SU1077036A1 - Bridge inverter - Google Patents

Abstract

1. A BRIDGE INVERTER containing power transistors, a control unit, the outputs of which are connected to the input circuits of said transistors, current sensors, the outputs of which are connected to the blocking inputs of the control unit, characterized in that, in order to increase reliability by eliminating through currents, input circuit: power transistors are connected in series with the inputs of the corresponding current sensors. a SL about O 00 O5

Description

2. Inverter pop „1, different from and with the fact that in quality

and - current sensors are used current transformers.

This invention relates to electrical engineering and can be used in power converters. A bridge inverter is known which contains power transistors, a control unit whose outputs are connected to the input circuits of said transistors. To eliminate the through currents, the input circuits of the power transistors include saturated cores with chokes that ensure the switching on of the next power transistor 1. The disadvantage of this inverter is the lack of automatic time delay control. The closest to the proposed is a bridge inverter containing power transistors, the control unit The outputs of which are connected to the input circuits of these transistors, current sensors whose outputs are connected to the blocking inputs of the control unit. and 2. However, in the specified inverter, the through currents are not completely eliminated since the automatic delay of switching on the next pair of transistors is valid only until one of the pair of previously connected transistors is locked, the absorption time of the excess carriers is shorter. This reduces the reliability of the inverter. The purpose of the invention is to increase the reliability of the inverter by completely eliminating the through currents. This circuit is achieved by the fact that in a bridge inverter containing power transistors, the control unit whose outputs are connected to the input circuits of these transistors, current sensors whose VYHOF1 are connected to the blocking inputs of the control unit, the inputs of the corresponding current sensors are sequentially included in the power transistors . Transformer current can be used as current sensors; mators Figure 1 shows an electrical circuit of a bridge inverter; on Fig.2 time diagrams. The inverter contains power transistors 1-4, control unit 5, consisting of nodes 6 and 7 of the pulse shapers and node 8 of the control. Transformers 9 and 10 are used as current sensors, each trans current format has two primary (current sensor inputs / and one secondary winding (current sensor output | current transformer 9 primary windings 11 and 12 for measuring the base currents of transistors 1 and 4, respectively, and the secondary winding 13 for transmitting information about the base currents to the adjacent blocking input of the driver 6 of the pulses of the control unit 5. The primary windings 14 and 15 of the transformer 10 are designed to measure the currents of the bases of transistors 2 and 3, respectively, and toric winding 16 - to transmit information about the base currents to another blocking input of the pulse generator 7 of the control unit 5. The load 17 is connected to the output pins. The pulse shaping nodes 7 and 7 have a matching circuit and pre-final stages acting on the input. Node 8 The control unit contains a generator. FIG. and 3, the base currents of the transistors 2 and 3, the current through the winding 16, the power current of the transistors 1-4. The device works as follows. Suppose that the bases of transistors of synchronous pair 1 and 4 are supplied with positive control pulses 18 at time t. Transistors 1 and 4 are open and current 24 flows through them. Transistors 2 and 3 of the second synchronous pair are closed. When the polarity of the control pulses 18 from the generator of 7 pulses at time t2 changes, the reverse currents 19 of the bases of transistors 1 and 4 respectively flow through the primary sheaves 11 and 12 of the current transformer 9, which ensures the flow of the current pulse 20 into the mountain winding 13,: duration which is determined by the maximum resorption time of the minority carriers tp of the base of one of the transistors 1 and 4 (for example 1). This current impulse enters the shaper 6 pulse generator, blocking, surrogate sigal, and this ensures

the delay in opening the rear transistors 2 and 3. The blocking signal is removed when the reverse currents of the 20 bases decrease to almost zero at the moment when the switching off of the transistor 1 stops. The load current 24 through 5 transistors 1 and 4 is interrupted at the time of the end of desoldering in transistor 4.

Transistors 2 and 3 open upon receipt of positive control-tO pulses 21 at the time of locking the transistor 1, Ilpk changing the polarity of the control pulses 21 from the driver forcing b pulses through the primary windings 14 and 15 of the transformer 10 -15 ka, reverse currents 22 begin to flow transistors 2 and 3, respectively, which ensures the flow of current pulse 23 in the secondary winding 16, the duration of which is determined by the maximum resorption time of minority base carriers of one of the transistors 2 and 3 (for example 3). This pulse the current flows into

the pulse shaper 7 blocks the control signal, which ensures the opening delay of transistors 1 and 4. The blocking signal is removed when the pulses of currents 22 of the bases of transistors 2 and 3 terminate. The load current 24 through transistors 2 and 3 is interrupted at the time of the end of resorption in the transistor 2. As a result, the load current 24 has discontinuities in time equal to the differences in the absorption times of transistors 2.3 and 1.4, respectively.

Thus, the introduction of current sensors to measure base currents made it possible to use information on the resorption process of minority carriers in the bases of transistors to block the turn-on signals of previously turned off power transistors until the moment when the previously turned on pair of power transistors completely shut down, which ensures the complete elimination of through currents in the inverter and lays out its reliability.

Claims (2)

1. A BRIDGE INVERTER containing power transistors, a control unit whose outputs are connected to the input circuits of these transistors, current sensors, the outputs of which are connected to the blocking inputs of the control unit, characterized in that, in order to increase reliability by eliminating through-currents, the input circuits :: power transistors are connected in series with the inputs of the respective current sensors. 2. Inverter pop. 1, distinguished by the fact that current transformers are used as current sensors.