An Adaptive Pulse‐Width Driving Method for Ultra‐Fast Mechanical Switches in DC Interruption Applications

ABSTRACT

Fast mechanical switches (FMSs) are critical components for fault current interruption in DC circuit breakers (DCCB). The electromagnetic repulsion mechanism (ERM) is essential for achieving the ultra‐fast operation required in high‐voltage DC interruption applications. However, conventional driving circuits for ERMs, which typically rely on thyristor‐based single‐discharge schemes, suffer from limited controllability and adaptability to variations in mechanical characteristics, often necessitating laborious factory calibration and compromising system reliability. To address these limitations, this paper proposes a fully controlled driving circuit for ERMs based on insulated gate bipolar transistors (IGBTs). The proposed circuit enables precise pulse width modulation (PWM) of the driving current, allowing the impulse of the electromagnetic repulsive force to be regulated between successive switching operations. Furthermore, an intelligent control algorithm integrating an adaptive secant method is developed to realise off‐line iterative learning‐based speed optimisation and adaptive correction, improving operational consistency and short‐term repeatability. The performance of the proposed method is experimentally validated on a prototype FMS integrated into a 2 kV/2.5 kA DC circuit breaker test platform. Results demonstrate precise speed control (steady‐state error within 1% at 3 m/s), improved dynamic response (recovery within five iterations under disturbance) and reliable interruption performance, confirming the effectiveness and practical applicability of the proposed approach for advanced DC interruption systems.