Rate-Limited Feedforward Fueling for Drivetrain Stability
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Solution Overview
Problem
Existing drivetrain systems with electric drive machines face performance fluctuations due to unpredictable load changes, leading to engine lugging or overspeeding, as the engine responds slowly to changes in torque loading, and previous feedforward control methods are inadequate in managing these fluctuations effectively.
Innovation Solution
A drivetrain system with a controller that determines impending changes in loading on the traction motor and selectively rate-limits the fueling changes before they are transmitted to the engine, anticipating and mitigating performance deviations by implementing a rate-limited feedforward fueling strategy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If feedforward fueling is applied to anticipate load changes, then engine performance stability is improved, but engine responsiveness to sudden load changes deteriorates due to rate-limiting delays
Solution Approach 1:
The system dynamically adjusts the rate-limiting parameter based on operating conditions. When sudden load changes are detected, the controller temporarily increases the rate at which fueling commands are applied, allowing the engine to respond more quickly while still preventing excessive fluctuations. This dynamic adjustment resolves the contradiction by making the rate-limiting behavior adaptive rather than fixed.
Solution Approach 2:
The controller changes the fueling rate parameter based on the magnitude and rate of load change. By monitoring the derivative of the load signal and adjusting the fueling rate accordingly, the system can allow faster fueling responses during critical transient periods while maintaining rate-limiting during steady-state operation. This parameter change strategy balances stability and responsiveness.
2Speed
If the engine responds quickly to load changes by increasing fueling rate, then engine responsiveness is improved, but engine lugging and overspeeding worsen due to excessive fueling adjustments
Solution Approach 1:
The system applies preliminary anti-action by anticipating load changes before they fully manifest and applying counteracting fueling adjustments in advance. The feedforward component detects upcoming load increases and pre-applies fueling commands, preventing engine lugging before it occurs. Similarly, anticipated load reductions trigger pre-reduction of fueling to prevent overspeeding. This preliminary action resolves the contradiction by addressing load changes proactively rather than reactively.
Solution Approach 2:
The system combines feedforward anticipation with feedback correction. The feedback component continuously monitors actual engine performance and adjusts the fueling rate to correct any deviations caused by imperfect feedforward predictions. This closed-loop approach ensures that while the system responds quickly to load changes, it also maintains stability by correcting excessive or insufficient fueling adjustments in real-time.
3Stability of the object's composition
If rate-limiting is applied to prevent engine fluctuations, then engine stability is improved, but machine performance responsiveness deteriorates
Solution Approach 1:
The control system segments the fueling adjustment into multiple stages: an initial rapid adjustment phase that provides immediate response to load changes, followed by a rate-limited phase that prevents excessive fluctuations. This segmentation allows the system to achieve both quick responsiveness and subsequent stability, resolving the contradiction between responsiveness and stability.
Solution Approach 2:
The controller applies periodic monitoring and adjustment of the fueling rate, with different rate-limiting thresholds applied at different time intervals after a load change event. Immediately after a load change, the system allows faster fueling rates, then progressively applies stricter rate-limiting as the engine approaches steady-state. This time-varying periodic control resolves the contradiction by being responsive initially and stabilizing subsequently.
Data Source
AI summary
A drivetrain system for a mobile machine is disclosed. The drivetrain system may have an engine, a generator driven by the engine to generate electric power, and a traction motor driven by the electric power from the generator. The drivetrain system may also have a controller in communication with the engine, the generator, and the traction motor. The controller may be configured to determine a change in loading on the traction motor, and determine a change in fueling of the engine that will be required to accommodate the change in loading on the traction motor. The controller may also be configured to selectively rate-limit the change in fueling, and implement the rate-limited change in fueling prior to transmission of the change in loading on the traction motor to the engine.