This paper proposes an application of electric double layer capacitor (EDLC) to single-phase composite PWM voltage source inverter (VSI). The VSI consist of the normal single-phase bridge circuit and an additional arm. The two auxiliary self-turn-off devices of the arm avail to adopt a composite PWM control, which contributes to reduce the ripple in the ac output current. In the dc side, the dc current contains the ac component, which has twice the system frequency. Until now, LC series resonance circuit tuned to twice the utility frequency is necessary to connect to the smoothing capacitor in parallel. Hence, the smoothing capacitor is drastically reduced. The VSI is disadvantageous in maintenance to use storage battery in order to stabilize the dc voltage.
This paper describes an application of EDLC to smoothing capacitor in the dc side of the PWM VSI. The EDLC absorbs the ac component with twice the utility frequency and the ripple caused by PWM switching included the dc pulsating current. The smooth dc current is obtained by using the EDLC.
The experiment shows that the single-phase composite PWM VSI used for the utility connected residential photovoltaic power generation system (PV system).

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Permanent magnet synchronous machines (PMSMs) have been used in various applications owing to the high power density of the magnets. Especially interior permanent magnet synchronous machines (IPMSMs) are attractive in high power density applications since IPMSMs can generate both magnet torque and reluctance torque, and the field weakening control can reduce the output voltage.
However, a lot of field weakening current is required to generate a lot of reluctance torque, the carefully magnet design, the thick magnet is used, is needed not to demagnetize the magnet. Hence, the cost of the magnet increases and the operating temperature is limited.
In this paper, a field intensified IPMSM (FIIPM) is proposed. The proposed FIIPM has a forward saliency and the positive current on the direct axis is added in order to the magnet to generate a reluctance torque. The technique of adding the positive current contributes the magnet not to demagnetize, and using a thick magnet to protect from the demagnetization is not necessary.
This paper shows that IPMSMs are difficult to generate more reluctance torque than magnet torque by using a relationship between saliency and torque ratio. The FIIPM is introduced as a possible design option for high reluctance torque machine. The general characteristics of FIIPMs are analyzed using finite element analysis (FEA).

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In this paper a drive for a symmetrical two phase induction machine using vector modulation is studied. A comparison is made among different types of space vector modulation (discontinuous and continuous) and a new one is proposed. The concepts of vector modulation are reviewed. Experimental results to validate the theoretical statements are shown.

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Power semiconductors can be modeled as a thermal network of resistors and capacitors. The thermal boundary condition of such a model is typically defined as the heat sink surface temperature, which is assumed to be constant. In reality, the heat sink surface temperature underneath the power module is not exactly known. In this paper we show how to set up a thermal model of the heat sink in form of a RC thermal equivalent network that can be directly embedded in any circuit simulator. The proposed thermal heat sink model takes into account convection cooling, thermal hotspots on the heat sink base plate, thermal time constants of the heat sink, and thermal coupling between different power modules mounted onto the heat sink. Experimental results are given and show high accuracy of the heat sink model with temperature errors below 10%.

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It is necessary to develop high efficiency motor, however, it comes a limit to increase efficiency because many motors already have very high efficiency. It is reported that iron loss of motor increase by shrink fit. Therefore, new motor shape is developed from a viewpoint of decreasing stator core stress caused by shrink fit. The relationship with iron loss and stator core stress is examined by the analysis, and the effect of new stator core is verified.

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The transient surge measurements at the changeover sections of Shinkansen power feeding system were carried out in some substations and sectioning posts. The detail of the surge voltage phenomena was investigated and the reason of the frequent discharge of the lightning arrester was clarified. As one of the solutions to avoid such a severe transient phenomena, a novel power supply system for a changeover section substitution for the conventional system with a pair of the vacuum switchgear was proposed. To realize a stable running through the changeover section where two power sources with phase difference are faced, some special control methods were introduced and their validities are confirmed by not only the computer simulations but also the mini-model experiments.

