FPGA implementation of sensorless sliding mode observer with a novel rotation direction detection for PMSM drives

Abstract

This paper proposes an field programmable gate array (FPGA) implementation of a sensorless controller for surface mounted permanent magnet synchronous machines. Position and speed are both estimated by a sliding mode observer (SMO) which is based on the PMSM stator frame model. The sliding mode manifold is chosen on the real stator current trajetory. In the SMO, a sign function of current error in the feedback correction is adopted. The estimated speed and position are realized on an FPGA controller by COordinate Rotation Digital Computer (CORDIC) algorithm. Using model-based design, with the tools of MATLAB/Simulink and hardware description language coder, the whole control system is designed and implemented in a single FPGA chip. Dedicated hardware optimization algorithms such as pipeline and resource sharing are developed for the implementation as well. The sign function is realized by fully hardware with a relatively high switching frequency. Meanwhile, a fast and practical rotation direction detection method which is based on back electromotive force information is proposed. Experimental results show that the proposed FPGA implemented sensorless SMO for PMSM drives is robust and has high performance.