Research On Position Sensorless Control Of Vehicle PMSHM Based On Dead Zone Compensation

With the popularization of the Internet of Things and intelligence in the automotive industry,in-wheel motor-driven electric vehicles have become more and more popular among the general public due to their advantages in intelligence and low pollution.Permanent magnet synchronous motors have become the mainstream choice of current vehicle drive hub motors due to their simple structure,high power density and high efficiency.Vehicle drive hub motors have higher requirements for their own dynamic performance,and their overall control performance has a greater impact on the power and safety of electric vehicles,so how to accurately obtain the rotor position of the hub motor is very important.Due to the complex and changeable driving conditions of in-wheel motors driving electric vehicles,mechanical sensors generally used to obtain rotor position information are prone to failures,which will affect the driving safety and dynamics of electric vehicles.Therefore,the position sensorless control technology of vehicle drive motors has been a research hotspot in recent years.The main contents of this paper are as follows:First of all,in order to realize the vector control of permanent magnet synchronous hub motor(PMSHM)for vehicles,a surface mount PMSM mathematical model was established in two different coordinate systems,and the principle of PMSM vector control was briefly introduced.Selected a suitable control strategy,and analyzed the basic principles and algorithm implementation of Space Voltage Vector Pulse Width Modulation(SVPWM)technology.On this basis,in view of the influence of the inverter dead zone effect on the control performance of the in-wheel motor,an in-depth analysis and comparison of the traditional dead zone compensation scheme is carried out,and a new dead zone compensation method is proposed to offset the dead zone effect.Impact.Finally,a vehicle PMSHM vector control simulation model based on dead zone compensation is built,and the simulation results further verify the efficiency of the method.Secondly,based on the saliency of the vehicle PMSHM and the requirements for start-up smoothness,the pulse high frequency voltage injection(PHFVI)algorithm is used to estimate the position of the vehicle PMSHM rotor at low speed.On the basis of the established mathematical model of PMSHM under high frequency excitation signal,the principle of PHFVI algorithm is analyzed and deduced,and a current signal extraction method is proposed and a position tracking observer is designed to carry out signal processing on the signal containing rotor position information.Extract and estimate.Finally,the proposed dead zone compensation method is added to build a vehicle PMSHM low-speed sensorless control simulation model based on the new dead zone compensation,and the feasibility of the proposed estimation algorithm is verified through the simulation results,and the dead zone effect is further verified In the low-speed stage,it has a greater impact on the motor control performance.Then,due to the fact that the rotor position estimation algorithm at low speed has large errors and poor dynamic performance at the medium and high speed stages,the extended Kalman filtering(EKF)method based on the back EMF of the motor is used to realize the low-speed PMSHM for vehicles.Estimation of rotor position.For the Kalman filter method,the discrete Kalman filter principle and the discretization of the continuous equation are analyzed in detail,and the extended Kalman filter algorithm is further proposed.The basic principle and calculation process of the EKF algorithm are analyzed and deduced in detail,and established The position sensorless control system model of PMSHM for vehicles based on EKF algorithm is presented.Finally,the proposed deadzone compensation method is added to build a vehicle PMSHM mid-and high-speed sensorless control simulation model based on the new dead-zone compensation,and the simulation results verify that the proposed estimation algorithm has high rotor position estimation accuracy,and It is further verified that the dead zone effect has little influence on the motor control performance in the middle and high speed stages.Finally,in order to realize the sensorless control of the vehicle PMSHM in the full speed range,so that the vehicle PMSHM can smoothly switch from the low-speed to the medium-high-speed transition section,a weighted switching method is designed.And built a simulation model of PMSHM full speed range sensorless control for vehicles after adding a new dead zone compensation algorithm.The simulation results show that the method has better torque response capability.