Battery Power Limit Control via Predictive Saturation Ratio
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Solution Overview
Problem
Current systems lack an effective method to determine the discharge and charge power limit values of battery cells, which are crucial for ensuring continuous power delivery without exceeding maximum allowed currents, leading to potential voltage drops or overcharging.
Innovation Solution
A system utilizing a current sensor and microprocessor to calculate discharge and charge power limit values based on battery cell equivalent circuit models, including ohmic resistance, time-varying resistance, and predictive saturation ratios, to determine the amount of power that can be safely delivered or received by the battery cell over a predetermined time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If power delivery to battery cell is increased to improve charging speed, then charging efficiency is improved, but risk of exceeding maximum allowed charge current and causing overcharging increases
Solution Approach 1:
The system performs preliminary calculations of the charge power limit value before charging begins. The microprocessor calculates the maximum allowed voltage gain, determines the current level required to reach it within a predetermined time, and establishes the charge power limit based on these preliminary assessments, preventing overcharging before it can occur
Solution Approach 2:
The system continuously monitors the actual voltage across the battery cell during charging and compares it to the maximum allowed voltage. The charge power limit is dynamically adjusted based on feedback from voltage measurements and the calculated predictive saturation ratio, ensuring the charge current remains within safe limits while maximizing charging speed
2Power
If discharge current is increased to improve power delivery, then power output is improved, but voltage drop below minimum allowed voltage occurs
Solution Approach 1:
The system calculates the discharge power limit value in advance by determining the maximum allowed voltage drop from the current voltage to the minimum allowed voltage. The microprocessor computes the current level that would cause this voltage drop within a predetermined time and uses this information to establish the discharge power limit before discharge begins
Solution Approach 2:
The system continuously monitors the actual voltage across the battery cell during discharge and compares it to the minimum allowed voltage. The discharge power limit is dynamically adjusted based on feedback from voltage measurements and the calculated predictive saturation ratio, ensuring the discharge current maintains voltage within acceptable ranges while maximizing power output
3Measurement precision
If complex battery models are used to improve calculation accuracy, then power limit determination precision is improved, but computational complexity increases
Solution Approach 1:
The system transforms the complex battery cell equivalent circuit model parameters (multiple resistors and capacitors) into a simplified predictive saturation ratio value through mathematical transformations. This allows the microprocessor to accurately predict future voltage levels using a single calculated parameter rather than tracking multiple circuit parameters, maintaining precision while reducing computational burden
Solution Approach 2:
The system extracts the essential predictive information from the complex battery model by calculating a single predictive saturation ratio value that captures the future voltage behavior. This extracted parameter condenses the information from multiple resistors and capacitors into one usable value, simplifying the power limit calculation while preserving accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately determines the power limits for battery cells, preventing voltage drops during discharge and overcharging, thereby ensuring reliable and efficient power management.
Implementation Method 1
a current sensor adapted to generate a first signal having a current value therein, the current value indicating a current level flowing through the battery cell
Implementation Method 2
calculate a maximum allowed voltage drop value corresponding to a difference between a voltage measured across the battery cell at the first time and a minimum allowed voltage of the battery cell... based on a first ohmic resistance value of a battery cell equivalent circuit model
Data Source
AI summary
A system for determining a discharge power limit value and a charge power limit of the battery cell is provided. The system has a microprocessor that calculates a maximum allowed voltage drop value of the battery cell. The microprocessor calculates a first current level through the battery cell for a predetermined amount of time to obtain the maximum allowed voltage drop value. The microprocessor calculates a first discharge power limit value, if the first current level is less than or equal to a maximum allowed discharge current. The microprocessor calculates a second discharge power limit value, if the first current level is greater than the maximum allowed discharge current.