Supercharger Control Apparatus for Boost Pressure Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional control apparatuses for internal combustion engines with response lag characteristics, such as variable nozzle type turbochargers, face challenges in maintaining accurate control due to overshooting and variations in characteristics over time, especially during transient operating conditions and sudden changes in engine demand.
Innovation Solution
A control apparatus that uses a feedback control algorithm with an integral term, including controlled variable detection, reference target value calculation reflecting response lag, allowable upper limit value calculation, and feedback target value calculation to ensure the detected controlled variable follows the calculated feedback target value, thereby improving control accuracy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the update inhibition period of the integral term is extended to avoid overshoot, then overshoot is suppressed, but the controlled variable may not reach the target value in time
Solution Approach 1:
The patent applies dynamics by making the update inhibition period variable rather than fixed. The control device dynamically adjusts the update inhibition period based on the absolute value of the controlled variable change amount: when the change amount is large, a longer inhibition period is applied to prevent overshoot; when the change amount is small, a shorter inhibition period allows faster convergence to the target value. This dynamic adjustment resolves the contradiction between stability and response speed.
2Speed
If the update inhibition period is shortened to improve response speed, then the controlled variable reaches the target faster, but overshoot occurs more frequently
Solution Approach 1:
The patent makes the update inhibition period dynamic by linking it to the absolute value of the controlled variable change amount. When the change amount is large (indicating high risk of overshoot), the inhibition period is extended to maintain stability. When the change amount is small (indicating low risk of overshoot), the inhibition period is shortened to improve response speed. This dynamic adaptation resolves the contradiction between response speed and control stability.
3Measurement precision
If conventional feedback control with integral term is used, then control accuracy is improved, but overshoot occurs due to response lag in transient conditions
Solution Approach 1:
The patent applies preliminary anti-action by inhibiting the update of the integral term during transient operating conditions when overshoot is likely to occur. By preventing the integral term from increasing during these critical periods, the system counteracts the tendency toward overshoot before it happens. This is done by comparing the absolute value of the controlled variable change amount against a threshold and conditionally updating the integral term accordingly.
4Measurement precision
If the integral term is updated continuously without inhibition, then control accuracy is maintained, but overshoot occurs during transient operating conditions
Solution Approach 1:
The patent applies preliminary anti-action by proactively inhibiting the integral term update when transient operating conditions are detected (when the absolute change amount exceeds the threshold). This prevents the harmful overshoot effect before it occurs by stopping the integral accumulation that would cause it, while still maintaining control accuracy through selective updating when conditions are stable.
Data Source
AI summary
A control apparatus using a feedback control algorithm including an integral term, which is capable of controlling a controlled object having a response lag characteristic while suppressing influences of aging and sudden changes in an operating state, and thereby improving control accuracy. The control apparatus that controls a supercharger includes an ECU. The ECU calculates a reference FB target pressure using a first-order lag equation, an allowable upper limit value based on a value obtained by adding a predetermined allowable range value to the reference FB target pressure, an FB target pressure such that an actual boost pressure does not exceed the allowable upper limit value, and a feedback correction term using a PI control algorithm such that the actual boost pressure becomes equal to the FB target pressure, and controls the actual boost pressure using a driver demand boost pressure and the feedback correction term.