Five-phase induction motor drives with DSP-based control system

This paper introduces two kinds of control schemes: vector control and direct torque control (DTC). These control schemes can be extensively applied to the operation of a five-phase induction motor using a fully digital implementation. Vector control of the five-phase induction motor not only achieves high drive performance, but also generates the desired nearly rectangular current waveforms and flux profile in the air-gap resulting in an improvement in air gap flux density and an increase of 10% in output torque. The DTC method has additional advantages when applied to multiphase, in this case a five-phase, induction motor. The five-phase inverter provides 32 space voltage vectors in comparison to 8 space voltage vectors provided by the three-phase inverter. Therefore, a more elaborate flux and torque control algorithm for the five-phase induction motor can be employed. Direct torque control of the five-phase induction motor reduces the amplitude of the ripples of both the stator flux and the torque, resulting in a more precise flux and torque control. A 32-b floating-point TMS320C32 digital signal processor (DSP) enables these two sophisticated control techniques to be conveniently implemented with high control precision. Experimental results show that an ideal control capability is obtained for both control methods when applied to the five-phase induction motor and further validates theoretical analysis.