open circuit fault

Six-phase motors are becoming more popular because of their advantages such as lower torque ripple, better power distribution per phase, higher efficiency, and fault-tolerant capability compared to the three-phase ones. This paper presents the fault-tolerant capability analysis of a symmetrical six-phase induction motor equipped with distributed, conventional concentrated, and pseudo-concentrated windings under open-circuit fault scenarios. For further investigation, different load types such as constant-speed, constant-torque, and constant-power are applied to the motor. Two concepts of magnetic and physical phase separations are introduced as factors affecting the motor reliability. Analytically, these factors give an insight into how the pseudo-concentrated winding could be a fault-tolerant alternative. Moreover, five parameters such as the change of output power, power loss, power factor, efficiency, and expected load loss are considered as the fault-tolerant capability parameters to evaluate the windings reliability. The aforementioned parameters are reported using the finite element analysis for different fault scenarios and different load types. Although the baseline motor dimensions are not optimized for applying the pseudo-concentrated winding, the pseudo-concentrated shows a promising performance with high fault-tolerant capability.

The modular multilevel converter (MMC) is a favored topology in the industry, but its reliability is at risk with an increase in the number of sub-modules (SMs) due to a rise in switching components. The essential need for maintaining capacitor voltage balance in each arm leads to increased complexity and cost, as numerous voltage sensors are required. This study introduces an innovative approach to minimize the number of voltage sensors by employing an enhanced algorithm for open-circuit fault detection in switches. The proposed scheme organizes each arm into groups, each containing two SMs and one voltage sensor, aiming to reduce the overall sensor count. A novel fault detection mechanism is presented, identifying open-circuit faults by comparing group output voltages in healthy and defective conditions. The capacitor voltage estimation algorithm in the sensor reduction scheme is noted for its simplicity compared to other methods. The effectiveness of these methods is validated through simulations and experimental implementations across diverse scenarios, affirming their reliability.

Fault-Tolerant Hybrid Excited Axial Field Flux-Switching (FT-HEAFFS) motor is a new type of doubly salient stator-type permanent magnet motor, which combines the advantages flux switching motor and hybrid excitation motor. This motor has compact structure, high power density, high efficiency and strong anti-demagnetization capability. The additional excitation winding makes the air gap magnetic field adjustable, which can increase the output torque and extend the speed range. It is suitable for use in the system of frequency conversion and speed regulation of electric vehicles. To improve the performance of the fault-tolerant-hybrid excitation axial field flux-switching (FT-HEAFFS) motor and attain the minimum copper loss, a fault-tolerant control method based on model predictive control algorithm is proposed. Considering a 6 stator slots/13- rotor poles FT-HEAFFS machine as the control object, under the open circuit failure of single-phase winding, the minimum cropper loss fault-tolerant method based on the model predictive torque control (MPTC) and direct torque control are studied and analysed, respectively. The feasibility and effectiveness of the proposed fault-tolerant control method are verified. The research results showed that both methods could make the speed, torque and stator flux-linkage almost unchanged, ensuring the stable operation of the system. Compared with direct torque control, the model predictive flux control had smaller flux-linkage ripple before and after the open circuit failure.