SiC Transistor Power Conversion for Rooftop Solar Weight Reduction
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Solution Overview
Problem
There is a need for more efficient and cost-effective power conversion systems, particularly DC-to-DC converters and DC-to-AC inverters for solar power systems, that also consider the weight constraint for rooftop installations.
Innovation Solution
A power conversion apparatus using silicon carbide transistors for hard-switching in both boost converters and inverters, achieving high power-to-weight ratios by packaging these components in a sealed, weatherproof housing, and utilizing a boost converter to boost DC output from solar panels to a desired voltage before converting it to a sinusoidal AC signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional silicon-based power conversion systems are used, then reliability is maintained, but weight is excessive for rooftop installations
Solution Approach 1:
The patent changes the material parameter from conventional silicon-based transistors to silicon carbide (SiC) transistors. This material substitution enables the system to operate at higher switching frequencies (70-100 kHz for DC-DC conversion, 35-60 kHz for AC-DC conversion) while maintaining reliability, ultimately achieving weight reduction through smaller component sizes.
Solution Approach 2:
The patent implements dynamic hard-switching operation of silicon carbide transistors in both the boost converter and inverter stages. This dynamic switching approach allows the system to achieve higher power density and efficiency (exceeding 99% conversion efficiency) while reducing the size and weight of magnetic components and overall system architecture.
2Power
If switching frequency is increased to reduce component size, then power density improves, but switching losses increase
Solution Approach 1:
The patent changes the semiconductor material parameter to silicon carbide, which has superior switching characteristics compared to conventional silicon. This material change enables hard-switching operation at high frequencies (70-100 kHz for DC-DC, 35-60 kHz for AC-DC) with minimal switching losses, achieving power density exceeding 1 kW/kg while maintaining efficiency over 99%.
3Power
If silicon carbide transistors are used for hard switching, then power-to-weight ratio exceeds 1 kW/kg, but manufacturing complexity increases
Solution Approach 1:
The patent merges the DC-DC conversion stage (boost converter) and AC-DC inversion stage into a single integrated power conversion apparatus. Both stages utilize silicon carbide transistors operating in hard-switching mode, achieving power-to-weight ratio exceeding 1 kW/kg and efficiency over 99% while being packaged together in a sealed, weatherproof housing suitable for rooftop solar installations.
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AI summary
A power conversion apparatus and individual components thereof is described. In general, the power conversion apparatus converts a DC output received from an appropriate source, such as string of solar panels, to an AC output. The AC output may be a single-phase or three-phase, sinusoidal AC signal. The inverter system may include a boost converter, which is a DC-to-DC converter, and an inverter, which is essentially a DC-AC converter. In operation, the boost converter will boost the DC output from the appropriate source to a desired DC output voltage. The inverter will convert the DC output voltage to a desired single-phase or three-phase output voltage at a desired frequency, such as 50 or 60 hertz. The boost converter and the inverter may be packaged together in an appropriate sealed and weatherproof housing.