Series DC-DC Converter Architecture for Modular Battery Packs
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Solution Overview
Problem
Existing electrical power distribution systems for transport refrigeration units face challenges in efficiently converting battery pack voltage to high DC voltage requirements, necessitating large and costly components, and are limited by the weakest module or cell, lacking flexibility and efficiency in voltage and current management.
Innovation Solution
A system comprising a series connection of DC-DC converters and module management units (MMUs) that monitor and balance cell parameters, allowing individual control of each converter to achieve a predefined output voltage and current, eliminating the need for costly silicon carbide switches and reducing reliance on the weakest module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single DC-DC converter is used to convert battery voltage to high DC voltage, then the conversion function is achieved, but the converter becomes large and costly requiring silicon carbide switches
Solution Approach 1:
The patent divides a single high-power DC-DC converter into multiple lower-power DC-DC converters connected in series. Each converter handles a portion of the total voltage conversion task, allowing the use of conventional, cost-effective components instead of expensive silicon carbide switches required for a single high-voltage converter.
Solution Approach 2:
The patent combines multiple DC-DC converters in series to achieve the required high output voltage. The individual converters are merged electrically through series connection, where their output voltages add up to meet the DC link voltage requirement, while each converter remains a separate, manageable unit.
2Reliability
If the system relies on the weakest module or cell, then system reliability is maintained, but flexibility and efficiency in voltage and current management are reduced
Solution Approach 1:
The battery pack is divided into multiple independent modules, each with its own DC-DC converter. This segmentation allows each module to be managed independently through dedicated module management units, enabling flexible voltage and current control for each module rather than being constrained by the weakest module.
Solution Approach 2:
The system implements dynamic control where each DC-DC converter can independently adjust its output based on real-time module conditions. The module management units continuously monitor and adjust operating parameters, allowing the system to adapt to changing conditions and optimize performance rather than being limited by static, conservative design assumptions.
3Ease of manufacture
If conventional components are used for voltage conversion, then cost is reduced, but component size and weight increase
Solution Approach 1:
By segmenting the power conversion function across multiple smaller converters, each converter can use lighter, conventional components. The distributed architecture allows each unit to be optimized for lower power handling, reducing the weight of individual converters compared to a single large high-voltage converter.
Solution Approach 2:
The system changes the operating parameters of each converter by distributing the voltage conversion task. Each converter operates at lower voltage and power levels with conventional components, whereas a single converter would require high-voltage rated heavy-duty components. The series connection of multiple low-voltage converters achieves the same high output voltage without requiring heavy high-voltage components.
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
The system achieves efficient, cost-effective voltage conversion with reduced component size and weight, enabling flexible module replacement, improved monitoring, and independent current control, enhancing the overall performance and management of battery packs.
Implementation Method 1
each of the plurality of DC-DC converters is operative to generate, based on the received DC input voltage, an output voltage of a second magnitude
Data Source
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AI summary
An electrical power distribution system (400) configured to supply electrical power from a battery pack (420) to a DC link (130), wherein the battery pack (420) comprises a plurality of modules (422a - 422n), each module (422a - 422n) comprising a set of cells, the electrical power distribution system (400) comprising: a plurality of DC-DC converters (410a - 410n), wherein outputs of the plurality of DC-DC converters (410a - 410n) are coupled in series between a first output node (412)_and a second output node (414) of the electrical power distribution system (400), such that an output voltage of the electrical power distribution system (400) is equal to a sum of output voltages of the DC-DC converters (410a - 410n), and wherein, in use of the electrical power distribution system (400): each of the plurality of DC-DC converters (410a - 410n) is coupled to a respective one of the plurality of modules (422a - 422n) to receive a DC input voltage of a first magnitude from the respective one of the plurality of modules (422a - 422n); and each of the plurality of DC-DC converters (410a - 410n) is operative to generate, based on the received DC input voltage, an output voltage of a second magnitude; and the first output node (412) is coupled to a first input terminal of the DC link (130) and the second output node (414) is coupled to a second input terminal of the DC link (130).