SU964928A1 - Controllable transistorized inverter - Google Patents

Description

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The invention relates to a converter technique and can be used in power supply and electric drive systems.

Adjustable transistor inverters are known, containing transistors and an output transformer, the primary winding of which has taps that are switched by the relay contacts in the control process. In order to prevent a deep decrease in the output voltage at the moment of opening the relay contacts, diodes connected in series into the inverter power circuit are inserted in this circuit, as a result of which the efficiency of inverter C1 decreases.

Also known is an adjustable inverter containing transistors, an output transformer, taps of at least one of the windings of which are connected to relay contact groups connected to chains of counter-connected threshold elements. The reliable operation of each of the contact groups of this inverter is largely determined by the switching voltage, which is equal to the reference level of the corresponding threshold element, slightly exceeding the amplitude of the switching voltage of the switched winding part 2.

 The purpose of the invention is to increase the reliability of the device.

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The goal is achieved by the fact that, in a regulated transistor inverter containing transistors, an output transformer, the taps of at least one of whose coils are connected to relay contact groups connected by hooks of oppositely included threshold elements, these chains

20 are connected between each movable contact of the aforementioned relay groups and the corresponding outlets from the middle points of the switched parts of said winding, the reference level

each threshold element is above half the amplitude of the voltage of the corresponding switched portion of the winding

Fig. 1 shows a two-phase adjustable inverter circuit with contact relay groups in the "primary winding of the output transformer; in fig. 2 - the same in the secondary winding.

Inverters contain transistors 1 and 2, the output transformer 3 taps one of the windings of which are connected to the contact groups a, c, d (a, c, d) relay, a chain of counter-connected Zener diodes 5-8 connected between the corresponding moving contacts a (a) relay groups and middle points b (b) of the corresponding switched parts of the winding of the transducer 3 The stabilization voltage of the zener diodes 5-8 exceeds the amplitude of the voltage of the switched part of the winding by a small amount.

Ineurtor (Fig. 1) works as follows.

Transistors 1 and 2 operate in a key mode in antiphase. In this case, alternating voltage of a rectangular shape is formed on the windings of the transformer 3. When a relay trips and releases, its contact groups switch over the primary windings, changing the transformer ratio 3. In this case, step-by-step voltage regulation on the load 9 occurs. The presence of stabilitron chains $ -8 eliminates deep dips in the output voltage at the moments of switching the contact groups. The working current of the primary circuit passes a large part of each device operation cycle through the contact groups of the relay i and only during their switching through zener diodes. This is achieved by the fact that the stabilization voltage of the latter is chosen slightly higher than half of the maximum possible voltage amplitude of the switched part of the primary otj winding of the transformer 3.

In addition, at the indicated connection of the zener diodes, the contact groups of the relay 4 with the permissible switching voltage are significantly lower than the supply voltage of the inverter, since the switching voltage is approximately equal to half the amplitude of the switching voltage of the primary winding of the transformer 3.

The operation of the inverter (Fig. 2) is similar to that considered. Such step-adjustable inverters can also be made by single-ended and bridge circuits.

Thus, the indicated connection of chains of counter-included threshold elements reduces the voltage switched by contact groups, which increases the reliability of the device.

Claims (2)

1. US Patent No. 2959726, cl. H 02 M 7/537, 1971. 2. USSR author's certificate number 535697, cl. H 02 M 7/537, 1975. a c