Research On Permanent Magnet Synchronous Motor Flux Weakening Control System

Permanent Magnet Synchronous Motor (PMSM) is characterized by small volume, large power density, low loss and high efficiency. It has been widely applied in high-precision and high-speed field, like CNC machine and industrial robot. The back electrical motive force of the machine will increase when increase happens in motor speed of the motor. But stator voltage can’t increase unlimitedly and booster speed control range is restricted. However, if the permanent magnet synchronous motor speed range needs to be broadened, it has to reduce the size of the magnetic chain by flux-weakening control. Due to permanent magnet synchronous motor is excited through permanent magnet. It cannot directly reduce the power of magnetic field by changing the field current. The alternative way is to adjust the quadrature axis and direct axis current via reversing direct axis current increase motor, so that the synthetic gas gap field was weaker. Therefore, voltage relationship can keep balanced and the goal of speeding up by weakening magnetic can be achieved. Based on flux-weakening control, this paper will focus on speeding up by weakening magnetic and make some relative researches.Firstly, it would introduce the principles and basic structures of permanent magnet synchronous motor, make contractive analysis among the mathematical model in static three-phase coordinate two phase static frame and rotary two-phase coordinate. Then, it can pay more attention on determining space voltage vector modulation technology.Secondly based on the d and q axis voltages steady state equation of surface-mounted permanent magnet synchronous motor, discussed the operation range of PMSM using the gradient method, and gives the d and q axis calculation of correcting current in various operational regions. Aiming at the shortage of complex gradient calibration algorithm. It will make strategy of flux-weakening control, which based on maximizing the torque-current ratio. Meanwhile, while efficiently broadening the speed range, it also needs to make the motor in high load capacity in order to satisfy the requirement of high speed in machining. Besides, applying the simulation software MATLAB/Simulink into analyzing the flux-weakening control method which based on maximizing the torque-current ratio, the result shows that the method has efficiently broadened the range of speeding the motor, and has good performance of quick current response.At last, the flux-weakening control system is consist of a control panel that cored on TI’s TMS320F28335 chip, a power-driven core experimental hardware platform based on Fuji’s Intelligent’ Power Module (IPM 6MBP30RH060) and relevant software system. After system debugging and experimental analysis, the result proves the accuracy of weakening control system which mentioned in this content. Furthermore, it lays a foundation to improve the Permanent Magnet Synchronous Motors (PMSM) weakening Control System.