Abstract: A system (100) for connecting a fuel cell stack to an A.C. grid to provide power thereto is disclosed in which a voltage regulated D.C. bus (110) is provided to be coupled to the fuel cell stack, a bidirectional inverter (120) is coupled to the D.C. bus (110), and is to be coupled between the D.C. bus (110) and the A.C. grid. At least one D.C. auxiliary load (130) of the fuel cell stack is provided coupled to the D.C. bus (110). A D.C. to D.C. converter (140) is provided between the fuel cell stack and the D.C. bus (110).

Abstract: A method of and apparatus for monitoring rotor position in a reluctance machine includes determining the rate of change of current at a particular point at which current in the winding is arranged to freewheel. Preferably the point coincides with alignment of a rotor and a stator pole such that the rate of change of current is predicted to be zero. The magnitude and polarity of any variation from the predicted rate of change indicates a rotor position removed from the actual rotor position and whether it is in advance of, or retreated from, the predicted position.