HEV Engine Misoperation Control via Operating Point Deviation
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Solution Overview
Problem
In power split type hybrid electric vehicle systems, sudden unintended acceleration can occur due to engine misoperation, which poses a risk to safety and can lead to battery overdischarge.
Innovation Solution
A method is implemented to detect and prevent sudden unintended acceleration by determining if the engine's operating point deviates from a target profile, where a control torque of 0 Nm is output by the generator, fuel supply to the engine is stopped, and the driving torque of the driving motor is limited to prevent excessive acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine operates without strict control to maintain power output, then the vehicle can respond quickly to power demands, but sudden unintended acceleration may occur due to misoperation
Solution Approach 1:
The control device predicts the engine operating point in advance by using a pre-stored map that correlates accelerator pedal opening with target operating points. This prediction allows the system to prepare appropriate control torques before misoperation occurs, enabling quick response while maintaining safety through pre-planned control strategies.
Solution Approach 2:
The control device continuously monitors the actual engine operating point and compares it with the predicted operating point. When a deviation exceeding a predetermined threshold is detected, the system immediately adjusts the generator control torque to counteract the misoperation. This closed-loop feedback mechanism ensures rapid correction of unintended acceleration while maintaining normal operation during legitimate power demands.
2Reliability
If the generator applies strong reaction force control to prevent unintended acceleration, then safety is improved, but the engine cannot efficiently transmit torque to the drive shaft
Solution Approach 1:
The control device applies generator control torque only when necessary - specifically when the actual engine operating point deviates from the predicted operating point by more than a predetermined threshold. During normal operation, the generator applies minimal or no counter-torque, allowing efficient torque transmission. When misoperation is detected, the system applies excessive counter-torque (enough to stop the unintended acceleration) only for the duration needed to correct the deviation.
Data Source
AI summary
A method for controlling a sudden unintended acceleration due to misoperation of an engine in a power split type hybrid electric vehicle (HEV) system, the method including when a determination is made that a delta revolution per minute (RPM) of an engine is out of a predetermined criterion, determining that an operating point of the engine does not move along a profile defined according to a target operating point of the engine and the sudden unintended acceleration is possible. The delta RPM is a difference of value between a current RPM of the engine and a profile RPM of the engine required to move to the target operating point of the engine from a current operating point of the engine.