1,521 research outputs found
Sensorless flux-weakening control of permanent-magnet brushless machines using third harmonic back EMF
The sensorless control of brushless machines by detecting the third harmonic back electromotive force is a relatively simple and potentially low-cost technique. However, its application has been reported only for brushless dc motors operating under normal commutation. In this paper, the utility of the method for the sensorless control of both brushless dc and ac motors, including operation in the flux-weakening mode, is demonstrated
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
INVESTIGATION OF PERMANENT MAGNET SYNCHRONOUS MACHINES FOR DIRECT-DRIVE AND INTEGRATED CHARGING APPLICATIONS IN ELECTRIC VEHICLES
Electrified vehicles have proven to be potential candidates in the future for disrupting the automotive industry which is dominated by conventional gasoline vehicles. Electric vehicle (EV) technology has evolved rapidly over the last decade with new designs of EV drivetrain systems and components but no specific design has been able to serve as a solution that is affordable, reliable and performance-wise similar to existing gasoline vehicle equivalent. Extended driving range and overall cost of the vehicle still remain major bottlenecks. Understanding the state-of-the-art technologies and challenges in existing electric vehicle powertrain and charging systems, with major focus on permanent magnet synchronous machines & drives, this dissertation presents the following
Fault-Tolerant Control of a Flux-switching Permanent Magnet Synchronous Machine
Je jasnĂ©, ĆŸe nejĂșspÄĆĄnÄjĆĄĂ konstrukce zahrnuje postup vĂcefĂĄzovĂ©ho ĆĂzenĂ, ve kterĂ©m kaĆŸdĂĄ fĂĄze mĆŻĆŸe bĂœt povaĆŸovĂĄna za samostatnĂœ modul. Provoz kterĂ©koliv z jednotek musĂ mĂt minimĂĄlnĂ vliv na ostatnĂ, a to tak, ĆŸe v pĆĂpadÄ selhĂĄnĂ jednĂ© jednotky ostatnĂ mohou bĂœt v provozu neovlivnÄny. ModulĂĄrnĂ ĆeĆĄenĂ vyĆŸaduje minimĂĄlnĂ elektrickĂ©, magnetickĂ© a tepelnĂ© ovlivnÄnĂ mezi fĂĄzemi ĆĂzenĂ (mÄniÄe). SynchronnĂ stroje s pulznĂm tokem a permanentnĂmi magnety se jevĂ jako atraktivnĂ typ stroje, jejĂĆŸ pĆednostmi jsou vysokĂœ kroutĂcĂ moment, jednoduchĂĄ a robustnĂ konstrukce rotoru a skuteÄnost, ĆŸe permanentnĂ magnety i cĂvky jsou umĂstÄny spoleÄnÄ na statoru. FS-PMSM jsou pomÄrnÄ novĂ© typy stĆĂdavĂ©ho stroje stator-permanentnĂ magnet, kterĂ© pĆedstavujĂ vĂœznamnĂ© pĆednosti na rozdĂl od konvenÄnĂch rotorĆŻ - velkĂœ kroutĂcĂ moment, vysokĂœ toÄivĂœ moment, v podstatÄ sinusovĂ© zpÄtnĂ© EMF kĆivky, zĂĄroveĆ kompaktnĂ a robustnĂ konstrukce dĂky umĂstÄnĂ magnetĆŻ a vinutĂ kotvy na statoru. SrovnĂĄnĂ vĂœsledkĆŻ mezi FS-PMSM a klasickĂœmi motory na povrchu upevnÄnĂœmi PM (SPM) se stejnĂœmi parametry ukazuje, ĆŸe FS-PMSM vykazuje vÄtĆĄĂ vzduchovĂ© mezery hustoty toku, vyĆĄĆĄĂ toÄivĂœ moment na ztrĂĄty v mÄdi, ale takĂ© vyĆĄĆĄĂ pulzaci dĂky reluktanÄnĂmu momentu. Pro stroje buzenĂ© permanentnĂmi magnety se jednĂĄ o tradiÄnĂ rozpor mezi poĆŸadavkem na vysokĂœ kroutĂcĂ moment pod zĂĄkladnĂ rychlostĂ (oblast konstantnĂho momentu) a provozem nad zĂĄkladnĂ rychlostĂ (oblast konstantnĂho vĂœkonu), zejmĂ©na pro aplikace v hybridnĂch vozidlech. Je pĆedloĆŸena novĂĄ topologie synchronnĂho stroje s permanentnĂmi magnety a spĂnanĂœm tokem odolnĂ©ho proti poruchĂĄm, kterĂĄ je schopnĂĄ provozu bÄhem vinutĂ naprĂĄzdno a zkratovanĂ©ho vinutĂ i poruchĂĄch mÄniÄe. SchĂ©ma je zaloĆŸeno na dvojitÄ vinutĂ©m motoru napĂĄjenĂ©m ze dvou oddÄlenĂœch vektorovÄ ĆĂzenĂœch napÄĆ„ovĂœch zdrojĆŻ. VinutĂ jsou uspoĆĂĄdĂĄna takovĂœm zpĆŻsobem, aby tvoĆila dvÄ nezĂĄvislĂ© a oddÄlenĂ© sady. Simulace a experimentĂĄlnĂ vĂœzkum zpĆesnĂ vĂœkon bÄhem obou scĂ©nĂĄĆĆŻ jak za normĂĄlnĂho provozu, tak za poruch vÄetnÄ zkratovĂœch zĂĄvad a ukĂĄĆŸĂ robustnost pohonu za tÄchto podmĂnek. Tato prĂĄce byla publikovĂĄna v deseti konferenÄnĂch pĆĂspÄvcĂch, dvou Äasopisech a kniĆŸnĂ kapitole, kde byly pĆedstaveny jak topologie pohonu a aplikovanĂĄ ĆĂdĂcĂ schĂ©mata, tak analĂœzy jeho schopnosti odolĂĄvat poruchĂĄm.It has become clear that the most successful design approach involves a multiple phase drive in which each phase may be regarded as a single-module. The operation of any one module must have minimal impact upon the others, so that in the event of that module failing the others can continue to operate unaffected. The modular approach requires that there should be minimal electrical, magnetic and thermal interaction between phases of the drive. Flux-Switching permanent magnet synchronous machines (FS-PMSM) have