Electronic throttle systems are becoming more and more important in today's motor vehicles. These systems consist of:
a throttle valve with an electrical actuator and a transmission
a position feedback
an electronic acceleration pedal
an electronic control unit (ECU)
a semiconductor h-bridge for driving the motor.
The electronic acceleration pedal gives a set point to the ECU. A control signal is generated and moves the motor of the throttle valve with a semiconductor h-bridge to the requested position. The voltage drop of a potentiometer is used here as control feedback signal.
The potentiometer in the throttle valve is moved very often and has a rough environment like high temperature and vibrations. Therefore this system has a lot of problems with mechanical attrition and reliability during the whole system lifetime. The accuracy of the position control decreases over time.
To avoid mechanical wear and tear, Infineon Technologies has developed a new concept for measuring the throttle position, based on a contactless sensor. The GMR-C6 is a giant magneto-resistive sensor which detects changes in the direction of a magnetic field. The present SAE paper will describe the construction of the sensor, the signal conditioning and the software algorithms.
Moreover, a semiconductor h-bridge which has been specially developed for electronic throttle control will also be introduced.
A complex logic circuit in the smart power device allows a very extensive diagnosis which is necessary to fulfill OBDII.
Our vision for the future is a mechatronic solution for the throttle. That means all components are integrated into the throttle package. The control of the position is done internally. Only 4 wires are left: 2 for supply and 2 for communication.