For the propose of increasing the reliability in hostile environment, techniques of fault diagnosis have been reported for three-phase voltage source inverter (VSI). Based on the average current Park's Vector method, this paper proposes a fuzzy-based fault diagnosis method for the VSI in the three-phase permanent-magnet synchronous motor drive. By utilizing the phase current information, the fault symptom variables are calculated by using the average current Park's Vector method. The fuzzy logic approach is applied to process the fault symptom variables and get the faulty information of power switches. Compared with other fuzzy logic methods, the fuzzy logic design, fuzzy inputs and fuzzy rules are different. The proposed fault diagnosis method can detect and locate not only the single or multiple open-circuit faults but also the intermittent faults in power switches, which can improve the reliability of the motor drive system. The effectiveness of the proposed method is validated by both simulation and experiments.

Electrical machines and drives keep moving away from traditional technologies such as brushed machines and wound field machines towards lighter, ‘easier to maintain’ machines. A very interesting aspect is that certain transport applications, especially the aerospace industry, still favour the classical wound field machine for its main generating system such as the Boeing 787. This paper focuses on investigating this particular trend by presenting a detailed overview of historical power generation systems on aircraft. This paper compares the current state of the art of wound field machines with other generator families. The results of this analysis are then projected into the needs of the electrical power generation and distribution system on aircraft. While power density is a major objective for any aerospace application, however the extra benefits associated with wound field systems are still essential in modern aircraft. The paper then focuses on the main challenges for improving power density of wound field machines. Recommendations, opportunities and improvements related to wound field machines are discussed. In conclusion, if robust designs for higher speed wound field generators were consolidated, it would be very probable that these classical machines might still be implemented on future MEA platforms.

Current sensing techniques with reduced number of sensors attract a high interest from industry, for the possibility of cost reduction and sampling mismatch reduction. This paper puts forward a new single current sensor (SCS) method for a permanent magnet synchronous motor (PMSM) three-phase current reconstruction, with a novel hybrid pulse width modulation technique introduced. This method is implemented by changing the position of SCS from dc bus to a current branch, and a modified space vector pulse width modulation (SVPWM) technique is employed to realize the phase current reconstruction. Compared with traditional SCS control methods, the proposed method can relieve the measurement dead-zones (MDZs) at sector boundary region without introducing extra compensation algorithms. Besides, this method can be realized not only with a single hall-effect current sensor but also a single shunt resistor, which further expands the applications and increases the system reliability as well. This method is also available in other motor control with a two-level three-phase PWM Voltage Source Inverter (VSI) topology. The accuracy and feasibility of the proposed method is validated by the simulation and experimental results.

Modern electrical machines employed in transportation applications are required to provide high performance in terms of power (and torque) density. At the same time, being these applications safety-critical, a significant level of reliability and/or fault tolerance is expected. Among all the factors which can compromise motors reliability, partial discharges (PDs) inception is one of the most crucial, in particular for low voltage, random wound machines. This article presents an extensive experimental investigation on PDs in electrical machines for aerospace applications. Measurements are carried out using both sinusoidal and fast-rising pulses in a representative aerospace environment, emulating the typical ambient conditions encountered throughout a commercial aircraft mission, and beyond (i.e., down to 30 mbar). As a main result of the investigation, it is proved that electrical machines employed for actuating primary flight control surfaces feature a higher risk of PDs inception. Therefore, their insulation system demands an extremely careful design.

High-speed permanent magnet synchronous machine (PMSM) can provide high power density and high efficiency, which is often highly desirable in high performance applications. A multi-physics optimization program based on the multi-objective genetic algorithm was developed in this paper, to achieve a tradeoff solution between the electromagnetic, mechanical, and thermal aspects. First, the parametric electromagnetic model was modeled based on the finite-element method, and then a thermal network model and an analytical mechanical model to determine the thickness of the magnet and the sleeve were developed and merged within a design cycle of the machine, in an effort to attain the target performances of 20 kW/kg at 20,000 r/min for a 2 MW PMSM. Optimization results indicated that a final design with eight poles and 48 slots could obtain a comprehensive performance between power density and efficiency, and the performance satisfied all the requirements.

Although many permanent magnet synchronous motors (PMSMs) are used as the driving source for aerospace applications, the motor and converter are not integrated. This leads to large volume and low power density of the system. This article proposes an SiC-based integrated modular motor drive (IMMD) as a potential solution, in which the SiC converter is placed at the end of the stator core of the motor. The converter is directly connected to the end-turn windings of the motor so as to reduce the wiring cable losses, with the motor and converter being cooled by an integrated water-cooled housing, significantly reducing the weight of the system and improving the power density. First, the topology of a five-phase IMMD is briefly introduced. Then, the influence of the number of slots on the output performance of the motor is analyzed with the aim of improving the power density of the system. Because the system integration will cause the loss density of the motor to sharply increase, this will thereby cause the local temperature of the IMMD to be higher. A detailed analysis and calculation of the thermal design will be required to improve the reliability of the system in high-temperature environments. The skewed rotor method is adopted so that the torque ripple of the fractional-slot motor is suppressed in the high-speed region. The results show that these methods can increase the power density of the IMMD and expand the speed range of the motor so as to meet the needs of different stages during the whole flight of more electric aircraft.