Adaptive Clamp Circuit for Li-Ion Cell Voltage Balancing
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Solution Overview
Problem
Conventional cell balancing circuits for multi-cell Li-Ion battery packs face challenges in balancing adjacent cells simultaneously while maintaining low cost and avoiding unintended activation of switching circuits due to excessive current, which can lead to inefficiencies and increased circuit complexity.
Innovation Solution
A circuit with separate switching circuits and an adaptive clamp circuit that dynamically balances voltage across multiple cells by providing independent control signals and shunting excessive current to prevent unintended activation, using external power transistors and current sources to reduce the need for dedicated control pins and enhance balancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive balancing is used to balance cell voltages, then the circuit cost is reduced, but excessive energy is wasted as heat
Solution Approach 1:
The patent introduces an adaptive clamp circuit as an intermediary component that monitors and controls the voltage difference between adjacent cells. This clamp circuit acts as a mediator that prevents excessive current flow and unintended switching activation, enabling more efficient balancing while maintaining the simplicity and low cost of passive balancing architecture.
2Productivity
If external transistor networks are employed to balance voltages, then balancing efficiency is improved, but additional control pins are required increasing circuit cost
Solution Approach 1:
The patent merges the functions of voltage balancing and switching control into a unified passive balancing architecture. By combining the balancing resistors with adaptive clamp circuits that automatically prevent unintended activation, the system achieves efficient balancing without requiring separate external transistor networks and their associated control pins, thereby reducing circuit complexity and cost.
Solution Approach 2:
The adaptive clamp circuit provides self-service functionality by automatically monitoring voltage differences and preventing unintended switching activation without requiring external control signals. This self-regulating mechanism enables efficient balancing while eliminating the need for additional control pins that would increase circuit complexity.
3Speed
If simultaneous balancing of adjacent cells is implemented, then balancing speed is improved, but unintended activation of switching circuits occurs due to excessive current
Solution Approach 1:
The patent applies preliminary anti-action by implementing adaptive clamp circuits that proactively prevent unintended switching activation before it can occur. The clamp circuits are positioned to preemptively block excessive current flow between adjacent cells, thereby enabling simultaneous balancing operations without risking unintended switching circuit activation and maintaining system reliability.
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
Enables concurrent and efficient cell balancing with reduced circuit complexity and cost, preventing unintended activation of switching circuits and maintaining optimal gate drive voltage, thus improving battery pack performance and runtime.
Implementation Method 1
an adaptive clamp circuit connected between each pair of adjacent cell inputs, each adaptive clamp circuit being configured to shunt excessive current to inhibit unintended activation
Implementation Method 2
separate switching circuits, each being configured to balance a respective cell voltage for a respective cell based on a respective switching control signal
Data Source
AI summary
A circuit providing voltage cell balancing is provided. The circuit includes a cell balancing network comprising separate switching circuits, each being configured to balance a respective cell voltage for a respective cell of a plurality of voltage cells based on a respective switching control signal. A control circuit includes a plurality of current sources, each of the plurality of current sources selectively connected to a respective one of the separate switching circuits to independently control operation of each of the separate switching circuits of the cell balancing network to balance the voltage across the plurality of voltage cells.