Power flexible restart technology for high-speed permanent magnet trains with sensorless control

Abstract The ability to execute rapid restart operations is essential for traction systems in rail transit. However, position sensorless speed restart poses two significant technical challenges: mitigating inrush currents from grid-side excitation and accurately estimating the initial rotor position on the machine side. To address these challenges, this paper proposes a dynamic rapid restart strategy that integrates smooth grid-side excitation and overvoltage suppression with machine-side initial rotor position estimation using fundamental back electromotive force (EMF). This strategy enables fast and flexible power restart on both the grid and machine sides. The efficacy of the proposed approach is validated through both simulation and experimental testing.