A split-wound induction motor design to improve the reliability of PWM inverter drives

Induction-motor stator windings have been designed to protect the PWM (pulsewidth-modulated) inverter bridge against simultaneous-conduction fault currents. Rather than adding series inductance in each inverter leg, to control the fault currents, part of the induction motor´s primary leakage inductance performs the fault current control function. An extensive evaluation of this fault current control is given. The effects on the performance of a 4 kW two-pole squirrel cage induction motor illustrates protection and derating aspects. Torque and power derating factors are used to show that the motor output power, and torque, is traded off against the degree of fault protection. Experimental results for a 5 kW MOSFET inverter drive, are used to illustrate the variable-speed performance of the drive. The protection afforded is shown to increase with the motor power and voltage rating.<>