Accurate Discrete-Time Modeling for Improved Torque Control Accuracy for Induction Machine Drives at Very Low Sampling-to-Fundamental Frequency Ratios

摘要

Operations at low sampling-to-fundamental frequency (S2F)ratios of induction machines are required for high-power or high-speed applications. The traditional indirect field-oriented control is open-loop control on torque, which is sensitive to machine parameters and degrades at low S2F ratios. Deadbeat-direct torque and flux control (DB-DTFC)is closed-loop control on torque but also degrades at low S2F ratios with discrete-time approximations. This paper presents accurate discrete-time modeling for the flux and current observer and the deadbeat controller used in DB-DTFC. Experimental results show that the torque control accuracy is significantly improved even at very low S2F ratios.