Technique for pulse elimination in pulsewidth-modulation inverters with no waveform discontinuity

To realise the full output potential of a PWM inverter, it is necessary to make the transition from a PWM output waveform to a square-wave output. This is usually achieved by dropping pulses from the PWM waveform, which results in step changes in the output voltage. It is shown that, generally, pulse dropping is unavoidable except with one particular type of inverter circuit. A waveform generation strategy is proposed for this type of inverter which allows the transition from PWM to square-wave output to be made without voltage-waveform discontinuities of any kind.