The Research On Asymmetrical Running Of Multi-phase Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor (PMSM) has been used widely toapplications need high power density and better performance for control,due to thefact that it has small volume, light weight, fast response, high power factor and thesimple control method. Multi-phase permanent magnet synchronous motor’sreliability is an incomparable advantage over traditional three-phase motor.Thereforemultiphase permanent magnet synchronous motor has get more and more attention inthe aviation aerospace,marine propulsion,and other fields. The high reliability ofmultiphase permanent magnet synchronous motor results from its phase redundancyof phases, which means that when stator winding fell down in open-circuit condition,multiphase permanent magnet synchronous motor can run continuously throughcontrolling the phase and amplitude of remaining normal current. The ability ofsustainable operation in applications that not allowing breaking down is especiallyimportant, therefore the study of multiphase motor running asymmetryly has profoundsignificance.At first, this article introduced the development and history of multiphasepermanent magnet synchronous motor and the current research situation, then, pointedout that the multi-phase motor does not get better performance with more phases,finally this article chose five phase permanent magnet synchronous motor as theresearch object. Firstly,its mathematical model is established in five phase stationarycoordinate system. In order to realize the simple control of the five phase permanentmagnet synchronous motor,mathematical model in two-phase rotary stationarycoordinates is established also. Introduced the field oriented control technology basedon id=0, then the effectiveness of the proposed control method is confirmed bysimulation results.When five phase permanent magnet synchronous stator winding occurredopen-circuit fault in a phase or two phases, the change synthesis of stator magneticpotential degrade control performance greatly, and this is verified by simulation also.Two compensation control method was presented in this paper.the one bases on thestrategy to make stator magnetic potential stay same. The other method bases onmirror symmetric method and single phase five open phase permanent magnetsynchronous motor optimization compensation current control method. The former is in a constraint condition keepping each phase current amplitude equal.The currentphase and amplitude are adjusted to compensate for the magnetic potential lossesfrom the open phase. Method two,no longer keepping each phase current amplitudeequal, only fault current of axisymmetric amplitude is equal,with lower copper lossdue to the decrease in the total current amplitude.Simulation has been done to verifythe effectiveness of the method one and superiority of method two.The design of five phase permanent magnet synchronous motor drive systemincluding a hardware circuit design and software flow chart of the system is providedat the end of the paper.