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