Position Sensorless Control Of Permanent Magnet Synchronous Motor Based On Single Current Sensor

In the field of motor control,it is an important research and practice problem to realize the control algorithm more reliably with lower hardware costs and smaller volumes.For permanent magnet synchronous motor(PMSM),using a single current sensor to reconstruct the three-phase current and then using position sensorless control can greatly reduce the cost,volume,and complexity of control hardware and increase the reliability.However,the current reconstruction scheme has the problems of reconstruction dead zone and current reconstruction error,which reduces the sensorless control performance of the motor.Therefore,it will make a big difference to broaden the applications of the single current sensor control system through in-depth research on sensorless control technology of PMSM using a single current sensor and reducing the influence of the two core problems in the current reconstruction scheme to improve the performance.In the current reconstruction scheme using a single current sensor to sample the DC bus current of the inverter,the current should be sampled during the active basic voltage vector.When the action time of the active voltage vector is not enough to sample current stably,the phase current information is missing.This resulted in the reconstruction dead zone problem.There is a time interval between the sampling time of the single current sensor and the sampling time of the three-phase current sensor,and there is also a time interval between the two sampling times of the single current sensor in a switching period.These two types of time intervals lead to errors in the reconstructed current.To solve these two problems,an improved current sampling and reconstruction(ICSR)scheme is proposed.By shifting the switching state of the inverter,the time interval between the two sampling times is fixed as the minimum sampling window time.Thus the reconstructed dead zone is transferred to the low modulation area,and the current reconstruction error is reduced.When the PMSM runs in the low-speed range,the rotor position information can be extracted from the high frequency(HF)current by injecting the HF voltage signal.The output voltage amplitude can be increased,which is separated from the reconstruction dead zone in the ICSR scheme.However,the current reconstruction error in the ICSR scheme affects the extraction of HF current,which reduces the accuracy of the estimated rotor position.To solve this problem,a current compensation scheme with compensation coefficients is proposed.The compensation coefficient is estimated and corrected by the HF current,thus the current compensation scheme can be adjusted online.Moreover,the ICSR scheme simplifies the current compensation algorithm,which makes the current compensation step only need one step and reduces the calculation amount.The accuracy of the reconstructed HF current increases after compensation,which reduces the error of the estimated rotor position and broadens the injection frequency range of HF voltage.In the high-speed range,the linear extended state observer(LESO)is used to observe the equivalent back electromotive force(EMF),and then the rotor position is estimated.Aiming at the problem of current reconstruction error in single current sensor control,which affects the performance of motor control,the current compensation method based on LESO is proposed based on the ICSR scheme.The improved LESO is used to observe the equivalent back EMF and the current change rate under any voltage excitation.The reconstruction error is calculated to compensate for the reconstructed current by using the output voltage of the inverter and the current change rate during the interval of two types of sampling time.The proposed current compensation scheme reduces the current error in the ICSR scheme and improves the performance of the single current sensor control scheme.The weighted coefficient method is used to switch between the above two current compensation and rotor position observation schemes.The estimated rotor position in different speed ranges can be smoothly transited.And the control of PMSM in the full speed range using a single current sensor is realized.To verify the effectiveness and feasibility of the proposed single current sensor control scheme,the simulation and experimental platform of the PMSM control system using a single current sensor is built.The control performance test and comparison of various working conditions are set.The simulation and experimental results show that the proposed single current sensor control scheme can effectively reduce the reconstruction current error and improve the control performance of the PMSM while realizing the current reconstruction and rotor position estimation.