SU1198686A1 - Transistorized a.c.switch - Google Patents

Description

The invention relates to electrical engineering and can be used in voltage converters of secondary power systems.

The purpose of the invention is to increase efficiency by reducing the voltage drop across the inverted-on transistor.

The drawing shows the electrical circuit of the proposed key bilateral conduction, performed on pnp-type transistors.

The key contains two of the same type of transistor I and 2, the collectors of which are included in the AC power circuit. Interconnected emitters of transistors 1 and 2 are connected to the beginning of the secondary winding of the input matching transformer 3, the end of which is connected to the bases of transistors through limiting resistors 4 and 5. The protective diodes 6 and 7 are connected by cathodes to the collectors ’of transistors 1 and 2, and by anodes to the tap of the secondary winding of the input matching transformer 3.

The key works as follows.

In the absence of control voltage, the bases of both transistors are closed to the emitter through the low resistance of the transformer secondary winding and the transistors are closed at the same time. Almost all the voltage of the switched circuit, depending on its polarity, is applied to one of the transistors 1 or 2. At the same time, it is closed and connected to the collector

2

This transistor diode. The collector junction of the second transistor and __ the second diode are shifted in the forward direction and the voltage drop across

5 of them from the reverse current collector of the first transistor and the reverse current of the first diode is negligible.

When changing the polarity of the switched voltage situation changes

10 on the reverse due to the symmetry of the key.

Upon receipt of the opening control signal in the base circuit of both. transistors is set redundant

15 current sufficient for their saturation at the maximum switched current.

Depending on the polarity of the voltage in the switched circuit, one of the transistors turns on

20 in the forward direction of the collector current, and the second in the inverse.

However, the inverse voltage on the collector of the transistor in the proposed key scheme is limited by a diode on

25 is much lower, given by calculation, the level, which is determined by the difference between the direct voltage drop across the open diode and the control voltage, at the tap of the secondary winding of the transformer. As a result, the inverse mode of operation of transistors is greatly facilitated, and the total residual voltage on the key for large values of the switched current can be significantly reduced.

Claims (1)

TRANSISTOR KEY OF CHANGES, ΟΓΟ CURRENT, containing two transistors of the same type, the collectors of which are included in the AC power circuit, input matching transformer, the secondary winding of which is connected to the combined emitters of the transistors, and the end through the limiting resistors to their bases, and> two diodes, connected to the collectors of transistors by the first leads of the cathodes, if η-ρ-η-type conductivity type transistors are used, or anodes, if pnp-type transistors are used, which is similar to i, in order to reduce voltage drops and total power losses at the key, as well as facilitating the inverse mode of operation of transistors, the second terminals of the diodes are connected to the tap of the secondary winding of the specified transformer. , ® 1 i!