HV Battery Insulation Resistance Detection Using Reference Resistor
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Solution Overview
Problem
Existing systems for detecting insulation resistance in high-voltage battery systems of electric vehicles are complex and require multiple components, necessitating a more efficient method to reduce component count and utilize existing energy sources.
Innovation Solution
The proposed device alternately connects a reference resistance in parallel with the insulation resistances of the high-voltage battery system, using the battery's energy to measure voltages after parasitic capacitances are recharged, allowing for the calculation of insulation resistance without an additional test source, and can switch between internal and external insulation resistance configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing insulation resistance detection systems are used, then insulation monitoring is achieved, but the system complexity and component count increase
Solution Approach 1:
The high-voltage battery serves dual functions: as the energy source for vehicle operation and as the test voltage source for insulation resistance measurement. The existing battery voltage is utilized for measurement purposes, eliminating the need for separate test voltage generation equipment and reducing overall system complexity.
Solution Approach 2:
The system uses its own operational resources (battery voltage and existing circuitry) to perform self-diagnosis of insulation resistance. The battery's own voltage serves as the test signal, and existing measurement circuits are repurposed for insulation monitoring, allowing the system to monitor itself without external assistance.
2Measurement precision
If additional test sources are used for measurement, then measurement accuracy is improved, but the number of components increases
Solution Approach 1:
The high-voltage battery is employed for both propulsion and measurement functions. The same battery that powers the vehicle also provides the test voltage for insulation resistance measurement, eliminating the need for separate test sources and reducing component count while maintaining measurement capability.
Solution Approach 2:
The system utilizes its own operational voltage for self-testing purposes. The battery's operational voltage serves as the measurement signal source, allowing the system to perform self-diagnosis without requiring additional external test equipment.
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 simplifies the detection process by utilizing the high-voltage battery as a test source, reducing component requirements and enabling accurate insulation resistance calculation, thereby enhancing monitoring efficiency.
Implementation Method 1
the energy store, the high-voltage battery, is used as a test source
Implementation Method 2
after the parasitic capacitances have been recharged
Implementation Method 3
the reference resistance is alternately connected in parallel with the insulation resistances
Data Source
Figure 1
AI summary
The device has a high-voltage battery (HV-bat) and a high-voltage component (HV-komp), for example in the form of an inverter, where the high-voltage component is connected with the battery terminals over a switchable sliding valve (S-main plus,S-main minus). A reference resistor (R-0) is provided with a voltage measuring device for detecting the voltage applied between the respective pole and the reference potential of the vehicle body. The reference resistor is selectively switchable at the pole of the high-voltage battery via a switch (S-iso plus,S-iso minus,S-aux).