Studies on the effect of filtering, digitization, and computationalgorithm on the ABC-DQ current transformation in PWM inverter drivesystem

In the automotive industry, PWM inverter controlled drive systems find extensive applications in electric vehicles and other motion control systems. A PWM inverter controlled three-phase brushless synchronous motor drive requires a microprocessor based controller to implement the control algorithms. The practical implementation of the control algorithms sometimes calls for the use of lookup tables involving discretized quantities. All these processes and the devices introduce nonidealities and errors in the drive system. Of particular importance in such a system is the ABC-DQ current transformations when vector control is implemented. In automotive applications, the emphasis is to design and realize accurate motion control systems in the most economic manner possible. Hence the effects of filtering, digitization, quantization, and digital computation algorithms and the accompanying inaccuracies introduced by them during the ABC-DQ current transformation in PWM drive system have to be dealt with in a careful manner for an optimum and economic choice of system design to be possible. Some of these aspects are discussed in this paper. The studies lead to a better understanding of the importance of various parameters of power electronics systems and in turn contribute towards the proper selection of parameters and therefore help the design process