Variable frequency variable duty cycle operation of the controlled capacitor charging (CCC) type inverter

The controlled capacitor charging (CCC) type inverter uses a simple L-C network, where the capacitor (C) that is connected across the load is charged through an inductor (L) connected in series with the load. The charging in such an inverter has to take place in a controlled manner to produce a desired sinusoidal waveform at the output. This paper presents a variable frequency variable duty cycle based charging technique to keep the output voltage within a hysteresis band, while achieving zero-current switching for every pulse at turn-on. The output voltage across the capacitor and the current through the inductor are fed back to the control circuit. An appropriate logic in the controller determines the width of each individual pulse, as well as the frequency of pulses. Extensive simulations in PSPICE have been carried out. A prototype inverter has been fabricated in the laboratory. Excellent correlation between the simulation and experimental results validated the proposed control technique