Synchronous Commutation Control of Doubly Salient Motor Drive With Adaptive Angle Optimization

Due to the strong nonlinearity of the commutation process of doubly salient motors fed by square-wave currents, it is difficult to establish accurate models and design an appropriate commutation control strategy to achieve satisfactory commutation performance. The synchronous commutation control method is proposed to improve commutation control. By introducing an additional angle loop to synchronize the zero crossings of the phase current and the alignment of the core poles, the commutation angle can be adaptively optimized without requiring the accurate model. Also presented is a vector control scheme during the commutation process to shape the trajectory of the current vector into a regular hexagon. Based on the linearized model of the commutation process, the digital control law to synchronize the zero crossings is designed with robustness considered. Finally, simulations and experiments were conducted. The results show less commutation torque loss with the method. Ultimately, the method provides a high torque-to-current ratio and low-torque ripple at a wide range of speeds.