Insulation Resistance Detection Using External Voltage Reference
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Solution Overview
Problem
Existing insulation problem detection technologies for vehicles, such as hybrid and electric vehicles, suffer from low accuracy due to fluctuations in voltage boosted by the voltage converter, leading to inaccurate measurement of insulation resistance and total voltage, which affects the detection of insulation issues.
Innovation Solution
A microcomputer-controlled insulation problem detection apparatus that measures insulation resistance by connecting a capacitor in series with the vehicle's power supply and ground, obtaining the total voltage from an external apparatus, and using this information to accurately detect insulation problems, while also accounting for changes in boost voltage to prevent false detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the flying capacitor is charged by the total voltage of the power supply to measure insulation resistance, then the insulation resistance can be detected, but the measurement accuracy decreases due to voltage fluctuations from the voltage converter
Solution Approach 1:
The voltage detecting circuit performs preliminary action by obtaining the total voltage of the power supply before charging the flying capacitor. This preliminary voltage acquisition allows the system to compensate for voltage fluctuations during the measurement process, thereby maintaining measurement accuracy despite instability in the power supply voltage
Solution Approach 2:
The system implements feedback by using the obtained total voltage information to correct and refine the insulation resistance measurement. The voltage detecting circuit continuously monitors and adjusts measurements based on the actual power supply voltage, ensuring accurate detection even when voltage fluctuates during the measurement process
2Productivity
If the flying capacitor voltage is measured at different time points to detect insulation problems, then the detection process can be completed, but false detections increase due to boost voltage changes
Solution Approach 1:
The system performs preliminary action by obtaining the total voltage of the power supply at the same time point when the flying capacitor voltage is measured. This simultaneous data acquisition ensures that the voltage reference corresponds exactly to the measurement moment, eliminating errors caused by voltage changes between separate measurement times and preventing false detections
Solution Approach 2:
The voltage detecting circuit implements periodic action by synchronizing the voltage measurement with the insulation resistance detection cycle. Both the total voltage acquisition and flying capacitor measurement occur within the same detection period, ensuring consistent timing and preventing false positives due to voltage fluctuations between periodic measurements
3Device complexity
If the total voltage of the power supply is measured internally to maintain system integration, then device complexity increases, but external voltage acquisition adds communication overhead
Solution Approach 1:
The voltage detecting circuit implements universality by serving multiple functions: it detects both the total voltage of the power supply and the flying capacitor voltage, and performs both insulation resistance measurement and power supply voltage monitoring. This multi-functionality eliminates the need for separate measurement systems, reducing overall device complexity while maintaining efficient data acquisition
Solution Approach 2:
The microcomputer acts as an intermediary by centrally managing both the voltage detection circuit and the data processing. It coordinates the simultaneous acquisition of total voltage and flying capacitor voltage, processes both data streams, and performs the insulation resistance calculation, thereby simplifying the system architecture and reducing communication overhead through centralized control
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 solution enhances the accuracy of insulation problem detection, reduces false positives, and shortens the detection time by using external voltage data to stabilize measurements and offset the influence of boost voltage fluctuations.
Implementation Method 1
control a voltage detecting circuit to measure an insulation resistance of a vehicle based on a voltage at which a capacitor in the vehicle is charged
Implementation Method 2
measure an insulation resistance of a vehicle based on a voltage at which a capacitor in the vehicle is charged
Data Source
AI summary
An insulation problem detection apparatus includes a microcomputer configured to: control a voltage detecting circuit to measure an insulation resistance of a vehicle based on a voltage at which a capacitor in the vehicle is charged, the microcomputer controlling the voltage detecting circuit to connect the capacitor in series to a power supply mounted in the vehicle and a ground of a body of the vehicle to measure the voltage at which the capacitor is charged; obtain a total voltage of the power supply from an external apparatus that is external to the microcomputer when the insulation resistance of the vehicle is measured by the voltage detecting circuit; and detect whether there is an insulation problem of the vehicle based on (i) the total voltage of the power supply obtained from the external apparatus and (ii) the insulation resistance of the vehicle measured by the voltage detecting circuit.