Diesel Engine Feedforward Torque Control with Signal Decay
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Solution Overview
Problem
Diesel engines experience significant speed drops due to sudden load changes, leading to performance issues and operational instability, as existing control systems rely solely on feedback mechanisms that react after load changes occur, rather than anticipating and mitigating these changes.
Innovation Solution
Implementing a feedforward load anticipation mechanism with a signal decay function, where an electronic controller applies a feedforward offset to the feedback control command based on anticipated mechanical load events, ensuring seamless transition back to feedback control once the event has passed, thereby maintaining engine speed stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is used to adjust engine torque based on speed error, then engine speed can be maintained at target value, but large sudden load changes cause large speed drops before feedback can respond
Solution Approach 1:
The system performs preliminary action by detecting conditions indicative of an anticipated mechanical load event and applying a feedforward offset to the torque command before the load change actually occurs. This proactive adjustment prepares the engine to handle the upcoming load change, preventing large speed drops rather than reacting to them after they occur.
Solution Approach 2:
The system combines feedforward load anticipation with feedback control mechanisms. The electronic controller continuously monitors engine speed and compares it to the target speed, using this feedback to adjust the torque command. This closed-loop feedback ensures that any residual speed deviations are corrected, maintaining reliable engine speed stability.
2Reliability
If feedforward load anticipation is applied to address sudden load changes, then engine speed stability improves, but the control system complexity increases
Solution Approach 1:
The electronic controller serves as an intermediary that integrates both feedback control and feedforward load anticipation functions. It receives inputs from multiple sources (speed sensor, load event detection), processes them through coordinated control algorithms, and outputs a unified torque command. This intermediary approach allows the system to benefit from both control strategies without requiring separate complex control systems.
3Speed
If feedforward offset is applied continuously to anticipate load changes, then engine responds quickly to load events, but feedback control cannot resume full control after load event
Solution Approach 1:
The feedforward offset is implemented dynamically with a signal decay function that automatically reduces the offset magnitude over time after the load event occurs. This dynamic behavior allows the system to apply aggressive feedforward control when needed, then seamlessly transition back to feedback-dominated control as the offset decays, providing both rapid response and continuous adaptability.
Data Source
AI summary
Systems and methods of controlling operation of a diesel engine using feedforward load anticipation. An electronic controller determines a difference between an actual engine speed value of the diesel engine and a desired engine speed value, and generates a feedback control command based on the determined difference. In response to detecting one or more conditions indicative of an anticipated mechanical load event that will alter a total mechanical load of the diesel engine, the electronic controller applies a feedforward offset to the feedback control command in accordance with a feedback offset function. The feedback offset function causes the magnitude of the feedback offset to decrease over a period of time until the offset returns to zero (i.e., a signal decay function). The diesel engine is then operated based on the feedback control command and the feedforward offset.