JPH09149662A - Drive circuit for semiconductor switch element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and cost of a driver circuit for semiconductor switch element by decreasing the number of components. SOLUTION: The driver circuit for semiconductor switch element comprises two DC power supplies 1a, 1b for driving six semiconductor switch elements 2 connected in three-phase bridge, six driving signal switches SU-SZ for controlling the switching of semiconductor switch elements 2, and three diodes DU-DW. Alternatively, the driver circuit for semiconductor switch element comprises a DC power supply for driving the six semiconductor switch elements 2 connected in three-phase bridge, six driving signal switches SU-SZ for controlling the switching of semiconductor switch elements 2, at least three capacitors CU-CW, and three diodes DU-DW.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a three-phase bridge-connected semiconductor switch element used in an inverter for generating a three-phase alternating current.

[0002]

2. Description of the Related Art Conventionally, a circuit as shown in FIG. 3 has been used as a drive circuit for driving a semiconductor switch element of a three-phase inverter used for variable speed driving of an AC motor.

In FIG. 3, reference numeral 2 denotes a semiconductor switching element in which six transistors U, V, W, X, Y, and Z are connected in a three-phase bridge connection. In the example shown in the figure, since a three-phase AC motor is connected as a load, a diode for processing the inductive component is connected in antiparallel with each transistor. 3 is a multi-tap transformer, which has 4 secondary windings for each primary winding, and 3 between each secondary winding.
Structural considerations have been made to ensure insulation against the voltage between each phase. The multi-tap transformer 3 may be composed of a power supply transformer for simply performing voltage conversion or may be composed of a switching transformer of a switching power supply circuit. In each case, the secondary side output is a diode DU, DV, Rectified by DW and DL, four independent DC power sources PU, PV, PW, and PL are configured. S
U, SV, SW, SX, SY, and SZ are drive signal on / off switches for controlling the on / off of the respective transistors U to Z of the semiconductor switch element 2 and may be constituted by semiconductor switches.

In the above-described structure, the transistor U connected to the positive electrode bus of the semiconductor switching element 2,
Since the emitter potentials of V and W are different from each other, the power supply for driving these transistors is required to have insulation characteristics sufficient to withstand the voltages between the three phases. On the other hand, the transistors X, Y, and Z connected to the negative bus of the semiconductor switch element 2 have the same emitter potential, so that each drive power supply is also configured by one common power supply. Therefore, the transistors U, V, W, and X to Z are driven by appropriately transmitting the electric power from four independent DC power sources each having insulation between each phase by the drive signal ON / OFF switch. Become.

[0005]

However, the above configuration requires four independent DC power sources, which are insulated from each other. Therefore, the size of the multi-tap transformer for realizing the insulation structure is increased, and a device accompanying it is required. In addition to the increase in size, there was the problem of increasing costs due to the increase in the number of parts.

In view of the above-mentioned problems, the present invention provides a drive circuit for a semiconductor switch element, which can reduce the size and cost of the device with a small number of parts.

[0007]

In order to solve the above problems, a drive circuit for a semiconductor switching device according to the present invention includes two DC power supplies for driving six semiconductor switching devices connected in a three-phase bridge. , 6 drive signal ON / OFF switches for controlling ON / OFF of the semiconductor switch element, and 3 diodes.

Further, at least one DC power source for driving the six semiconductor switching elements connected in the three-phase bridge connection, six drive signal ON / OFF switches for controlling ON / OFF of the semiconductor switching elements, and at least It is equipped with three capacitors and three diodes.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has
By using two DC power supplies, the three diodes can ensure insulation between the phases.

Further, among the six semiconductor switching elements, three semiconductor switching elements connected to the negative bus bar are fired before the start of operation, thereby using one DC power source and the three diodes. Therefore, insulation between the phases can be secured.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a drive circuit for a semiconductor switch element. Reference numerals 1a and 1b denote insulated DC power supplies. Reference numeral 2 denotes a semiconductor switch element. Here, six bipolar transistors U, V, W and X are provided. Y and Z are 3-phase bridge connected. Further, since the three-phase AC motor is connected as the load, the diode for processing the inductive component is connected in antiparallel to each transistor. DU, DV, DW are diodes, SU, SV, S
W, SX, SW, and SZ are drive signal on / off switches that control the transmission of drive power to the semiconductor switch elements U to Z.

The operation of the above arrangement will be described. Now turn on the transistor U of the semiconductor switching device 2
When the drive signal on / off switch SU is turned on to turn it on, electric power is transmitted from the DC power supply 1a to the DC power supply 1a via the drive signal on / off switch SU, the base of the transistor U, the emitter of the transistor U, and the diode DU. .
The transistors V and W are similarly driven. Further, when the drive signal on / off switch SX is turned on to turn on the transistor X of the semiconductor switch element 2, the DC power source 1
DC power supply 1 via drive signal ON / OFF switch SX, base of transistor X, and emitter of transistor X from b
Power is transmitted to b. The transistors Y and Z are similarly driven. Here, the emitter potentials of the transistors U, V, and W are different, but the potential difference between them is the diode DU, D.
It is blocked by V and DW to ensure insulation.

