A no-disturbance startup scheme for PMSM speed loop with auto-tuned current loop

Incremental encoder is commonly used for identifying the rotor position of a permanent-magnet synchronous motor (PMSM) in industrial applications. However, initial rotor position error exists when the conventional UVW algorithm is applied, thus uncertain disturbance occurs when Z-pulse correcting. In order to eliminate the preliminary identifying error and obtain the accurate rotor position immediately, a practical and efficient algorithm is proposed. In the proposed initial rotor identifying algorithm, the proper current vector is selected for each sector, and the accurate rotor position can be obtained in a movement of 60 electrical degrees in the worst case. A current loop auto-tuning method based on parameter estimation and frequency domain design is also proposed to construct a no-disturbance startup PMSM servo system for verifying the benefit of the proposed initial rotor identifying algorithm. Finally, comparative experiments between the conventional UVW algorithm and proposed initial rotor identifying algorithm in no-load and load case were conducted in TMS320F28335-based platform, which demonstrates the correctness and effectiveness of the proposed algorithms.