recently emerged as an attractive machine type virtue of their high torque densities, simple and robust rotor structure and the fact that permanent magnets and coils are both located on the stator. Flux-switching permanent magnet (FS-PMSM) synchronous machines are a relatively new topology of stator PM brushless machine. They exhibit attractive merits including the large torque capability and high torque (power) density, essentially sinusoidal back-EMF waveforms, as well as having a compact and robust structure due to both the location of magnets and armature windings in the stator instead of the rotor as those in the conventional rotor-PM machines. The comparative results between a FS-PMSM and a traditional surface-mounted PM (SPM) motor having the same specifications reveal that FS-PMSM exhibits larger air-gap flux density, higher torque per copper loss, but also a higher torque ripple due to cogging -torque. However, for solely permanent magnets excited machines, it is a traditional contradiction between the requests of high torque capability under the base-speed (constant torque region) and wide speed operation above the base speed (constant power region) especially for hybrid vehicle applications. A novel fault-tolerant FS-PMSM drive topology is presented, which is able to operate during open- and short-circuit winding and converter faults. The scheme is based on a dual winding motor supplied from two separate vector-controlled voltage-sourced inverter drives. The windings are arranged in a way so as to form two independent and isolated sets. Simulation and experimental work will detail the driverâs performance during both healthy- and faulty- scenarios including short-circuit faults and will show the drive robustness to operate in these conditions. The work has been published in ten conference papers, two journal papers and a book chapter, presenting both the topology of the drive and the applied control schemes, as well as analysing the fault-tolerant capabilities of the drive.
Modeling And Analysis Of MultiâPhase Permanent Magnet Synchronous Machines: DirectâDrive Electric Vehicle Application
In commercially existing electric vehicles (EVs), power is transferred from the motor to the wheels through a fixed gear mechanical transmission system. However, such a transmission system contributes to a power loss between 2% to 20% of output power of the motor depending on the operating speed and torque of the motor. Therefore, by removing the transmission, a directâdrive EV configuration is obtained with lower component count, improved motor to wheel efficiency and frequency dependent losses. However, challenges in developing a single onâboard permanent magnet synchronous machine (PMSM) for such a configuration include high torque density, low torque ripple and high torque per permanent magnet (PM) volume. Therefore, this dissertation proposes a novel PMSM addressing the aforementioned challenges for a directâdrive application. Initially, the design targets, stator and rotor configuration and phase numbers of the PMSM are chosen to satisfy the requirements of a direct drive application. A novel torque and torque ripple model based on multiple reference frames is proposed, in which the torque ripple from spatial harmonics of flux, inductances and the time harmonics of stator currents are included. Using the analytical model, optimal slotâpole combination of the machine is selected based on adaptive gradient descent algorithm. A new consequent pole rotor topology is proposed to improve the torque density and torque per PM volume thereby reducing the usage of expensive rare earth magnets. The proposed PMSM with novel rotor is further improved in terms of torque density, losses and cost by performing an intensive structural optimization based on novel hybrid analytical model, finite element analysis and supervised learning. The optimized PMSM is then analyzed for various drive cycles and performance in terms of torque, speed and efficiency are discussed. A scaledâdown prototype of the proposed PMSM is developed and comprehensive experimental analysis in terms of torque ripple, torqueâspeed characteristics and efficiency are performed under different speeds and load conditions and are compared with the results obtained from proposed analytical model
Switched Flux Permanent Magnet Brushless Machines for Electric Vehicles
This thesis investigates different topologies of switched flux permanent magnet (SFPM) machines and variable flux (VF) methods for high speed applications.
