Dual-redundancy Permanent Magnet Synchronous Motor Research Articles

A Novel Dual-Redundancy Permanent Magnet Synchronous Motor With Small Teeth

A novel dual-redundancy permanent magnet synchronous motor (DRPMSM) with small teeth is proposed, which combines the advantages of fault-tolerant permanent magnet synchronous motor (PMSM) and multi-phase PMSM. When fractional slot concentrated winding (FSCW) is used in PMSM, no electromagnetic coupling can be realized by selecting a reasonable slot-pole (SP) combination and using single-layer (SL) winding. However, the goal of no electromagnetic coupling can also be achieved by adding small teeth in the common slot center between two adjacent phase windings under appropriate SP combination and double layer (DL) winding. Compared with the former method, the latter has smaller eddy current loss and a lower saturation level of the magnetic field caused by lower-order harmonics. In addition, the influence of small teeth on electromagnetic properties is analyzed. The correctness of the theoretical derivation is verified by simulation and experiment.

Online Diagnosis of Inter-turn Short Circuit for Dual-Redundancy Permanent Magnet Synchronous Motor Based on Reactive Power Difference

The Dual-Redundancy Permanent Magnet Synchronous Motor (DRPMSM) with weak thermal coupling and no electromagnetic coupling among phase windings has two sets of three-phase symmetrical windings. Under normal conditions, two sets of windings can operate simultaneously, and once one set has an inter-turn short circuit fault (ISCF), the other set will operate alone, so a DRPMSM can be applied in fields with high reliability requirements. According to the equivalent circuit principle, a simplified model of a DRPMSM when ISCF occurs is established in this paper, and mathematical equations for the equivalent resistance, inductance and induction electromotive force (EMF) are derived. Based on the simplified circuit principle and instantaneous power theory, combined with the analysis of the fundamental wave in the two sets, an online diagnosis method of the ISCF for DRPMSM is proposed based on the reactive power difference and the feasibility of the method is verified by experiments.

Influence of Small Teeth on Vibration for Dual-Redundancy Permanent Magnet Synchronous Motor

The dual-redundancy permanent magnet synchronous motor (DRPMSM) has high reliability in its applications. Compared with the traditional permanent magnet synchronous motor (PMSM), small teeth were added to the stator in DRPMSM and its vibration has new characteristics. This paper derived the analytic expression of the radial electromagnetic force for PMSM in the air gap based on the Maxwell stress equation and summarized its sources. The simplified stator teeth model of the traditional PMSM and DRPMSM were established in 12-slot/10-pole (12s10p), and the analytical expression and Fourier expansion of radial electromagnetic force on the teeth were given. The electromagnetic and structural finite element models of the motor were established, and analyses of modal and harmonic response were carried out. The simulation results show that the stator vibration amplitude of DRPMSM is smaller than that of traditional PMSM at no-load and is also bigger under rated load. Furthermore, in order to guarantee the low amplitude of stator vibration under rated load for DRPMSM, the width of the small teeth should be smaller.

On-Line Detection of Coil Inter-Turn Short Circuit Faults in Dual-Redundancy Permanent Magnet Synchronous Motors

In the aerospace and military fields, with high reliability requirements, the dual-redundancy permanent magnet synchronous motor (DRPMSM) with weak thermal coupling and no electromagnetic coupling is needed. A common fault in the DRPMSM is the inter-turn short circuit fault (ISCF). However, research on how to diagnose ISCF and the set of faulty windings in the DRPMSM is lacking. In this paper, the structure of the DRPMSM is analyzed and mathematical models of the motor under normal and faulty conditions are established. Then an on-line ISCF detection scheme, which depends on the running modes of the DRPMSM and the average values for the difference of the d-axis voltages between two sets of windings in the latest 20 sampling periods, is proposed. The main contributions of this paper are to analyze the calculation for the inductance of each part of the stator windings and propose the on-line diagnosis method of the ISCF under various operating conditions. The simulation and experimental results show that the proposed method can quickly and effectively diagnose ISCF and determine the set of faulty windings of the DRPMSM.

Minimization of the Electromagnetic Torque Ripple Caused by the Coils Inter-Turn Short Circuit Fault in Dual-Redundancy Permanent Magnet Synchronous Motors

With the development of electric vehicles and More-Electric/All-Electric aircraft, high reliability is required in motor servo systems. The redundancy technique is one of the most effective methods to improve the reliability of motor servo systems. In this paper, the structure of dual-redundancy permanent magnet synchronous motor (DRPMSM) with weak thermal coupling and no electromagnetic coupling is analyzed and the mathematical model of this motor is established. However, there is little research on how to suppress the torque ripple caused by short-circuited coils in the DRPMSM. The main contribution of this paper is to present the advantages of DRPMSM and to find a way to suppress the torque ripple caused by the short circuit fault in DRPMSM. In order to improve operation quality and enhance the reliability of DRPMSM after a short circuit occurs, the torque ripple caused by the coils inter-turn short circuit fault in DRPMSM is analyzed in detail. Then, a control method for suppressing the electromagnetic torque ripple of a short-circuited coil is proposed for the first time by using an improved adaptive proportional resonant (PR) controller and a proportional integral (PI) controller in parallel. PR control is a method of controlling alternating components without steady-state error, and it can be used to suppress torque ripple. DRPMSM adopts speed and current double closed-loop control strategies. An improved adaptive PR controller and a PI controller are employed in parallel for the speed loop, while traditional PI control is adopted in current loop. From the simulation and experimental results, the torque ripple is reduced from 45.4 to 5.6% when the torque ripple suppression strategy proposed in this paper is adopted, in the case that the speed is 600 r/min. The torque ripple suppression strategy based on the PR controller can quickly and effectively suppress the torque ripple caused by the short-circuited coils, which makes the motor speed more stable.