SiC Medium Voltage Drive System for High Speed Machine Applications
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Solution Overview
Problem
Current medium voltage power converters, primarily based on silicon technology, are limited by high switching losses, which restrict their operation to fundamental frequencies below 120 Hz, resulting in inefficiencies and reduced power density, failing to meet demands for higher frequency operations and improved efficiencies above 95%.
Innovation Solution
The development of a medium voltage power converter using silicon carbide (SiC) devices and a hybrid topology with IGBT and SiC-based stages, coupled with advanced transformer designs and cooling systems, enables operation at frequencies up to 1000 Hz and efficiencies exceeding 97%, addressing the limitations of traditional silicon-based systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If silicon-based power converter technology is used, then system reliability is maintained, but switching losses increase and efficiency drops below 97% when operating above 120 Hz
Solution Approach 1:
The patent changes the material parameter from silicon to silicon carbide (SiC), which fundamentally alters the switching loss characteristics. SiC devices enable operation at frequencies up to 1000 Hz with efficiencies exceeding 97%, directly resolving the contradiction between maintaining reliability and reducing switching losses at high frequencies.
Solution Approach 2:
The patent employs a hybrid topology combining IGBT and SiC-based stages. This composite approach leverages the strengths of both technologies: IGBT for robustness and SiC for low loss and high frequency performance, achieving both reliability and efficiency above 97% at frequencies up to 1000 Hz.
2Power
If silicon-based converters operate at higher frequencies, then power density improves, but switching losses cause system de-rating and efficiency reductions
Solution Approach 1:
By changing the semiconductor material from silicon to silicon carbide, the patent enables high frequency operation (up to 1000 Hz) without the switching loss penalties that normally cause de-rating. This material parameter change allows simultaneous achievement of high power density and low switching losses.
Solution Approach 2:
The patent implements a dynamic hybrid topology that can operate in different modes (IGBT-based or SiC-based) depending on frequency requirements. This dynamic adaptability allows the system to optimize power density at high frequencies using SiC while maintaining stability through IGBT control at lower frequencies.
3Speed
If traditional multi-level medium voltage power converter technology is used, then system stability is maintained, but fundamental frequency operation is limited to 0-120 Hz
Solution Approach 1:
The patent changes the switching frequency parameter from the traditional 600 Hz limit to operation up to 1000 Hz by adopting SiC technology. This parameter change enables direct drive applications at higher speeds while SiC's inherent properties maintain system stability through reduced switching losses and improved thermal performance.
Solution Approach 2:
The patent creates a dynamic system that can adapt its operating frequency based on load requirements, enabling fundamental frequency operation from 50/60 Hz up to 1000 Hz. The hybrid IGBT-SiC topology provides dynamic control capabilities that maintain stability across this extended frequency range.
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 solution enables high-speed machine drive systems with bidirectional power transfer, achieving higher efficiencies and power density while supporting operation at frequencies beyond the capabilities of traditional silicon-based converters.
Implementation Method 1
Operation at higher fundamental frequencies is prohibited due to high switching loss causing stiff system de-rating, dramatic system efficiency and power density reductions
Implementation Method 2
a transformer including a plurality of primary windings to couple to a utility source of input power and a plurality of secondary windings
Data Source
AI summary
In one aspect, a medium voltage power converter includes a plurality of slices each having: a transformer including a plurality of primary windings to couple to a utility source of input power and a plurality of secondary windings; and a plurality of power cubes coupled to the plurality of secondary windings, each of the plurality of power cubes comprising a low frequency front end stage, a DC link, and a high frequency silicon carbide (SiC) inverter stage to couple to a high frequency load or to a high speed machine.