To achieve a wide range drive for an EV motor, the variable magnetic flux motor is developed. Using the control of the field magnetic flux strength, in addition to the conventional vector control, the limit of the maximum output and the maximum efficiency was considered. This paper describes the relevant considerations and the inspection results with the prototype motor.

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A boost converter is used to supply high voltage to the load in various industrial applications. Generally, boost converters have a large output filter capacitor to suppress the output voltage variation, and this leads to a considerable increase in the size of the system. In this paper, a load current feedforward control of boost converter is proposed. The proposed methods suppress voltage variation compared to feedback control and enable the reduction of output filter capacity. The simulation and experimental results show the effectiveness of the proposed methods.

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This paper proposes a configuration of a single-phase voltage source inverter that features power decoupling capability. Generally, the converter connected to a single-phase grid employs bulky DC link capacitors such as electrolytic capacitors in order to decouple the power ripple with twice the frequency of the power supply. The power ripple in the proposed circuit is compensated by an active buffer with small capacitors. In this paper, the fundamental operations of the proposed converter are confirmed by experimental results. From the experimental results, the output current total harmonic distortion (THD) is 3.51%, the ratio of the input current is 14.3% and the output power factor is over 99%. In addition, the volume of the proposed circuit is reduced by 61% when the carrier frequency is 64kHz compared to that with a carrier frequency of 16kHz. Finally, from an evaluation of the power density using Pareto front curves, the proposed circuit achieves high power density in comparison with the conventional circuit.

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EMS has the problem that if sufficiently controlled, the unintentional vibration occurs by disturbance. And it has been known the vibration changes with the value of the feedback gain. This study focuses on this phenomenon. The conventional method moved the targeted value of the gap and moved the mover. This method, however, does not fluctuate the target value of the gap and can produce variable vibration including frequency and the amplitude directly. The experimental result shows that gap gain can change the vibration frequency of the target.

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Railway operators usually do not consider the limit of the electrical energy supply in Japan. Allthough technologies have been developed for energy efficiency, the limit on the available electrical energy is not considered. However railway operators met the limit in summer 2011 after the earthquake off the Pacific coast of Tohoku. In this study, we develop an electrical energy allotment method for a large railway network. The method optimizes train operations to provide better railway service when the energy supply is limited. We also develop a search method to find the optimal operation from very large combinations of operation factors. These optimization and search methods are evaluated using the Tohoku earthquake scenario.

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Intelligent mobile robots are expected to reach target locations while avoiding obstacles. However, there are many obstacles in our living space. Therefore, it is not easy to develop wheeled or legged robots that can avoid obstacles in such environments. One solution is a blimp robot. It can go over obstacles easily and does not need much driving force. Our final goal is to develop a blimp robot that flies freely in a three-dimensional space. As a preliminary step, in this paper, we present the experimental results and discussion of airship control technology using an image processing system and wind disturbance observer.

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A controller design method is proposed for the communication disturbance observer, which improves the steady-state property by the modeling-error feedback. The proposed method stabilizes the system with a time-varying delay by designing a feedback gain in the observer system and output feedback controller using the Lyapunov-Krasovskii functional-based stability theorem. The controller is calculated by solving problems in the form of LMI by maximizing the allowable bound of the time delay and improving the performance of the system.

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This paper proposes a real-time modification method of position and force teaching information in a human-robot cooperative system. In this study, human motion is recorded using bilateral control to obtain position and force teaching information. When the recorded information is reproduced, a human operator can add an operation to modify the teaching information. Because of the ability to modify the teaching information, it is possible to create variations in the motion to accommodate environmental changes. On the other hand, without the modification by the operator, the original recorded motion is achieved. In the proposed method, the operator focuses on modifying the teaching information in order to realize the desired motion. The validity of the proposed method is confirmed by experimental results.

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In recent years, railway monitoring technologies that detect vehicles and pedestrians in railway environments such as platforms or railroad crossings have been developed. FMCW (frequency modulation continuous wave) radar for railway monitoring has been also reported. However, reflected signals having small power such as signals from pedestrians, are blocked by those from stationary objects such as the ground, because the signal components associated with stationary objects are diffused over the spectrum. Therefore, the authors have proposed stepped multiple frequency CPC (complementary phase code) radar, which can separate moving objects from stationary objects by estimating Doppler frequency. In this paper, we compare the basic performance of Stepped Multiple Frequency CPC with FMCW in a single target situation including many stationary objects at first. Next, the fundamental experiment results in railway environments, a platform and a railway crossing are shown. The results indicate that the developed radar could detect the target and obtain the velocities and ranges in such situations. In addition, experimental results with the radar fitted on the train are also shown.

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The switched reluctance motor(SRM) is considered a good candidate for a power source in harsh environments owing to its simple structure. However, it needs a rotor position sensor, which is generally unsuitable for those kinds of applications. In this paper, a novel method for detecting the rotor position without those sensors by introducing common mode signaling in the windings is presented. The signal is injected and detected in such a way that it is isolated from the current commutated for torque generation. The simulation results of the scheme will be shown to be practical. An experimental setup based on the signaling method successfully drove an SRM at rotational speeds over 100,000min^-1. Through the simulation and the experiment, the scheme has been proved to be practical and suitable for high rotational rate applications.

