Turbine Inlet Temperature Control via Dynamic Setpoint Ramping
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Solution Overview
Problem
Existing methods for controlling turbine inlet temperature in exhaust turbines are either too abrupt, leading to noticeable torque reduction and potential overcompensation, or they result in undercompensation and risk of turbine damage due to thermal inertia and inadequate control strategies.
Innovation Solution
A method that involves determining the turbine inlet temperature and entering a torque reduction mode when it exceeds a setpoint temperature, gradually increasing the setpoint temperature to the maximum hardware temperature, and adjusting engine parameters like torque, EGR rate, and injection timing to smoothly control the turbine inlet temperature, preventing overshoot and ensuring minimal torque reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque is reduced in a stepwise manner to protect the turbine, then turbine inlet temperature is controlled below hardware limit, but torque reduction is noticeable and disconcerting to the vehicle operator
Solution Approach 1:
The patent applies dynamics by continuously adjusting the torque reduction amount in real-time based on the difference between actual and target turbine inlet temperatures. Instead of fixed stepwise reduction, the system dynamically modifies torque reduction magnitude according to temperature feedback, making the protection response adaptive and smooth rather than abrupt and noticeable.
Solution Approach 2:
The patent implements feedback control by continuously monitoring turbine inlet temperature and using this information to adjust torque reduction commands. The control system calculates temperature deviation from the target and uses this error signal to modulate the torque reduction amount, creating a closed-loop control that prevents both overheating and excessive torque loss.
2Device complexity
If torque is reduced in an open-loop manner, then implementation is simple, but overcompensation occurs at some operating conditions and undercompensation at others risking turbine damage
Solution Approach 1:
The patent transforms the open-loop control into a closed-loop system by continuously measuring turbine inlet temperature and using this feedback to adjust torque reduction commands. The control amount is dynamically determined by the temperature difference between actual and target values, ensuring accurate protection across all operating conditions without over or under-compensation.
Solution Approach 2:
The patent changes the control parameter from fixed torque reduction to variable torque reduction based on temperature deviation. By making the torque reduction amount a function of real-time temperature measurements rather than a predetermined fixed value, the system adapts to different operating conditions and achieves reliable turbine protection without excessive complexity.
3Reliability
If control temperature is set equal to maximum hardware temperature, then turbine protection margin is maximized, but significant temperature overshoot occurs during transient periods causing damage risk
Solution Approach 1:
The patent applies preliminary action by setting the target temperature below the maximum hardware temperature to anticipate thermal inertia effects. This proactive approach prevents temperature overshoot by aiming for a conservative target that accounts for the system's thermal response delay, eliminating the need for reactive damage mitigation after overshoot occurs.
Solution Approach 2:
The patent implements beforehand cushioning by establishing a safety buffer in the temperature control target. By setting the target temperature lower than the maximum hardware limit, the system creates a protective margin that absorbs thermal inertia effects, cushioning against potential overshoot and preventing turbine damage before it can occur.
4Object-affected harmful factors
If control temperature is set below maximum hardware temperature to provide safety margin, then temperature overshoot is reduced, but steady state temperature is lower than necessary requiring greater torque reduction
Solution Approach 1:
The patent applies dynamics by making the target temperature a dynamic parameter rather than a fixed value. The target temperature adjusts based on operating conditions and thermal state, allowing the system to achieve smooth transient response without excessive torque reduction. This dynamic adjustment optimizes the balance between preventing overshoot and maintaining engine performance.
Solution Approach 2:
The patent changes the control parameter from a fixed conservative temperature setpoint to a variable target that adapts to system state. By modifying the target temperature based on real-time conditions and thermal inertia considerations, the system achieves both smooth transients and optimal steady-state performance without unnecessary torque loss.
Data Source
AI summary
A method and system to control an engine to maintain turbine inlet temperature utilizes two temperature thresholds: a control initiation temperature and a maximum hardware temperature. An engine parameter is adjusted in a closed-loop manner based on an error, which is a difference between a setpoint temperature and the turbine inlet temperature. The setpoint temperature is initially the control initiation temperature. However, after control over turbine inlet temperature is established, the setpoint temperature ramps gradually to maximum hardware temperature. In one embodiment, the engine parameter is engine torque. Other engine parameters affecting turbine inlet temperature include timing and duration of fuel injection pulses, EGR rate, gear selection, and intake throttle position, any of which can be used in place of, or in combination with, torque for controlling turbine inlet temperature.