Research On Phase Current Reconstruction Algorithm Of Permanent Magnet Synchronous Motor Based On Single Current Sensor

Permanent magnet synchronous motor(PMSM)has been widely used in the fields of industrial servo and aerospace due to its high power density,high reliability and high precision.Modern permanent magnet synchronous motors mostly adopt closed-loop vector control drive system,which requires real-time detection of phase winding current and rotor position information.However,both position sensors and current sensors are expensive,which adversely affects the cost of the drive system.Therefore,it is important to reduce the number of sensors without reducing the performance of the control system.More than existing phase current reconstruction techniques using a current sensor installed on the dc bus to realize the three phase current detection,but its low modulation region and sector boundary area exists blind area need complex compensation algorithm,to solve these problems,this paper studies a kind of zero vector sampling phase current reconstruction technique,and the implementation principle,the error analysis of the current to refactor blind area,and different sampling modes including robot structure is studied.Firstly,the mathematical model of permanent magnet synchronous motor control system is established on the basis of coordinate change,and several control strategies of motor vector control are introduced.This paper makes a comparative analysis of the sinusoidal control scheme of permanent magnet synchronous motor,and concludes that the SVPWM modulation system is 15% higher than SPWM,which makes the dc bus voltage utilization rate of SVPWM higher.Secondly,the basic principle of phase current reconstruction technology is studied,and the corresponding relationship between the branch current of the three-phase voltage source inverter and the phase current of the winding under different voltage vectors is obtained.Based on the basic principle of the phase current reconstruction technique of the dc busbar sampling,the pulse shift method and the vector insertion compensation algorithm in the blind area of the current reconstruction are introduced briefly,and it is proved that the pulse shift method does not affect the actual output voltage vector.Then,the current sampling method of zero vector period is introduced,its working principle is expounded,and its effective working area and specific application range are obtained by theoretical calculation,which solves the problem that the effective voltage vector amplitude of dc busbar sampling method is too small to reconstruct the three-phase phase current in the low modulation area.However,there is a delay of half PWM period in the two samples,which will introduce some current reconstruction errors.When the motor runs smoothly.When the current changes little,the reconstruction error will not have any impact on the performance of the system,and then when the current waveform of the motor changes violently or the motor speed is too high,the sampling delay of half PWM period may cause a large error.Finally,the current sensor installation location is improved,this paper proposes a hybrid time current sampling method,make its can not only in the zero vector to complete the reconstruction of the current period of current detection,also can in the effective period of the voltage vector phase current collected enough information,and analyzes the effective working area and scope of use.Then the reconstruction error principle caused by phase current mutation is analyzed,and the error caused by phase current mutation is effectively reduced by improving the phase current reconstruction times in PWM cycle with the mixed sampling method.The phase current reconstruction technique of permanent magnet synchronous motor under different voltage vectors is studied in this paper.The phase current reconstruction under the dc busbar sampling method and the zero vector sampling method are compared and analyzed,and the phase current reconstruction under the effective voltage vector time and the phase current reconstruction under the zero vector time are fused by improving the installation position of the sensor.On the premise of ensuring the control performance,this reconstruction algorithm is of great significance to the application of low cost PMSM drive system.