Hybrid Cooling System Description and Operation
Hybrid Cooling System Description and Operation
Hybrid/EV Battery Pack Cooling
Within the hybrid/EV battery pack, the hybrid/EV battery section 1, hybrid/EV battery section 2, and starter/generator control module are air cooled. Air is drawn in by the hybrid/EV battery pack cooling fan from the vehicle's passenger compartment. This air travels through a series of ducts into the hybrid/EV battery pack. Once inside the hybrid/EV battery pack, the air travels through the hybrid/EV battery section 1 and hybrid/EV battery section 2. The internal battery cells of the hybrid/EV battery section 1 and hybrid/EV battery section 2 are arranged in a staggered manner that allows maximum cooling as air travels through the battery sections. The air is then drawn under the starter/generator control module. The underside of the starter/generator control module have a series of heat sinks that allowing cooling of the internal electronics and capacitors. Air exits the hybrid/EV battery pack through a duct and is drawn through the hybrid/EV battery pack cooling fan. From the fan, air is exhausted into the vehicle's rear compartment through a series of ducts.
The cooling needs of the hybrid/EV battery pack is determined through the use of a series of temperature sensors. Six temperature sensors are used to monitor the temperature of the hybrid/EV battery section 1 and hybrid/EV battery section 2 cell groups. The starter/generator control module commands the hybrid/EV battery pack cooling fan to provide more or less air as the battery temperature increases or decreases. A single temperature sensor is used to monitor the air temperature of the incoming cooling air.
The hybrid/EV battery pack cooling system contains the following serviceable components:
* Hybrid/EV Battery Pack Case
* Hybrid/EV Battery Section 1
* Hybrid/EV Battery Section 2
* Battery Energy Control Module
* Starter/Generator Control Module
* Hybrid/EV Battery Pack Cooling Fan
Hybrid/EV Battery Pack
The hybrid/EV battery pack is integral to the hybrid/EV battery pack cooling system. Foam gaskets are adhered to the metal battery pack tray. This seals the underside of the starter/generator control module to ensure proper airflow under the control module for cooling purposes. The hybrid/EV battery pack case cover also provides a mounting surface for the hybrid/EV battery pack cooling fan and has openings where the plastic vents are allowed to pass into the hybrid/EV battery pack to direct air through components which require cooling.
Hybrid/EV Battery Section 1 and Hybrid/EV Battery Section 2
The hybrid battery sections are air cooled. Each battery case has an air inlet and an air outlet. Air is drawn through the battery case to cool the individual cells. Six temperature sensors are used to monitor the battery temperature. The battery temperature sensors are located in the battery sections. Two of the temperature sensors are located on the top of the battery section and the remaining four are located on the bottom of the section. The temperature sensor is a variable resistor that measures the temperature of the battery cell group.
Battery Energy Control Module
The battery energy control module measures critical temperatures within the two battery sections and at the hybrid/EV battery section 1 air inlet. Six temperature sensors are used to monitor the battery temperature. The battery temperature sensors are located in the battery sections. Two of the temperature sensors are located on the top of the battery section and the remaining four are located on the bottom of the section. The temperature sensor is a variable resistor that measures the temperature of the battery cell group. The battery energy control module supplies 5 V to the signal circuit and a ground for the low reference circuit. The battery temperature sensor resistance changes with battery temperature. As the temperature decreases, the sensor resistance increases. As the temperature increases, the sensor resistance decreases. The air inlet temperature sensor operates in much the same way, except that it measures the temperature of the incoming air used to cool the hybrid/EV battery pack at the hybrid/EV battery section 1 air inlet. None of the temperature sensors or the temperature sensor harness is serviceable. They are all serviced as part of the battery sections.
Starter/Generator Control Module
The starter/generator control module uses temperature information from the battery energy control module to control the hybrid/EV battery pack cooling fan and increase or decrease the cooling capacity. As battery cell temperature increases, the start/generator control module will command the hybrid/EV battery pack cooling fan speed to increase, increasing the air flow through the hybrid/EV battery pack. The starter/generator control module may also command the fan on in low ambient temperatures to aid in the warming of the battery cells. If the ambient temperature of the air in the passenger compartment, where the cooling air is drawn from, is warmer than the battery cell temperatures, it may be used to help warm the cells more quickly. The starter/generator control module will used the air inlet temperature sensor to determine the temperature of the incoming air.
Hybrid/EV Battery Pack Cooling Fan
The hybrid/EV battery pack cooling fan draws air through the hybrid/EV battery pack to control the temperature of the hybrid/EV battery section 1, hybrid/EV battery section 2, and starter/generator control module. To operate, the cooling fan receives an enable signal from the starter/generator control module. The enable control is controlled by a discrete high side driver in the starter/generator control module. When the enable control circuit is high, the fan will be enabled. The fan speed is controlled by a pulsed high side driver in the starter/generator control module. The greater the duty cycle on the fan speed signal circuit, the higher the fan speed. Maximum fan speed is 3900 RPM. The hybrid/EV battery pack cooling fan provides a low-side drive, pulse-width modulated feedback signal to the starter/generator control module. During normal operation, this feedback signal provides fan speed information. The hybrid/EV battery pack cooling fan has limited self-diagnostic capability. If the fan determines there is an internal fault, it will provide this information on the feedback circuit.
Starter/Generator Cooling
The starter/generator is liquid cooling using a stand-alone cooling system that is separate from the engine's cooling system.
The starter/generator cooling system contains the following serviceable components:
* Starter/Generator Control Module
* Starter/Generator Coolant Temperature Sensor
* Starter/Generator Coolant Pump
Starter/Generator Control Module
The starter/generator control module monitors the starter/generator coolant temperature sensor. When the coolant temperature indicates that starter/generator cooling is required, the starter/generator control module commands the starter/generator coolant pump on. The starter/generator control module provides ground to the starter/generator coolant pump relay coil through a dedicated low side driver. The will cause the starter/generator coolant pump relay switch to closed, providing B+ to the starter/generator coolant pump.
Starter/Generator Coolant Temperature Sensor
The starter/generator coolant temperature sensor is a variable resistor that measures the temperature of the starter/generator coolant. The starter/generator control module supplies 5 V to the signal circuit and a ground for the low reference circuit. The starter/generator coolant temperature sensor resistance changes with starter/generator coolant temperature. As the temperature decreases, the sensor resistance increases. As the temperature increases, the sensor resistance decreases. The starter/generator control module monitors the starter/generator coolant temperature sensor to determine the temperature of the starter/generator coolant. As the coolant temperature changes, the starter/generator control module will turn the starter/generator coolant pump on or off to accommodate the starter/generator cooling requirements.
Starter/Generator Coolant Pump
The drive motor coolant pump is a single speed ON/OFF pump that circulates coolant through the starter/generator radiator and the starter/generator to control the temperature of the starter/generator.