The relations between reluctance motor characteristics and the magnetic properties of core materials are quantitatively investigated using equivalent circuit. High saturation magnetizations are required for core materials. Low iron loss materials are used as stator cores and SRM rotor core. High harmonic frequency is generated even in synchronous RM and then copper losses and iron losses increase. In IPM, reluctance forces are reduced by permanent magnet fluxes superposed in cores, but the force reduction is little in the case of IPM with ferite magnets. The magnetic anisotropic energies of core materials may increase reluctance force if the core materials are used near saturation magnetizations.

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At high speed range in voltage source inverter (VSI) fed permanent magnet synchronous motor gap flux is weakened to limit terminal voltage for saving the capacity of VSI. In weakening flux operation of salient pole PMSM, d-axis current and qaxis current can't be decided deductively due to reluctance torque. To cope with this problem we propose feedback control of motor torque, which is calculated from current, voltage and motor speed. By this control method torque and terminal voltage can be determined without measuring them directly. In this paper, the proposed control system is discribed, the transient characteristic is studied and the test results. Lastly we show make it clear that our method is basically effective for railway vehicle traction.

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Compared to the conventional SRM, fully-pitched winding reluctance motors have a higher salient ratio for a given motor dimensions. In addition, since the generated torque of the motor is determined by a product of the rate of change of mutual inductance with respect to a rotor position and winding current amplitude of the corresponding two phases, the motor is suitable for the bipolar current drives. Accordingly, the conventional general purpose inverter drive of the fully-pitched winding reluctance motor is possible. In this case, the optimum lead angles of voltage plays an important role to obtain the maximum torque and maximum torque/current ratio operations.
In this paper, the scheme for determining the optimum angles of voltage without any measurement, and, the method to evaluate the drive characteristics in the design stage are proposed by a combination of simple magnetic and electrical analysis. The effectiveness of the proposed analytical scheme is verified by a experiment using a 400W prototype fully-pitched winding reluctance motor.

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Due to the public growing concern about the environmental problems, each country in the globe is setting a specific target for the energy consumption cut down in each field. As response to the fact, the air conditioning companies are serving many types of energy efficiency including the PM motor driven compressor machines. Within these motors, the internal buried permanent magnet type(IPM) which is known by its high efficiency due to the use of the added reluctance torque to the normal PM one. In this paper, the maximum phase current efficiency is clarified from the motor equivalent circuit and confirmed by experiment. It is also shown that the IPM driving efficiency is higher than the conventional PM one. The simplicity of the current control method is presented and the lowering capacities efficiency from the maximum one is verified and the difference is acceptable. Furthermore, the motor steady characteristics and their independence from the rotating speed is pointed out. Finally. It is clarified that the sinewave driven motor has a higher efficiency than the 120 degree rectangular wave driven one.

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Permanent magnet synchronous motors (PMSMs) are widely used in many applications as high-performance variable-speed drives. In the traction drives such as an electric vehicle and the compressor drives of air conditioner, a wide constant-power speed range as well as a high efficiency operation are desired. The aim of this paper is to develop the high- performance PMSM, which can offer a high efficiency performance in the high speed region including light load condition as well as a wide constant-power speed range. The simulations show that the proposed interior PMSM, where the reluctance torque is mainly produced and the permanent magnet flux assists torque production, is suitable to achieve such demanded performance. According to such new design concept, the prototype PMSM is designed and several drive tests are carried out. The saliency ratio of the prototype IPMSM is about 5 and as a result the reluctance torque is a main torque component, which is above 70% of total torque. The prototype IPMSM can offer the constant-power speed range of up to 5:1 and the high efficiency drives in the high-speed constant-power region. The proposed IPMSM is suitable for a variable-speed drives requiring a high-speed and constant-power operation.

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This paper presents the parameter measurement of the sensorless PMSM using the sensorless drive system. The parameter measurement schemes of the inductances, the winding resistance and the back emf constant are proposed. The inductances are measured by the current responses when the three kinds of switching pat-terns are applied to the motor at the standstill. The winding resistance is obtained by the relation between the reference voltage and the detected current for the constant dc reference current. The measurement of back emf constant is achieved by using the current estimation error of the sensorless drive which is generated by the back emf constant error between the actual motor and the model in the controller.
The effectiveness of the proposed parameter measurement schemes has been verified by the experimental sensorless drive characteristics using the measured parameters.

