Capacitor Energy-Based Current Sharing Control for More-Electric-Aircraft Onboard Microgrids With Parallel Sources

A current-sharing (CS) strategy based on capacitor energy control (CEC) is proposed for more-electric-aircraft (MEA) onboard microgrids with parallel sources. In conventional sources, the reference value is the dc-link voltage, which can be corrected based on the error between the output and the average current to realize CS. However, since the source characteristics are different, each source needs a proportion-integration-differentiation (PID) controller for CS control. In the CEC-based source, the reference value is the energy stored in the dc-link capacitor. The CEC calculates the reference output current, which is the input value of the field current controller. In the proposed CS control, the reference output current is corrected by the error between the output current and the average current. Since the current values are directly added up, differences between sources are eliminated. Fewer controllers are needed and the scheme is simplified. The dynamic performance and adaptability to operating condition variations are optimized. The CS error is low and dynamic responses are accelerated. A 270-
$\text{V}_{\mathrm {dc}}$
microgrid with parallel-connected doubly salient electromagnetic generators (DSEGs) is investigated and implemented. The CEC CS control and the conventional method are compared. The CS error, dynamic responses during connection, disconnection, speed variation, and load variation are investigated. The optimized performances of the CEC CS method are verified by experimental results.