Switched-Capacitor Gate Driver Supply With Cascoded MOSFET Switching
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Solution Overview
Problem
Switched-capacitor power converters face inefficiencies due to high voltage drops across transistors and the need for multiple types of devices, increasing fabrication costs and complexity, particularly in integrating low-voltage and high-voltage transistors for efficient gate driving.
Innovation Solution
The implementation of a controller-driven apparatus with gate drivers powered by capacitors, using cascoded transistor switches and resistor dividers to maintain efficient gate-to-source voltages, allowing for the use of low-voltage transistors and reducing the number of high-voltage devices, and employing dual-phase converters to distribute charge transfer paths for enhanced efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high-voltage transistors are used to handle high voltage in switched-capacitor converters, then voltage handling capability is improved, but transistor efficiency deteriorates due to high voltage drops
Solution Approach 1:
The patent divides the voltage handling function into two separate components: low-voltage transistors for efficient switching and high-voltage capacitors for voltage multiplication. This segmentation allows each component to operate in its optimal voltage range, with low-voltage transistors avoiding high voltage drops while high-voltage capacitors handle the voltage multiplication function.
Solution Approach 2:
The patent combines low-voltage transistor switching with high-voltage capacitor networks to achieve high-voltage conversion. The low-voltage transistors control charge transfer to high-voltage capacitors, which then multiply the voltage through their series/parallel reconfiguration. This merging allows efficient low-voltage switching to drive high-voltage output without subjecting transistors to high voltage stress.
2Adaptability or versatility
If multiple types of devices (low-voltage and high-voltage transistors) are integrated, then voltage range capability is improved, but device complexity and fabrication cost increase
Solution Approach 1:
The patent makes low-voltage transistors perform multiple functions: they switch charge to both low-voltage and high-voltage capacitors, and control the timing of voltage multiplication. This multi-functionality eliminates the need for separate high-voltage transistors, reducing device types while maintaining full voltage range capability through the capacitor network.
Solution Approach 2:
The patent introduces high-voltage capacitors as intermediary energy storage elements between low-voltage transistors and high-voltage output. These capacitors mediate the voltage transformation, allowing low-voltage transistors to indirectly control high-voltage switching without direct exposure to high voltage, thereby simplifying the transistor requirements.
3Stress or pressure
If high-voltage transistors are used, then high voltage switching capability is improved, but fabrication cost increases
Solution Approach 1:
The patent uses inexpensive low-voltage transistors that can be manufactured with standard processes, replacing costly high-voltage transistors. The low-voltage transistors are paired with high-voltage capacitors that handle the voltage stress, allowing the use of cheaper, more readily available transistor technologies while achieving the same high-voltage switching capability.
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 approach enhances the efficiency of switched-capacitor power converters by minimizing charge deposition and discharge on transistors, enabling the use of low-voltage transistors and reducing fabrication costs, while maintaining efficient gate driving and voltage management.
Implementation Method 1
a first capacitor set and a second capacitor set. The first set comprises a capacitor having an anode thereof connected to a first phase voltage and the second set comprises a capacitor having an anode thereof connected to a second phase voltage
Implementation Method 2
driving a switch requires causing charge to flow into a gate terminal so as to cause an electric field. In an enhancement mode MOSFET, this electric field causes an inversion layer that permits charge to flow between source and drain
Data Source
AI summary
An apparatus includes first and second pluralities of switches, a controller for controlling these switches, gate-drivers for driving switches from the first plurality of switches, and first and second terminals configured for coupling to corresponding first and second external circuits at corresponding first and second voltages. During operation, the controller causes the first plurality of switches to transition between states. These transitions result in the second voltage being maintained at a value that is a multiple of the first voltage. The controller also causes the second plurality of switches to transition between states. These transitions resulting in capacitors being coupled or decoupled from the second voltage. The gate drivers derive, from the capacitors, charge for causing a voltage that enables switches from the first plurality of switches to be driven.