Principles of Operation

PRINCIPLES OF OPERATION

The high-voltage system has a floating ground. When the engine is operating or the vehicle is moving, the high-voltage generator generates high-voltage AC electricity. High-voltage AC electricity can be consumed or generated by the motor generator, the traction motor or a combination of both motors. Excess high-voltage current is converted from high-voltage AC to high-voltage DC electrical power inside the motor generator unit and transmitted through the high-voltage cables. The high-voltage DC electrical power is converted to low-voltage DC electrical power through the DC/DC converter. This low-voltage DC electrical power is then supplied to the 12-volt battery through the low-voltage battery cables.

12-Volt Battery
The 12-volt battery is a standard automotive battery. It is a DC source connected in a negative ground system. The battery case is sealed, with 2 vent holes to release gases. The battery has 3 major functions:
- Storage of electricity for later use
- Voltage stabilizer for the electrical system
- Temporary power source when electrical loads exceed the DC/DC converter output current

High-Voltage Traction Battery (HVTB)
The high-voltage traction battery (HVTB) is a 216-397 volt DC source connected in a floating ground system. The battery receives, stores and delivers high-voltage electrical power when required. It contains the traction battery control module (TBCM), which controls the higher functions of the battery. The TBCM also estimates the state of charge, estimates the power available and controls the battery temperature. The TBCM controls the battery temperature by activating or deactivating the fans contained within the HVTB, and by activating or deactivating the air conditioning system for the HVTB. For information about the hybrid climate control system, refer to Heating and Air Conditioning. Also contained within the HVTB is a low-voltage charger that is used during the jump start procedure. For information about the jump start procedure, refer to the Owner's Literature.

Motor Generator
The motor generator is contained in the electronically controlled continuously variable transmission (eCVT). It functions to generate high-voltage electricity and as the starter motor. The motor generator is connected to the HVTB with the high-voltage cables. The motor generator is an internal part of the eCVT and it cannot be repaired, only installed new as an assembly.

DC/DC Converter
The DC/DC converter is a liquid-cooled component that converts high-voltage (216-397 volt) DC power to low-voltage (12 volt) DC power while maintaining electrical isolation between the 2 DC power systems. The converter steps down the high-voltage to 12 volts, providing power to the vehicle low-voltage battery systems. The PCM controls the operation of the DC/DC converter through an enable input from the PCM to the DC/DC converter. Refer to Hybrid Drive Systems.

Regenerative Brakes
The regenerative braking system is designed to recapture some of the energy from braking. It accomplishes this through the use of the traction motor and motor generator, which recapture energy during braking. This recaptured energy is used to charge the HVTB. The regenerative brake system is a series system. A series system is one in which powertrain braking is used first, up to the limits of the powertrain torque capacity and battery capacity. After optimum regeneration is used, the friction brakes are applied to supplement braking demands. The series regenerative braking system also contains the ABS module within the same unit.