Series-Parallel Switched Capacitor Converter With Zero-Voltage Switching
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Solution Overview
Problem
Current series-parallel switched capacitor voltage converters suffer from low conversion efficiency and high switching loss due to significant voltage differences across switch transistors during switching.
Innovation Solution
The addition of an inductor and switch transistors between the branches of a conventional series-parallel switched capacitor voltage converter allows for the transfer of electric charges on parasitic capacitors from one branch to another during a short dead time, effectively reducing the voltage difference across primary switch transistors to zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional series-parallel switched capacitor voltage converter structure is used, then the device can convert input DC voltage to output DC voltage, but the switching loss is large and conversion efficiency is low due to significant voltage differences across switch transistors during switching
Solution Approach 1:
The inductor is used to pre-charge or discharge parasitic capacitors during the dead time before the main switch transistors are turned on, ensuring that the voltage difference across the switch transistors is reduced to zero before switching occurs. This preliminary action of charge transfer eliminates the voltage difference that would otherwise cause significant switching losses.
Solution Approach 2:
The inductor acts as an intermediary component between the two branches of the switched capacitor converter. It facilitates the transfer of electric charges during the dead time, mediating the voltage balance between branches and enabling zero-voltage switching conditions for the main transistors, thereby reducing switching losses.
2Reliability
If an inductor and switch transistors are added to transfer charges during dead time, then switching loss is reduced and conversion efficiency is improved, but device complexity increases
Solution Approach 1:
The inductor serves multiple functions: it acts as an energy storage element, a charge transfer medium between branches, and a means to achieve zero-voltage switching. By making this single component multi-functional, the patent reduces the need for additional complex circuitry while still achieving the goal of improved conversion efficiency.
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 significantly reduces switching loss and improves conversion efficiency by ensuring zero voltage switching for the primary switch transistors.
Implementation Method 1
The addition of an inductor and switch transistors between the branches of a conventional series-parallel switched capacitor voltage converter allows for the transfer of electric charges on parasitic capacitors from one branch to another during a short dead time
Data Source
AI summary
A series-parallel switched capacitor voltage converter includes inductive branch, a first branch and a second branch, the inductive branch is connected between the first branch and the second branch. By controlling turning on and off of the switches of the first branch, the second branch and inductive branch, charges on capacitors of one branch are completely transferred to another branch via the inductive branch within a period of time after all main switches of the first branch and the second branch are turned off, and a voltage difference between both terminals of each of the main switches becomes zero, then each of the main switches is started to be turned on, the voltage difference of each of the main switches is zero at an instant when the main switches are turned on.