Steady state operation of a controlled hidden-link induction motor drive

The controlled operation of the naturally commutating hidden link power converter driving a cage induction motor is described. The motor is shunted by excitation capacitors such that the motor-capacitor lead operates at a leading power factor above 35 Hz. It is shown that, in the lagging power factor region, the drive yields acceptable performance for fan and viscous type loads, suggesting that the drive is applicable to variable frequency starting of high-power induction motor drives. The authors describe an experimental rig controlled by an 80C196 processor performing speed and current control. Current and voltage waveforms in the lagging and leading power factor regions are given