Design and construction of a laboratory bench system for the teaching and training of engineers on diagnostics of permanent magnet motors

Permanent magnet synchronous motors PMSM are widely used in industry due to their higher torque and higher power to volume ratio. Moreover they have a better dynamic performance compared to the motors with electromagnetic excitation. Despite its robustness electrical, mechanical and magnetic faults has been described. It has led to the development of specific diagnostic systems for such machines. These systems are constantly evolving according to the literature. In this situation of increasing use of PMSM it is necessary to teach and train professionals in diagnostic techniques. This paper describes the design process of an experimental bench on which can be studied all types of faults associated with the PMSM operation. The design of a PMSM prototype, which is the most important equipment of this bench, is described in more detail

A high-speed permanent-magnet machine for fault-tolerant drivetrains

This paper details the design considerations of a permanent magnet (PM), three phase, high speed, synchronous machine for fault tolerant operation. A multidisciplinary approach to the optimal design of the machine is adopted targeted at minimising the additional losses resulting from faulty operating conditions and accounting for the remedial control strategy implemented. The design of a closed slot, 6 slots, 4 pole machine is presented. The machine is prototyped and tested to validate the analytical-computational performances predicted in the design and analysis stage under healthy and faulty condition

Six-Phase Fractional-Slot-per-Pole-per-Phase Permanent-Magnet Machines With Low Space Harmonics for Electric Vehicle Application

This paper discusses the development of new winding configuration for six-phase permanent-magnet (PM) machines with 18 slots and 8 poles, which eliminates and/or reduces undesirable space harmonics in the stator magnetomotive force. The proposed configuration improves power/torque density and efficiency with a reduction in eddy-current losses in the rotor permanent magnets and copper losses in end windings. To improve drive train availability for applications in electric vehicles (EVs), this paper proposes the design of a six-phase PM machine as two independent three-phase windings. A number of possible phase shifts between two sets of three-phase windings due to their slot-pole combination and winding configuration are investigated, and the optimum phase shift is selected by analyzing the harmonic distributions and their effect on machine performance, including the rotor eddy-current losses. The machine design is optimized for a given set of specifications for EVs, under electrical, thermal and volumetric constraints, and demonstrated by the experimental measurements on a prototype machine

A Fault Tolerant Machine Drive Based on Permanent Magnet Assisted Synchronous Reluctance Machine

A fault tolerant machine drive based on permanent magnet assisted synchronous reluctance machine (PMA SynRM) is proposed and investigated for applications where reliability and safety are crucial. In order to achieve enhanced fault tolerant capability, the risk of permanent magnet field that cannot be turned off under fault conditions is minimized without compromise in torque density and efficiency. This is achieved by employing a synchronous reluctance rotor topology with embedded permanent magnets. Three independent, segregated 3-phase windings are configured to ensure isolation and non-overlapping between the three 3-phase winding sets. Each 3-phase winding set is driven by a standard 3-phase inverter to facilitate fast integration and cost reduction. The machine behavior under various fault conditions has been evaluated by finite element (FE) simulations. A 40kW prototype was designed, constructed and tested. The test results demonstrate the performance and excellent fault tolerant capability of the proposed drive system under various faults, including open circuit and short circuit conditions

Desarrollo de un sistema de diagnóstico de fallas en la dirección asistida eléctrica de automóviles

Actualmente el índice de tránsito vehicular del parque automotor está creciendo sustancialmente y con ello también los altos índices de accidentes de tránsito. Si bien muchos de dichos accidentes se deben a factores humanos, es importante considerar que estos vehículos están propensos a fallas en sus sistemas debido a múltiples factores como son, la falta de mantenimiento, el corto tiempo de vida de los elementos del sistema vehicular, el uso continuo, las condiciones de las carreteras, etc. Es por ello que la detección oportuna de estas fallas permitirá reducir drásticamente pérdidas de vidas humanas, costosos gastos de recambio de piezas y sistemas, daños al medio ambiente a causa de malos funcionamientos, etc. Un elemento crítico de los vehículos actuales es el del sistema de dirección asistida que permite reducir el esfuerzo del conductor para maniobras de orientación del vehículo reduciendo los impactos en el volante y garantizando una adecuada estabilidad del vehículo. En esta tesis se aborda el diseño de un sistema de diagnóstico de fallas para el sistema de dirección asistida de un vehículo de categoría M1 (categorizado por el Ministerio de Transportes) con el objetivo de diagnosticar las fallas más relevantes de este sistema. El desarrollo de la tesis, se inicia con un estudio del modelamiento matemático del sistema de dirección asistido eléctrico (EPS por sus siglas en inglés). Posteriormente, se diseña el sistema de diagnóstico basado en 2 etapas. La primera es la detección de fallas, la cual está basada en la generación de Relaciones de Redundancia Analítica. Como segunda etapa, se diseña el sistema de diagnóstico de fallas utilizando Redes Neuronales Artificiales a fin de poder reconocer los tipos de fallas de manera más robusta ante las perturbaciones. Las pruebas de validación del sistema de diagnóstico se realizan utilizando los software de ingeniería Matlab y Carsim. Con estas pruebas se valida el adecuado funcionamiento del sistema de diagnóstico de fallas propuesto en un vehículo de categoría M1. Finalmente se propone un sistema para implementación en un vehículo real utilizando la plataforma Arduino.Tesi

