Magnetic Field Enhancement Characteristic of an Axially Parallel Hybrid Excitation DC Generator

The magnetic field enhancement characteristic of an axially parallel hybrid excitation generator (APHEG) is revealed and analyzed in this article. The APHEG consists of a permanent magnet machine part (PMMP), a flux modulation machine part (FMMP), and a diode rectifier. The magnetic fields of the two parts are interactional despite the independent flux paths, which provides the possibility to enhance the FMMP field at the expense of weakening the PMMP field. By taking advantage of that, the combination of the PMMP and FMMP can effectively boost the output power in the defined voltage-boost region as the weakening of the PMMP field is negligible. In addition, the magnetic field of the FMMP can be further enhanced by regulating the rotor shift angle. Based on the analysis of the phasor diagrams, it is found that the flux amplitudes and phase displacement angles of the two parts are mutually restrictive and decide the optimized rotor shift angle range of the APHEG. Finally, a prototype APHEG has been developed, and the experiments verify the phasor diagrams and simulation analysis.