Hiroki Hijikata

Design Methodology for Variable Leakage Flux IPM for Automobile Traction Drives

This paper presents a novel methodology for the variable leakage flux interior permanent-magnet (VLF-IPM) motor taking advantage of the variable leakage flux property in the rotor core controlled by the q-axis current, without any additional components. The fundamental phenomenon is explained with finite-element analysis results; then, the theoretical equations expressing the variable flux linkage controlled by the q-axis current have been conducted. The proof-of-principle model was designed, and the fundamental properties, such as torque-speed envelope and efficiency map, were evaluated. It was shown that the proposed motor can reduce energy consumption on duty-cycle driving.

Design and online winding reconfigurations method of MATRIX motor

This paper describes an online winding reconfiguration method to output the constant torque of MATRIX motor. MATRIX motor can change its winding configuration by multi-layer winding and switching devices. We have realized that the motor can change the motor characteristics, for example, the excitation of a quasi-distributed winding by using the concentrated winding. The winding switchover, however, is very risky attempt because an assertive switchover generates the surge voltage and following destruction of the switch devices. In this paper, we propose an on-line winding reconfigurations method which is focused on a zero cross point of the current waveform to prevent the surge voltage due to the switching. Furthermore, the output torque can be kept constant by changing the reference current which is calculated by the number of turn and the winding factor.

A basic study of MATRIX motor

This paper describes the characteristics of a new concept motor which can excite arbitrary waveforms. The motor is based on PMSM and the armature windings of the motor are consist of multi-layer concentrated windings connected by many semiconductor switches. The motor is named “Matrix motor” because the switches are turned on or off by the command of matrix. Various winding connection makes the arbitrary excitation waveforms, for example, the concentrated winding excitation, the distributed winding excitation, the multi harmonic excitation, and so on. The motor can realize a variable characteristic by changing its excitation. This paper shows the principle of the motor and its effectiveness is verified by the experimental results and the simulation results.

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.

Suppression control method for iron loss of MATRIX motor under flux weakening utilizing individual winding current control

An interior permanent magnet synchronous motor experiences large harmonic iron loss in the stator teeth caused by the harmonic magnetomotive forces. In particular, the eddy current loss remarkably increases at high rotational speeds under the flux weakening control. In this paper, a novel suppression control method for the stator iron loss is proposed by utilizing the individual winding current control. Although the proposed method requires multi-phase winding and multiple full-bridge inverters, the individual winding current control can observe and regulate the flux density in each tooth. This paper reveals that the proposed control method can achieve the extensive reduction of the total iron loss.

Design methodology for variable leakage flux IPM for automobile traction drives

This paper presents a novel methodology for the variable leakage flux IPM (VLF-IPM) motor taking advantage of variable leakage flux property in the rotor core controlled by q-axis current without any additional components. The fundamental phenomenon is explained with FEA results, then, the theoretical equations expressing variable flux linkage controlled by q-axis current have been conducted. The proof-of-principle model was designed and the fundamental properties, such as torque-speed envelop and efficiency map, were evaluated. It was shown that the proposed motor can expand output power in the high speed region, and decrease energy consumption.

Design technique and online winding reconfigurations method of MATRIX motor

This paper presents a design method and an online winding reconfigurations method of MATRIX motor. MATRIX motor can change its winding configuration by switching devices, it can change the motor characteristics, for example, a quasi-distributed winding excitation by using the concentrated winding is realized. This paper describes a design rule by a comparison between the conventional distributed winding and the quasi distributed winding. The winding switchover, however, is very risky attempt because an assertive switchover generates the surge voltage and following destruction of the switch devices. In this paper, we propose an online winding reconfigurations method which is focused on zero current period of the blushless dc drive. There is nothing to be any dangerous because this method is able to change the winding configuration by one phase during the zero current.

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.