General purpose variable frequency inverter using integrated power modules and LSI

The general purpose variable frequency inverter was developed. The main circuit is composed of only two integrated power modules, the one is three-phase bridge-connected rectifier module consisting of three thyristors and three diodes, and the other is three-phase bridge connected transistor inverter module consisting of six Darlington transistors, six free-wheeling diodes and one auxiliary diode. A custom-mode LSI is used in the control circuit associated with ROM which includes many voltage-frequency control patterns for general purpose motor drives. The transistor inverter has three voltage control modes, that is, PAM mode, PWM mode and combined mode, in order to improve the adaptability for fast response or quiet drives.