Series DC-DC Converter Architecture for Modular Battery Voltage Boost
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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, leading to high costs, large components, and limited flexibility in module management and replacement.
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, reducing the need for costly silicon carbide switches and enabling flexible module management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single high-voltage DC-DC converter is used to convert 400V battery output to 700-800V DC link voltage, then the voltage conversion function is achieved, but the converter becomes large, expensive, and requires costly silicon carbide switches
Solution Approach 1:
The patent divides the single high-voltage conversion function into multiple lower-voltage conversion stages. Each DC-DC converter handles a portion of the voltage conversion task, converting from module voltage (e.g., 50V) to an intermediate voltage level. Multiple converters are connected in series at the output to achieve the total required DC link voltage (700-800V). This segmentation allows use of cheaper, lower-voltage rated switches and reduces the size and cost of each individual converter while maintaining the overall power conversion capability.
2Power
If battery modules are connected in series to increase voltage output, then the voltage matches the DC link requirement, but the system loses flexibility in module management and replacement
Solution Approach 1:
The patent maintains physical segmentation of battery modules while adding functional segmentation through individual DC-DC converters for each module. Each converter is independently controllable and can manage its associated module separately. This allows individual module replacement, reconfiguration, or maintenance without affecting the entire battery pack, thereby maintaining management flexibility while achieving the required output voltage through series connection of converter outputs.
Solution Approach 2:
The system dynamically manages battery modules through independent control of each DC-DC converter. The converters can be selectively enabled or disabled based on module availability, health status, or operational requirements. This dynamic management capability allows the system to adapt to different operational scenarios, module failures, or replacement scenarios while maintaining the required voltage output through the series-connected converter architecture.
3Adaptability or versatility
If individual DC-DC converters are used for each battery module, then module management flexibility and cell balancing are improved, but the number of converters increases
Solution Approach 1:
While the patent does implement individual DC-DC converters for each battery module (increasing the number of converters), this segmentation enables critical functions: independent module management, individual cell balancing within each module, and selective operation of specific modules. The benefits of enhanced adaptability, maintenance flexibility, and battery health management outweigh the increase in converter quantity, as each converter is relatively simple compared to a single high-voltage converter and enables sophisticated battery pack management.
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 solution reduces costs, eliminates the need for pre-charge resistors, allows for efficient cell balancing, and enables modular replacement and upgrade of battery packs, enhancing flexibility and management capabilities.
Implementation Method 1
each of the plurality of DC-DC converters is operative to convert a DC input voltage of a first magnitude to a DC output voltage of a second magnitude
Data Source
AI summary
An electrical power distribution system supplies electrical power from a battery pack to a DC link. The battery pack includes a plurality of modules. The system includes a plurality of DC-DC converters. Outputs of the DC-DC converters are coupled in series between a first output node and a second output node of the system, such that an output voltage of the system is equal to a sum of output voltages of the DC-DC converters. In use, each of the DC-DC converters is coupled to one of the modules to receive a DC input voltage of a first magnitude from the respective module. Each of the DC-DC converters is operative to generate an output voltage of a second magnitude. The first output node is coupled to a first input terminal of the DC link and the second output node is coupled to a second input terminal of the DC link.