Difference between CP Vs PP in EV Vehicles

CP vs PP in electric Vehicles

Control Pilot (CP)

The CP manages the actual charging process by establishing communication between the EV and the EVSE. It ensures that charging starts and stops safely, and it controls the amount of current delivered to the vehicle.

How it works:

Voltage Levels: The EVSE generates a square wave signal on the CP line. Different voltage levels of this signal represent different charging states:

• State A (Disconnected): +12V - No connection
• State B (Connected, EV Ready): +9V - Cable connected, EV ready to charge
• State C (Charging): +6V - Charging in progress
• State D (Charging with Ventilation): +3V - Charging with ventilation required (* NA in India*)
• State E (Fault): 0V or other abnormal voltage - Fault detected

Pulse Width Modulation (PWM): When in State C (Charging), the CP signal uses PWM to communicate the maximum available charging current from the EVSE to the EV. The duty cycle of the PWM signal (the proportion of time the signal is high) corresponds to the available current.

 

Key Functions:

• Connection confirmation
• EVSE current capacity advertisement
• Charging start and stop control
• Fault detection
• Ventilation request (if needed)

Proximity Pilot (PP)

The PP is primarily about connection detection and safety interlocks. It ensures that the charging cable is physically connected to the vehicle before charging can begin and prevents hazardous situations like driving off while still plugged in.

How it works:

Resistance: The EV applies a specific resistance across the PP pin and the Protective Earth (PE) pin. This resistance value is determined by a resistor in the charging cable.

Current Rating: The resistance value corresponds to the maximum current the cable can safely handle. This helps prevent overloading the cable.

Detection: The EVSE (charging station) detects this resistance. If the resistance is within the expected range, it confirms a valid connection.

Connector Locking (Type 1): In Type 1 connectors (common in North America), the PP also controls a mechanical locking mechanism that secures the connector to the vehicle during charging. This prevents accidental unplugging.

Connector Locking (Type 2): In Type 2 connectors (common in Europe and increasingly in India), the locking mechanism is separate, but the PP still provides the connection confirmation.

Key Functions:

• Cable connection detection
• Cable current rating identification
• Preventing drive-away during charging (connector locking)

Relationship between CP and PP

The PP and CP work together in a sequence:

Connection: The charging cable is plugged into the EV. The PP detects the connection and the cable's current rating.

Readiness: If the PP signal is valid, the EV signals its readiness to charge via the CP (State B).

Current Information: The EVSE uses the CP signal (PWM in State C) to inform the available charging current.

Charging: The EV's OBC (On-Board Charger) starts drawing current based on the advertised value.

Monitoring: Both CP and PP are continuously monitored during charging. If the PP signal is interrupted (e.g., the cable is unplugged), charging stops immediately. If the CP detects a fault, charging is also interrupted.

                                  

CP vs PP