In 2020, China's motor ownership is about 2.95 billion kilowatts, and the annual power consumption account for more than 60% of the total social power consumption. Improving the motor operation efficiency will play an important role in achieving carbon peak and carbon neutrality. Based on the equivalent model of permanent magnet synchronous motor with iron loss, this paper proposed online identification of iron loss resistance based on model reference adaptive system (MRAS), then given current of d and q axes with the minimum sum of copper loss and iron loss is derived. Based on Simulink, the equivalent model of motor with iron loss is established, and the feasibility of the proposed method is verified by simulation. The simulation results show that compared with the traditional id=0 control method, the minimum loss control method proposed in this paper effectively reduces the loss in the motor operation, improves the efficiency, and has faster response, smaller overshoot, and better dynamic performance.