The authors have reported a novel iron loss calculation method based on a loss-map of the magnetic materials. A distinctive feature of this method is that the iron loss on the inductors can easily be calculated in many kinds of converters. In this paper, a novel iron loss calculation method of the ac filter inductor on the PWM inverter by using the loss-map is described. This method enables to calculate the iron loss due to the dynamic minor loops by using the loss map and executing the easy circuit-simulation. The relation between the control method for the PWM inverter and the iron loss is discussed. Finally, the effectiveness of this method is verified through 500W experimental set-up.
This paper presents the characteristics of diode rectifier circuits for the three-phase rectangular-waveform distribution system. Both the amplitude and the rms value of the line current in the proposed rectangular-waveform distribution system can be reduced to √3/2 of those in the conventional sinusoidal-waveform distribution system under the same dc output voltage of the rectifier circuit. From the analysis of the diode rectifier circuit in steady state, the design method of the input inductance and the output capacitance are derived. Furthermore, the commutation capacitors to improve the input total power factor of the diode rectifier circuit are proposed. In order to verify the effectiveness of the proposed methods, the experimental characteristics of the rectifier circuits are shown.
This paper discusses the development of a new type IH cooking heater that uses the double-coil. Adoption of double-coil is the main point of this new IH cooking heater. Current whose phase differs 180 degrees with each other is supplied to a pair of this double-coil. As the result, high frequency—2 times that of supplying current frequency—eddy current flows in the metal load. Using this new technique mentioned above, heating the non-magnetic metals that had been difficult to heat became possible. In this paper, heating characteristics of developed method is made clear. As a conclusion, we report the fact that it has been made possible to heating the non-magnetic metals.
This paper describes an auxiliary power supply system of railways (SIV) for 1500-Vdc power line substituting series connection of 1.2-kV rated standard IGBTs as a switching device for 3.3-kV rated IGBTs. The SIV is allowed to operate up to 5-kHz carrier frequency due to considerable small losses of the IGBTs. Voltages across the series connected IGBTs are balanced by magnetically coupling all the gate lines using a simple two-winding transformer without any snubber circuits. In order to investigate advantages of the SIV operated at higher carrier frequencies, a 150-kVA rated SIV system was tested under 1260-Hz and 4980-Hz carrier frequency conditions, and these performances were compared. The results verifies that making the carrier frequency high can play an important role to realize high performances concerning suppression of an undesired sound from the filter reactor, decrease of the filter size, and improvement of the control response to output voltage with any sudden change of load.
This paper proposes the design method of adaptive rotor flux observer gain to improve stability at low speed and regenerating mode. The method is based on the stability analysis. The stability analysis utilizes the linearized model considering all systems including each control loop. Therefore the proposed method considers the effects of motor constants and control circuit constants. The stability analysis using the transfer function for rotor speed considers the arrangement of pole and zero and the steady state error. The rotor flux observer gain which improves the stability for each operating condition is clarified. Also this paper proposes the real time tuning method of observer gain. The validity of the proposed method is confirmed on the simulation using Matlab Simulink and the experiment.
We developed a battery protection IC integrating a low specific on-resistance bi-directional trench lateral power MOSFET (BTLPM). In the bi-directional switches, two MOSFETs share a drain region and there is neither drain contact nor drain metal wire. The developed bi-directional switches have a breakdown voltage of 23V and a specific on-resistance of 6.8mΩmm2 per one side MOSFET. Wafer-level Chip Size Package (W-CSP) is utilized, and the chip mounting area can be reduced to 3mm2, which is less than one-third of conventional multi-chip system. Parasitic wire resistance is also reduced to 5.3mΩ, which is about one-seventh of that of conventional package without thick copper layer.
The channel mobility in the SiC MOSFET degrades on the rough surface of the p-well formed by ion implantation. Recently, we have developed a double-epitaxial MOSFET (DEMOSFET), in which the p-well comprises stacked two epitaxially grown p-type layers and n-type region between the p-wells is formed by ion implantation. This device exhibited a low on-resistance of 8.5mΩcm2 with a blocking voltage of 600V. In this study, to further improve the performance, we newly developed a device structure named implantation and epitaxial MOSFET (IEMOSFET). In this device, the p-well is formed by selective high-concentration p+ implantation and following low-concentration p-epitaxial growth. Fabricated IEMOSFET with a buried channel exhibited superior characteristics than DEMOSFET. The extremely low specific on-resistance of 4.3mΩcm2 was achieved with a blocking voltage of 1100V.
The ozone composing mechanism had not been examined experimentally in both the electrical discharge stage and the ozone composing stage separately. Therefore it was impossible to determine exactly how ozone was composed and also impossible to get high yield efficiency in producing ozone. In examining the ozone composing mechanism we conducted four experiments. In part 1, we explain initial two experiments. In the first experiment, we found that the concentration of ozone increased when nitrogen was added to a gas-mixing chamber. We therefore determined that, for ozone to be composed, a third element was required when an oxygen molecule and an oxygen atom collided. Our second experiment confirmed that this same phenomenon could be observed on the surface of a copper anode. A computer calculation confirmed this.
