Hybrid Cooling System Description and Operation
Hybrid Cooling System Description and Operation
This vehicle is equipped with three fully independent cooling systems. The power electronics cooling system is dedicated to cooling the drive motor battery charger and the drive motor generator power inverter module. The battery cooling system is dedicated to cooling and heating the high voltage battery. The engine cooling system is dedicated to cooling the engine and providing heat to the passenger compartment. Refer to On-Board Charge Module Description and Operation, Traction Power Inverter Module Description and Operation, and Accessory Power Module Description and Operation.
Power Electronics Cooling System Description and Operation
The primary purpose of the power electronics cooling loop is to cool the drive motor generator power inverter module, while propulsion is enabled, and the on-board charge module, when it is plugged in. The power electronics cooling system uses the power electronics radiator, the two 12 V pulse width modulated (PWM) radiator fans, a 12 V power electronics coolant pump to cool down the drive motor generator power inverter module and the drive motor battery charger. The hybrid/EV powertrain control module 2 activates the coolant pump and monitors a temperature sensor in the power electronics radiator. The hybrid/EV powertrain control module 2 monitors the power electronics cooling system temperature to determine when to operate the radiator fans. The coolant pump will be activated when the vehicle is on and during charging. The power electronics radiator is combined with the battery radiator to form one radiator. The power electronics coolant pump and radiator cooling fans will also be enabled during an after-run event which is determined by coolant loop temperature.
The power electronics cooling system circulates a pre-mixed DEX-COOL(R) which is a 50/50 mixture of DEX-COOL(R) and de-ionized water. De-ionized water is required for high voltage isolation and to prevent corrosion from effecting heat sink performance. Always use pre-mixed coolant and never use tap water in the power electronics coolant system.
Battery Cooling System Description and Operation
The energy storage system cooling system uses a battery radiator, the two 12 V pulse width modulated (PWM) radiator fans, a 12 V battery coolant pump, a refrigerant/coolant heat exchanger (chiller), the electric A/C compressor motor control module assembly, refrigerant pressure and temperature sensors, ambient air temperature sensor, and a hybrid/EV battery pack coolant flow control valve to cool down the high voltage battery. There is also a high voltage heater inside the battery to heat the coolant entering the battery when needed. The hybrid/EV powertrain control module 2 monitors the battery coolant temperature, battery cell temperature, refrigerant temperature and refrigerant pressure. The hybrid/EV powertrain control module 2 determines how much battery cooling or heating is required and turns on the coolant pump, positions the coolant flow control valve and depending on what is required will operate the radiator fans, request the A/C Compressor Module to turn on the high voltage A/C compressor, or turn on the high voltage heater. The battery cooling system could be activated when the vehicle is on or during charging. Refer to Air Conditioning Control Module Description and Operation.
The battery cooling system circulates a pre-mixed DEX-COOL(R) which is a 50/50 mixture of DEX-COOL(R) and de-ionized water. De-ionized water is required for high voltage isolation and to prevent corrosion from effecting heat sink performance. Always use pre-mixed coolant and never use tap water in the battery coolant system.
Engine Cooling System Description and Operation
Engine Coolant Bypass Valve (Powertrain Heater Bypass Valve/Three-Port Valve) and Coolant Heater Pump
The engine coolant bypass valve is also controlled by hybrid/EV powertrain control module 2 to assist in regulating passenger compartment comfort based on presence or absence of engine heat. Refer to Coolant Heater Control Module Description and Operation.
The engine cooling system uses the engine radiator, the two 12 V pulse width modulated (PWM) radiator fans, a 12 V coolant heater pump, a coolant flow control valve, a high voltage heater and a heater core. The hybrid/EV powertrain control module 2 operates the two radiator fans in response to engine temperature.
The coolant flow control valve has two positions. When commanded in bypass mode, as when the engine is OFF, the valve separates the engine and the cabin heater coolant loops to prevent heat generated by the cabin heater for passenger compartment from dissipating into the engine coolant loop. After the engine starts up and can allow excess engine heat to assist the cabin heater in heating the passenger compartment, the valve is commanded to link mode and the two coolant loops are connected.
The HVAC control module turns on the passenger compartment heater coolant pump and monitors the temperature sensors in the passenger compartment and coolant loop to determine if the high voltage heater is needed. Passenger compartment heat is provided by air flowing through the heater core. The heater core is heated by coolant from either, the engine, the high voltage heater or both. The hybrid/EV powertrain control module 2 will command the position of the coolant flow control valve to either isolate the passenger compartment heater loop from the engine coolant loop or link the two loops together.
The hybrid/EV powertrain control module 2 will command the engine coolant bypass valve into bypass mode when the module goes to sleep, at controller wake-up, and during other times except:
* During relearn (after extended loss of 12 V power to the controller)
* When the scan tool is sending a command.
* If the valve is stuck in an intermediate position (between two end positions) due to failure or debris.
The engine cooling system circulates a 50/50 mixture of DEX-COOL(R) and distilled water.
APM Cooling
The accessory power module is air-cooled. Refer to Accessory Power Module Description and Operation. The APM fan is powered by a brushless DC motor and has operating speeds between 0-3900 RPM. The fan is serviced separately from APM assembly. The hybrid/EV powertrain control module 2 will command the accessory power module fan while in RUN mode.