Operation Description

WHEN HIGH-VOLTAGE SYSTEM IS CONNECTED 

When vehicle is READY, HPCM controls the system main relays and first applies current via the resistor, protecting the circuit from high-voltage inrush current.

System relay operation

1. Turns ON the pre-charge relay and system main relay 1, and applies current to the circuit via the resistor.

   At this time, the capacitors inside the traction motor inverter are charged. (Pre-charge)

   Fig 1: System Main Relay Operational Diagram (Pre-Charge Relay And System Main Relay 1 ON)

   Courtesy of NISSAN NORTH AMERICA, INC.
2. When the capacitors are charged, system main relay 2 turns ON and the pre-charge relay turns OFF, connecting the high-voltage circuit.
   Fig 2: System Main Relay Operational Diagram (Pre-Charge Relay OFF And System Main Relays ON)

   Courtesy of NISSAN NORTH AMERICA, INC.

WHEN HIGH-VOLTAGE SYSTEM IS DISCONNECTED 

When high-voltage system is disconnected, HPCM turns system main relay 2 OFF and discharges the capacitors inside the drive inverter (discharge). When discharge is completed, main relay 1 turns OFF, disconnecting the high-voltage circuit.