Three-Phase Bidirectional AC-DC Converter With Shared Secondary ZVS
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Solution Overview
Problem
Conventional phase modular single-stage AC-DC power supplies have high component counts and costs due to the need for independent control of three individual phases, leading to increased complexity and loss of zero-voltage-switching (ZVS) in primary or secondary switches.
Innovation Solution
A bidirectional AC-DC power supply design with a plurality of primary circuits, transformers, and a control circuit that ensures zero-voltage-switching by controlling phase shifts of switches, reducing the component count to include a single resonant tank and one rectifier stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional phase modular single-stage AC-DC power supplies use independent control of three individual phases, then each phase can be controlled independently, but the component count and cost increase significantly
Solution Approach 1:
The patent merges three separate single-phase AC-DC power supplies into a single integrated three-phase power supply. The three primary circuits share a common secondary circuit, resonant tank, and rectifier stage, significantly reducing component count while maintaining independent phase control capability through the control circuit that adjusts phase shifts between primary circuits.
Solution Approach 2:
The secondary circuit and resonant tank serve multiple functions simultaneously - they are shared by all three primary circuits (phases). This multi-functional design allows the same components to handle power from multiple phases, reducing overall component requirements while maintaining the ability to independently control each phase.
2Adaptability or versatility
If conventional phase modular single-stage AC-DC power supplies use multiple secondary rectifier stages, then each phase can be rectified independently, but the component count and cost increase
Solution Approach 1:
The patent combines three separate secondary rectifier stages into a single shared rectifier stage. The common secondary circuit and rectifier stage process power from all three phases simultaneously, significantly reducing component count while maintaining the ability to independently control rectification for each phase through phase shift adjustment.
3Device complexity
If conventional LLC based power supplies combine all secondary rectifier stages into one, then component count and cost are reduced, but phase synchronization is lost and ZVS cannot be maintained
Solution Approach 1:
The patent employs dynamic phase shift control to maintain zero-voltage-switching in the integrated architecture. The control circuit dynamically adjusts the phase shifts between the three primary circuits based on load conditions and synchronization requirements, enabling ZVS to be maintained across all switches despite the integrated design.
Solution Approach 2:
The control circuit uses feedback mechanisms to monitor and maintain phase synchronization and zero-voltage conditions. By continuously adjusting phase shifts based on system state, the control circuit ensures ZVS is maintained while operating with the reduced component count architecture.
4Adaptability or versatility
If independent control of three phases is implemented, then each phase can be optimized independently, but the control implementation becomes more complex
Solution Approach 1:
The patent segments the control of each phase while integrating the power processing. Each primary circuit can be independently controlled through phase shift adjustment, allowing independent optimization, while the shared secondary circuit provides integration. The control circuit manages phase shifts for each phase separately, simplifying the control implementation compared to fully independent designs.
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 design achieves significant reduction in component count and cost while ensuring zero-voltage-switching across all switches, maintaining efficiency and flexibility in voltage and power conversion.
Implementation Method 1
The control circuit is configured to control switches of the plurality of primary circuits and the secondary circuit to switch under zero voltage by controlling phase shifts of the switches of the plurality of primary circuits
Implementation Method 2
The plurality of transformers are electrically connected to the plurality of primary circuits respectively. A primary winding of each transformer is coupled to a corresponding one of the plurality of primary circuits, and a plurality of secondary windings of the plurality of transformers are electrically connected in series
Data Source
Figure 1
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Figure 3A
AI summary
A bidirectional AC-DC power supply (100) is provided. The bidirectional AC-DC power supply (100) includes a plurality of primary circuits (11, 12, 13), a plurality of transformers (TR1, TR2, TR3), one secondary circuit (2) and a control circuit (3). The plurality of primary circuits (11, 12, 13) are electrically connected to a plurality of phase voltages (V1, V2, V3) of an AC power respectively. The plurality of transformers (TR1, TR2, TR3) are electrically connected to the plurality of primary circuits (11, 12, 13) respectively. A primary winding of each transformer (TR1) is coupled to a corresponding one of the plurality of primary circuits (11), and a plurality of secondary windings of the plurality of transformers (TR1, TR2, TR3) are electrically connected in series. The secondary circuit (2) is electrically connected to the plurality of secondary windings of the plurality of transformers (TR1, TR2, TR3). The control circuit (3) is configured to control switches of the plurality of primary circuits (11, 12, 13) and the secondary circuit (2) to switch under zero voltage by controlling phase shifts of the switches of the plurality of primary circuits (11, 12, 13).