Speed-dynamic-decoupled Discrete Current Control Using Robust Pole Assignment for PMSM System with Low Inertia

The current model of permanent magnetic synchronous motor is commonly described as a first-order inductance-resistance system. Based on the first-order model, proportional-integral control with feedforward is widely utilized in practice. However, for motors with low inertia and high speed, the condition that the cross-coupling can be neglected or thoroughly compensated is no longer satisfied, leading to deviation of desired poles. The use of measurement low-pass filter (LPF) in feedforward introduces attenuation and deteriorates control effects as well. Therefore, the current model is reconstructed as a second-order system, and a speed-dynamic-decoupled discrete current control algorithm is proposed for better dynamic performance. Feedforward is not required so the LPF attenuation is prevented. By design with the re-modelled expression in discrete domain, expected bandwidth is obtained with higher accuracy. Finally, the effectiveness of proposed method is validated by simulation results.