Variable Capacitance Flying Capacitor for Insulation Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing insulation detecting devices for ungrounded direct-current power supplies in electric vehicles require long charge times for accurate voltage measurement, making them inefficient for quick or highly accurate measurements, especially after vehicle startup or for monitoring output voltage.
Innovation Solution
An insulation detecting device with a flying capacitor configuration that includes multiple capacitors connected in parallel, allowing for variable capacitance control via a parallel cancellation switch, enabling faster charging and discharging for quick measurements while maintaining high accuracy by switching between different measurement paths and capacitance settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flying capacitor with sufficiently larger capacitance than the Y capacitor is used to suppress the influence of electric charge from the Y capacitor, then measurement accuracy of ground fault resistance is improved, but charge time becomes extremely long
Solution Approach 1:
The patent applies dynamics by making the capacitance of the flying capacitor variable rather than fixed. The capacitance is dynamically adjusted based on the measurement mode: a larger capacitance value is used when measuring ground fault resistance to suppress Y capacitor influence, while a smaller capacitance value is used when measuring output voltage to reduce charge time. This dynamic adjustment resolves the contradiction between measurement accuracy and charge time.
Solution Approach 2:
The patent changes the capacitance parameter of the flying capacitor according to different measurement requirements. By selecting appropriate capacitance values from a set of available capacitances, the system optimizes both measurement accuracy and charge time for different measurement tasks, directly addressing the technical contradiction.
2Measurement precision
If a flying capacitor with large capacitance is used to suppress Y capacitor influence, then ground fault resistance measurement accuracy is improved, but the time required to charge to full charge or nearly full charge state becomes extremely long
Solution Approach 1:
The patent makes the capacitance duration dynamic by adjusting the capacitance value based on the measurement task. For ground fault resistance measurement where high accuracy is needed, a larger capacitance is used for a longer duration. For output voltage measurement where speed is important, a smaller capacitance is used to reduce charge duration. This dynamic control resolves the contradiction between measurement accuracy and charge duration.
Solution Approach 2:
The patent employs periodic switching between different capacitance values based on the measurement mode. The system periodically adjusts the capacitance configuration to match the current measurement requirement, allowing optimal performance for both accuracy-critical and time-critical measurements.
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 configuration allows for rapid and accurate measurement of output voltage and ground fault resistance, improving reliability and reducing detection time for abnormalities in the direct-current power supply, even under high voltage conditions.
Implementation Method 1
a flying capacitor configured to hold a charged voltage
Data Source
AI summary
An insulation detecting device includes a flying capacitor that holds a charged voltage, and a measurement and calculation unit that measures the charged voltage of the flying capacitor and calculates a ground fault resistance formed between a direct-current power supply electrically insulated from a ground, and the ground, based on the measured voltage. The flying capacitor includes one or a plurality of first capacitors, one or a plurality of second capacitors connected with the first capacitor in parallel, and a parallel cancellation switch arranged between the first capacitor and the second capacitor, and which performs parallel connection, and cancellation of the parallel connection, between the first capacitor and the second capacitor. A capacitance of the flying capacitor is variably changed by turning on or turning off of the parallel cancellation switch.