Providing digital current ripple signal from analog armature current signal of DC motor, involves including current ripple detected from oversampling in further evaluation when non-conformance is detected

摘要

An analog armature current signal is subjected to a threshold-based A/D conversion after filtration process. The analog armature current signal is then oversampled when switching the DC motor ON during start-up phase, and when disconnecting the DC motor during the drifting phase limited in predetermined clock rate. The method involves comparing the current ripple detected from the threshold-based A/D conversion and the current ripple detected from the oversampling. The current ripple detected from the oversampling is included in further evaluation when non-sufficient conformance of current ripple is detected.