Active-Clamp DC-DC Converter for Wide-Range Isolated Power Transfer
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Solution Overview
Problem
Existing DC-DC voltage converters struggle to efficiently transfer power between high-voltage and low-voltage grids in electric vehicles, particularly with increasing battery capacities and output voltages, while ensuring sufficient dielectric strength and cost-effectiveness.
Innovation Solution
A DC-DC voltage converter with a simple circuit topology that includes a transformer, switching elements, and a capacitor, capable of converting input DC voltage to a predefined output DC voltage over a wide input voltage range, ensuring sufficient dielectric strength and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional DC-DC voltage converter topologies are used to transfer power between high-voltage and low-voltage grids, then power transfer capability is achieved, but circuit complexity increases and cost rises
Solution Approach 1:
The converter circuit is segmented into distinct functional modules: a high-voltage side switching network with four switching elements (S1-S4) and a low-voltage side bridge circuit with two switching elements (S5-S6), separated by a transformer. This modular segmentation allows each module to be optimized independently while maintaining overall system simplicity and reducing total component count compared to conventional topologies.
Solution Approach 2:
The switching elements serve multiple functions: S1 and S2 on the high-voltage side perform both power switching and voltage clamping functions, while S5 and S6 on the low-voltage side simultaneously execute rectification and voltage regulation. This multi-functionality reduces the need for separate dedicated components, thereby simplifying the overall circuit topology.
2Device complexity
If the number of switching elements is reduced to simplify the circuit, then device complexity decreases, but the ability to handle high input voltages with sufficient dielectric strength deteriorates
Solution Approach 1:
A transformer is introduced as an intermediary component between the high-voltage input and the low-voltage output circuits. The transformer provides galvanic isolation and voltage transformation, enabling the use of lower-voltage-rated switching elements on the low-voltage side while safely handling high input voltages on the primary side, thus maintaining dielectric strength requirements without excessive component count.
Solution Approach 2:
The circuit employs active clamping mechanisms that dynamically adjust voltage distribution across switching elements during operation. By controlling the switching timing and duty cycles of S1-S6, the voltage stress on each switching element is optimized to remain within their dielectric strength ratings, even when processing high input voltages, thereby allowing reduction in the number of switching elements required.
3Ease of manufacture
If a simple circuit topology is used to reduce cost and installation space, then ease of manufacture and space efficiency improve, but the ability to operate over wide input voltage ranges deteriorates
Solution Approach 1:
The converter employs dynamic control of the switching elements S1-S6, where the duty cycles and switching frequencies are continuously adjusted based on the input voltage level. This dynamic operation enables the same simple circuit topology to adapt to a wide range of input voltages, maintaining efficient power conversion across varying battery charge states without requiring multiple fixed-topology circuits.
Solution Approach 2:
The control system modifies operating parameters including switching frequency and duty ratio in response to input voltage changes. When input voltage increases, the controller adjusts the switching parameters to maintain optimal power transfer and prevent over-voltage conditions, thereby enabling the simple circuit to operate effectively across wide voltage ranges suitable for evolving battery capacities.
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 proposed DC-DC voltage converter effectively transfers power between high-voltage and low-voltage grids with reduced power loss and increased efficiency, while maintaining sufficient dielectric strength and being cost-effective and space-efficient.
Implementation Method 1
The transformer has a primary side and a secondary side. A first connection of the primary side of the transformer is connected to a first connection element of the first input connection.
Implementation Method 2
A first connection of the capacitor is connected to the node. A second connection of the capacitor is connected to the second connection of the primary side of the transformer.
Data Source
AI summary
The invention relates to a DC voltage converter for transferring power from a high voltage network to a low voltage network. As a result, a circuit configuration which can be operated alternatively as an active-clamp flyback converter or an active-clamp buck converter is used.