EV Battery Insulation Detection Circuit for Relay Switch Safety
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Solution Overview
Problem
Current methods fail to effectively detect the insulation performance of the external sides of relay switches in electric vehicle power battery packs, leading to potential dangerous contacts due to undetected insulation faults.
Innovation Solution
A detection circuit and method that includes a controller, battery pack, main positive and negative switch modules, and detection loops, allowing for the collection and analysis of voltage values to determine the resistance values of insulation resistors on both internal and external sides of the switch modules, thereby assessing insulation performance and preventing dangerous contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional insulation detection methods are used, then the detection process is simple, but the insulation performance of external sides of switch modules cannot be effectively detected
Solution Approach 1:
The detection circuit segments the insulation detection into two separate detection loops: one for detecting insulation performance of the external side of the main positive switch module, and another for detecting insulation performance of the external side of the main negative switch module. Each detection loop independently measures insulation resistance to ground, enabling precise detection of external insulation performance without requiring complex integrated measurement systems.
Solution Approach 2:
The patent introduces detection loops with detection resistors and detection switches as intermediary elements between the battery pack terminals and the controller. These intermediaries enable the controller to indirectly measure insulation resistance by applying test voltages and measuring resulting currents, transforming an otherwise inaccessible insulation parameter into a measurable electrical quantity.
2Reliability
If insulation detection is performed with both switch modules turned off, then safety is improved, but the detection accuracy of external insulation resistance is reduced
Solution Approach 1:
The controller performs preliminary safety verification by detecting insulation resistance of internal sides of both switch modules before allowing either module to be turned on. Only when both internal insulation resistances exceed threshold values does the controller permit operation, ensuring safe initial conditions while enabling subsequent accurate external insulation measurement.
Solution Approach 2:
The detection system dynamically adjusts its operation mode: during normal operation, one switch module remains on while the other is off for detection; during safety verification, both are off. The controller dynamically selects which module to detect based on operational state, optimizing both safety and measurement accuracy at different times.
3Measurement precision
If one switch module is turned on for detection, then external insulation detection accuracy is improved, but the risk of dangerous contact increases
Solution Approach 1:
The controller applies preliminary anti-action by performing comprehensive internal insulation verification and establishing safe operational conditions before allowing external insulation detection with one switch module turned on. The system preemptively prevents dangerous states by ensuring both internal insulation resistances are adequate before permitting detection operations that could potentially create hazardous conditions.
Solution Approach 2:
The detection system implements continuous feedback monitoring where the controller measures insulation resistance values in real-time and compares them against preset threshold values. When insulation resistance drops below the threshold indicating potential danger, the controller immediately triggers protective actions to disconnect or alert, creating a closed-loop safety mechanism that dynamically responds to insulation conditions.
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 enables the detection of insulation performance on both sides of the switch modules, ensuring safe operation by identifying and preventing insulation faults, thus avoiding dangerous contacts between the power battery pack and ground.
Implementation Method 1
The controller is configured to obtain resistance values of insulation resistors of external sides of the main positive switch module and the main negative switch module, according to resistance values of insulation resistors of internal sides of the main positive switch module and the main negative switch module, as well as the voltages of the positive electrode and the negative electrode of the battery pack and the voltage between the external side of the main positive switch module and the external side of the main negative switch module
Data Source
AI summary
The present disclosure discloses a detection circuit and method. The detection circuit comprises: a controller, a battery pack, a main positive switch module, a main negative switch module and at least one detection loop. The controller collects voltages of a positive electrode and a negative electrode of the battery pack and a voltage between external sides of the main positive switch module and the main negative switch module when turning on the main positive or negative switch module and after turning on any detection loop, and obtains resistance values of insulation resistors of the external sides according to resistance values of insulation resistors of internal sides of the main positive and negative switch module, as well as the voltages of the positive electrode and the negative electrode and the voltage between the external sides of the main positive switch module and the main negative switch module, which are collected twice.