The purpose of this paper is to improve power conversion efficiency of three-phase voltage-source type soft-switching inverter with a single auxiliary resonant DC link (ARDCL) snubber. In the first place, the operating principle of an ARDCL snubber discussed here is described. In the second place, this paper proposes an effective generation scheme of zero voltage space vector of three-phase soft-switching inverter using IGBTs that can reduce power losses in the ARDCL snubber treated here. In particular, a zero voltage holding interval in the DC busline of this soft switching inverter is to be regulated due to, the generation scheme of zero voltage space vector. In the third place, the maximum modulation depth Mmax under the condition of compensation of space voltage space vector can be improved by using a new zero voltage space vector generation scheme. Finally, the feasible experimental results to confirm the operating characteristics such as power conversion efficiency, THD and RMS value of output voltage for three-phase voltage-source type soft-switching inverter using IGBTs is concretely implemented and evaluated from a practical point of view.
In a large-scale inverter system, a DC circuit connects the rectifier and the inverter. A harmonic resonance phenomenon is often induced by the DC capacitor to stabilize the voltage and the inductance of distribution wires. When the harmonic resonance is induced, the DC circuit is interfered with by the magnified harmonic component of the inverter input current. Therefore, it is necessary to analyze the harmonic resonance phenomenon and the inverter input current. To absorb the harmonic current and voltage, the DC capacitor is connected to the rectifier and the inverter sides in the DC circuit. Moreover, to restrain the voltage fluctuation by sudden changes in the load, it is necessary to connect more DC capacitors. We clarified the relation between the harmonic resonance phenomenon and the capacitor distribution on both sides, examined the input harmonic current of the multiple stages PWM inverter that is used to drive the LSM and has different configurations depending on train speed, and confirmed the above by simulation.
This paper proposes a method to search a target image area that has arbitrary location and inclination in an objective image. The method uses the curvature of an edge pixel that is an invariant characteristic to location and inclination of a target image area. The curvature of an edge pixel and the distance between the central pixel and the edge pixel are measured in a circular image area. The stored value in the two-dimensional space that is spread by the curvature and the distance is incremented. This process is repeated about all edge pixels in the circular image area. The matching is executed between the two-dimensional spaces that are generated by the circular template image and generated by a circular image area in an objective image. The experimental results show that the recognition rate of the target image areas recorded 97.8% about four kinds of images. The averaged processing time to search the target image areas was 20.4 seconds.
With recent remarkable development of power electronic technology, a Switched Reluctance Motor (SRM) has been widely studied for practical use. There still remain some problems to improve, e.g. relatively high torque ripples, electromagnetic noise and iron loss. We have concentrated on iron loss and discussed simple method to estimate it. The analysis of iron loss enables us to know not only total loss but also its distribution, therefore it would be possible to calculate the temperature analysis. A proposed method is based on 2D static Finite Element Analysis (FEA) and loss data given by open circuit test. Eddy current loss is evaluated by the frequency analysis of flux density waveforms using Fourier transform, while hysteresis loss is evaluated by the classification of the waveforms in each position of the magnetic circuit. The total loss and loss distribution are obtained. The validity of this method is verified in comparison with measured values in two types of SRM with different material property.
This paper proposes a transformerless shunt hybrid filter for harmonic compensation of a three-phase six-pulse diode rectifier, where the ac line-to-line voltage is 3.3kV or 6.6kV. The hybrid filter consists of a single tuned LC filter per phase and an active filter with a dc capacitor voltage as low as 300V or 600V. The two filters are directly connected in series with each other without any transformer. The passive filter absorbs harmonic currents produced by the rectifier, whereas the active filter improves the filtering characteristics of the passive filter. The required rating of the active filter is much smaller than that of a conventional shunt active filter used alone. In addition, no additional switching-ripple filter is required for the active filter, because the LC filter acts not only as a tuned LC filter around the 7th-harmonic frequency but also as a switching-ripple filter around 10kHz. A feedforward control scheme is also proposed to improve the active filter performance. Experimental results obtained from a 200-V, 5-kW laboratory system and simulation results of a 3.3-kV, 300-kW system confirm the validity and effectiveness of the system. The hybrid filter gives satisfactory compensation performance, thus allowing us to put it into practical use.
In resent years, a sinusoidal excitation equipment, that is, a two-phase induction motors fed by AC and DC voltage-source have been employed in angular accelerating calibration of the angular accelerometer, the measuring device of moment of inertia, cleaning and polishing device etc. as a excitation equipment. Generally, the excitation equipments are required to have larger alternating torque. Previously we have derived the practical equation to calculate the alternating torque of excitation equipments. In this paper, at first, for the sinusoidal excitation equipments that is, two-phase induction motor fed by AC and DC voltage-source, the relation among the equipment circuit parameters and an alternating torque characteristics are investigated numerically. And, the influence of equivalent circuit parameters on the alternating torque characteristics and it's tendency are clarified. Secondly, a guideline for the excitation equipment design that can be generate larger alternating torque are presented by using the equivalent circuit parameters. Lastly, in order to verify the validity of our new strategy, the trial excitation equipments which is designed by the various redesign condition has been compared with the previous excitation equipments.
This paper presents an efficient high-frequency soft switching PWM boost chopper controlled DC-DC power converter with a single auxiliary passive resonant snubber, which is more suitable and acceptable for high power applications. The proposed boost chopper type power converter capable of operating under soft commutation principles of series inductor-assisted Zero Current Soft Switching (ZCS) at turn-on transition and parallel capacitor-assisted Zero Voltage Soft Switching (ZVS) at turn-off transition is more effective to reduce switching power losses of an active power switch and EMI noises relating to switching surges on the basis of the DC load side power recovery feedback power processing. The operating principle of soft switching boost chopper type DC-DC power converter treated here is described and its performance evaluations are discussed and evaluated through simulation and experimental set-up for 5kW power rating specification. The validity and effectiveness of this soft switching PWM boost type power converter using IGBTs are proved as compared with some performances of a hard switching boost chopper type power converter from an experimental point of view. The modified soft switching converter topologies using a single passive resonant snubber are demonstrated in here.
This paper proposes a new GTO model for drive circuit design. The proposed model is easy to use for GTO consumers, because the model parameters are easily obtained from the manufacturer's data-sheet and some simple measurements. In this paper, the authors demonstrated the model by comparison of simulation and experimental result. These results show good performance of the model for designing drive circuit.