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When a squirrel cage induction motor is driven by a PWM inverter, electromagnetic noise different from the one during commercial power source drive is experienced. This is because of sideband wave voltage induced in PWM inverter output voltage. This paper describes the mechanism of electromagnetic noise generation in commercial source drive, then electromagnetic force considering the sideband frequency and voltage content and the mechanism of electromagnetic noise generation in PWM inverter drive. It also refers the sideband frequency and voltage content because of operating time in control.

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The major advantages of Switched Reluctance Motors (SRM) are the simple and rugged motor construction, higher efficiency and low cost power electronics controller. However, SRM has essentially the high torque ripple and the magnetic noise due to its saliency.
This paper presents the examination of a special combination of space harmonics of inductance and time harmonics of current from the standpoint of instantaneous torque. The space harmonics distribution of inductance are closely related to the design of teeth configuration and the analysis shows the optimum combination of motor teeth dimension with current control strategy can improve the torque-per-(amp²) ratio with reducing the torque ripple. The experimental studies using the 1.5kW SRM show the combination of the 3rd space harmonic of inductance with the 3rd time harmonic of current improves the torque-per-(amp²) ratio, while the torque ripple can be suppressed within a reasonable range.

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Transportation systems are used in the field of the Factory Automation (FA) and Logistics for reduce their costs. Currently, rotating machines are used for the drive sources of the transportation system with mechanical conversion systems. The systems are required for the faster, useful and easy operations. These systems are not capable enough to satisfy these requirements. We think that the permanent magnet type linear synchronous motor (PM-LSM) is used for the power sources of the transportation system. In usual, the stator of the LSM is arranged continuously all over the guideway. Therefore, the cost of the transportation system is risen up. So we proposed that the discontinuously arrangement of the stator for transportation system using PM-LSM. The discontinuous arrangement systems with PM-LSM need some technological breakthroughs.
In this paper, we describe the results of the study to realize the discontinuously arranged PM-LSM for transportation system. At first, we study the effect of the magnetic attraction force between iron core of the primary and magnets of the secondary. Next we proposed a simple synchronizing method and try to synchronize by experiments. At last, we describe the limit of the synchronization of the proposed method.

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There are some papers about the vector controlled induction motor systems with the adaptive secondary flux observer. One observer used in the system with speed sensor has the estimators of the primary resistance and secondary resistance. And another observer used in the system without speed sensor has the estimators of the primary resistance and speed. These systems are stable that the induction motor is driven under power running condition, but are not always stable that it is driven under regenerating condition. So far, the stability under regenerating condition is not made clear.
The conventional adaptive secondary flux observer was constituted on dq (fixed) coordinate. In this paper, it is constituted on γδ (rotated) coordinate. The stability of systems on both the coordinates is equivalent. As the state variables of the systems on γδ coordinate are dc, the stability of systems can be investigated around equilibrium points.
As the results of investigation, the stability of systems is made clear under the power running condition and the regenerating condition. The systems are stable under the power running condition as known. But the systems are almost never stable under the regenerating condition, in case the observer has the estimators of the primary resistance and secondary resistance, or the observer has the estimators of the primary resistance and speed. Even the regenerating condition, in case the observer has only the estimator of the secondary resistance, or the observer has only the estimator of the speed, the boundaries of stability extend fairly.
The appropriateness of investigation results is confirmed by the simulations.

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This paper presents a repetitive learning control approach processed in combination with a type-1 optimal digital servo controller which is designed for a series and parallel resonant PWM inverter type DC-DC converter with a high voltage transformer link for a medical-use X-ray power generator. This control scheme is introduced in order to achieve rapid transient and dead-beat output voltage responses without any overshoots in addition to output voltage characteristics with low voltage ripple in its steady-state within widely specified setting ranges of output high-voltage and output current for X ray tube. An effectiveness of the repetitive learning control scheme to achieve a variety of quick transient performances in starting state based on abruptly-changed drooping operation of rectified voltage of input-side in the converter system for X ray power generator is discussed on the basis of computer simulation results and the experimental data. Furthermore, an optimal type-1 digital servo control scheme with error compensation loop is implemented in order to eliminate periodic voltage ripple fluctuations of rectifier circuit with a smoothing filter as well as abrupt voltage drooping in rectified DC input of this converter when X ray power generator is started and to realize stable and reduced voltage ripple operation in an X ray power generator.

