Realization of High-Stability Flat-Top Pulsed Magnetic Fields by a Bypass Circuit of IGBTs in the Active Region

摘要

A high-stability flat-top pulsed magnetic field (FTPMF) is strongly needed for some scientific studies, such as nuclear magnetic resonance and specific heat measurement. This paper presents a new linear flat-top regulation bypass circuit to generate a high-stability FTPMF based on a battery bank power supply. The bypass circuit consists of insulated-gate bipolar transistors (IGBTs) in parallel that operate in the active region and are free of switch ripples. To achieve precise control of the IGBT current, the influence of the Miller effect and the nonlinearity of the IGBTs transfer characteristic are studied in detail. Then, a dual-feedback loop is designed and analyzed. A prototype consisting of a 1000V30kA battery bank and a bypass circuit of 1700V3600A IGBTs is developed. An FTPMF with a fieldduration of 23.370T100ms and a stability of 64.2ppm has been achieved.