Capacitive Power Conversion Circuit Using Segmented Switching
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Solution Overview
Problem
Existing wireless power transmission systems using electric-field coupling face challenges in achieving a high voltage conversion ratio and efficiency while maintaining a compact size, as they require high-voltage elements and are inefficient due to the use of transformers and DC-DC converters.
Innovation Solution
A power conversion circuit with multiple three-terminal switching circuits, inductive impedance elements, and a switching control unit that alternately turns on and off high-side and low-side switching elements, reducing the need for high-voltage components and using low-on-resistance MOSFETs to minimize losses and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a transformer is used for voltage conversion, then voltage conversion is achieved, but the device size increases and manufacturing complexity increases
Solution Approach 1:
The patent replaces the mechanical transformer system with an electronic switching circuit system. Multiple three-terminal switching circuits with capacitors and switching elements (MOSFETs) perform voltage conversion through electronic switching and capacitive energy storage, eliminating the need for a physical transformer and its associated magnetic core and windings.
Solution Approach 2:
The voltage conversion function is divided into multiple independent three-terminal switching circuits. Each circuit handles a portion of the voltage conversion task through capacitive energy storage and switching, collectively achieving the overall voltage conversion ratio without requiring a single large transformer.
2Power
If a DC-DC converter is used for voltage conversion, then voltage conversion is achieved, but the conversion ratio is limited and device size increases
Solution Approach 1:
The DC-DC conversion function is segmented into multiple identical three-terminal switching circuits connected in series. Each circuit contributes a fixed voltage multiplication factor (e.g., 2x), and by cascading n circuits, the overall conversion ratio becomes 2^n, enabling high conversion ratios without increasing individual circuit complexity.
Solution Approach 2:
Each three-terminal switching circuit is designed as a universal module that can be replicated and cascaded. The same circuit topology, components, and control logic are used in each stage, allowing the system to achieve high voltage conversion ratios through simple replication rather than designing complex single-stage converters.
3Power
If high-voltage elements are used, then high voltage handling is achieved, but cost increases and device size increases
Solution Approach 1:
The high voltage handling capability is achieved by segmenting the voltage stress across multiple switching circuits. Each circuit only handles a fraction of the total voltage (e.g., V_in/2 per stage), allowing the use of low-voltage, low-cost switching elements and capacitors throughout the system rather than expensive high-voltage components.
Solution Approach 2:
Multiple low-voltage switching circuits are merged in series to collectively handle high voltage. The individual low-voltage circuits combine their voltage handling capabilities through series connection, achieving the equivalent of a high-voltage system using only low-voltage components.
4Power
If magnetic-field coupling is used for wireless power transmission, then power transmission is achieved, but position accuracy requirements increase and device size increases
Solution Approach 1:
The patent replaces magnetic-field coupling with electric-field coupling for wireless power transmission. This substitution changes the fundamental transmission mechanism from magnetic induction to electrostatic energy transfer, enabling relaxed position accuracy requirements and reduced device size through the use of planar electrode structures instead of bulky magnetic cores and coils.
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 solution achieves a high voltage conversion ratio and efficiency, reduces the size of the power conversion circuit, and lowers costs by avoiding the use of high-voltage elements and minimizing switching losses, while also synchronizing operations to reduce output voltage ripples.
Implementation Method 1
an input-side capacitor Cij connected between the first input portion and the second input portion
Implementation Method 2
an inductive impedance element L connected between output portions of the three-terminal switching circuits and a load
Data Source
AI summary
A power conversion circuit includes multiple input-side capacitors connected in series between input terminals; series circuits composed of high-side switching elements and low-side switching elements connected in parallel to the multiple input-side capacitors; and output-side capacitors connected between nodes and a node. The circuit further includes an output-side inductor connected to the node and a controller that alternately turns on and off the high-side switching elements and the low-side switching elements. Each of the low-side switching elements and the high-side switching elements is a MOSFET and causes current to flow from the low side to the high side using a body diode. Accordingly, there is provided a power conversion circuit that has high conversion efficiency and that is capable of realizing reduction in size, a power transmission system, and a power conversion system.