Parallel Dual Battery Pack System Eliminating Switching Losses
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Solution Overview
Problem
Dual battery packs with a power conversion device and switch experience switching losses, limited operation voltage range, and inefficiencies in regenerative charging, leading to potential damage and power loss, especially when the lithium-ion battery pack's state of charge is high, preventing efficient energy utilization.
Innovation Solution
A vehicle battery system comprising two battery packs connected in parallel without a power conversion device, featuring a lithium-ion battery pack with carbon-based negative electrodes and nickel-based or lithium-iron-phosphate positive electrodes, and a lead-acid battery pack, allowing for efficient power distribution and charging without additional power conversion members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a power conversion device including a switch is used to supply power between battery packs, then power supply control is enabled, but switching loss occurs and fuel efficiency deteriorates
Solution Approach 1:
The patent removes the power conversion device and switch from the system, extracting the source of switching losses. The battery packs are connected directly through parallel connection, eliminating the need for active power conversion while maintaining power supply capability between the lithium-ion battery pack and lead-acid battery pack.
2Ease of operation
If a switch is used for power supply, then power distribution is controlled, but the switch may be forcibly turned off causing damage and power loss
Solution Approach 1:
The switch component is completely removed from the system. Instead of controlling power distribution through a switch that may be forcibly turned off, the patent uses direct parallel connection between battery packs, allowing automatic power flow based on voltage differences without mechanical or electronic switching components that can fail.
3Reliability
If the lithium-ion battery pack has a limited operation voltage range, then battery safety is maintained, but regenerative charging is blocked
Solution Approach 1:
The patent introduces a second voltage dimension by adding a lead-acid battery pack with a different voltage range (10V-15V) to complement the lithium-ion battery pack's voltage range (15V-18V). This multi-dimensional voltage architecture allows the system to accept regenerative braking energy across a broader voltage spectrum, with the lead-acid battery accepting charges when lithium-ion voltage is too high, thereby resolving the conflict between safety limits and charging capability.
4Device complexity
If the lithium-ion battery pack is connected in parallel with the alternator and lead-acid battery pack, then the system complexity is reduced, but the lithium-ion battery pack requires specific voltage range matching
Solution Approach 1:
The patent creates a composite battery system combining two different battery technologies (lithium-ion and lead-acid) with complementary characteristics. This composite architecture allows the system to operate across a broader voltage range (10V-18V) by leveraging the strengths of each battery type, with the lead-acid battery handling lower voltage operations and the lithium-ion battery handling higher voltage operations, thereby maintaining voltage range compatibility without increasing system complexity.
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 configuration reduces internal resistance, enhances charging and discharging speeds, and covers the entire voltage range required by vehicles, improving fuel efficiency and preventing switch damage by eliminating the need for a power conversion device.
Implementation Method 1
The negative electrode active material includes a carbon-based material having an interlayer spacing of a (002) plane of 0.34 nm to 0.50 nm in X-ray diffraction measurement using copper (Cu) Kα lines
Implementation Method 2
Each of the first battery cells may include a positive electrode. The positive electrode may include a positive electrode active material
Implementation Method 3
a first battery pack connected in parallel with an alternator and including a plurality of first battery cells connected in series
Data Source
AI summary
A lithium battery system includes a first battery pack including a plurality of first battery cells connected in series. The first battery pack is configured to be connected in parallel to an alternator and a second battery pack, and has a lower capacity than the second battery pack. A negative electrode of each of the first battery cells includes a negative electrode active material. The negative electrode active material includes a carbon-based material having an interlayer spacing of a (002) plane of 0.34 nm to 0.50 nm in X-ray diffraction measurement using copper (Cu) Kα lines.