F, and then the period returns to the fifth period E, and the above periods E to H are repeated.

Here, the magnitude of the load voltage when the polarity of the power supply voltage is negative is determined by the magnitude of the on / off ratio of the semiconductor switches Q1 and Q4. Next, the operation of the second embodiment will be described. Now, as shown in FIG.
The polarity of the power supply voltage of the AC power supply AC is positive, and the polarity of the capacitor 13 is the second bidirectional switch S as shown by the arrow.
It is assumed that the Wa side is positive. When the semiconductor switch Q2 of the first bidirectional switch SWa is turned on by controlling the period A in this state, the AC power supply AC passes through the boost reactor 14 and the semiconductor switch Q2 of the first bidirectional switch SWa. Energy is stored in the boost reactor 14 by being short-circuited. At this time,
Since the semiconductor switch Q3 of the second bidirectional switch SWb is in the off state, the short circuit of the capacitor 13 is not formed, and the charging energy of the capacitor is changed to the load circuit 11.
And to the reactor 12.

From the period A to the period B, FIG.
As shown in (b), since the semiconductor switch Q2 of the first bidirectional switch SWa is turned off, the short-circuit path of the AC power supply AC is eliminated, so that the power supply voltage of the AC power supply AC and the boosting reactor 14 are increased. The sum of the stored energy is applied to the capacitor 13. After that, in the period B to the period C, as shown in FIG. 8C, the semiconductor switch Q3 of the second bidirectional switch SWb is controlled to be in the ON state, so that the power supply voltage and the boosting reactor 14 are accumulated. The state where the sum of energy is applied to the capacitor 13 is continued.

After that, when the period C is changed to the period D, the first
Bidirectional switch SWa of semiconductor switch Q2 and second
Since the semiconductor switch Q3 of the bidirectional switch SWb is turned off, the state shown in FIG. 8B is established, and the state in which the sum of the power supply voltage and the energy stored in the boosting reactor 14 is applied to the capacitor 13 is continued. It After that, by returning from the period D to the period A, as shown in FIG. 8A, the energy is accumulated in the boosting reactor 14, and the above operation is repeated thereafter.

On the other hand, when the polarity of the power source voltage of the AC power source AC is inverted to the negative polarity, the polarity of the capacitor 13 becomes opposite to that shown in FIG. 5, and the semiconductor switch Q1 of the first bidirectional switch SWa is turned on in the period E. As a result, the semiconductor switch Q1 and the boosting reactor 14 shown in FIG.
By forming a short circuit of the AC power supply AC opposite to that in (a), energy is accumulated in the boosting reactor 14, and the semiconductor switch Q1 is turned off in the period F thereafter. Even if the reverse current path is formed and then the semiconductor switch Q4 of the second bidirectional switch SWb is turned on in the period G, the current path opposite to that in FIG. When the switch Q4 returns to the off state, the current path opposite to that in FIG. 8B is maintained.

Therefore, in the second embodiment as well, the bidirectional switch SWa is provided so as to prevent the short circuit of the capacitor 13 while always ensuring the power supply current path regardless of the AC power supply AC current polarity and the voltage polarity of the capacitor 13. And SWb
Can be switched on and off, and the boost reactor 14
The path of the energy stored in the switch is not interrupted, it is possible to reliably prevent the spike voltage from being generated in the bidirectional switch SWa or SWb, and the voltage is applied to the gate of the semiconductor switch to which a reverse voltage is applied. Therefore, it is possible to significantly reduce the loss due to the reverse leakage current.

In the second embodiment, the bidirectional switches SWa and Sa are also used as in the first embodiment.
Wb can be replaced with the configuration shown in FIG. Also,
In the second embodiment, the case where the present invention is applied to the single-phase step-up AC chopper circuit has been described, but the present invention is not limited to this, and as shown in FIG. Phase-up reactors 14a, 14b and 14c are connected to the V-phase, the V-phase and the W-phase, respectively, a capacitor 13a is connected between the U-phase and the V-phase, a capacitor 13b is connected between the V-phase and the W-phase, and a capacitor 13c is connected between the W-phase and the U-phase. The first bidirectional switch SWa ₁ is connected between the boost reactors 14a and 14b.
second bidirectional switch SW between the capacitor a and the capacitor 13a
b ₁ is inserted, the first bidirectional switch SWa ₂ is connected between the boost reactors 14b and 14c, and the second bidirectional switch SWb ₂ is inserted between the boost reactor 14c and the capacitor 13b. And 1
A series circuit of a three-phase load 11a and a reactor 12a, a series circuit of a three-phase load 11b and a reactor 12b, and a three-phase load 11c and a reactor 1 which are Y-connected between connection points of 3c.
The present invention can be applied to a three-phase boost type AC chopper circuit in which a 2c series circuit is connected.

[0035]

As described above, according to the inventions of claims 1 to 4, the bidirectional switch constituting the power conversion device ensures the flow path of the current and does not short the power supply or the capacitor. Since the AC snubber circuit, which was conventionally indispensable, can be omitted, the power converter can be downsized and the manufacturing cost can be reduced. To be

Further, since a voltage can be applied to the gate of the semiconductor switch to which a reverse voltage is applied, reverse leakage current can be reduced and loss can be reduced, so that the cooling device can be downsized. can get.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment when the present invention is applied to a single-phase step-down AC chopper circuit.

