Junichi Tsuchiya

Mover structure and thrust characteristic of moving-magnet-type surface motor

A few types of surface motors (SFMs) having the ability to perform surface motion have been proposed. However, most SFMs are limited in movement because the movers used depend on electrical wires to supply the operating current. The authors have proposed a new type of SFM that does not require wires to be connected to the mover. The most advantageous feature of this new type of the SFM is that the mover can perform rotation in addition to linear motion on a plane surface. This SFM might be useful for the application in a sealed space, because the mover and the stator are completely separate. In this paper, the number of magnetic poles in the movers and their arrangement are examined. The thrust characteristic of each magnetic pole arrangement is measured experimentally. As a result, the optimum magnetic pole arrangement of the mover is obtained.

Stator design of revolvable surface motor

Most surface motors (SFMs) which move on an x-y plane are limited by the moving region because their movers are connected with the wire. The new type surface motor proposed by the authors has no such restriction because the mover is free from the wire connection. The mover can rotate by itself in addition to the liner motion on an x-y plane. This paper presents the principle of operation and improvement of the stator shapes for the increase in thrust of the surface motor. As a result, the SFMs thrust characteristics have been improved about 25%. Furthermore, the optimum length of the air gap between the mover and the stator is examined.

Improved operating characteristics of linear pulse motor using resonant current

The linear pulse motor (LPM) requires strong thrust force and smooth movement with suppression of its pulsation and pulling-out. To respond to these requirements, several methods have been reported. But there are some defects such as large power loss, complicated additional circuits, deterioration of thrust force characteristics at high operating speed and so on. This paper describes the new control circuit improving these defects, in which the variable capacitor or switched variable capacitor circuit is connected with a motor winding in series. This capacitor is controlled to maintain the resonant condition that is achieved by the capacitor and the inductance of the motor windings, and this circuit makes the exciting current waveform sinusoidal. It is confirmed that the resonant current of the sinusoidal waveform causes the smooth movement and improves the thrust force characteristics over the wide range of pulse rates.<<ETX>>

A simple speed control method for small induction motors base on phase difference

Some form of simple control is needed for small induction motors. This paper proposes a simple speed control method for small induction motors using a simple calculation without the need for a speed sensor. In this method, the load torque is estimated from the detected power factor of the induction motor and the speed of the induction motor is compensated for by a frequency-boost technique. The boost frequency is selected from a data table measured beforehand. Satisfactory experimental results are obtained with 90 W induction motors.

Speed sensorless field-oriented control based on phase difference

Speed sensorless field-oriented control strategies that estimate rotor speed are being researched and many methods have been presented. However, in general, complex calculations are necessary to estimate the rotor speed. In this paper, an original sensorless field-oriented control method for an induction motor using easy and simple speed estimation is presented. In the proposed method, the motor speed is estimated by measuring the command frequency and the phase difference between the stator current vector and the stator voltage vector. By comparing the measured values with a table of data measured beforehand, the rotor speed can be estimated satisfactorily through simple calculations. In this paper, the principle and method of speed estimation and control set-up are described, as well as the results of an experiment that verified the effectiveness of the proposed method.

Regeneration characteristics of speed sensorless control method based on phase difference

A simple speed control method is needed for small induction motors. Previously, the authors have proposed a simple speed sensorless control method for small induction motors. In this method, the load torque is estimated from the phase difference between the stator current and the stator voltage, and the drive frequency is calculated from the estimated torque. As a result the average speed of the induction motor remains constant. This paper presents the principle of this method and the experimental results including the regenerative regions with a 400 W induction motor.

Instantaneous value control using a synchronous-integrating filter for PWM AC voltage regulator

Instantaneous value control using a synchronous-integrating filter and a digital signal processor (DSP) for the PWM (pulse-width modulation) AC voltage regulator is presented. The proposed system has a quick response, thus achieving the performance of the high-speed AC chopper using power MOSFETs. A novel type of filter, a synchronous-integrating filter, completely eliminates the ripples in the output voltage caused by PWM chopping operation. The sampling values of the filter output are considered to be the instantaneous values of the fundamental component included in the output voltage. A high-speed DSP instantaneously computes the pulse width at each chopping cycle. The dead time is to be considered in the control algorithm. Experimental results show that the proposed system has a quick transient response, within a few hundred microseconds. Moreover, it is possible to reduce the low-order harmonic distortion.<<ETX>>

Firefly algorithm using cluster information for superior solution set search

We analyzed the search characteristics of Firefly Algorithm (FA), which has a fundamental nature of a Superior Solution Set Search Problem, previously defined in our previous study for single-objective optimization problems. In this study, we proposed a new FA method based on the former problem. This method, which employs cluster information by K-means clustering, is tested for performance by fundamental numerical experiments.

Adaptive Cuckoo search based on ranking of search point

Recently, the development of high-performance metaheuristics has become an important subject. In this study, an adaptive Cuckoo Search based on ranking of search point is proposed. This study aims to improve the performance of Cuckoo Search by adjusting the parameter β to allow search points with good evaluation value to search nearby and those with poor evaluation value to search far away. Finally, the performance of the proposed method is evaluated by numerical experiments.

Magnetic pole shape optimization for motor using integrated optimization with constraints

While we have developed Integrated Optimization which consists of optimization method, modeling method and simulation technology in order to solve practical optimization problems, the high performance of Integrated Optimization has been confirmed through simulations using typical benchmark problems. In this paper, Integrated Optimization with constraints is newly developed and applied to optimal design of magnetic pole shape of a surface motor. Furthermore, we design a magnetic pole shape of a surface motor by using Integrated Optimization with constraints in order to aim at a practical design, and compare the pole shape designed by the developed approach with that by an expert.