JP2020072540A - Power conversion device - Google Patents

Abstract

To provide a power conversion device realizing miniaturization owing to one control power source capable of constituting all control power sources of other semiconductor switches.SOLUTION: A power conversion device comprises a bidirectional semiconductor switch 1401 constituted by being serially connected with a first semiconductor switch 1001 connected with DC low voltage and a second semiconductor switch 1101 connected with DC high voltage, and by being serially connected with a third semiconductor switch 1201 connected with a pseudo AC output terminal and a fourth semiconductor switch 1301 connected with a DC midpoint between high voltage and low voltage. In the power conversion device, a positive electrode of a control power source 1003 and a positive electrode of a capacitor 1103 for a semiconductor switch are connected with each other via the capacitor for the semiconductor switch and a first resistor 1112, and a positive electrode of the control power source 1003 and a positive electrode of a capacitor 1203 for the bidirectional semiconductor switch are connected with each other via a second diode 1211 and a second resistor 1212.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion device.

  Conventionally, this type of power conversion device, in the operation as an inverter, is converted into a pseudo alternating current by rapidly turning on and off a semiconductor switch in which a diode element is connected in antiparallel to a unidirectional semiconductor switching element, and is converted into a pseudo alternating current. The AC motor is driven at a variable speed by the pseudo AC.

  In particular, when the semiconductor switch is turned on and off, the potential of the circuit suddenly changes, causing large noise and large switching loss.Therefore, a neutral point of the DC potential of the DC power part is provided. There is an inverter circuit system called a so-called three-level inverter that turns on and off between a neutral point and a direct current low voltage line, or between a neutral point and a direct current low voltage line.

  On the other hand, a system that uses only a DC high voltage line and a DC low voltage line without using a neutral point is called a two-level inverter.

  In the three-level inverter circuit, the AC-side output terminal has a potential of either a DC high-voltage line, a DC neutral point, or a DC low-voltage line, so a semiconductor switch connected to each potential is required. ..

  In particular, since the current output from the neutral point is bidirectional, a bidirectional semiconductor switch is required. In order to create a three-phase pseudo alternating current, at least nine semiconductor switches are required for the three-level inverter, whereas the two-level inverter has six semiconductor switches.

  These semiconductor switches can be turned on by applying a certain electric potential to one end of the semiconductor switch, but in order to give a certain electric potential, a small but independent power supply ( Hereinafter, it will be referred to as a control power supply).

  Further, since the three-level inverter has a large number of semiconductor switches, the number of independent control power sources also increases.

  On the other hand, a semiconductor switch composed of a unidirectional semiconductor switch element and a diode element connected in antiparallel to the unidirectional semiconductor switch element is connected in series and connected to a high voltage line and a low voltage line of DC. , A control power supply for a three-level inverter circuit in which the same semiconductor switch is serially connected in reverse polarity to the output terminal of a two-level inverter that outputs the midpoint of the AC to the neutral point of the DC. As a method of reducing the number of the two, when the cathodes of the diode elements of the semiconductor switches that form the bidirectional switch are connected in common, the number of independent control power supplies can be realized by two, or the bidirectional switch is configured. Disclosed is a method in which the number of independent control power supplies can be realized when the anodes of the diode elements of the semiconductor switches are commonly connected. Is (e.g., see Patent Document 1).

JP, 2011-61883, A

  However, the conventional configuration requires a plurality of independent control power supplies and a plurality of output windings of the insulation transformer, which makes it difficult to downsize the conversion device. Was.

  The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a power conversion device that realizes miniaturization of the device, since one control power supply can configure all the control power supplies of other semiconductor switches. It is what

