Zero-Low Speed Redundancy Control Of Electric Vehicle Under Position Sensor Failure

In view of the excellent advantages of strong environmental adaptability and high efficiency,IPMSM is widely used in electric vehicles in the current mainstream market by many automobile companies.As a popular motor control method,vector control requires position sensor to realize its high performance control purpose.However,due to its harsh working environment,the position sensor will inevitably fail in actual use,become one of the failure sources of motor drive system failure,which will reduce the safety of electric vehicles on the road.The background of this paper is the failure of motor position sensor on electric vehicle,and the sensorless control method is used to replace the position sensor to output the motor rotor position and angular speed information for software redundancy,so that the electric vehicle can continue to drive in the zerolow speed region without the position sensor.At the same time,a control strategy to reduce the negative effects of this method without losing the estimation accuracy is also proposed.On the basis of deducing the simplified mathematical model of high frequency motor voltage signal injection,the sensorless control method based on square wave voltage signal injection is firstly introduced,and its feasibility as software redundancy after the failure of electric vehicle motor position sensor is verified by simulation,and the problem of noise and electromagnetic interference caused by the power spectrum spike at the multiple of the injection frequency in the high frequency current excited by the traditional fixed frequency square wave signal injection method is introduced.Then the sensorless control technology based on random frequency voltage signal injection method is studied.Two voltage signals with different frequencies are randomly selected and injected by the control system.Considering the fact that the algorithm in the digital system cannot be truly randomly selected when implemented,the problem of local power spectral density concentration of high-frequency response current is also obvious.Therefore,this paper uses an adaptive method to change the switching probability.By observing the results of the previous injection signals,the switching probability is automatically changed according to the designed rules,and the power spectral density of the high-frequency response current is further expanded.In addition,the principle of digital control system delay is analyzed,and the current extraction method without filter is proposed to suppress the sampling delay and reduce the use of filter.A rotor position estimation method without demodulation signal is designed to improve the system response speed and reduce the error of rotor position estimation.Finally,high performance sensorless control of permanent magnet motor at zero low speed is realized.Finally,the high performance sensorless control of IPMSM is realized.The correctness and effectiveness of the proposed method are verified by principle analysis and simulation.Finally,the overall design scheme of the motor controller based on the discrete hybrid silicon carbide IGBT power device is proposed.The main circuit design and the selection of key devices are completed.The 2kw controller prototype based on the silicon carbide power device is built with DSP 28379 D as the main control chip.The hardware design of the motor driver is verified by testing.