新一代高速动车组列车采用永磁同步牵引系统，由于运行工况恶劣会导致机械位置传感器故障进而造成列车限速、紧急制动等问题，而无位置传感器控制可以从根本上消除这一安全隐患。动车组永磁牵引电机需要长时间高速运行，要求采用方波调制进行电机弱磁控制，驱动系统固有的低开关频率及电压幅值受限的特点加大了转子位置估计难度。本项目针对方波弱磁的工况特性，拟开展考虑低次谐波及转矩脉动抑制的无位置传感器闭环延时补偿模型研究；结合实际的牵引系统转矩特性曲线，获取动态弱磁性能扰动因素对估计转子位置的影响机理；在此基础上，以提升位置观测器抗扰动性及动态弱磁电流控制精度为目标，获取基于基波电流观测、多参数误差补偿及弱磁指令电流二次规划的高速无位置传感器协同优化控制策略。研究结果可提高动车组永磁牵引系统方波弱磁区的转子位置估计精度，提升系统可靠性，为解决一类轨道交通用永磁同步电机高速无位置传感器控制提供参考。

Electric-multiple-units (EMU) traction system employing permanent magnet synchronous machine (PMSM) serves as the electrical drive core in the next generation train and the fault of position sensor during operation results in potential risk, which needs to be solved. Therefore, sensorless control strategy is essential for its safety operation. With the further increase of the maximum speed, EMU PMSM drive system operates usually in flux-weakening (FW)-based square-wave modulation mode where low switching frequency and output voltage limitation exist. All above characteristics bring extra challenge to the design of sensorless control strategy for such system. Aiming at the high harmonic noise interference and large torque ripple in square-wave condition, this project intends to carry out research on sensorless closed-loop delay compensation model based on the analysis of low-order harmonic characteristics, and the dq-currents coupling can be reduced. On this basis, combined with the torque characteristic curve of actual traction system, the influence mechanism of the dynamic FW performance disturbance factors on the estimated rotor position is obtained. Finally, during the process of position observer modeling and closed-loop control, fundamental current observation, multi-parameter error compensation and secondary programming of FW command currents are collaboratively optimized with the goal of improving the position observer anti-disturbance and the dynamic FW current control accuracy, then a sensorless control strategy suitable for FW-based square-wave condition is proposed. The research results of this project are beneficial for a category PMSM drive application with high-power that needs sensorless control technique.