Adaptive Common Mode Dimmer for BCI Suppression

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Solution Overview

Problem

Existing common-mode dimmer circuits consume significant power due to high quiescent current operation, even when no bulk current injection (BCI) events occur, as they need to maintain sufficient drive/sink current capacity to handle BCI events.

Innovation Solution

An adaptive common-mode dimmer circuit with low and high operating quiescent current modes, switching between modes based on common-mode voltage levels, operates at minimal power during normal conditions and increases current capacity during BCI events, using voltage comparators and transistors to adjust current sourcing/sinking accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the common mode dimmer operates at high quiescent current to guarantee sufficient drive/sink current capacity, then the ability to handle BCI events is improved, but the power consumption during normal operation increases significantly

Engineering Contradiction:

Improveability to handle BCI eventsVSAvoidpower consumption during normal operation

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic operation of the common mode dimmer by switching between two distinct operating modes: a low-power mode for normal operation and a high-current mode for BCI event suppression. The circuit uses voltage comparators to detect common mode voltage levels and automatically transitions between modes, allowing the drive/sink current capacity to be dynamically adjusted based on actual conditions rather than maintaining constant high current capability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameters of the common mode dimmer based on detected conditions. When a BCI event is detected (common mode voltage exceeds thresholds), the circuit changes from low quiescent current operation to high current operation, effectively changing the electrical parameters to match the required performance level only when needed

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the common mode dimmer maintains high drive/sink current capacity at all times, then the suppression of common mode radiation is improved, but the system power drain increases

Engineering Contradiction:

Improvecommon mode radiation suppressionVSAvoidsystem power drain

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent employs periodic monitoring of the common mode voltage level through voltage comparators that continuously check whether the voltage exceeds predefined thresholds. This periodic detection enables the circuit to activate high-current operation only during BCI events rather than maintaining constant high current, reducing energy loss while ensuring radiation suppression capability when needed

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent implements a feedback mechanism where the common mode voltage level is continuously monitored and fed back to the control logic. When the voltage exceeds thresholds indicating a BCI event, the feedback triggers the circuit to switch to high-current mode for effective suppression. This closed-loop feedback ensures energy is consumed only when suppression is actually required

Inventive Principle:

Principle #23Feedback

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 adaptive common-mode dimmer reduces power consumption during normal operation while maintaining high current capacity during BCI events, effectively suppressing common-mode radiation with minimal power drain.

Implementation Method 1

the first and second voltage comparators having outputs coupled to and controlling the first and second sets of current drivers, respectively, first inputs coupled to the two-wire transmission line, and second inputs coupled to a first reference voltage

Methodology Applied

Scientific EffectVoltage comparison:

Implementation Method 2

When Vcm is greater than Vmid, the second set of current drivers will sink more current than the first set of current drivers will source. When Vcm is less than Vmid, the first set of current drivers will source more current than the second set of current drivers will sink

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS10120406B1Adaptive common mode dimmer

Publication Date: 2018.11.06 MICROCHIP TECHNOLOGY INC

AI summary

An adaptive mode has been added in a common mode (CM) dimmer circuit to increase output current capability only when needed. Without having an adaptive mode in the CM dimmer, the output current drivers must operate with large quiescent current to handle a bulk current injection (BCI) event. Therefore, a CM dimmer without the adaptive mode will consume a significant amount of power even when there is no BCI event occurring. With the adaptive mode, the CM dimmer can be used effectively to suppress the BCI event, e.g., in a transformer-less physical layer (PHY) connection, while consuming minimal power during normal circuit operation.