Hiroya Sugimoto

Comparison of the Test Result and 3D-FEM Analysis at the Knee Point of a 60 kW SRM for a HEV

The maximum torque values in computer analysis and experiment in the switched reluctance motor (SRM), having competitive torque density and efficiency with respect to the rare-earth permanent magnet motor employed in the 2009 Toyota Prius, have been compared. The SRM is highly saturated to provide the maximum torque for a short time; thus, the torque value tends to have considerable error of 15% even in the 3D FEM analysis with respect to experimental result because of the incomplete material setting. A comparison of the flux-linkage and current is also provided for consideration. The results of the 2D-FEM and 3D-FEM analysis as well as a test machine are presented. The maximum torque in the 3D-FEM analysis is shown to be within errors of 5.0% with respect to that in the test machine.

Acoustic Noise and Vibration Reduction of SRM by Elimination of Third Harmonic Component in Sum of Radial Forces

A novel method to reduce an acoustic noise and the vibration of a switched reluctance motor has been proposed. In this method, driving current is a sum of dc, fundamental, the second- and the third-harmonic components. This driving current is determined to eliminate the third harmonic component in the sum of radial forces of the stator teeth. Consequently, an acoustic noise and a vibration are reduced. The effectiveness of the proposed method is confirmed by means of finite-element method and test machine experiments.

A Novel Parallel Motor Winding Structure for Bearingless Motors

A novel winding structure without separated suspension winding has been proposed for bearingless motors. The proposed winding structure basically has two parallel paths in three-phase motor windings. One three-phase winding path has a neutral point in general, but another three-phase winding path is connected to a suspension inverter, which injects currents for suspension force generation. Additional suspension windings are not needed in the stator slots, because the two parallel path windings are used for both torque and suspension force generation. In the proposed winding structure, speed induced voltages are cancelled each other so that no speed induced voltage is induced at suspension terminals.

Comparison of energy consumption of SRM and IPMSM in automotive driving schedules

Permanent magnets with rare earth materials are widely used in interior permanent magnet synchronous motors (IPMSMs) in Hybrid Electric Vehicles (HEVs). The recent price rise of rare earth materials has become a serious concern. A Switched Reluctance Motor (SRM) is one of the candidates for HEV rare-earth-free-motors. An SRM has been developed with dimensions, maximum torque, operating area, and maximum efficiency that all compete with the IPMSM. The efficiency map of the SRM is different from that of the IPMSM; thus, direct comparison has been rather difficult. In this paper, a comparison of energy consumption between the SRM and the IPMSM using four standard driving schedules is carried out. In HWFET and NEDC driving schedules, the SRM is found to have better efficiency because its efficiency is high at the high-rotational-speed region.

Principle of a Novel Single-Drive Bearingless Motor With Cylindrical Radial Gap

In this paper, a novel single-drive bearingless motor with cylindrical radial air-gap is proposed. The single-drive bearingless motor has only one set of three-phase windings. It generates both torque and axial suspension force independently with only one three-phase inverter and one displacement sensor. Therefore, this single-drive bearingless motor has the advantages of low cost and small size. Only axial direction z-axis is actively positioned. The other axes, radial movements x and y, and tilting movements θ∞ and θy, are passively stable. In the proposed motor, the rotor is a cylindrical permanent magnet magnetized in a radial parallel direction. The stator consists of six C-shaped cores and one set of three-phase windings. The principles of the suspension force and torque generations by the dand q-axis currents, respectively, are shown. The proposed machine was fabricated and tested only to confirm the principles. In the experiments, start-up was successfully achieved. In an acceleration test up to 3600 r/min, stable magnetic suspension and speed regulation by the d- and q-axis current regulations were confirmed.

Basic Characteristic of the Multi-Consequent-Pole Bearingless Motor

For low speed applications, such as rotating and swing stages, a multi-consequent-pole bearingless motor is proposed. This paper describes basic characteristics of a multi-consequent-pole bearingless motor. Unlike conventional bearingless motors, suspension force generating on consequent-pole type is independent of rotor rotational position. Thus, multi-pole rotors such as 40, 44, and 46 poles are easy without a penalty of high precision in rotating angular position detection. Basic design of pole number selection is discussed with suspension force and average torque capability. Magnetic force error can be reduced with multi-pole rotor configuration. A test machine has been constructed and driven by a compact drive and a CPU unit.

Comparing Electric Motors: An Analysis Using Four Standard Driving Schedules

Permanent magnets with rare-earth materials are widely used in interior permanent magnet synchronous motors (IPMSMs) in hybrid electric vehicles (HEVs). The recent price increase in rare-earth materials has become a serious concern. A switched reluctance motor (SRM) is one of the candidates for HE V rare-earth-free motors. An SRM has been developed with dimensions, maximum torque, operating area, and maximum efficiency that all compete with the IPMSM. The efficiency map of the designed SRM is different from that of the IPMSM; thus, direct comparisons have been rather difficult. In this article, a comparison of the energy consumption between the SRM and the IPMSM using four standard driving schedules is carried out. In the Highway Fuel Economy Driving Schedule (HWFET) and the New European Driving Cycle (NEDC), the SRM is found to have better efficiency because its efficiency is high at the high rotational speed region.

Design and Basic Characteristics of Multi-Consequent-Pole Bearingless Motor With Bi-Tooth Main Poles

A multi-consequent-pole bearingless motor which is adapted to low speed rotation is presented. The bearingless motor can be used in swinging stages (or platforms) under specific conditions. Two degrees of freedom (2DOF) are actively controlled in the radial x-y directions. A gap sensor is required to control each DOF. Although 2DOF bearingless motors almost have a flat rotor so that axial length of the rotor is small, the device needs gap sensors and its target. In this paper, a novel stator structure is proposed and a design procedure considers the installation of the gap sensors on the stator. Three dimensional finite element analyses are carried out. An amplitude pulsation and a direction error of the radial suspension force with respect to the rotor rotational angular position are evaluated. Two machines with a conventional stator and the proposed stator are tested and compared. It is shown the proposed machine has beneficial performance by experimental verification.

Acoustic Noise Reduction of Switched Reluctance Motor With Reduced RMS Current and Enhanced Efficiency

A general condition is derived for the reduction of stator vibrations in multiphase switched-reluctance motors (SRMs) through current regulation in a low-torque and low-speed region. By exploring a wider space of solutions than had previously been examined, optimized solutions are found which simultaneously minimize acoustic noise and vibration, and also minimize qualities such as copper loss, peak current, or torque ripple. In particular, the current profile is represented as a Fourier sum of three harmonics and the phase shift of these harmonics is examined. Experiments show a reduction of motor losses by 10% to 20% relative to previous attempts at proposed waveforms, while achieving a similar reduction in acoustic noise and vibration. In general, current profiling for noise reduction resulted in reduced efficiency; however, in this paper, it was found that motor efficiency can be enhanced relative to conventional square waveform current regulation, while reducing acoustic noise and vibration significantly.

Energy Efficiency of SR and IPM Generators for Hybrid Electric Vehicle

A new switched reluctance (SR) generator was designed for possible application in hybrid electric vehicles. The proposed generator was designed to be mostly competitive with the target interior permanent-magnet (IPM) generator currently used in mass-produced hybrid vehicles. The energy efficiencies of the SR and IPM generators were compared in typical driving cycles, such as US06, HWFET, and UDDS modes. We found that the energy efficiency of the SR generator was close to the IPM generator in high-speed driving cycles because the SR generator has no iron loss during the generator idling period due to the fact that it has no PM.