JPS62285676A - Power converter - Google Patents

Abstract

PURPOSE:To realize quick turn-OFF by connecting four pairs of cascade- connection switching circuits in a single-phase bridge manner and turning these circuits ON-OFF in succession. CONSTITUTION:Cascade-connection semiconductor switching circuits 30, 40, 50, 60 constituted by connecting bipolar transistors and MOS FETs in series are bridge-connected, thus organizing a power converter. When two pairs of the cascade-connection semiconductor switching circuits 30 and 40, 50 and 60 connected in series to a power supply 10 are turned ON-OFF alternately, one is turned ON during a period when the other is turned OFF, thus forcibly flowing currents, then realizing quick turn-OFF.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Technical field to which the invention pertains] This invention relates to a bipolar transistor and a gold oxide m $
+W J+乍t νζ 2 books ri 4-ノ,
・) Cascode connection device ♂swie, which is composed of three consecutive cascode connections,
The present invention relates to a power conversion device using a circuit.

[Prior art and its problems]

For example, a power conversion device that converts direct current to alternating current, a so-called inverter, performs power conversion by sequentially turning on and off switching elements connected in a bridge, but inverters that perform pulse width modulation control, etc. In particular, a switching element capable of switching at high frequencies is desired.

FIG. 3 is a circuit diagram showing an example of a cascode-connected semiconductor switch circuit, which includes a high-current custom-made good bipolar transistor 3 and a metal oxide semiconductor field effect transistor (hereinafter MOS FET) with good high-speed switching characteristics.
(abbreviated as ) 4 are connected in series, and a diode 5 is connected in series.
A cascode-connected semiconductor switch circuit 2 is formed by connecting a flywheel diode 6 (or a constant voltage diode may be used) and a flywheel diode 6 as shown in the figure.

The on/off operation of the cascode-connected semiconductor switch circuit 2 is performed as follows. That is, a firing signal is applied to the bipolar transistor 3 via the pace drive circuit 7, and at the same time, the ignition signal is applied to the MOS FE via the gate drive circuit 8.
When both are turned on by giving an ignition signal to 'l' 4, the cascode-connected semiconductor switch circuit 2
From the positive pole to the negative pole! The flow flows. In order to cut off this current, bipolar transistor 3 and MOS
When the ignition signal applied to FET 4 is removed, MOS FE'r4 with high-speed switching operation is turned off first, so the current that was flowing until now is transferred to this MOS.
The bipolar transistor 3 can also be turned off safely and at high speed because it is turned off in a path that bypasses the FET, that is, a path from the collector of the bipolar transistor 3 to the pace diode 5 of the bipolar transistor 3 to the source side of the MO8FET 4.

However, if the current flowing through this circuit becomes zero before turning off the cascode-connected semiconductor switch circuit 2 in the on state, after the MO8FET4 is turned off by removing the ignition signal, the bipolar transistor 3 Because the current that should flow from its collector to the pace is zero, the carriers injected from the pace do not disappear quickly, so the bipolar transistor 3
The turn-off time becomes longer. Therefore, if the cascode-connected semiconductor switch circuit of the other arm connected in series is fired before the bipolar transistor 3 is turned off, a so-called boom short circuit may occur, causing excessive current to flow, damaging the element. Such inconveniences may occur. Therefore, in order to prevent such arm short-circuit accidents, a signal delay element is installed so that the firing signal is not applied to the other arm until a certain period of time has passed after the firing signal of one arm is removed. If this is provided, the switching operation at high frequencies will be inhibited, resulting in the disadvantage that the characteristics of the cascode-connected semiconductor switch circuit 2 composed of the bipolar transistor 3 and the MQSFET 4 will be lost.

[Purpose of the invention]

This invention uses bipolar transistors and MO8F E
To provide a power conversion system that can perform switching operations at high frequencies without causing arm short circuits by using a cascode IF semiconductor switch 1ai path configured in (support) column concatenation with "i". The purpose is to

[Key points of the invention]

This invention is based on bipolar transistors and
Two sets of cascode-connected semiconductor switch circuits configured in series with "ED" are connected in series to a power supply, and when one cascode-connected semi-conductor switch circuit is on, the other one is turned off alternately. In order to perform the gravity conversion by repeating , without providing a signal delay element f?, an OFF signal is given to one cascode follow-on semiconductor circuit and the other is turned on during the turn-off period. By applying a signal, the carriers of the bipolar transistor during turn-off are quickly annihilated to realize switching operation at a high 8 wave number, and the arm short circuit*a that occurs due to such high-speed switching operation can be The current is suppressed by means of current suppressing means, such as a reactor, inserted in series with these cascode-connected semiconductor switch circuits.

