This example shows a drive acting on the auxiliary winding of a single-phase synchronous machine.
H.Ouquelle and Louis-A.Dessaint (Ecole de technologie superieure, Montreal)
The motor's main winding is directly connected to the 110 V utility supply. The auxiliary winding is fed by a H-bridge IGBT inverter connected to a rectifier.
The reference values of the magnitude and phase of voltage applied to the auxiliary winding are computed by the Reference Voltage block . By varying the auxiliary winding voltage magnitude and phase, the torque ripples are alleviated at all operating points. The voltage control loop uses a proportional-integral-derivative (PID) controller.
Start the simulation. The machine starts at no load and then at t=1.0 sec, once the machine has reached its steady state, the load torque is increased to its nominal value (1 N.m) in 0.5 sec.
Observe that torque ripples are substantially mitigated at all operating points. Also observe the auxiliary and winding currents. These currents are in quadrature and their magnitude ratio is equal to the ratio N of number of turns of auxiliary and main windings.
 COLLINS, E.R., PUTTGEN, H.B., and SYLE, W.E.'Single-Phase Induction Motor Adjustable Speed Drive: Drive Phase Angle Control Of the Auxiliary Winding Supply'. IEEE® Industrial Application Society annual meeting conference records, pp.246-252