Adiabatic Switched-Capacitor AC-DC Conversion With Low Ripple
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Solution Overview
Problem
Existing power conversion technologies for charging portable devices from AC sources suffer from inefficiencies due to energy losses in the conversion process.
Innovation Solution
The implementation of an adiabatic switched capacitor circuit in a two-stage power-conversion system, where the first stage is a pre-regulating circuit and the second stage is a switched-capacitor converter, allows for efficient conversion between AC and DC voltages by utilizing bypass switches and an LC filter for adiabatic operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional power conversion circuits are used to transform AC to DC, then voltage conversion is achieved, but energy loss increases
Solution Approach 1:
The power conversion system is divided into two distinct stages: a pre-regulating circuit (first stage) and a switched-capacitor converter (second stage). This segmentation allows each stage to perform a specific function optimized for minimal energy loss, with the first stage handling initial rectification and regulation, and the second stage performing high-efficiency voltage conversion through capacitive switching rather than inductive transformation.
Solution Approach 2:
The patent replaces traditional magnetic inductive conversion mechanisms with a switched-capacitor based system. Instead of using transformers and inductors for voltage conversion, the invention uses capacitors switched by electronic switches (MOSFETs or similar), eliminating magnetic core losses, winding resistance losses, and associated electromagnetic interference, thereby significantly reducing energy loss in the conversion process.
2Loss of energy
If switched-capacitor converter is used in the second stage, then energy efficiency is improved, but circuit complexity increases
Solution Approach 1:
The switched-capacitor converter circuit is designed to perform multiple functions within a single integrated structure. The same capacitor network and switching elements that perform voltage conversion also provide voltage regulation, ripple filtering, and adaptive charging capabilities. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby managing overall circuit complexity despite the advanced conversion mechanism.
Solution Approach 2:
The circuit incorporates adaptive switching control where the switching frequency and duty cycle are dynamically adjusted based on load conditions and voltage requirements. The controller monitors the charging state and power delivery, modifying the switching parameters in real-time to optimize efficiency across varying operating conditions. This dynamic adaptation allows the complex switched-capacitor circuit to maintain high efficiency without requiring equally complex external control systems.
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 reduces energy losses and achieves high efficiency in power conversion, enabling the production of a DC voltage with minimal ripple and reduced size and power loss in the converter.
Implementation Method 1
the capacitor is adiabatically charged by passing a current through an inductor and is adiabatically discharged by passing the current through a load
Implementation Method 2
The first switched-capacitor stage includes a first inductor, a first capacitor, and a first switch arranged in a bridge circuit
Data Source
AI summary
An apparatus for conversion between AC and DC voltages includes a rectifier and first and second stages coupled to each other and having a regulator and a switched-capacitor circuit respectively. The first stage receives a first voltage from the rectifier and the second stage provides a second voltage. A controller controls the first and second stages.