Traction Battery Charging with Dynamic DC/DC Voltage Balancing
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Solution Overview
Problem
The charging efficiency of traction batteries is limited by energy storage unit capacity and energy mismatch during alternate charging and discharging processes.
Innovation Solution
A charging apparatus with multiple energy storage units connected in series, each equipped with a DC/DC converter, adjusts output voltages to match the energy storage units' current voltages, ensuring balanced energy transfer during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If alternate charging and discharging is used to implement fast charging, then charging speed is improved, but charging efficiency is limited by energy storage unit capacity and energy mismatch
Solution Approach 1:
The energy storage system is divided into N independent energy storage units, each with its own DC/DC converter. This segmentation allows independent control of each unit's voltage and energy transfer, enabling the system to overcome the capacity limitations of a single energy storage unit while maintaining fast charging capability.
Solution Approach 2:
The patent implements dynamic voltage adjustment for each energy storage unit based on real-time state of charge (SOC) monitoring. The DC/DC converters dynamically adjust output voltages to ensure balanced energy transfer during alternate charging and discharging, preventing energy mismatch and maximizing charging efficiency throughout the fast charging process.
2Quantity of substance
If multiple energy storage units are connected in series, then capacity is increased, but energy mismatch between units occurs during charging and discharging
Solution Approach 1:
Each energy storage unit is equipped with an independent DC/DC converter that provides localized voltage control. This allows each unit to operate with optimized voltage characteristics based on its individual state of charge, preventing energy mismatch while maintaining the increased capacity benefits of series connection.
Solution Approach 2:
The system continuously monitors and adjusts the voltage parameters of each energy storage unit based on real-time SOC measurements. By dynamically changing voltage parameters during charging and discharging cycles, the system maintains energy balance across all units while utilizing their combined increased capacity.
3Productivity
If DC/DC converters are used to control voltage output, then energy transfer is optimized, but device complexity increases
Solution Approach 1:
Each DC/DC converter is designed to perform multiple functions: voltage matching, energy transfer control, and SOC-based dynamic adjustment. This multi-functionality reduces the need for additional separate control systems, managing complexity while maintaining high energy transfer efficiency across all energy storage units.
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 optimizes energy utilization, avoiding energy mismatch and enhancing charging efficiency by fully utilizing the capacity of energy storage units.
Implementation Method 1
each energy storage unit includes an energy storage battery and a first DC/DC converter connected to the energy storage battery
Data Source
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AI summary
Embodiments of this application provide a charging method and charging apparatus for traction battery, which can improve performance of charging apparatuses. The charging method is applied to a charging apparatus. The charging apparatus includes N energy storage units connected in series, where each energy storage unit includes an energy storage battery and a first DC/DC converter connected to the energy storage battery, and each charging period of the charging apparatus includes a stage in which a traction battery is charged and a stage in which the traction battery discharges to the N energy storage units. The charging method includes: in the discharge stage, obtaining a current voltage of the energy storage battery in each energy storage unit; determining, based on the current voltage of the energy storage battery in each energy storage unit, a first voltage output by the first DC/DC converter in each energy storage unit, where the first voltage output is inversely proportional to the current voltage of the energy storage battery; and sending the first voltage to the first DC/DC converter, so as to cause the energy storage battery to receive, at the first voltage via the first DC/DC converter, electrical energy released by the traction battery.