Although several novel topologies of SFPM machines have been proposed and investigated recently, their torque-speed capability has not been studied systematically. Therefore, the torque-speed capability as well as the open circuit and electromagnetic performance of conventional SFPM machines with three different stator/rotor pole combinations, i.e. 12/10, 12/13 and 12/14, and three novel SFPM machine topologies, i.e. multi-tooth, E-core and C-core are analysed and investigated by the finite element (FE) method and experiments. Moreover, in order to improve the flux-weakening capability of these machines a variable flux method using flux adjusters (FAs) is employed and the corresponding electromagnetic performance of the machines are investigated, analysed and compared. Both FE and measured results show when the FAs are used the torque-speed capability of the three conventional machines can be improved significantly, while no improvement is shown in the three novel topologies primarily due to the large winding inductances.
The technique of using flux adjusters has been improved by reducing the number of FAs. Thus, a new mechanical variable-flux machine topology, which uses only half of FAs outside the stator at alternative stator poles, is proposed, developed and analysed. Open circuit results, electromagnetic performance and torque- and power-speed curves of the 12/10, 12/13 and 12/14 stator/rotor pole SFPM machines with alternative FAs are predicted and compared by 2D and 3D-FE, and experimentally validated.
Furthermore, a novel SFPM machine topology with radial and circumferential PMs is proposed, investigated and optimized. This topology reduces the stator flux leakage and offers high magnetic utilization. Moreover, this topology can also be developed as a mechanical variable flux machine.
Finally, three SFPM machines with variable flux techniques, i.e. mechanically movable flux adjusters (MMFA), mechanically rotatable permanent magnet set (MRMS) and hybrid excitation with backside DC coils (HEBC) are analysed. Their open circuit results and electromagnetic performance with emphasis on torque-speed characteristic are investigated and compared. Additionally, the required power to switch between flux weakening and strengthening states, flux weakening capability and permanent magnet demagnetization withstand capability are predicted, analysed and compared.
The influence of end-effect on the torque-speed capability in the conventional, multi-tooth, E-core and C-core SFPM machines is investigated. Measurements and 3D-FE are performed to obtain the torque-speed curve in order to validate the findings of the research. The 3D-FE predicted results match well with the measured results, while the 2D-FE predicted results are lower due to the high end-effect in the SFPM machines
Control Strategies for Open-End Winding Drives Operating in the Flux-Weakening Region
This paper presents and compares control strategies for three-phase open-end winding drives operating in the flux-weakening region. A six-leg inverter with a single dc-link is associated with the machine in order to use a single energy source. With this topology, the zero-sequence circuit has to be considered since the zero-sequence current can circulate in the windings. Therefore, conventional over-modulation strategies are not appropriate when the machine enters in the flux-weakening region. A few solutions dealing with the zero-sequence circuit have been proposed in literature. They use a modified space vector modulation or a conventional modulation with additional voltage limitations. The paper describes the aforementioned strategies and then a new strategy is proposed. This new strategy takes into account the magnitudes and phase angles of the voltage harmonic components. This yields better voltage utilization in the dq frame. Furthermore, inverter saturation is avoided in the zero-sequence frame and therefore zero-sequence current control is maintained. Three methods are implemented on a test bed composed of a three-phase permanent-magnet synchronous machine, a six-leg inverter and a hybrid DSP/FPGA controller. Experimental results are presented and compared for all strategies. A performance analysis is conducted as regards the region of operation and the machine parameters.Projet SOFRACI/FU
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
A novel modular stator hybrid-excited doubly salient synchronous machine with stator slot permanent magnets
This paper presents a novel modular stator hybrid-excited synchronous machine with stator slot permanent magnets (PMs). By regulating the field current, the magnetic field, and consequently the back electromotive force, as well as the average torque can be controlled. The existence of stator slot PMs alleviates the magnetic saturation and improves the flux regulation ratio. The frozen permeability method is employed to investigate the torque contributions by different magnetic sources. Possible stator and rotor pole combinations are illustrated, and the corresponding electromagnetic performances are evaluated with the finite-element method. It is revealed that 12-stator pole machines with 11- and 13-rotor poles exhibit superior average torque and lower torque ripple due to even-order harmonics elimination. Finally, a prototype with modular stator segments is manufactured to validate the analyses and simulations
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