This paper proposes a new scheme for speed-sensorless control of an IM for general purpose drive applications. The scheme combines both field oriented and V/f techniques. The V/f technique used here is based on the instantaneous stator-flux space vector control method. The PWM principle made it possible to maitain the amplitude of the stator-flux space vector constant while commanding its rotation speed such as to generate the desired torque. The principle of speed and torque control is based on the field orientation of a d-q rotating frame. In such a case, an equivalence between the current control and the torque control is achieved. The control system was tested at different operating conditions and the experimental results have shown good motor characteristics during transients as well as in steady states.

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For a linear induction motor (LIM), the constants of each phase are different due to the motor structure. This can cause the thrust pulsation of the LIM. This paper shows a vector control method of a LIM taking into consideration its asymmetrical constants and its characteristics. The thrust pulsation is suppressed by this control method.
The vector control method with the asymmetrical constants consists of the slip angular frequency control, the time-invariant control and the decoupling control. The speed control system is based on the vector control. The control characteristics of the new system, in the four quadrant operation, are superior to those of the conventional vector control system performed by the average values of the asymmetrical constants.

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In this paper, we describe a high performance VTR motor servo system based on modern control theory, which eliminates wow and flutter and improves control capability. Specifically, we developed a new method of motor control, composed of an acceleration controller and a sensor noise reduction system using disturbance and velocity observers. The results of this development were a reduction in wow-flutter by nearly 20dB measured at the capstun motor and 10 dB measured at the drum motor. In addition, high band disturbance estimation using the velocity observer's noise reduction system allowed a design of robust system using disturbance compensation.

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The history of electric vehicle is very long. Many kind of electric vehicles were developed and used practically. In Japan, from 1971 to 1976 so called big project for EV sponsored by the Ministry of International Trade and Industry developed epoch-making EVs for that age. However, former electric motor vehicles were not comparable with gasoline-driven vehicles as regards performance and cost, and infrastructure like battery chargers were not provided. These are the reason why electric vehicles never came into widespread use. Recently in the world, many projects are developing electric vehicles because environment on earth are recognized as the most important problem.
In order to change the conventional image of electric vehicles, we have, in accordance with new concepts, undertaken the development of a high-performance electric motor vehicle. It was named as the IZA. The performance of IZA are as follows, maximum speed is 176km/h, range per one charge is 548km for a constant speed of 40km/h, and the acceleration from 0 to 400m is 18 second. It's performance and characteristics are comparable with those of gasoline-driven vehicles. Characteristics of this vehicle are:
(1) Four (4) motors are employed, and they drive wheels directly without mechanical gear.
(2) Motors are synchronous motors with permanent magnets which are made by samariumcobalt. The motors are placed inside of wheels.
(3) Controlled current inverters are employed for each motors.
(4) Type of batteries are nickel cadmium, they are divided to two parts and placed in front and rear of the vehicle respectively.
This paper presents the drive system of the electric vehicle.

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This paper relates to a high performance speed control method of two inertia resonant system. The two inertia resonant system is made up of a motor, a load machine and an axis jointing them each other. The control problem of this system is to perform the speed control of the load machine satisfactorily.
This paper proposes the control method of the two inertia resonant system with the speed controller forming the two degrees of freedom control system designed to be based on the coprime factorization description of the system. The speed controller is made up of a stabilizing dynamic compensator and a reference signal response dynamic compensator. The former takes the function of the stabilization, the disturbance suppression, and the strongly stabilization of the system. The latter takes the function of the reference signal response. This paper shows a design method of the two dynamic compensators mentioned above, and a design example of the dynamic compensators, simulation results and experiment results of the test machine.

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Three-phase current sensors are required in power-line distribution systems to monitor currents and protect systems from possible failures. Zero-phase current sensors are also required to detect leakage currents between power lines and the earth, thus preventing accidents like a fire. This paper describes new three-phase and zero-phase current sensors which are based on a zero method. The sensors consist of Hall ICs, coils, and electronic circuits; no magnetic cores are used. The three-phase current sensor provides measurements of currents from 0.8 A to 720 A with excellent accuracy, while the zero-phase current sensor provides measurements from 90 mA to 20 A. The output signal levels are suitable for microprocessor-based metering and control systems. The sensors are relatively small and light-weighted compared to a conventional current transformer (CT). Moreover they withstand excess curents and do not yield burning or deterioration. They do not require expensive components so they have an advantage in cost compared to an optical-fiber current transformer.

