Study On A New Optimal Control System Of Sensorless Bldcm

The BLDC Motors with the simple,reliable and efficient performance has been applied in each field broadly.For the shortcoming of position sensor used in drive system,the sensorless controlling strategy becomes one of the most important direction.Based on this situation,this paper starts from the working principle and the mathematic model of BLDC Motor,and focuses on the position sensorless optimal control strategy.Finally,it also designs a hardware test platform to verificate the strategy.Back-EMF algorithm is widely used position detecting algorithm at now.Therefore,this paper dicusses the advantage and the disadvantage of back-EMF algorithm in detail,proposes a new method of detecting position signal and phase compensation,in order to solve the problem of narrow speed scope as well as lagging position information.In this method,by using the CORDIC and FIPS theory in the field of digital signal processing,the rich hardware logic resources in FPGA are utilizd to implement the detecting position error compensation at the arrange of fulll speed,improve the detecting accuracy and the measurement range of the position signal.Secondly,this paper also discusses the working process of the “3-state startup method” detaily.By analyzing the accelerating operation,a controling program which is based on the principle of recursivly calculating comutation time sequence has been proposed.Meanwhile,to reduce the stator resistance voltage drop and load disturbances,the program is still combined with the close-loop feedback strategy,achieve the function of improving the torque control effect of the starting process.In the end,by using the hardware modulation designing method,this paper accomplishes the work of compiling of the drive system's software programs at the plan of the Altera Corporation Cyclone II series FPGA chip.The programs mainly include A/D interface module,average-median filter module,open-loop start-up module,back-EMF detection module,interactive interface module,PLL speed regulation module,PI current regulation module,PWM modulation and so on.Experimental results show that the proposed sensorless BLDCM controling strategy has a very good static and dymatic characteristics,could realize the aim of high reliability and accuracy,which are very useful in the special application.