Yoshihiro Miyama

PWM Carrier Harmonic Iron Loss Reduction Technique of Permanent-Magnet Motors for Electric Vehicles

This paper investigates a method to increase fuel economy of motors for an electric vehicle (EV) traction system. The low-torque region of an EV motor is frequently used in everyday urban driving and in fuel economy measurement. Pulsewidth modulation (PWM) carrier harmonic iron loss accounts for a high percentage of total loss for EV motors in this region. This paper reveals the relationship between phase current and carrier harmonic iron loss for a permanent-magnet synchronous motor (PMSM) in the low-torque region. Thus, a novel carrier harmonic loss reduction technique is proposed and applied to two sets of three-phase windings for a concentrated winding PMSM. The loss is successfully reduced in a 70-kW EV motor as well as a two-dimensional finite-element method (2-D-FEM) calculation. The efficiency of the developed motor is calculated and compared with that of a conventional motor in the JC08 mode driving cycle.

Variable characteristics technique on permanent magnet motor for electric vehicles traction system

A traction motor system of electric vehicles (EVs) requires wide torque-speed operation range, high efficiency, and low torque ripple according to its driving point. To achieve the requirements without increasing motor size, a novel variable characteristics motor system is proposed in this paper. A winding structure is studied to reduce unprofitable conductor which makes conduction loss. The developed system is applied 48-slot 8-pole permanent magnet synchronous motor (PMSM). The motor has structural full-pitch distributed winding with 12 open-end windings connected to insulated 12 full-bridge inverter. The developed motor simulates 4 types of winding mode, and each characteristic are calculated based on static two dimensional finite element analysis (2D-FEA). The calculated results show increase torque-speed operation range, higher efficiency, and lower torque ripple by selecting appropriate winding mode.

MATRIX motor with individual winding current control capability for variable parameters and iron loss suppression

This paper describes a novel motor-drive system which includes the multi-phase open-end windings for an individual winding current control in order to realize the variable parameters. Each armature winding is connected with the insulated full-bridge inverter for the arbitrary excitation waveform. The proposed construction can extend the operating area and can distribute the high efficiency area. Furthermore, the proposed multi-phase drive can suppress the harmonic iron loss under the flux weakening operation because the individual control can regulate the instantaneous flux density in each stator tooth even though the motor consists of the full-pitch distributed winding. In this paper, the down size model was designed to confirm the principle. It was shown that the downsize model can expand the operating range, can distribute high efficiency area, and can suppress the iron loss by the controlled flux density in each stator tooth by some simulation and experimental results.

PWM carrier harmonic iron loss reduction technique of permanent magnet motors for electric vehicles

This paper investigates a method to increase fuel economy of motors for an electric vehicle (EV) traction system. The low-torque region of an EV motor is frequently used in everyday urban driving and in fuel economy measurement. Pulsewidth modulation (PWM) carrier harmonic iron loss accounts for a high percentage of total loss for EV motors in this region. This paper reveals the relationship between phase current and carrier harmonic iron loss for a permanent-magnet synchronous motor (PMSM) in the low-torque region. Thus, a novel carrier harmonic loss reduction technique is proposed and applied to two sets of three-phase windings for a concentrated winding PMSM. The loss is successfully reduced in a 70-kW EV motor as well as a two-dimensional finite-element method (2-D-FEM) calculation. The efficiency of the developed motor is calculated and compared with that of a conventional motor in the JC08 mode driving cycle.

Wide range operation by low-voltage inverter-fed MATRIX motor with single-layer distributed winding for automobile traction motor

This research proposes a novel low-voltage inverter-fed motor drive with variable characteristics achieved through the individual winding current control for the automobile traction motor. The independent armature winding with low-voltage inverters can improve the total efficiency by reducing the converter losses. Furthermore, the motor can expand the operating range since the inverters are able to change their connections to different coils groups of the armature winding. In this paper, the down size model was designed to verify the principle. It was confirmed that the principle model can extend the operating range and can expand the high efficiency area by FEA and experimental results.

Wide Speed Range Operation by Low-Voltage Inverter-Fed MATRIX Motor for Automobile Traction Motor

This research proposes a novel low-voltage inverter-fed motor drive with variable parameters achieved through the independent armature winding for the automobile traction motor. The independent armature winding with low-voltage inverters can improve the total efficiency by reducing the converter losses. The inverters are able to change their connections to different coils groups of the armature winding in order to achieve the wide operating range. The voltage equation of each mode can be shown by using the transformation matrix when the winding connection is changed. Thus, the proposed motor is called the MATRIX motor. In this paper, the downsized model was designed to verify the principle. The principle model is able to achieve four motor parameters. It was confirmed that the principle model could extend the operating range and could achieve the high-efficiency driving in wide speed range. Furthermore, the novel winding reconfiguration method is proposed that not only avoids the surge voltage, but also compensates the torque reduction during the winding reconfigurations.

Vibration reduction by applying carrier phase-shift PWM on dual three-phase windings permanent-magnet synchronous motor

This paper investigates a method of reducing vibration property of a permanent-magnet synchronous motor (PMSM) with dual three-phase windings, especially focusing on carrier harmonic component. Carrier phase shift pulse width modulation (PWM) which makes any difference between PWM carrier phase of 1st winding and 2nd winding, is applied to 24-slot 20-pole PMSM. A tested motor is manufactured and measured results reveals the vibration and sound pressure can be approximately halved at around twice of the carrier frequency when the carrier phase is π/2 radian between each three-phase winding compared to conventional in-phase carrier PWM.

Study of switching method for MATRIX motor realizing variable characteristic

This research proposes a novel low-voltage inverter-fed motor drive with variable characteristics which is achieved through the individual armature winding current control for the automobile traction motor. The independent armature winding with low-voltage inverters can improve the total efficiency by reducing the converter losses. Furthermore, when the inverters are able to change their connections to different armature windings groups, the motor can expand the operating range. This paper describes a novel circuit topology for winding reconfiguration and switching method to suppress the surge voltage without the snubber circuit. It is confirmed that proposed circuit topology can change winding connections without the surge voltage by simulation results and experimental results.

Larger torque production strategy of multi-phase inverter-fed MATRIX motor using air-gap flux density

This paper describes a larger output torque production capability of the independent multi-phase inverter-fed electric motor drive for the automobile traction motor. The proposed method focuses on the radial and tangential component of flux density in the air-gap. The investigation reveals that the output torque depends on the relationship between the flux density of radial component and it of tangential component. In particularly, the large flux density with the small phase difference of them can increase the output torque. The FEA and experimental results show that the proposed method can produce larger output torque and can improve the motor efficiency compared with the conventional sinusoidal current excitation.