Converter Insulation Detection via Switch-Controlled Impedance Reduction
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Solution Overview
Problem
In medium-high voltage converters, the detection of insulation failure is hindered by high impedance in the detection circuit, leading to weak signals and reduced reliability, especially under high electric field stress, which can cause accidents.
Innovation Solution
The method involves turning on switches in the detection circuit to reduce impedance, using an excitation source connected to the transformer, and employing a coupling impedance network with components like resistors, inductors, and capacitors to enhance signal intensity, allowing for effective insulation state monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If insulation detection is performed when the converter is in standby mode with switches turned off, then interference from converter operation is avoided, but the detection circuit impedance becomes high and signal intensity is weakened
Solution Approach 1:
The patent applies dynamics by making the switch states changeable during detection. Instead of keeping switches permanently off during standby detection, the method dynamically adjusts switch states to achieve optimal detection conditions. Specifically, switches are turned on during detection to reduce circuit impedance and enhance signal intensity, while being turned off during normal operation to avoid interference, thus resolving the contradiction between avoiding interference and maintaining signal strength.
2Reliability
If switches are turned on during detection to reduce impedance and enhance signal intensity, then detection reliability is improved, but converter operation interference may occur
Solution Approach 1:
The patent applies periodic action by implementing detection during specific time windows when the converter is in standby mode. The method periodically performs insulation detection at predetermined intervals, turning switches on only during these brief detection windows and turning them off during normal converter operation. This periodic switching strategy ensures detection reliability while minimizing interference from converter operation.
Solution Approach 2:
The patent applies preliminary action by performing insulation detection during standby mode before the converter starts normal operation. By completing the detection process while the converter is still in standby state and switches can be safely turned on, the system obtains accurate insulation data before potential interference from converter operation begins, thus ensuring detection reliability without suffering from operational interference.
3Volume of moving object
If the isolation transformer volume is decreased to achieve high power density, then the main insulation structure bears higher electric field stress, but this increases the risk of insulation failure
Solution Approach 1:
The patent applies feedback by implementing continuous insulation state monitoring through the detection method. The system periodically detects insulation conditions by analyzing current signals during standby mode, obtaining real-time feedback on insulation health. This feedback mechanism enables early detection of insulation degradation caused by high electric field stress in compact transformers, allowing preventive maintenance before failure occurs, thus maintaining reliability despite reduced transformer volume.
Solution Approach 2:
The patent applies self-service by enabling the converter system to monitor its own insulation status without requiring external detection equipment. The detection method utilizes the converter's existing switches, detection circuits, and control unit to perform self-diagnosis of insulation conditions. This self-monitoring capability is particularly valuable for compact high-power-density converters where external monitoring would add volume and complexity, allowing the system to maintain reliability through autonomous insulation assessment.
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 improves the sensitivity and reliability of insulation detection, enabling early identification of potential failures and reducing the risk of accidents without adding additional components, thus enhancing power density and efficiency.
Implementation Method 1
each of the n conversion units including a transformer including a primary winding and a secondary winding
Implementation Method 2
a coupling impedance network connected in series with the connection element and including at least one of a resistor, an inductor and a capacitor
Implementation Method 3
a coupling impedance network connected in series with the connection element and including at least one of a resistor, an inductor and a capacitor
Implementation Method 4
a coupling impedance network connected in series with the connection element and including at least one of a resistor, an inductor and a capacitor
Data Source
AI summary
The application discloses an insulation detection method and apparatus for a conversion system, the conversion system including: a converter module including n conversion units, where n≥1, each of the n conversion units including a transformer including a primary winding and a secondary winding; and a connection element connected between the primary winding and the secondary winding of the transformer; the insulation detection method including: controlling at least one switch of the converter module to turn on;detecting signals that reflect a current flowing through the connection element; and processing the signal and outputting insulation information, wherein the insulation information represents an insulation state of the conversion system.