A brushless DC motor with the magnetic modulation type differential resolver (MMD resolver) has been proposed. The MMD resolver is unique, and is constructed of 4 sensor coils in the stator. We have presented characteristics of resolver and the open loop performance of motor based on a voltage controlled drive system using lead angle control.
Because of the motor structure with the MMD resolver, several motor parameters should be treated as the function of rotor angle and also the mathematical model of the motors should be written in state equations.
There are few reports mentioning closed loop speed control using this type of motors. So we constructed a speed feedback loop using the MMD resolver signals and evaluated its performance by the original simulation program written in state equations instead of transfer functions, because of their non-linear structures.
And we made a simple real time estimation method of armature currents by inserting the voltage equations of this motor into the speed control programs and solving them simultaneously with the execution of speed control programs. By comparison between the results of measuring and the simulation, and also the currents of estimation and the measuring, we pointed out that motor parameters, motor model, structure of control model and control parameters were appropriate.
And we designed the MMD resolver waveform (magnitude and phase) correction methods to decrease signal error which was generated by special rotor magnet added to produce Z signal function.
We got relatively precise speed feedback signals from them and pointed out that this motor could be used as a speed control motor to use these correction methods.

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We have proposed neural network (NN) to develop new types of the paper currency recognition machines. We have showed various effectiveness of NN recognition method by experimental results. However, there are two themes on the paper currency recognition problem. One is the correct recognition of the objective currency. Another is the rejection of non-objective currencies. Conventionally, we use the template matching method as a post processor to reject the non-objective currencies. However, even objective currency is sometimes rejected by this conventional method owing to its terrible damage. In this paper, to solve this problem, we propose a rejecting method of the non-objective currencies by multi-dimensional Gaussian Probability Density Function (PDF). First, we estimate the PDF of currency vector as the multi-dimensional Gaussian PDF. Second, we get the function value and judge the evaluated currency as the objective one or not by this value. Here, we show the effectiveness of the proposed method using multiple national currencies. Furthermore, we implement the proposed method to the experimental system and discuss the effectiveness on a real time system.

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The three-dimensional magnetic field and eddy current distribution of the 70MW class superconducting generator was calculated by a finite element method. The condition for the exciting armature coil was calculated by the j ω method. In the magnetic flux distribution of the armature winding bore, the analysis value had good agreement with the measurement. An analysis that let the rotor move by the synchronizing speed was also done. The armature voltage for the no-load condition and the armature current for the three-phase short circuit condition obtained by calculations had good agreement with the measurements. The validity of the analysis model for three-dimensional magnetic field analysis of superconducting generator was confirmed from these results. And the synchronous reactances were calculated by these results with eddy current in the facing. As a results, the facing had effect of decrease the synchronous reactance about 5%.

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Recently, due to a rapid increase of demand for air-conditioning in summer, peak power demand is becoming acute increasingly. Therefore, load factor has a tendency to drop every year. The drop of load factor is leading to a drop in utilization factor of the power facilities and an increase in cost of installation.
In this paper, we proposed an energy storage system for peak-cut of power demand, to which is applied large capacity electric double-layer capacitors. This energy storage system has some distinctive characteristics, which are long span of life, maintenance free, preservation of environment, high efficiency at charge/discharge, etc.
This paper deals with the circuit arrangement of the proposed energy storage system, the equalized charge method of the capacitors, the control method of the converter at charge/discharge, Finally, the operation characteristics of this system are evaluated by simulation analysis.

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The magnetic shielding analysis of oxide superconducting plates must consider a condition of the plates to be in a mixed state of superconductivity. In this paper, the magnetic shielding characteristic is analyzed by using the shielding current flowing within a superconductor. In this analysis, the shielding current is limited by the critical current density obtained by the four-probe electrical resistance method or the susceptibility method to consider the mixed state. The results of magnetic shielding experiments agree approximately with the analysis results, when the shielding current is limited by the susceptibility method. When the shielding current is limited by the four-probe electrical resistance method, on the other hand, the superconducting plates shield the magnetic field core effectively in the analysis than observed in shielding experiments.

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In civil engineering, to improve weak foundations, many sand pillars are struck into the grounds using a casing pipe. If the sinking velocity of the sand level in the pipe is measured on-line accurately, a smooth construction can be then achieved. The measurement is reduced to that of a length of the air pillar in the pipe. The authors thus proposed a highly accurate pipe length measurement system, which applied a bank of Kalman filters to a linear dynamic model of the stationary wave generating in the pipe. Although the method realized an accurate on-line measurement of the error rate 0.01_??_0.08%, it was applied only on a stand-still steel pipe.
This paper thus tries to apply the system to the measurement of the actual sand level in a casing pipe. This application encounters, however, two new problems. One is that an electric signal caused by the vibration of the casing pipe superposes to that of the stationary wave in the pipe. The other is that the lengths of the air pillar measured with low and high order modes models are different because of the complicated structure of the pipe.
The paper presents a practical measurement system which overcomes the two problems and realizes an accurate on-line sand level measurement in the pipe.

