Capacitive Power Transfer System for High CMTI Isolation

Solution Overview

Problem

Systems with low voltage and high voltage circuits face common mode transient immunity (CMTI) issues due to high voltage transients, which can cause data errors, and existing electrical isolation barriers do not always prevent these issues.

Innovation Solution

A power transfer system using differential signals with isolation elements like capacitors to transmit and rectify power between low voltage and high voltage circuits, including a digital rectifier and controller to monitor and adjust the rectified voltage, thereby enhancing CMTI and preventing data errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrical isolation barriers are used between high voltage and low voltage circuits, then common mode transient immunity is improved, but data errors still occur under transient conditions

Engineering Contradiction:

Improvecommon mode transient immunityVSAvoiddata errors

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent introduces capacitive coupling as an intermediary mechanism between high voltage and low voltage circuits. The capacitor transfers power signals while blocking transient voltage spikes and common mode noise, acting as a mediator that allows useful signal transmission while filtering out harmful transients that cause data errors.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the electrical parameters at the interface between high voltage and low voltage circuits by using capacitive coupling. This transforms the direct conductive connection into a reactive coupling, fundamentally changing how signals and transients are transmitted across the voltage boundary, thereby improving immunity while maintaining power transfer.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If isolation barriers are implemented to prevent high voltage transients, then circuit safety is improved, but power transfer efficiency deteriorates

Engineering Contradiction:

Improvecircuit safetyVSAvoidpower transfer efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the electrical parameters at the interface between high voltage and low voltage circuits by using capacitive coupling. This transforms the direct conductive connection into a reactive coupling, fundamentally changing how signals and transients are transmitted across the voltage boundary, thereby improving immunity while maintaining power transfer.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional electromagnetic isolation mechanisms with a simpler capacitive coupling approach. This substitution achieves isolation and transient protection without the complexity and losses associated with traditional transformers or isolation barriers, improving both safety and efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of energy

If direct connection between high voltage and low voltage circuits is used, then power transfer efficiency is maintained, but transient immunity deteriorates

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidtransient immunity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent introduces capacitive coupling as an intermediary mechanism between high voltage and low voltage circuits. The capacitor transfers power signals while blocking transient voltage spikes and common mode noise, acting as a mediator that allows useful signal transmission while filtering out harmful transients that cause data errors.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 system effectively transfers power across voltage boundaries without causing data errors, even under transient conditions, by using capacitors as isolation elements and a digital rectifier to generate and regulate voltages, improving common-mode transient immunity.

Implementation Method 1

a first isolation element, such as a capacitor, for transmitting a first component of the differential signal between the first and second circuits

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

A digital rectifier is coupled to the first and second isolation elements for generating a rectified voltage in response to the first and second components of the differential signal

Methodology Applied

Scientific EffectRectification: Diode

Data Source

PatentUS9456257B2Device for transferring power from a first circuit to a second circuit

Publication Date: 2016.09.27 TEXAS INSTRUMENTS INC

AI summary

A power transfer system for transferring power from a first circuit to a second circuit by a differential signal generated in the first circuit includes a first isolation element for transmitting a first component of the differential signal between the first and second circuits. The system also includes a second isolation element for transmitting a second component of the differential signal between the first and second circuits. A digital rectifier is coupled to the first and second isolation elements for generating a rectified voltage in response to the first and second components of the differential signal. The system includes circuitry for monitoring the rectified voltage and generating a signal representative of the rectified voltage. The system also includes a controller for changing the rectified voltage in response to the signal representative of the rectified voltage.