Short-circuit Protection Control Strategy for the 400Hz Ground Power Unit

A novel control method is suggested for the Ground Power Unit (GPU) in this research. In which, a short-circuit fault diagnosis and rapid-response overcurrent protection control strategy to regulate the current during load-side short circuit situations is utilized. The first strategy focuses on diagnosing short-circuit faults, while the second strategy involves a quick current limiting control method that utilizes adaptive reference feedforward and third harmonic elimination. The classical Proportional Resonant (PR) Control Algorithm is employed for both voltage control loop during normal operation mode, and overcurrent limiting control loop because of its benefits, particularly in eliminating tracking errors and compensating for the third-order current harmonic component that could potentially disrupt the protection circuit. A control mode switching circuit is carefully analyzed and designed to ensure a very quick switch to current mode control when the short circuit occurs, and a fast recovery to the normal voltage loop control once the overcurrent has been managed. An energy dissipation circuit is designed to provide the path for inductor to release stored energy through, thereby preventing overvoltage conditions at the output voltage across the load caused by the discharge current from the inductor. Both simulation results on Matlab and experimental results have been verified the effectiveness of the proposed control method in a variety of condition.