Current-Clamped, Modified Series Resonant DC-Link Power Converter and Control Strategies

A new AC/AC power converter topology, in which all the switches perform soft switching to reduce switching losses is proposed. The topology enables conduction-period control of individual current pulses, whereby PWM has been achieved. The scheme implements current peak (resonant) limiting by a simple diode clamp. Improved switch utilization (voltage. current) and reduced part-count could be cited as the merits of the circuit over the previous soft-switched, current-sourced AC/AC configurations. Moreover a simple controller, that generates “PWM current controlled, AC output voltages” is introduced, and experimental results are presented. In the scheme an indirect current feed-forward scheme which makes the system robust is introduced; scheme results in smooth controllable motor currents. Therefore, its applicability for a V/F drive is highlighted. For cases, where PWM is not possible, an alternative, current-controlled voltage-synthesizing method is introduced and simulation results are presented.