Three-Phase LLC Circuit With Star-Connected Secondaries
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Solution Overview
Problem
Three-phase LLC power converters face challenges with high switching currents and voltage stresses, leading to large and expensive components due to the need for robust inductor/transformer pairs.
Innovation Solution
A three-phase power supply circuit is designed with three LLC resonant voltage convertors, each coupled with a step-down transformer, and a bridge rectifier, where the secondary coils of the transformers are electrically coupled in a star formation, reducing switching current, voltage stress, and transformer primary RMS currents, thereby improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional three-phase LLC power converters use robust inductor/transformer pairs to withstand large switching currents and voltage stresses, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent divides the three-phase power converter into three separate single-phase LLC resonant voltage converters, each handling one phase independently. This segmentation allows each phase to use smaller, less expensive inductors and transformers while maintaining overall system reliability through distributed processing of switching currents and voltage stresses.
Solution Approach 2:
The patent combines three single-phase LLC resonant voltage converters into a unified three-phase system with a common output capacitor and control architecture. This merging achieves the benefits of reduced component size per phase while maintaining the reliability of a three-phase system through coordinated operation of all three phases.
2Reliability
If traditional three-phase LLC power converters use large inductor/transformer pairs, then voltage stress resistance is improved, but energy efficiency deteriorates due to higher RMS currents
Solution Approach 1:
By segmenting the three-phase system into three independent single-phase LLC resonant converters, each converter processes only one-third of the total power load. This reduces the RMS current in each transformer primary winding, decreasing copper losses and improving overall energy efficiency while maintaining voltage stress resistance through the resonant circuit design.
Solution Approach 2:
The patent changes the operating parameters of each single-phase converter to optimize for reduced RMS currents. The resonant frequency and switching frequency are tuned to minimize losses, and the output voltage is regulated to achieve optimal efficiency at the reduced current levels while still withstanding the required voltage stresses.
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
This configuration results in reduced switching current, voltage stress, and transformer primary RMS currents, enhancing the efficiency and cost-effectiveness of the power supply circuit.
Implementation Method 1
three LLC resonant voltage convertors
Implementation Method 2
three step-down transformers. Each step-down transformer includes a primary and secondary coil
Implementation Method 3
a bridge rectifier. The bridge rectifier is electrically coupled with the first node of the secondary coil of each of the three step-down transformers
Data Source
AI summary
A three-phase power supply circuit is provided. The power supply circuit includes three LLC resonant voltage convertors, three step-down transformers, and a bridge rectifier. Each step-down transformer includes a primary and secondary coil, and each primary and secondary coil has a first node and a second node. Each step-down transformer is electrically coupled with one of the three LLC resonant voltage convertors by the first and second nodes of the primary coils. The bridge rectifier is electrically coupled with the first node of the secondary coil of each of the three step-down transformers. The second nodes of the secondary coils of each of the three step-down transformers are electrically coupled together.