The Pulse Generators or PGs are equipped to detect the rotor frequency of induction traction motors for the torque control in railway vehicle traction field. Eliminating PGs are preferable from the view points of increasing the reliability of the traction system, reduction of the both initial and maintenance cost and down-sizing induction traction motors. Expecting those merits, we have been studying to apply a sensor less control method to induction traction motor control. Prior to some reports of studies and tests to apply speed sensor-less strategy to railway vehicle traction, we lunched the ideas to apply the speed sensor-less control strategy and results of the studies and the tests. In this paper, we present the novel control method for railway vehicle traction and some results of theoretical study and tests.
An advanced single-phase active power filter for the compensation of instantaneous harmonic components in non-linear load current is presented in this paper. A novel signal processing technique using adaptive neural network algorithm is applied and evaluated for the on-line detection of instantaneous harmonic current components generated by nonlinear loads And the feasibility of this adaptive neural network algorithm is substantially confirmed from an experimental point of view.
In this paper, sensorless control for synchronous reluctance motors (SynRMs) without signal injection and an inductance measurement for position estimation are proposed. In the case of SynRMs, accuracy of inductances is the most important thing to realize precise position estimation because inductances are largely varied by a magnetic saturation phenomenon. Therefore, the inductance measurement method, which can measure appropriate inductances for position estimation, is important as well as a sensorless control method. The inductance measurement based on the observer is discussed, and the measurement method and the parameter adjustment method for improvement in stability of the closed loop are proposed. The proposed method can measure inductances easily and be applied for permanent magnet synchronous motors, too. Finally, the proposed sensorless control method is verified by experiments.
A normally-off type 5.3kV 4H-SiC JFET with low specific on-resistance, called SEJFET (Static Expansion channel JFET), has been fabricated. Its normally-off operation was realized by a thin regrown epitaxial channel layer and using the buried p+ regions as a gate in addition to the top p+ regions. The achieved blocking voltage is the highest class BV among the reported SiC JFET. In a 5.3kV 4H-SiC SEJFET, the lowest specific on resistance of 69mΩcm2. Furthermore, the highest current capability among SiC JFET of 3.3A is achieved. In all reported FETs, the SEJFET has the best trade-off between RonS and blocking voltage (BV), which is about 1/230th lower than theoretical limit of a Si FET. Furthermore, the figure of merit (BV2/RonS) is 407MW/cm2, and this value is the highest among reported normally off SiC FETs.
In this paper, the real-time step length control method for a biped robot is proposed. In human environment, it is necessary for a biped robot to change its gait on real-time since it is required to walk according to situations. By use of the proposed method, the center-of-gravity trajectory and swing leg trajectory were generated on real-time with that its command value is the step length. For generating the center-of-gravity trajectory, we develop Linear Inverted Pendulum Mode and additionally consider walking stability by ZMP. In order to demonstrate the proposed method, the simulation and experiment of a biped walk is performed.
This paper presents the effective operation method by interdependent use of capacitor energy on the new concept of voltage transient sag compensator. This compensator consists of the series connection inverter units, and each inverter unit generates a different output voltage by 2n times. Namely, in this system, the compensation energy is accumulated in each inverter unit's capacitor charged with different voltage by 2n times. The method proposed here, in any case of various levels of transient voltage sags on different phase of a power line, provides the effective use of capacitor energy of all these inverter units.
In this paper, a new modulating signal for pulse width modulation (PWM) inverter system suitable for Permanent Magnet synchronous motor (PMSM) drive is proposed. The PMSM with the sinusoidal electromotive force (EMF) driven by the non-sinusoidal PWM voltage generates a torque ripple. And, the torque ripple is similarly generated in PMSM with the trapezoidal EMF driven in the sinusoidal PWM voltage. The new PWM strategy makes a great improvement of the characteristics in the three-phase PWM inverter for the PMSM. The proposed PWM strategy can reduce torque ripple more than sinusoidal PWM method. Although the output voltage waveform is a non-sinusoidal waveform, the motor driven by the proposed modulating signal produces approximately constant torque. By using the proposed modulating signal, the amplitude of the fundamental component is increased more than that of a conventional sine wave inverter. The usefulness of the proposal method was confirmed by a theoretical analysis, the simulation by modeling the system, and the experiments.
