Dynamic Current Limit for Wireless Power Communication

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Solution Overview

Problem

Wireless power systems using inductive coupling face issues with load pulses from devices like cell phones corrupting communication signals, leading to system voltage crashes and communication failures during power-up or charging, especially due to GSM pulses.

Innovation Solution

Implementing a dynamic current limit system that includes a current sense module, control module, and current limit module to detect and manage load pulses, enabling current limiting only when GSM pulses are detected, thereby preventing corruption of communication signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If inductive coupling is used to transfer power and transmit information concurrently, then power transfer efficiency is improved, but communication reliability deteriorates due to power transfer corrupting the transmission of information

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidcommunication reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements dynamic current limiting that adjusts the current limit based on detected communication activity. The system transitions from a static current limit to a dynamic one that is lowered specifically during communication packets, allowing high current for power transfer during non-communication periods while protecting communication integrity when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback from communication activity detection to control the current limiting behavior. The receiver detects communication packets and sends feedback to the transmitter, which then adjusts the current limit accordingly. This closed-loop feedback mechanism allows the system to automatically coordinate power transfer and communication without external intervention.

Inventive Principle:

Principle #23Feedback

2Reliability

If current limiting is applied continuously to prevent communication corruption, then communication reliability is improved, but power transfer efficiency deteriorates due to unnecessary current limitation during non-communication periods

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidpower transfer efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic current limiting that activates only during communication packet transmission intervals. Instead of continuous current limiting, the system applies current limits periodically synchronized with the communication protocol, allowing full power transfer during non-communication periods while protecting communication during designated communication windows.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the current limit based on the communication schedule, transitioning between high-current power transfer mode and low-current communication protection mode. This dynamic adjustment ensures current limiting is applied only when communication is active, eliminating unnecessary limitations during power transfer periods.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the current limit is lowered during communication packets, then communication reliability is improved, but the system becomes more complex requiring detection and control mechanisms

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the existing current limiting circuitry multi-functional by enabling it to operate in two modes: normal power transfer mode and communication protection mode. The same current limit module that protects against overcurrent during power transfer is also used to protect communication integrity, eliminating the need for separate protection circuits and reducing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses its own communication detection capability to trigger the current limiting action. The receiver's communication detection circuitry automatically informs the transmitter when communication is active, and the transmitter self-adjusts its current limit accordingly. This self-service mechanism eliminates the need for external control systems.

Inventive Principle:

Principle #25Self-service

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 dynamic current limit system effectively filters out GSM pulses, preventing voltage crashes and ensuring reliable communication by limiting current only when necessary, thus maintaining system stability and communication integrity.

Implementation Method 1

a current sense module configured to sense input current

Methodology Applied

Scientific EffectElectromagnetic sensing: Electromagnetic Induction

Implementation Method 2

Inductive coupling, often called magnetic coupling, couples magnetic energy from one coil to another coil

Methodology Applied

Scientific EffectInductive coupling: Electromagnetic Induction

Data Source

PatentUS8860370B2Systems and methods of dynamic current limit

Publication Date: 2014.10.14 TEXAS INSTRUMENTS INC

AI summary

Systems and methods of dynamic current limit are disclosed herein. A current is sensed a wireless charging circuit, for example. When the current sense reaches a reference current level while a communication is active, the current limit is enabled for the next packet. The current limit signal may be cleared for the next packet.