CURRENT-CLAMPED, MODIFIED SERIES RESONANT DC-LINK POWER CONVERTER FORA GENERAL-PURPOSE INDUCTION-MOTOR DRIVE

A new ac/ac power converter topology, in which all the switches operat e in a resonant fashion to reduce switching losses, is proposed. The t opology enables conduction-period control of individual current pulses , whereby pulse-width modulation (PWM) could be achieved to a fair deg ree of accuracy with the associated controller. The scheme implements current peak (resonant) limiting by a simple diode clamp. Improved swi tch utilization (voltage x current) and reduced part-count could be ci ted as the merits of the circuit over the previous soft-switched curre nt-sourced ac/ac configurations. It is experimentally verified that th e output PWM controller could be used to implement constant V/F operat ion, and the results are presented. In-depth design criteria for the t opology that gives optimized voltage stresses are presented. A charge- based, line current feed-forward, mode-controller is introduced at the input and digitally verified. Feasibility of the simultaneous control over both input power-factor and smooth input-output line currents ar e studied and the digital verification is presented.