On the constant output voltage control of inverter using the asymmetrical magnetization of its transformer

In a transformer for static converter, interrupted currents flow through its DC windings. The DC components of these current bias magnetomotive forces in respective magnetic cores of the transformer. Thus the iron cores are asymmetrically magnetized. To avoid various abnormal phenomena associated with this asymmetrical magnetization, we often use the so-called Greatz connection. However, even in this case a transformer is sometimes asymmetrically magnetized due to unbalance of control angles and variations of overlapping angles due to ripples of DC cur. rent. The performance of static inverter is greatly affected by the extent of asymmetrical magnetization. Conversely, this phenomenon can be utilized to improved the circuit characteristics and to facilitate the control of output voltage. This paper discusses the constitution of output voltage control system using the asymmetrical magnetization of inverter transformer and makes clear of its excellent characteristics in comparison with lagging angle control of rectifier generally used in these days. As the results of comperation, it has been pointed out that：(1)the respollse speed of asymmetrical magnetization method is higher than that of lagging angle control method；(2)the output voltage of asymmetrical magnetization method can easily be adjusted over the range of 10％, but that of lagging angle control method is adjustable from zero to its rated values, (3)the structure of asymmetrical magnetization control device is simpler than that of lagging angle control device