CONTROL METHOD FOR THREE-PHASE VOLTAGE CONTROL FOR SUPPLYING ASYNCHRONOUS MOTOR WITH ADVANCED ENERGY INDICATORS

摘要

A control method for transistor voltage control for a power supplying asynchronous motor with advanced energy indicators consists in connection of load phases to the power network through power keys within first part of supply voltage half-period, without changing characteristics thereof, within the other part of supply voltage half-period –via width modulation of supply voltage. Shaping the control pulses by a power transistor is made in a manner that the transistor opening start is synchronized with zero crossing supply voltage sine wave. Shaping voltage on the load within certain part of the supply voltage half-period is made via direct connection to the power supply network, within the next part of output voltage half-period – via voltage modulation with variable pulse duty factor, when the initial value of pulse duty factor is not constant value, but it is calculated by the control system depending on angle of opening voltage control transistors and changes in a sinusoidal manner from the initial value to zero.