Control unit for non-circulating current type cycloconverter

摘要

The invention relates to a control unit to control a continuous cycloconverter of the non-circulating current type which performs frequency conversion of an AC power source using a semiconductor element a to perform commutation by the AC power source and variable speed operation of an AC motor. Sine/cosine waves as secondary magnetic flux directional signals are obtained by a sine/cosine wave generator based on the slip phase and the rotor phase of the motor; deviation between torque current set value supplied from a speed controller and torque current feedback value is outputted as torque voltage adjusted value by a torque current control element, and deviation between exciting current set value supplied from a magnetic flux controller and exciting current feedback value is outputted as exciting voltage adjusted value by an exciting current control element; the torque and exciting voltage adjusted values are converted into alternating voltage set values using the sine/cosine waves as parameters, and the torque current set value and the exciting current set value are converted into alternating current set values also using the sine/cosine waves as parameters; the alternating voltage set value and the alternating current set value converted are outputted to a control circuit to alternately operate switching of the semiconductor elements of positive and negative groups which constitute the cycloconverter, and the amplitude error and the phase error produced between the alternating current set value supplied to the cycloconverter and the alternating drive current actually supplied to the motor can be reduced significantly.