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This paper presents efficiency improvement of switched reluctance motors (SRMs) by stepped-skewing rotor (SSR). The cross sectional configuration of the SRM tested including size and shape of salient poles is almost same as those of a conventional SRM. The tested SRM is divided into 3 stacks, and only rotor is skewed. The skew angle has been designed to reduce both of torque ripple and radial force...
Sensorless position estimation based on signal-injection methods always requires a resistance- or inductance-based anisotropy. Therefore, a short-circuited electrical winding can be attached on the rotor. As will be derived in this paper, this method leads to both a resistance- and inductance-based saliency. By an experimental test setup, both saliencies are analyzed and compared towards their accuracy...
SRMs, switched reluctance motors, are being expected as an excellent candidate for power sources in harsh environments due to the simple structure. In spite of many methods proposed to eliminate the rotor position sensor, which is needed to commutate the current correctly but not compatible with harsh environments, no successful sensor-less method has been seen so far. The method proposed in this...
This paper reviews recent technical trends in variable flux motors. Permanent magnet motor is a major component to realize high torque density with keeping high efficiency. However, when high speed revolution is required for further miniaturization, as well as the large torque in the low speed region, the flux yielded by the permanent magnet encounters a serious trade-off, i.e. the former needs less...
In this paper, design and analysis of interior permanent magnet synchronous motor for electric vehicle bus propulsion is performed based on Finite Element Method. As the increase of the advanced application which requires precise control, the inverter is regarded as requisite for controlling electric machines. In addition multi-domain co-simulation is important to consider the inter-linking effect...
This paper describes fast analytical model for computation of the switched reluctance machine's (SRM) nonlinear magnetization characteristic and torque lookup table. The flux-tube and the gage-curve methods are used to develop this fast analytical model. Presented model is used for computation of the magnetization characteristic and torque lookup table of three and four-phase SRMs. The simulation...
A Switched Reluctance Motor (SRM) has been designed with outer dimensions, maximum torque, operating area, and maximum efficiency identical to the rare-earth PM motor used in the Toyota Prius. However, an SRM has salient poles in the rotor; thus, additional windage loss is generated. In this paper, estimation of the windage loss of the SRM is carried out. Then, a comparison to the machine test result...
This paper presents a new start-up method from standstill to a sensorless control for surface permanent magnet synchronous motor (SPMSM). To estimate the rotor position of SPMSM from the measured induced voltage, a DC current adds to the motor and nonlinear observer is introduced to the motor torque equation while the motor is vibrating. To achieve the start-up smoothly, first order induced voltage...
This paper presents a novel control strategy to stably support the rotor shaft when a bearingless motor (BELM) based on d-q axis current control is driven under loaded condition. In this type BELM, the magnitude and direction of the suspension force are unfortunately varied depending on the rotor rotation, which causes the unstable rotor levitation during the motor operation. Thus, the compensation...
Reaction wheels (RWs) for small satellites with active magnetic bearings allowing for ultra-high-speed operation show advantages in angular momentum density over ball bearing RWs with limited speed according to scaling laws developed in this paper. A reaction wheel demonstrator design based on a novel dual hetero/homoploar, slotless, self-bearing, permanent-magnet synchronous motor concept with a...
A permanent magnet hybrid type axial magnetically levitated motor is proposed. The motor consists of a spherical permanent magnet and an axial type bearing-less motor that has tilt control function. The rotor has two permanent magnets on one side, and the motor stator has eight poles, which include eight concentrated windings. The operating principle was investigated by numerical analysis. It was...
For high speed bearingless disk drives, certain topologies are advantageous. The authors have published works on a bearingless disk drive for high speeds which is characterized by a slotless stator and a toroid winding set. Several different variations of this setup are imaginable. The ones which this work focuses on are the variation of the number of phases, of the number of coils, and of the applied...
This work introduces a novel bearingless slice motor design, the bearingless flux-switching slice motor. In contrast to state-of-the-art bearingless slice motors the rotor in this new design does not possess any permanent magnets. This offers advantages for disposable rotor devices for instance in the medical industry and extends the range of bearingless slice motors towards high temperature applications...
Advanced control techniques for wound rotor synchronous machines need precise machine models. Often a simple fundamental wave model is used to design the control algorithms. Using such a model, it is not possible to account for non-ideal effects that distort the control algorithm. Therefore a general machine model is derived by extending classical winding function theory. This analytical machine model...
In general, the in-wheel type permanent magnet synchronous motor (PMSM) for electric city commuters uses powerful rare earth permanent magnets (PMs). However, the employment of the rare earth PMs should be reduced due to high prices. Therefore, it is important to develop an in-wheel PMSM that does not use the rare earth PMs. We proposed 5kW in-wheel type axial gap motor that can generate high torque...
This paper proposes a new sensorless vector control method for energy-efficient and wide-speed-range drives of permanent-magnet synchronous motors. The proposed sensorless method is endowed with all of the following functions: 1) wide-speed-range drive under voltage limit, 2) current limitation, 3) high-efficiency. These functions are realized in a very simple manner and can operate adaptively in...
This paper presents a comparison study of various motors for application to an electric vehicle (EV) and the potentiality of a ferrite magnet motor as a candidate for rare-earth-less motor for an EV. The rotor shape of the proposed ferrite magnet motor is based on a spoke-type shape. Further, we developed two types of prototypes: one has a large magnetic torque equivalent to a conventional rare-earth...
A high-efficiency motor is required in order to address recent environmental issues. Permanent magnet synchronous motors (PMSMs) are widely used because of their high efficiency. However, even higher efficiency is required in order to reduce the power consumption of motors. The structures of PMSMs using a powder magnetic core are considered. Since the powder magnetic core has very little eddy current...
A promising topology to interconnect the wind power plants is proposed. Advantages of series-connected system over ordinary parallel system are first discussed, and control strategies for the series-connected system are studied to realize an optimum use of the wind energy. The dynamic performances of the series-connected system are investigated through simulation and experiments. An effective method...
This paper proposes a novel noise reduction method by injected frequency control for position sensorless control of permanent magnet synchronous motor (PMSM). The proposed method reduces acoustic noise caused by injected high-frequency voltage without reducing the accuracy of rotor position estimation. The proposed method is verified by numerical simulations and experiments using a 0.8kW-PMSM.
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