Patent ID: 9742329
Date: 2017-08-22
CPC Classifications: H02P

Claim:
1. A motor controller, comprising: a drive circuit including a plurality of switches, a motor winding, and a current sensor in an H-bridge configuration; and a processing device coupled to the drive circuit and causing cycles of a drive current through the drive circuit; in each cycle the processing device causing a drive current through the drive circuit for a minimum amount of time and causing no current during an off period of time, during the off period of time the processing device causing a fast decay for a first duration followed by a slow decay for a second duration of a back current in the drive circuit; the processing device causing a comparison of the drive current through the current sensor to a threshold current at the end of each minimum amount of time; and the processing device varying the first duration and the second duration in each cycle based on the comparison of the drive current to the threshold level for a current cycle and an immediate previous cycle.