Discharge-Based DC-Bus Voltage Link Capacitor Monitoring with Repetitive Recursive Least Squares Method for Hybrid-Electric Aircraft

Hybrid-electric aircraft require a reliable power distribution architecture. The electrical drive system is connected to the power source via a DC-link composed mostly of capacitors—one of the faultiest power electronic components. In order to ensure the safe operation of the aircraft, DC-link capacitor condition monitoring is needed. The main requirements for such an algorithm are low data consumption and the possibility to use it in generator- or battery-powered systems. The proposed discharge-based repetitive recursive least squares (RRLS) method provides satisfactory estimates utilizing small data packages. Its execution during capacitor discharge makes it independent from the power source type. Based on the capacitor’s physical parameters, the computational complexity of the estimation process is reduced. Simulation validation and experimental tests were conducted. An analysis was carried out in a capacitance range between 705 μF and 1175 μF. The effective range of the algorithm is 881 μF–1044 μF, with an estimation error of less than 5%. Additionally, a range of changes in the time constant of the multiplier of 0.1–10 was tested in the simulation study.