An improved method of commutating an electronically commutated DC motor shuts
off application of power between the end of one current pulse and the beginning
of the subsequent current pulse. Based upon the instantaneous rotation speed, one
calculates at what instant to shut off the power. During the power interruption,
the disconnected winding is operated in short-circuit mode using two MOSFET transistors,
and the decay of the current is monitored. When the current reaches a predetermined
reduced value, the terminals of the winding are switched to a high-resistance state,
until the subsequent current pulse is started. This has the advantage that less
reactive power occurs during operation, and one need not install as bulky a storage
capacitor as the capacitors used heretofore.