Wearable Wireless Charging Circuit With Dual Charging Paths

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Solution Overview

Problem

Existing wireless charging technologies for wearable devices face inefficiencies in power transfer and charging modes, leading to suboptimal charging performance due to variations in input voltage and battery state, without effectively adapting to different usage states like sleep or active modes.

Innovation Solution

A wireless charging circuit for wearable devices that includes a wireless receiver, a charge pump circuit, and a step-down converter circuit, controlled by a controller to select the appropriate charging path based on voltage differences and battery state, utilizing electromagnetic induction for power transfer and adjusting coil voltage to optimize charging efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single charging path is used for wireless charging, then the circuit structure is simple, but the charging efficiency is suboptimal due to inability to adapt to different input voltages and battery states

Engineering Contradiction:
Improvecharging efficiencyVSAvoidcircuit structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The charging circuit is segmented into multiple independent charging paths: a first charging path using a charge pump circuit for voltage multiplication, and a second charging path using a step-down converter circuit for voltage regulation. The controller selectively activates one path based on the voltage difference between input voltage and battery voltage, enabling efficient charging across different voltage conditions without requiring a single complex adaptive circuit.

Inventive Principle:
Principle #1Segmentation

2Loss of energy

If the input voltage is much higher than the battery charging voltage, then power transfer can be initiated, but power loss increases and charging efficiency decreases

Engineering Contradiction:
Improvepower lossVSAvoidcharging efficiency
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The system changes the voltage transformation parameter dynamically by selecting different charging paths. When the voltage difference exceeds a threshold (indicating high power loss risk), the controller activates the charge pump circuit to multiply the input voltage in stages, reducing the voltage differential and associated power losses. When the voltage difference is within acceptable range, the step-down converter circuit is used for direct efficient regulation, optimizing charging efficiency under varying voltage conditions.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If wireless charging is implemented in wearable devices, then beauty and comfort are improved, but charging performance becomes suboptimal due to space constraints and power limitations

Engineering Contradiction:
Improvebeauty and comfortVSAvoidcharging performance
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The charging system implements dynamic adaptation by continuously monitoring the voltage difference between the wireless charging input and battery charging voltage, then dynamically selecting the appropriate charging path. The controller adjusts the charging configuration in real-time based on operating conditions, enabling the system to maintain optimal charging performance despite the power and space constraints inherent in wearable device wireless charging implementations.

Inventive Principle:
Principle #15Dynamics

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 reduces power loss and improves charging efficiency by dynamically selecting the charging path and adjusting coil voltage, ensuring efficient charging across varying input voltages and usage states, thereby enhancing the overall charging experience for wearable devices.

Implementation Method 1

a wireless receiver, configured to receive a charging power transmitted by a wireless transmitter of a wireless charging apparatus through electromagnetic induction

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4312337A1Circuit of wireless charging, method of charging battery and wearable device
Publication Date: 2024.01.31 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4312337A1 patent drawingFigure 1
  • EP4312337A1 patent drawingFigure 2
  • EP4312337A1 patent drawingFigure 3

AI summary

A circuit of wireless charging, a method of charging a battery, and a wearable device. The circuit includes: a wireless receiver (10); a charge pump circuit (12) connected to a voltage output end of the wireless receiver (10), configured to receive an input voltage from the voltage output end that is boosted, and step down the input voltage to an output voltage of the charge pump circuit (12) to charge a battery; a step-down converter circuit (13) configured to perform the step-down charging on the battery in response to determining that a charging mode is in a constant voltage mode; a controller (14) configured to select one between the charge pump circuit (12) and the step-down converter circuit (13) as a charging path to charge the battery based on a voltage difference between the input voltage from the voltage output end of the wireless receiver (10) and a charging voltage of the battery.