Voltage Detection Circuit Resonant Inductive Coupling
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Solution Overview
Problem
The existing power transmission device's voltage detection method is prone to errors due to asymmetrical differential voltage and fails to accurately measure the differential voltage across the coupling coil, resulting in low detection accuracy and reliance on grounding one power transmission line.
Innovation Solution
A voltage detection circuit with a primary-side inductor and secondary-side inductor magnetic-field coupled, along with a secondary-side capacitor forming a resonant circuit, allows for direct detection of differential voltage between power transmission lines without referencing to ground, enhancing sensitivity by matching the resonant frequency with the alternating-current voltage and using combination resonance to reduce harmonic errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage divider is disposed between one power transmission line and ground to detect voltage, then the circuit structure is simple, but the detection accuracy is low due to asymmetrical differential voltage and inability to measure differential voltage across coupling coil
Solution Approach 1:
A coupling coil is introduced as an intermediary element between the power transmission lines and the detection circuit. The coupling coil magnetically couples to the main coupling coil, allowing indirect detection of the differential voltage across the main coupling coil without directly connecting to the asymmetrical power transmission lines, thereby eliminating measurement errors while maintaining circuit simplicity
Solution Approach 2:
Instead of directly measuring the differential voltage across the main coupling coil which suffers from asymmetry, a secondary coupling coil creates a copied version of the voltage signal through magnetic coupling. This copied signal can be measured accurately without being affected by the asymmetrical ground reference, achieving high detection accuracy without complex circuitry
2Measurement precision
If only the potential in one power transmission line is detected with reference to ground, then the circuit configuration is simplified, but the differential voltage applied across the coupling coil cannot be measured
Solution Approach 1:
The coupling coil serves as a mediator that transfers the differential voltage information from the power transmission lines to the detection circuit without requiring direct measurement of both line potentials. By magnetically coupling to the main coupling coil, it enables differential voltage measurement while keeping the detection circuit connected to ground at a single point, maintaining simplicity while achieving accurate differential measurement
3Measurement precision
If the resonant frequency of secondary-side resonant circuit is matched to the frequency of alternating-current voltage to be detected, then the sensitivity to detect voltage is enhanced, but the circuit requires precise frequency tuning
Solution Approach 1:
The resonant frequency of the secondary-side resonant circuit is adjusted as a key parameter to match the frequency of the alternating-current voltage to be detected. By tuning the resonant frequency parameter, the detection sensitivity is significantly enhanced through resonant amplification, while the adjustment can be achieved through simple component value selection rather than complex tuning mechanisms
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 detection of alternating-current voltage with high sensitivity across a wide frequency range, independent of line configuration, reducing measurement errors and maintaining stability and reliability.
Implementation Method 1
a primary-side inductor connected to the pair of input terminals, a secondary-side inductor magnetic-field coupled to the primary-side inductor
Implementation Method 2
a secondary-side capacitor connected in parallel to the secondary-side inductor, the secondary-side capacitor and the secondary-side inductor constituting a secondary-side resonant circuit
Data Source
AI summary
A voltage detection circuit includes an inductor connected to connection portions configured to input an alternating-current voltage, an inductor magnetic-field coupled to the inductor, a capacitor connected in parallel to the inductor and constituting a secondary-side resonant circuit with the inductor, and a voltage detector configured to detect an output voltage from the secondary-side resonant circuit. Therefore, a voltage detection circuit, a power transmission device, and a power transmission system capable of detecting an alternating-current voltage with high detection sensitivity irrespective of the potential of a power transmission line are provided.