Hybrid Space Vector Modulation Scheme for Dual Inverter Fed Open End Winding Induction Motor Drive for Improved Harmonic Distortion

In this paper, a hybrid space vector modulation (SVM) scheme with reduced harmonic ripple for a dual inverter fed open end winding induction motor (OEWIM) for various fundamental frequencies and operating power factors is presented. Various SVM methods are compared based on the harmonic distortion to identify the zones of superior performance and to propose a hybrid SVM for the entire operating range. In dual inverter fed OEWIM drives, the reference voltage can be synthesized by level shifted carrier based SVM method or by using decoupled SVM method. In the decoupled SVM method, each inverter can be switched independently of each other, thus different SVM techniques can be applied in the individual inverter. This paper exploits the above possibility and analyses combinations of conventional SVM and bus clamping SVM applied to the individual inverters in terms of their harmonic performance. Harmonic performance of various SVM techniques are compared using the concept of stator current ripple and is analysed for various fundamental frequencies and operating power factors to find an optimum method over the entire modulation range. The SVM methods are analysed using MATLAB Simulink by operating an induction motor drive under open-loop volts per hertz control scheme with fixed number of samples per fundamental frequency.