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An electrical system for wind turbines using cage induction generator with back to back converters for connection to the network is experimentally tested under short circuit conditions in a 55kW generator set-up. 50% voltage sag is realized in the laboratory set-up to investigate the performance of the power electronic converters control under the newly introduced grid codes. Standard vector control techniques are implemented with the aim to maintain balance between generated power and power supplied to the grid. The robustness of the power electronics converter is experimentally analyzed under the short circuit for different settings of the converter nominal current and the converters are found to be robust against voltage sags.

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This paper presents an adaptive dead-time compensation of voltage source inverter for variable speed drives. An evaluation index is developed to determine the magnitude of dead-time compensation voltage on-line. The evaluation index offers exact and quick identification. Furthermore, motor parameters are never used in this method. Experimental results verify that the distortions of phase current and commanded voltage are suppressed by applying the proposed dead-time compensation strategy.

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This paper describes a study targeting a 100kW power range converter to the fuel cell electric vehicle (FCEV). The proposed power converter offers the solutions in both high-power and high-efficiency applications. The power supply consists of new topologies based on Quasi-resonant Regenerating Active Snubber (QRAS) and new devices “SiC schottky diodes", which are already on the market as the next generation of power devices substituted for Si semiconductor devices approaching the theoretical limits of the Si material. The configuration and the performance of 8kW one-tenth-prototype SiC-QRAS are followed by this report on the successful test evaluation results.

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In recent years, voltage sags have become a very important power quality issue. Voltage sags often interrupt manufacturing processes and result in significant losses. To improve the quality and reliability of electric power, more and more utility companies provide dual power feeders to high-tech manufacturers. The solid-state transfer switch (STS) based on thyristors can utilize the dual power feeders to protect sensitive loads against voltage sags. Conventional STS may require more than a quarter cycle to complete the transfer process depending on the operating condition of its loads. In this paper, an improved STS with resonant impulse commutation circuit is proposed. The proposed system can greatly reduce the transfer time and provide better protection against voltage sags. Laboratory test results are presented to validate the performance of the proposed STS system.

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This paper presents an integrated pulse width modulator with dead-time generation capability. The proposed modulator can place proper dead-time around gating pulses while maintaining the correct volt-second of the output voltage on a pulse-by-pulse basis. The proposed method is suitable for digital implementation of PWM, and the required computational resource is very low. Compared to the conventional dead-time compensation by average voltage correction, the proposed method provides improved accuracy of output voltages and hence better dynamic response. Experimental results are provided to verify the proposed method. Comparisons with other dead-time generation/compensation method are also presented.

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Powering terminal should prevent signal inflow from the communication lines. Powered terminal in most wire communication systems needs to separate ac signals and dc supply power in its input part connected to the communication lines. Our original communication system consists of low-power dc-dc converters. In our system, the direction of dc power is opposite in powering terminal at reception and powered terminal. Therefore, to use the same electronic choke for powering terminal and powered terminal, it is preferable that the electronic choke be bidirectional. So, we have proposed new electronic choke by the use of small inductors and an amplifier. From the viewpoint of power distribution, this system contains a parallel-connected dc power supply. In this paper, voltage-ripple attenuation characteristics at reception are presented on the dc power distribution system using buck-type converters and new electronic chokes. New electronic choke has an ability of good attenuation against signals. Even though switching frequencies are different, no beat is observed in the output dc voltage waveform of powered terminal. New electronic choke effectively removes circulation or interference by the ripple.

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This paper presents a hybrid energy storage system mainly based on Compressed Air, where the storage and withdrawal of energy are done within maximum efficiency conditions. As these maximum efficiency conditions impose the level of converted power, an intermittent time-modulated operation mode is applied to the thermodynamic converter to obtain a variable converted power. A smoothly variable output power is achieved with the help of a supercapacitive auxiliary storage device used as a filter. The paper describes the concept of the system, the power-electronic interfaces and especially the Maximum Efficiency Point Tracking (MEPT) algorithm and the strategy used to vary the output power. In addition, the paper introduces more efficient hybrid storage systems where the volumetric air machine is replaced by an oil-hydraulics and pneumatics converter, used under isothermal conditions. Practical results are also presented, recorded from a low-power air motor coupled to a small DC generator, as well as from a first prototype of the hydro-pneumatic system. Some economical considerations are also made, through a comparative cost evaluation of the presented hydro-pneumatic systems and a lead acid batteries system, in the context of a stand alone photovoltaic home application. This evaluation confirms the cost effectiveness of the presented hybrid storage systems.

