Control schemes for auxiliary switches of PWM controlled three-phase resonant snubber inverters (RSIs) are proposed. The control schemes proposed in this paper are based on a conventional PWM technique. To avoid zero voltage switching lost conditions, the conventional PWM technique is modified in the proposed schemes. The proposed control schemes are so simple that they are suitable for digital control. In this paper, a CPLD (Complex Programmable Logic Device)-based control IC, which realizes the proposed control schemes, for three-phase auxiliary RSIs is also proposed and implemented. The IC generates gate-signals for main- and auxiliary-devices of the three-phase RSI based on the proposed control schemes. The effectiveness of the proposed control schemes were verified through the experiments. As the results, ZVS (Zero Voltage Switching) turn-on at the main devices was achieved and a smooth sinusoidal output current was obtained by use of the control IC.
This paper presents a single lossless inductive snubber-assisted ZCS-PFM series resonant DC-DC power converter with a high-frequency high-voltage transformer link for industrial-use high power magnetron drive. The current flowing through the active power switches rises gradually at a turned-on transient state with the aid of a single lossless snubber inductor, and ZCS turn-on commutation based on overlapping current can be achieved in wide range pulse frequency modulation control scheme. The high-frequency high-voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high-frequency high-voltage transformer and the magnetizing inductance of the high-frequency high-voltage transformer. As a result, this high-voltage power converter circuit for the magnetron is possible to achieve a complete zero current soft switching under a condition of the broad width gate voltage signals. Furthermore, this high-voltage DC-DC power converter circuit can regulate the output power from zero to full over audible frequency range because of two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view.
The engine essentially consists of a rotor made of temperature sensitive magnetic material and permanent magnets. When an object made of this material has temperature distribution in the magnetic field, the force is generated to the direction from the low temperature side to the high temperature side by magnetic pressure. This paper describes the fundamental performance of the triple magnetic circuit type thermomagnetic engine. The triple magnetic circuit type engine with water-cooling system has been designed. The performance characteristics such as power, resistance loss, and the relation between the temperature of the rotor and the rotation speed has been measured, and compared with the characteristics of single magnetic circuit type engine. The net power is a maximum value of 3.7W at the rotation speed of 0.4rps. The power of the triple magnetic circuit type engine per unit magnetic circuit is about 4 times larger than that of the single magnetic circuit type engine. The resistance loss is of 1.7W at the maximum power point. The total power is of 5.4W. Electromagnetic braking loss is about 25% of the total power. The rate of electromagnetic braking loss to the total power increases with the rotation speed. The disc type rotor with small electromagnetic braking loss has been analyzed. Electromagnetic braking loss of the disc type engine becomes smaller about 95% than that of the cylinder type engine.
The problem of the optimal operating planning for energy supply system is formulated as mixed-integer linear programming (MILP), but, it is too complicated for most untrained operators with little experience to apply the method. This paper proposes an automatic evaluating method of the optimal operating planning for energy supply system in using simple data. The problem can be formulated only from characteristics of equipment, tariff of input energy, and energy demands. The connection of equipment is defined as a matrix, and generated from property data of equipment. The constraints and objective function of the problem are generated from relation-ship data in the matrix and characteristics of equipment. An optimization calculation for the problem is automatically carried out. It is confirmed that any operator can evaluate many alternative configurations of the energy supply systems.
This paper describes a control scheme of fault current limiter by series voltage injection. The current limiter proposed in this study is based on the use of a SMES-based series-connected voltage sag compensator, which has been previously studied by the authors, for controlling fault current caused by short circuit on the load side. An algorithm for fast discriminating between power system voltage sag and load-side short circuit is proposed for the equipment to correctly function either for voltage sag compensation or fault current limiting purpose. Furthermore, a new control strategy based on output voltage phase control of the series compensator is proposed for current limiting with good waveform characteristics and low active power absorption. Experimental results demonstrated the validation of the proposed strategy.
A new approach for real time digital feedback control of PWM inverter is proposed, in which a deadbeat control combined with multirate control method is realized using FGPA (Field Programmable Gate Array) based hardware controller. Adopting the multirate deadbeat control, the sampling frequency of the inverter becomes half of the carrierfrequency, and the tracking error of the output voltage can be decreased. Also the FPGA based control hardware enables to realize almost ideal real time digital feedback controller because of its capability to realize very fast calculation of the control method within a few μ second. Design concept of the FPGA based hardware controller for PWM inverter is proposed, and experiments were carried out. Experimental result shows the ability of the FPGA based hardware controller, the inverter output voltage is coincident with the reference voltage in one sampling period without any compensation. From the view point of UPS applications, the advantages and the disadvantages are discussed through simulations and experiments, the superiority of the proposed control law is verified.