This paper describes a novel strategy of maximum-power-point tracking for photovoltaic power generation systems. A unique feature of this method is capability to seek the maximum power point using only a single transducer, i. e., a Hall-effect CT or an isolation amplifier. Output power of the photovoltaic can be estimated with an average value and ripple amplitude of the detected reactor current or the capacitor voltage. A conventional hill-climbing method is employed to seek the maximum power point, using the output power estimated with only the current or voltage transducer. In this paper, not only a theoretical aspect of the proposed method is discussed, but also experimental results are presented to prove feasibility of the method.
Operations trainings of nuclear power plants are performed in full-size power plant simulators. The training is always recorded on videotapes. Many examples such as optimal and not optimal operations are included in the video images. This paper proposes a detection and posture recognition method of nuclear power plant operators from the video images. Posture recognition is one of the most difficult tasks in image processing, because an operator usually takes various postures during power plant operations. To recognize their postures, the method uses the four postures that have been classified by the cognitive scientists engaged in human factors research of nuclear power plant operations. In the method, silhouettes of the operators are detected by several image processing techniques such as a background subtraction, noise reductions and etc. The detected silhouettes are classified into the four postures by their moving speed and a machine learning. Their operations are summarized and visualized with human body computer graphics (CG). In evaluation experiments with over twenty thousand images, the detected silhouettes were classified to the four postures successfully and the operations training were summarized with the human body CG based on the classified postures.
The goal of this research is to develop an intelligent wheelchair (IWC) system which aids an indoor safe mobility for elderly and disabled people with a new conceptual architecture which realizes autonomy, cooperativeness, and a collaboration behavior. In order to develop the IWC system in real environment, we need design-tools and flexible architecture. In particular, as more significant ones, this paper describes two key techniques which are an evolutionary simulation and an overall control mechanism. The evolutionary simulation technique corrects the error between the virtual environment in a simulator and real one in during the learning of an IWC agent, and coevolves with the agent. The overall control mechanism is implemented with subsumption architecture which is employed in an autonomous robot controller. By using these techniques in both simulations and experiments, we confirm that our IWC system acquires autonomy, cooperativeness, and a collaboration behavior efficiently.
This paper presents a novel residual vibration suppression methodology for the repetitive fast-response and high-precision positioning in machine tool drives. In sequential positioning motions, as the interval period of position references becomes shorter, the residual vibration in response due to undesired initial values deteriorates the positioning accuracy, since the positioning controller is generally designed on the condition that initial state variables are zero. In this research, an Initial Value Compensation (IVC) approach is proposed under the theoretical study on effects of the initial state values on the position transient response. The IVC can appropriately assign poles and zeros of the transfer characteristic of position output for the initial values by applying an additional input corresponding to the initial state variables, enabling the response to be residual vibration free. The desired positioning performance, as a result, can be achieved in repetitive motions with arbitrary interval period. The effectiveness of the proposed compensation has been verified by numerical simulations and experiments using a positioning device of industrial machine tools.
An artificial neural network (ANN) based designing method has been proposed for induction motors. Based on the real design data for various types of induction motors with different rating, three-layered cascaded artificial neural networks have been specified and trained to estimate the fundamental quantities and parameters, and also to give proper sizes of the target induction motor. Totally, thirty-four cage rotor type induction motors, which were designed by different engineers, have been selected for the training data. These induction motors have different ratings, different capacities, and different usage, i. e., driving units for pumps, compressors, and fans. The type of cooling method is totally enclosed the fan cooled type for all the selected induction motors. Through the numerical simulations based on the actual design data for different types of induction motors, the efficiency of the proposed designing system has been demonstrated.
