Dynamic Loss Minimization using Improved Deadbeat-Direct Torque and Flux Control for Interior Permanent Magnet Synchronous Machines

Direct torque control (DTC) has become a widely acceptable alternative to field oriented control (FOC). Deadbeat-direct torque and flux control (DB-DTFC) is a significant improvement over the classical DTC methods and provides the opportunities for fast torque control and dynamic loss minimization control. The existing high switching frequency DB-DTFC solution is based on approximate discrete time models. This paper presents a low switching frequency model so that even at low switching frequencies, proper DB-DTFC control can be achieved. The instantaneous dynamic loss model, which is a function of Volt-sec selection in each switching period, containing nonlinear effects such as minor hysteresis loops is theoretically derived and evaluated by both FEA simulation and experiments. With this calibrated dynamic loss model, deadbeat dynamic loss minimization control is implemented and integrated in DB-DTFC. Finally, the dynamic loss minimization control is evaluated experimentally and compared with the existing steady state loss minimization control.