Parallel Power Converter Current Allocation for Efficiency
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Solution Overview
Problem
Conventional electrified vehicles with a single power converter for transferring energy from a high-voltage electrical bus to a low-voltage electrical bus face inefficiencies at lower current levels, leading to reduced energy economy and increased heat generation, as the converter efficiency decreases significantly when current demands are low.
Innovation Solution
A system with multiple power converters arranged in parallel, where a controller allocates current demand based on the state of charge of battery cells, redistributes currents to maintain efficiency by operating subsets of converters above a threshold, and adjusts current magnitudes to ensure total current provision remains consistent before and after redistribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single power converter is used to transfer energy from high-voltage bus to low-voltage bus, then device complexity is reduced, but converter efficiency deteriorates significantly when current demands are low
Solution Approach 1:
The patent divides the single power converter into multiple parallel power converters. Each converter handles a portion of the total current demand, allowing individual converters to operate within their optimal efficiency ranges even at lower current levels. This segmentation resolves the contradiction by maintaining energy efficiency without significantly increasing overall system complexity.
Solution Approach 2:
The patent implements dynamic current allocation where the controller continuously adjusts the current distribution among parallel converters based on real-time operating conditions. This dynamic adjustment ensures that converters operate at optimal efficiency points across varying current demands, resolving the efficiency deterioration problem while maintaining manageable device complexity through intelligent control.
2Loss of energy
If current is allocated to multiple power converters in parallel, then converter efficiency is maintained across varying current demands, but device complexity increases
Solution Approach 1:
The patent merges multiple parallel power converters into a unified system with centralized control. The controller manages current allocation across all converters as an integrated system, allowing the benefits of multiple converters (maintained efficiency) to be realized while presenting a simplified interface and control structure that mitigates the perceived complexity increase.
Solution Approach 2:
The parallel converter system is designed with universal control logic that can adapt to various operating conditions and current demands. The same control architecture manages all converters regardless of the specific operating point, reducing the complexity burden by providing a multi-functional, adaptable control system rather than requiring specialized control for each converter.
3Use of energy by moving object
If current demand is low, then energy consumption is reduced, but converter efficiency decreases significantly leading to increased heat generation
Solution Approach 1:
By segmenting the total current among multiple parallel converters, each converter processes a smaller current portion that keeps it within its optimal efficiency range. This prevents the efficiency drop and associated heat generation that would occur in a single converter handling low current demands, while still achieving the overall energy reduction goal.
Solution Approach 2:
The patent converts the potential harm of low current operation (efficiency deterioration and heat generation) into a benefit by using the low current demand condition to activate only the necessary number of converters or to allocate current in a way that maintains optimal efficiency. The low demand condition becomes an opportunity to optimize the converter configuration rather than a problem.
Data Source
AI summary
A vehicle includes a traction battery comprising a plurality of cells. The vehicle also includes a plurality of power converters each electrically coupled between a corresponding group of cells and an electrical bus. A controller is programmed to allocate current demand to the power converters and operate the power converters to minimize energy consumption and losses.