Electromagnetic suspension (EMS) has been widely used in many industrial fields because of various advantages in practical use. The U-type magnets are often used to generate the levitation force in the EMS system. This conventional electromagnet, however, can only control one degree-offreedom. It cannot construct a levitation system solely by itself. A 4-pole type yoke hybrid electromagnet is proposed instead of the usual U-type magnet and its magnetic levitation control is studied in this paper. The basic structure and characteristics of the proposed magnet are described first. Next the control system is designed. Luenberger observer, only using gap sensors, is applied to realize zero-power control. The semi-zero-power control with a disturbance observer is proposed to improve the performance, as well as the robustness, of the control system. Finally, the simulation results and corresponding experiments have been presented.
The switched reluctance motor (SRM) exhibits desirable features including simple construction, high reliability and low cost. However the SRM has not been put into practical applications widely because of its large torque ripple, acoustic noise and low power factor. Furthermore, the quantitative analysis and optimum design of the SRM have not been clarified thoroughly. In this paper, the authors propose one method for calculating the operating characteristics of the SRM based on the general-purpose circuit simulation program “SPICE”. In the method, we use a SPICE model of the nonlinear reluctance based on the magnetization curves calculated by FEM in order to consider the nonlinear magnetization characteristics. The calculated results obtained in the trial 8/6 SRM show good agreement with the experimental ones. The method is useful for optimum design of the SRM.
The use of PWM-inverter with high switching characteristics for the adjustable speed drive system causes the overvoltage with steep-fronted waveform on the motor terminals. As this steep-fronted transient voltage in inverter drive loads heavily on the terminal coils of motor winding, the insulation failure in the motor winding occures mostly on the terminal coils. Therefore, it is reasonable to reduce turns of terminal coils only and to increase dielectric strength of interturn insulation. This paper states about the comparison on measured characteristics of normal induction motor and the induction motor with reduced turns of terminal coils and about the comparison on the results measured and calculated by equivalent circuit. The appropriate rate of reduced turns of terminal coils is about 20%.
This paper discusses automatic gain adjustment in a fully-digital-controlled shunt active filter intended for installation on power distribution systems. This is the first step in cooperative control of multiple shunt active filters based on voltage detection for harmonic damping throughout power distribution systems. In general, an optimal control gain is equal to the characteristic impedance of a distribution line. However, it is difficult to know circuit parameters of a real distribution line, which depend strongly on feeder connections, shunt capacitors and loads. Therefore, the main purpose of the gain adjustment is to help the active filter to damp out harmonic propagation without considering the circuit parameters. Moreover, the gain adjustment can reduce the compensating current and losses in the active filter. The active filter having the function of automatic gain adjustment is experimentally compared to that with a constant gain. Experiment results verify the effectiveness of the active filter having the function of automatic gain adjustment.
This paper presents a new position sensorless control system of an IPM motor. The proposed method is based on an injected voltage vector that is synchronized with a PWM carrier of an inverter. From the relation between the injected voltage vector and the saliency of the rotor, it is estimated the pole position. The first current difference vector is detected when the injected voltage vector in the calculated pole position direction is added to the motor control voltage vector. Next, the second current difference vector is detected when the injected voltage vector in the opposite direction of the calculated pole position is added to the same motor control voltage vector. Then, the pole position of the rotor with anti-saliency can be estimated from the first and second current difference vectors. This method needs neither motor parameters nor band-pass-filters. By the proposed control system, the IPM motor can be operated over a wide speed range including zero speed, and controlled with a quick response.
It is important to examine the problems in applying the optimal design method to the practical design of magnetic devices. The “Investigation Committee of IEE of Japan” has proposed “tank shield model” for comparing optimal design methods. This is a benchmark model for reducing the volume of shielding plate and for constraining the eddy current density in the tank within a specified value. In this paper, the tank shield model is optimized using the Rosenbrock's method and the finite element method. The effectiveness of the technique for making the pile in the z-direction of 2-D mesh of quadrilateral element in generating hexahedral elements for 3-D optimization is discussed. It is shown that the reasonable results that satisfy the specified constraints can be obtained using the Rosenbrock's method within the acceptable CPU time. The experimental verification is also carried out.
The immittance converter is the combined word of the impedance-admittance converter. The immittance converter has an input impedance that is proportional to the admittance of the load connected across output terminals. In this converter, the output current is proportional to the input voltage and the input current is proportional to the output voltage. Consequently, it converts a constant voltage source into a constant current source and a constant current source into a constant voltage source. It is well known that the quarter-wavelength transmission line shows immittance conversion characteristics. However, it has very long line length for the switching frequency, and is not suitable for power electronics application. So we proposed immittance converters that consist of lumped elements L, C and show improved immittance conversion characteristics at a resonant frequency. In this paper, we propose a T-LCLC type immitttance converter, which has the transitive configuration and both merits of T-LCL and π-CLC type immittance converter. We show voltage-current transformation characteristics and Frequency characteristics and efficiency characteristics of the T-LCLC immittance converter. These characteristics were determined analytically and experimentally.
Currently ship navigators must manually pick up necessary navigational information from a vast number of charts and sailing directions. They desire essential information for safe and efficient navigation from them. In this paper, we propose an automatic retrieval system for Japanese nautical charts and articles of sailing directions, which is composed of a general purpose database, a retrieval algorithm and a user-friendly inter-face. The database contains the labels of 781 sheets of Japanese nautical charts and HTML files of sailing directions' articles. The database of sailing directions contains articles of Seto Inland Sea Sailing Directions. They are classified into 2, 000 areas and items. When the user inputs a navigational route in terms of the departure port, altering points and arrival port on digital chart of his graphic display by a mouse pointer device, the system can retrieve and show relevant charts and articles for the route. Our system can save time considerably, compared with manual operation. Moreover, it retrieves relevant navigational information from the database without anv omissions.
We propose a multi-modal information filtering technique for attaining dependable and free access to heterogeneous data in decentralized information and control systems. It takes into consideration the difference in the quality of the information on control schedule, management data for real-time control, and so on. The architecture extends the conventional model called data field (DF). In order to prevent the turbulence from an information system affecting a real-time control system, the developed architecture and technique enable to limit the multicasting range of a message respectively on DF, Multi-Cast Group (MCG) and Mode, and a DF can provide plurality of network segments as the information sharing media. Moreover, It is shown that the information filtering technique can also treat the conventional online test method systematically. The developed architecture has been applied to various real industrial production systems and its effectiveness been verified.
Three-phase generator with high temperature superconducting bulk permanent magnet was produced experimentally. The YBaCuO bulk was cooled to 77K, and magnetized by the pulse magnetization method. The induced electromotive force of the sine wave is obtained by the magnetic field distribution of a conic type.
This paper presents a new conceptual electromagnetic induction eddy current-based involuted type heat exchanger for hot water producer and boiler, which are suitable and acceptable for consumer power application. In addition, an edge-resonant PWM high frequency inverter using IGBTs can operate under a principle of zero voltage soft commutation is developed and demonstrated for an induction heated hot water producer and boiler. This innovative consumer power electronic appliance using high frequency soft switching inverter is discussed and evaluated on the basis of simulation and experimental results.