Online Diagnosis Of The Coils Inter-turn Short Circuit Fault Of The Dual-redundancy Permanent Magnet Synchronous Motor

This paper is one part of“dual-redundancy permanent magnet synchronous motor（DRPMSM）with low thermal coupling and non-electromagnetic coupling between windings of phases”,which is supported by National Natural Science Foundation of China.It mainly studies the main features of dual-redundancy permanent magnet synchronous motor,the influence of short circuit between turns of coils on motor operation and an on-line diagnosis method of coil inter-turn short circuit.The main tasks were shown as follows:Firstly,the dual redundancy permanent magnet synchronous motor with low heat coupling and non-electromagnetic coupling between phase windings is analyzed.The mechanism of no mutual inductance of this kind of motor is explained,and it is validated by finite element analysis.The dissertation derives the expression of inductor and the equivalent three-phase circuit of the motor is obtained by using the characteristic of no mutual inductance between the phase windings.Then based on the circuit theory,the paper proposes the equivalent circuit model of the phase winding for inter-turn short circuit fault of coils.The circuit is further simplified and a simplified circuit with only equivalent resistance,equivalent inductance and equivalent inductive EMF is obtained.The analytical expressions of the parameters in the simplified circuit are derived without considering the current harmonic and negative sequence current components.The adjustment of the current regulator is very fast,the current of the normal winding and the fault winding is almost the same when the inter-turn short circuit occurs.So many fault diagnosis methods based on current are not suitable for dual-redundancy permanent magnet synchronous motor with this structure.The active and reactive power of normal phase and fault phase are calculated from the point of view of circuit theory and instantaneous power theory,and the results are consistent.The difference between instantaneous active power and instantaneous reactive power of normal winding and fault winding is deduced in detail.The feature of this difference is derived according to the phasor diagram of the motor in different operating states.Based on the state of the motor and the average value of the difference of instantaneous power（active power or reactive power）,an on-line fault diagnosis method for inter-turn short circuit of windings is proposed.A fault diagnosis module when coils occur inter-turn short circuit fault is built in MATLAB/Simulink.The double redundant motor control is a double closed loop system of rotational speed and current using the control strategy of_di^（9）（28）0.After the windings occuring the inter-turn short circuit faults,the phase current,as well as the difference of the contribution of the normal winding and the fault winding to the electromagnetic torque can be observed by simulation.The effects of short circuit turns,rotation speed,short circuit contact resistance and load on the fault characteristic quantity are studied through qualitative analysis and simulation.Finally,the hardware system was designed by using Digital Signal Processing（DSP）TMS320F2812 as the main control chip.It is proved that the online-diagnosis method of the coils inter-turn short circuit fault of the DRPMSM proposed in this paper is feasible.