Design, Analysis, and Comparison of Automatic Flux Regulator With Automatic Voltage Regulator-Based Generation System for DC Marine Vessels

The generation system in the dc marine vessel is expected to be comprised of wound rotor synchronous generator (WRSG) which is interfaced with an active front-end (AFE) rectifier. For such system, WRSG flux and dc voltage at the AFE rectifier output are controlled independently. WRSG flux is maintained by the field excitation circuit of WRSG for which automatic voltage regulator (AVR) has been traditionally employed. AVR operates by regulating the WRSG terminal voltage, thus demands additional tuned filter for the application in the dc marine vessel. This filter increases the size of the generation system along with additional cooling requirements at higher load. With this regard, this paper introduces an automatic flux regulator (AFR)-based field excitation system where the WRSG flux is maintained directly and is independent of the measurement of the terminal voltage. Small-signal analysis is done to design the control loop of the AFR-based field excitation circuit. To verify its efficacy, comparison with the AVR-based dc generation system is conducted. The comparison has been done on the basis of control response and marine operation.