As described above, according to the present embodiment, two DC power supplies for driving the six semiconductor switch elements connected in the three-phase bridge connection, and six DC power sources for controlling ON / OFF of the semiconductor switch elements. By providing the drive signal on / off switch and the three diodes, the semiconductor switch element can be driven with a small number of power supplies. Claim 1 of the present invention is particularly suitable for driving a semiconductor switch element such as a bipolar transistor which requires a relatively large drive power, as shown in the present embodiment.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a drive circuit for a semiconductor switch element. Reference numeral 1 is a DC power source, 2 is a semiconductor switch element, and here, six MOS gate transistors U, V, W, X, Y and Z are three-phase bridge connected. ing. Further, since the three-phase AC motor is connected as the load, the diode for processing the inductive component is connected in antiparallel to each transistor. DU, D
V, DW are diodes, SU, SV, SW, SX, S
W and SZ are drive signal on / off switches for controlling transmission of drive power to the semiconductor switch elements U to Z, CU, CV, and CW.
Is a capacitor.

The operation of the above arrangement will be described. First, before starting the operation of the inverter, the drive signal on / off switches SX, SY, SZ are turned on to turn on the transistor X,
Turn on Y and Z. At this time, for example, a current flows through the capacitor CU through the path of the DC power supply 1, DU, CU, the transistor X, and the DC power supply 1, and the electric charge is accumulated. Similarly, the capacitors CV and CW are also charged. By the above operation, the three capacitors C as DC power supplies separated from each other
U, CV, CW are formed, and transistors U, C
The drive power source for V and W.

Next, when the drive signal on / off switch SU is turned on to turn on the transistor U, the capacitor CU is turned on.
Via the drive signal ON / OFF switch SU, the gate of the transistor U, and the emitter of the transistor U to the capacitor C
Power is transmitted to U. The transistors V and W are similarly driven. When the drive signal on / off switch SX is turned on to turn on the transistor X, the DC power supply 1
Electric power is transmitted to the DC power supply 1 via the drive signal ON / OFF switch SX, the gate of the transistor X, and the emitter of the transistor X. The transistors Y and Z are similarly driven.

Further, during the operation of the inverter, the transistors X, Y and Z are sequentially turned on, so that the capacitors CU, CV and CW are continuously charged in the same route as before the start of the operation.

Here, the emitter potentials of the transistors U, V, W are different, but the potential difference between them is the diode DU, D.
It is blocked by V and DW to ensure insulation.

As described above, according to the present embodiment, one DC power source for driving the six semiconductor switch elements connected in the three-phase bridge connection and the six DC power sources for controlling the ON / OFF of the semiconductor switch elements. Drive signal ON / OFF switch and at least 3
By providing one capacitor and three diodes, it is possible to drive the semiconductor switch element with one power source. Claim 2 of the present invention is, as shown in this embodiment, MO
It is particularly suitable for driving a semiconductor switch element such as an S gate transistor that can be driven with a relatively small drive power.

[0021]

As described above, according to the present invention, there are provided two driving circuits for driving six semiconductor switching elements which are three-phase bridge-connected.
It is possible to drive the semiconductor switch element with a small number of power sources by providing a single DC power source, six drive signal on / off switches for controlling the on / off of the semiconductor switch element, and three diodes. Miniaturization and cost reduction are possible.

Further, at least one DC power source for driving the six semiconductor switch elements connected by the three-phase bridge connection, six drive signal ON / OFF switches for controlling ON / OFF of the semiconductor switch elements, and at least By providing the three capacitors and the three diodes, the semiconductor switch element can be driven by one power source, and the device can be downsized and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a drive circuit diagram of a semiconductor switch element according to an embodiment of claim 1 of the present invention.

FIG. 2 is a drive circuit diagram of a semiconductor switch element according to an embodiment of claim 2 of the present invention.

FIG. 3 is a drive circuit diagram of a conventional semiconductor switch element.

[Explanation of symbols]

 1 DC power supply 2 Semiconductor switch element 3 Multi-tap transformer SU to SZ Drive signal on / off switch DU to DW diode CU to CW capacitor 1a DC power supply 1b DC power supply

Claims (2)

[Claims] 1. A direct current power source for driving six semiconductor switch elements connected in a three-phase bridge connection, six drive signal on / off switches for controlling on / off of the semiconductor switch elements, and three. A drive circuit for a semiconductor switch element, which comprises a plurality of diodes and ensures insulation between each phase by the diodes. 2. A direct current power source for driving six semiconductor switching elements connected by a three-phase bridge, and six drive signal on / off switches for controlling on / off of the semiconductor switching elements. Before starting the operation, three capacitors and three diodes are provided, insulation between the phases is secured by the diodes, and three semiconductor switching elements connected to the negative bus of the six semiconductor switching elements are started. A drive circuit for a semiconductor switch element, which is characterized by being turned on.