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This paper introduces an average circuit model for switch mode shunt converters coupled with power systems such as active filters (AF) and static compensators (STATCOM). These devices absorb or deliver reactive power to the utility network by employing a variable switching frequency modulation scheme (e.g. hysteresis current control). Analysis and simulation of these exact devices could be complex under transient and steady state conditions. Here the variable switching frequency shunt devices are modeled using an averaging approach, deriving averaged mathematical and circuit models. Further, the ripple is approximated to provide a correction to the average model. The resulting models produce much faster simulations than their exact devices. Theoretical considerations show that the averaged model agree well with the original system, and this is confirmed by PSpice and MATLAB simulations, as well as experimental results.

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The diode rectifier offers several desirable features such as a unity displacement-factor and a high efficiency with low complexity and high reliability, but the utility line-current is significantly distorted. The traditional multi-pulse (e.g., 12-pulse, 18-pulse and so on) PAM concept by means of multiple rectifier units and phase-shifting isolation-transformers is a well-known scheme to improve the input line-current waveform and reduce dc-current/voltage ripple. Though, the necessity of the isolation-transformer is a great weak point especially for applications in low to medium power range. To mitigate the problem, several investigations have been done. The PWM rectifier is a modern and effective alternative, although it results in a higher initial cost, lower efficiency and EMI noise problems due to high frequency switching.
To solve the problem, we have two alternatives without PWM and are so called “Passive” schemes. One is the multi-pulse/multi-phase scheme without the isolation transformer but with an autotransformer. This scheme results in a simplified multi-pulse PAM rectifier. The other is the Third-Harmonic-Current Injection and the expanded schemes. Although these two schemes have been studied independently in most cases, new types of diode PFC rectifier obtained by combining the two schemes have been studied recently. Additionally, further new topologies, so called “Hybrid” type, have been proposed very recently. The rectifiers with the new concept consist of an autotransformer-connected double 3-phase bridge 12-pulse rectifier and a PWM dc-dc converter on the dc-side to perform the current injection. The Hybrid rectifiers offer output voltage controllability and sinusoidal input currents similarly to the PWM rectifiers.
To show the current trends and remaining possibilities of the Passive and Hybrid rectifiers, this paper gives a survey and historical review of the rectifiers. Then, some new topologies in the category are investigated. Simulation and experimental results of the rectifiers are described to explore the operating mechanism and to obtain hints to achieve new topologies.

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The converters with high power output density has been envisioned for next generation. The key to realize that is operation at very high switching speed and utilization of ultra low loss of power semiconductor devices in wide bandgap semiconductor e.g. Silicon Carbide and superjuction. The power loss by main junction capacitance, C_oss intrinsically structured inside the device has been reported but the quantitative study is not adequate. In this study, for 3kW converters, the loss by C_oss is theoretically and experimentally proved using heat measurement with resistive and inductive load chopper circuit with 500V Si-MOSFET and 600V Silicon Carbide Schottky barrier diode. Moreover since large loss remained other than already known loss factors has been quantitatively revealed, and it is suggested that this remained loss will be a next target for further reduction of switching loss.

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This paper presents theoretical studies and practical results obtained with a four-wire shunt active power filter fully controlled with neural networks. The paper is focused on a current compensation method based on adaptive linear elements (adalines), which are powerful and easy-to-use neural networks. The reader will find here an introduction about these networks, an explanatory section about the achievement of Fourier series with adalines, and the full description of an adaline-based selective current compensator. The paper also brings a quick discussion about the use of a feedforward neural network in the current controller of the active filter, as well as simulation and experimental results obtained with the prototype of an active power filter.

