Common Mode Voltage Measurement Using Parasitic Capacitance Compensation
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Solution Overview
Problem
Existing common-mode voltage measurement apparatuses require complex configurations and special-shaped capacitive voltage probes, making them bulky and costly, while also being affected by parasitic capacitive components that reduce measurement accuracy.
Innovation Solution
A common-mode voltage measurement apparatus with a simple configuration using a measurement electrode attached to a conductor, such as a metallic rod or human body, and a compensation circuit that compensates for parasitic capacitive components, allowing for accurate measurement without the need for double-electrode probes, using negative impedance converters or variable inductors for enhanced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a double-electrode capacitive voltage probe is used to measure common-mode voltage from the cable outer surface, then measurement capability is achieved, but the apparatus becomes bulky and complex
Solution Approach 1:
The invention extracts only the essential measurement function from the complex double-electrode probe structure. By using a single measurement electrode attached to a conductor that contacts the cable coating, the patent eliminates the need for the intricate inner and outer electrode arrangement while maintaining the ability to measure common-mode voltage from the cable outer surface
Solution Approach 2:
The invention introduces a conductor as an intermediary element between the measurement electrode and the cable. This conductor (such as a metallic rod or the human body) serves as a medium to transfer the capacitive coupling effect from the cable coating to the measurement electrode, enabling measurement without direct cable contact and simplifying the overall apparatus structure
2Measurement precision
If a double-electrode capacitive voltage probe is used to measure common-mode voltage, then measurement accuracy is achieved, but the apparatus becomes heavy and less portable
Solution Approach 1:
The invention removes the heavy and complex double-electrode probe structure and retains only the essential measurement functionality. The single measurement electrode attached to a lightweight conductor dramatically reduces apparatus weight while maintaining the ability to measure common-mode voltage accurately from the cable outer surface
Solution Approach 2:
The invention utilizes the human body or a simple metallic rod as the conductor, leveraging naturally available conductive elements rather than requiring specialized heavy equipment. This self-service approach reduces apparatus weight and improves portability while maintaining measurement capability
3Device complexity
If a simple measurement electrode configuration is used, then apparatus simplicity is achieved, but parasitic capacitive components reduce measurement accuracy
Solution Approach 1:
The invention employs a compensation circuit that provides feedback to counteract the parasitic capacitive components. By measuring the parasitic capacitance between the measurement electrode and the conductor, and applying compensating signals through the compensation circuit, the system maintains high measurement accuracy despite the simplified electrode configuration
Solution Approach 2:
The invention creates an equivalent circuit model that copies and represents the parasitic capacitive effects. By modeling the parasitic capacitance and incorporating it into the measurement system through the compensation circuit, the patent can accurately compensate for these effects and maintain measurement precision with a simple electrode configuration
4Measurement precision
If a complex double-electrode probe structure is used, then measurement capability is achieved, but manufacturing cost increases
Solution Approach 1:
The invention extracts only the essential measurement function from the expensive double-electrode probe structure. By using a single measurement electrode and a simple conductor, the patent dramatically reduces manufacturing costs while maintaining the ability to measure common-mode voltage from the cable outer surface
Solution Approach 2:
The invention replaces the expensive, complex double-electrode probe with inexpensive, simple components such as a basic measurement electrode and a readily available conductor (metallic rod or human body). This substitution significantly reduces manufacturing costs while maintaining measurement functionality
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 solution enables accurate and sensitive common-mode voltage measurement with a simpler, smaller, and lighter apparatus, capable of operating in a wide frequency range and compensating for parasitic components, thus improving measurement efficiency and reducing costs.
Implementation Method 1
a capacitive voltage probe having a double-structured electrode... a capacitive component between the cable 105 and the inner electrode 101a is denoted by C
Implementation Method 2
using negative impedance converters or variable inductors for enhanced sensitivity
Implementation Method 3
the compensation circuit includes an inductor an inductance of which is variable, the inductor being configured to compensate for the parasitic capacitive component through series resonance with the parasitic capacitive component
Data Source
AI summary
A common-mode voltage measurement apparatus according to an embodiment includes a measurement electrode attached to a conductor capable of being brought into contact with a coated cable, a measurement circuit configured to measure a common-mode voltage generated in the cable, and a compensation circuit connected in series between the measurement electrode and the measurement circuit, the compensation circuit being configured to compensate for a parasitic capacitive component formed between the measurement electrode and the conductor.