NEW CURRENT SOURCE INVERTERS WITH DC-SIDE COMMUTATION AND LOAD-SIDE ENERGY RECOVERY CIRCUIT

Two all-thyristor-type current source inverters (CSI's) with dc-side commutation and load-side energy recovery are proposed with analyses and explanations of the circuit operations. The inverters overcome most of the drawbacks of conventional CSI's-high device voltage stress, low operating frequency range, large commutation capacitance, etc.-by employing a simultaneous recovery and commutation concept. The new CSI's employ only one commutation capacitor and can be built with considerably low cost. The commutation energies are temporarily stored in a large dc capacitor and recovered to the load side, which makes the device voltage stress low and the efficiency high. Computer simulation results are given in brief comparison with the auto-sequentially commutated inverter. Finally, experimental results are shown for 5-hp induction motor drive.