This paper presents a direct power control strategy for a variable speed axial flux permanent magnet synchronous generator. The method consists on calculating the instantaneous power by measuring the machine currents and estimating the back electromotive force (back-emf). The real-time back-emf estimation is based on tracking the no-load voltage through off-line harmonic analysis, and the mechanical position and speed, obtained with an incremental encoder. A 3 kW laboratory prototype has been built to verify the performance of the proposed strategy. Experimental results are shown and discussed.