Saturation and Short Pulse Response Characteristics of the Fe-Based Amorphous Core With a Small Air Gap

In this paper, saturation and high-frequency pulse response characteristics of the Fe-based amorphous core with a small air gap are studied in detail by theoretical analysis and experiments. After a 0.32-mm air gap was cut through the longitudinal cross section of the amorphous core, test results showed that the relative permeability of the amorphous core only had small changes. Therefore, mechanical processing jobs can be done on the amorphous core made of curled fragile thin tapes. In the charge experiment, the maximum saturation voltage of a 1:10 transformer based on the air-gapped core increased by 1.33 times in contrast to that of the closed-core situation, which basically corresponded to the theoretical calculation (1.6 times). The small air gap obviously improved the saturation characteristics of the amorphous core but decreased the coupling coefficient and step-up ratio of the 1:10 transformer. Experimental results of another 3:3 transformer based on the air-gapped core proved that the air gap had great effects on the high-frequency response characteristics of core-type transformers. The loss ratio of the response voltage signal of the air-gapped-core transformer increased by about 30% in contrast to that of the closed-core situation. The air gap had small effects on the front-edge response to square pulses.