Current Measuring Circuit for High-Voltage Sites
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Solution Overview
Problem
Current methods for measuring currents at high-voltage sites in high-frequency circuit systems, such as traveling-wave tubes, face challenges in accurately detecting small currents and are costly due to the use of expensive current sensors or transformers, which also complicate safe measurement and increase system costs.
Innovation Solution
A current measuring circuit that includes a current-detecting resistor and a differential amplifier with a transistor and resistors connected in series, allowing for proportional potential differences to be generated and measured, enabling accurate current detection without the need for expensive sensors or transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive current sensors or transformers are used to measure currents at high-voltage sites, then measurement precision is improved, but system cost increases
Solution Approach 1:
The patent replaces expensive current sensors or transformers with a simple voltage measuring circuit that uses inexpensive components (voltage divider, operational amplifier, ADC). This disposable-like approach uses cheap components to achieve the measurement function without requiring expensive specialized sensors, directly resolving the contradiction between measurement precision and system cost
Solution Approach 2:
The patent substitutes the mechanical/electromagnetic measurement system (current sensors, transformers) with an electrical measurement system based on voltage division and amplification. By measuring voltage instead of directly measuring current, the system avoids expensive current sensors while maintaining measurement capability through electrical signal processing
2Measurement precision
If current sensors or transformers are used for current measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex current sensors or transformers with a simple voltage measuring circuit using basic electronic components. This substitution dramatically reduces device complexity while maintaining measurement functionality, as the voltage-based approach requires only standard components rather than specialized measurement devices
Solution Approach 2:
The patent extracts the current measurement function from the complex domain of direct current sensing and transforms it into a voltage measurement problem. By taking out the direct current measurement requirement and converting it to voltage measurement through a current-to-voltage conversion circuit, the system achieves simpler measurement architecture
3Adaptability or versatility
If ammeter is used to measure currents at high-voltage sites, then measurement capability is achieved, but safety issues arise due to high voltage application
Solution Approach 1:
The patent introduces a voltage divider circuit as an intermediary between the high-voltage measurement point and the measurement instrument. This intermediary steps down the high voltage to a safe level before measurement, eliminating direct exposure to high voltage while maintaining measurement capability. The operational amplifier further isolates the measurement circuit from high voltage effects
Solution Approach 2:
The patent replaces the direct ammeter measurement method (which requires physical connection to high voltage circuits) with an indirect voltage-based measurement system. This substitution eliminates the safety hazards of direct high voltage connection while achieving the same measurement objective through electrical signal conversion
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 solution allows for accurate and cost-effective measurement of currents at high-voltage sites, reducing system costs and simplifying the measurement process while maintaining safety and precision.
Implementation Method 1
a current-detecting resistor inserted in series between a high-voltage site and an output terminal of a power circuit that supplies a predetermined direct voltage to the high-voltage site and that generates, between both ends thereof, a potential difference proportional to a current flowing through the high-voltage site
Implementation Method 2
a differential amplifier that amplifies the potential difference generated between both ends of the current-detecting resistor
Data Source
AI summary
A first resistor, a second resistor, a transistor, and a third resistor connected in series between a ground potential and an output terminal of a power circuit are provided. In addition, a current-detecting resistor is inserted in series between a high-voltage site and an output terminal of a power circuit that supplies a predetermined direct voltage to the high-voltage site. A differential amplifier controls a current flowing through the transistor so that a potential difference generated between both ends of the third resistor becomes proportional to a potential difference generated between both ends of the current-detecting resistor. At this point, by measuring the voltage of a connection node of the first resistor and the second resistor, the value of a current flowing through the high-voltage site can be calculated from the measured value.