Keywords: controlled capacitor charging, CCC, PWM inverters, pulse width modulation, discontinuous conduction mode, DCM, simulation, feedback control
Design simulation and experimental evaluation of a three-phase controlled capacitor charging type inverter
This paper presents the design, simulation and experimental verification of a new three-phase pulse width modulated inverter. The inverter works on the principle of controlled capacitor charging, where a capacitor that is connected across the load is charged or discharged in a controlled manner to synthesise a desired waveform. The input to the inverter being a voltage source, an inductor is used in series with the capacitor to limit the charging/discharging current. High frequency pulses are used to fabricate the waveform and also to reduce the size of the inductor. A controller, taking a sinusoidal reference voltage signal and operating on a unique tracking logic, controls the switches in discontinuous conduction mode. The capacitor-voltage at the output and the inductor-current are fed-back to the controller. The inverter is able to track the reference-voltage satisfactorily to synthesise the output-voltage. The proposed inverter is first simulated in PSPICE. An experimental prototype is also fabricated in the laboratory. Excellent correlation of the simulation and experimental waveforms confirm the usefulness of the proposed inverter.