Linear Quadratic Optimal PID Control In Brushless Direct Linear Motor

Brushless direct linear motor is a linear motor plant of converting electrical energy into mechanical energy without switching mechanism. It has many merits such as simple structure, on touch motor, low noise, high accuracy velocity, easy control and high reliability. It has been more and more widely applied in many fields. The linear brushless dc motor has developed mainstream of driving motor. This paper is devoted to the robust servo control of a linear brushless dc motor with uncertainties. The LBDCM is greatly affected by the uncertainties of the plant, which are composed of plant parameter variations, external load disturbances, and unmodified and nonlinear dynamics, because it is not equipped with auxiliary mechanisms such as gear or ball screws. Therefore, it is very important to quickly compensate these equivalent disturbances which directly impose on the mover of the BLDCLM. Because traditional LQ optimal control method does not make the system of uncertainties stable, so this paper proposed methods of modified LQ optimal control approach and robust L₂ control is proposed to suppress the uncertainties corrupting the motor.Linear quadratic optimal control and PID control are approaches that time-domain analysis is and frequency-domain analysis is the basic approach in designing control system and they have close relationship to each other. The paper presents a method for the PID dynamic compensation parameter of optimizing, which is obtained from design and optimization for linear quadratic optimal control system.Subsequently, Control method of robust L₂ is presented in this paper, it is applied in the BLDCLM set-point control. Robust L₂ control is a constant structure and parameter. When system is affected by uncertainties of plant, it can satisfy need. This is Robust L₂ control merit.And then the system is simulated with MATLAB software, analyzing the respond of position and velocity response curve in modified LQ optimal control and Robust L2 control method. In view of the result of simulation, the method of modified LQ optimal control is very effective for position regulation control and set-point control in the different loading condition. The results verified the validity of the scheme.