Bidirectional Non-Isolated DC-DC Topology for Circulating Current Suppression
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Solution Overview
Problem
Current bidirectional non-isolated DC-DC power supply topologies face issues such as fixed boost/buck direction, direct conductive paths causing circulating currents, and high voltage stress on components, making them unsuitable for high-voltage designs and multi-module parallel configurations.
Innovation Solution
A bidirectional non-isolated DC-DC topology control circuit with a capacitor midpoint connection and a drive control module that employs interleaved and synchronous wave-emitting control modes to manage switch transistors, ensuring balanced voltage stress and preventing circulating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct conductive path exists between input and output terminals in non-isolated DC-DC topology, then circuit simplicity is improved, but circulating currents cannot be suppressed when multiple modules are connected in parallel
Solution Approach 1:
The patent segments the direct conductive path by introducing a common neutral point connection through capacitor midpoints. This segmentation prevents the formation of direct circulating current paths between parallel modules while maintaining circuit simplicity, as the neutral point acts as a common reference without creating harmful current loops.
Solution Approach 2:
The common neutral point serves as an intermediary element that connects multiple parallel modules without creating direct conductive paths between their input and output terminals. This mediator allows voltage balancing and provides a reference point while preventing circulating currents from flowing between modules.
2Device complexity
If boost/buck direction is fixed in non-isolated DC-DC topology, then circuit structure is simplified, but adaptability to different voltage conversion directions is reduced
Solution Approach 1:
The patent introduces dynamic control through four switch transistors that can be independently controlled to enable bidirectional operation. The circuit transitions from a fixed topology to a dynamically controllable one, where the switch states determine whether boost or buck conversion occurs, allowing the same circuit to adapt to different voltage conversion directions.
Solution Approach 2:
The circuit achieves multi-functionality by incorporating four switch transistors that enable both boost and buck conversion modes within the same topology. The universal design allows the circuit to perform multiple functions (bidirectional voltage conversion) without requiring separate dedicated circuits for each direction.
3Device complexity
If voltage stress on individual components is high in non-isolated DC-DC topology, then component count is reduced, but suitability for high-voltage input/output designs is compromised
Solution Approach 1:
The patent segments the voltage stress by introducing a common neutral point that divides the voltage distribution. Each switch transistor and capacitor experiences reduced voltage stress because the neutral point creates balanced voltage divisions across the circuit components, making the topology suitable for high-voltage applications.
Solution Approach 2:
The circuit implements local quality optimization by distributing voltage stress differently across various components through the neutral point connection. Each component is positioned and configured to experience appropriate voltage levels, with the neutral point ensuring that no single component bears excessive voltage stress.
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 2
AI summary
A bidirectional non-isolated direct current to direct current (DC-DC) topology control circuit and a related apparatus are provided in embodiments of the disclosure. The bidirectional non-isolated DC-DC topology control circuit includes a bidirectional non-isolated DC-DC topology circuit. The bidirectional non-isolated DC-DC topology circuit includes an input voltage, a first switch transistor, a second switch transistor, a third switch transistor, a fourth switch transistor, a first input capacitor, a second input capacitor, a first output capacitor, a second output capacitor, a first energy-storage inductor, a second energy-storage inductor, and an output voltage. Compared to the non-isolated DC-DC power supply topologies in practical applications, this topology circuit can achieve both boost and buck functions while ensuring balanced voltage stress across switch components. By designing a capacitor midpoint connection between input and output, circulating current in multi-module parallel configurations may be effectively solved.