Reduced-Order Extended Observer and Correction Discretization Method for High-Speed Permanent Magnet Synchronous Motor with LCL Filter

The Forward Euler method is well known for its simplicity and ease of implementation in Permanent Magnet Synchronous Motor (PMSM) controls. However, it introduces significant errors, which becomes more severe when establishing the discrete-time model of a high-order system for a high-speed PMSM with LCL filter. Traditional discrete methods, which have smaller errors, are too complex and difficult to apply in high-speed systems. To address these issues, this paper proposes a sensorless control method for surface-mounted high-speed PMSM with LCL filter based on a predictive correction Runge-Kutta (PCRK) discrete method. High-precision extended Luenberger observer and strongly robust sliding mode observer are established to estimate motor side currents and rotor position. PCRK is proposed to reduce discretization errors and computational load. Implicit equation issues in numerical solutions are eliminated through predictive-corrective steps to implement the algorithm in digital circuits. Several simulations and experiments are conducted in three methods-the traditional Euler method, the bilinear transform method, and the proposed method. Comparisons demonstrate that the proposed method has good rotor position estimation performance and a wide pole configuration range in sensorless control of HSPMSM with LCL filter.