Research On Stability Regions And Speed Response Improvement Based On PMSM Speed-regulation System Under Vector Control

The vector control system based on PMSM is widely used. A comprehensive consideration of stability, dynamic and static characteristics is necessary when designing a high performance AC speed-regulation system. In this article, stability and dynamic performance are focused and stable regions of PI controllers are shown. Besides, a improved time-minimum controller, which improves the speed dynamic response and strengthens system anti-load disturbance ability, is put forward instead of traditional PI controller in the speed loop.Firstly, this paper aims to get stable regions of PI parameters and sampling time of PMSM speed regulation system according to the mathematic model in frequency domain and discrete z domain. Based on the complex vector model for PMSM, quantitative analysis of the effect of dq axis coupling voltage on system stability is deduced and the correctness of voltage feedforward decoupling method is verified by ploting system zeros and poles position. In order to improve speed rapidity, stable regions are optimized by designing the relation of PI parameters according to zero-polecancellation and extending the middle frequency bandwidth of Bode Plot. Stability analysis and regions are validated by Simulation, which provides theoretical basis for safe and stable operation of system.Then, a improved time-minimum controller of speed loop is proposed in this paper. The principle and design of this new speed control system which consists of reduced-order observer and nonlinear function controller are introduced in detail. Theoretical analysis and simulation results show that compared with PI controller, the speed step response of the new system with improved time-minimal controller has no overshot, shorter response time and stronger anti-disturbance ability.Finally, experiment is carried out on a 1.5kw power PMSM. Experiments show the rationality and correctness for the theoretic analysis of system stability regions, PI parameters and sampling periods. PI parameter values have great influence on system dynamic response. The improved time-minimum controller which causes better dynamic response than PI is of simple principle. Additionally, system anti-disturbance ability is improved with the compensation of torque current by the reduced-order load torque observer in feedback loop. The experimental results show the viability and superiority of the improved time-minimal speed control method.