Nobuyuki Matsui

Design Studies on Hybrid Excitation Motor for Main Spindle Drive in Machine Tools

This paper presents a hybrid excitation motor for a main spindle drive in end- and face-milling tools which is operated with high speed 50,000 min-1. The proposed motor has not only a permanent magnet but also the field coil which makes field weakening and strengthening control possible with taking no notice of the magnet demagnetization. In addition, the sum of iron and copper losses of the motor at the end-milling operation is significantly reduced by the field weakening control. 3D-FEM based design studies on the proposed motor for the target application are demonstrated.

Brushless synchronous machines with wound-field excitation using SMC core designed for HEV drives

This paper presents drive performance possibilities of two types of brushless synchronous machine with wound-field excitation using SMC core for HEV applications. Both proposed machines have no brush or slip ring, but one uses a small amount of rare-earth magnet, it is called as hybrid excitation motor (HEM). The other has no magnet and employs only wound-field excitation. The structures and the basic working principles for both machines are overviewed. The design target is the motor with maximum power more than 123kW and maximum power density more than 3.5kW/kg. The performance analyses of the designed machines based on 3D-FEA show that both machines almost meet the target requirements. Some comparisons of the motor performances between both machines is provided. Finally, for HEM, some experimental results using a test machine are demonstrated.

Optimum Design Approach for a Two-Phase Switched Reluctance Compressor Drive

This paper presents an optimum design approach to a two-phase switched reluctance motor (SRM) drive. The proposed drive is designed for use as a compressor drive in a small refrigerator as an alternative to the existing brushless dc motor with rare-earth magnets. In the proposed approach, three genetic algorithm loops work to optimize the lamination design and to meet the requirements for the target application while simultaneously fine-tuning the control parameters. To achieve design optimization within a realistic timescale, the repeated calculation required to obtain fitness evaluation does not use finite-element analysis but instead consists of a dynamic simulator based on an analytical expression of magnetizing curves and a geometric flux-tube-based nonlinear magnetic analysis developed specifically for this class of motor. Design results show that the proposed approach can autonomously find a feasible design solution of an SRM drive for the target application from a huge search space. The experimental studies using a two-phase 8/6 prototype manufactured in accordance with the optimized design parameters show the validity of the proposed design approach.

Design of Saliency-Based Sensorless Drive IPM Motors for General Industrial Applications

This paper presents the design of saliency-based sensorless drive interior permanent magnet (IPM) motor for the general industrial application. To design accurately, considering magnetic saturation and cross-coupling effects are in FEA-based performance predictions. The reliability of the FE simulation is verified by experiment using a prototype. Then, the influence of the IPM rotor geometry on the feasibility region is examined. Consequently, the design guideline is established to obtain a suitable rotor geometry which can maximize the torque capability under the sensorless drive. Under the restricted specifications of dimensions and requirements, the 45Nm-5.5 kW 6-pole-9slot IPM motor is optimally designed. The validity of the proposed design is experimentally verified using the prototype.

A Novel Approach for Circuit-Field-Coupled Time Stepping Electromagnetic Analysis of Saturated Interior PM Motors

This paper presents a novel approach for circuit-field- coupled time-stepping electromagnetic analysis of a saturated interior permanent-magnet(IPM) synchronous motor. To predict the drive performance quickly, the proposed approach consists of a dynamic simulator based on a novel nonlinear model of the d-q- flux linkages of the IPM motor. The model can take into account not only the magnetic saturation but also the harmonics of inductance distributions and EMF waveforms. The validity of the model is verified from suitable simulation results of the instantaneous current and torque waveforms of the IPM motor. The proposed analysis has realized a dramatic reduction in the computation time compared to circuit-field-coupled time- stepping FEA, keeping analytical accuracy. A 10 kW-15,000 rpm prototype driven by PWM inverter was used for laboratory testing to verify the analysis. The experimental results showed quite reasonable agreement with the predicted instantaneous current.

Design studies on hybrid excitation motor for main spindle drive in machine tools

This paper presents a hybrid excitation motor for a main spindle drive in end- and face-milling tools, which is operated with a high speed of 50 000 r/min. The proposed motor has not only a permanent magnet but also the field coil which makes field-weakening and field-strengthening controls possible with taking no notice of the permanent magnet demagnetization. In addition, the sum of iron and copper losses of the motor at the end-milling operation is significantly reduced by the field-weakening control. The 3-D finite-element-method-based design studies on the proposed motor for the target application are demonstrated.

Sensorless-oriented design of IPM motors for general industrial applications

This paper deals with the sensorless-oriented design of interior permanent magnet (IPM) motor for the general industrial application. The finite element analysis is used to examine the influence of the IPM rotor geometry on the feasibility region for the sensorless rotor position detection. Consequently, the design guideline is established to obtain a suitable rotor geometry which can maximize the torque capability under the sensorless drive. Based on the guideline, the 45 Nm-5.5 kW 6-pole-9-slot IPM motor is optimally designed under the restricted specifications of dimensions and requirements. The validity of the proposed design is experimentally verified using the prototype.

A new flux-barrier design of torque ripple reduction in saliency-based sensorless drive IPM motors for general industrial applications

This paper proposes a new flux-barrier design to reduce the torque ripple of the concentrated-winding interior permanent magnet (IPM) motor under saliency-based sensorless drive. It is based on the combinations of the V-shape-magnet and the circular flux-barrier at the rotor-yoke in the center of the N-pole and S-pole. It is applied to 45Nm-5.5kW industrial drive IPM motor to fulfill the torque ripple requirement with a large operating region under the sensorless drive. The design result is validated by FEA, confirming the expected performance.

Optimization of Axial-Flux PM Machines for Improved Torque Density by Simple Non-Linear Magnetic Analysis

In this paper, a simple non-linear magnetic analysis- based optimum design of axial-flux permanent magnet (AFPM) machines is presented, which realizes the maximization of torque density while keeping motor volume. The proposed analysis consists of the geometric-flux-tube-based equivalent-magnetic-circuit model. The model includes saturable permeances taking into account the local magnetic saturation in the core. At first, the validity of the proposed analysis is examined for the various design free parameters. After verifying the accuracy of the torque computation of the proposed analysis through the comparisons with 3D-FEA, 8-pole 12-slot AFPM machine is optimally designed. Comparing to the traditional 3D-FEA, the design method proposed here has the same accuracy, while the computation time is as short as 1/700.

Design refinements and experimental test of hybrid excitation motor for main spindle drive in machine tools

This paper reports design refinements to make a trial manufacturing of hybrid excitation motor (HEM) for high speed spindle drive in machine tools. The proposed HEM is intentionally designed using 3D-FEA for the target application taking into account of practical design constraints. In accordance with the redesigned specifications, a test machine with 4-pole HEM is manufactured and tested. Some experimental results using test machine are demonstrated that the proposed machine achieves field strengthening and weakening control according to its working principle.