Battery Control Unit Derating Current to Maintain Voltage Stability
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Solution Overview
Problem
Secondary batteries face challenges in maintaining stable output parameters as their voltage rapidly changes near limit values, leading to potential deviations from the operating voltage range during charging and discharging.
Innovation Solution
A system and method that include voltage, current, and temperature measurement units, along with a control unit to determine a deration target current value and output value based on predefined resistance change rates, state of charge, and temperature, adjusting the output parameter when the battery voltage approaches a threshold, thereby preventing voltage deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the output parameter is updated according to state of charge and temperature, then the discharging capability and charging capability are optimized, but the voltage stability deteriorates when voltage approaches limit values
Solution Approach 1:
The control unit determines voltage change rate in advance before the voltage reaches limit values. When the voltage change rate exceeds a threshold, the system proactively adjusts the output parameter (reduces maximum current or available power) to prevent voltage from deviating outside the operating range, rather than waiting for voltage to actually reach the limits.
Solution Approach 2:
The system continuously monitors the voltage change rate of the secondary battery and uses this feedback to dynamically adjust the output parameter. The control unit compares the measured voltage change rate against a threshold and modifies the maximum current or available power accordingly, creating a closed-loop control system that maintains voltage stability while preserving discharging capability.
2Speed
If the voltage change rate increases near limit voltages, then the battery reaches charge/discharge limits faster, but the control response time becomes insufficient to prevent voltage deviation
Solution Approach 1:
The system detects voltage change rate in advance and triggers output parameter adjustment before the voltage actually reaches the limit values. This preliminary action compensates for the fast voltage change rate by initiating control measures early, ensuring sufficient time for the control system to respond and prevent voltage deviation even when voltage changes rapidly.
3Power
If the maximum current is maintained at high levels, then the power output is maximized, but the voltage may deviate outside the operating range when approaching limit voltages
Solution Approach 1:
The system dynamically adjusts the maximum current based on real-time voltage change rate monitoring. When the voltage change rate is within acceptable thresholds, the maximum current is maintained at high levels to maximize power output. When the voltage change rate exceeds the threshold near limit voltages, the maximum current is reduced to prevent voltage deviation, creating a dynamic balance between power output and voltage range compliance.
Solution Approach 2:
The control unit changes the output parameter (maximum current or available power) based on the voltage change rate condition. By adjusting this key parameter in response to voltage dynamics, the system maintains high power output during normal operation while ensuring voltage stays within the operating range when approaching charge or discharge limits.
Data Source
AI summary
The present disclosure discloses a system and method of adjusting an output parameter of a secondary battery. The system according to the present disclosure determines a voltage, a current, and a temperature of the secondary battery, determines a state of charge of the secondary battery using the current, determines a deration target current value calculated from a maximum value of a predefined resistance change rate, which corresponds to the state of charge and the temperature, and an output maintaining time, when the voltage of the secondary battery decreases to a preset threshold voltage or lower, and provides an output parameter including at least one of the deration target current value and a deration target output value determined therefrom to a control system of a load device supplied with power from the secondary battery.