Mixed-Chemistry Battery Charging with DC-DC Converter Bypass
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Solution Overview
Problem
Existing energy storage systems in vehicles, particularly those using multiple battery chemistries, face challenges in efficiently managing power transfer and charging performance, especially when trying to achieve fast charging without being limited by the power rating of the DC-DC converter.
Innovation Solution
A system comprising a bi-directional DC-DC converter connected to a charging bus, selectively connected to both a propulsion battery assembly and a supplemental battery assembly of different chemistries. The system includes a controller that manages switching to put the system into various charging modes, allowing for simultaneous charging of both battery assemblies or bypassing the supplemental battery for direct charging of the propulsion battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single battery assembly is used in the vehicle, then the system complexity is low, but the charging rate and energy density are limited by the DC-DC converter power rating
Solution Approach 1:
The battery system is segmented into two separate battery assemblies: a first battery assembly connected to the DC-DC converter for standard charging, and a second battery assembly with higher energy density for fast charging. This segmentation allows each battery to be optimized for its specific charging mode, enabling the second battery to be charged faster without being limited by the DC-DC converter power rating.
Solution Approach 2:
A controller is introduced as an intermediary component to manage power distribution between the two battery assemblies. The controller receives power from the charging system and intelligently directs it to either the first or second battery assembly based on charging requirements, enabling fast charging capability while maintaining system coordination and managing the increased complexity.
2Productivity
If the DC-DC converter power rating is increased to enable faster charging, then the charging rate improves, but the cost and size of the converter increase
Solution Approach 1:
The charging system is segmented into two paths: a standard charging path through the existing DC-DC converter to the first battery, and a fast charging path directly to the second battery. This allows the DC-DC converter to maintain its original, smaller size while the system as a whole achieves faster charging capability through the second battery's direct charging capability.
3Productivity
If a mixed chemistry battery system is implemented, then the energy density and charging performance improve, but the control and management complexity increases
Solution Approach 1:
The controller serves as an intermediary that manages the complexity of coordinating two different battery chemistries. It monitors the state of charge, temperature, and charging status of both batteries, and intelligently switches between charging modes (charging first battery only, charging second battery only, or charging both simultaneously) to optimize charging efficiency while handling the control complexity.
4Loss of time
If the supplemental battery assembly is charged simultaneously with the propulsion battery, then the overall charging time is reduced, but the power distribution control becomes more complex
Solution Approach 1:
The system implements dynamic switching between different charging modes through the controller. The controller can transition between charging only the first battery, charging only the second battery, or charging both batteries simultaneously based on real-time conditions such as state of charge, temperature, and power availability. This dynamic control reduces charging time while managing the complexity through adaptive decision-making.
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 enhances charging efficiency and rate by allowing the supplemental battery system to be charged more quickly than in existing systems, without being limited by the DC-DC converter's power rating, thereby improving overall vehicle performance and range.
Implementation Method 1
a direct current (DC)-DC converter connected to a charging bus and selectively connected to a propulsion battery assembly and a supplemental battery assembly
Implementation Method 2
the DC-DC converter is a bi-directional buck-boost converter
Data Source
AI summary
A system for controlling power transfer includes a direct current (DC)-DC converter connected to a charging bus and selectively connected to a propulsion battery assembly and a supplemental battery assembly, the propulsion battery assembly having a first chemistry and configured to supply power to an electric motor of a vehicle, the supplemental battery assembly having a second chemistry that is different than the first chemistry. The system also includes a charger connected to the charging bus at a first side of the DC-DC converter, the charging bus connected to a load at a second side of the DC-DC converter, and a controller configured to control the DC-DC converter to perform a charging operation.