A Coreless Axial-Flux Permanent-Magnet Generator for Automotive Applications

We present a modified structure of an axial flux permanent magnet generator for an automotive application. The generator has a coreless double-stator structure; one is stationary, and the other can be moved to achieve the desired performance. This provides a simple mechanical way to weaken flux in order to extend the speed range of the generator for a constant output power. The excitation is from permanent magnets mounted on the rotors, and the windings are concentrated with simple circular form to achieve a sinusoidal waveform with very low harmonic contents. We have designed and analyzed the generator by both the three-dimensional finite-element method and the analytic approach. The calculated values coincide very well with the experimental results.