Shielding-Type Insulation Detection With Split-Layer Differential Sensing
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Solution Overview
Problem
Conventional insulation structures in solid-state transformers struggle to accurately detect power frequency signals due to interference from high-frequency leakage currents, making it difficult to monitor insulation performance and preventing effective identification of insulation impedance.
Innovation Solution
A shielding-type insulation detection structure with a second shielding layer divided into two sub-layers, forming a bridge-type differential circuit, which suppresses high-frequency noise and allows for the acquisition of power frequency voltage signals through a detection circuit that measures the voltage difference between the sub-layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional insulation structure uses a single-loop sampling signal to detect insulation impedance, then the detection circuit can be simplified, but the high-frequency leakage current interferes with and masks the power frequency signal, making it impossible to identify the power frequency signal related to insulation impedance
Solution Approach 1:
The second shielding layer is divided into two separate sub-layers (first sub-layer and second sub-layer), creating two distinct detection branches. This segmentation allows the detection circuit to separately process signals from each sub-layer and then compute the differential voltage, effectively separating the power frequency signal from the high-frequency leakage current interference.
Solution Approach 2:
The patent introduces an intermediary detection mechanism that measures the voltage difference between the two sub-layers rather than directly measuring the insulation impedance. This intermediary approach (measuring voltage differential) serves as a mediator that converts the difficult-to-detect power frequency signal into a measurable voltage difference that is less susceptible to high-frequency interference.
2Measurement precision
If specific control methods are used to avoid high-frequency leakage current interference by enabling detection only when the high-frequency power element is not switched, then the interference is reduced, but the detection convenience is reduced and additional control mechanisms are required
Solution Approach 1:
The detection structure utilizes the existing operational states of the solid-state transformer without requiring additional control mechanisms. The bridge-type differential circuit continuously monitors the voltage difference between the two sub-layers, and the system automatically obtains accurate insulation information regardless of whether the high-frequency power element is switched or not, making the detection process self-service and convenient.
3Measurement precision
If the second shielding layer is divided into two sub-layers to form a bridge-type differential circuit, then the capability to suppress high-frequency noise is enhanced and power frequency voltage signals can be effectively acquired, but the device complexity increases
Solution Approach 1:
The second shielding layer is segmented into two sub-layers, which forms the basis of the bridge-type differential circuit. This segmentation enables the circuit to suppress high-frequency noise by measuring the differential voltage between the two sub-layers, as the high-frequency interference appears equally on both sub-layers and cancels out in the differential measurement.
Solution Approach 2:
The bridge-type differential circuit operates on the principle of equipotentiality, where the two sub-layers are maintained at similar potential levels under normal conditions. When insulation impedance changes occur, the potential balance is disturbed, creating a measurable voltage difference. This equipotential approach naturally rejects common-mode high-frequency interference while detecting differential power frequency signals.
Data Source
AI summary
A shielding-type insulation detection structure includes an input power source, a first shielding layer, a second shielding layer, a first impedance unit, a second impedance unit and a detection circuit. The first shielding layer is electrically connected with a first terminal of the input power source. The second shielding layer includes a first sub-layer and a second sub-layer. The insulation layer is disposed between the first shielding layer and the second shielding layer. The first impedance unit is electrically connected between the first sub-layer and a second terminal of the input power source. The second impedance unit is electrically connected between the second sub-layer and the second terminal of the input power source. The detection circuit is used to detect a detection signal related to a voltage difference between the first sub-layer and the second sub-layer of the second shielding layer.