JPH061975B2 - Switching transistor parallel connection circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a switching transistor parallel connection circuit capable of increasing the operating current by increasing the number of switching transistors connected in parallel.

[Conventional technology]

In devices that perform power conversion by turning on / off the circuit current, such as inverter devices and chopper devices, switching operations can be performed at extremely high frequencies, so transistors are often used as switching elements for turning the circuit current on / off. Has been done. Therefore, in order to be suitable for turning on / off such a circuit current, for example, a transistor as a switching element in which a diode for feedback is connected in anti-parallel is used. Therefore, the antiparallel circuit of the transistor and the diode will be referred to as a switching transistor unit below.

FIG. 2 is a main circuit connection diagram showing a conventional example of parallel connection of switching transistor units. The current capacity of the transistor has been increasing in recent years, but in order to further increase the current capacity of the power conversion device, by connecting switching transistor units in parallel,
The above requirements will be met.

FIG. 2 shows a case of a power conversion device in which three sets of switching transistor units 10, 20, and 30 are connected in parallel and used, and the DC power from the DC power supply 2 is supplied by these three sets of switching transistor units. The case of converting and supplying power to the load 3 is shown. At this time, the three sets of switching transistor units 10, 20, 30 are simultaneously turned on / off corresponding to the base signal from the base drive circuit 4 common to them. Take action. If the power conversion device is an inverter or a chopper, the circuit configuration will correspond to each, but since this has nothing to do with the present invention,
Illustration of this portion is omitted.

As shown in FIG. 2, when a plurality of switching transistor units are connected in parallel and they are turned on / off at the same time, the most important thing to note is the current imbalance between the switching transistor units. Therefore, in FIG. 2, by equalizing the wiring inductances 11 and 2131 on the emitter side of each switching transistor unit, the direct current amplification factor h _FE of each transistor is made uniform to balance the current. .

FIG. 3 is a main circuit connection diagram showing a conventional example of parallel connection of more switching transistor units than in FIG.
0, 20, 30, 40, 50 are connected in parallel, and the signals from the common base drive circuit 4 are turned on / off at the same time to convert the DC power from the DC power supply 2 into the load 3. To supply. Reference numerals 13, 23, 43 and 53 are wiring inductances. Also the symbols 12, 22, 32, 42 and 52
Is the junction capacitance of the transistors that make up each switching transistor unit.

[Problems to be solved by the invention]

By the way, as in the conventional circuit of FIG. 3, when the number of switching transistor units connected in parallel increases, the wiring distance becomes longer. Due to the potential difference between the switching unit and the unit 10 (collector side of the unit 10) or between the point A and the point C (that is, the collector side of the transistor unit 50), a current imbalance occurs in each switching transistor unit. Also, as shown, each transistor has a small value,
Since there is a junction capacitance, there is an inconvenience that, for example, a resonance phenomenon occurs due to the junction capacitance 12 and the wiring inductances 13 and 23. This resonance phenomenon may occur due to the junction capacitance 22 and the wiring inductance 23, the junction capacitance 42 and the wiring inductance 43, or the junction capacitance 52 and the wiring capacitances 43 and 53, for example.

Therefore, because of the inconvenience such as the current imbalance or the occurrence of the resonance phenomenon, the number of switching transistor units in parallel cannot be increased, and thus the current capacity of the power conversion device is limited.

Therefore, an object of the present invention is to improve the current imbalance and suppress the resonance phenomenon, thereby enabling a large number of switching transistor units to be connected in parallel and increasing the current capacity of the power conversion device.

[Means for solving problems]

In order to achieve the above-mentioned object, the parallel connection circuit of the present invention has a saturable reactor having a high impedance characteristic with respect to a transient change connected in series to the collector side of a switching transistor, and a plurality of sets of the series circuit are connected. They shall be connected in parallel with each other.

[Action]

The present invention focuses on the fact that a resonance phenomenon occurs in a high frequency region, and a resonance circuit composed of a junction capacitance and a wiring inductance existing in a switching transistor has a high impedance against a transient change. By inserting a saturable reactor with characteristics, the resonance phenomenon of the circuit is suppressed, and at the same time, this high impedance prevents current imbalance during switching operation, which is an inconvenience when multiple switching transistor units are connected in parallel. To prevent the occurrence of.

〔Example〕

FIG. 1 is a main circuit connection diagram showing an embodiment of the present invention,
In FIG. 3, as in the case of the conventional circuit described above, five sets of switching transistor units are connected in parallel.

In FIG. 1, five sets of switching transistor units 10, 20, 30, 40, 50, which are configured by an antiparallel connection of a transistor and a feedback diode, are operated by a signal from a base drive circuit 4 common to them. By turning on / off at the same time, the DC power from the DC power supply 2 is converted and fed to the load 3. These transistors have junction capacitances 12, 22, 32, 42, 52, respectively, and these When five switching transistor units are connected in parallel, wiring inductances 13,23,43,53 exist due to uneven wiring length, which is the same as in the conventional circuit shown in FIG. is there.

In the present invention, the saturable reactors 15, 2 are connected in series on the collector side of each switching transistor unit.
5,35,45,55 are connected separately. By connecting the saturable reactors in series in this manner, the resonance phenomenon due to the junction capacitances 12, 22, 32, 42, 52 of the transistors and the wiring inductances 13, 23, 43, 53 is suppressed. Furthermore, the saturable reactor presents a high impedance against transient changes, and the imbalance of the wiring inductance values connecting each switching transistor unit becomes almost zero, so that the switching transistor unit switches. It also prevents current imbalance during operation.

〔The invention's effect〕

According to the present invention, a large number of switching transistors are connected in parallel, and when performing power conversion by turning them on and off at the same time, separate saturable reactors are connected in series to each collector side of the switching transistor. Since this saturable reactor exhibits a high impedance with respect to transient changes, resonance phenomenon due to transistor junction capacitance and wiring inductance, as well as current imbalance caused by uneven wiring inductance values are generated. Since both can be suppressed, the number of parallel operation of the switching transistor units can be increased and the current capacity can be easily increased.

[Brief description of drawings]

FIG. 1 is a main circuit connection diagram showing an embodiment of the present invention, FIG. 2 is a main circuit connection diagram showing a conventional example of parallel connection of switching transistor units, and FIG. 3 is more switching transistors than FIG. It is a main circuit connection diagram showing the conventional example of parallel connection of units. 2 ... DC power supply, 3 ... Load, 4 ... Base drive circuit, 10, 20,
30,40,50… Switching transistor unit, 11,13,
21,23,31,43,53 ... Wiring inductance, 12,22,32,42,52
… Junction capacitance, 15,25,35,45,55… Saturable reactor.

Claims (1)

[Claims] 1. A parallel connection circuit of switching transistors having a junction capacitance, which has at least a high impedance characteristic against a transient change due to resonance between a wiring inductance existing in a wiring connecting the switching transistors in parallel and the junction capacitance. A parallel connection circuit for switching transistors, characterized in that separate saturable reactors each having the above are respectively connected in series to the collector side of the switching transistor, and a plurality of sets of the series connection circuits are connected in parallel with each other.