Abstract
Conventional predictive direct torque control (PDTC) of permanent magnet synchronous generators (PMSGs) with weighting factors suffers from extensive calculation burden and weighting factor tuning work. This paper proposes three predictive direct torque control techniques for PMSGs without weighting factors. The first proposed control strategy is based on the torque and reactive torque. Reactive torque has the same order of magnitude as torque, which eliminates the need of weighting factor in the cost function. The second proposed control strategy is based on estimating the q-axis reference current from the demanded torque and setting the d-axis reference current to zero, which achieves the maximum torque per ampere (MTPA) operation. Then, according to the deadbeat principle the reference voltage vector (VV) is directly computed from the reference current vector. The cost function design for this strategy includes only the reference voltage vector and the candidates one. The third proposed method is based on two separate cost functions, one is for the torque and another is for d-axis current. The proposed three control strategies eliminates the need of weighting factors and therefore, no tuning work is required.