Adaptive Current Control for High-Efficiency Motor Drive Operation in Transients

To ensure efficient operation of synchronous motors (SMs), it is essential to apply techniques that minimize losses. In most control systems, the maximum torque per ampere (MTPA) control strategy is commonly used, as it offers a balance between simplicity and loss reduction. Developers typically focus on MTPA control during steady-state operation, which is the primary mode of most motor drives. However, in applications such as automotive systems and machine tools, motors often experience frequent transients, making it vital to incorporate MTPA control during these transients for optimal performance. This paper presents an algorithm designed to optimize current transients, aiming to guide the motor's current trajectory closer to the MTPA curve. Furthermore, considering that the Joule losses are proportional to squared currents, the proposed algorithm uses non-linear approximation, where approximation gains are proportional to squared currents. While the technique is inactive during steady-state operation, it becomes active when the control system detects a significant change in the current command and it dynamically modifies the gains of current controllers. When the transient is completed, the algorithm restores the original gains and deactivates. Experimental results demonstrate the feasibility of the proposed approach and show improved motor trajectories during transient operations.