Battery Pack Analog Switch for Temperature-Compensated Cell Sensing
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Solution Overview
Problem
Existing battery packs with limited input ports in voltage sensing and balancing circuits cannot accurately measure voltages from all battery cells due to temperature-dependent differences in diode characteristics, leading to incomplete voltage balancing and detection.
Innovation Solution
Incorporating a first diode in a backward direction from a flying capacitor coupled to an analog-to-digital (A/D) converter, paired with a second diode having the same temperature characteristics, to store battery cell voltage values and suppress temperature-dependent voltage differences, allowing for accurate voltage measurement and balancing across all cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If battery cells are directly coupled to the A/D converter, then voltage measurement is simplified, but temperature-dependent voltage differences cannot be suppressed
Solution Approach 1:
The patent introduces diodes as intermediary components between the battery cells and the A/D converter. These diodes act as mediators to compensate for temperature-dependent voltage differences. The first diode is coupled in a backward direction from a flying capacitor to correspond to a second diode packaged therewith as a single set, creating an intermediary path that suppresses temperature effects on voltage measurements.
Solution Approach 2:
The patent changes the electrical parameters of the measurement circuit by introducing diodes with specific temperature characteristics. The diodes' forward voltage characteristics are utilized to counteract temperature-dependent variations in battery cell voltages, effectively changing the measurement parameters to achieve temperature compensation.
2Reliability
If more battery cells are connected to the voltage sensing circuit, then complete voltage balancing is achieved, but the limited input ports cannot handle all cells
Solution Approach 1:
The patent makes the voltage sensing circuit multi-functional by enabling it to handle more battery cells than the number of physical input ports. The flying capacitor and diode configuration allows the circuit to sense voltages from multiple cells sequentially or in parallel, making the limited input ports serve multiple measurement functions.
Solution Approach 2:
The patent implements a nested measurement structure where the flying capacitor and diode configuration creates a nested path for voltage sensing. This allows the voltage sensing circuit to access multiple battery cell voltages through a limited number of input ports by creating nested measurement paths.
3Ease of manufacture
If diodes with different temperature characteristics are used, then circuit design is simplified, but voltage measurement differences occur due to temperature
Solution Approach 1:
The patent applies local quality by selecting diodes with specific temperature characteristics for particular positions in the circuit. The first diode coupled in backward direction and the second diode packaged as a single set are chosen with matched temperature characteristics to locally compensate for temperature effects in the voltage measurement path.
Solution Approach 2:
The patent ensures homogeneity by using diodes with matched temperature characteristics. The first and second diodes packaged as a single set have consistent temperature-dependent properties, creating homogeneous behavior in the voltage measurement circuit that eliminates differential temperature effects.
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
This configuration enables comprehensive voltage sensing and balancing across all battery cells, compensating for temperature effects and preventing surge currents, thereby ensuring stable and accurate voltage measurement and control.
Implementation Method 1
a first diode coupled in a backward direction from a flying capacitor, which is coupled to an analog-to-digital (A/D) converter
Implementation Method 2
the second diode thereby suppresses a difference between voltages measured from battery cells depending on temperature characteristics of the first and second diodes
Implementation Method 3
the first diode preventing surge current from a voltage supply in a voltage input path from a flying capacitor to an A/D converter
Data Source
AI summary
An analog switch and a battery pack using the same are provided. The analog switch can compensate for temperature dependence of voltages measured from a battery cell before applying the measured voltages to an analog-to-digital (A/D) converter. In an embodiment of the analog switch, a first diode is coupled in a backward direction from a flying capacitor, which is coupled to the A/D converter, to correspond to a second diode packaged therewith as a single set. The first diode is positioned in a battery cell voltage input path to store battery cell voltage values in the flying capacitor, while the second diode suppresses a temperature-related difference caused by the first diode to voltages measured from the battery cell.