Recently, many researches aiming at the realization of high performance and high precision control of induction motors have been reported, and instantaneous torque control of an induction motor can be regarded as one of the most important topics in this field. In previous works, the authors developed a new method to realize instantaneous torque control of an induction motor with a voltage-source inverter, and demonstrated both its numerical simulations and experimental results. Unfortunately, the mathematically complicated derivation of the control method made it difficult to understand intuitively, and hindered us from analyzing the detailed characteristics of motor speed changes.
In this paper, the authors propose a new method to realize instantaneous torque control of an induction motor, which differs from the concept of vector control. The proposed method is a two-degree-of-freedom control which considers the instantaneous torque command and secondary flux command as parameters. The analytical solution reported here is a particular solution of the differential state equation of an induction motor, and can be expressed as a simple explicit function of the instantaneous torque command, secondary flux command and motor speed. The authors show the validity of the proposed method through numerical simulations and experimental results. This paper aims the realization of high performance control of an induction motor. The authors propose a new method to realize instantaneous torque control without transient of torque with a voltage-source inverter.

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An AC line LC filter is usually installed in a power factor correction circuit with switching devices. But, the determining method of its resonant frequency and each parameter of a filter reactor and a filter capacitor has not clarified yet. This paper deals with the determining method of the LC filter in the cases of the discontinuous conduction mode (DCM) operation and the critical conduction mode (CRM) operation. The filter reactor and the filter capacitor can be evaluated by the total harmonic distortion factor, the phase lag of an input current and the ripple factor of a filer capacitor voltage. The optimum values of the LC filter are obtained by simulation.

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Recently, many methods of sensor-less control of PMSM (Permanent Magnet Synchronous Motor) are proposed. One of the methods is based on an induced voltage estimation using a disturbance observer. Though this method has a simple structure and it is convenient to realize the system, it has some disadvantages, for example, the estimation error occurs in a high speed operation area.
In this paper, we propose a new sensor-less control of a cylindrical type PMSM based on the estimation of the induced voltage. We combine the induced voltage with the flux linkage by integrating the induced voltage to estimate the motor angular speed.
As our proposed method does not need the induced voltage constant to estimate the motor speed, the estimation error is small even if the induced voltage constant is changed.
Finally, the effectiveness of the proposed method has been verified by experiments.

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This paper examined the robustness of former presented estimation method, that is made under very simple assumption of that, during short period of PWM control both electrical angle and electrical speed of AC servo-motor do not vary. In each PWM periods control input is known, currents is measurable, then position and speed as parameters can be solved.
Over 0.06 (p. u.) of speed command estimated position and speed had good accuracy, and smooth sensor-less control was achieved. Under 0.06 (p. u.) of speed command, 6-th harmonics in estimated position became harmful then correction using the Newton's Method is taken. Even these correction effort residues of correction error could not diminished. To reduce the effects of correction error, feed-forward voltage in control inputs are employed and gains of feedback was low downed.
On this estimation, machine parameters, armature resistance and reactance are supposed as constant. But they may be change according to temperature rise and magnetic saturation. Moreover they includes some errors. Even these problems under very short PWM interval changes of estimated EMFs are small enough then machine parameters disappear from estimate equation. Then this estimation method is robust from parameter changes.
This estimation method stands on estimation of back EMFs. Then it can not apply on zero speed. But experimental result shows a sensor-less start up under proposed estimation method without any other equipment is capable without any auxiliary equipment.

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A Switched Reluctance Motor has a doubly salient structure, both stator and rotor have saliency and it has an advantage in a harsh environments due to a simple and robust structure. There are two winding methods, the one is fully pitched winding and other is short pitched winding. A fully pitched winding of Switched Reluctance Motor has a number of different current-excitation patterns such as unipolar and bipolar. Its winding configuration results in more efficient use of the electric circuit, with each phase contributing to torque for more than half of the cycle of rotation. Therefore, for many machine configurations significantly greater torques are predicted for a given frame size. But output torques depend on the yoke thickness. This paper examines the output torques for the different yoke thickness and different current-excitation by the experimental and analytical results using the two dimensional finite element method. As a result, the torque performance of fully pitched winding SRM driven by the bipolar excitation is extremely affected with the yoke thickness.

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A method for calculating the single-step-response of 5-phase hybrid stepping motors is obtained. Effects of winding-connecting methods (1) star-bipolar SB, (2) pentagon PD and (3) new pentagon NP, on the single-step-response are investigated. By application of the above method, the continuous rotating characteristics are studied. It is clarified that the maximum slewing pulse rate of NP is higher than that of SB and PD connections, and that the variation of the rotor speed at high speed is large with SB and PD connections. Effects of the current wave form on the oscillation characteristics, and relation between the current wave form and the winding connections are investigated.

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This paper describes a new soft-switched PWM inverter with simple control. The control of the proposed inverter uses only PWM pattern for the output control The special control for ensuring the soft-switching operation is unnecessary. When the main switches are turned on, the zero-current-switching operation can be realized by the reactors in series. When the main switches are turned off, the zero-voltage-switching operation can be automatically realized by the cap acitors in parallel. The output currents of the proposed inverter have no distortion caused the blanking time for the prevention of the arm shorted fault at low output frequency because the load current can flow during the blanking time.
In this paper, the operation principle, the experimental results and the output characteristics of the proposed inverter will be described.

