Drum-type washer/dryers are becoming more common in Japan, but the vibration created by unequally distributed clothes is a significant problem in this type of machine. We have developed a vibration control that prevents this imbalance by re-arranging the balancer fluid on the opposite side of the heavier distribution when there is unequal distribution. The drum, which has a large inertia, must be decelerated rapidly to enable the balancer fluid to shift. When a permanent magnetic synchronous motor is decelerated using an inverter, the machine's energy is converted into electrical energy, which regenerates the power supply. A control method has been developed that adjusts the input power of the motor to zero, thereby eliminating the need for a discharge circuit. However, it is not easy to achieve this method with an inexpensive microcomputer. In this paper, a practical braking method in which energy does not regenerate the power supply is examined. First, a simple method in which non-regenerative braking is possible with low input power is proposed, even though the input power is not zero. The effectiveness of this non-regenerative deceleration control is verified by theoretical numerical analysis and by an experiment. The borderline of the voltage vector for the non-generative braking is affected by dead time, and the experimental results differ from the theoretically calculated results. However, it is experimentally confirmed that the proposed non-regenerative deceleration control can be achieved by correcting the impressed voltage vector based on experimental results. Finally, this control is applied to the vibration control of the drum-type washer/dryer, and it is confirmed that the balancer fluid moves as designed.
The railway signaling system should be optimized in accordance with requirements such as maintainability, cost effectiveness, safety, reliability and availability. That optimization, however, tends not to be sufficient necessarily due to its complexities and existing system design methods in the railway signaling field. To resolve this insufficiency, therefore, we propose top-down requirement analysis and integrated life cycle cost evaluation as a new method of the system design. In our method, various indexes of requirement are to be converted into the life cycle cost to enable us to evaluate offspring of various system designs from the appropriate viewpoint. To improve economics of construction for the Shinkansen network expansion, we intend to apply the method of system design of the Shinkansen signaling and to prove that it is effective in all of railway signaling system areas including existing lines. There is no precedent for this kind of methodology in the area of Japanese railway signaling systems. This paper introduces the proposed method with procedures of the requirement analysis and results of the integrated life cycle cost evaluation.
A magnetically levitated (MAGLEV) vehicle using electro-magnets and iron rails generates lateral guiding force naturally by controlling levitation force to maintain the air gaps between the magnets and the iron rails. A MAGLEV system without guide magnets offers simple design and cost advantages. But such a system has little lateral damping force. In order to improve damping characteristics, an experimental apparatus using salient-pole type magnets and laminated iron rails was made. The iron cores were placed in two rows. The levitation coils surrounded both of the magnet iron cores and the damping coils surrounded every magnet cores separately. The damping coils were excited by currents proportional to the lateral displacement velocity. According to a step response experiment, the lateral motion dissipated after a cycle or two of the swing. The self-inductance of the levitation coil of the magnet almost unchanged against variation of the lateral displacement. The influence of damping current on the levitation was very small. In this paper electromagnetic characteristics of the levitation system are shown.
An intelligent wheelchair for adaptation to unknown and/or unstructured environment is developed in this paper. In the motion control under open environment, it is necessary for a robot to adapt to interference from other systems and unknown environment. Since both of the human force and the external force from the environment are applied to a robot as a disturbance, it is difficult for a robot to decompose them into each mode. In order to solve the above problem, a novel force sensing method named “Environment Quarrier" is proposed in this paper. Two same types of robots are required and they are controlled in the same position, velocity and acceleration by bilateral control. One robot is in contact motion and the other is unconstrained. The gravity and the friction effects are identified by the disturbance observer. The purity of external force is obtained by subtracting the disturbance torque in the unconstrained robot from the constrained one. The proposed method is applied for a power-assist wheelchair. An operationality of a human and adaptability to the environment are improved. Sensor-less force control based on the environment quarrier is one of the fundamental techniques for evolution of human-cooperative robots. The experimental results show viability of the proposed method.
This paper presents characteristics comparison of a high-frequency multi-level inverter connected with small capacity filter inverters. In general, PWM inverters require a low-pass filter in order to reduce switching harmonics. However, in the high-frequency systems such as class D power amplifiers, the cut-off frequency of the low-pass filter must set at high frequency. Thus, harmonic distortion of the output voltage harmfully enlarges. Increasing the number of output voltage levels is effective to reduce the harmonic distortion of the output voltage and the low-pass filter size. The proposed systems consist of a 5-level inverter and several cascade-connected low-voltage full bridge inverters without any external DC power sources for filtering the output voltage. The 5-level inverter generates a stepwise waveform with 5-level voltage, and the low voltage filter inverter superimposes harmonic components to compensate for the voltage waveform distortion. Therefore, the proposed system can reduce its total switching loss and can increase the number of the output voltage levels. In this paper, effectiveness of the proposed systems is verified through several experiments.
