Estimation of spring torque in an electronic throttle valve

This paper discusses the torque estimation of the spring which is internally connected between the motor shaft and the plate in an electronic throttle valve. In advanced engine control (such as EGR rate control), the throttle valve may need to be controlled in both opening and closing directions using a bidirectional driver in order to achieve more accurate and faster transient performance. The spring inside poses an additional force against the motor torque in opening direction, and an extra force that helps the valve to response faster in closing direction. Therefore the total torque acting on the valve plate is the sum of the motor torque, regulated by the motor drive controller, and the spring torque. Hence, it is important to estimate the spring torque and the information could then be used to improve the motor torque control. In this paper three different filters design are developed to estimate the spring torque while taking into account the model parameters uncertainty and/or the existence of white noise.