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The use of the interior permanent magnet synchronous motor (IPMSM) has increased in the industrial field because of its excellent characteristics, such as high efficiency, wide range of speed operation and flexibility of the rotor structure. Therefore, the IPMSM, especially one using the rare earth permanent magnet, is being actively studied.
In the IPMSM using the rare earth permanent magnet, typically the permanent magnet is deeply embedded in the rotor. However, torque performances are significantly influenced by the rotor structures. This paper describes the torque performances for a single-layer IPMSM using the rare earth permanent magnet when the permanent magnet arrangements are changed.

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This paper concerns a control method in which cold cathode tube used for liquid crystal display, etc. is made to light at maximum efficiency. In the system composed of inverter, LC circuit, piezoelectric transformer and cold cathode tube, tube current is controlled at the height of inverter output voltage, and the efficiency is controlled at the frequency. Like this, maximum efficiency control which does not depend on tube current is realized by carrying out tube current control and efficiency control separate. Maximum efficiency control method is deduced, after the characteristics of piezoelectric transformer and cold cathode tube is well examined, and the performance of the control has been confirmed by simulation and experiment.

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This paper proposes a new well-organized dynamic mathematical model and new dynamic vector simulators for newly emerging self-excited hybrid-field synchronous motors (SelE-HFSMs) that have rotor field by both permanent magnet and diode-shorted field winding. The proposed new mathematical model has the following completeness and generality: 1) it consists of three consistent basic equations such as circuit, torque-evolution and energy-transmission equations; 2) it deals with pole saliency and contains nonsaliency as a special case; 3) it is a dynamic model and contains static one as a special case; and 4) it is established in the general reference frame including the stator and rotor reference frames as special cases. The proposed new dynamic vector simulators are established in form of vector block diagram based on the new model. They have the following attractive features: 1) they succeed in realizing clear configurations with physically meaningful vector signals, which clearly show motor electromagnetic mechanism; 2) vector signals utilized as transfer signals between blocks are defined in the general reference frame; consequently, the simulators in the frame can be directly and easily reduced to the ones in the stator and rotor reference frames; 3) they are compact, and can be easily programmed by commercially available standard simulation software. Two typical and compact but sufficiently general dynamic vector simulators are newly presented. Validity of the model is verified analytically, and validity of the simulators is confirmed by numerical experiments.

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The unevenness of contact line is one of the factors that considerably affect the dynamic characteristics of contact line and pantograph system. This paper describes the methods to estimate the static installation quality of contact lines by calculating dynamic characteristics and reports some examples of the estimation of real line conditions. The dynamic characteristics, such as contact force fluctuations of pantographs and motion of contact lines, are calculated from the measured unevenness of contact wires, and the calculated results are diagnosed quantitatively. It is confirmed that the calculated values agree well with the measured values. This method is expected to contribute to efficient maintenance of contact lines for high-speed operation.

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This paper proposes the algorithm for the initial pole-position estimation of a surface permanent magnet linear synchronous motor (surface PM-LSM), which is carried out under the closed loop control without a pole sensor and is insensitive to the motor parameters. This algorithm is based on the principle that the initial pole-position (IPP) is calculated by the reverse trigonometric-function using the two reference currents, which are informed from the speed controller. The effectiveness of the proposed alogoritm is confirmed by testing a surface PM-LSM with large disturbance. IPP is well estimated within a satisfied moving-distance and a shorter estimation taken-time even if large disturbance such as cogging and friction are existed.

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In this paper, novel direct yaw-moment control (DYC) with road condition estimation and anti-slip control is proposed for electric vehicles. An inner-loop observer controls the vehicle traction, and an outer-loop observer stabilizes the yawing motion of the vehicle. An immeasurable parameter known as cornering stiffness is estimated from the detected yaw-rate, steering angle, wheel speed and yaw-moment observer output in real time. Thus, the accurate control input can be generated with the estimated parameters. The proposed adaptive control is compared with a conventional robust control method on dry and snowy terrain conditions. Experimental results show that the proposed control algorithm properly attenuates the yaw-rate error.

