Research On Low-speed Closed-loop Control Strategy Of Automotive Electronic Water Pump Based On High-frequency Injection Algorith

Under the requirements of the new four modernizations of new energy vehicles,oems have higher and higher emission requirements for auto parts.At the same time,the national "dual carbon" target has put forward higher requirements for the efficiency of automotive power and heat dissipation system.The appearance of electronic water pump makes the automobile water pump and engine speed decouple,the water pump can achieve independent precise control,greatly improve the efficiency of the heat dissipation system.At present,electronic water pump has become a key component of automotive thermal management system,but under low speed conditions,the traditional open-loop control method can not solve the problem of large starting torque caused by low coolant temperature and high viscosity.In this paper,the low speed closed-loop control strategy of automotive electronic water pump is explored and studied in order to improve the low speed open-loop control of automotive electronic water pump.Firstly,the starting process of electronic water pump based on non-inductive permanent magnet synchronous motor(PMSM)is studied and analyzed.Due to the accuracy of rotor position estimation at low speed,the open-loop control method is mainly used for automotive electronic water pumps at low speed.The closed-loop control strategy applied to low speed conditions is mainly high-frequency injection algorithm.The principle of the algorithm is to use the salient pole effect of the motor to form a closed-loop control at low speed.However,at present,high-frequency injection methods are mostly used in high voltage(greater than 60V),high power(greater than1 k W)and high convexity ratio(greater than 1.3)PMSM occasions,and their applicability to low-voltage and low-power application scenarios studied in this paper has not been extensively studied and practiced.Secondly,the low-speed closed-loop control method of 24V/600 W automotive electronic water pump embedded permanent magnet synchronous motor(IPMSM)control system is studied and verified.In this paper,the model of traditional open loop control method is established and its steady-state performance and dynamic performance are simulated and verified.The simulation results show that the open-loop start strategy can not stabilize the load reduction.At the same time,three closed-loop control models of high frequency injection method are designed in this paper.The speed error,Angle error,phase current and torque fluctuation indexes are analyzed and verified by simulation from two aspects of steady and dynamic performance.It shows that high frequency square wave injection method can effectively improve the load reduction performance of PMSM under low speed conditions.Finally,a 24V/600W automotive electronic water pump control board is designed to verify the high frequency square wave injection method.The experimental results show that the low-speed closed-loop control method proposed in this paper can be used to solve the problem that the low-voltage,low-speed and low-salient ratio IPMSM open-loop control can not feedback the rotor position in real time,which leads to the unstable dynamic load shedding performance of the system.