An Equivalent Drift Feedforward Non-linear Decoupling(EDFND) Control Method Of AC Drive System

AC driving systems has captured great attention and been widely used for its excellent performance, high power factor and high efficiency. This dissertation proposed a novel Equivalent Drift Feedforward Non-linear Decoupling(EDFND) control method for AC driving systems. Two key problems in this method were studied, and the new method was successfully applied in AC variable frequency speed regulation system. The design of EDFND was displayed in detail. The system simulation was performed and experimental research was carried out finally.The linear time-invariant control method of multi-variable nonlinear systems is named as EDFND method. This method achieved decoupling control of multi-variable nonlinear system by equivalent to an alternative model through the establishment of the state observer compensation technology. There are two key problems in the EDFND method--the existence issue and of linear substitute model and the stability issue of the compound system.This paper proved the existence theorem of EDFND controlled AC speed control system by comparing stator flux oriented VC system driven by frequency converter, which provided theory basis for EDFND method of AC speed control system.The AC speed control dynamic decoupled control system based on EDFND method was designed and the stability was analyzed basing on small signal model. The dynamic compensation was designed to ensure the stability.The software was designed. The theory and digitalization of SVPWM in three phase frame was studied. The digital filter of voltage and current were designed. The improvement of drift-estimated and feedback-corrective algorithm for voltage model of stator flux was studied and digitalized.The simulation and experiment were performed. The simulation demonstrated that the existence prove of linear substitute model to dynamic decoupled AC variable frequency speed control system is right. The EDFND control system can realize decouple of torque and flux, which can achieve the equal performance as vector control. The stability design of EDFND control system based on small signal linear model was proved reasonable and effective. Both the simulation and experiment show that the SVPWM algorithm is right,the line voltage and line current filter is effective. The promoted flux detection algorithm gain satisfied result.The EDFND method is independent of accurate mathematical model of AC induction machine, doesn’t need the coordinate transformation, and the controller is completely linear time-invariant, which is convenient for industrial application. The EDFND method provides a brand new thought for AC speed control system, promising great study value and wide application prospect.