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We have developed a prototype of a 3-kV/200-A SiC hybrid module, equipped with Si IGBTs and SiC Schottky barrier diodes. We have achieved a reduction in the recovery loss and turn-on loss by using a SiC hybrid module and decreasing the turn-on time by lowering the gate resistance. Moreover, we estimated that the total energy loss of the converter and inverter using the developed SiC hybrid module was reduced to approximately 30%. Additionally, the inverter succeeded in driving an induction motor for a train.

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A two-layer three-phase contactless power transformer that has steady power-transfer characteristics, even at rotational misalignments, is proposed. The proposed transformer has three-phase coils arranged on each layer. The coils on the lower layer are arranged with a rotational shift by π with respect to those on the upper layers. Moreover, the coils on the lower layer are turned in the opposite direction to those on the upper layer. On the basis of the prototype of the proposed transformer, the equivalent model is derived. Using this model, the behavior of the proposed transformer is compared with that of the conventional three-phase transformer and is theoretically assessed. Experiments using the prototype confirm that the proposed transformer can output steady power and achieve good efficiency independent of the rotational misalignment. Moreover, the power transfer characteristics at the horizontal misalignments of the proposed transformer are measured and assessed.

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This paper proposes a method for robust control of a drive against parameter errors of permanent magnet synchronous motors (PMSMs). Direct torque control (DTC) of PMSM drive systems aims to realize maximum torque-per-ampere (MTPA) control by providing an optimal target magnetic flux. However, MTPA control by this approach cannot be realized owing to the following reasons. Command voltages and armature resistance are used in the estimation of the stator magnetic flux. Moreover, q-axis inductance and rotor magnetic flux are used in the calculation of the target magnetic flux. This paper proposes armature reaction flux control which can realize MTPA control in systems involving the above-mentioned error components. The proposed method compensates for these error components on the basis of the phase information of the current vector and the rotor flux vector in the maximum torque control (MTC) frame. By using the concept of the MTC frame, the proposed method is available to all PMSMs regardless of magnetic saliency. Finally, the effectiveness of the proposed method is confirmed experimentally.

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This paper investigates the magnetic saturation problem of self-sensing electromagnetic levitation system and presents a novel self-sensing scheme. The proposed approach employs a demodulation technique. By superimposing a high frequency voltage, the resulting electromagnet coil currents have ripples that can be used for gap sensing. This paper shows that the gap length is not uniquely estimated when using only the relation between the ripple, the control currents and the gap. The constraint conditions are to be determined to solve the problem. The proposed approach utilizes the dynamical motion model of the electromagnetic levitation system to uniquely identify the gap. Introducing the system behavior dynamics, the gap can be exactly estimated. To incorporate the system model with the gap sensing algorithm, a nonlinear filtering methodology is employed. The proposed estimator is demonstrated by the experiments. The results show that it is possible to address magnetic saturation with the proposed gap sensing scheme. The estimator has a good accuracy in a wider gap range compared to the conventional methods.

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Energy estimation of a train running simulator is useful for evaluating the effect of energy saving devices. The energy estimation requires the calculation of a speed profile representative of those based on various driving operation between two stations from a point of view of energy consumption. We developed a speed profile generator for a train running simulator, and it generates a speed profile for energy estimation. In contrast to a speed profile used for timetable planning, which shows the shortest possible running time between stations, the speed profile for energy estimation is calculated when the running time is given and it result in average energy consumption. The developed speed profile for energy estimation validates the good agreement of the energy consumption with the various commercial running data. Furthermore, we developed a method to extract a typical group of measured speed profiles from commercial running data. The speed profiles for energy estimation correspond to the typical group of measured speed profiles.

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The purpose of our study is to achieve dynamic model-based control of a nonlinear elastic-joint robot arm. We previously proposed a plug-in feedback scheme for vibration-suppression control of a serial two-link robot arm with joint elasticity due to a Harmonic-drive gear. The serial two-link arm simulates the 1st and 2nd joints of the SCARA-type robot or the 2nd and 3rd joints of the PUMA-type robot. In order to suppress the arm-tip vibration of both robot types, it is important to control the basic two-link arm. We proposed a torsion-angular-velocity feedback (TVFB) scheme, which can be plugged into existing joint servos (PI velocity controllers) using a nonlinear state-observer based on a physically parameterized dynamic model of the elastic-joint robot arm. The feedback gains of the observer are set to be identical to the PI gains tuned for the existing joint servos. Thus, the nonlinear observer, which estimates the torsion-angular velocity, is designless. This paper proposes a simple gain-scheduling scheme with a few hand-tuned state-feedback gains for improving the stability of the TVFB, taking the arm-posture and payload changes into consideration. We only have to manually tune a few state-feedback gains. Several experiments are conducted to demonstrate the vibration-suppression and fast-positioning capabilities of the improved TVFB using the elastic-joint robot arm.

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A pancake axial-air-gap-type synchronous motor is proposed, where the space harmonics power is effectively utilized for the field magnetization instead of the permanent magnets. The pancake axial-air-gap structure, i.e., a single stator with a double rotor configuration, greatly improves the mutual inductance, which is indispensable for the utilization of the space harmonics power for self-excitation. The advantages of the proposed motor are clarified in terms of the torque density with FEM based simulation results.

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This work proposes a sensorless control method for switched reluctance motor (SRM) using the ratio of PWM periods. The ratio of the PWM periods of one phase to that of another adjacent phase during exciting by each of hystresis PWM current control is used for the commutation of excitation. The effectiveness of the proposed method is verified via experiments.

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