Fixed-Time Consensus Multi-Agent Systems Based Speed Coordination Control for Multiple Permanent Magnet Synchronous Motors

For modern complex industrial production processes, the speed synchronization control precision of multi-motor speed regulation systems is an extremely critical performance indicator. Therefore, this paper proposes a concept of fixed-time multi-agent consistency for the speed-coordinated control of multiple permanent magnet synchronous motors (multi-PMSMs). Multi-agent systems (MASs) have advantages such as flexibility, reliability, and strong self-organizing capabilities. Considering the inherent similarity between consensus control of MASs and coordinated control of multi-motor speed, each motor system can be viewed as a MAS. Graph theory describes agent communication, and a fixed-time consensus protocol is designed. Meanwhile, a fixed-time sliding mode observer is utilized to estimate disturbances and introduced into the consensus protocol, thereby obtaining the desired q-axis current. Then, within the framework of the field-oriented control, a fixed-time complementary sliding mode current controller is designed to track the q-axis reference current. The fixed-time convergence of both the controller and observer is proven using Lyapunov functions regardless of the initial state of the system. On the experimental platform with three PMSMs, the proposed control algorithm is validated and compared with the traditional deviation coupling control (DCC) algorithm through experiments involving speed-up and speed-down, load increase and decrease, and forward and reverse rotation. The speed-up and speed-down experiments indicate that the proposed control algorithm can accurately track the given speed. The transition process is relatively smooth without significant overshoot. During the steady-state process, the chattering amplitude of the proposed control algorithm is around 3 r/min, which is significantly lower than the approximately 5 r/min of the traditional DCC algorithm. The load increase and decrease experiments show that when load disturbances occur, the proposed control algorithm can restore the speed to the set value within a short time. Because an observer is designed to estimate and compensate for disturbances, the impact of load disturbances on the multi-motor speed regulation system is reduced. When the speed of one motor changes, the speeds of the other motors are correspondingly adjusted, reducing the system's synchronization error. When a sudden load disturbance of the same magnitude is applied, the proposed control algorithm results in a speed increase of 10 r/min, which is lower than the 20 r/min increase observed with the traditional DCC algorithm. The forward and reverse rotation experiments show that the proposed control algorithm does not exhibit significant overshoot. During the reverse rotation process, it transitions more smoothly than the traditional DCC algorithm. The following conclusions can be drawn. (1) This paper treats the multi-motor speed regulation system as a MAS, transforming the problem of coordinated speed control of multiple motors into a consensus problem in MAS. (2) A fixed-time consensus protocol is designed. A fixed-time sliding mode observer estimates and compensates for disturbances, thereby obtaining the desired q-axis current. (3) Comparative experiments verify the feasibility and robustness of the proposed algorithm. © 2024 China Machine Press. All rights reserved.