Induction Machine Frequency Control: Three-Phase Bridge Inverter Behavior and Performance

Some working modalities of a three-phase bridge inverter, where the first-harmonic amplitude of the generated voltage varies by means of the output voltage choppering are presented. The variable-frequency inverter is used most often in induction machine speed control. The types of inverter proposed are compared with the most common type having a variable supply voltage, as to the circuitry complexity and the alternating torque generated in the induction machine. The driving circuits of the two choppered inverter are described in the Appendix.