Research On Hybrid Identification Method For Rotor Position Of Permanent Magnet Synchronous Motor

Permanent Magnet Synchronous Motor(PMSM)has been widely used in the field of industrial application because of its advantages of large power density,high efficiency and wide operating range of constant power.In order to realize high performance flux orientation control of PMSM,accurate rotor position need to be obtained in real time.Usually,the rotor position is obtained by encoder.However,the installation of encoder will bring many problems,such as increasing the cost of the system,increasing the axial length of the motor and reducing the robustness of the system.Aiming at the interior permanent magnet synchronous motor,this paper studies the rotor position identification algorithm in wide speed range by theoretical analysis,simulation verification and experimental verification,and the specific contents are as follows:Firstly,in order to realize the smooth start of permanent magnet synchronous motor,a robust and easy to engineering implementation of the rotor initial position identification method is studied.This method only needs to inject a certain amplitude and different phase angle pulse voltage vector to the stator windings,and then detecting the amplitude of the current response.The initial position of the rotor can be identified according to the corresponding amplitude of the current.Then,aiming at the disadvantage of introducing band-pass filter and Low-pass filter in the traditional low speed position identification algorithm,a new low speed rotor position identification algorithm is studied.The algorithm can obtain the rotor position error directly according to the current difference caused by the injected voltage,and then obtain ing the rotor position and velocity through a software phase-locked loop.This method avoids the use of filter when the rotor position is identified.The algorithm is simple,the anti-interference performance is strong,and the system dynamic response is fast.The correctness and validity of this position identification algorithm are verified by MATLAB simulation.Secondly,a sliding mode observer method for the interior permanent magnet synchronous motor is studied for the rotor position identification in the middle and high speed range.Firstly,the extended back electromotive force model of the interior permanent magnet synchronous motor is deduced,and the stator current sliding mode observer is designed based on the extended back electric model,which is used to identify the rotor position.The stability of the sliding mode observer is proved though the second method of Lyapunov stability.The correctness and validity of the sliding mode observer method based on the extended back electromotive force model is validated by MATLAB simulation.Then,in order to achieve smooth switching between the low speed algorithm and the high speed algorithm,a switching strategy based on position error information fusion is studied.In the transition phase,the position error signals of the two methods are combined effectively with the weighted function of velocity correlation,and then th e location and velocity of the rotor in the transition phase can be obtained by using the phase-locked loop.At the same time,a slope function whoes amplitude associated with velocity is designed for the transition of the injected voltage.Finally,the hybrid identification algorithm of rotor position based on DSP is validated experimentally.The experimental results verify the correctness and validity of the hybrid position identification method studied in this paper.