Abstract: In an apparatus for controlling a power converter, which is adapted to control, in accordance with a PWM system, a voltage-type inverter for system interconnection interposed between a d.c. power source and an a.c. system to interchange power therebetween, a scheme is employed to switch voltage amplitude adjustment signals of respective phases depending upon an output voltage phase signal provide a phase voltage amplitude. Energization periods of respective controllable rectifier elements of the power converter are determined on the basis of the phase voltage amplitude and the output voltage phase signal. Employment of such a scheme makes it possible to independently control the output voltage of the inverter every phase or with respect to both positive and negative sides of the phases, respectively.

Abstract: In an apparatus for controlling an inverter which delivers a current vector with a specific number of phase positions to an AC load, there are provided a phase difference detecting circuit and a commutation control circuit. The phase difference detecting circuit detects a phase difference (.theta.) between the output current vector delivered from the inverter and a phase angle instructed, while the commutation control circuit controls the commutation of the inverter by comparing the phase difference (.theta.) thus detected, or an integration of the phase difference (.theta.) with respect to time, with a positive reference value and a negative reference value.

Abstract: In a method and apparatus for controlling an output current of a controlled rectifier connected to an AC power supply, by firing angle control of the controlled rectifier in accordance with the result of comparison of a value corresponding to the rectifier output current with a predetermined reference value, an average value of a detected rectifier output current over a period having a length equal to an integer multiple of the average period of the firing angle control is calculated, and a signal for firing the controlled rectifier is produced at an angle determined in accordance with comparison of the calculated average value with the reference value.