DC-DC Battery Pack Balancing Before Parallel Connection

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Solution Overview

Problem

Battery systems face issues with voltage imbalance between battery packs during charging, leading to high current flows when connected in parallel, which can damage the packs and other circuits, and existing solutions like limiting resistors waste energy by converting current to heat.

Innovation Solution

Implementing a processing circuit that monitors and controls DC-DC converters to balance voltages across battery packs during charging, ensuring they are equal before connecting them in parallel, thereby reducing the need for a limiting resistor or allowing its removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If battery packs are connected in parallel after charging, then energy can be distributed to electrical devices, but high current flows between battery packs with voltage differences can damage the packs and other circuits

Engineering Contradiction:

Improveenergy distribution capabilityVSAvoidhigh current damage risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary voltage balancing during the charging process by monitoring individual battery pack voltages and adjusting charging current distribution. This preliminary action ensures voltage equality is established before parallel connection, preventing harmful high current flows when packs are connected together.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors voltage levels of individual battery packs during charging and uses this feedback information to dynamically adjust charging current allocation. This feedback mechanism ensures voltage balance is maintained throughout the charging process, eliminating the need for high-power limiting resistors.

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If a limiting resistor is used to limit current between battery packs, then damage risk is reduced, but energy is wasted as heat in the resistor

Engineering Contradiction:

Improvecurrent damage protectionVSAvoidenergy conversion to heat

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

Instead of using a limiting resistor that dissipates energy as heat, the system performs preliminary voltage balancing during charging. This proactive approach eliminates voltage differences before parallel connection occurs, removing the need for energy-wasting limiting resistors while still providing current protection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system converts the potential harmful effect of voltage imbalances into a beneficial control opportunity by monitoring and adjusting charging currents. This transforms what would be a destructive situation (voltage difference causing high current) into a controlled process that actually improves overall system efficiency.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If battery packs charge at different rates or to different voltages, then charging flexibility is improved, but voltage imbalance causes high current flows when connected in parallel

Engineering Contradiction:

Improvecharging rate flexibilityVSAvoidvoltage difference current flow

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system applies different charging currents to individual battery packs based on their specific voltage levels and states. This localized control approach allows each pack to charge at its optimal rate while the controller continuously monitors and adjusts to maintain overall voltage balance, preventing harmful current flows.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The charging system dynamically adjusts current allocation to each battery pack based on real-time voltage measurements. This dynamic control enables flexible charging rates for different packs while continuously adapting to maintain voltage equality, eliminating the trade-off between flexibility and safety.

Inventive Principle:

Principle #15Dynamics

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 approach prevents high current flows between battery packs, reduces energy wastage, and maintains balanced voltages, ensuring safe and efficient energy distribution when packs are connected in parallel.

Implementation Method 1

the processing circuit 190 balances the voltage between the battery packs 110 and 120

Methodology Applied

Scientific EffectVoltage balancing:

Implementation Method 2

some of the current that flows through the limiting resistor is converted to heat which represents wasted energy

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS20240039305A1Systems and Methods for Balancing Battery Packs

Publication Date: 2024.02.01 ATLIS MOTOR VEHICLES INC

AI summary

A system and method for balancing the voltages between a plurality of battery packs while charging the battery packs. A processing circuit detects the respective voltages across the battery packs and the amount of energy used by a DC load. The processing circuit configures DC-DC converters to draw energy from the battery packs to provide energy to a DC load. The processing circuit configures DC-DC converters to draw more energy from the battery pack having the higher voltage than from the other battery packs to provide the energy to the DC load. Drawing a higher amount of energy from the battery pack having the higher voltage causes the voltage difference between the battery packs to decrease until the voltages across the battery packs are about equal.