Redundant Sampling and Drive Control Strategy Based on Phase Current Reconstruction of Permanent Magnet Motor

A discussion of two methods for reconstructing the phase currents of permanent magnet synchronous motors is presented. These approaches are based on the sampling of driver DC bus currents and single-phase currents, respectively. The former is known as three-phase current reconstruction based on driver DC bus current sampling, while the latter is referred to as second-order generalized integrator(SOGI) three-phase current reconstruction based on single-phase current sampling. Since both methods are able to provide three-phase current feedback for motor drive control independently, the reliability of the current feedback of the drive system is improved. The performance of the two reconstruction methods is compared by simulation and experiment. It is found that the transient performance of bus current reconstructed phase current is better and the response is fast, but due to the effect of switching timing, the reconstructed current can be observed to be significantly noisy; on the contrary, the steady-state performance of single-phase current SOGI phase-locked loop reconstructed current is better, the phase current is smooth and stable, but the transient performance is poorer, and the obvious current amplitude change hysteresis can be observed. Therefore, a fusion control strategy that combines the advantages of the SOGI three-phase current reconstruction methods for DC bus current sampling and single-phase current sampling is proposed. Through a dynamic weight adjustment mechanism, the strategy is able to flexibly adjust the degree of dependence of the drive controller on the two current reconstruction feedbacks according to different operating states. The fusion control strategy is verified by simulation and experiment, and shows good performance under different operating conditions, providing a new scheme in the field of motor drive control.