We study an adaptive control technique for multi car elevators (MCEs) by adopting learning automatons (LAs.) The MCE is a high performance and a near-future elevator system with multi shafts and multi cars. A strong point of the system is that realizing a large carrying capacity in small shaft area. However, since the operation is too complicated, realizing an efficient MCE control is difficult for top-down approaches. For example, “bunching up together" is one of the typical phenomenon in a simple traffic environment like the MCE. Furthermore, an adapting to varying environment in configuration requirement is a serious issue in a real elevator service. In order to resolve these issues, having an autonomous behavior is required to the control system of each car in MCE system, so that the learning automaton, as the solutions for this requirement, is supposed to be appropriate for the simple traffic control. First, we assign a stochastic automaton (SA) to each car control system. Then, each SA varies its stochastic behavior distributions for adapting to environment in which its policy is evaluated with each passenger waiting times. That is LA which learns the environment autonomously. Using the LA based control technique, the MCE operation efficiency is evaluated through simulation experiments. Results show the technique enables reducing waiting times efficiently, and we confirm the system can adapt to the dynamic environment.
In the field such as various electric power compensator and ac motor drives, large capacity and high-performance converter are wished to be put into practical applications, with development of various technologies. For these converters, since the upper limit of the switching frequency is low and capacity of device is insufficient, method of connecting the device in series and parallel would be effective. From such reasons, for improving the harmonic characteristics, various multi-level inverters have been reported, in which it is necessary to provide some dc power supplies connected in series that is disadvantage for this inverter. We propose a simple dc-dc converter for adjusting power supply voltage of this inverter. The system is very easy to use because the conventional circuit control techniques can be applied without difficulty. By means of this dc-dc converter circuit, the voltage of four dc power supplies of five-level inverter can be suitably controlled towards the desired value. The circuit characteristics are discussed by theoretical and simulated procedures. The theoretical results and the experimental ones are agree with each other.
A magnetic characteristic measurement, a motor characteristic forecast, and an experimental evaluation of various powder magnetic cores were performed aiming at a fixed quantity grasp when the powder magnetic core was applied to the motor core as the magnetic material. The manufacturing conditions were changed, and magnetic characteristic compares a direct current magnetization characteristic and an iron disadvantageous characteristic with the silicon steel board for a different powder magnetic core. Therefore, though some permeabilities are low, characteristics almost equal to those of a silicon steel board were obtained in the maximum saturation magnetic induction, which confirms that the powder magnetic core in disadvantageous iron in a certain frequency domain, and to confirm disadvantageous iron lowers. Moreover, it has been shown to obtain characteristics almost equal to the silicon steel board when compared in terms of motor efficiency, though some disadvantageous iron increases since the effect when applying to the motor is verified the silicon steel board and the comparison evaluation for the surface type permanent magnet motor.
A single-phase voltage-quadrupler rectifier using a single active power device is presented. This is based on the combination of a half-bridge rectifier and the circuits operated in the switching states for pumping action to pump twice the peak supply voltage onto each of the output capacitors. The experimental prototype employing an insulated-gate bipolar transistor and a controller for output voltage regulation is implemented to investigate the operation. The experimental results confirm that the input current can almost be waveshaped sinusoidally with a near-unity power factor under the output voltage quadruplication.
This paper newly investigates structure and design of high order controller for first order plants that are often encountered in industry applications dealing with mechanical or electrical systems. The proposed structure of the high order controller is characterized by its numerator having full degrees of design freedom. Generally speaking, as order of the controller increases, its design guarantying closed loop stability becomes complicated and difficult. However, the proposed design method is analytical, simple and can assign arbitrary loop stability to the closed systems.
In this paper, an anti-windup compensation method of I-P control system is proposed. The technique is that tracking error signal is modified in the same sampling time so that it may not saturate control input using the equivalent saturation value of integral controller's output. By this technique, prevention of both the overshoot increase due to the wide-banding and the windup phenomenon caused from the saturation of the control input become possible. The effectiveness of the proposed method is verified through the experimental results for position control of a precision stage.