Electronic Throttle Structure Accelerator Pedal Accelerator pedal is a device that reflects the mind of the driver. Its core is a potentiometer type position sensor, which converts the pedal displacement into electrical signal. Improvement of the throttle of the DA462 engine is transmitted to the electronic unit (ECU). Unlike the mechanical throttle, the driver cannot directly control it. Throttle Body The throttle body is mainly composed of a drive motor, a throttle body, a throttle position sensor, an idle switch position sensor, and a return spring.
Electronic throttle structure as shown in 2. Electronic Throttle Nonlinearity In the electronic throttle control system, the main problem in the mechanical structure is the nonlinear problem that affects the control of the electronic throttle system. There are three kinds of non-linear factors: viscous friction and sliding friction Electronic throttle valves are subjected to both viscous friction and sliding friction during the course of motion, causing instability in the dynamic process. It is generally reduced to Coulomb friction and expressed by the formula: Tf is the Coulomb friction; ω is the motor speed; Fs>0.
The spring nonlinearity has a return spring on the left side of the throttle valve plate. When the drive signal is cut off, the throttle valve returns to the minimum opening position under the action of the return spring to ensure the safety of the system. Because it is a torsion spring, it has nonlinearity. The characteristics of the nonlinear equation: Tsp is the return spring force; θ is the throttle angle; θ0 is the spring gain; D is the spring offset.
The backlash non-linear gear reduction mechanism transmits the motor drive torque to the throttle valve plate. Inevitably, there is an intermeshing gap between the gears. Generally, the backlash nonlinearity is regarded as a function of the input torque and expressed as: y=f(x, δ) Where: x is the input torque; y is the output torque; δ is the width of the dead zone. Among the three nonlinear factors, the most significant one is the spring nonlinearity, followed by stick-slip friction and backlash nonlinearity.
Throttle nonlinear control Electronic throttle valve system model According to the dynamics, the dynamic equation of the system is: ω is the motor speed, J is the moment of inertia, Z is the motor current, B is the viscous damping coefficient, and Kt is the motor torque constant. Throttle valve rotation angle and motor speed change relationship: θ = kω type: k is the gear ratio. In the system circuit equation: Kv is the motor back-EMF constant; L is the motor inductive reactance; R is the motor resistance; U is the input voltage.
In the nonlinear characteristics of backlash, the nonlinearity is a function of the output current z of the motor. Taking into account the influence of the dead zone, the use of the controller in the project to use the PID control does not require the precise model of the control object, and it is easy to Implementation, and there are a large number of precedents for reference, is the preferred control strategy for electronic throttle systems. In view of the nonlinear and time-varying characteristics of the electronic throttle valve system, it is necessary to improve the basic algorithm.
Self-tuning fuzzy PID control can be used. The structure and working principle are shown in 3.
Conclusion According to the requirements of the electronic throttle, Bosch's electronic throttle control unit was selected to match the selected electronic throttle control system with the original engine management system. The main content of the match is that the electronic control system should eliminate the influence of the non-linear factors of the above parts, so that the opening of the throttle valve meets the requirements of the engine operating conditions. The simulation results show that using self-tuning fuzzy PID control, the target signal can be well tracked, and no overshoot phenomenon will occur.
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