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This paper inquires by proposing the control system which improves OPU (Optical Pick Up) control performance of optical disk system. This system can be realized by adding a correction pulse control block which is based on position error signal, onto a conventional position control loop composed of the PID control rule. By this function, the position error resulting from a physical distortion and acceleration disturbance of disk can be decreased sharply. Furthermore, this system can decrease the deviation caused by the shock disturbance which is not able to be controlled by the PID control rule. In addition, it becomes possible to decrease the overshoot at the impulse response sharply, and realizes stable capture of a target position. Since this system is realizable with simple algorithm, it is possible to adopt to wide-range application.

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Ethylene gas that contains the acetic acid ester element can be removed by applying the pulse voltage to the floating multi-electrode device. This phenomenon is caused in the weak discharge by the strong electric field between the narrow electrodes. This device is possible in very small electric power (<1.5Wh). When this device was installed in the container for preservation, the following results were obtained: Each removal effect of ethylene gas is 16ppm/35min for bananas 10.8kg, 14ppm/6 hour for 50 apples, and 3.5ppm/30min for 2 melons. However, ethylene gas that doesn't contain the acetic acid ester cannot be removed (ex. ethylene pure gas and Japanese apricot).

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The direct and quadrature axes inductances of flux barrier type Synchronous Reluctance Motors (SynRM) change depending on the magnitude of both direct and quadrature axes currents under the influence of the cross-magnetic saturation. This paper presents a maximum efficiency operation method of SynRMs with cross-magnetic saturation. An improved approximate equation that accurately expresses the inductance variation caused by cross-magnetic saturation is utilized for calculating the Maximum Efficiency Operation Current (MEOC, i.e., the d-axis current at maximum efficiency) at each load point. A vector control system in which the steady-state driving efficiency is maximized by selecting a d-axis current command from the obtained MEOC is shown. By considering cross-magnetic saturation the proposed method not only maximizes the efficiency but also improves the torque control accuracy. The validity of this method is demonstrated with calculated and measured results of on-load characteristics.

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This paper proposes a novel iron loss calculation method based on the loss-map of the magnetic materials. The distinctive feature of this method is that the iron loss on the inductors in many kinds of converters can easily be calculated even if the magnetizing conditions of the inductors are different. In this paper, the dynamic minor loop characteristics of the magnetic core on the condition of the switching converter are defined. Then, the dynamic measuring method of the dynamic minor loop by using the chopper circuit is presented. Next, some typical loss characteristics derived from the dynamic minor loop measurement is discussed. Also, a novel loss calculation method of the ac filter inductor on the PWM inverter by using the modified loss-map method is proposed.

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On the operation of coil winding shaped induction heating process, a spark phenomenon often generates and makes a serious problem which affects not only the product quality and equipment damage but also the safety operation. Since the cause of the spark generation is considered to be an induced voltage which induced by the time variation of the width direction magnetic flux, in order to reduce it, we proposed a new type coil winding shape in which the winding coils are rectangular to the running direction of the steel sheet and the return coil is parallel to it. The usefulness of the proposed shape is confirmed by using numerical calculation in electromagnetic field. The induced voltage by the proposed induction heating coil is reduced 84%, though the heating capacity and inductance of the proposed coil is the same as the conventional one.

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Recent advances of motion control technologies make it possible to realize intelligent machine systems. Mobile system such as an electric wheelchair is one of them and it is expected as a support instrument in the future aging society. This paper focuses on a development of electric wheelchair that ride quality becomes high. To address this issue, a vibration control strategies of wheelchair is proposed by using the variation of a rider's COG and resonant ratio control. The validity of the proposed strategy is confirmed by numerical and experimental results.

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The harmonics of the return current may interfere with the signaling current along with the rails. In this paper, we present the theoretical studies of the return current harmonics in the inverter-controlled DC electric railcar, aiming at contributing future work to improve the compatibility with the signaling current.
We theoretically derive sideband harmonics of the DC-link current. Then, in order to verify the theoretical study, we experimentally measure the harmonics and numerically simulate the harmonics. As a result, we concluded the theoretical DC-link current is enough accurate to be utilized for the future improvement of the inverter harmonics current.

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