Battery Pack Current Detection via PDM Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion battery packs in small mobile devices face challenges in detecting remaining battery charge due to the large size of analog-to-digital converters, making it difficult to integrate a detector in compact designs.
Innovation Solution
A battery pack with a current detecting unit, a modulating unit that converts analog signals to PDM signals, and a CPU that executes programs to convert PDM signals to PCM data, allowing for accurate remaining battery charge calculation, while integrating key components into a small semiconductor integrated circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an analog-to-digital converter is used to convert current values into PCM data for detecting remaining battery charge, then the remaining battery charge can be detected, but the circuit size becomes large making it difficult to install in a small sized battery pack
Solution Approach 1:
The patent changes the data format from multi-bit PCM to 1-bit PDM, fundamentally altering the parameter of digital representation. This parameter change enables the use of a sigma-delta modulator instead of a traditional analog-to-digital converter, significantly reducing circuit size while maintaining the ability to detect remaining battery charge through accumulation of PDM data
Solution Approach 2:
The patent replaces the mechanical/analog analog-to-digital converter with a digital sigma-delta modulator that generates PDM signals. This substitution uses digital signal processing techniques to achieve the same measurement function with much smaller circuitry, as the sigma-delta modulator can be implemented efficiently in digital logic
Data Source
AI summary
A battery pack is disclosed. The battery pack includes a battery; a current detecting unit which detects charging and discharging currents of the battery and outputs an analog signal corresponding to the charging and discharging currents; a modulating unit which modulates the analog signal to be a PDM (pulse density modulation) signal by applying a PDM modulation to the analog signal; a memory in which a conversion program for converting the PDM signal into PCM (pulse code modulation) data and a remaining battery charge calculating program for calculating a remaining battery charge by accumulating the PCM data are stored; and a CPU, which converts the PDM signal into the PCM data which are digital data by being supplied the PDM signal from the modulating unit while executing the conversion program stored in the memory, and calculates the remaining battery charge by accumulating the PCM data while executing the remaining battery charge calculating program stored in the memory.