Control Device for DPF Temperature Constraint Management
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Solution Overview
Problem
Existing control devices, such as reference governors, struggle to maintain DPF temperature within constraints when internal combustion engine operating conditions suddenly change, particularly during transitions to idle operation, as they rely on current operating conditions for future predictions, leading to potential DPF temperature exceedance.
Innovation Solution
A control device that uses a prediction model incorporating operating conditions and controlled variables to simulate future state quantities, allowing for the calculation of virtual current values of controlled variables to ensure constraints are met, even under sudden changes in operating conditions, by iteratively modifying target values based on virtual current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a reference governor uses current operating conditions for future prediction, then the control logic is simple and easy to implement, but the DPF temperature may exceed constraints when operating conditions suddenly change
Solution Approach 1:
The control device performs preliminary action by determining a preliminary target value of the controlled variable before the operating condition actually changes. This preliminary target value is calculated based on predicted future operating conditions, allowing the system to proactively adjust the controlled variable to prevent constraint violations when the operating condition transition occurs.
Solution Approach 2:
The control device dynamically switches between using current operating conditions and predicted future operating conditions based on the detected operating condition transition. When a sudden change is detected, the system transitions from static prediction (using current conditions) to dynamic prediction (using future conditions), making the control logic adaptive to changing circumstances.
2Reliability
If the target value is modified based on future prediction under current operating conditions, then the DPF temperature can be controlled within constraints during steady operation, but the control becomes inadequate when sudden transitions to idle operation occur
Solution Approach 1:
The control device makes the prediction basis dynamic by switching between current operating conditions and predicted future operating conditions. During steady operation, it uses current conditions for simple prediction. When a sudden transition is detected, it dynamically switches to using future predicted conditions, thereby adapting the control strategy to the changing operational context and maintaining effectiveness across different operating scenarios.
Solution Approach 2:
The control device changes the parameter used for prediction from current operating conditions to predicted future operating conditions when a sudden transition is detected. This parameter change allows the system to account for the upcoming idle operation state in advance, ensuring that the target value modification remains effective even during transient operating condition changes.
3Ease of operation
If no preliminary adjustment is made to the controlled variable, then the system responds naturally to operating condition changes, but the constraint may be violated during sudden transitions
Solution Approach 1:
The control device applies preliminary action by adjusting the controlled variable in advance based on predicted future operating conditions before the actual transition occurs. This preliminary adjustment prevents the constraint violation that would otherwise occur during sudden transitions to idle operation, while maintaining natural system response during steady operation.
Solution Approach 2:
The control device applies preliminary anti-action by counteracting the potential harmful effect (constraint violation) before it occurs. By detecting the upcoming operating condition change and adjusting the controlled variable in advance, the system prevents the temperature excursion that would violate the constraint, thereby eliminating the harmful effect before it can manifest.
Data Source
AI summary
This control device is configured to, based on a premise that an operating condition of a plant is a specific operating condition that is defined in advance, search for a virtual current value of a controlled variable for ensuring that a specific state quantity does not conflict with a constraint in the future using a prediction model, set the virtual current value which was found by the search to a target value of the controlled variable, and determine a manipulated variable of the plant so that an actual current value of the controlled variable approaches the target value. Due to this configuration, even if the operating condition of the plant suddenly changes to the specific operating condition, the controlled variable of the plant can be adjusted in advance so that the specific state quantity in the specific operating condition does not conflict with the constraint.