Voltage regulation in induction machines with multiple stator windings by zero sequence harmonic control

We have investigated a method to regulate the voltages in the secondary windings of an induction machine stator with multiple windings. By introducing one or more triple-n harmonics in a three-phase machine, the rectified output voltage of one or more grounded-wye windings can be controlled and regulated. Voltage regulation is achieved through triple-n harmonic current injection, so there is no net torque on the rotor, decoupling voltage regulation from drive. We demonstrate and analyze voltage control in a custom wound induction machine by the addition of third harmonic to the inverter drive waveform. The rectified output voltage depends not only on the amplitude, but also on the phase of the third harmonic. The ability to orthogonally control voltage is particularly important in applications where the machine is used as a generator, motor and/or power converter at the same time