Research on pump-HA motor speed control system based on switched PID control

Aiming to improve the control precision of pump-HA(high pressure automatic variables) motor speed control systems, the characteristic of HA motor displacement control mechanism is analyzed, and the mathematical model of pump-HA motor system is established. Taking the nonlinear character of the system, the system is approximated to a few of first order plus time delay processes, according to the working conditions. Parameters of the system models under different working conditions are identified by step response identification, PID parameters are tuned by a parameter tuning algorithm. A UKF state estimator is designed to estimate the load torque on the basis of the state space model established, then PID parameters are switched according to the desired speed and load torque. The research results indicate that switched PID control can ensure the system always has a good dynamic performance under different conditions and improve the control precision, making the system deal with various complex working conditions.