DC-DC Converter Circulating Current Reduction
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Solution Overview
Problem
Existing DC-DC converters with multiple windings suffer from high power loss due to circulating currents, which are not effectively managed, especially in three-directional configurations where the secondary full bridge circuit becomes unfixed and experiences increased circulating currents, leading to inefficiencies in power transfer.
Innovation Solution
A DC-DC converter design incorporating a k-th order converter with a reactor and semiconductor switching elements, capacitors, and a transformer with an N-th order winding, where a controller manages switching operations to minimize circulating currents by controlling the on-period of semiconductor switching elements and adjusting output power through phase differences and duty cycles, specifically setting the primary converter as either an input or output converter and controlling secondary and tertiary converters to reduce power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the phase difference between the switching of the primary full bridge circuit and the switching of the secondary full bridge circuit is increased to transfer power from primary to secondary side, then power transfer capability is improved, but the circulating current in the tertiary winding increases significantly, leading to increased power loss
Solution Approach 1:
The patent applies dynamics by making the role of each full bridge circuit dynamic rather than fixed. The controller dynamically determines whether each full bridge circuit (primary, secondary, or tertiary) acts as an input converter or output converter based on real-time power transfer requirements. This dynamic role assignment allows the system to optimize power transfer paths and minimize circulating currents by always designating one full bridge circuit as the input converter that receives power from the DC power supply, thereby resolving the contradiction between power transfer capability and power loss.
2Adaptability or versatility
If the secondary full bridge circuit is allowed to become unfixed (既能作为输入侧又能作为输出侧), then adaptability of the converter is improved, but the circulating current increases due to the secondary circuit receiving and transferring power simultaneously
Solution Approach 1:
The patent applies self-service by enabling each full bridge circuit to autonomously determine its operational role based on system conditions. The controller monitors the states of all full bridge circuits and automatically designates the most appropriate one as the input converter, allowing the system to self-optimize without external intervention. This self-service mechanism maintains high adaptability while preventing excessive circulating currents by ensuring one circuit always serves as the primary power reception point.
3Adaptability or versatility
If multiple full bridge circuits are configured to transfer power in multiple directions, then versatility of the converter is improved, but the complexity of controlling switching operations increases
Solution Approach 1:
The patent applies universality by designing all full bridge circuits with identical structures and capabilities, allowing each circuit to perform both input and output functions. This multi-functionality design simplifies control complexity because the same control logic can be applied to any full bridge circuit regardless of its current role. The controller uses a unified control strategy that dynamically assigns roles based on system needs, rather than requiring separate control mechanisms for different circuit configurations.
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 solution effectively restricts the amplitude of circulating currents, reducing power loss and ensuring efficient power transfer by dynamically controlling the switching operations across the primary, secondary, and tertiary converters, thereby enhancing the overall efficiency of the DC-DC converter.
Implementation Method 1
a transformer having a primary winding through an N-th order winding
Implementation Method 2
a k-th order converter including a reactor
Data Source
AI summary
A direct current to direct current (DC-DC) converter includes a k-th order converter including a reactor, multiple semiconductor switching elements, and multiple capacitors respectively connected in parallel with the semiconductor switching elements (k is a natural number equal to or below N and N is a natural number equal to or above 3), a transformer having a primary winding through an N-th order winding, and a controller that controls switching of a primary converter through an N-th order converter.