Three-Phase Delta Resonant Converter Topology for Power Density
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Solution Overview
Problem
Resonant DC to DC converters, such as LLC converters, face challenges with high AC currents in output capacitors leading to increased power losses and large size requirements for filter components, necessitating improved topologies for better efficiency and reduced noise from smaller packages.
Innovation Solution
A three-phase resonant DC to DC converter topology featuring a delta circuit with inner and outer resonant devices strategically located to enhance zero voltage switching performance, incorporating transformers and inductors in a configuration that allows for improved power density and reduced size, while maintaining galvanic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If LLC resonant converter topology is used, then high efficiency is achieved through soft switching, but high AC currents in output capacitors result in increased power losses
Solution Approach 1:
The patent divides the resonant tank into separate primary and secondary sides with multiple capacitors on the primary side (C1, C2, C3) and multiple inductors on the secondary side (L1, L2, L3). This segmentation allows the AC current to be distributed across multiple capacitors rather than flowing through a single output capacitor, reducing the RMS current and associated power losses in each individual capacitor.
Solution Approach 2:
The patent introduces a three-phase architecture with three distinct phases (Phase A, Phase B, Phase C), each with its own resonant tank and switching devices. This dimensional expansion from single-phase to three-phase allows the total power transfer to be distributed across three parallel paths, significantly reducing the current stress on each output capacitor while maintaining high efficiency through soft switching.
2Volume of stationary object
If LLC resonant converter topology is used, then galvanic isolation is provided, but large volume is required for output filter components
Solution Approach 1:
The three-phase architecture allows the use of smaller individual capacitors and inductors compared to a single-phase design delivering the same total power. The volumetric requirements are distributed across three phases, and the interleaved operation reduces the ripple current that would otherwise require large filter components. This dimensional expansion enables compact design while maintaining galvanic isolation through the transformer.
Solution Approach 2:
The patent changes the operating parameters by using multiple capacitors in parallel on the primary side and multiple inductors in parallel on the secondary side. This parameter change allows the same power transfer function to be achieved with smaller individual components, reducing the overall volume required for output filter components while maintaining the galvanic isolation provided by the transformer.
3Object-generated harmful factors
If multiple LLC converters are paralleled with interleaved PWM, then output ripple current is reduced, but device complexity increases
Solution Approach 1:
The patent merges three separate resonant converter phases into a single integrated three-phase resonant converter topology. The three phases share common components such as the resonant frequency determination and control architecture, while maintaining galvanic isolation through the transformer. This unified approach achieves reduced output ripple current through interleaved operation but with less complexity than paralleling three independent LLC converters, as the phases are inherently synchronized through the common resonant tank design.
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 topology enhances zero voltage switching efficiency and power density, reducing power losses and size requirements, thereby achieving better efficiency and lower noise from smaller packages compared to traditional resonant converters.
Implementation Method 1
Resonant DC to DC converters are considered by many to be attractive power conversion solutions... Following a resonant tank with transformers provides galvanic isolation... Resonant converters also have inherent properties, such as soft switching of the semiconductor switches, which lead to high efficiency and low noise.
Implementation Method 2
Following a resonant tank with transformers provides galvanic isolation which is important for level conversion as well as for safety.
Data Source
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AI summary
A resonant circuit includes first, second, and third input nodes configured to receive a three phase input power. The resonant circuit is formed as a delta circuit including a first leg connected between a first comer node and a second comer node, a second leg connected between the second comer node and a third comer node, and a third leg connected between the third comer node and the first comer node. A first outer resonant device is connected between the first input node and the first comer node, a second outer resonant device connected between the second input node and the second comer node, and a third outer resonant device connected between the third input node and the third comer node. Each leg of the delta circuit includes an inner resonant device connected in series with a corresponding transformer.