This paper proposes a new inrush current suppressor using a series-connected small-rated PWM converter for a transformer. The PWM converter is directly connected in series between the source and transformer without a matching transformer. The inrush phenomena of the matching transformer, thus, can be avoided. The control gain and required-ratings of the series-connected small-rated PWM converter is discussed in detail. The capacity of the dc capacitor of the PWM converter is also discussed considering the active power flows into the PWM converter. The PSCAD/EMTDC is used to verify the validity of the proposed inrush current suppressor. A prototype experimental model is constructed and tested. The experimental results demonstrate that the proposed suppressor can perfectly overcome the inrush phenomena of transformers.
Electronic apparatus, such as a computer, are a capacitor input type rectifier load for a power supply. The rectifier load causes the fact that a power source voltage waveform is distorted. This paper describes the output voltage characteristic of the single phase PWM inverter applied a discrete-time model following control to the rectifier load. First the rectifier load model of a discrete time system is considered. Next, the discrete- time model following control system used for this load is described. Then, a simulation result and an experimental result are examined. The simulation results is shown that this method has robustness to the load change. The experimental system consists of an inverter controlled by a digital signal processor (DSP) and the rectifier load. The validity of a simulation result is shown by the experiment.
Creation of interlocking charts, which are related to the safety of train operation, requires a complicated logic and a large amount of manpower. This necessitates a computerized support system. We judged that electronic processing of a track diagram was important, in order to systematize. The signal equipment on a track diagram was clearly systematized by the object-oriented analysis. A track diagram network is established with two types of networks, one representing switches and signal devices at specific points on the track and the other representing track circuits and signal devices in specific domains of the track, each representing the routes of actual train operation and those in the position detection units of interlocking devices. The tables drawing function and automatic connection between signal devices through system control are realized by using a commercialized CAD interlocking charts has been developed by applying these techniques.
If friction aspects have an electric current, they have not only the friction and wear but also the wear of the influence of it. Pantographs of trains and so on do slide under it, so the wear progresses are influenced by the electric phenomena strongly. We think these wear act with each other and make far larger wear than single wear. But we haven't made the details of it clear yet. Firstly, we set the brief condition of our apparatus for experiments, and observe the phenomena in these conditions. For it, we use the way of observation, the in-situ observation way, and four friction materials of metals and carbon. So far the wear is classified into some wear types. The adhesive wear shows the nearest wear ratio to the real wear of Pantographs. But the real one is larger than the range of the adhesive wear. And there have to be some causes to show this. We can think that an electric current influences the difference in the wear ratio. Then it is necessary how electricity have influences to them: to find phenomena that occur in wear processes and influence the increase of wear. They are the electric discharge and the fusion of materials. It became obvious the electric discharge and the fusion of metals are two main things under the influence of the electricity. So far as the source of the heat for fusion, the constriction resistance is the biggest one and the heat of friction is far smaller than that of constrictions. It is the phenomena caused by the pass of electricity between two contact members. On the other hand, the electric discharge occurs at the space made between two members, a pin and a block, and it has the electric flow in the air. And this phenomenon makes more unevenness on the surface that causes more electric discharges and fusions. After all the wear from electricity has greater influence than that of adhesion. In future we need to investigate the difference of the total wear volume between the electric discharge and the fusion.
The precision of a few centimeters can be easily obtained in 2drms of the horizontal positions by RTK-GPS positioning, as the range from a user GPS antenna to the satellite is determined by the phase measurement of the carrier waves. Since December 2000, it has been operated experimentally by the network-based system, known as the area correction parameter FKP (flächen-korrectur-parameter of the Geo++ GmbH in Germany) system in Kanto area. Now, the authors tried the network-based RTK-GPS positioning using the data transmission via the cellular phone every second at several fixed points, located inside the reference station network area, simultaneously. They investigated the dependent on the location for the precision of them. 2cm+(base line length)*2ppm cm in 2drms of the horizontal positions and S.D. of altitude measurements are similar to the RTK-GPS positioning. We must improve the network-based RTK-GPS precise positioning in order for it to be used by most people more easily.
In this paper, novel two-degree-of-freedom deadbeat control is proposed for a single-phase inverter. The conventional deadbeat system had too poor stability robustness because of the high-gain feedback controller. On the other hand, the proposed controller can assure the deadbeat command response by the multirate feedforward controller as well as the stability robustness which is guaranteed by the feedback controller with reasonable gain. Although single-rate systems could not guarantee zero tracking error for arbitrary reference signals, the proposed multirate control can achieve perfect tracking at every sampling point. Moreover, the dead-time compensation is introduced to reduce the voltage error. Finally, the simulations and experiments are performed to show the advantages of the proposed method.
In this paper, we investigate the iron loss of interior permanent magnet motors driven by PWM inverters using electromagnetic field analysis. Following 4 methods are applied: (1) Current input finite element method neglecting the carrier harmonics. (2) Voltage input finite element analysis neglecting carrier harmonics. (3) Current input finite element method with the measured armature current waveforms including the carrier harmonics. (4) Voltage input finite element method with the theoretical voltage waveforms of the PWM inverter. The calculated results are compared with the experimental ones. It is clarified that the accuracy of the calculated results are improved by considering the carrier harmonics and that the method (4) can estimate the iron loss of the IPM motor accurately before manufacturing. The variation of the iron loss components due to the driving condition is also clarified.