FIG. 2 is a waveform diagram showing a pulse signal supplied to each semiconductor switch of the bidirectional switch according to the first embodiment.

FIG. 3 is an operation explanatory diagram of the first embodiment.

FIG. 4 is a circuit diagram showing another configuration of the bidirectional switch.

FIG. 5 is a circuit diagram showing a three-phase step-down AC chopper circuit to which the first embodiment can be applied.

FIG. 6 is a circuit diagram showing a second embodiment when the present invention is applied to a single-phase boost type AC chopper circuit.

FIG. 7 is a waveform diagram showing a pulse signal supplied to each semiconductor switch of the bidirectional switch according to the second embodiment.

FIG. 8 is an operation explanatory diagram of the second embodiment.

FIG. 9 is a circuit diagram showing a three-phase boost AC chopper circuit to which the second embodiment can be applied.

FIG. 10 is a circuit diagram showing a conventional single-phase step-down AC chopper circuit.

FIG. 11 is a waveform diagram showing a pulse signal supplied to a bidirectional switch of a conventional single-phase step-down AC chopper circuit.

FIG. 12 is a circuit diagram showing a conventional single-phase step-up AC chopper circuit.

FIG. 13 is a circuit diagram showing an AC snubber circuit.

FIG. 14 is a characteristic diagram showing a reverse voltage leakage current characteristic.

[Explanation of symbols]

AC AC power supply SWa First bidirectional switch SWb Second bidirectional switch Q1 to Q4 semiconductor switches 11 load circuit 12 reactor 13, 13a to 13c capacitors 14,14a-14c Boosting reactor 21 Pulse signal control circuit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5H750 BA05 CC06 DD26 DD27 FF05                       FF06 GG02                 5J055 AX22 AX54 AX63 BX16 CX08                       CX14 DX04 DX74 DX83 EX06                       EY07 EY17 FX10 FX12 GX01                       GX04 GX06

Claims (4)

[Claims] 1. A method of controlling a power conversion device using a bidirectional switch capable of independently turning on and off a current flowing in one direction and a current flowing in the other direction, detecting one of a voltage polarity of a load and a power supply, A method of controlling a power conversion device, comprising performing on / off control of the bidirectional switch so that a short circuit does not occur in the power source while ensuring a path through which a current flows according to the detected voltage polarity. 2. On / off control of the bidirectional switch,
The method of controlling a power conversion device according to claim 1, wherein a voltage is applied to a gate terminal of a semiconductor switch to which a reverse voltage is applied among the semiconductor switches forming the bidirectional switch. 3. A first and a second bidirectional switch capable of independently turning on and off a current flowing in one direction and a current flowing in the other direction are connected in series to a power source, and are parallel to the second bidirectional switch. In a method of controlling a voltage converter in which a load circuit is connected to the first power switch, the first bidirectional switch is turned on so that current flows in both directions when the power supply has one polarity, and A first period in which the bidirectional switch is turned on so as to flow only in one direction, and a first bidirectional switch is turned on so that current flows only in the other direction, and the second bidirectional switch is turned in one direction. The second period in which the current is turned on so that only the current flows, and the first bidirectional switch is turned on so that the current flows only in the other direction, and the second bidirectional switch is turned on so that the current flows in both directions. Third period to turn on Preparative provided, when the polarity of the power supply is the other direction, turns on so that current flows through the first bidirectional switch in both directions,
A fourth period in which the second bidirectional switch is turned on so that current flows only in the other direction, and a first bidirectional switch is turned on so that current flows in only one direction, and the second bidirectional switch is turned on. A fifth period in which the switch is turned on so that current flows only in the other direction, and a first bidirectional switch is turned on so that current flows only in one direction and the second bidirectional switch is turned in both directions. And a sixth period during which the power is turned on so that a current flows through the power converter. 4. A first and a second bidirectional switch capable of independently turning on and off a current flowing in one direction and a current flowing in the other direction are connected in series to a power source, and are connected in parallel with the first bidirectional switch. In the control method of the voltage converter, in which a series circuit of a reactor and a power supply is connected to a parallel circuit of a capacitor and a load circuit in parallel with the series circuit of the first and second bidirectional switches, the polarity of the capacitor is If there is one direction,
A first period in which the first bidirectional switch is turned on so that current flows in both directions, and the second bidirectional switch is turned on so that current flows only in one direction; Turn on so that current flows only in the direction of
And the first bidirectional switch is turned on so that a current flows only in one direction, and the second bidirectional switch is turned on so that a current flows only in one direction. And a third period in which the capacitor is turned on so that current flows in both directions, and when the polarity of the capacitor is the other direction, the first
The second bidirectional switch is turned on so that current flows in both directions, and the second bidirectional switch is turned on so that current flows only in the other direction. And a second bidirectional switch is turned on so that current flows only in the other direction, and a first bidirectional switch is turned on only in one direction. And a sixth period in which the second bidirectional switch is turned on so that current flows in both directions.