[Embodiments of the invention]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In Fig. 1, four sets of cascode Sakaki switch circuits (30, 40, 50, t5L) are connected in a single-phase bridge, and each cascode connected switch circuit is operated to turn on and off, thereby generating direct current. The DC power from the power source 10 is converted into AC power and supplied to the load "21). Here, each cascode connection switch circuit has the same configuration as the circuit diagram shown in FIG. A glue handle 31, 41, 51, 61 is connected in series to each cascode connected switch circuit.

The on/off signal to the cascode connection switch circuit blade connected to the positive electrode 1a11 of the DC power supply 10 is sent to the bipolar transistor from the base drive circuit 5z via the signal isolation circuit, and from the gate drive circuit 53 to the MOS FET. Given. Furthermore, the same on/off signal as above is transmitted between the cascode-connected switch circuits connected to the negative pole side of the DC power source 1° via the inverting collector 65 and the signal insulating circuit to the pace drive circuit 62 and the gate drive circuit. It is given from 63. Other cascode connection switch circuits I and 4
0 and 5, although not shown, a switch circuit 50.6
The on/off signal (ζ) is provided by a circuit having the same configuration as that for 0.

With the circuit configuration shown in FIG. 1, for example, when the ignition signal to the positive side cascode connection switch circuit (3) in the on state is removed and the turn-off operation begins, the negative side cascode connection switch circuit 6] Since ignition M is given to , the current flowing through the positive side cascode connection switch circuit blade immediately before this is zero, so the carriers press-fitted from the base of the bipolar transistor disappear quickly. Even if the turn-off time becomes longer due to the negative electrode 1u11 being turned off, current is actively caused to flow by firing between the cascode-connected switch circuits of the negative electrode 1u11, thereby realizing quick turn-off of the bipolar transistor.

However, since the arm short-circuit current that flows at this time is inserted in series with each cascode-connected switch circuit and is suppressed by the handles 51 and 61, there is no risk of element destruction due to excessive current flow.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention. In FIG. 2, four sets of cascode-connected switch circuits 30, 40, 50, and 60 form a single-phase inverter to convert the direct current output from the direct current power source 10 into alternating current power and supply it to the load. A signal Mh class circuit 54 is connected to the cascode connection switch circuit blade on the positive side of the DC power supply 10.
On/off signals are supplied from the pace drive circuit 52 and the gate drive circuit 53 via the pace drive circuit 52 and the gate drive circuit 53, and the pace drive circuit 62 is supplied to the negative side cascode connection switch circuit 60 via an inverting element 65 and a signal isolation circuit. As in the embodiment shown in FIG. 1, on-off signals are applied from the gate drive circuit 63 and the gate drive circuit 63.

In the second embodiment circuit shown in FIG.
The cascode connection switch circuit I of 11 is inserted in series with the cascode connection switch circuit I, and the acdle is not inserted in series with the cascode connection switch circuit 40 of negative I+111 and tjl,1. Even with this circuit configuration, the current when the arm is short-circuited can be suppressed to an appropriate value.
! :(Of course.

〔Effect of the invention〕

According to this invention, a bipolar transistor and a MOS
A power converter is formed by bridge-connecting cascode-connected semiconductor switch circuits configured by connecting FETs in series, and two
When operating a silk cascode-connected semiconductor main switch circuit alternately on and off, by turning on one side while the other is in the turn-off period, direct current is forced to flow and quick turn-off is achieved. At the same time, the large *a caused by arm short circuit can be suppressed by current suppressing means inserted in series with these cascode-connected semiconductor switch circuits, so that the switching operation at high frequencies, which is a characteristic of cascode-connected semiconductor switch circuits, can be sufficiently suppressed. It is possible to realize a high-performance power conversion device using this technology.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a second embodiment of the invention, and FIG. 3 is a circuit diagram showing an example of a cascode-connected semiconductor switch circuit. . 2.30,40,50.60...Cascode connection switch circuit, 3...Bipolar transistor, 4...
MOS FET.

Claims (1)

[Claims] 1) A bipolar transistor and a metal oxide semiconductor field effect transistor are connected in cascode, and a firing signal is applied to the base of these bipolar transistors and a gate of the metal oxide semiconductor field effect transistor to turn them on, and a turn-off signal is applied to both of them. two sets of cascode-connected semiconductor switch circuits and a current suppression means configured to perform firing by removing the ignition signal of the cascode-connected semiconductor switch circuit are connected in series with respect to a power supply, and one of the cascode-connected semiconductor switch circuits is configured to perform a turn-off period. 1. A power conversion device comprising means for alternately repeating an operation of turning on the other cascode-connected semiconductor switch circuit.