  In order to solve the conventional problems, the power conversion device of the present invention includes a plurality of semiconductor switches each including a unidirectional semiconductor switch element and a diode element connected in antiparallel to the unidirectional semiconductor switch element. Comprising, one end of the first semiconductor switch and one end of the second semiconductor switch are connected in series, the other end of the first semiconductor switch is connected to a direct current low voltage line, The other end is connected to a direct current high voltage line, and a connection line between the first semiconductor switch and the second semiconductor switch is provided with an output terminal of a two-level inverter that generates a pseudo alternating current potential. And one end of the third semiconductor switch and one end of the fourth semiconductor switch are connected in series so that the anode of the diode element is common, The other end of the body switch is connected to the output terminal, and the other end of the fourth semiconductor switch is formed by being connected to a DC neutral point between the high voltage line and the low voltage line. A bidirectional semiconductor switch, a control power supply connected to the low voltage line, a semiconductor switch capacitor connected to a connection line between the second semiconductor switch and the output terminal, and a potential of the anode. A bidirectional semiconductor switch capacitor provided as a reference, and the positive electrode of the control power supply and the positive electrode of the control power supply capacitor for the semiconductor switch have a first diode and a first resistor. And the positive electrode of the control power supply and the positive electrode of the bidirectional semiconductor switch capacitor are connected via a second diode and a second resistor. It has been.

  Thus, by turning on the first semiconductor switch, from the positive electrode of the control power supply connected to the low voltage line, through the second diode and the second resistor, the bidirectional semiconductor switch capacitor, the third For the anti-parallel diode element of the semiconductor switch, the first semiconductor switch, and the negative electrode of the control power source, a current flows, so at this time, for the bidirectional semiconductor switch connected in parallel with the third control circuit for the bidirectional semiconductor switch. The capacitor is charged to temporarily form a control power supply for the bidirectional semiconductor switch.

  Further, by turning on the first semiconductor switch, from the positive electrode of the control power supply connected to the low voltage line, via the first diode and the first resistor, the control power supply capacitor for the semiconductor switch, Since a current flows through the first semiconductor switch and the negative electrode of the control power supply, at this time, the semiconductor switch capacitor connected in parallel with the second control circuit for the second semiconductor switch is charged and temporarily A control power supply for the second semiconductor switch is configured.

  That is, since the control power supply for the bidirectional semiconductor switch and the control power supply for the second semiconductor switch can be configured from the control power supply connected to the DC low voltage line, the device can be downsized. A power converter can be provided.

  According to the present invention, since one control power supply can configure all the control power supplies for the other semiconductor switches, it is possible to provide a power conversion device that realizes miniaturization of the device.

Circuit block diagram of a power conversion device according to Embodiment 1 of the present invention Circuit block diagram showing the operation of the control power supply in the power converter Circuit block diagram showing the operation of the control power supply in another power converter

  A first invention comprises a plurality of semiconductor switches each composed of a unidirectional semiconductor switching element and a diode element connected in antiparallel to the unidirectional semiconductor switching element, wherein one end of the first semiconductor switch and a second semiconductor switch are provided. One end of the semiconductor switch is connected in series, the other end of the first semiconductor switch is connected to a DC low voltage line, and the other end of the second semiconductor switch is connected to a DC high voltage line. An output terminal of a two-level inverter that generates a pseudo AC potential is provided on a connection line between the first semiconductor switch and the second semiconductor switch, and one end of the third semiconductor switch and the fourth semiconductor switch are provided. One end of the semiconductor switch is connected in series so that the anode of the diode element is common, and the other end of the third semiconductor switch is connected to the output terminal. The other end of the fourth semiconductor switch is connected to the low voltage line and a bidirectional semiconductor switch formed by being connected to a DC neutral point between the high voltage line and the low voltage line. A control power supply, a semiconductor switch capacitor connected to a connection line between the second semiconductor switch and the output terminal, and a bidirectional semiconductor switch capacitor provided with reference to the potential of the anode. And a positive electrode of the control power supply and a positive electrode of the control power supply capacitor for the semiconductor switch are connected via a first diode and a first resistor, and the positive electrode of the control power supply is And the positive electrode of the bidirectional semiconductor switch capacitor is a power conversion device connected via a second diode and a second resistor.

  Thus, by turning on the first semiconductor switch, from the positive electrode of the control power supply connected to the low voltage line, through the second diode and the second resistor, the bidirectional semiconductor switch capacitor, the third For the anti-parallel diode element of the semiconductor switch, the first semiconductor switch, and the negative electrode of the control power source, a current flows, so at this time, for the bidirectional semiconductor switch connected in parallel with the third control circuit for the bidirectional semiconductor switch. The capacitor is charged to temporarily form a control power supply for the bidirectional semiconductor switch.

