Improved power regenerative controls by using thyristor rectifier bridge of voltage source inverter and a switching transistor

Techniques for the regenerative control of a voltage source inverter are described. In these techniques, the thyristor rectifier bridge is used for regeneration through a DC reactor or a capacitor. The first method of regenerative control uses a pulse-width modulation (PWM) strategy in which the polarity of the sawtooth carrier waveforms are reversed alternately every 60 degrees in order to reduce the harmonics of output waveforms. The second method uses a modified Cuk converter technique for regeneration. The output current of the Cuk converter is shown to have a zero ripple. A frequency analysis method using a switching function is proposed and applied to the PWM current.<>