Minimization of Torque Ripple in Dual Inverter Fed High-Power Wound Rotor Induction Motor Drive

Dual inverter fed wound rotor induction motor (DIWRIM) has gained popularity in various medium voltage high power industrial motor drive applications. To cope with high switching energy losses in voltage source inverters, switching frequency <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(f_{sw})$</tex> is restricted below <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$750Hz$</tex>. This results into high distortions on motor line currents which leads to high peak-peak ripple on electromagnetic torque. This paper proposes a carrier interleaving based technique for minimization of peak-peak torque ripple in DI-WRIM drive. The motor drive is operated with rotor flux oriented (RFO) and V/F control technique from stator and rotor sides, respectively. Both stator and rotor VSIs are operated with synchronized sine-triangle (SST) pulse width modulation (PWM) techniques having same pulse numbers. Optimized interleaving angle is determined and proposed for minimization of peak-peak torque ripple under full-load condition over complete range of fundamental frequency. Performance of motor drive is validated in terms of stator and rotor side currents under zero and optimal interleaving angles. Peak-peak torque is also computed under no- and half- load conditions at different interleaving angles to confirm the validity of proposed optimal interleaving angle. A <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$250kW, 400V, 50Hz$</tex> 4-pole, 1: 1, WRIM is used for validation of theoretical findings through simulations.