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Hydraulic control systems are used in most industries where heavy objects are manipulated or large forces are exerted on their surroundings. Recently, a positioning control of electrical hydraulic servo system is been applying a robust control theory which is strong for parameter variations or nonlinear elements, instead of as usual a PID control used in widely industries. The purpose of this research is to evaluate several robust control performances and investigate their aptitude for the oil hydraulic system.
In the first paper, we proposed several evaluation methods and standard of designs considering a characteristic of the electrical hydraulic system, and decided system parameters for three kinds of robust control systems which are a Disturbance Observer, a Sliding Mode Control (SMC) and a H_∞ control, according to the several standard of designs. Next, we applied them to the actual electrical hydraulic servo system, and evaluated the difference of the control performance from the point of view of a robustness for load variations as the parameter variations, a characteristic of disturbance cancellation and a control input.
In this paper, the control performance of the robust control systems is evaluated, when they are applied to the positioning control of the electrical hydraulic servo system included of the several parameter variations or the nonlinear elements, which are not only the load variations, but also a oil temperature variations, a pressure variations, and a desired value variations. As a result, all of them have shown good robustness in the load variations, the oil temperature variations, the pressure variations. but the H_∞ control has shown better performance in the desired value variations than other control systems. Further, the SMC has shown good performance in the control input, because it has been smaller than other control systems in the control input.

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A Synchronous reluctance motor has many advantages because it has no permanent magnet, such as low back emf in a high speed operation, keeping performance in a high temperature environment and so on. Therefore, many rotor constructions are studied and developed. The rotor with multi-flux barrier structure has the merit of its easy construction and high performances.
The linear synchronous reluctance motor have been developed. It is necessary to improve the performance by the mover design for industrial use, because of its low power factor.
In this paper, we propose a novel configuration of mover for linear synchronous reluctance motor, and examine the static characteristics of linear synchronous reluctance motor with reluctance equalization design by using finite element method. From analytical results, it is cleared that the static characteristics of the linear synchronous reluctance motor is greatly improved by the reluctance equalization design at the iron layer in the mover.

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To improve the quality of products in a steel making process, the realization of a non-contacting conveyance of a steel plate has been expected. To make the total system simple, we proposed a combined lift and propulsion system by transverse flux linear induction motors. By feeding the DC biased AC to the transverse flux linear induction motor, it is possible to realize an efficient combined lift and propulsion system with a simple structure. After showing the peculiarities of the system, conveyance experiments of a steel plate are carried out. In these experiments, the equivalent mass estimation method in which the levitation mass is estimated from the gap error is applied and the effect of the method is also shown.

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In the Yamanashi Maglev Test Line, the location of the train is detected with the inductive radio system. The inductive radio system is very reliable and accurate. However using the inductive radio system, we have to lay the cross inductive cable along the guideway accurately and set up the detecting system of train's location in each power conversion station. Therefore the cost of construction and maintenance is very expensive. Moreover, from the redundancy point of view, it is necessary to examine the other method of detecting train's location, in case of inductive radio system down.
We have already proposed a new train's location detecting system using the phase of Electromotive Force (EMF). In this system, the reduced-order state observer estimates the phase of EMF. Therefore the inductive radio system is not required. We have reported the configuration and the basic characteristics of the EMF observer. In this paper, we report the experimental results of running test at the speed of 300km/h_??_0km/h in the Yamanashi Maglev Test Line. We confirm the performance of velocity and current control with EMF.

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We have proposed the “surface induction motor” which is an induction type of two-dimensional motion motor with a circular shaped primary core. The primary member is composed of a toroidal core and the armature winding of separated coils for each current supply. The secondary member is a conducting plate with a back iron plate. As it can make a flexible traveling field in any region on the circle, the motor enables an arbitrary directional planar drive including a rotation. We have reported the characteristics at standstill so far. This paper presents the characteristics at movement. The slip and speed characteristics for the rotating motion and the linear motion respectively are cleared experimentally and theoretically. For the analysis, the two-dimensional electromagnetic analytical method is used, in which the direction of circumference of the toroidal core is transformed to the direction of x-axis. In linear motion, the traveling fields in both sides for the moving direction are made along the semicircle. To study theoretically about the slip characteristics of linear movement for the speed of traveling field, we propose the polygon model with linear motors arranged along the semicircle. The validity of the analysis is proved by experimental results. It is cleared that the equivalent synchronous speed in the moving direction for the traveling field speed is 0.884, By comparing with the two linear motors configuration for two-dimensional drive, the advantage of surface induction motor is shown.

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This paper newly presents a unified analysis of a set of two filters that are accompanied with two vector rotaters. The filters can make distinction between positive and negative frequencies of three-phase signals and can allow us to process the signals based on frequency polarity. Such attractive feature can never be obtained from standard filters. The presented analysis is unified and plain, and its result is general and simple so that it can be applied to a variety of filtering applications.

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In recent years, the harmonics and EMI noise sent out from an electric power conversion system are getting a great deal of attention in electromagnetic environment problems. So, the considerations for mentioned above have been getting important. Therefore, there is need to do a detail frequency analysis such as transient phenomena at the switching. So, we have proposed the analytic technique using Wavelet-transformer which is possible to catch a phenomenon from the both sides of the time and the frequency. In this paper, we performed the analysis using Wavelet-transformer against the actual measured date at the switching interval. Then, based on obtained result, we describe the high validity of Wavelet-transformer and the application to the power electronics field.

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