As the power source of the robotic manipulators, the motors inside the joint servo systems generally start with a load directly and cannot execute position calibration due to the operating conditions. Therefore, the commonly used position acquisition scheme is the Hall position sensor during motor start-up. However, this scheme cannot start the motor with the maximum starting torque, as the Hall position sensor only provides the present sector of the motor rather than the precise angle. The traditional processing method utilizes a square-wave voltage to start up or take the middle value of the Hall sector as the angle input to the motor drive algorithm, thereby obtaining a large torque across the entire angle range of the Hall sector. These methods are simple but lose some torque in the event of a significant deviation in the position estimation.

This paper proposes a quick-startup method for surface-mounted permanent magnet synchronous motors (SPMSMs) based on a Hall position sensor. Firstly, the start-up process of different curves of random initial angles is analyzed. The deviation between the actual rotor position and the imprecise estimated position decreases the starting torque, as the Hall sector spans an angle range of 60°. Under these conditions, combined with the field-oriented control (FOC) algorithm and the maximum torque per ampere (MTPA) strategy, the quick start-up method is proposed, and the critical start-up curve parameters are numerically calculated. Although the initial and precise angles during the start-up process are not available, the proposed curve can be close to the average locus to a great extent.

The simulation and an experiment are conducted using an actual servo motor under different initial angles. The results show that when the initial rotor position is close to the minimum angle of the Hall sector, the proposed method exhibits a pronounced acceleration effect. Due to the short stroke, although the position tracking of the proposed method is slightly behind the traditional method, the time difference is negligible when the initial position approaches the maximum angle. Combined with the average start-up time of the entire initial angle in the Hall sector, the proposed method can effectively reduce the average start-up time.

A quick start-up method for SPMSM based on a Hall position sensor is proposed. In the conventional control method, the maximum starting torque and the minimum statistical value of the start-up time cannot be achieved over the entire range of initial angles. Therefore, the novel position curve is designed to improve the start-up time for small initial angles in each Hall sector while considering the start-up process at other angles. Statistical analysis has demonstrated a significant reduction in the start-up time expectation of the entire initial rotor positions. The method optimizes the torque reduction problem during the start-up process, which is caused by imprecise positioning in the first Hall sector. Moreover, the ease of transplantation allows the method to be applied to various motor drive algorithms.