Insulation Detecting Circuit for Power Converters
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Solution Overview
Problem
Power converting devices in solar power systems face grounding failures leading to leakage currents, which can result in device failure or accidents, necessitating a reliable ground impedance detection mechanism to ensure normal operation.
Innovation Solution
An insulation detecting circuit with switching units, a detecting resistor, and a processing unit that calculates insulation impedance by measuring voltage values across the resistor in different operational modes, providing a ground impedance detection function to prevent accidents and ensure device safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ground impedance detecting function is added to the power converting device, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The insulation detecting circuit merges the detection function with existing power conversion components. The switching units S1 and S2 are integrated with the power conversion circuitry, and the detecting resistor Rd is incorporated into the existing circuit topology. This combining approach enables ground impedance detection without adding completely separate detection equipment, thus improving safety while limiting the increase in device complexity.
Solution Approach 2:
The switching units S1 and S2 serve dual purposes: they perform normal power conversion switching functions and simultaneously enable insulation detection by connecting the detecting resistor Rd to different circuit nodes. This multi-functionality allows the same components to fulfill both power conversion and safety detection roles, avoiding additional dedicated detection hardware and reducing overall device complexity.
2Measurement precision
If voltage values are measured across the detecting resistor in different switching modes, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The insulation detection process uses periodic switching actions where the switching units S1 and S2 alternately connect the detecting resistor Rd to different circuit nodes. By measuring voltage values during different switching periods or modes, the system achieves precise ground impedance measurement. The periodic nature of this detection allows accurate measurements to be obtained during normal operation cycles without requiring continuous high-energy detection states.
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 effectively detects insulation impedance, preventing device failures and accidents by accurately determining ground impedance values, reducing power loss, and enhancing detection accuracy and speed, while maintaining system efficiency.
Implementation Method 1
The processing unit is configured to operate in a first mode and calculate an insulation impedance value of a power converting device according to the first voltage value and the second voltage value
Data Source
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Figure 3A~3B
AI summary
An insulation detecting circuit (160) includes a first switching unit (S1), a second switching unit (S2), a detecting resistor (Rd), a processing unit (162), and a voltage detecting unit (164). The second switching unit (S2) is electrically coupled to the first switching unit (S1). The processing unit (162) is configured to control the first and the second switching units (S1, S2). The voltage detecting unit (164) obtains a first voltage value across the detecting resistor (Rd) when the processing unit (162) controls the first switching unit (S1) to be on and the second switching unit (S2) to be off. The voltage detecting unit (164) obtains a second voltage value across the detecting resistor (Rd) when the processing unit (162) controls the first switching unit (S1) to be off and the second switching unit (S2) to be on. The processing unit (162) operates in a first mode and configured to calculate an insulation impedance value of a power converting device (100) according to the first and the second voltage values.