Soft coupling is a conceptual system in which two or more train sets on the same railway track can run like one long mechanically coupled train set, with very little space between the adjacent train sets. It is expected to open up possibilities for the realization of highly flexible and improved rail services. However, it is known to be very difficult for two separate train sets in motion to complete soft coupling, i.e., for the distance between these train sets to become zero. In the method we proposed in our previous papers, the time required for the completion may be infinite, because the train set that follows another must run faster when approaching the train set in front. This paper focuses on the method of completing soft coupling within finite time. We show that such a method can be proposed under the following set of preconditions: (1) infrastructure enabling the removal of the conservative safety concept of railway signalling called `brick wall' assumption, (2) simultaneous control of two train sets through a very secure wireless communications link, and (3) high-accuracy control of the deceleration of train sets.

The main purpose of this study is to improve efficiency of an induction motor. This paper describes a design approach to reduce both fundamental and harmonic losses using magnetic field analysis, wherein small air gap length and magnetic wedges are applied. It is clarified that reducing the air gap length and applying magnetic wedges decreases both fundamental and harmonic losses. The combination of the stray load loss and iron loss of the developed motor decreased by 19% compared with that of the conventional motor, and the total loss of the developed motor reduced by 15%.

This paper proposes a motor torque pulsation suppression method for electrolytic capacitor-less single-phase to three-phase power converter using dual inverter and open-end winding IPMSM. This system reduces the capacity of both the DC link capacitor and the additional capacitor by drastically pulsing the input voltage of a floating inverter. In the proposed system, the motor torque pulsation is suppressed by making the power supplied to the motor constant when single-phase ac power is pulsated. To realize the proposed method, this paper proposes a control method for the output voltage pulsation from the main inverter to the load motor with the floating inverter. The experimental results when using the open-end winding IPMSM as a load confirm that the motor torque pulsation is reduced by 95.5% as compared to the conventional system. Furthermore, the proposed control method achieves as input power factor of 95.4%.

This paper presents the design studies of a multi-layer interior permanent magnet synchronous motor (IPMSM) with a radially oriented arc-shaped hot-deformed magnet for automotive traction drives. Specifically, by using the IPMSM on a 2010 Prius as a benchmark, we designed an IPM rotor geometry that simultaneously achieves a 20% improvement in both the maximum power and constant output power line with high efficiency while maintaining maximum torque. A prototype of the designed three-layer IPMSM was manufactured and evaluated. The results of the tests conducted on the prototype are reported and discussed in this paper.

This paper presents a novel methodology of magnet temperature estimation using a magnet flux linkage observer for a Variable Leakage Flux Interior Permanent Magnet Synchronous M (VLF-IPMSM), whose parameters vary depending on load current conditions. The magnet temperature estimation algorithm consists of a Gopinath-Style flux observer, magnet flux linkage observer, and magnet temperature estimator based on the look-up table. The estimation accuracy is evaluated on d-q current plane by using both a behavior model of JMAG-RT and a control model of MATLAB Simulink. Then it is shown that the proposed methodology can be applied to a VLF-IPMSM for magnet temperature estimation.

High-precision positioning stages are an important apparatus in the semiconductor and flat panel industries. This paper reviews the model-based control techniques utilized in the feedback and feedforward control of the positioning control system. Multirate feedforward control with preactuation is an exact inversion of the discretized plant and it is effective for the reference tracking performance. Model-based feedback control using multiple sensors enhances the feedback bandwidth and improves the disturbance suppression performance. Additionally, this paper introduces new structures and control techniques achieving lightweight, high-thrust, and low disturbances.

As one of the motion control methods of electric vehicles (EVs), a driving force controller (DFC) with a slip ratio limiter has been proposed. The conventional controller has a slip ratio limiter for safety reasons, but it does not consider the lateral slip of the tire during cornering. To deal with this problem, this paper proposes a DFC with a variable slip ratio limiter based on brush model. The experimental results show that the proposed controller can work on both acceleration and deceleration cornering, by increasing the lateral force and lateral acceleration for smoother cornering.

The authors propose a system concept of direct power transfer from solar power generation as renewable power systems to self-battery charging-type electric movers. The proposed concept has a feature on usage of traction invertors and a mounted, small high-frequency transformer for fast battery charging. On the basis of this system concept, a useful application of solar power generation is expected.

In-wheel-motors (IWMs) are attracting considerable attention as drive-train for electric vehicles owing to their high motion performance, because of the absence of drive shafts compared with on-board motors. A large motor torque with limited mounting space and low-cost IWMs expect a geared drive-train, however, collisions of gear teeth cause vibration and deteriorate control performance and ride comfort. In order to suppress vibration, reduction-geared IWMs (RG-IWMs), which are IWMs with gears, are modeled as two-inertia system with deadzone model for backlash and joint torque control using both motor-side and load-side encoders for the two-inertia system is applied that our research group proposed previously. Simulations and experiments demonstrate that joint torque of RG-IWMs can be precisely controlled, vibration by collisions can be sufficiently suppressed, and the number of gear collision can be reduced during an acceleration situation. We expect that this research solves the critical problem of RG-IWMs, that is, vibration caused by gear collisions, and realizes the practical and commercial use of IWMs.

For practical realization of electric aircraft, we proposed a novel ultra-lightweight motor using a magnetic resonance coupling. In this paper, we clarified the variable speed characteristics of the proposed motor. Furthermore, we proposed a method for achieving excellent performance under conditions of constant capacitances. Our results confirmed that the proposed motor is capable of driving at variable speeds.

This paper presents the results of verification tests for the application of a 5th generation mobile communication system (5G) to an industrial robot control system, consisting of an industrial robot, a three-dimensional measurement sensor, and a robot controller. First, the configuration of the industrial robot control system to be used for testing was examined. Second, the 5G radio characteristics at two factories were measured. The radio interference to/from devices in operation in the factories and the human shield effect influencing the radio characteristics were also examined in these measurements. In factory automation, it is generally inevitable to spend a long time rearranging the components of the industrial robot control system. From the test results, it was confirmed that the time required could be greatly reduced by replacing wired communication lines with 5G capable systems.

This paper proposes a new mathematical model and simulator for synchronous reluctance motors, which generate torque ripples depending on the rotor position. The proposed model has the following advantages. (a) It has the generality that it is constructed in the general reference frame and can handle stator inductances in any form. (b) It comprises three self-consistent basic equations: circuit, torque-evolution, and energy-transmission equations. (d) It presents a new “inductance differential torque” that is directly related to the space-variable inductance, and can reproduce the torque ripples. The proposed simulator accurately reproduces the current, flux, torque, etc. specified by the model. Moreover, it adopts the most compact structure using the vector signals in the general reference frame. The model is validated in a rigorous analytical manner, and the usefulness of the simulator is demonstrated through simulations reproducing torque ripple depending on the rotor position.

This paper presents a new power control methodology for an inductive power transfer (IPT) system. The switching frequency of a class-D high-frequency inverter is adjusted in accordance with the variations in the resonant frequency due to the vertical and lateral displacements between the transmitting and receiving coils. Then, the output power is controlled byΔ-Σ signal transformation-based pulse density modulation (PDM). The feasibility of the proposed system is revealed through an experiment with a 400W-500kHz IPT prototype, in which the actual efficiency can be maintained over 80% for 20%-30% gap-length variations of the coils.

Our research focuses on the modeling of Virtual Power Plants in the future smart grid.