A terminal sliding mode control method based on nonlinear disturbance observer is investigated to realize the speed and current tracking control for PMSM drive system in this paper. The proposed method adopts the speed-current single-loop control structure instead of the traditional cascade control in the vector control of PMSM. Firstly, considering the nonlinear and the coupling characteristic, a single-loop terminal sliding mode controller is designed for PMSM drive system through feedback linearization technology. This method can make the motor speed and current reach the reference value in finite time, which can realize the fast transient response. Although the sliding mode control is less sensitive to parameter uncertainties and external disturbance, it may produce a large switching gain, which may cause the undesired chattering. Meanwhile, the sliding mode control cannot keep the property of invariance in the presence of unmatched uncertainties. Then, a nonlinear disturbance observer is proposed to the estimate the lump disturbance, which is used in the feed-forward compensation control. Thus, a composite control scheme is developed for the PMSM drive system. The results show that the motor control system based on the proposed method has good speed and current tracking performance and strong robustness.
- PMSM drive
- Terminal sliding mode control
- Feedback linearization
- Nonlinear disturbance observer
Figure 1: Block Diagram Of PMSM Control System
EXPECTED SIMULATION RESULTS:
Figure 2: The Motor Response Waveforms Of The Proposed Method: (A) Motor Speed (B) Dq-Axes Current (C) Phase Current
Figure 3: The Speed Waveforms Of Three Methods: (A) The Speed When The Motor Starts (B) The Speed With Load Disturbance
Figure 4: The Motor Waveforms With The Parameter Disturbance. (A) Motor Speed (B) Dq-Axes Current
Figure 5: The Contrastive Results With The Common Sliding Mode Control Method. (A) D-Axes Current (B) Q-Axes Current
In this paper, a novel control method based on terminal sliding mode control through feedback linearization technology has been studied for PMSM drive system. The controller adopts the speed-current single-loop structure, which has the fast transient response. With the designed terminal sliding mode controller, the speed and current stabilizing control is achieved. Then, considering the lump disturbance in the drive system, a nonlinear disturbance observer is designed to deal with the mismatched disturbance, and it is used for the feed-forward compensation, and the robustness is improved effectively. Simulation results have proved that the controller has good robust performance and speed tracking performance under various conditions. But the speed and current control problems in the flux-weakening control areas are not considered at present, which will be the future research emphases.
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