SU385381A1 - TRANSISTOR INVERTER - Google Patents

Description

one

The invention relates to the field of scraper technology and automation, and can be used, for example, in power systems for synchronous hysteresis electric motors with adjustable frequency of the supply voltage according to a given law. To relinquish such electric motors, a frequency change relay is required.

In known circuits for this purpose, frequency switching blocks are usually used, the presence of which complicates the circuit.

In a lredlool inverter, the relaying nature of the regulating characteristic is provided by simply introducing additional wiring on the switching transformer connected in series with capacitors of the RC capacitor included in the inverter.

The principal electrical circuit of the device proposed (shown in the drawing.

Inve, rtor contains resistive-capacitive dividers made up of resistors 1-4 and capacitors. 5-8; switching transistors 9 and 10; switching transformer on cores //, 12 with common windings - primary 13, secondary 14 .k 15, as well as internal viral control windings 16, and 17, connected in series with each other; . Output transformer 18, limiting resistors 19, 20 and 21; feedback resistor 22; input terminals 23 and feedback loop 25; 2ti LAYA capacitor mode selection; terminals 27, 28

for connecting the supply voltage.

To create a relay mode of operation of the inverter in one of the shoulders of a capacitive divider, a winding feedback 25 is included, covering one of the switching cores

transformer.

The device works as follows. With an open circuit and control, the device operates as a conventional self-excited half-bridge inverter. By connecting the control windings to the current sensor, one of the cores (the core 11 at the specified polarity of the input signal and the open transistor 10) is additionally magnetised, and the other core (12) is partially demagnetized. In the next half-period of oscillation, the influence of the control current on the magnetization reversal of the cores changes by P; The cores are non-magnetic over the limiting hysteresis loop only for small

control current values. A further increase in this current leads to the fact that, due to the demagnetizing effect of resistor 22 and capacitor 26, the cores will begin to magnetize by means of a partial symmetric PR.Tl m hysteresis.

When the positive feedback winding 25 is turned on, the linearity of the adjustment characteristic is disturbed. As the control current increases, the current flowing through the capacitor 5 increases, and the amplitude of the winding 25 compensates for the amplitude of the control winding 16, as a result of which the frequency remains almost constant at a certain value of the control current. When the control current reaches a certain value / srab, the equilibrium ampered state is broken, and the frequency rises sharply.

A further increase in the control current does not introduce a significant change in the frequency. Reducing the control current to some value / off less than / srab leads to a dramatic decrease in frequency to the nominal value.

The output signal of the master oscillator is removed from the output winding of the transformer 18, included in the half-bridge circuit of co-capacitors 7, 8, resistors 3, 4, and transistors 9, 10, or in any other way.

The feedback windings can be located on both transformer cores (//, 12 and B both voltage divider arms are connected (in series with capacitors 5 and (5).

Subject invention

Transistor inverter with adjustable frequency output voltage, made according to half-bridge circuit with a resistive-capacitor voltage divider and a two-core switching transformer, magnetised by a control-current winding bypass capacitor, characterized by the fact that, in order to impart a frequency-current tuning component, to a volt-voltage control unit. kind of capacitor circuit

This voltage divider is connected in series with the windings located on separate cores of the switching transformer.

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