Study On Motor Control Methods Under Large Dynamic Current

When Opto-electronic Tracking system keeps tracking on the maneuvering target,the high tracking accuracy and tracking speed is necessary. When Opto-electronic Tracking system works on low elevation tracking, the frame motor operates smoothly and motor current changes in a small range. This affects a little on the tracking accuracy and leads to a more accurate tracking effect. However, when Opto-electronic Tracking system moves fast in high elevation situation, the frame motor current changes sharply. On one hand, the limitation of motor current loop bandwidth results a dropping in speed loop and position loop tracking speed. On the other hand, the limitation of current detection method causes a decreasing in current measurement accuracy. This eventually leads to the tracking accuracy falling in Opto-electronic Tracking systems.Thus this article starts to research in this two aspects descriped above. And proposes modulation wave increasement estimate PWM update immediatly algorithms to expand the current loop bandwidth. This paper finds that the current sampled at the beginning and midpoint of the carrier period is equivalent to the fundamental current values, so as to reduce the twice carrier frequency harmonics.And applies the centralized Kalman filter fusion in current sensor data fusing to obtain a high measurement accuracy.This paper deduces Permanent Magnet Synchronous Motor(PMSM) control theory and Space Vector Pulse Width Modulation(SVPWM) algorithm. And discusses the principles of id = 0 control theory. Then combines id= 0 control theory with SVPWM algorithm.Besides this paper gives the SVPWM wave generation step to make theoretical guidance for the experimental verification of permanent magnet synchronous motor control.This paper deduces the current loop transfer function also. And analyzes the impact of feedback delay and forward delay on current loop bandwidth.Under the analysis and comparison of several PWM update methods, this paper proposes modulation wave increasement estimate PWM update immediatly algorithms. This method decreases the current loop forward delay, and expands the motor current loop bandwidth 3 times as that in traditional SSSU(single sample single update) method. As a result, the tracking accuracy and speed of position loopand speed loop has been improved.Then this paper finds that the current sampled at the beginning and midpoint of the carrier period is equivalent to the fundamental current values in synchronous sampling. This reduces the current harmonics at the twice carrier frequency and higher harmonics significantly.This paper applies multisensor in the motor current sampling. And also, this paper applies centralized Kalman filter fusion in the current sensor data fusion of different ranges and precisions. This algorithm can process data in real-time in the principle of minimum mean square error and achieve a high accuracy in lager range.The algorithm has been verified by experiment.Finally, the improved algorithm is been achieved in DSP/FPGA experimental platform. Then the amplitude-frequency and phase-frequency response is been measured. It is proved that the improved current loop bandwidth expansion theory is correct and feasible.