Vehicle Battery Charge Control Using IBS Current Fallback
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Solution Overview
Problem
Conventional overcharge protection techniques for vehicle batteries rely solely on battery temperature, which varies with charging current and ambient temperature, leading to inefficiencies and potential battery swelling, and disconnecting the power source causes system failures.
Innovation Solution
An intelligent battery sensor generates a current signal monitored by a controller that adjusts the charging voltage set point based on battery current, temperature, or a constant value, using a gain adjustable integrator with integral anti-windup to prevent overcharging and noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage-based overcharge protection is used, then battery overcharge is prevented, but battery swelling still occurs and system reliability deteriorates
Solution Approach 1:
The system performs preliminary action by proactively monitoring battery current and adjusting the charging voltage setpoint before overcharge conditions develop. The controller continuously receives current signals from the intelligent battery sensor and adjusts the voltage setpoint for the auxiliary power module in advance, preventing battery swelling before it occurs rather than reacting after damage has happened.
Solution Approach 2:
The system implements feedback by continuously monitoring the actual battery current through the intelligent battery sensor and using this information to dynamically adjust the charging voltage setpoint. The controller compares the measured current against the maximum threshold and modifies the voltage setpoint accordingly, creating a closed-loop control system that adapts to real-time battery conditions.
2Measurement precision
If CAN-C bus is kept awake to ensure continuous current signal availability, then measurement precision is improved, but energy consumption increases
Solution Approach 1:
The system applies dynamics by making the CAN-C bus operational state adaptive rather than static. The bus transitions between awake and asleep states based on whether current monitoring is actually required. When the auxiliary power module is inactive or current is within normal ranges, the bus sleeps to conserve energy. When overcharge risk is detected or the APM is active, the bus wakes up to ensure continuous monitoring, optimizing the trade-off between measurement availability and energy consumption.
3Reliability
If battery current-based voltage adjustment is implemented, then overcharge protection is improved, but system complexity increases
Solution Approach 1:
The system implements parameter changes by dynamically modifying the voltage setpoint parameter based on battery current conditions. Rather than changing the fundamental control architecture or adding complex control algorithms, the system adjusts a single key parameter (voltage setpoint) based on current measurements. This simple parameter adjustment approach provides effective overcharge protection while minimizing increases in system complexity.
Data Source
AI summary
Electrified vehicle battery overcharge protection techniques monitor an intelligent battery sensor (IBS) current signal via a controller area network communication (CAN-C) bus and an output current of an auxiliary power module (APM) when the IBS current signal is unavailable. A controller then intelligently adjusts charging of the battery system to be battery current-based, battery temperature-based, or at predetermined constant value, based on a determined validity of the IBS current signal, the measured battery system current, and an awake/asleep status and responsiveness of the CAN-C bus.