Multi-Phase Resonant Converter With Tuned Tanks for Soft Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing single-stage three-phase isolated converters require high-voltage bidirectional switch devices and often feature complex control concepts or fixed output voltages, leading to inefficiencies due to constant current stress across all phases, even during low power delivery.
Innovation Solution
A multi-phase resonant power converter with a single primary-side power stage, utilizing bridge converter legs, a transformer device, and separate resonant tanks tuned to within ±50% of the switching frequency, allowing for efficient power conversion and reduced switch device stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-stage three-phase isolated converters use high-voltage bidirectional switch devices (1200V), then isolation and power conversion are achieved, but device complexity and cost increase
Solution Approach 1:
The power converter is divided into multiple independent phases, each with its own resonant tank and switch devices. This segmentation allows each phase to operate independently with lower-voltage switches (600V/650V) instead of requiring high-voltage (1200V) bidirectional switches, thereby reducing device complexity while maintaining isolation capability
Solution Approach 2:
A resonant tank is introduced as an intermediary element between the switch devices and the transformer. This resonant tank enables soft switching operation, allowing the use of lower-voltage switch devices while achieving the required isolation and power conversion functions
2Device complexity
If phase-modular solutions use 600V/650V bidirectional switch devices, then device complexity is reduced, but the number of switch devices increases to 3×4
Solution Approach 1:
Each phase is segmented into its own resonant tank with dedicated switch devices, allowing independent operation. This segmentation enables the use of fewer, lower-voltage switches per phase rather than requiring multiple high-voltage bidirectional switches, reducing the total component count while maintaining the desired voltage rating reduction
3Power
If current circulating through transformers and switches is determined by the highest grid phase current, then power conversion is maintained, but efficiency decreases during low power delivery
Solution Approach 1:
The resonant frequency of each tank is tuned to match the switching frequency, enabling dynamic soft switching operation. This allows the current through each phase's transformer and switches to dynamically track the actual power delivery requirements of that phase, rather than being constrained by the maximum current of any single phase, thereby improving efficiency during low power delivery
Solution Approach 2:
The resonant tanks operate at a switching frequency that is synchronized with the resonant frequency, creating periodic soft switching cycles. This periodic operation allows each phase to efficiently handle only its own power delivery requirements, reducing unnecessary current circulation and improving overall system efficiency during varying load conditions
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 solution achieves high-frequency isolation, supports zero-voltage switching, enables bidirectional power flow, and provides efficient power conversion with reduced control complexity and lower-rated switch devices, improving overall efficiency and interoperability.
Implementation Method 1
a separate resonant tank electrically connected to a midpoint of each bridge converter leg of the power stage, each resonant tank comprising a resonant capacitor in series with the primary side winding for that bridge converter leg, wherein a resonant frequency of each resonant tank is tuned to within +/−50% of the switching frequency
Implementation Method 2
a transformer device having a primary side winding for each bridge converter leg of the power stage, and a secondary side winding for each primary side winding
Data Source
AI summary
A multi-phase resonant power converter includes: a power stage on a primary side of the multi-phase resonant power converter, the power stage including bridge converter legs each configured to receive an AC input voltage and implement a separate phase of the power converter; a transformer device having a primary side winding for each bridge converter leg and a secondary side winding for each primary side winding; a power circuit electrically connected to the secondary side windings on a secondary side of the multi-phase resonant power converter; a primary-side controller configured to operate the bridge converter legs at a switching frequency; and a separate resonant tank electrically connected to a midpoint of each bridge converter leg. Each resonant tank includes a resonant capacitor in series with the primary side winding for that bridge converter leg. A resonant frequency of each resonant tank is tuned to within +/−50% of the switching frequency.