In this paper, a new power switch open-circuit fault diagnosis approach is proposed for the six-phase fault-tolerant permanent magnet synchronous motor (FTPMSM) system based on average current Park's vector (ACPV), which can detect the fault power switch for the FTPMSM system in both normal and phase open-circuit / short-circuit fault-tolerant operation conditions. To detect the power switch open-circuit fault, the moduli of the ACPV based fault detection approach is first proposed for the six-phase FTPMSM system even in phase open-circuit and short-circuit fault-tolerant operation. Then the ACPV based fault location approach is proposed, which can identify the fault power switch according to the sign symbol of the ACPV. The resulting fault diagnosis approach has simple structure and low computation burden, which can detect the power switch open-circuit fault online for the FTPMSM system in both normal and fault-tolerant operation conditions. Finally, the effectiveness of the proposed fault diagnosis approach is demonstrated by a six-phase FTPMSM system experimental platform.

We consider the control design problem for a class of constrained uncertain systems in this paper. The uncertainty in the system, including unknown system parameters and external disturbance, is nonlinear and time-varying. The bound of the uncertainty is described via a fuzzy set. The states of the system are constrained to be bounded. We propose a one-to-one state transformation to convert the bounded state constrained system into the unconstrained system. A new robust control scheme is then proposed for the transformed system, which is in deterministic form and not fuzzy if-then rule-based. By fuzzy description of the uncertainty bound, the optimal design of the control gain is proposed, which minimizes a fuzzy performance index associated with both the fuzzy system performance and the control effort. The analytic solution to the optimization problem is demonstrated to always exist and be unique. The resulting control can guarantee uniform boundedness and uniform ultimate boundedness of the uncertain system, while minimizing the fuzzy-based performance index. In addition, the state constraint can be always guaranteed.

To improve the current tracking performance, this article proposes a new fault-tolerant current control for the six-phase fault-tolerant permanent magnet synchronous motor (FTPMSM) system with multifrequency quasi-proportional-resonant (QPR) control and back electromotive force (EMF) feedforward compensation, which can track the time-varying sinusoidal and nonsinusoidal reference currents in the stationary reference frame (SRF) under normal and fault conditions. First, the multifrequency QPR current controller with shunt topology is proposed to track the time-varying reference current in SRF, which can guarantee the current control performance regardless of the motor speed variation and the load torque change. Second, the optimized feedforward compensation method for the back EMF is proposed to further reduce the steady-state current tracking error, which takes the time delay of the digital implementation into consideration. Finally, the effectiveness of the proposed approach is verified on a 3 kW six-phase FTPMSM platform. The resulting six-phase FTPMSM system with the proposed current control has great current tracking performance, strong robustness to various external/internal disturbance, as well as low computational burden, which can guarantee the multiphase FTPMSM system performance in normal and fault conditions.

To enhance the reliability of fault tolerant permanent magnet synchronous motor (FTPMSM) drives, a new sensorless fault tolerant control with variable phase delay compensation is proposed to guarantee the high-speed sensorless control performance both in normal and fault conditions, which consists of robust observer, non-orthogonal phase locked loop (PLL) and phase delay compensation. To address the high frequency chattering issue, the robust observer is proposed to achieve two health phase back-EMFs estimation, which has good robustness to the parameter variation, external disturbance and the phase fault. Since the non-fault phases used for rotor position estimation are usually not orthogonal, a non-orthogonal PLL is proposed to extract the rotor position information from the observed two phase back-EMFs. To enhance the estimation accuracy as the speed changes, a variable cut-off frequency low pass filter (LPF) is proposed to filter out the high frequency noises in the observed phase back-EMF. Furthermore, the variable phase delay compensation is presented to compensate for the estimation deviation of the rotor position. The resulting sensorless fault tolerant control can guarantee the speed control performance and rotor position estimation both in normal and fault conditions, which is also demonstrated by a six-phase FTPMSM system experimental platform.

This paper proposes a robust observer and non-orthogonal phase locked loop (PLL) based sensorless control for fault tolerant permanent magnet synchronous motor (FTPMSM) in medium- and high-speed range to improve the position detection reliability of the system, which can be applied for the FTPMSM system in both normal and fault conditions. Due to the unsymmetric state of the FTPMSM under fault condition, a new sensorless control scheme based on the back electromotive force (EMF) of non-fault two phase windings is proposed, in which the reference frame transformation is not necessary. The robust observer is proposed to accurately estimate the back-EMF of the non-fault two phase windings, which can guarantee the uniform boundedness and uniform ultimate boundedness of the system regardless of various uncertainties, including external disturbance, parameter variation, and the phase winding fault. The non-orthogonal PLL is proposed to calculate the rotor position and speed of the FTPMSM by using the estimated two-phase back-EMFs. Simulation and experimental results show that the FTPMSM system with the proposed sensorless control has excellent speed control performance, accurate rotor position/speed estimation and great system robustness to various uncertainties, which is able to guarantee the system performance both in normal condition and in fault condition.

This article proposes a novel dual-three-phase high-power high-speed permanent magnet assisted synchronous reluctance starter generator (PMaSynR SG) for aviation application, which has the characteristics of high efficiency, high power density, high reliability, and excellent antishort-circuit ability. The proposed PMaSynR SG can obtain higher efficiency and power density by embedding permanent magnet in the rotor topology compared with the synchronous reluctance generator, and has better antishort-circuit ability compared with the permanent magnet synchronous starter-generator. Moreover, design of dual-three-phase winding is adopted, which not only reduces the phase current, but also improves the reliability. In this article, the topological structure, characteristics and principle of PMaSynR SG are systematically studied at first. Second, a simplified dq -axis equivalent magnetic circuit model is established, and the expressions of dq -axis inductance and permanent magnet flux linkage are derived on the basis of the basic parameter selection. Then, combined with parameter sensitivity analysis, the influence law of rotor structural parameters on antishort-circuit ability and electromagnetic performance is revealed. Finally, a 40 kW 24 000 r/min PMaSynR SG is designed and manufactured. The simulation and experimental results show that the proposed PMaSynR SG has excellent electromagnetic performance with the power density of 3.1 kW/kg and the efficiency of 94%, while the short-circuit current is only 59% of its rated value.