Transformer-Based Battery Cell Balancing Circuit
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Solution Overview
Problem
Existing battery systems face challenges in balancing battery cells connected in series, as they often convert energy into heat during balancing, and transistors in integrated circuits are complicated to drive due to floating source potentials.
Innovation Solution
A battery system with at least three cells connected in series, using a transformer with a secondary winding for energy storage, rectifying diodes, and a switching transistor that maintains a constant potential, allowing energy transfer between cells without heat conversion and simplifying transistor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistance balancing is used to balance battery cells, then cell voltage equality is achieved, but energy is converted into heat causing energy loss
Solution Approach 1:
The patent introduces a transformer as an intermediary device between battery cells to enable energy transfer. The transformer couples cells through electromagnetic induction, allowing energy to be transferred from higher-voltage cells to lower-voltage cells without direct resistive connection, thus avoiding heat loss while achieving voltage equalization.
Solution Approach 2:
The patent replaces the mechanical/resistive balancing system with an electromagnetic field-based system. Instead of using resistors to dissipate energy as heat, the system uses transformer electromagnetic coupling to transfer energy between cells, substituting a more efficient physical mechanism for the traditional approach.
2Extent of automation
If transistors are used in integrated circuits for balancing, then cell balancing control is achieved, but transistor control becomes complicated due to floating source potentials
Solution Approach 1:
The patent connects the source terminal of each transistor to a common reference potential through the transformer structure. This equipotential connection eliminates the floating source potential problem, providing a stable reference for transistor control and simplifying the driving circuitry while maintaining automated balancing control.
3Power
If multiple battery cells are connected in series to meet performance requirements, then system performance is improved, but cell voltage inequality increases over time
Solution Approach 1:
The transformer acts as an intermediary that enables energy redistribution among series-connected cells. By coupling cells through the transformer, the system can transfer energy from cells with higher voltage to those with lower voltage, maintaining voltage equality across the series string and preserving both performance and 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
Balances battery cells efficiently without converting energy into heat and simplifies transistor control, enabling effective balancing within integrated circuits.
Implementation Method 1
at least one energy storage means (44; 44') which is formed by the secondary winding (42; 42') of at least one transformer (40; 40') and is designed to temporarily store energy stored in the second battery cell (Z2)
Implementation Method 2
at least two rectifying means (46, 46'; 48, 48') which are designed to allow current to flow in one direction only
Data Source
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AI summary
The battery system according to the invention comprises at least three battery cells connected in series, wherein a first battery cell is connected to a second battery cell and the second battery cell is connected to a third battery cell, at least one switching means, at least two rectifying means, which are designed to allow current flow in one direction only, and at least one energy storage means for temporarily storing stored energy in the battery system. The at least one energy storage means is designed to temporarily store energy stored in the second battery cell after the at least one switching means has been switched on. The at least two rectifying means are designed, after the at least one switching means has been switched off, to supply energy stored in the at least one energy storage means to the first battery cell when the ratio of the voltage of the first battery cell to the voltage of the third battery is lower than the ratio of the target voltage of the first battery cell to the target voltage of the third battery cell, and to supply energy stored in the at least one energy storage means to the third battery cell when the ratio of the voltage of the first battery cell to the voltage of the third battery cell is higher than the ratio of the target voltage of the first battery cell to the target voltage of the third battery cell.