Patent ID: 6051942
Filing Date: 2000-04-18
Classification: H02P

Abstract:
A method for controlling the rate of current change in a phase winding of a reluctance machine from a level of approximately zero current towards a predetermined peak current value, the phase winding being coupled by a power switching device to a source of available DC voltage, the method comprising the steps of:establishing a fixed chopping frequency for applying voltage pulses to the phase winding where the interval between the initiation of adjacent voltage pulses defines a first time interval;selecting a maximum active interval for applying the DC voltage to the phase winding, the maximum active interval corresponding to a percentage of the first time interval that is less than 100%, the maximum active interval defining a maximum net average voltage for application to the phase winding,applying the available DC voltage to the phase winding to initiate a voltage pulse when the rotor reaches a predetermined angular position with respect to the stator such that the current begins to increase from a level of approximately zero towards the predetermined peak current value;monitoring the current in the phase winding and comparing a representation of the current in the phase winding with a representation of the predetermined peak current value; andremoving the application of the available DC voltage from the phase winding at a time corresponding to the earlier of:(i) a time when the phase current reaches the predetermined peak current value; or(ii) the time when the percentage of the first time interval defined by the maximum active interval has passed since the initiation of the voltage pulse.