  Further, by turning on the first semiconductor switch, from the positive electrode of the control power supply connected to the low voltage line, via the first diode and the first resistor, the control power supply capacitor for the semiconductor switch, Since a current flows through the first semiconductor switch and the negative electrode of the control power supply, at this time, the semiconductor switch capacitor connected in parallel with the second control circuit for the second semiconductor switch is charged and temporarily A control power supply for the second semiconductor switch is configured.

  That is, since the control power supply for the bidirectional semiconductor switch and the control power supply for the second semiconductor switch can be configured from the control power supply connected to the DC low voltage line, the device can be downsized. A power converter can be provided.

  A second invention is, in particular, in the first invention, the third semiconductor switch and the fourth semiconductor switch are MOSFETs, and the diodes forming the third semiconductor switch and the fourth semiconductor switch. The element is a parasitic diode of MOSFET.

  As a result, the conduction characteristic of the MOSFET is close to that of a resistor, so that the voltage drop is smaller than that of a diode near the zero cross in AC input / output, and the bidirectional semiconductor switch capacitor is charged to control the bidirectional semiconductor switch control power supply. Since the voltage of the control power supply for the bidirectional semiconductor switch can be increased in forming the above, the circuit loss of the power conversion device can be reduced.

  A third invention is characterized in that, in the first or second invention, the third semiconductor switch is turned on while the second semiconductor switch is turned off.

  As a result, when the potential between the low voltage and the neutral point is generated by the complementary ON / OFF of the first semiconductor switch and the bidirectional semiconductor switch, the fourth semiconductor switch connected to the neutral point. And the first semiconductor switch are complementarily turned ON / OFF.

  At this time, even if the third semiconductor switch is in the OFF state, the connection is maintained via the diode in parallel, so that the fourth semiconductor switch and the first semiconductor switch connected to the neutral point are connected to each other. It is possible to generate the potential between the low voltage and the neutral point only by complementary ON / OFF of.

  Furthermore, by turning on the third semiconductor switch, the connection via the diode becomes the connection via the channel of the MOSFET, and the voltage drop can be made smaller than the connection via the diode. Therefore, the voltage drop in the charging path from the control power supply connected to the low voltage line is reduced, and the degree of freedom in designing the control circuit for driving the semiconductor switch is improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment.

(Embodiment 1)
FIG. 1 is a circuit block diagram of a power conversion device according to a first embodiment of the present invention.

  In FIG. 1, the first semiconductor switch 1001 is composed of a unidirectional semiconductor switch element 1001a and a diode element 1001b connected in antiparallel to the unidirectional semiconductor switch element 1001a.

  A plurality of semiconductor switches that perform the same function as the first semiconductor switch 1001 are provided in addition to the second semiconductor switch 1101, the third semiconductor switch 1201, and the fourth semiconductor switch 1301.

  A direct current power supply is formed by connecting a direct current low voltage side capacitor 1010 and a direct current high voltage side capacitor 1110 in series, and the first semiconductor switch 1001 is provided on the direct current low voltage line and the second semiconductor is provided on the direct current high voltage line. The switch 1101 is connected.

  The other terminals of the first semiconductor switch 1001 and the second semiconductor switch 1101 are both connected to the pseudo AC line, and the connection point is the output terminal of the two-level inverter having the pseudo AC terminal.

  Further, the connection point of the DC low-voltage side capacitor 1010 and the DC high-voltage side capacitor 1110 is a DC neutral point, and is a pseudo AC terminal via the series connection of the fourth semiconductor switch 1301 and the third semiconductor switch 1201. It is connected to the pseudo AC line which is the output terminal of the two-level inverter.

  Here, if the first semiconductor switch 1001 is turned ON, the potential of the pseudo AC line becomes the same potential as that of the DC low voltage line, and if the second semiconductor switch 1101 is turned ON, the potential of the pseudo AC line becomes. When the third semiconductor switch 1201 and the fourth semiconductor switch 1301 are turned on, the pseudo AC line has the same potential as the DC high voltage line, and the pseudo AC line has the same potential as the DC neutral point.

  By appropriately switching this, a pseudo AC potential can be generated from the pseudo AC line.

  Further, the DC low voltage line is provided with a control power supply 1003 for the first semiconductor switch 1001, and the control power supply 1003 serves as a power supply for the first control circuit 1002 of the first semiconductor switch 1001. This makes it possible to control ON / OFF of the first semiconductor switch 1001 (note that the control command terminal of the first control circuit 1002 is omitted).

