Voltage Sampling Circuit Using Subtractor for Battery Pack
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Solution Overview
Problem
Conventional voltage sampling circuits for battery packs require expensive Analog Front-Ends (AFE) with Analog-to-Digital Converter (ADC) modules to manage high voltages, and AFEs without ADC modules cannot detect high voltages, leading to increased costs and limitations in versatility.
Innovation Solution
A voltage sampling circuit comprising a low-side AFE, a high-side AFE, a subtractor, and a switch control circuit that allows sampling of voltages from at least two sets of cells in series or parallel configurations without an ADC module, using a subtractor to adjust input terminals based on connection type to safely transmit analog voltages to a MicroController Unit (MCU).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an AFE with ADC module is used to detect high voltage, then the voltage detection capability is improved, but the circuit cost increases
Solution Approach 1:
The patent divides the voltage detection function into two parts: the AFE circuit performs analog voltage sampling without ADC, and a separate subtractor circuit performs the digital voltage calculation. This segmentation allows the AFE to be simpler and cheaper while still achieving high voltage detection capability through the combined system.
Solution Approach 2:
The patent introduces a subtractor circuit as an intermediary component between the AFE and the microcontroller. This subtractor processes the analog voltage signal from the AFE and enables the microcontroller to calculate the actual battery voltage without requiring an expensive ADC module in the AFE itself.
2Ease of manufacture
If an AFE without ADC module is used to reduce cost, then the circuit cost is reduced, but the high voltage detection capability is lost
Solution Approach 1:
The AFE circuit is designed to perform multiple functions: it can sample voltages from both single-voltage and dual-voltage battery configurations, and it works with or without ADC modules. This multi-functionality allows the same AFE design to be used across different product lines, reducing development costs while maintaining high voltage detection capability through the subtractor circuit.
Solution Approach 2:
The patent changes the operational parameters of the AFE circuit by adjusting the reference voltage input based on the battery configuration (single-voltage or dual-voltage). By dynamically changing the reference voltage parameter, the same AFE hardware can accurately measure different voltage ranges without requiring different hardware designs.
3Adaptability or versatility
If dual-voltage battery pack is used to expand versatility, then the adaptability is improved, but the voltage sampling complexity increases
Solution Approach 1:
The patent implements dynamic switching of the subtractor circuit's reference voltage input based on the battery configuration. When in dual-voltage mode, the subtractor uses one reference voltage; when in single-voltage mode, it uses another. This dynamic adaptation allows the circuit to handle different configurations without requiring separate dedicated circuits for each mode, thereby reducing overall complexity.
Solution Approach 2:
The voltage sampling circuit is designed with universal functionality to handle both single-voltage and dual-voltage battery packs using the same basic architecture. The AFE, subtractor, and associated components can operate in different modes depending on the battery configuration, eliminating the need for separate sampling circuits and reducing system complexity.
Data Source
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AI summary
A voltage sampling circuit is provided for sampling voltage of at least two sets of cells (1, 2) in a battery pack comprises at least two analog front ends comprising a low-side Analog Front End, AFE (11), connected to a first set of cells (1) and a high-side AFE (12) connected to a second set of cells (2), a subtractor (20) has a positive input terminal and a negative input terminal, the positive input terminal connecting to the output of the high-side AFE (12) for receiving the analog voltage output by the high-side AFE (12). When the first set of cells (1) is connected with the second set of cells (2) in series, the negative input terminal of the subtractor (20) connecting to the total positive of the first set of cells (1), when the first set of cells (1) is connected with the second set of cells (2) in parallel, the negative input terminal of the subtractor (20) is grounded.