Characterization of Operating Overvoltage of No-Load Regulators

When circuit breakers in particle accelerators interrupt inductive loads, the resulting transient overvoltages propagate through conduction or radiation, posing significant electromagnetic compatibility (EMC) challenges for sensitive electronic equipment. Existing EMC standard test waveforms substantially deviate from actual overvoltage characteristics, failing to provide theoretical foundations for practical filter protection circuit design. Addressing these issues, this study systematically investigates no-load voltage regulator operations, focusing on the mechanisms, measurement, and modeling of switching overvoltages. Key contributions include: Deriving system equations to quantify operational parameters influencing overvoltage magnitude; Establishing an experimental platform to capture representative overvoltage waveforms; Developing lumped-parameter models in LTspice to analyze extreme overvoltage scenarios; Constructing a spike overvoltage mathematical model through Differential Evolution (DE) algorithm optimization based on the IEC 61000-4-5 voltage surge standard. The model demonstrates strong consistency with experimental measurements (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$R^{2}=0.95$</tex>), providing critical data support for designing overvoltage generators and filter protection circuits.