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Permanent magnet synchronous motor (PM motor) is widely used for several industrial applications. Some applications such as an electric vehicle and a compressor drive require a constant power operation. The operating limits and the constant power speed range deeply depend on the machine parameters. The relationships between the motor parameters and the operating performance have been theoretically examined. This paper examines the performances of the prototype synchronous motors, where a stator structure and a rotor structure of all motors are the same. The permanent magnets are inserted into the rotor slits and the volume of permanent magnet is adjusted to control the magnet-flux linkage. The effects of adding magnet into the rotor on the machine parameters and the operating performance are examined based on the various experimental results. The prototype motor has flexibility on the speed versus power performance by adjusting the volume of permanent magnet. The theoretical results with respect to the operating limits and the motor parameters are also confirmed experimentally.

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In the speed sensorless control of the induction motor, the machine parameters (especially the secondary resistance R₂) have a strong influence to the speed estimation. It is known that the simultaneous estimation of the speed and R₂ is impossible in the slip frequency type vector control, because the secondary flux is constant. But the secondary flux is not always constant in the speed transient state. In this paper the R₂ estimation in the transient state without adding any additional signal to the stator current is proposed. This algorithm uses the least mean square algorithm and the adaptive algorithm, and it is possible to estimate the R₂ exactly. This algorithm is verified by the digital simulations and the experiments.

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A novel electrical energy storage system interacting to a commercial ac network was designed and evaluated by experiments, which consists of an ac/dc converter with a constantly-sampled PWM scheme termed Error Tracking Mode and electrical double layer capacitors paralleled by monitor circuits. The ac ratings are 100V, 500W and 1.0 power factor. The storage capacity is designed to be 500Wh. Since the voltage of the capacitor bank decreases to one-fourth with discharge, a reversible boost-down chopper is inserted between the bank and the ac/dc converter. 95.6% and 95.8% were obtained for the ac/dc converter efficiency in rectifier operation and inverter operation respectively. The average switching frequency was settled between 10.4_??_11.2 kHz for any operating conditions. For the chopper, efficiency values of 94.6% and 93.1% were measured in charge and discharge modes respectively. The storage efficiency of the capacitor bank was 89.8 %. This novel utility-interactive energy storage system has demonstrated good and quick performance.

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This paper proposes a new numerical simulation model of angular transmission error of strain wave gear, and designs a robust speed control system for the robot arm with this angular transmission error. The proposed numerical simulation model can confirm the vibration of the robot arm caused by this angular transmission error. It is very difficult for the conventional control system using both a PI controller and a state feedback to suppress the vibration of the robot arm completely. The proposed robust speed control system, which is a two-degrees-of-freedom control system based on disturbance observer, can suppress the arm vibration. The numerical simulation results show the proposed system well regulates the motor speed and suppresses the vibration of load speed.

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In order to achieve maximum utilization efficiency of photovoltaic energy, photovoltaic power generation system usually requires maximum power tracking control. Since the maximum power point vary with solar insolation and cell temperature, it is difficult to track the maximum power point for the various insolation and temperature levels.
In this paper, it is shown that the derivative (dp_s/de_s) of output power (p_s) with respect to output voltage(e_s) of photovoltaic array is equal to zero at maximum power point. This kind of relationship is independent on the insolation and temperature. So, when the insolation or/and temperaturevarious changes, the corresponding maximum power point can be simply obtained by only controlling its derivative dp_s/de_s toward zero. Based on this concept a maximum power tracking control method is proposed and is complemented with the boost chopper in an utility interactive photovoltaic power generation system. The maximum power tracking control system is constructed and the relating design method is described. It is shown that the presented control system has a high stability to a wide change range of insolation and temperature. Finally, the validity of the proposed method is verified through simulations and experiments.

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This paper presents sensorless PM synchronous motor drives at reclosing an electric supply. To realize the stable restarting, the initial rotor position and speed at reclosing are needed. The authors propose the current vector-based estimation algorithm of the initial position and speed when the armature is shorted by the inverter. The estimated position and speed can be calculated from the direction and amplitude of the current vector, respectively. The effectiveness of the proposed estimation algorithm is verified by experiments using a 6-pole, 1.5kW, 1500rpm test motor. The stable sensorless restarting using the estimated position and speed is achieved.

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A new estimation method of the state of the charge of a lead-acid battery is proposed. This method is based on both the electromotive force and the internal resistance of a battery. The estimating equation is derived from a mesured data using the Least Mean Squre Method (LMS). The experiments are performed to verify of the proposed method.

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A new structure of interior permanent magnet synchronous motor with flux-shortening moving piece is described in this paper. With the help of FEM computation, the flux-weakening effect due to the moving iron piece and the operating characteristics of the motor under voltage and current constraint are obtained. By comparing the characteristics with that of the ordinary motor, it shows that the flux-weakening effect along with the rotating speed bring the motor with extensive constant output operating range as well as high torque under the limitation of voltage with proposed construction. Thus it has significant meaning in the designation of the IPM motors for used in electric vehicles.

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A novel switch-mode single-phase voltage-doubler rectifier, which is not based on the half-bridge topologies, is presented. The boost capacitors are symmetrically arranged to obtain the good current regulation and the voltage across the boost capacitor adds to the supply to pump twice the peak supply voltage onto the output capacitor. The arrangement tested, using three insulated-gate bipolar transistors (IGBTs) and a microcomputer as a PID controller, is implemented and IGBTs are switched at 20kHz, which is out of the audible band. The experimental results confirm that the input current can be sinusoidally waveshaped with near-unity power factor.

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