Robust Repetitive Velocity Control Of Permanent Magnet Linear Synchronous Motor

Permanent magnet linear synchronous motor,which has the merits of high velocity,high precision and high efficiency,can convert electrical energy into mechanical energy directly.Nevertheless,linear motor’s direct drive structure will transfer various kinds of disturbances to motion controller directly without buffer and seriously affects system’s stability.In this paper,for solving the problem that linear motor’s current and velocity control systems are vulnerable to the influence of motor parameters’ changement,external disturbances,system transmission delay and other factors,a control method for current loop and velocity loop is put forward,which integrates robust compensation controller and delay compensator.Input term,integral term and first-order reference model’s inverse model are the constituents of robust compensation controller.Transmission delay model’s inverse model is used to offset system’s transmission delay in transmission delay compensation part.The adverse effect of modeling uncertainty,which is touched off by the difference between reference model and unknown actual system model,is cut down by robust compensation controller with delay compensation.The controller can also suppress the disturbance caused by dq axis coupling,friction,transmission delay and other factors.In view of the problem that the robust compensation controller can not effectively suppress the adverse effects of periodic disturbances on the velocity stability of linear motors,a repetitive controller is added to the velocity compensation controller with delay compensation to improve it to a velocity robust compensation repetitive controller.Velocity robust compensation repetitive controller can effectively restrain the negative impact of periodic disturbance caused by end effect and other factors on linear motor’s velocity stability.The control scheme put forward in this paper has a straightforward structure,which lets system’s output is equal to input in steady state.What’s more,while using this control scheme,there is no need to combine other control algorithms.Simulation and experiment results indicate that the influence of internal factors on current and velocity of linear motor,which contains transmission delay,end effect and external disturbances including friction and load,are effectively suppressed by proposed control scheme,while the system’s anti-interference performance,stability and robustness are improved.