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The paper presents the performance of a stand-alone DC Power Supply using a self-excited induction generator. It has been shown that, with a proper selection of shunt and series capacitors, voltage regulation can be improved. The system has been analyzed to find the procedure to estimate the magnitude of series capacitance. Experiments have been conducted to validate the analysis. The system is found to be suitable in applications where the prime mover speed remains more-or-less constant and a restricted load voltage regulation may be acceptable.

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The purpose of this paper is to perform theoretical analysis of active power flowing into, or out of, a series device in a unified power flow controller (UPFC), and to reveal what amount of electric energy the dc link capacitor absorbs or releases through the series device in a transient state. This paper theoretically derives that the electric energy flowing into, or out of, the series device during a transient state is equal to the difference between the energy stored in the line inductance in a steady state before the start of the transient state and that in another steady state after the end of the transient state. This analysis helps us to determine the required capacity of the dc link capacitor, as well as the required response of dc voltage regulation in the shunt device. Experimental results obtained from a 10-kVA laboratory setup agree well with analytical results, as well as computer-simulated results.

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We propose a new design method for the generalized predictive control (GPC) system which realizes the optimal tracking performance. The objective is to design the control system which has the similar feedback properties to the two-degree-of-freedom optimal type-1 servo system. The design procedure consists of two steps. First, we design the optimal GPC system without integrator which minimizes the cost index. Next, we incorporate the integrator into the control system which acts only the case of the existences of a disturbance or a plant perturbation. A numerical example and an application are given to illustrate the effectiveness of the proposed method by comparing with the conventional method.

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In conventional electromagnetic suspension (EMS) systems, the levitation and guide systems are independent of each other, not only from the viewpoint of structure but also as regards control. Consequently, lots of guide magnets and detectors are mounted on the vehicle in addition to the levitation magnets and detectors. Furthermore, guide detectors need their targets laid down along the track. This type of design leads to certain problems such as increased vehicle weight, switching difficulties and structural complications.
The authors propose an EMS system which guides a maglev vehicle using the levitation magnets and detectors. This EMS system is realized through creating a kinetic interaction between the levitation and guide systems of the vehicle. We named this EMS system the guide-effective EMS system. A robust controller design algorithm succeeded in stabilizing the EMS system whose dynamics changes widely according to a load weight and guide rail dimensions. In this paper, the authors explain the kinetic interaction and show the robust controller design algorithm.

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In this paper, a circuit configuration and a principle of a new type series-compensated single-phase active power filter are described. In comparison with a conventional circuit, a filter inductance became unnecessary and a new method of a feedback-control for the output voltage was applied to reduce the voltage distortion. Propriety of this circuit was confirmed by simulation results. As a capability equivalent to a conventional circuit was maintained, the size became small.

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In case of the harmonic compensation based on the detection of the source-current, a problem of the resonance between the AF and an LC filter often arises if an LC filter is connected parallel to the AF. Thus the diturbance observer is introduced to solve this problem. By the estimation of the hamonics disturbance using the proposed disturbance observer, the compensation characteristics of the AF is improved and the resonant current is suppressed. The theoretical analysis and the simulation results are presented in this paper.

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This letter presents a novel initial rotor position estimation for a salient-pole permanent magnet motor. The proposed method is based on the measurement of the resonance frequency of the current between two phases. The basic method is verified by experimxents.

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So far two types of PM vernier motor have been proposed. One type has permanent magnets only on the rotor core, and the other is with them on both the stator and rotor core. On the latter type the proposer, who is one of the authors, previously presented its theory, in which two-reaction theory wasn't described. This paper therefore describes the definition of γ-δ axis and the voltage equation on its coordinate system.

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