This paper describes a control method to widen the frequency bandwidth of a voltage control system for a switching regulator, which is based on a coprime factorization description of the system.
First, this paper clarifies the control performance of a conventional voltage control method with a proportional-integral control element and a phase lead element, which does not widen the frequency bandwidth enough. Next, this paper proposes a new voltage control method with a compensator based on the coprime factorization description of the system. The compensator employs a two-degree-of-freedom control system, and is made up of a stabilizing dynamic compensator and a reference signal response dynamic compensator. Futhermore, this paper shows one possible design of the two dynamic compensators, and the simulation and experimental results for the test switching regulator.

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The solar cell has an optimum operating point to be able to get maximum power. To obtain maximum power from photovoltaic array, photovoltaic power system usually requires maximum power point tracking controller. The output characteristics of solar cell are nonlinear, and these characteristics vary with load, solar insolation, cell temperature. Therefore, the tracking control of maximum power point is the complicated problem.
This paper proposes the maximum power point tracking control of photovoltaic array using fuzzy control. To obtain maximum power from photovoltaic array, the fuzzy controller only uses the output power. Therefore this control method is easy to implement to real system. Moreover, this method can track maximum power point rapidly with fuzzy inference even if the optimum operating point changes. The usefulness and validity of proposed control method are proved experimentally under constant natural solar insolation.

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This paper presents a method to analyze magnetic field with accuracy by 2DFEM in shaded-pole type induction motor. That is to say, the equations of electric circuits which consist of the rotor bars are coupled with Maxwell's field equations directly to solve the currents in the rotor bars regardless of ‘grad φ’. And in the same way, all other secondary currents are solved with accuracy. Then the motor torque can be calculated by using the currents and the variations of the interlinkaged flux in the rotor bars.
When the calculated results by this method are compared with the measured results, the good agreement is obtained.

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This paper presents voltage equations and a parameter measurement for synchronous reluctance motors including the stator iron loss. The stator iron loss is modelled by additional windings on three-phase axes. These windings are transformed into d-q axes and are represented as equivalent eddy current circuits. The stator iron loss is introduced as equivalent iron loss resistances in voltage equations on the assumption that the losses in the stator core are produced in the equivalent eddy current circuits on d-q axes. The voltage equations including the equivalent iron loss resistances are derived by use of time constant approximations of equivalent eddy current circuits.
Parameters, which are the equivalent iron loss resistance and the d-q axes self-inductances, in the voltage equations are measured by P-Q circle diagram method. As the P-Q circle diagram method is implemented in synchronous condition, the exactly measurement is possible.

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A pole-changing induction motor with pole-amplitude modulation (PAM) has a single-winding system, and has a unique speed ratio other than 1: 2. It provides an excellent energy-saving property when used for the flow control system of pumps and blowers. This, therefore, has attracted considerable attention in a field of flow control design.
However the method of conversion from an 8-pole to a 6-pole induction motor by using this PAM becomes complicated compared with the method of conversion to a 10-pole motor. In addition, the induction motor designed by this approach is likely to be affected by large harmonic magnetomotive forces, and therefore needs careful investigation in the design.
This paper describes the harmonic torque prevention approach done by using the unified theory of electrical machinery for the case of 8-pole to 6-pole conversion by PAM. From the result of analysis and speed-torque experiment, it is shown that this induction motor is driven by the negative-phase revolving magnetic field due to the 3rd order harmonic, and that there appear 13th harmonic asynchronous crawling torque in motor region and 11th harmonic asynchronous torque in braking region. It is also shown that a long-pitch winding with a machine angle of 8/24 is recommended for the motor design so that the 11th and the 13th harmonic torques are removed.

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A hybrid transducer-type ultrasonic motor serves a high controllability, since the driving force can be controlled independently of the friction controlling component. The torsional vibration velocity has a direct effect on the speed, while the longitudinal vibration controls the traction transmission through friction. We can change the speed smoothly, if we vary the torsional vibration velocity, with the longitudinal vibration being maintained at the optimum value.
This paper presents an experimental study of a speed control system for a hybrid transducer-type ultrasonic motor. First, we utilize an optical rotary encoder to measure the speed of the rotor, and it is feedbacked to the excitation magnitude of the torsional vibration. Stability and transient responses of the speed are improved. Second, we point out that the speed has a linear relation to the current of the torsional port. Then, by monitoring the current, a feedback system can be built without any auxiliary encoders.