  Further, the positive terminal of the control power supply 1003 is connected to the semiconductor switch capacitor 1103 via the first diode 1111 and the first resistor 1112.

  The positive terminal of the control power supply 1003 is connected to the bidirectional semiconductor switch capacitor 1203 via the second diode 1211 and the second resistor 1212.

  One end of the semiconductor switch capacitor 1103 is connected to the pseudo AC line, and the other end of the semiconductor switch capacitor 1103 is connected to the power supply terminal of the second control circuit 1102 of the second semiconductor switch 1101.

  Similarly, both ends of the bidirectional semiconductor switch capacitor 1203 are connected to the power supply terminal of the third control circuit 1202 of the third semiconductor switch 1201 and the power supply terminal of the fourth control circuit 1302 of the fourth semiconductor switch 1301. , Connected in parallel.

  That is, if the semiconductor switch capacitor 1103 and the bidirectional semiconductor switch capacitor 1203 can be charged by some method, the second semiconductor switch 1101, the third semiconductor switch 1201, and the fourth semiconductor switch 1301 are driven and controlled. It is configured to be able to.

  The principle of operation will be described with reference to FIG. FIG. 2 additionally shows charging paths to the semiconductor switch capacitor 1103 and the bidirectional semiconductor switch capacitor 1203 based on the circuit of FIG.

  The first semiconductor switch 1001 is turned on by the control power supply 1003 and the first control circuit 1002 provided on the DC low voltage line. By turning on the first semiconductor switch 1001, the voltage of the pseudo AC line becomes almost the same potential as the DC low voltage line, that is, the lowest potential in this circuit.

  At this time, the bidirectional semiconductor switch capacitor from the control power supply 1003 via the second diode 1211, the second resistor 1212, the diode element 1201a of the third semiconductor switch 1201 and the first semiconductor switch 1001. 1203 is charged.

  Since the bidirectional semiconductor switch capacitor 1203 is charged, a power source for driving the third control circuit 1202 of the third semiconductor switch 1201 and the fourth control circuit 1302 of the fourth semiconductor switch 1301 is temporarily formed. Will be.

  Similarly, the semiconductor switch capacitor 1103 is charged from the control power supply 1003 via the first diode 1111, the first resistor 1112, and the first semiconductor switch 1001.

  Since the semiconductor switch capacitor 1103 is charged, the power supply for driving the second control circuit 1102 for the second semiconductor switch 1101 is temporarily formed.

  That is, as long as electric charge is stored in the semiconductor switch capacitor 1103 and the bidirectional semiconductor switch capacitor 1203, the second semiconductor switch 1101, the third semiconductor switch 1201, and the fourth semiconductor switch 1301 can be drive-controlled.

  To generate the pseudo AC, the first semiconductor switch 1001 is frequently turned ON, and the control power supply 1003 provided on the DC low voltage line can be commonly used for other pseudo AC lines.

  As described above, according to the power conversion device in the first embodiment of the present invention, it is possible to form all the control power supplies in the power conversion device for multi-phase pseudo alternating current from one control power supply 1003. is there.

  As shown in FIGS. 1 and 2, it is desirable that the third semiconductor switch 1201 and the fourth semiconductor switch 1301 that form the bidirectional semiconductor switch 1401 be formed of MOSFETs.

  This is because when the MOSFET is on, the passage loss characteristic becomes a resistance characteristic, and when the current is small, the voltage drop can be reduced.

  Further, the diode element 1201b forming the third semiconductor switch 1201 and the diode element 1301b forming the fourth semiconductor switch 1301 are preferably parasitic diodes of MOSFET.

  The operation during the operation will be described based on FIG.

  The second semiconductor switch 1101 is OFF, and the bidirectional semiconductor switch 1401 (the third semiconductor switch 1201 and the fourth semiconductor switch 1301) is complementary ON / OFF of the first semiconductor switch 1001. The case where a voltage between a point potential and a low voltage is generated is shown.

  Here, even if the third semiconductor switch 1201 is turned on, a short circuit between the neutral point and the low voltage line does not occur unless the fourth semiconductor switch 1301 and the first semiconductor switch 1001 are turned on at the same time. ..

