Automotive variable voltage converter with multiple sets of power switches
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Solution Overview
Problem
Existing variable voltage converters (VVCs) face limitations in voltage gain, efficiency, and inductor size and current requirements, particularly when transitioning between low and high voltage sources, necessitating a high voltage gain with low inductor current to meet stringent power and voltage demands.
Innovation Solution
A novel VVC design incorporating series-connected switches, an inductor, and capacitors with complementary duty cycles, utilizing silicon and silicon carbide transistors to achieve high voltage gain with reduced inductor size and lower current stresses, enabling efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional variable voltage converters are used to increase voltage gain, then the voltage conversion capability is improved, but the inductor size and current requirements increase
Solution Approach 1:
The converter is divided into two independent voltage conversion paths: a first path with a first inductor and first switches for initial voltage conversion, and a second path with a second inductor and second switches for further voltage conversion. This segmentation allows each inductor to handle only a portion of the total voltage gain, reducing individual inductor size and current requirements while achieving high overall voltage gain through cascaded operation.
2Force
If conventional variable voltage converters are used to increase voltage gain, then the voltage conversion capability is improved, but the current through the inductor increases
Solution Approach 1:
The converter is divided into two independent voltage conversion paths: a first path with a first inductor and first switches for initial voltage conversion, and a second path with a second inductor and second switches for further voltage conversion. This segmentation allows each inductor to handle only a portion of the total voltage gain, reducing individual inductor size and current requirements while achieving high overall voltage gain through cascaded operation.
3Force
If series connected switches are used in the variable voltage converter, then the voltage output capability is improved, but the device complexity increases
Solution Approach 1:
The converter is divided into two independent voltage conversion paths: a first path with a first inductor and first switches for initial voltage conversion, and a second path with a second inductor and second switches for further voltage conversion. This segmentation allows each inductor to handle only a portion of the total voltage gain, reducing individual inductor size and current requirements while achieving high overall voltage gain through cascaded operation.
Solution Approach 2:
The controller operates the first and second pairs of switches with complementary duty cycles in a periodic manner, where the first pair switches during one phase and the second pair switches during another phase. This periodic operation simplifies control logic and reduces switching losses while maintaining continuous power transfer and achieving the desired voltage conversion ratio.
Data Source
AI summary
A variable voltage converter includes a pair of series connected switches, a series connected switch and inductor, and a capacitor having a terminal sharing a node with adjacent terminals of the series connected switches and another terminal sharing a node with adjacent terminals of the series connected switch and inductor such that during operation, a voltage input to the variable voltage converter and a voltage across the capacitor are same and less than a voltage output by the variable voltage converter.