Research On Turning Algorithm Of Current Control Parameters For Motor Driver

Lithography machine is the most important equipment in the processing of integrated circuits.In order to improve the production efficiency of the lithography machine,it is necessary to improve the speed,acceleration and the precision performance of the workpiece of the lithography machine.The workpiece is driven by the permanent magnet synchronous motor.In order to improve its performance,we can improve it from both the motor and drive.Some improvement measures have been done from the hardware of the permanent magnet synchronous motor and PWM driver so far,but the effect is limited,we also need to improve the motor coil current response speed and stability through the driver current control to improve the performance of the workpiece;The PWM driver control system uses the classical three-loop control structure,which is the position loop,the speed loop and the current loop from outside to inside.The current loop mainly controls the current of the motor,and it is controlled by the PID controller.To improve the performance of the workpiece,it is necessary to study the current control parameter setting algorithm in the current loop.The traditional PID parameter tuning algorithm mainly aims at some theoretical indicators,such as the optimal zero pole,the minimum error,and so on.But these indicators do not take into account the actual drive output limit,so the parameters obtained by these indexes often can not achieve the desired target in the actual application process.In this paper,the current control target would consider the actual output limit of the driver,ensuring that the theoretical output of the current controller does not exceed the limit amplitude when the current loop of the driver reacts to the current command,setting the shortest time of the current in the motor coil reaching the maximum allowable current as the target of the current control parameters turning when the motor running at the fastest speed,and guaranteeing that the response speed of the current in the coil can reach the target regardless of the running state of the motor.For the goal,this paper presents the corresponding current control parameter tuning ideas.Firstly,the transfer function model of the controlled object in the current loop is obtained through the open loop model identification of the current loop.Secondly,the open-loop frequency characteristic of the current loop is obtained,and we can adjust the open-loop frequency characteristic curve to to a satisfactory form according to the relationship between the open-loop frequency index and the closed-loop stability and the response speed performance,solving the current controller parameters through the open-loop through the frequency point at the same time.Finally,due to some parameters obtained by the estimation in the process of parameter calculation,the obtained parameters may not be optimal,so the parameters need to be optimized by the genetic algorithm in the neighborhood of the parameters to ensure that the resulting parameters make the current loop system perform optimally.Finally,by setting up the linear motor servo drive experiment platform,using the proposed parameter tuning method to set and optimize the drive current control parameters,the parameters of the tuning and the optimized parameters are used for the current loop step response test of the motor under static and motion respectively.The test results show that the parameters before and after optimization can achieve the target of current loop performance,checking the feasibility of the proposed driver current control parameter setting algorithm.