Dynamometer Control Using Pre-acquired Speed-Torque Data
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Solution Overview
Problem
Conventional engine testing apparatuses face delays in reproducing the rapid engine rotation speed changes at startup due to mechanical, dynamometer, and control system response delays, which inaccurately simulate real vehicle conditions, and existing feedforward control methods may misalign with actual engine behavior.
Innovation Solution
An engine testing apparatus and method that involves storing control command values from real vehicle rotation speed changes and using these values to control the dynamometer, synchronizing with an engine output signal to reproduce engine behavior accurately, including inertia compensation and friction simulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is used to make the dynamometer torque coincide with the target torque, then the torque measurement accuracy is improved, but the response delay increases due to mechanical and control system delays
Solution Approach 1:
The patent applies preliminary action by pre-acquiring the relationship between engine rotation speed and torque, and pre-calculating the feedforward torque values based on this relationship. This allows the dynamometer to anticipate the required torque changes before they occur, compensating for the inherent delays in feedback control systems and mechanical response.
2Loss of time
If feedforward control is used to control the dynamometer torque, then the response delay is reduced, but the engine behavior cannot be accurately reproduced due to misalignment with actual engine behavior
Solution Approach 1:
The patent combines feedforward control with feedback control in a hybrid approach. The feedforward component provides timely response by pre-calculating torque based on the stored speed-torque relationship, while the feedback component continuously monitors the actual torque and makes corrections. This dual approach maintains both rapid response and accurate reproduction of engine behavior.
3Measurement precision
If the dynamometer is connected to the engine under test for torque measurement, then the torque can be measured, but the response delay prevents accurate reproduction of rapid engine speed changes
Solution Approach 1:
The system performs preliminary acquisition of the engine speed-torque relationship during a calibration phase before actual testing. This pre-acquired data is stored and used to generate feedforward torque commands during dynamic testing, allowing the system to respond to rapid speed changes without the delays inherent in real-time measurement and feedback control.
Data Source
AI summary
An engine testing apparatus is provided with a memory portion for storing a control command value obtained when the rotation speed of a dynamometer is changed by the control command value in accordance with the change of the engine rotation speed in a real vehicle in a period in which the engine behavior in a real vehicle is reproduced without connecting the dynamometer to an engine under test. The engine testing apparatus is provided with an output portion that supplies the control command value stored in the memory portion to the dynamometer with reference to an engine output signal showing the start of the reproducing period.