Maintain the overcurrent protection circuit of the electric vehicle charger

The maintenance of the overcurrent protection circuit of electric vehicle chargers should start from four aspects: functional detection, component maintenance, environmental adaptability guarantee and fault handling. The following are specific measures:

Function detection and verification

Regular simulation testing: Every 6 to 12 months, use professional equipment to simulate overcurrent scenarios to verify whether the protection circuit can promptly cut off the power supply and trigger an alarm when the current exceeds the threshold (such as 10A for 320ms).

Recovery function verification: After triggering the protection, check whether the circuit can automatically recover after disconnecting the load or charger to ensure that the protection logic has no locking faults.

Environmental adaptability test: Test the protection function in high-temperature (40℃) or low-temperature (0℃) environments to ensure that temperature changes do not affect the circuit performance.

Component maintenance and replacement

Inspection of the current detection unit: Focus on checking the accuracy of the current Hall sensor or sampling resistor. If the deviation of the detection value exceeds ±5%, it needs to be replaced immediately.

Overcurrent protection unit calibration: Check the parameters of components such as comparators, amplifiers, and clamping diodes to ensure that the overcurrent threshold (such as 10A) and delay time (such as 320ms) meet the design requirements.

Control unit update: For circuits controlled by MCU, firmware updates need to be made regularly to fix logic vulnerabilities, and current detection errors should be corrected through calibration tools.

Environmental and heat dissipation management

Cooling system cleaning: Regularly clean the dust from the charger's heat dissipation holes to ensure that the fan or heat sink is not clogged, preventing the protection circuit from malfunctioning due to overheating.

Temperature monitoring: Monitor the circuit temperature during overcurrent testing. If it exceeds 85℃, optimize the heat dissipation design or reduce the ambient temperature.

Fault handling and recording

Fault classification and processing:

Charging current failure: Immediately cut off the output and report the fault. Check the current detection unit and control unit.

Overvoltage/over-temperature/low-temperature fault: After delayed measurement, if the battery level does not reach 100%, the output will be cut off and a fault will be reported.

Maintenance record archiving: Detailed records of the current value, trigger time, ambient temperature and component replacement situation of each test are made, and maintenance files are established for traceability.