EV Battery Output Control for High-Speed Overheating
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Solution Overview
Problem
Electrified vehicles face battery overheating issues during high-speed traveling, which can lead to unintended power-offs, despite the presence of battery cooling systems. Limiting battery output power to prevent overheating degrades high-speed traveling performance.
Innovation Solution
The vehicle determines whether to limit battery output power based on the ratio of regenerative braking, which varies with charging and discharging cycles. This decision is made considering the ratio of charging to discharging, average battery output power, and battery temperature to adjust the derate ratio for the battery output limit value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If battery output power is limited to prevent overheating, then battery temperature is reduced, but high-speed traveling performance deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of battery output limits based on real-time monitoring of battery temperature, state of charge, and driving conditions. The control system continuously adapts the output limitation strategy, transitioning between different control modes (output limitation, output increase, output maintenance) based on current thermal and operational states, thereby optimizing both thermal management and performance throughout the driving cycle
Solution Approach 2:
The system changes key operational parameters including battery output limit values, cooling system activation thresholds, and regenerative braking ratios based on real-time battery temperature and state of charge measurements. By dynamically adjusting these parameters rather than applying fixed limitations, the system prevents overheating while minimizing performance degradation during high-speed traveling
2Temperature
If battery cooling systems are used to alleviate overheating, then battery temperature is controlled, but the system becomes insufficient for extended high-speed traveling
Solution Approach 1:
The patent combines multiple control strategies into an integrated thermal management system that merges output limitation control, active cooling control, and regenerative braking management. This hybrid approach integrates the advantages of different control methods, allowing the system to maintain effective temperature control during extended high-speed traveling by switching between and combining these control modes as needed
Solution Approach 2:
The control system performs multiple functions simultaneously: it monitors battery temperature, manages output limitations, controls cooling system activation, and optimizes regenerative braking. This multi-functional approach allows a single control system to address both short-term temperature control and long-term thermal management needs during extended high-speed operation
3Temperature
If regenerative braking ratio is increased to reduce battery output, then battery overheating is alleviated, but charging efficiency may be affected
Solution Approach 1:
The system continuously monitors battery temperature, state of charge, and regenerative braking ratios, using this feedback to dynamically adjust the regenerative braking strategy. When battery temperature rises during high-speed traveling, the system increases regenerative braking ratio to reduce net charging demand and allow heat dissipation, while maintaining overall charging efficiency by optimizing the timing and magnitude of regenerative events based on real-time feedback
Data Source
AI summary
An electrified vehicle includes: a battery; a motor drive device configured to drive a motor through an inverter, based on a voltage of the battery; and a battery controller configured to determine whether to perform output limiting on the battery, based on whether a ratio of regenerative braking is less than or equal to a preset ratio, wherein the ratio of regenerative braking is varied according to an amount of charging of the battery and an amount of discharging of the battery within a preset time interval, and adjust, based on the output limiting being performed on the battery, a derate ratio associated with a battery output limit value.