Sensing mechanical transitions from current of motor driving hydraulic pump or other mechanism

Abstract

A circuit and method for detecting an operating transition of a mechanical apparatus driven by a hydraulic prime mover comprising a hydraulic pump driven by an electric motor, the operating transition causing a change in the force applied by the mechanical apparatus on the prime mover. A motor current sensing circuit is connected in a motor power supply circuit to provide a motor current signal representing motor current. A bandpass filter receives the motor current signal and provides a filtered motor current signal consisting essentially of motor current signal components in the frequency range from a lower frequency boundary greater than zero Hz to an upper frequency boundary below substantially all the motor noise frequencies. A comparison circuit compares the filtered motor current signal to a first selected threshold level and outputs a signal representing the occurrence of the operating transition when the filtered motor current signal exceeds the selected threshold level. The circuit is preferably implemented with a digital controller programmed to perform these operations.

Dependencies are inferred from the claim text.