Three-Phase Hybrid Converter With Coupling Inductance
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Solution Overview
Problem
Conventional three-phase converters with DC links face limitations in dynamic range, harmonic loading, and efficiency due to the lack of energy storage, leading to uneven semiconductor loading and increased costs, volume, and complexity.
Innovation Solution
A three-phase hybrid converter concept where energy and voltage sources are decoupled via a coupling inductance, allowing for a parallel hybrid converter configuration with reduced harmonic injection and improved voltage quality, enabling efficient operation without a central DC link and neutral conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional DC link converters are used, then bidirectional conversion of DC and three-phase AC voltages is achieved, but the device has larger volume, higher weight, and higher harmonic load
Solution Approach 1:
The converter is divided into two independent three-phase converter circuits (first and second) that are connected in parallel through a coupling unit. Each converter can be optimized for specific functions, allowing reduction of overall volume and harmonic content by distributing conversion tasks across segmented units rather than using a single large DC link converter
Solution Approach 2:
A coupling unit with coupling inductances is introduced as an intermediary between the two three-phase converter circuits. This coupling unit enables magnetic coupling and energy transfer without requiring a large central DC link, thereby reducing the overall converter volume while maintaining bidirectional conversion capability and reducing harmonic loads
2Device complexity
If direct inverters without energy storage are used, then the structure is simplified, but the output range is limited and harmonics are strongly coupled between input and output
Solution Approach 1:
The converter structure is segmented into two independent three-phase converter circuits connected through a coupling unit. This segmentation allows each converter to operate with reduced harmonic interaction, as the coupling inductances provide galvanic isolation and filter harmonic coupling between input and output sides while maintaining structural simplicity
Solution Approach 2:
The coupling unit with coupling inductances serves as an intermediary that decouples the harmonic content between input and output sides. The inductances act as natural filters that block high-frequency harmonic propagation while allowing fundamental power transfer, thus reducing harmonic coupling without adding complex filtering circuits
3Adaptability or versatility
If semiconductors are subjected to uneven stress due to frequency mismatch, then conversion is possible, but all semiconductors must be dimensioned larger increasing cost and complexity
Solution Approach 1:
The converter is segmented into two independent three-phase converter circuits, each capable of operating at different frequencies. This allows the first converter to handle high-frequency conversion tasks while the second handles low-frequency tasks, enabling frequency-adaptive operation without requiring all semiconductors to be oversized for the highest frequency stress
Solution Approach 2:
The system enables dynamic parameter changes by allowing different switching frequencies in the two converter circuits. The control unit can adjust the operating parameters of each converter independently, optimizing semiconductor stress distribution and allowing smaller semiconductor dimensions while maintaining adaptability to various frequency requirements
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 enhances efficiency, reduces filter requirements, and allows for a compact, cost-effective design with improved voltage quality and frequency-independent output impedance, suitable for various applications including three-phase machines and grid integration.
Implementation Method 1
The circuit arrangement (105) comprises a coupling unit (145) with a first three-phase connection (150) and a second three-phase connection (155); wherein the first three-phase converter circuit (115) and the second three-phase converter circuit (130) are electrically coupled to each other via the coupling unit (145)
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Device (100A) comprising a circuit arrangement (105) with a three-phase connection (110), wherein the circuit arrangement (105) comprises: a first three-phase converter circuit (115) comprising a three-phase connection (120) and a communication interface (125); a second three-phase converter circuit (130) comprising a three-phase connection (135) and a communication interface (140); a coupling unit (145) comprising a first three-phase connection (150) and a second three-phase connection (155); and a control unit (160) with a communication interface (165); characterized in that the first converter circuit (115) and the second converter circuit (130) are electrically coupled to each other via the coupling unit (145) such that the connection (120) is electrically coupled to the first connection (150);and the second terminal (155) is electrically coupled to the terminal (135) of the converter circuit; and wherein the second terminal (155) and the terminal (135) of the converter circuit are electrically coupled to the terminal (110) of the circuit arrangement; and wherein the three communication interfaces (125, 140, 165) are coupled together.;