Bidirectional DC-DC Converter Topology Switching for Wide Voltage Ranges
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Solution Overview
Problem
Existing bidirectional DC-to-DC converters in automotive on-board charging systems for electric vehicles face inefficiencies due to varying voltage and power levels, leading to unwanted low-efficiency operating zones, especially when adapting to different loads like high-voltage batteries.
Innovation Solution
A bidirectional DC-to-DC converter with a control unit that dynamically switches between high power, low power, and transition configurations by adjusting the transformer stage's topology and transformation ratio, utilizing an LLC, DAB, and CLLLC topologies, and varying the primary and secondary circuit components to maintain efficiency across a wide range of input and output voltages and powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the converter uses a fixed topology design, then the structure is simple, but the efficiency drops significantly when voltage and power levels vary
Solution Approach 1:
The patent implements dynamic topology switching by controlling switches (S1-S4) to reconfigure the converter circuit between different operational modes (full-bridge, half-bridge, direct connection) based on real-time voltage and power conditions. This dynamic adaptation allows the converter to maintain optimal efficiency across varying operating conditions while managing structural complexity through controlled reconfiguration.
2Adaptability or versatility
If the converter partitions component sizes to adapt to different loads, then the adaptability improves, but the device complexity increases
Solution Approach 1:
The patent achieves multi-functionality by designing a single converter circuit that can operate in multiple modes: full-bridge rectification for high power applications, half-bridge for medium power, and direct connection for low power scenarios. The same physical components (transformer, capacitors, inductors) serve different functional roles based on switch configuration, eliminating the need for separate circuits for each power level and reducing overall complexity.
Solution Approach 2:
The converter is segmented into modular functional blocks (switching network, transformer, rectifier, filter) that can be independently controlled and reconfigured. By dividing the circuit into controllable segments with switches at strategic points, the system can activate or deactivate specific segments based on power requirements, enabling flexible adaptation without requiring complete circuit redesign for each scenario.
3Adaptability or versatility
If the converter operates in sensitive voltage variation zones, then the versatility increases, but unwanted low-efficiency operating zones are introduced
Solution Approach 1:
The control unit continuously monitors input voltage levels and power conditions, then provides feedback to adjust switch configurations accordingly. When voltage drops into sensitive zones, the system detects this and transitions to appropriate operating modes (e.g., from full-bridge to half-bridge or direct connection), preventing operation in inefficient zones while maintaining versatility across the full voltage range through active monitoring and adaptive response.
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 solution enables the converter to maintain high efficiency and versatility, adapting to changing power and voltage conditions, thus optimizing the operational point and broadening its application in electric and hybrid vehicles, particularly during charging where voltage can vary by a 2:1 ratio.
Implementation Method 1
The transformer stage (4) is provided with a primary circuit (5) and a secondary circuit (6) equipped with, respectively, a primary winding (7) and a secondary winding (8), which can be magnetically coupled
Data Source
AI summary
A bidirectional DC-to-DC converter includes first terminals connected to a direct current source, second terminals connected to a load that can be supplied with direct current, a transformer stage including a primary and a secondary circuit that can be magnetically coupled to each other, a switching stage operatively interposed between the two first terminals and the primary circuit and a rectifier stage operatively interposed between the two second terminals and the secondary circuit. A control unit is configured to drive the switching stage and the rectifier stage. The control unit is configured to switch a first switch of the primary circuit and a second switch of the secondary circuit between an open and a closed condition as a function of the level of power transferred by the transformer stage and/or the direction of the energy flow, to change the topology of the primary circuit and/or the secondary circuit.