The utility grid voltage of commercial AC power source in Japan and USA is 100V, but in other Asian and European countries, it is 220V. In recent years, in Japan 200V outputted single-phase three-wire system begins to be used for high power applications. In 100V utility AC power applications and systems, an active voltage clamped quasi-resonant inverter circuit topology sing IGBTs has been effectively used so far for the consumer microwave oven. In this paper, presented is a half bridge type voltage-clamped asymmetrical soft switching PWM high-frequency inverter type AC-DC converter using IGBTs which is designed for consumer magnetron drive used as the consumer microwave oven in 200V utility AC power system. The zero voltage soft switching inverter treated here can use the same power rated switching semiconductor devices and three-winding high frequency transformer as those of the active voltage clamped quasi-resonant inverter using the IGBTs that has already been used for 100V utility AC power source. The operating performances of the voltage source single ended push pull (SEPP) type soft switching PWM inverter are evaluated and discussed for 100V and 200V common use consumer microwave oven. The harmonic line current components in the utility AC power side of the AC-DC power converter with ZVS-PWM SEPP inverter are reduced and improved on the basis of sine wave like pulse frequency modulation and sine wave like pulse width modulation for the utility AC voltage source.

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This paper deals the digital optimal current control scheme to improve MRI (Magnetic Resonant Imaging) Gradient-Magnetic Coil (GC) current control implementation. The GC current needs high precision control specifications so as to take clear images with MRI. The novel MRI-GC current control amplifier has the high-frequency PWM chopper circuit with a multi-parallel input structure. The GC current control circuit can prevent the current ripple amplitude and realize high precision GC current controls, but the control system is hard to design because the GC current control circuit has the multi-input and multi-output structure and required high precision control abilities. Therefore, the digital optimal control scheme has tried to apply for the GC current control. The optimal controller is skillful at the design of multi-input and multi-output systems. The novel controller will actualize the high precision GC current controllability because Error System newly includes the GC current error parameter so as to decide the multi-inputs. In this paper, we discuss the novel controller with computer simulations that it can expect the high precision GC current control to improve the image quality of MRI systems.

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This paper presents a simple non-linear magnetic analysis-based optimum design of a multi-pole permanent magnet machine as an assistant design tool of 3D-FEM. The proposed analysis is based on the equivalent magnetic circuit and the air gap permeance model between the stator and rotor teeth of the motor, taking into account the local magnetic saturation in the pointed end of teeth. The availability of the proposed analysis is verified by comparing with 3D-FEM analysis from the standpoints of the torque calculation accuracy for the variations of design free parameter and the computation time. After verification, the proposed analysis-based optimum design of the dimensions of permanent magnet is examined, by which the minimization of magnet volume is realized while keeping torque/current ratio at the specified value.

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This paper describes offset optimization for the fluctuations of traffic flow using a genetic algorithm (GA). An Offset which is the target of signal control parameters for this study is difficult to optimize because of its variety of combinations. Traffic signal optimization using GAs has been investigated in previous studies. Most of them however, focused on signal control without considering the fluctuations of traffic flow. In a practical scene, the rate of flow changes as time passes, so that offset-optimization considering these fluctuations of flow is required. As a case study, an urban traffic route in a city of the Chubu region in Japan, with twenty-one signalized intersections, was tested. To perform offset-optimization by a GA, offset values were represented in a chromosome having the same number of genes as the signals. Two different schemes are introduced into the GA-based program and evaluated in terms of average travel time. The results show that the offset optimization schemes used in this study were valuable for efficient signal control.

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Stepping motors are generally used as a positioning servo in the OA (Office Automation) and FA (Factory Automation) system because the construction cost is very low and the construction of system is very easy. Since they are generally driven by an open loop controller, the response of stepping motors is oscillatory and it is possible to be out of drive. Therefore they are driven by a closed loop controller in the special system, which requires the high reliability and stability. The lead angle control is used as a closed loop controller of stepping motors because an applied voltage amplitude is not able to be controlled. However a closed loop control of stepping motors is hardly used at present. This paper presents the lead angle control based on the vector control in the constant voltage drive range for 2 phases HB type stepping motors. In the constant voltage range, since the HB type stepping motor is modeled as a surface permanent magnet motor, the motor torque is controlled by the q-axis current. The d-axis current is calculated by the voltage limit condition because of the constant voltage amplitude operation. The control performances are examined by the simulations and experimental results.

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In this paper, we describe a model reference type sliding mode controller for a two-mass speed control system. The two-mass system consists of a dc motor, a load inertia, and an elastic shaft which connects between them. To design the conventional sliding mode controller for the two-mass system, the nominal parameters of the system are required. Although the nominal parameters of the motor side such as the dc power amplifier gain K, the motor inertia J₁ and the torque constant K_t are easy to know, the load side parameters such as the load inertia J₂ and the stiffness of the shaft K_e are unknown in advance and can not be used in the design. Therefore, the design method without using the load information is expected. In the paper, new design scheme of the sliding mode controller, in which a reference model and an adaptive mechanism are introduced, is proposed. Some experimental responses of the system under the proposed sliding mode control are measured. These result the compatibility of simplification of the design procedure and robustness for the friction, the modeling error and the disturbance.

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This paper dicusses the problem of parking assistance system development. Firstly, we propose the driver assistance systems general architecture based on path planning and human interface modules. A path generation method based on parking possibility area is developed for the parking assistance systems. The human interface designed for the parking assistance systems is then described. A prototype of the parking assistance systems based on the proposed architecture and approaches have been constructed. Proposed algorithms and implementation solutions in the prototype construction are described. The lane and row parking experimental results obtained with the prototype systems are also shown.

