Leakage Impedance Detection Circuit for HV Battery Stacks
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Solution Overview
Problem
Existing methods for detecting leakage impedance in high voltage stacks of direct current voltage sources, such as batteries in hybrid vehicles, are costly and prone to measurement errors, posing a potentially life-threatening hazard due to faulty circuit components or insulation issues.
Innovation Solution
A system comprising a detection circuit with amplifiers, an analog-to-digital converter, and a processor that samples voltage signals to calculate leakage impedance and offset voltage, comparing these values to thresholds to generate notifications for potential hazards, utilizing a pair of amplifiers in inverting configurations and an isolated power supply to accurately identify leakage paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If previous methods are used to determine leakage impedance and location, then detection capability is achieved, but cost is high and measurement errors are unacceptable
Solution Approach 1:
The patent introduces an intermediary measurement approach using a known test impedance connected between the battery stack and chassis. By measuring the voltage across this known impedance and applying Kirchhoff's laws, the system indirectly determines the leakage impedance and location without requiring direct complex measurements. This intermediary method reduces measurement errors while maintaining reliability and reducing cost.
2Measurement precision
If complex detection systems are used to accurately identify leakage paths, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential measurement function by using a simple test impedance and voltage measurement setup, separating the complex leakage detection problem into manageable components. Instead of using a complex detection system, the invention extracts only the necessary elements (test impedance, voltage measurements, and calculations based on Kirchhoff's laws) to achieve accurate leakage identification, thereby reducing device complexity while maintaining measurement precision.
3Device complexity
If simple detection methods are used, then device complexity is reduced, but measurement errors become unacceptable
Solution Approach 1:
The patent implements a feedback-based calculation system where voltage measurements across the test impedance are continuously monitored and processed using Kirchhoff's laws to determine leakage impedance and location. The system uses the measured voltage values as feedback to calculate the leakage parameters, ensuring measurement precision is maintained while keeping the device complexity low. The feedback loop allows accurate determination of leakage conditions through systematic calculation rather than complex hardware.
Data Source
AI summary
A circuit, system, machine-readable storage medium and method for detecting the presence of a leakage path in a multi-cell voltage source is described. The system includes a detection circuit, the detection circuit having a first, second and third amplifiers, a first input of the first amplifier connected to a first terminal of the voltage source and the first input of the second amplifier connected to a second terminal of the voltage source, a second input of each of the first and second amplifiers connected to a reference capacitor, and an output of each of the first, second and third amplifiers connected to a respective first, second and third outputs of the detection circuit; and a processor having inputs connected to the first and second outputs of the detection circuit.