Determination of Commutation Sequence with a View to Eliminating Harmonics in Microprocessor-Controlled PWM Voltage Inverter

The commutation pattern of PWM inverters operated under elimination of harmonics and control of the fundamental wave amplitude is highly complex. The sequences determined by the proposed method permit control of the harmonic amplitudes of a single-phase and a three-phase inverter. A microcomputer (8085 CPU)-controlled three-phase unit embodying this principle is described. It is designed for a three-phase output voltage in the 1-45 Hz interval with the 5th, 7th, and 11th harmonics eliminated, and with the fundamental wave amplitude proportional to the output frequency.