Isolating Transformer Insulation Detection via Pulse Current Sensing
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Solution Overview
Problem
Power electronic devices with high-frequency and high-power density transformers face challenges in detecting insulation state due to increased electric field stress, leading to partial discharge and early failure, with existing methods being inefficient and costly.
Innovation Solution
A method and device that utilize a detection loop with an excitation source, converter, connection element, and coupling impedance to detect pulse current signals, processing them to output partial discharge information, avoiding high-frequency electromagnetic interference by controlling main power switches and using existing power sources, thereby simplifying and cost-effectively assessing the insulation state of isolating transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the operating frequency of the main power transformer is increased to reduce volume and weight, then the volume and weight of the transformer are reduced, but the electric field stress on the insulation structure increases, leading to higher partial discharge risk
Solution Approach 1:
The patent applies preliminary action by performing insulation detection before partial discharge occurs. The detection method monitors insulation resistance and detects early signs of insulation degradation through pulse current measurement, enabling preventive maintenance before actual partial discharge damages the insulation. This allows the transformer to operate at high frequency with reduced volume while maintaining reliability through early fault detection.
2Measurement precision
If conventional partial discharge detection methods are used, then partial discharge can be detected, but the detection system becomes complex and costly due to additional excitation sources and high-frequency interference
Solution Approach 1:
The patent applies universality by making the existing power source serve dual functions: both powering the converter and providing the excitation signal for insulation detection. The control unit multiplexes the power source to generate detection pulses during idle periods, eliminating the need for separate excitation sources. This reduces detection system complexity while maintaining partial discharge detection accuracy through intelligent use of existing system resources.
Solution Approach 2:
The patent applies self-service by enabling the converter's own power source and control unit to perform insulation detection without external检测设备. The control unit utilizes the existing power circuitry and switching elements to generate detection pulses and measure insulation resistance, making the system self-diagnostic. This eliminates complex external detection equipment while maintaining detection precision through integrated measurement capabilities.
3Productivity
If main power switches are operated during detection, then the converter functions normally, but high-frequency electromagnetic interference contaminates the partial discharge signal
Solution Approach 1:
The patent applies periodic action by scheduling insulation detection during idle periods when main power switches are not operating. The control unit detects insulation resistance and monitors for partial discharge only during intervals when the converter is not switching power, creating periodic detection cycles. This timing strategy eliminates high-frequency electromagnetic interference from the detection signals while maintaining overall converter productivity through continued operation during non-detection periods.
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 approach reliably and efficiently detects insulation state without additional excitation sources, reducing electromagnetic interference and costs, enabling timely identification of partial discharge and potential failures in power electronic devices.
Implementation Method 1
Partial discharge causes deterioration of the insulation material, molecular degradation and carbonization
Implementation Method 2
detecting a pulse current signal of the connection element; and processing the pulse current signal and outputting a partial discharge information
Data Source
AI summary
The disclosure discloses a method and device for detecting insulation state in a conversion system, wherein the conversion system includes an excitation source, a converter having an input end coupled to the excitation source, a connection element coupled between an output end of the converter and a reference point, and a coupling impedance having a first end coupled to the excitation source and a second end coupled to the reference point, the method for detecting insulation state including steps of: S1, controlling at least one main power switch of the converter not to switch; S2, detecting a pulse current signal of the connection element; and S3, processing the pulse current signal and outputting a partial discharge information, the partial discharge information indicating an insulation state of an isolating transformer in the converter. The disclosure can overcome electromagnetic interference of high frequency steep waves on a partial discharge signal.