Patent ID: 7548036
Filing Date: 2009-06-16
Classification: H02H,H02P

Abstract:
1. A method of controlling the torque produced by a DC motor having a rotor to protect a mechanical system driven by said motor, said mechanical system comprising a combination of gears, levers, cams and/or sliding components arranged for interactive movement and having a particular elasticity in that movement and a limit at which compression of said particular elasticity by said motor torque can damage said mechanical system, said method comprising: monitoring that portion of the motor torque produced by rotor inertia by sampling an electrical current supplied to said motor, filtering said sampled current to substantially remove commutation ripples, and establishing a first derivative of said filtered sample of said electrical current, said first derivative current representing an inertial torque applied to said system by said rotor; and adjusting said electrical current supplied to said motor to stop or reverse said motor in response to an increase in said rotor inertia torque that exceeds a preselected threshold value selected to protect said mechanical system from damage caused by compression of said mechanical system that exceeds said particular elasticity.