In this paper, we propose a novel gate power supply circuit for high voltage GTO valves. The main feature of our circuit is the configuration itself that a power supply circuit is integrated into a snubber circuit of each GTO. A part of energy stored in a snubber capacitor is transferred to a power supply capacitor and the transferred energy is provided for a gate drive circuit. A concrete design of our circuit is represented according to a gate drive power which is necessary for each of series-connected GTOs. We verify the availability of our circuit using several successful simulation and experimental results.

抄録全体を表示

A simple and reliable contact-less battery charger for electric vehicles is proposed. It's feature is one body of a power factor correction(PFC) converter and a high frequency inverter(HFI) where the low side switch of an HFI works also as the boost switch of an PFC in discontinuous conduction mode which results in high input power factor and low harmonic distortion without any feed-forward control. The exiting current of the inductive connector, complied with SAEJ1773, effectively works to make the converter operating in ZVS condition. Another feature is that the charger is controlled by only one magnetically coupled variable frequency oscillator which was developed by the authors. This paper analyzes the circuits, gives a design example, shows the inductive connector and the oscillator, and experimental results. An 1.7kW output prototype charger achieved charging efficiency of 87.4% among total one cycle charging, over all efficiency of 90% at heavy load and over 98% of input power factor.

抄録全体を表示

Unbalance load compensation for an electrolytic capacitor-less converter/inverter of the flywheel long life uninterruptible power supply which rating of 3 phase, 200V and 5kW-1min is described. The compensation has following characteristics.
(1) Automatic output voltage balancer to cancel output voltage offset and output unbalance of 3 phase inverter.
(2) An input negative phase sequence current controller to compensate input current harmonic distortion at unbalanced loads.
(3) Automatic gain control on converter to improve input currents and transient states.
The UPS has excellence test results which are obtained such as total harmonic distortion THD of input current of 1.2% and 2.0% at 2.6kW single phase load and single rectifier load, respectively. Output voltage offset and unbalance are compensated by automatic output voltage balancer under 0.5s.

抄録全体を表示

Since 1950s, vibrations in the drive-rotor-effector system (rotor system) have been researched without losing interests. An application of rotor system, for example, a flywheel energy storage system, is recently focused on. Therefore the analysis of the rotor vibrations at the critical revolution speed still seems to be a substantial topic. In the mechanical engineering field, the dynamical behavior of the rotor is discussed by means of the simplified model, that is Jeffcott rotor. Most of the studies deal with the amplitude of the whirling motion of the rotor under the assumption that the revolution speed of the rotor is regarded as a input. In general, however, the input from a drive (i. g., motor, engin, and so on.) to the rotor is torque. So it seems important to discuss the behavior of the system under the situation that torque is engaged as a input to the rotor. In this paper, a whirling motion in a DC motor-rotor-DC generator system used as a rotor system is experimentally discussed based on the output voltage of the generator. The results show that at the mechanical resonant state, the hunting appears to the revolution speed of the rotor even in the constant input torque situation. Furthermore it is clarified that the output voltage shows quasi-periodicity, multifractal, mode-lock and chaotic oscillations, and the existence of hysteretic jumps at the appearance and the disappearance of the oscillation.

抄録全体を表示

Web tension control system is regarded as a large-scale system composed of a number of subsystems associated with tension control and speed control. Then the control system should preferably have a decentralized information structure. Since the concept of a subsystem comes from the controller design strategy, the system decomposition is not unique. This paper proposes an overlapping decentralized control methodology for a web tension control system. By employing the overlapping decomposition, the interactions among subsystems are purely disturbance in terms of physical variables. In this case, it doesn't require crossover frequency assignment to each subsystem, and all the interactions are to be minimized. H-infinity controller design procedure is adopted for constructing decentralized controllers. The calculated results confirm the significant advantage of our methodology.

抄録全体を表示

In conventional three-phase rectifiers, it was necessary to use a transformer to obtain low output voltage. In this paper, we propose a new three-phase rectifier circuit that achieves low voltage by using a very simple circuit configuration that does not have a transformer and does not need any complex control. We also describe the operation principle of the proposed circuit, and derive a theoretical formula for its current waveform. On the basis of this formula it also explores the theoretical input/output current characteristics, theoretical current amplification factor, and theoretical output voltage characteristics. Comparisons of these theoretical values with experimentally obtained input/output current characteristics, current amplification factor, and output voltage characteristics, allowed us to confirm the soundness of our theoretical analyses.

抄録全体を表示

Dual Excitation Multiphase Electrostatic Drive (DEMED) is a synchronous motor that is driven by electrostatic force. Because of its light weightiness, thinness and large power per weight ratio, it is expected as small-size motor and high-power motor in the future. Among three types of driving method that had been formerly developed for the motor, single frequency method is the most useful since it needs the least number of phases (three) of power supply. However, when the method drives the motor at such a very low speed as 10μm/s, the force generation decreases, and transformer cannot be used to obtain high voltage for the motor drive. In order to solve these problems, this paper proposes a novel supplemental operation method. In the new method that is named as “modulation drive, ” a 3-phase ac signal is amplitude-modulated with higher frequency carrier signal and applied to the electrodes. Being applied to the single frequency method, the modulation drive successfully drove the motor with typical audio power operational amplifiers that were boosted by transformers with ferrite core, and eliminated the force degradation at low driving speed. Additionally, the force generation of the modulation drive was analyzed, and the result agreed very well with experimental result.

