PCB Shield Resistor Crosstalk EMI Power Meter
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Solution Overview
Problem
Existing power meters suffer from inaccuracies due to electromagnetic interference (EMI) and crosstalk from high-power components and adjacent phase inputs, leading to signal degradation and increased percent error in measurements.
Innovation Solution
The implementation of shielded printed circuit boards (PCBs) with conductive materials placed between resistors and power supply components to block electromagnetic fields, combined with resistor orientation and optional flexible PCB shields to minimize parasitic capacitance and protect against EMI and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shielded PCBs are added to block electromagnetic fields, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent embeds conductive shielding layers directly within the PCB structure itself, nesting the shielding function inside the existing circuit board. The conductive material is integrated into the PCB layers, creating a nested configuration where the shield is contained within the PCB rather than being a separate external component.
Solution Approach 2:
The PCB serves multiple functions simultaneously: it provides electrical connectivity for the circuit, structural support for mounting components, and electromagnetic shielding through its integrated conductive layers. This multi-functionality eliminates the need for separate shielding components, reducing overall device complexity while maintaining measurement precision.
2Productivity
If resistors are placed close to power supply components to reduce space, then productivity is improved, but measurement precision deteriorates due to EMI and crosstalk
Solution Approach 1:
The shielding conductors are nested within the PCB layers between the power supply components and the measurement resistors. This nested configuration allows close proximity placement while maintaining signal integrity by having the shielding layer physically interposed between the interference sources and sensitive circuits.
Solution Approach 2:
The conductive shielding layers act as intermediary elements between the power supply components and the measurement resistors. These intermediary shields provide a controlled impedance path that mediates the electromagnetic interaction, preventing direct coupling of EMI and crosstalk while allowing the components to remain in close proximity for space efficiency.
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
This configuration significantly reduces measurement variability from 0.05% to less than 0.005%, ensuring accuracy and compliance with stringent regulations by effectively shielding resistors from EMI and crosstalk interference.
Implementation Method 1
a shield composed of one or more shielded printed circuit boards (PCBs) having a conductive material inside the rigid or flexible printed circuit boards such that the shield exists in a path of the electromagnetic energy produced by the power supply
Implementation Method 2
A resistor sandwiched between two grounded PCB shields can look and behave like a capacitor, creating further unwanted effects on the input signals being measured by the power meter
Data Source
AI summary
A shield that protects high-value input resistors in a power meter against unwanted effects due to electromagnetic interference from a nearby power supply and/or due to crosstalk from adjacent phases. The shield includes multiple printed circuit board shields that are arranged between each of the input resistors on a main printed circuit board in the power meter. Each PCB shield has a conductive layer that provides the shielding against unwanted energy. The resistors are arranged in a diagonal or parallel manner between each pair of PCB shields to prevent the resistor from movement, which prevents pin fatigue and fixes the value of the parasitic capacitance that is produced in the resistor-PCB-shield combination. In another configuration, the PCB shield is made of a flexible material, and snakes between and over the top or around the side ends of each resistor in a serpentine fashion, protecting the resistors from unwanted energies from both the top and the sides. The PCB shields disclosed herein eliminate variations in the percent error of the measurement phases, which contributes to achieving a highly accurate meter with an overall accuracy of less than 0.1%.