Battery Equalization Circuit Using Triac Transformer Topology

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Solution Overview

Problem

In multiple-cell batteries, voltage imbalances due to production tolerances and operational differences lead to premature failure, as weaker cells are overstressed, and existing passive equalization methods waste excess charge as heat rather than redistributing it to undercharged cells.

Innovation Solution

A battery equalization circuit that monitors and actively adjusts the voltage of each cell using a bi-directional AC signal, with triacs and transformers to charge or discharge cells based on their voltage relative to the total battery voltage, ensuring all cells remain balanced and extending battery life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If passive equalization is used to equalize battery cells, then cell voltage balance is improved, but energy is wasted as heat and device complexity increases

Engineering Contradiction:
Improvecell voltage balanceVSAvoidenergy waste
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent recovers excess energy from overcharged cells by converting it to usable electrical power through AC/DC conversion, rather than dissipating it as heat. The energy management circuit captures this recovered energy and redistributes it to undercharged cells, thereby eliminating energy waste while maintaining cell voltage balance.

Inventive Principle:
Principle #34Discarding and recovering

Solution Approach 2:

The patent introduces an intermediary AC/DC conversion circuit between the battery cells and the energy management system. This intermediary converts the AC signal generated from voltage differences back into DC voltage, enabling efficient energy redistribution without direct cell-to-cell energy transfer, thus reducing energy losses.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If passive equalization is used to equalize battery cells, then cell voltage balance is improved, but device complexity and cost increase

Engineering Contradiction:
Improvecell voltage balanceVSAvoidcircuit complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent implements a multi-functional energy management circuit that simultaneously performs cell voltage monitoring, AC/DC conversion, energy storage, and energy redistribution. This universal circuit replaces multiple separate equalization circuits, reducing overall device complexity and cost while maintaining effective cell voltage balance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the equalization function with the energy management function into a single integrated system. The same circuit that manages overall battery energy also handles cell-level equalization through AC/DC conversion, eliminating the need for separate equalization circuits and reducing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Duration of action of stationary object

If active equalization is used to redistribute charge among cells, then battery life is extended, but device complexity increases

Engineering Contradiction:
Improvebattery lifeVSAvoidequalization circuit complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent enables the battery system to self-equalize by automatically detecting voltage imbalances and activating the AC/DC conversion circuit when needed. The system monitors cell voltages and autonomously redistributes energy without external control, extending battery life while minimizing the complexity of control circuitry.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent implements periodic monitoring of cell voltages and activates equalization only when imbalances are detected. This periodic action rather than continuous operation reduces the complexity of the equalization circuit while still effectively extending battery life through timely intervention.

Inventive Principle:
Principle #19Periodic action

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 solution effectively extends battery life by maintaining balanced cell voltages, preventing overcharging, and redistributing charge efficiently, thus avoiding waste and reducing stress on individual cells.

Implementation Method 1

a first transformer winding (135, 435) configured to receive an output voltage of an AC generator

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a first upper triac (171, 471) connected between the first positive battery node (101, 401) and the first upper transformer node (201, 421); a first lower triac (172, 472) connected between the first negative battery node (102, 402) and the first lower transformer node (202, 422)

Methodology Applied
Scientific EffectTriode for alternating current switching:

Data Source

PatentUS9337670B2Circuit and method for battery equalization
Publication Date: 2016.05.10 NXP USA INC

AI summary

A battery equalization circuit is provided, including: a positive battery node connecting to a positive node of a battery cell in a battery circuit with a plurality of other battery cells; a negative battery node connected to a negative node of the battery cell; a transformer winding receiving an AC voltage, the transformer winding having an upper transformer node and a tower transformer node; an upper triac connected between the positive battery node and the upper transformer node; a lower triac connected between the negative battery node and the lower transformer node; a control circuit for controlling the upper triac and the lower triac based on a measured cell voltage between the positive battery node and the negative battery node, and a total battery voltage of the battery circuit; and an isolation element connected between the control circuit and a data bus.