Design and Experimental Testing of a Moving Coil Actuator with Compensation Coil

Hydrogen-powered electric aircraft have attracted significant interests aiming to achieve decarbonization targets.Onboard DC electric networks are facing great challenges in DC fault protection requirements.Vacuum interrupters are widely used in low voltage and medium voltage power systems due to being environmentally friendly with low maintenance.In this paper a moving coil actuator with compensation coils for a vacuum interrupter,as part of a hybrid direct current circuit breaker,is designed and experimentally tested.Compensation coils are used to improve operating speed compared with original moving coil actuator.Comparisons between four possible connections of compensation coils and original moving coil actuator are carried out.Experimental results show comparisons between different connections of actuator coils in terms of opening time and coil current with a range of pre-charged capacitor voltages.Dynamic performance of each actuator connection is also compared.The actuator with compensation coils is shown to have a higher current rising rate and achieve faster opening speed,which is a critical requirement for electric aircraft network protection.The parallel connection actuator achieves the highest opening speed within 3.5 ms with capacitor voltage of 50 V.

An online terrain classification framework for legged robots based on acoustic signals

Terrain classification information is of great significance for legged robots to traverse various terrains.Therefore,this communication presents an online terrain classification framework for legged robots,utilizing the acoustic signals produced during locomotion.The Mel-Frequency Cepstral Coefficient(MFCC)feature vectors are extracted from the acoustic data recorded by an on-board microphone.Then the Gaussian mixture models(GMMs)are used to classify the MFCC features into different terrain type categories.The proposed framework was validated on a quadruped robot.Overall,our investigations achieved a classification time-resolution of 1 s when the robot trotted over three kinds of terrains,thus recording a comprehensive success rate of 92.7%.

Novel Fast Operating Moving Coil Actuator with Compensation Coil for HVDC Circuit Breakers

DC circuit breakers are major enabling components for multi-terminal HVDC systems.Their key design targets are operating speed and efficiency.This paper proposes a novel moving coil actuator using a compensation coil topology to operate mechanical circuit breakers.This topology aims to significantly improve the magnetic field saturation and reduce the system inductance,so that the operating speed is increased.Four possible connection methods for the compensation coils are proposed and analyzed using finite element modeling,ensuing simulation results are compared and discussed.The operating speed of the moving coil actuator with compensation coils is significantly improved compared with the original moving coil actuator.The moving coil actuator with compensation coils can open a distance of 5 mm within 2.8 ms and the peak efficiency is 47%.