Capacitive Buck Converter for High Current Battery Charging

Solution Overview

Problem

Traditional battery charging architectures face inefficiencies at high charge currents due to power losses and heat generation, particularly in small devices like mobile phones, where inductive buck converters struggle with size constraints and efficiency, leading to significant conduction losses.

Innovation Solution

A capacitive buck converter design is implemented, shifting power losses to an external adapter, utilizing external floating capacitors to achieve high efficiency (>97%) at currents up to 8 amperes, and using USB 3.1 Type C or other fast charger adapters to provide adjustable voltage or current, minimizing conduction losses throughout the system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If inductive buck converters are used for battery charging, then voltage conversion can be achieved, but power losses and heat generation increase significantly at high charge currents

Engineering Contradiction:

Improvepower lossesVSAvoidcharging speed

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent replaces the inductive buck converter (which uses magnetic fields and inductors) with a capacitive buck converter that uses capacitive coupling and switching. This substitution eliminates the need for large inductors, reduces conduction losses, and enables efficient high-current charging by using capacitors to transfer energy through voltage switching rather than magnetic induction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental operating parameters by using high-voltage low-current transmission through the USB cable, then rapidly switching capacitor voltages to deliver high current to the battery. This parameter transformation (high voltage/low current in cable → low voltage/high current at battery) reduces I²R losses in the cable while maintaining fast charging capability.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If inductive buck converters are used for battery charging, then voltage conversion can be achieved, but device size increases due to inductor constraints

Engineering Contradiction:

Improvedevice sizeVSAvoidcharging speed

Core Design Contradiction:

Volume of moving objectVSProductivity

Solution Approach 1:

The patent replaces the inductive buck converter (which uses magnetic fields and inductors) with a capacitive buck converter that uses capacitive coupling and switching. This substitution eliminates the need for large inductors, reduces conduction losses, and enables efficient high-current charging by using capacitors to transfer energy through voltage switching rather than magnetic induction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If high charge currents are used for fast charging, then charging speed increases, but conduction losses increase significantly

Engineering Contradiction:

Improvecharging speedVSAvoidconduction losses

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent changes the fundamental operating parameters by using high-voltage low-current transmission through the USB cable, then rapidly switching capacitor voltages to deliver high current to the battery. This parameter transformation (high voltage/low current in cable → low voltage/high current at battery) reduces I²R losses in the cable while maintaining fast charging capability.

Inventive Principle:

Principle #35Parameter changes

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 capacitive buck converter design enables fast battery charging with minimized conduction losses, achieving efficiency near 100% and reducing heat generation, allowing for charging at high currents while maintaining a compact form factor.

Implementation Method 1

utilizing external floating capacitors to achieve high efficiency (>97%) at currents up to 8 amperes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

an adapter for receiving an alternating current (AC) signal and generating an adapter output

Methodology Applied

Scientific EffectElectrical energy conversion:

Implementation Method 3

a charger for generating a direct current (DC) signal based on the adapter signal

Methodology Applied

Scientific EffectElectrical energy conversion:

Data Source

PatentUS11101674B2Battery charging architectures

Publication Date: 2021.08.24 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A system may include an adapter, a charger, and a connector. The adapter is configured to receive an alternating current (AC) signal and generate an adapter signal, the adapter signal being generated based on an up-conversion of the AC signal. The charger is configured to generate a direct current (DC) signal from the adapter signal using one or more energy storage elements and supply the DC signal to a load, in which the adapter signal has a voltage greater than that of the DC signal. The connector is configured to couple the adapter and the charger. In some aspects, the adapter signal is adjusted based on one or more measurements of the DC signal at an output of the charger to maintain a target power for charging the load.