Hybrid Vehicle Power Limit Control via Adaptive Switch Thresholds
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Solution Overview
Problem
Erroneous operation of switches in hybrid vehicles can lead to unintended variations in the upper limit value of discharge power, causing unexpected changes in driving force, which may not align with the occupant's intended driving experience.
Innovation Solution
A vehicle control system that includes a rotating electric machine, a power storage device, and an operation device, with a controller that differentiates between first and second operations based on operation duration or number to limit and cancel the upper limit value of discharge power, ensuring accurate determination of the occupant's intent and minimizing driving force variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the upper limit value of discharge power is varied by a simple switch operation, then the ease of operation is improved, but the reliability deteriorates due to erroneous operations
Solution Approach 1:
The patent applies dynamics by making the operation requirement adaptive based on the current power limit state. When the power limit is active, a longer operation duration (first threshold) is required to prevent accidental deactivation. When inactive, a shorter duration (second threshold) suffices for quick activation. This dynamic adjustment of operation thresholds resolves the contradiction by making the system both easy to operate legitimately and reliable against errors.
Solution Approach 2:
The patent changes the parameter of operation threshold duration based on the state of the power limit. By setting different time thresholds (first threshold > second threshold) depending on whether the power limit is currently active, the system adapts its operation requirements. This parameter change allows simple switch operation while preventing erroneous operations that could cause unintended power variations.
2Reliability
If the operation threshold is set high to prevent erroneous operations, then the reliability is improved, but the ease of operation deteriorates
Solution Approach 1:
The system dynamically adjusts the operation threshold based on the current state. When the power limit is inactive, a low threshold (second threshold) enables easy activation. When active, a high threshold (first threshold) prevents accidental deactivation. This state-dependent dynamic threshold resolves the contradiction by providing high reliability when needed while maintaining ease of operation when appropriate.
Solution Approach 2:
The system performs preliminary assessment by detecting the current power limit state before determining the appropriate operation threshold. This preliminary action allows the system to pre-set the correct threshold level, ensuring that operation is both easy and reliable based on the contextual state, rather than using a fixed high threshold that would always impede ease of operation.
3Productivity
If the upper limit value of discharge power is varied rapidly, then the productivity is improved, but the object-affected harmful factors increase due to abrupt driving force changes
Solution Approach 1:
The patent applies beforehand cushioning by implementing a gradual transition mechanism when varying the upper limit value of discharge power. Instead of abrupt changes, the power limit is adjusted incrementally over time, cushioning the impact on driving force. This prevents harmful abrupt variations while still achieving the productivity benefit of power limit adjustment, as the gradual change is imperceptible to occupants but effective for power management.
Data Source
AI summary
An ECU determines whether or not first operation for limiting an upper limit value of discharge power of a power storage device for supplying electric power to a rotating electric machine for generating a driving force of a vehicle has been received, by setting a first threshold value Tsw(1) of an operation duration Tsw of an operation device required to determine the reception of the first operation to be greater than a second threshold value Tsw(2) of operation duration Tsw of the operation device required to determine the reception of second operation for canceling the limitation of the upper limit value.