PHEV Electrified Powertrain System: Notes

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SYSTEM DESCRIPTION:

The Plug-in Hybrid Electric Vehicles (PHEV) can consist of the following components:

High Voltage Battery Pack Control Module (BPCM)
Power Inverter Module (PIM)
P1f or P1r electric motor used for starting/charging
Either a P2, P3 or P4 electric motor used for propulsion

The generic graphic below shows all possible electric motor combinations for PHEV vehicles.

This vehicle is equipped with the P1f / P2 electric motor combination. The P2 motor is located in the input of the electrified transmission assembly.

Courtesy of CHRYSLER GROUP, LLC

P1f - Electric Motor used for starting and charging the engine located at the front of engine (MGU)

P1r - Electric Motor used for starting and charging the engine located at the rear of engine

P2 - Electric Motor used for propulsion located in the transmission input

P3 - Electric Motor used for propulsion located at the rear of transmission or transfer case

P4 - Electric Motor used for propulsion located in the rear axle

Green - Starter Motor used with P1f motors on eTorque vehicles

SYSTEM OPERATION: This Plug-in Hybrid Electric Vehicle (PHEV) uses both a gasoline fueled internal combustion engine and a P2 electric 3-phase motor for propulsion. A high voltage direct current (DC) battery is used as the energy source for the electric motors. The PIM converts the high voltage DC power into AC power to drive the 3-phase electric motors. The PIM controls the interaction between the battery and the electric motors by controlling voltage, current, and frequency to control the torque applied to the P2 motor. The frequency of the three phase AC current being generated by the PIM is what controls the angular velocity of the output shaft. The amount of current directed to the electric motor is directly proportional to the torque generated at the output shaft.

The P2 electric motor can be coupled or de-coupled from the engine. This allows the vehicle powertrain to operate in the following operating modes:

Full Electric Mode - In full electric mode the P2 motor is de-coupled from the engine and the electric motor is propelling the vehicles powertrain. This is the preferred mode of operation when the high voltage battery is fully charged and all conditions for electrified powertrain are met.
Hybrid Mode - In Hybrid mode the P2 motor is coupled to the engine and the engine is started. The vehicles powertrain is propelled by the engine and the P1 motor is used to charge the battery. This mode is used when the high voltage battery state of charge is getting below a calibrated threshold and the battery is being charged.
Gas Engine Mode - The P2 motor is not being powered and the vehicle is propelled by only the gas engine. The vehicle will run in gas engine mode when there is an electrified powertrain failure but there are typically cluster warning messages for the system. This is basically a limp mode.

When charging of the high voltage battery is needed, the PIM provides AC power to drive the P1 motor and start the gas engine. In colder temperatures the P2 motor can also be used to assist the P1 motor in starting the engine. Unlike the P2 motor, the P1 motor is always coupled directly to the engine.

The vehicle also charges the high voltage battery during regenerative braking. During deceleration the P2 electric motor is used as a generator. This performs two functions:

Allows the energy created in the electric motor that is generated from the drivetrain to charge the high voltage battery.
The electric motor creates drag on the drivetrain to help slow the vehicle, reducing the amount of brake input required.

There are two modes of regenerative braking:

Coast down regeneration - The electric motor acts to gradually slow down the vehicle with minimum energy recuperated. The amount of coast regeneration is dependant on the creep-coast calibration curve. This is controlled completely by the Hybrid Control Processor (HCP) inside the PIM.
Brake regeneration - A higher amount of regeneration is possible. During light to moderate brake pedal application, only the electric motor is slowing the vehicle. No friction brake needed. With heavier brake pedal application, the conventional friction brakes also are applied. This requires coordination between the HCP and brake system module.

For detailed description and operation on the Battery System, refer to the Battery Pack Control Module (BPCM) Description and Operation.

For detailed description and operation on the PHEV Charging System, refer to the PHEV Charging Description and Operation in the High Voltage Battery Subsystem.

For detailed description and operation on the PHEV Starting System, refer to the PHEV Starting Description and Operation in the High Voltage Battery Subsystem.