抄録全体を表示

This paper deals in an Active Power Filter to reduce harmonics generated by PWM converters with GTO thyristors of electric railway vehicles. Parallel oscillation frequency components of electric motor vehicle affect substation equipment due to enlarged harmonics. This paper reports an on-board single phase Active Power Filter with compensating power of 200kVA for the purpose of restraining parallel oscillation and test results on its effectiveness.
The Active Power Filter has following features. (1) Harmonics voltage detection from a summation of second winding voltages instead of harmonics current detection. (2) Serially connected capacitor charged by the fundamental frequency voltage that realizes a convertor of the Active Power Filter with smaller output.
Test results with a Star 21 Shinkansen train showed a harmonics current reduction of 1.5_??_2.0kHz, 3/10 of the level that can be attained without Active Power Filter. Furthermore, we expect that the output power of Active Power Filter can be reduced when the design of main transformer is opetimized.

抄録全体を表示

In this analysis method, electromagnetic force calculated by 2-dimensional analysis is transformed into external force for 3-dimensional structural-vibration analysis. And a modeling procedure for a vibrating structure is developed. Further, a space-modal-resonance criteria which relates electromagnetic force to structural-vibration or noise is introduced. In the structural-vibration analysis, the finite element method is used; and in the noise analysis, the boundary element method is used. Finally, vibration and noise of an induction motor are calculated using this criteria.
Consequently, high-accuracy modeling is achieved and noise the calculated by the simulation almost coincides with that obtained by experiments. And it is clarified that the-space-modal resonance criteria is effective in numerical simulation.

抄録全体を表示

A doubly-fed flywheel generator-motor consists of a wound-rotor induction machine and a cycloconverter or a voltage-source PWM rectifier-inverter which is used as an ac excitor. Adjusting the rotor speed makes the generator-motor either release the kinetic energy to the power system or absorb it from the power system. Thus, the generator-motor has the capability of achieving, not only reactive power control, but also active power control based on a flywheel effect of the rotor. A 200-MJ flywheel generator-motor for the purpose of line-frequency regulation on a 132-kV bus has been installed and commissioned by the Okinawa Electric Power Company. However, little literature has been published on control strategy and dynamic performance analysis of doubly-fed flywheel generator-motors. This paper proposes a new control strategy for a doubly-fed flywheel generator-motor, which is characterized by the combination of vector control and decoupling control. The control strategy enables the flywheel generator-motor to perform active power control independent of reactive power control even in transient states. The validity of the theory developed in this paper, along with the effectiveness of the control strategy, is confirmed by computer simulations using EMTDC. In addition, this paper discusses the transient behavior of a magnetizing current of the flywheel generator-motor. The flywheel generator-motor based on leading edge power electronics and electric machine technologies shows promise as a versatile power conditioner, in particular, being capable of repetitively absorbing or releasing electric energy for a short period of time less than a minute.

抄録全体を表示

In this paper, we propose a novel switching method for shortening block feeding portions in short secondary member linear motors. The proposed method involves shifts at every coil, which makes the length of feeding portions much shorter than that in the ordinary method with the shifts at every block section. Resulting advantages for adopting the proposed method are summarized as follows:
1) Concerning power supply: Owing to the extremely short feeding portions, improvement of power factor and efficiency becomes possible. And, since power is supplied to each coil for a very short time, the rating becomes a short-time one.
2) Concerning electric transient phenomena: By short-circuiting coils at both ends of the feeding portion during shifts, continuous power supply and smooth shifts become possible, reducing electric transient phenomena.
The study is carried out through experiments as well as simulations using a hybrid method of the magnetic-fields and the electric-circuits analysis.

抄録全体を表示

Recently, a linear motor has become major interest as a direct drive type actuator that can realize linear motion without auxiliary mechanism. A linear DC brushless motor (LDM) is suitable for a high-accuracy servo with small size. In the LDM, the loading mass changes its values in dependence on the operating condition, and the gravity of the loading mass on a slope becomes disturbance for the control system. The damping coefficient of the LDM changes with the contact surface between the linear guide and the mover. It is difficult to keep the condition uniform. Then, parameter variations in the LDM should be considered to be large. In order to overcome above points, an adaptive identification method is applied for estimation of the loading mass, the damping coefficient and disturbance and pole assignment type positioning controller is designed using the identified loading mass. In experimental studies for the LDM, overshootless positioning control is realized in the maximum velocity for different LDMs or loading masses.

抄録全体を表示

The torsional vibration is often initiated by the momentary impact which occurs when a load is connected to aa motor by several mechanical coupling parts. To suppress the vibration generated in a multi-mass plant, many control methods have been developed for practical use. In this paper, the authors propose a simple vibration suppression strategy which employs two variable parameters consisting of resonance ratio and damping factor along with a state feedback approach. The control performance is verified by simulations.

抄録全体を表示