Modular SiC Medium Voltage Converter With High Frequency Transformers
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Solution Overview
Problem
Current modular medium voltage drive systems lack suitable commercial applications due to limited options for modular transformers in solid state transformer topologies, particularly at high switching frequencies, and require bulky 60 Hz transformers for galvanic isolation.
Innovation Solution
A modular reduced-size multi-MW SiC-based medium voltage conversion system utilizing high frequency line converters and transformers with SiC stages, coupled with a two-phase cooling system, to achieve compact and efficient power conversion with reduced passive component size and increased power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If solid state transformer topology is used for reduced size medium voltage drive system, then power density is improved, but suitable commercial applications are limited due to lack of modular transformer options at high switching frequencies
Solution Approach 1:
The system is divided into modular power cells, each containing a high frequency line converter, high frequency transformer, and high frequency motor converter. This segmentation enables the transformers to be independently designed for high frequency operation, making them commercially available while achieving high power density in the overall drive system.
2Volume of moving object
If high frequency transformers are used in modular power cells, then transformer size is reduced, but cooling requirements become more complex due to high switching frequencies
Solution Approach 1:
The cooling system is integrated directly into the power cell module structure, with cooling channels combined with the transformer and converter housings. This merging of cooling functions into the existing modular structure reduces overall system complexity despite the high frequency operating conditions.
3Loss of energy
If SiC switching devices are used in high frequency converters, then switching losses are reduced, but manufacturing complexity increases due to wide bandgap technology requirements
Solution Approach 1:
The system operates at high switching frequencies (20-100 kHz) which, combined with SiC devices, reduces switching losses. The high frequency operation changes the operating parameters of the transformers and converters, allowing them to be designed in compact modular forms that are more manufacturable despite the advanced semiconductor technology used.
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 system achieves compact modularity, high power density, and reduced footprint by integrating high frequency transformers within power cells, eliminating the need for bulky 60 Hz transformers and providing galvanic isolation, while maintaining low harmonic distortion and efficient power transfer.
Implementation Method 1
a two-phase cooling system having conduits that are adapted to provide a flow of cooling media through the HFLC, the transformer and the HFMC
Implementation Method 2
a transformer having a primary coil coupled to the HFLC and a secondary coil coupled to a high frequency motor converter (HFMC)
Implementation Method 3
the HFLC including a first silicon carbide (SiC) stage and a second SiC stage; the HFMC including a third SiC stage and a fourth SiC stage
Data Source
AI summary
In one embodiment, a power cell module includes: a high frequency line converter (HFLC) to receive a phase of input power from a utility source, the HFLC including a first silicon carbide (SiC) stage and a second SiC stage; a transformer having a primary coil coupled to the HFLC and a secondary coil coupled to a high frequency motor converter (HFMC); the HFMC to output a phase of output power to a load, the HFMC including a third SiC stage and a fourth SiC stage; and a two-phase cooling system having conduits that are adapted to provide a flow of cooling media through the HFLC, the transformer and the HFMC.