Basic Characteristics of Squarewave Irwerter Circuit with Series R-L Load

In this paper, the steady state operations of the squarewave inverter circuit with a series R-L load are discussed. The circuit consists of transistors and feedback diodes. The basic equation is derived from its equivalent circuit. Solving the basic equation with steady state conditions, the instaneous value of the load current i is derived. The period t(2) for which the current flows from the supply to the load and the period t(l) for which the current feedbacks through diodes from the load to the supply are calculated from (i), and the ratio of t(l) to t(2) is illustrated using power factor of fundamental wave, pf, as a variable. The ratios of transistor mean current I(tr), diode mean current I(D), supply mean current I(s) to the load current I are illustrated using pf as a variable, too. In result, each current ratios to I is shown in simple expressione. The load current can be calculated simply using the coefficient reading off the figure. In addition, it becomes clear from the figure that the load current is scarcely influenced by the harmonic voltage in less than 0.8 of pf. The ratio t(2)/(t(1)+t(2)) calculated in squarewave voltage, shows the limit of pulse width control whose out put voltage is the squarewave

A Driving Method of a Spuare Waveform Inverter Circuit Using Power Transistors

In recent years, the development of a high power transistor element is proceeding. A high power inverter circuit using power transistors are finding a good number of applications in induction heating and melting. Turn off time of power transistors occupies 5-lOμs of switching characteristics. A driving method to give base inputs for a half period is widely used for a inverter circuit. But this method has the following defects, the short-circuit current flows through two transistors because the other pair transistors turn on before one pair transistors turn off. So the switching loss is increased, the maximum output and the efficiency are decreased. In this paper, a driving method to give base inputs for the less period as compared with a half period is discussed. Using this method, the foregoing defects is lost and the driving frequency is able to become higher. In addition, it become clear that the square waveform output is given using this method in the case of R-L load

On the Speed Control of a Three Phase Squirrel Cage Induction Motor Controlled by a Variable Frequency Three Phase Thyristor Inverter

As one of the wide application of thyristor circuits, the inverter has a promising future and has been investigated vigorously. On the speed control of a squirrel cage induction motor by using a variable frequency thyristor inverter, although few papers have been presented, there seems to be many problems to be solved imminently. In this paper, the stability of performance of a thyristor inverter on this theme has been confirmed and some particular points with relation to practical use also have been discussed

Analysis and Design of Parallel Inverter Circuit with Parallel Inductive Load

In this paper, the parallel inverter circuit with the load consisted of resistive load and constant reactive load in parallel, is analyzed taking into acourlt the d-c source reactance. The circuit has a good voltage regulation for the variation of resistive load current, except the vicinity of no load. The design method in using the results of analysis is also discussed

Analysis of the A-C Voltage Control Circuit with ParallelConnection of SCR and Reactor

The a-c voltage control circuit, composed of parallel connection of a SCR and a reactor, gives the similar performance as the control circuit of a back to back SCR pair. However, the control characteristics of this circuit is affected by magnetizing characteristics of reactor. In this paper, the circuit with the resistive load has been analyzed by using the approximated models of hysteresis loop of core materials, where the SCR's forward voltage drop is taken into account. The results of the analysis have revealed the facts as follows, I) The control characteristics of the a-c voltage in average value is independent on the magnetizing characteristics of reactors except in the vicinity of minimum output point. But, in effective value, it is not valid. 2) A SCR's forward voltage drop results in the reduction of not only SCR's current but also reactor's current. 3) The a-c output current does not include the d-c component, if the winding resistance of the reactor is negligible

Measured Dissipated-Energy in Switching-off by Electric Contacts

The measurement of the dissipated energy in switching-off has been attempted to make clear the function of spark on electric contacts, which may unfortunately cause the combustible gas, such as propane gas etc, to catch fire and result in fire accidents. By utilizing the "Memoriscope" has been the meaurement carried out and the feature of this method is to provide the information on not only the amount of dissipated energy involved in one action but also on the trace of its instantaneous power which can affect catching fire delicately. Presented in this paper are the discussion of this measuring method and the measured results which are obtained experimentally in order to investigate the dependence of the energy dissipation on variety of contacts, contacts' deterioration and circuit arrangements

Photoinduced C70 radical anions in polymer:fullerene blends

Photoinduced polarons in solid films of polymer-fullerene blends were studied by photoluminescence (PL), photoinduced absorption (PIA) and electron spin resonance (ESR). The donor materials used were P3HT and MEH-PPV. As acceptors we employed PC60BM as reference and various soluble C70-derivates: PC70BM, two different diphenylmethano-[70]fullerene oligoether (C70-DPM-OE) and two dimers, C70-C70 and C60-C70. Blend films containing C70 revealed characteristic spectroscopic signatures not seen with C60. Light-induced ESR showed signals at g\geq2.005, assigned to an electron localized on the C70 cage. The formation of C70 radical anions also leads to a subgap PIA band at 0.92 eV, hidden in the spectra of C70-based P3HT and MEH-PPV blends, which allows for more exact studies of charge separated states in conjugated polymer:C70 blends.Comment: 3 pages, 4 figures, accepted for PSS RR