Shared-Transformer Charging Circuit for Low- and High-Voltage Batteries
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Solution Overview
Problem
Existing integrated battery charging circuits for low and high voltages often rely on transformers to reduce volume and cost, but this results in decreased performance, reliability, and efficiency, making mass production challenging.
Innovation Solution
A unitary charging device that shares one leg of a switching element of an isolated DC-DC converter between the secondary side of a high voltage transformer and the primary side of a low voltage transformer, reducing the number of switching elements and gate drivers, and utilizing a shared EMI filter and input capacitor to enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If a transformer is integrated into the charging circuit to reduce volume, then the system volume and price are reduced, but performance, reliability, and efficiency are lowered
Solution Approach 1:
The patent divides the integrated transformer into separate high-voltage and low-voltage transformers, allowing each to be optimized independently for reliability and efficiency while maintaining compact overall system volume through shared magnetic components and integrated circuit architecture
Solution Approach 2:
The patent implements nested magnetic components where the low-voltage transformer is positioned within or adjacent to the high-voltage transformer structure, enabling space-efficient arrangement that reduces overall system volume while maintaining the reliability benefits of separate transformer windings
2Volume of stationary object
If the transformer is provided as one unit to reduce volume, then the system volume is reduced, but the reliability and ease of industrial application are reduced
Solution Approach 1:
The patent segments the transformer assembly into distinct high-voltage and low-voltage sections with separate windings and magnetic paths, enabling modular manufacturing and assembly processes that improve ease of industrial application while maintaining compact volume through integrated mounting structures
3Reliability
If separate charging circuits are used for high voltage and low voltage batteries, then performance and reliability are maintained, but volume and weight increase
Solution Approach 1:
The patent merges separate high-voltage and low-voltage charging circuits into a unified architecture that shares common components including the DC link, control circuitry, and magnetic elements, thereby reducing overall charger volume and weight while maintaining the reliability of independent charging paths through isolated transformer windings
Solution Approach 2:
The patent creates multi-functional circuit elements that serve both high-voltage and low-voltage charging functions, such as the DC link that supplies both battery types and the integrated transformer structure that provides isolation for both voltage levels, reducing the need for duplicate 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 solution reduces the number of switching elements and gate drivers, improving reliability and performance while reducing conduction and switching losses, thereby decreasing the price and volume of the charging device and enhancing overall efficiency.
Implementation Method 1
a DC-DC converter connected to a secondary side of the high voltage transformer and configured to convert an output signal of the high voltage transformer into a DC voltage
Implementation Method 2
a low voltage transformer connected to an opposite end of the DC-DC converter and configured to perform a phase shift of the DC voltage of the DC-DC converter and perform a step-down of the DC voltage
Implementation Method 3
a resonance converter configured to allow the DC link voltage connected to an output end of the DC link to be resonated and to transfer an output signal of a resonance frequency
Data Source
AI summary
Disclosed is a unitary charging device for low and high voltages. According to a specific embodiment, one leg of a switching element of an insulated DC-DC converter, the secondary side of a high voltage transformer, and the primary side of a low voltage transformer are shared, and thus the number of switching elements of the charging device and gate drivers for operating the multiple switching elements can be reduced, reliability is improved, and the performance of the unitary charging device can improve even when the number of switching elements is reduced. Due to the shared use of an EMI filter and an input capacitor of a high voltage battery, not only can the price and volume of the charging device be decreased, but conduction loss and switching loss can also be reduced to increase efficiency.