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A new control method for Neutral-Point-Clamped (NPC) inverters based on closed-loop regulation of the line-to-line output voltages is proposed. The method uses independent hysteresis comparator controllers to regulate the direct and quadrature axis components of the three phase output voltages. The closed-loop control allows a high performance over the whole range of operation, even when low speed devices such as the GTO are used. A neutral-point potential control is described, which is capable of stabilizing the variations within fixed limits during steady and transient states. Further, a new vector selection technique which used four vectors to generate the sinusoidal output is investigated. The vector selection allows an almost decoupled control of the vector components. The principle of the method is discussed and the vector selection technique is presented. The effectiveness in the output-voltage-waveform generation and the balance of the DC-link capacitor voltages are verified by simulation and experiment.

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This paper presents a buck-boost PWM power inverter and its application for residential photovoltaic system. The PWM power inverter is realized by driving a inverter constructed with a high frequency buck-boost chopper in the discontinuous conduction mode (DCM). Photovoltaic system with the power inverter has the following advantages: (1) The power generated by the photovoltaic array can be transfered to the load and the utility line under any array voltage, (2) Isolation between the photovoltaic array and the utility line is performed by a small high frequency reactor operating as energy storage element, (3) There is no need of a reactor to link the utility line, (4) Unity power factor operation is provided, (5) So the system configuration is very simple. The input-output characteristics of the system is analyzed. As the result, the ripple component of the array current and the power flow between the interface and the utility line are derived, and verified experimentally.

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Superconducting magnetic energy storage (SMES) is considered the next generation technology for storing electrical energy because its energy storage efficiency is higher than that of any conventional energy storage system and its charging and discharging times are short.
This paper discusses the input and output circuits of SMES for DC lines, and it discusses their circuit control methods. The main items in this paper are the follows:
(1) An input circuit using a high-frequency switching control method is proposed, and its stable condition (depending on the voltage range of the capacitor in the input circuit) is derived.
(2) A frequency modulation method for an output circuit is proposed, and simulated results show that this circuit supplies stable power and a constant ripple voltage.
(3) Experimental results of the input and output circuits using a normal-conducting coil and a current-generator are shown to confirm the analysis of the input and output circuits.

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Computers came to play very important roles in our society such as banking, traffic control, and power distribution control applications. Requirement for high-reliable and 24-hour-a-day continuous computation for various application field is soaring in accordance to globalization of economics and human activity. Fault-tolerant computer systems are required high performance, transparency of fault-tolerance and fault-tolerance of fault-tolerance mechanism itself. This paper presents newly developed fault-tolerance technique, TPR (Triple Processor Check Redundancy) method which is suitable for high-performance computing and has transparency of fault-tolerance. Furthermore, the TPR system has fault-tolerance of fault-tolerance mechanism itself by self-checking MPU (Microprocessing Unit) comparators and independent re-configuration control logics for each redundant system.

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To realize the economical and high performance drive for urban transit, a linear motor is driven as a high performance expensive motor or a economical secondary sheet type linear induction motor (LIM) with relative poor performance which is in practical application, by changing the reaction rail, not changing the primary on vehicle. First, it is discussed the secondary wound type LIM without end effect. It is revealed that the wound type LIM has much larger secondary leakage reactance than sheet type LIM, and the performance is not good in this use. Second, the linear synchronous motor (LSM) is discussed as a high performance motor. It is cleared that LSM realizes both the short primary and high efficiency with unity power factor even in the practical section length for the field excitation. So, authors propose the combination use of LSM in power running or braking region and sheet type LIM in other region.

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This paper presents a development of a linear driving apparatus system for the vertical movement system such as ultra super high buildings or deep under ground upto approximatly 50m of depth. The contents deal with as follows.
(1) As a double-sided permanent magnet type linear synchronous motor (LSM) is useful to minimize a magnetic attractive force and can produce a strong thrust with small size, the vehicle weighted 270 kg can be vertically to move up and down 2m smoothly.
(2) Analysis and calculation of the thrust, the influence of each parameter to the thrust, an armature reaction and the magnetic attractive force are examined.
(3) Characteristics of LSM (equivalent circuit, vector diagram) are analysed similar to the rotating synchronous machine and the test results are compared with the calculated values with good agreement.

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