An Application Research Of Equivalent Disturbance Fed Forward Nonlinear System Decoupling Method On AC Speed Regulation

AC speed regulation has been greatly valued, and widely applied, because of itsexcellent speed-regulating performance, big power factor and high energy efficiency. Inthis paper, an AC speed regulation scheme based on Equivalent Disturbance Fed forwardNonlinear System Decoupling (EDFND) method, different from dominant schemes, isdesigned, and the issues of the design in principle as well as the design of low-levelembedded software system are studied.The development of speed regulation technic for AC asynchronous motor is generallyintroduced. The ideas of dominant AC speed regulation schemes are reviewed. EDFNDmethod and its development as well as its application status in AC speed regulation isintroduced.EDFND method builds state equations of plant-replaced model which involvesequivalent disturbance, observes and compensates the disturbance, finally realize thedecoupling control on the nonlinear coupling plant. There’s no accurate mathematicalmodel of plant in EDFND method, and the design process is totally within linear systemtheory.The AC speed regulation scheme based on EDFND method is designed, and therealization diagram of EDFND AC speed regulation based on micro controller F2812isgiven. That scheme only adopts linear control theory to realize the decoupling control ofstator flux and electro-magnetic torque, and needs no reference frame variable, no accuratemathematical model of asynchronous motor. The equivalent disturbance fed forwarddecoupling controller, speed regulator, the method for electro-magnetic torque detectingand the method for detecting rotor speed are designed.An accurate and effective result of flux observer must be acquired to make thedecoupling control in EDFND AC speed regulation can be achieved. For this reason, anovel drift-estimating and corrective feedback algorithm for voltage model of stator flux isgiven. This algorithm provides available signals only with pure integrators and reject theDC or low-frequncy drifts in the stator flux estimated. The inputs and outputs of thevoltage model in different moments are applied to construct an equation set which involvesdrifts, and the drifts can be calculated. Then the drifts are eliminated through feedbackcontrol.The embedded low-level software system of EDFND AC speed regulation is designed,the basic issues of designing low-level software for AC speed regulation analyzed, proper data format adopted, the resource on F2812chip appropriately allocated, effective interruptstructure arranged. The ADC results are correct to maintain the reliability of feedback datasouce. The recursion formulas of observer for equivalent disturbance and speed regulatorare given. The capture and quadrature encoded pulses units on F2812chip are used tocalculate rotor speed.The simulative or experimental results of main designs are given. The simulationverifies that the decoupling control of electro-magnetic torque and stator flux can berealized, the system is stable, and the speed regulation performance is satisfying. Theexperiments indicate that the torque detection algorithm is correct and the drift-estimatingand corrective feedback algorithm for voltage model of stator flux is effective. All theexperimental results prove that the software system of EDFND AC speed regulation isstable and effective.