SU188564A1 - machine frequency converter compounder - Google Patents

Description

At present, induction asynchronous and synchronous-reactive machine frequency converters are widely used. In such converters, a sharp drop in voltage is observed when they are connected to consumers whose loads are advantageously inductive.

However, the principle of operation of these transducers eliminates the possibility of controlling the excitation. As a result, there is a significant underutilization of power converters. For example, with consumers in which cos 1f 0.6-0.7, the loading power of the I-75 and C-572 serial converters does not exceed 50% of their nominal power. In addition, the starting properties of motors operating with such converters are deteriorated.

To automatically stabilize the voltage of machine frequency converters, it is proposed to use a compounding device using the principle of longitudinal capacitive compensation.

In this case, the capacitors are connected in series to the line between the source and the current collector of increased frequency. To reduce the required capacitance, capacitors are connected to the line using series transformers.

The drawing shows a circuit for connecting the device to the load supply circuit of a three-phase frequency converter.

In the line between the frequency converter / and its load 2, the primary windings of the serial transformer 3 are connected. To the secondary windings of the transformer, capacitors 4 are connected.

The reactive capacitive power of series-connected capacitors is, as you know, in quadratic dependence on the current. For the proposed scheme, this dependence will be:

Q.

l: 2 w C

where QC is capacitive power; / - load current; C - capacitor capacitance;

with - the current frequency;

K. - the transformation ratio of serial transformers. The increase in load current causes, as can be seen from the above formula, a corresponding increase in capacitive power, providing compensation for the inductive power of the load. The growth of the latter under normal operating conditions of the converter leads to a weakening of its magnetic field and a decrease in voltage.

The proposed device can also be used to stabilize the voltage of static frequency converters.

Subject invention

A device for compounding a frequency converter into an output

the circuit of which includes capacitors and a current transformer, characterized in that, in order to increase the efficiency by stabilizing the voltage at the output of the converter, the capacitors are connected in a delta circuit and connected to the secondary winding of the specified transformer.

.-ulgl.

L,

k - II