Isolated Differential Voltage Probe for EMI Noise Source Identification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing differential voltage probes fail to provide accurate measurements at high frequencies, galvanic isolation, and sufficient common-mode rejection ratio, limiting their effectiveness in identifying noise sources in EMI/EMC applications, particularly in power electronics devices.
Innovation Solution
A unique isolated differential voltage probe design featuring a transformer with specific winding configurations and capacitors, providing galvanic isolation and optimized common-mode rejection ratio, enabling accurate differential voltage measurements up to 300 MHz and maintaining high CMRR across the frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing differential voltage probe designs are used, then device complexity is reduced, but measurement precision deteriorates at high frequencies
Solution Approach 1:
The probe divides the measurement function into separate components: a first probe tip for first signal input, a second probe tip for second signal input, and a transformer with primary and secondary windings for signal transformation and isolation. This segmentation allows each component to be optimized for its specific function, achieving high-frequency measurement precision while maintaining manageable complexity.
Solution Approach 2:
The transformer acts as an intermediary element between the probe tips and the measurement device. It provides galvanic isolation and transforms the differential voltage signal, enabling accurate high-frequency measurements without directly coupling the measurement device to the high-frequency signal source, thus improving measurement precision.
2Object-affected harmful factors
If existing probe designs are used, then ease of manufacture is improved, but common-mode rejection ratio deteriorates at high frequencies
Solution Approach 1:
The transformer serves as an intermediary that inherently provides common-mode rejection through its magnetic coupling mechanism. The magnetic core and winding configuration reject common-mode signals while passing differential signals, achieving high CMRR at high frequencies without adding complex active rejection circuits that would increase manufacturing difficulty.
Solution Approach 2:
The design replaces electronic common-mode rejection circuits with a magnetic field-based transformer mechanism. The transformer's magnetic coupling naturally rejects common-mode signals through electromagnetic induction, providing passive CMRR that is effective at high frequencies without requiring complex electronic control or additional active components.
3Reliability
If existing probe designs are used, then device complexity is reduced, but galvanic isolation is lost
Solution Approach 1:
The transformer acts as a galvanic isolation intermediary, magnetically coupling the primary winding (connected to probe tips) with the secondary winding (connected to measurement device). This magnetic coupling transfers energy and signal information without direct electrical connection, providing galvanic isolation that improves reliability while adding only one component.
Solution Approach 2:
The transformer performs multiple functions simultaneously: it provides galvanic isolation, transforms differential voltage signals, and rejects common-mode signals. This multi-functionality achieves reliable isolation without requiring separate components for each function, thereby limiting the increase in device complexity.
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 probe achieves accurate differential voltage measurements and high CMRR, allowing for efficient identification of noise sources in power electronics, with flexible design accommodating various frequency and voltage requirements, and easy implementation at a low cost.
Implementation Method 1
a transformer comprising a magnetic core, a primary winding, and a first secondary winding
Implementation Method 2
a first capacitor coupled to the primary winding, and a second capacitor coupled to the primary winding
Data Source
AI summary
A differential voltage probe for providing accurate measurement of differential voltage with high frequency components is disclosed that is further configured to accurately identify noise sources in EMI/EMC applications. The differential voltage probe is configured to provide the benefits of adequate differential voltage measurement bandwidth, galvanic isolation capability, high CMRR, flexible design to accommodate various requirements on voltage rating, loading effect, and frequency range of interest; and/or easy implementation and low cost. The differential voltage probe is able to achieve these optimized capabilities by implementing unique winding designs for transformer(s) used in the differential voltage probe circuit design.