Sensor-less Vector Control System Study Of Permanent Magnet Synchronous Motor In Electric Vehicle

At present, due to environmental pollution and energy crisis, electric vehicle has gradually become the preferred means of transport. Since permanent magnet synchronous motor (PMSM) with several advantages, such as high efficiency, simple structure and high power density, it has gradually become hot research in the field of electric vehicle driving. In the motor drive system, the rotor shaft usually install encoders or rotary transformers in order to get the information of the rotor speed and position. However, installation of mechanical sensors not only increase system cost, but also may reduce the reliability of the system. So the study on the PMSM sonsorless control has very significant meaning in the high-performance control and some special occasion. At present, the sensorless control methods of PMSM can be divided into two main types, one is based on the fundamental equation of the motor, and it is applied to medium or high speed motor rotor position detection for it is sensitive to the motor parameters; and the other is for low speed ones, that high-frequency signal injection method. The paper focuses on the rotor position detection of the PMSM at low speed.In this paper, we take the interior-PMSM into account. At the beginning the paper introduce the mathematical model, then analyze and simulate the vector control of PMSM based on SVPWM, at last paper focus on the method of injected high frequency signal for detecting the rotor position information. Through injecting high-frequency voltage signal to the two-phase stationary coordinate system, using salient effect of the motor, then the rotor position information can be derived from the current response. The key technologies for extracting rotor position are also described, such as delay circuit, synchronous frame filter (SFF), and phase locked loop (PLL) based on heterodyne method, then make compensation for the rotor poles. The simulation result of dynamic and static performance of the system based on MATLAB/SIMULINK shows that this method can achieve the detection of rotor position. The article also discusses the impact of non-linear of the inverter, especially the dead-time, and some compensate measures are suggested. The simulation can be seen by the dead-time compensation, the current waveform distortion significantly changed for the better. At last, the whole sensorless control system of PMSM is designed based on DSP.