CONTROLLING METHOD OF REACTIVE POWER COMPENSATING TYPE CYCLO CONVERTER

摘要

PURPOSE:To eliminate the variations in the reactive power without any special reactive power compensating device by controlling a circulating current so that a lagged reactive power of a cyclo converter and an advanced reactive power of a phase advancing capacitor are cancelled between each other. CONSTITUTION:When AC current of a variable frequency is fed to a single phase load LOAD, the phase advancing capacitor C is connected to a power source of the cyclo converter CC. A constant advanced current Icap is provided to the capacitor C and an input current ICC to the converter CC. On the other hand, according to a deviation epsilon2 between a circulating current command value I0* based on a reactive power Q detected from a bus BUS by means of a reactive power arithmetic unit VAR and a circulating current I0 detected from the direction of a load current IL by a Schmitt circuit SH, the circulating current of the converter CC is controlled so that a lagged reactive power and an advance reactive power of the phase advance capacitor C are balanced to reduce the reactive power to zero. This can invariably control the basic wave power factor to be 1 viewed from the side of the power source eliminating variation in the reactive power without any compensating device such as thyristor bridge circuit.