Research On The Feedforward Control Of EPS PMSM Using Parameter Identification

Current following control is one of the key strategies of EPS equipped with permanentmagnet synchronous motor (PMSM), the difficulty lies in the requirements of improving theresponse rate, meanwhile, minimize high-frequency fluctuation moment with a goodstability. Many documents said that adding feedforward loop on the basis of feedback loopcan improve the control effect. Since the motor parameters can change with the operatingcondition, in order to improve the accuracy of the feedforward loop, it is necessary to carryout online identification over motor parameters. This thesis is focused on using the methodsto improve the current following control of EPS PMSM.One of the difficulties for online identification over motor parameters is owed to rankissues. After research, it was found that the proportion of the induced electromotive force inthe feedforward loop is small, so the stator inductance value was set as a constant in thefollowing research.In this thesis, an on-line model reference adaptive observer for the stator resistance androtor flux identification was designed using Popov super stability theory. Under the controlstrategy ofi d=0, since the constraints from the d-axis voltage equation is weak, thesituation appears that identifying two independent parameters with a q-axis voltage equation,which causes that the identification result is not converged. Taking into account of thecharacteristics of the application and of the fact that the motor parameter changes withtemperature which changes slowly, a parameter identification strategy was designed withthe feature of "long identifying interval and increased during the identification process".The feasibility of the scheme was validated by the results from simulations andexperiments.To compare the effect of different control schemes, simulations and experiments atdifferent environment temperature were conducted, in which "PI control","feedforward-PI control" and "feedforward with parameters identification-PI control" were usedrespectively. From the results, it was concluded that high precision feedforward loop canimprove the PMSM current following control greatly in EPS application.In order to improve the efficiency of embedded code generation, automatic codegeneration technology was also used in this thesis.Research in this thesis was carried out on the EPS motor test-rig. In order to validatethe conclusion further, it is necessary to conduct more tests on EPS system test device in thefuture.