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The nonlinear state feedback control of field voltage to improve the pull-in performance of the synchronous motors is proposed in this paper. This nonlinear control is valid in all operating area. The machine constants are equivalently changed by the nonlinear control to improve the pull-in performance. Since the system is represented with a nonlinear system, the stability of this system is judged by Lyapunov's direct method. The optimal feedback gains of the controller are determined by using Lyapunov function. The validity and usefulness of proposed method are investigated by numerical calculations and experiments.

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We have studied a thin actuator for application in an ultra thin optical disk drive. First, a simple calculaton method of thrust using a permeance method is described. Then using this method, the thrust is estimated for a permanent magnet type linear pulse motor (PM type LPM) and a voice coil motor (VCM) which is generally applied to the optical disk drive.
This estimation shows that acceleration of the PM type LPM is 1.6 times larger than that of the VCM when the actuator thickness is smaller than 15mm. We fabricated a 6-mm-thisk PM type LPM having a thrust constant of 0.78 N/A and a maximum thrust of 0.5 N.

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The important design factor of superconducting generator is the estimation of the electromagnetic forces at the rotor dampers on sudden three-phase short-circuit. In this paper, the armature current and electromagnetic forces on sudden three-phase short-circuit are directly simulated by two-dimensional transient analysis, considering the following complex terms.
(1) Induced current by the speed electromotive force caused by the rotor rotation. (2) The connection of three-phase windings. (3) The resistance and reactance at the armature coil-end.
The speed electromotive force is considered by using the combination method, which is FEM combined with BEM at the air gap. The connection of the armature winding and the effect of the armature coil-end are considered by using the analysis combined with the external circuit equations. Moreover, the effect of the Roebel-transposition of the armature winding is approximately considered.
By the authors, analysis, the electromagnetic forces at the rotor dampers can be calculated with a high accuracy.

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Concerned as the linear induction motor(LIM) there appear two kinds of end effect, one is in the running direction and the other in the transversal one. In this paper, we investigate the latter especially. When the reaction rail is displaced in the transverse direction, it causes both the reduction of thrust and the normal force. The purpose of this paper is to investigate such a structure of the reaction rail as to minimize the above phenomena.
In this paper, we analyze 3-D electromagnetic fields of a concrete LIM by using the finite element method(FEM). Especially we consider the cases of both extending the reaction rail and reinforcing the end ring of secondary conductor.
To analyze the transverse end effect exactly, we also devise the expression of the diamond coil.
Some numerical results obtained by this approach are compared with measured ones. The calculated values well agree with the experimental data.

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This paper presents a flow control of molten tin surface sloping by a Single-sided Linear Induction Motor (SLIM) in a float process that is a typical forming method of flat glass. Flow pattern in the molten tin bath is quite important to keep the good quality of float glass.
The following results are obtained:
(1) It is verified in experiments that the SLIM can maintain a whole surface of molten tin sloping with molybdenum-made bus-bars.
(2) The 80 millimeter-wide bus-bars for the SLIM with pole pitch of 156 millimeters is enough to get the desirable flow direction of molten tin adjacent to the bus-bars.
(3) It is theoretically discussed that the distribution of the secondary current density in molten tin can be controlled with bus-bar conditions.

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The authors have been investigating the basic technologies to an artificial heart driving using a linear pulse motor (LPM). This type of artificial heart is able to promise the possibility of downsizing.
This paper describes the results of research on duration of the LPM which designed for use in a total artificial heart, the duration was evaluated by the MTTF ( Mean Time To Failure ). The calculated value of MTTF of the LPM was obtained to be 3200 hours, 137 days. The main reason of this short duration was caused by large failure rate of the linear bearings.
Actual duration of the LPM was confirmed under accelerated-life testing. Using the acceleration coefficient, the measured value of the duration was 2800 hours, 117 days, the duration was also decided destruction of the linear bearings. Calculated value of the duration agreed well with the measured value, but these values were at least one order smaller than the ideal total artificial heart. This paper also has proposed the method to improve the duration of the LPM for the total artificial heart.

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