Closed loop control of a symmetrical multipulse modulated single-phase bi-directional AC regulator feeding an inductive load

Single-phase topology of the bi-directional a.c. chopper with power MOSFET embedded discrete component four-quadrant switch (4QSW) realizations that operate in a high frequency chopping mode is used to implement the symmetrical multipulse modulation (SMM) technique that provides ac power control. The technique involves generation of several equidistant pulses per half cycle (M) and control of their duty cycle (δ) that are necessary for gate control of the 4QSWs and regulation of the fundamental output voltage magnitude. The output voltage magnitude and its harmonic profile are dependent on the values of M and δ. In this paper a novel practical closed loop feedback based analog-digital control is implemented and presented that provides SMM compliant pulses that can be manipulated for M and δ. Relevant experimental results are furnished to demonstrate the efficacy of the proposed control.