In our third experiment, we changed the density of nitrogen through the addition of heat energy to the anode. A computer simulation confirmed the same phenomenon. Then the copper anode was replaced with an antimony anode. We found that antimony worked better than nitrogen as a third element. Finally, in the fourth experiment, we used an industrial ozone generator including ceramic dielectrics and a titanium expanded metal electrode. A decrease in the temperature of the cooling water led to a proportional increase in ozone. It follows the formula of van't Hoff. After spattering the surface of the electrodes with argon gas and supplying the ozone generator with 99% oxygen, we were able to produce ozone which was more than 20% higher in concentration than primary state ozone under the same conditions. The ozone generator produced ozone in high yield efficiency due to the optimum density of a third element like nitrogen on the surface of the electrodes. Antimony works better than nitrogen does as a third element.
This paper analyzes shaft voltage and bearing current in a nongrounded motor driven by a voltage-source PWM inverter. First, the shaft voltage of the nongrounded motor is measured. The experimental results indicate that a bearing current, which can not be explained by the conventional theory, exists, and that the bearing current may shorten the life of the motor bearing. To investigate the mechanism, some experiments and parameter measurements are done, and simulation models are built. As a result, it is shown that this issue is caused by unbalance in the inductance and stray capacitance of the motor windings and these resonant phenomena.
This paper presents an adaptive mesh generation with parameterized learning. The present method does not need to perform iterative processes of field analysis in contrast with the conventional adaptive meshing methods. The present method evaluates mesh qualities for each element by means of evaluation function, which is weighted linear combination of shape and area of elements, distance from material corners and so on. The element which has the worst value of the evaluation function is divided into a few elements according to its shape, and this procedure is repeated until the prescribed number of elements is obtained. By using the simple Genetic Algorithm (sGA), the weighting coefficients are optimized through learning with example models such that the resultant mesh has the lowest numerical error. The good mesh can be obtained without time-consuming computation, since the weight values for the mesh features are learned by the sGA. The present method would allow us to realize effective design and development of electromagnetic machine and devices.
This paper presents an identification technique of parameters of a high frequency equivalent circuit of permanent magnet synchronous motors (PMSM) driven by a PWM inverter. The high frequency oscillatory currents such as leakage current to the motor frame (common-mode current) and high frequency oscillatory line current (normal-mode current), are generated by switching instants of inverter transistors. The parameters of the high frequency equivalent circuit of PMSM which can simulate the oscillating current are identified by means of genetic algorithm. It is shown that the high frequency equivalent circuit with identified parameters can generate the oscillating current by some simulation results.
This paper proposes a new suppression method of magnetic-flux deviation in series transformers used in a dynamic voltage restorer. A dc flux as well as an ac flux appears in the series transformers at the beginning of voltage-sag compensation. Since an amount of dc flux depends on a phase angle of the source voltage at the beginning of compensation, the sum of an ac flux and a dc flux may reach twice the rated flux. Therefore, the cross section of a series-transformer core should be designed twice as large as that of a generally-designed transformer, in order to avoid flux saturation. The proposed method to eliminate dc flux from the series transformer makes the compensating voltage zero for a short duration. As a result, only an ac flux appears in the series transformer, thus allowing us to use a generally-designed transformer. Experimental results obtained from a 200-V, 5-kW laboratory system are shown to verify the viability of the proposed method.
This paper describes a fluid model based path planning of mobile robot. In the previous research, the authors have already proposed TBSA (Time Based Spline Approach) for smooth motion of industrial robots(1). The TBSA is a powerful method in industrial applications, but the future position and velocity commands must be known to use it. In the general applications of repeat motion, this assumption is acceptable. In the path planning of mobile robot, however, the future position and velocity commands are unknown. To address the above issue, a strategy to generate the path of mobile robot based on fluid model is proposed in this paper. The combination of the TBSA and the generated path by fluid model brings a smooth motion of mobile robots.
Recently, much importance has been attached to the environmental problem. The content of two directives to better control the management of waste electronic equipment was approved. The two directives are the Waste from Electrical and Electronic Equipment (WEEE) and the Restriction of Hazardous Substances (RoHS). These set phase-out dates for the use of lead materials contained in electronic products. Increasingly, attention is focusing on the potential use of Pb-free soldering in electronics manufacturing. It should be noted that many of the current solding irons are not suitable for Pb-free technology, due to the inferior wetting ability of Pb-free alloys compared with SnPb solder pastes. This paper presents a Pb-free soldering iron temperature controller using an embedded micro-processor with a low memory capacity.
This paper proposes a new voltage-balancing circuit for the split dc voltages in a diode-clamped five-level inverter. The proposed circuit is based on a resonant switched-capacitor converter (RSCC), which consists of two half-bridge inverters, a resonant inductor and a resonant capacitor. A new phase-shift control of the RSCC is proposed to improve voltage balancing performance. Theoretical analysis reveals the rating of the RSCC and stored energy in the resonant inductor. Experimental results confirm the reduction of the inductor to one tenth in volume as compared to a conventional voltage-balancing circuit based on buck-boost topology. Moreover, the proposed phase-shift control has demonstrated that it is possible to eliminate the voltage deviation between the dc capacitors.
This paper presents an optimal control method of dc-dc converters. The method is based on hybrid dynamical system theory. Specifically, the input of the considered system is confined to discrete value whereas the output to be controlled is continuous value. The system is modeled as a mixed logical dynamical system. Then, the optimal control law is obtained by means of model predictive control. The effectiveness of the proposed approach is illustrated through some numerical simulations.
To obtain higher DC output voltage, a single-phase boost rectifier adding a capacitor for pumping action in DC circuit is studied. This gives two-stage boost operation by means of inductive and capacitive energy storage/transfer mechanisms under the high-frequency switching. The experimental prototype, employing an insulated-gate bipolar transistor as an active power switching device and a PI 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 by the current-mode control.