Regenerated Energy Absorption Methods for More Electric Aircraft Starter/Generator System

In more electric aircraft, more motor loads are applied onboard. When the motor is braking, the regenerated energy needs to be absorbed to avoid dc-link voltage variations. Two regenerated energy absorption methods are proposed for the generator based on diode rectifiers and the starter/generator (SG) based on active rectifiers, respectively. When the regenerated power is lower than other loaded power, both SG and generator systems can absorb it by reducing the output power. When the regenerated power is higher than other loaded power and the SG is directly connected to the engine shaft, the regenerated energy can be absorbed by changing the SG operation from generating to motoring. The regenerated energy can be returned directly to the dc link without extra devices, and the dc-link voltage is under control during the regenerated energy absorption. The efficiency is improved and the heat is reduced by the proposed regenerated energy absorption methods. The generator and SG systems are implemented, and the regenerated energy absorption methods are verified by experiments. The efficiency of the onboard electrical power system has improved.