Research On The 2D Digital Servo Valve Controller Based On TMS320F28335

The 2D digital servo valve use the servo screw mechanism to set the pilot level and the main spool into a single spool,which makes the servo valve lots advantages,such as simple structure,fast frequency response,good anti-pollution capability and so on.The electro-mechanical converter,as the core part of the 2D digital servo valve,largely determines the performance of the 2D digital servo valve.So how to improve the performance of the electric-mechanical converters,has a very important significance to improve the performance of the 2D digital servo valve.The research object of this paper is the 6 diameter 2D digital servo valve and its controller.The electric-mechanical converter of the 2D digital servo valve is a two-phase hybrid stepper motor.It has many advantages,such as high natural frequency,direct digital control,ect.But there are lots of shortcomings,such as low resolution and easy to get out of step,ect.In order to solve the above problems,this paper proposes the position and current double closed-loop control theory,which is based on the current synchronization control,to make the motor rotor can locate in any position without out of step.TMS320F28335,as the master control chip of the controller,has lots of advantages,such as high compute rate,high data processing capability,good float compute performance,ect.DRV8432,as the motor driver chip,has many advantages,such as strong driving ability,small package and so on,which is very suitable for motor control application.So this paper use TMS320F28335 as the master chip and DRV8432 as the motor driver chip to complete the design of the controller and improve the control performance of the controller.The design of the servo valve controller,not only reduces the volume of the controller,enhance the integration and improve the performance of the controller,but also improves the dynamic and static characteristics of the electro-mechanical converter and the 2D digital servo.The specific research contents and achievements are as follows:1.The structure and working principle of the 2D digital servo valve body are studied.The mathematical model is established by mathematical analysis.The dynamic and static characteristics of the mechanical part and the influence of the structural parameters on the performance are obtained through the tool of MATLAB.2.The classification and the working principle of the electric-mechanical converter of the 2D digital servo valve are studied.The mathematical model of the two-phase hybrid stepping motor is established.The advantages and disadvantages of subdivision control are analyzed,and the idea of current synchronization control is put forward.Based on the current synchronization control,the position current double closed-loop control is proposed to make the motor rotor to fast locate on any position without get out of step,which improves the performance of the rotor in response speed and control precision.By using the current synchronization control strategy and the current and position double closed loop strategy,the mathematical model is established and simulated in Simulink.The bandwidth of the electric-mechanical converter is 435 Hz,the step response rise time is 3.2ms.3.In this paper,TMS320F28335 is used as the master chip,and the full-bridge driver chip DRV8432 is used to drive the step motor,the ACS712 current sensor is used to detect two-phase current.The hardware of the controller is built by these chips,which improves the performance of the controller.The design of the servo valve controller,reduces the volume of the controller,enhance the integration and improve the reliability of the controller.The software programming is completed in the CCS environment,which includes the main program and the main interrupt subroutine software programming.After the design of the software,the design of the controller is completed.The experimental platform for the electro-mechanical converters is built.The experimental results show that the dynamic and static characteristics are good under the control of the controller.The hysteresis is 2.5%,the non-linearity is 1.6%,the bandwidth is 250 Hz,the rise time of the step response is 5.3ms.4.The experimental platform for the 2D digital servo valve is built.The experimental results show that the hysteresis loop is 4.96%,the non-linearity is 3.37%,the null position leakage of pilot stage is 4.8L/min,the bandwidth is 180 Hz,the rises time of the step response is 6.5ms.The 2D digital servo valve has good dynamic and static characteristics.