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In magnetic disk drives, several controllers switch from one to another to perform one servo action. These mode switching controllers provide fast access and accurate positioning. The requirement of faster seeking in magnetic disk drives propagates residual vibration during settling due to the mechanical resonance of the positioning system. We have developed a settling control mode designed to reduce the residual vibration caused by primary mechanical resonance. Our method consists of a closed loop design to stabilize the primary resonance by tuning the phase of the open loop transfer function without a notch filter and a design of controller initial values at settling start point. The method is more effective in reducing vibration compared to the conventional method using a notch filter because the transfer functions from the initial state variables of the primary resonance to the position of the actuator are significantly damped at the frequency of the primary resonance. Simulation and experimental results on transient characteristics in track seek show that the method provide fast and vibration-free settling on the target track.

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We propose a desired-value filter composed of time-difference comparison between desired value and feedback variable of a control system. In this filter, the function of the time-difference comparison is introduced in the usual error detector in order to make a moderate comparison, in results, to accomplish a superior response towards the desired value as a two-degrees-of-freedom control.

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The dependence of the multigrid-finite element method solving three dimensional magnetostatic fields on the quality of the finite element mesh is reported. It is shown that the convergence of the multigrid method is strongly influenced by the mesh quality. Moreover, the multigrid method with ICCG-smoother is shown to be more robust against mesh distortion than that with Gauss-Seidel and SOR smoothers.

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This paper proposes a new concept for a contactless electrical energy transmission system for an elevator and an automated guided vehicle. The system has rechargeable batteries on the car and electrical energy is supplied at a specific place. When electric power is supplied to the car, it runs automatically and approaches the battery charger. Therefore, a comparatively large gap is needed between the primary transformer at the battery charger and the secondary transformer on the car in order to prevent damage which would be caused by a collision. In this case, a drop of the transformer coupling rate due to the large gap must be prevented. In conventional contactless electrical energy transmission technology, since electric power is received by a pick-up coil from a power line, a large-sized transformer is required. And when the distance over which the car runs is long, the copper loss of the line also increases. The developed system adopts a high frequency inverter using a soft switching method to miniaturize the transformer. The system has a coupling rate of 0.88 for a transformer gap length of 10mm and can operate at 91% efficiency.

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This paper proposes a novel induction motor drive system using a three-phase V-connection ac chopper that consists of two single-phase ac choppers. There are three new topics proposed in this paper. Firstly, this paper proves that the three-phase V-connection ac chopper can be operated properly only if the input and the output voltages are in synchronism . Secondly, a novel commutation method for ac chopper isproposed. The proposed commutation method combines the load current commutation and the input voltage commutation. Therefore, by applying the proposed commutation method, voltage and current surge around zero crossing of the input voltage and the load current do not occur. Thirdly, a novel high effciency control method for induction motor is proposed. The proposed control method does not require d-axis and q-axis current components, but uses only the magnitude ofthe primary current. The whole control system has a very simple structure. These new topics are confirmed by experimental results on a 750W general-purpose induction motor.

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In this paper, a position control of a linear slider with twin linear drives is considered. Recently, for the high-speed response, several linear motors are used for the linear slider system . In such a linear slider, if the linear drives are controlled individually, these position responses possibly vibrate by interaction of output of the motors. For the method to control this vibration, this paper shows the dynamic model of the linear slider system which consists of the decoupled two motion systems by coordinate transformation, and proposes a feedback controller which is designed for these two decoupled systems. Effectiveness of the proposed method is confirmed by experiments.

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This paper points out that dc magnetic-flux deviation may occur in a doubly-fed flywheel genarator with primary-current feedback control. The flux deviation discussed in this paper, which is different from the common flux deviation caused by a dc output voltage of a PWM converter, is induced by an ac output voltage of the PWM inverter operated at the angular frequency of the rotor. It may be impossible to detect such a dc flux from the primary current and/or voltage, because the dc flux induces no voltage on the primary windings. This paper reveals that the primary-current control induces a dc flux in the primary windingsand prevents the dc flux from decaying. A new control method for suppressing the dc flux deviation, which is based on calculating the exciting current from the primary and secondary currents, is proposed. Experimental results verify the viability of the control method proposed in this paper.

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Novel electric ballast for HID lamps which can not only supply the stable discharge current but also generate high voltage for initiate its restarting instantaneously is presented. On the restarting process of the HID lamps, the discharging starts at a glow-discharge and changes to stable arc-discharge. However, it is necessary to inject adequate voltage onto the HID lamp depending upon the previous discharging condition. The immittance-conversion elements, which are composed of a coaxial cables, are applied in order to realize above mentioned requirements. Furthermore, multi pulse injection method is presented for quick restarting of the HID lamps. The effectiveness of the proposed circuit is verified through the experimental results on the experimental setup for 75W HID lamp.

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In most power electronic applications, the AC power input provided by the electric utility needs to be first converted to a DC voltage. Such conversion is usually accomplished by a diode rectifier due to its circuit simplicity and low cost. However, since diode rectifiers have some intrinsic problems such as low power factor and high harmonic distortion, a wide use of such rectifiers may cause noises, malfunction and heat damage in both electrical power systems and electrical machinery systems. This paper proposes a soft switched three-phase single switch boost-type rectifier. The proposed circuit can perform zero-voltage-switching (ZVS) without using any current and voltage sensors. For this circuit, both simulation and experiments have been performed. The results not only confirmed the zero-voltage-switching (ZVS) but also indicated that, compared to the conventional hard-switched rectifier, the proposed circuit can improve the efficiency as much as 1.7 to 4.7pt while keeping the same high power factor and small harmonic distortion in their AC input.

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In this letter, system identification problem under imperfect information is considered. As an example, system identification of a mobile robot by using image information is treated. To cope with the imperfect measurement data, a data processing method by support vector machine is proposed.

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