Analysis and eliminating method for undesirable setting of magnetic amplifier on single-ended DC-to-DC converter

• Published in: Electronics & communications in Japan. Part 2, Electronics Vol. 71; no. 8; pp. 81 - 94
• Main Authors: Onda, Kenichi, Abe, Koojin, Matsuda, Yasuo, Amano, Hisao
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 1988
• ISSN: 8756-663X; 1520-6432
• DOI: 10.1002/ecjb.4420710809

For a single‐ended dc‐to‐dc converter using a magnetic amplifier, an undesirable setting of the magnetic amplifier during the off‐period is analyzed. It is found that the C and R snubbers are installed on the main switch and on the rectifying diode on the secondary wiring of the transformer discharge during the off‐period of the main switch, and then this discharge current undesirably sets the magnetic amplifier. The undesirable setting quantity increases if a transformer with a smaller magnetization inductance or a saturable reactor with a smaller coercivity is used. Hence, the effect is more pronounced in a converter operated at a higher frequency. The undesirable setting is larger in a converter with a lower output voltage. From these results, a new circuit is proposed in which the coercivity of the saturable reactor can be increased effectively by installation of a winding for flowing the reset current in a magnetic amplifier. It is confirmed that this system can reduce the undesirable setting.