Novel topologies of pulse-width modulated (PWM) AC choppers for single
-phase and three-phase systems are proposed for buck, boost and buck-b
oost types. A PWM AC chopper has important advantages compared with th
e phase-controlled AC controller using thyristors. The AC chopper has
sinusoidal current waveforms, better power factor, faster dynamics, an
d smaller input/output filter. In a recent improved topology for AC ch
oppers, an RC bypass snubber is used for minimising high-voltage spike
s during the dead time in the gating signals of complementary switches
. In the proposed topologies the commutation problem causing high-volt
age spikes is resolved by intelligent gate-switching patterns using in
formation from the input/output voltage. These switching patterns prov
ide a current path for all operation snubbers. power loss are eliminat
ed, the efficiency of the chopper is increased. Thus, advantages of th
e include increased power harmonic input current, fast dynamics, high
efficiency, high reliability, high power capacity, and small size of t
he passive filter. The paper describes the operational principle and a
nalysis of the proposed topologies. Experimental results show that the
proposed topologies give good perfomance for AC choppers.