Relay Controls
- Nita E
Due to new regulations, charging must now have a relay.
The relay is controlled by the charger interface board.
HV Relay Driver
This circuit is copied from the BMS carrier. PB0 is one of the two pins that must be enabled to activate the relay.
HV_PWR_RELAY_12V_SW will carry 12V once the load switch is enabled. This causes inrush current.
Maximum inrush current = C*dv/dt = 49.2e-6*0.9e6 = 44.2 A.
Typical inrush current = 49.2e-6*0.6e6 = 29.52 A.
Minimum inrush current = 49.2e-6*0.3e6 = 14.76 A.
This may trigger overcurrent protection on the load switch, but it should resume normal operation after the current settles after a few microseconds.
Load Switch
PB8 is the other pin that must be enabled to activate the relay. PB9 and PA3 are used for diagnostics (more information is in the data sheet).