  Therefore, the third semiconductor switch 1201 may be turned on and the fourth semiconductor switch 1301 and the first semiconductor switch 1001 may be turned on / off complementarily.

  At this time, the current flowing from the pseudo AC terminal to the outside is an AC current, and the first semiconductor switch 1001 and the bidirectional semiconductor switch 1401 (the third semiconductor switch 1201 and the fourth semiconductor switch 1301) are time-divided. Flowing.

  With an alternating current, the amount of current is small before and after the current polarity is reversed, and the voltage drop in the MOSFET is small.

  Therefore, the voltage drop of the system connected to the control power supply 1003 of the first semiconductor switch 1001 on the low voltage side becomes small, and the control of the bidirectional semiconductor switch 1401 (the third semiconductor switch 1201 and the fourth semiconductor switch 1301) is controlled. The voltage drop in the bidirectional semiconductor switch capacitor 1203 forming the power supply is alleviated, and the degree of freedom in designing the drive circuit of the bidirectional semiconductor switch 1401 (the third semiconductor switch 1201 and the fourth semiconductor switch 1301) is improved.

  Furthermore, as can be understood from what has been described so far, when the first semiconductor switch 1001 on the low voltage side is ON, the pseudo AC line is on the DC low potential side.

  Therefore, when configuring a three-phase circuit for driving a three-phase motor, if the semiconductor switches on the low voltage side of the three phases are turned on at the same time before driving, each drive power source can be operated without affecting the motor. Can be configured.

  Also, when used in a three-phase rectifier circuit, it is equivalent to turning on by a diode in anti-parallel without turning on the semiconductor switch on the low voltage side of the lowest potential of the three pseudo AC lines. Therefore, charging from the control power supply 1003 to the semiconductor switch capacitor 1103 and the bidirectional semiconductor switch capacitor 1203 can be realized.

  As described above, the power conversion device according to the present invention can configure all the control power supplies for the other semiconductor switches from one control power supply. Therefore, the device can be downsized, which is useful as a power conversion device for electrical equipment. Is.

1001 1st semiconductor switch 1002 1st control circuit 1003 Control power supply 1010 DC low voltage side capacitor 1101 2nd semiconductor switch 1102 2nd control circuit 1103 Semiconductor switch capacitor 1110 DC high voltage side capacitor 1111 1st diode 1112 1st Resistor 1201 third semiconductor switch 1202 third control circuit 1203 bidirectional semiconductor switch capacitor 1211 second diode 1212 second resistor 1301 fourth semiconductor switch 1302 fourth control circuit 1401 bidirectional semiconductor switch

Claims (3)

A unidirectional semiconductor switch element,
A diode element connected in antiparallel to the unidirectional semiconductor switch element, and comprising a plurality of semiconductor switches,
One end of the first semiconductor switch and one end of the second semiconductor switch are connected in series, the other end of the first semiconductor switch is connected to a DC low voltage line, the other end of the second semiconductor switch Is connected to the DC high voltage line,
An output terminal of a two-level inverter that generates a pseudo AC potential is provided on a connection line between the first semiconductor switch and the second semiconductor switch,
One end of the third semiconductor switch and one end of the fourth semiconductor switch are connected in series so that the anode of the diode element is common, and the other end of the third semiconductor switch is connected to the output terminal. , The other end of the fourth semiconductor switch is connected to a direct current neutral point between the high voltage line and the low voltage line, and a bidirectional semiconductor switch and the low voltage line. Connected control power supply,
A semiconductor switch capacitor connected to the connection line between the second semiconductor switch and the output terminal,
A bidirectional semiconductor switch capacitor provided with the potential of the anode as a reference,
The positive electrode of the control power supply and the positive electrode of the control power supply capacitor for the semiconductor switch are connected via a first diode and a first resistor,
The power converter in which the positive electrode of the control power supply and the positive electrode of the bidirectional semiconductor switch capacitor are connected via a second diode and a second resistor. The third semiconductor switch and the fourth semiconductor switch are MOSFETs, and the diode element forming the third semiconductor switch and the fourth semiconductor switch is a parasitic diode of the MOSFET. The power conversion device according to claim 1. The power conversion device according to claim 1 or 2, wherein the third semiconductor switch is turned on while the second semiconductor switch is turned off.

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