A novel quasi-resonant inverter for high performance induction motor drives

A novel quasi-resonant inverter is proposed for a high performance induction motor drive. With the exception of auxiliary switch in the resonant link, all other devices in the resonant link and inverter are operated under zero-voltage switching (ZVS). The auxiliary switch is turned on under zero-current switching (ZCS), but turned off hard. The DC link voltage is clamped to source voltage. The quasi-resonant inverter-fed induction motor is operated under direct torque control (DTC) scheme. The d-q model of the complete scheme is formulated and analyzed by SABER simulator. The simulation is extended with a robust, reduced order stator flux observer. Both the schemes with and without observer have been implemented on a laboratory-sized experimental setup. A comparison of simulation and experimental results under identical operating conditions reveals good agreement.