Accurate temperature prediction is vital for the canned permanent magnet synchronous motor (CPMSM) used in the vacuum pump, as it experiences severe heating. In this paper, a novel motor temperature calculation method is proposed, which takes into account the temperature impact on the heat transfer capacity. In contrast to existing electromagnetic-thermal coupled calculation methods, which solely address the temperature effect on the motor electromagnetic field, the proposed method comprehensively considers its impact on motor losses, permanent magnet magnetic properties, thermal conductivity, and heat dissipation ability of motor components, resulting in a motor temperature simulation that closely resembles the actual physical process. To verify the reliability of the proposed temperature calculation method, a 1.5 kW CPMSM was chosen as the research subject. The method was used to analyze the temperature distribution characteristics of the motor and assess the impact of ambient temperature on motor temperature rise. Furthermore, a prototype was fabricated, and an experimental platform was established to test the motor temperature. The results demonstrate good agreement between the calculated results obtained using the proposed method and the experimental data. This research not only provides a theoretical foundation for optimizing the design of the CPMSM but also provides valuable insights into its operational safety and reliability.

When the traditional multi-motor speed synchronous control strategy is applied to the vacuum pump system, it is prone to the drawbacks of large synchronization error. In this paper, a simplified mathematical model of the motor for a vacuum pump is established and the transfer function is introduced, which weakens the multivariable, strong coupling and nonlinear characteristics of the motor system. According to the basic principle of the relative coupling control strategy, the neural network Proportion Integration Differentiation (PID) is introduced as a speed compensator in this system. It effectively improves the synchronization and anti-interference ability of the multi motor.