Hybrid Vehicle Torque Control via Battery SOC
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Solution Overview
Problem
Hybrid electric vehicles face issues with torque reduction requests from traction control systems (TCS) leading to battery state of charge (SOC) depletion and compromised motor performance, as they rely solely on motor torque after engine torque is reduced, resulting in unsatisfied driver demands and poor fuel efficiency.
Innovation Solution
A method and apparatus for controlling torque reduction in hybrid electric vehicles that determine engine and motor torque commands based on TCS requests and battery SOC, calculating available charging amounts and adjusting factors using transcendental functions to optimize torque distribution and prevent SOC depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hybrid electric vehicle decreases engine torque first and then motor torque to satisfy TCS request, then the TCS request for driving torque limit is satisfied, but the battery SOC runs out and motor power performance deteriorates
Solution Approach 1:
The patent dynamically adjusts the torque reduction strategy based on real-time battery SOC levels. When SOC is high, the system prioritizes motor torque reduction; when SOC is low, it prioritizes engine torque reduction. This dynamic adaptation resolves the contradiction by making the torque distribution strategy flexible rather than fixed, ensuring TCS requirements are met while preserving battery charge when necessary.
Solution Approach 2:
The system changes the operational parameters of both the engine and motor based on battery SOC thresholds. Different torque command strategies are applied depending on the SOC level, transforming the control approach from a static sequence (engine first, then motor) to a parameter-dependent dynamic strategy that optimizes energy usage while satisfying TCS torque limits.
2Reliability
If the hybrid electric vehicle continuously uses motor torque after engine torque becomes 0, then the TCS request is satisfied, but the battery SOC depletes and the vehicle cannot start smoothly again
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors battery SOC levels during TCS operation. When SOC drops below a threshold, the system automatically adjusts the torque distribution strategy to reduce motor torque and increase engine torque contribution. This feedback loop prevents excessive motor operation and ensures the vehicle can restart smoothly, resolving the contradiction between continuous TCS operation and battery preservation.
Solution Approach 2:
The system employs periodic assessment of battery SOC during TCS activation, switching between different torque control modes based on energy availability. This periodic evaluation prevents continuous motor operation that would deplete the battery, instead creating a rhythm of torque adjustment that maintains both TCS functionality and adequate battery charge for future operations.
3Reliability
If the hybrid electric vehicle decreases engine torque to satisfy TCS request, then wheel spin is controlled, but driver demand torque cannot be satisfied and fuel efficiency deteriorates
Solution Approach 1:
The patent dynamically balances torque distribution between engine and motor based on real-time driving conditions and TCS requirements. Rather than simply reducing engine torque, the system dynamically adjusts both engine and motor torque commands to maintain total torque output that satisfies driver demand while controlling wheel spin, thus resolving the contradiction between wheel spin control and driver torque satisfaction.
Solution Approach 2:
The system performs preliminary calculation of optimal torque distribution before executing TCS torque reduction. By pre-determining the torque commands that will satisfy both TCS limits and driver demand, the system avoids excessive engine torque reduction that would compromise fuel efficiency and driver satisfaction, while still achieving effective wheel spin control.
Data Source
AI summary
A method for controlling torque reduction of a hybrid electric vehicle including a motor and an engine as a power source includes: determining whether a request for a driving torque limit by a traction control system (TCS) is generated; calculating a motor torque command when the request for the driving torque limit by the TCS is generated; calculating an engine torque command based on the calculated motor torque command; calculating an available amount of charging of the motor according to a state of charge (SOC) of a battery of the hybrid electric vehicle; and determining a final motor torque command and a final engine torque command based on the calculated available amount of charging of the motor.