Problem may arise when the drivers are unable to notice or late in noticing emergency vehicles due to the sealing nature of the vehicles, masking by the car audio system or car navigation operation, which poses a threat for common vehicles and emergency vehicles to collide at many crossing. Every minute, problem may arise at every crossing and it is dangerous to wait for the completion of the information infrastructure system, which requires suitable cost and time. Therefore, we propose a system for common vehicles, which detects emergency vehicles using microphone on-vehicle and produce warning information to the driver. In this research, our focus is for “Ambulance", “Fire Truck" and “Police Car". The siren for these vehicles is detected by means of a microphone on-vehicle. This project utilizes two microphones to in order to detect the direction in which incoming emergency vehicles are present. The system, which we propose, must be helpful to response quickly to emergency and rescue activities.
A type of the magnetically levitated railway system with the electro-magnetic suspension system (EMS), which is named HSST system, will be put into revenue service as an urban transport in Nagoya, Japan at the beginning of April 2005. To extend its operational velocity higher than 200km/h for applications in other cities, the design of its EMS system is reexamined for improvement of riding comfort and performances of a train. In order to achieve these objectives, the multipurpose optimization on the basis of the genetic algorithm is applied for the design of EMS-type magnetically levitated vehicle, control parameters of which are optimized both to follow the rail exactly in high-speed and to provide enough riding comfort to passengers. However, the ability to follow sharp irregularities of the rail and to cope with high frequency noises in the gap length control system should be coordinated with riding comfort. The fuzzy logic is introduced into the dynamic control loop and verified to solve the problem. Far better coordination is obtained between the vehicle performances and riding comfort of passengers in high-speed against such various rail conditions. The levitation control with fuzzy logic is shown to be useful for the critical design problem as the high-speed maglev railways.
The capacitor motors (CRMs) are widely used to drive industrial equipment and electric home appliances. Recently, the reduction of the vibration and noise of CRMs has become increasingly important from the standpoint of environmental improvement. However, electromagnetic vibration of CRMs under load has not been analyzed sufficiently. The present paper theoretically and experimentally discusses the causes and characteristics of CRM electromagnetic vibration under load. The primary conclusions are as follows: (1) The general formula for dominant electromagnetic vibration caused by electromagnetic force wave was derived, including the influences not only of a backward magnetic field but also of magnetic saturation. (2) The dominant electromagnetic vibration of CRMs was theoretically attributed to three types of electromagnetic force waves. Two types of electromagnetic force wave are generated by the interaction of two forward magnetic fluxes, such as those of a three-phase squirrel-cage induction motor, and the other type of electromagnetic force wave is generated under the influence of a backward magnetic flux. (3) The characteristics of dominant electromagnetic vibration depending on load and running capacitor were classified theoretically and experimentally into three types based on the characteristics of the electromagnetic force wave and equivalent circuit current. (4) The influences of magnetic saturation in dominant electromagnetic vibration were verified experimentally and their causes were clarified theoretically in relation to electromagnetic force waves.
In this paper, the authors propose a method for detecting fire smoke by using the optical flow. This method is not influenced against the image obtainment environment. About 60,000 fires have occurred every year in Japan. To be most important to the fires is an early period fire fighting. At present, the automatic devices of detectiong fires is needed. The alarms which can detect smoke and heat are utilized to house fires. However, these alarms are not useful for the outside of house such as the incendiary or woodland fire. This method is able to detect such a flame that becomes a fire is the early period. First, the region of the flame in the images obtained from the observation camera is detected. Next, the characteristic quantity that expresses the smoke is extracted. This characteristic is not influenced to the motion such as the cloud, leaf and moving objects. In other words, the only smoke can be detected, from the range which looks like the flame in the image.
Quartz crystal devices have become an essential factor in electronic equipment such as mobile communication equipment or PC. As prices of electronic equipment have lowered, the cost-down of quartz crystal devices has been strongly demanded. To achieve the cost-down of quartz crystal device manufacturing, which uses a complex manufacturing process, the yield of the quartz crystal blank lapping process, which is the preliminary process of the quartz crystal device manufacturing process, must be increased. By introducing the network analyzer to the quartz crystal blank lapping process, we have obtained real time lapping characteristics. By obtaining the new process characteristics in real-time and visualizing them when changing lapping conditions, the network analyzer can now optimize the conditions of the process. In addition, the network analyzer can now measure the optical quartz crystal blank polishing process, which was difficult to measure by using a conventional controller.
The modeling and simulation of hybrid stepping motors using PSpice has been presented. In this letter, we discussed the comparison between the simulation and measured results of the three-phase hybrid stepping motor and confirmed the usefulness of characteristics analysis using PSpice.