Design of a fault-tolerant IPM motor for electric power steering

none3This paper deals with the design of an interior permanent magnet (IPM) motor for power steering. Such an application requires an imperative fault-tolerant capability that is obtained by means of a redundant solution with two motors on the same shaft. A ball-screw system converts the rotating movement into the linear movement of the steering rack. In addition, the IPM motor has to exhibit very low braking torque after a short-circuit fault. Useful relationships between the maximum braking torque and the motor parameters are found and used in the design of the motor.noneN. Bianchi;M. D. Pre;S. BolognaniBianchi, Nicola; DAI PRE', Michele; Bolognani, Silveri

Design of a fault-tolerant IPM motor for electric power steering

Abstract\u2014This paper deals with the design of an interior per- manent magnet (IPM) motor for power steering. Such an ap- plication requires an imperative fault-tolerant capability that is obtained by means of a redundant solution with two motors on the same shaft. A ball-screw system converts the rotating movement into the linear movement of the steering rack. In addition, the IPM motor has to exhibit very low braking torque after a short-circuit fault. Useful relationships between the maximum braking torque and the motor parameters are found and used in the design of the motor

Feasibility of high frequency alternating current power distribution for the automobile auxiliary electrical system

This study investigates the feasibility and potential benefits of high frequency alternating current (HFAC) for vehicle auxiliary electrical systems. A 100Vrms, 50kHz sinusoidal AC bus is compared with 14V DC and 42V DC electrical systems in terms of mass and energy efficiency. The investigation is focused on the four main sub-systems of an on-board electrical network, namely: the power generation, power distribution, power conversion and the electrical loads. In addition, a systemlevel inquiry is conducted for the HFAC bus and a comparable 42V DC system. A combination of computer simulation, analytical analysis and experimental work has highlighted benefits for the HFAC power distribution sub-system and for low-torque motor actuators. Specifically, the HFAC conductor mass is potentially 70% and 30% lighter than comparable 14V DC and 42V DC cables, respectively. Also, the proposed cable is expected to be at least 80% more energy efficient than the current DC conductor technology. In addition, it was found that 400Hz AC machines can successfully replace DC motor actuators with a rated torque of up to 2Nm. The former are up to 100% more efficient and approximately 60% lighter and more compact than the existing DC motors in vehicles. However, it is argued that the HFAC supply is not feasible for high-torque motor actuators. This is because of the high energy losses and increased machine torque ripple associated with the use of HFAC power. The HFAC power conversion sub-system offers benefits in terms of simple power converter structure and efficient HFAC/DC converters. However, a significant limitation is the high power loss within HFAC/AC modules, which can be as high as 900W for a 2.4kW load with continuous operation. Similar restrictions are highlighted for the HFAC power generation sub-system, where up to 400W is lost in a 4kW DC/HFAC power module. The conclusion of the present work is that the HFAC system offers mass and energy efficiency benefits for the conventional vehicle by leveraging the use of compact lowtorque motor actuators and lightweight wiring technology

A fault tolerant motor drive for electric power steering systems

Ph. D. ThesisElectric machines are becoming increasingly prevalent in safety critical transport applications, whether as both the main drive components or in auxiliary systems. An automotive electric power steering system is an auxiliary drive system that replaces conventional hydraulic systems due to its high reliability, low size and cost, high security, good road feeling, control stability and operates when required. Permanent magnet AC motors are one of the most favourable choices for this application due to their high torque and power density, low torque ripple and low acoustic noise. The main challenge with PM machines in a fault situation is the drag torque resulting from short-circuit currents. These currents are induced by fluxes from the permanent magnets. This research investigates a 12 slot 8 pole interior permanent magnet motor. It investigates different winding arrangements and winding connections for a dual-lane system and compares them to a single-lane system. The baseline motor has 4 coils in parallel per phase for a single-lane system, and 2 coils per lane per phase for a dual lane system. In a dual-lane system, the stator coils can be connected in three different arrangements which are interleaved, half-half and quarter. The half-half arrangement is the best compromise for the baseline motor, as it produces the highest average torque and medium torque ripple under a symmetrical 3-phase short-circuit fault. A modular winding was implemented on the baseline motor’s stator to reduce drag torque and torque ripple under faulted conditions. However, the stator core saturates leading to higher torque ripple and a torque drop under normal conditions. Therefore, a new modular stator was developed to overcome saturation. This gave higher torque capability due to the wider wound teeth tooth arc used, and hence a higher winding factor. The fault-tolerance of the modular stator is significantly improved due to the higher coil inductance and lower drag torque. In the constant power region, the power is significantly compromised. The knee point speed is affected as the high q-axis inductance limits the availability of the supply voltage at a lower speed. Various approaches are presented that aim to reduce the overall motor inductance or only the q-axis inductance to recover the power drop. Firstly, the baseline motor’s rotor is shaped to reduce the q-axis flux. This is not feasible as the power cannot be fully recovered and the torque ripple becomes considerably high. Secondly, the number of turns is reduced, and the input current is increased to keep the MMF input unchanged. Using this approach, the power drop is fully recovered, but a thicker wire diameter should be used for winding, and higher input current means higher ECU losses. Finally, a novel SPM motor is presented. This overcomes the constant power region torque drop through reducing the q-axis inductance. Compared to the baseline motor, the power and torque density of the motor are considerably higher. The overall stator and rotor stack lengths are shorter. As the end-windings are bigger that affects the motors overall length which might also affect the motor size and packaging. The coils and motor lanes are segregated which helps in reducing the torque ripple under faulted condition. At lower speeds the average torque available within a short circuit or single MOSFET fault within the drive stage is similar to that of the baseline motor. At higher speeds the SPM offers greater average torque capability than the baseline motor.ZF Group, Newcastle Universit