Research on Temperature and Speed Cascade Control Method of Liquid Viscous Drive Based on Variable Ratio Model

For the liquid viscous-driven cooling fan system, a cascade control strategy including inner-loop speed feedback and outer-loop temperature feedback is proposed. The inner-loop control system is based on the variable ratio model to achieve the speed regulation of the liquid viscous-driven fan; the outer-loop control system is responsible for regulating the target speed of the fan. The experimental results show that the MPC temperature control algorithm based on model identification can provide a suitable target speed, and the speed control algorithm based on the variable ratio model compensation can reduce the dead zone of the system, expand the effective control interval, weaken the influence of hysteresis nonlinearity and improve the speed tracking accuracy, the hysteresis of the system is reduced from 40%-50% under open-loop control to 15% under feedforward compensated closed-loop control; the turn-point lag time is less than 1 s.