Charging System (Service Information): Operation

This vehicle can be equipped with a standard generator or a Smart Generator application:

STANDARD 

The Powertrain Control Module (PCM) uses the Generator field duty cycle signal circuit or F-terminal circuit, to monitor the duty cycle of the generator. The Generator field duty cycle signal circuit connects to high side of the field windings in the Generator. A Pulse Width Modulated (PWM) high side driver in the voltage regulator turns the field windings ON and OFF. The PCM uses the PWM signal input to determine the Generator load on the engine. This allows the PCM to adjust the idle speed to compensate for high electrical loads. The PCM monitors the status of the generator field duty cycle signal circuit. When the key is in the RUN position and the engine is OFF, the PCM should detect a duty cycle near 0 percent. However, when the engine is running, the duty cycle should be between 5-95 percent.

Courtesy of CHRYSLER GROUP, LLC

1 - Generator Field Circuit

2 - PCM

3 - Battery Sense Input

4 - Power Distribution Center (PDC)

5 - Battery

6 - Generator

7 - Resistor (Gasoline Engines Only)

8 - Generator Case Ground

9 - B+ Circuit (Generator Output)

10 - B+ Sense Circuit

11 - Starter

The charging system is turned on and off with the PCM (2) and ignition switch with engine running. The field circuit will not be energized until engine is running and ignition switch is on. This voltage is connected through the PCM (2) and supplied to the generator field circuit (1) at the back of the generator (6). The generator (6) is internally grounded through the generator case ground (8). The generator (6) regulates the field using Pin 1 of the field connector (High side driver).

The generator (6) is driven by the engine through a serpentine belt and pulley arrangement.

The PCM (2) receives a voltage input from the generator (6) via the B+ sense circuit (10) and also a battery sense input (3) from the Body Control Module (BCM) (4), it then compares the voltages to the desired voltage programed in the Electronic Voltage Regulator (EVR) software and if there is a difference it sends a signal to the generator EVR circuit to increase or decrease output. It uses PWM to send signals to the generator circuitry to control the amount of output from the generator. The amount of Direct Current (DC) produced by the generator is controlled by the EVR circuitry contained within the PCM (2).

All vehicles are equipped with On-Board Diagnostics (OBD). All OBD-sensed systems, including EVR circuitry, are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for certain failures it detects.

The Check Gauges Lamp (if equipped) monitors: charging system voltage,  engine coolant temperature and engine oil pressure. If an extreme condition is indicated, the lamp will be illuminated. This is done as reminder to check the three gauges. The lamp is located on the instrument panel.

Voltage is monitored at B+ sense circuit (10) to insure the cable is connected. If the B+ circuit (generator output) (9) cable is loose anywhere in the circuit the B+ sense circuit (10) will show high voltage. This condition causes the PCM (2) to shut down the generator field circuit (1). Because of this feature, pin 2 of the field connector is internally connected to the B+ circuit (9).

SMART GENERATOR: 

Smart Generator equipped vehicles operate under a strategy named the Smart Alternator Management (SAM). The SAM control strategy depends on the vehicle driving conditions and the battery status and is used to improve the vehicles fuel economy. The smart generator is a Local Interface Network (LIN) generator on diesel engine applications. On gasoline engine not equipped with the e-Torque system, the PCM with EVR is equipped.

The main strategy is:

• The smart generator set point voltage is regulated to the highest possible value in order to store part of the kinetic energy into the battery when the vehicle is decelerating
• The smart generator set point voltage is regulated to the lowest possible value in order to decrease the generators passive torque when high torque is requested during the acceleration and deceleration phases. The voltage set point is regulated in order to reach an optimal State of Charge (SOC)
• The smart generator voltage maximum limit and minimum limit are calculated based on the battery status and the vehicle electrical load activations

The SAM strategy used will depend on the trip profile of vehicle:

• Strong acceleration with high increase of requested torque (Passive Boost phase)
• Braking cut-off condition (Regenerative Braking phase)
• Vehicle state different from Passive Boost or Regenerative Braking (Steady State phase)
• Engine cranking phase (Optimized engine crank)
• Engine shut-off phase (Engine shutdown dynamic control)

During these phases the smart generators voltage is regulated dynamically. The maximum voltage and the minimum voltage limit depends on the vehicle system (battery SOC, temperature, various vehicle system electrical loads).

PCM  : The SAM system is implemented by the PCM, which is the smart generators LIN master. An example of PCM strategy implementation would be during the cranking phase to engine running state. When the driver changes the ignition to cranking mode, there are two sub phases of the SAM strategy implemented by the PCM:

• During the first phase the voltage set point will be set at low value, to reduce the torque and help the engine to start.
• In the second phase, after a specific Revolutions Per Minute (RPM) threshold the voltage set point must be set at a high value to reduce the RPM overshoot.

Once the engine has started, a "system running" SAM strategy is applied to the smart generator and remains until the engine is stopped. While the system is in the "system running" state, the Body Control Module (BCM) and PCM monitor certain conditions to determine voltage minimum output and the voltage maximum output to be used in the SAM strategies.

Driving condition detection is used by the SAM system to recognize if the vehicle is in one of three states:

• Passive Boost (drive condition 1)
• Steady State (drive condition 2)
• Regenerative Braking (drive condition 3)

This driving condition information is used to determine if the driveline is closed or if the driveline is open.

Driveline closed means:

• Neutral or drive clutch engaged. This information is determined by using Controller Area Network (CAN) signals received from the Transmission Control Module (TCM).

Driveline open means:

• Neutral or gear engaged

When an engine fault or its sensors or actuators do not permit drive condition recognition, the system defaults into the steady state drive condition 2.

The SAM strategy is assigned a value ranging 0-10. Each number value indicates a SAM strategy that the PCM specifically identifies and broadcasts on the CAN-Chassis (CAN-C) network data bus.

Charging system failures are managed by the PCM and this information is bussed over the CAN-C bus to the IPC for display. The smart generator is controlled by a EVR routine in the PCM. The EVR algorithm is able to recognize fault conditions and sends fault indication signals over the CAN-C data network.

By means of its own regulation system, the smart generator is able to recognize its own fault conditions and indicate them by setting specific LIN signals. The fault conditions that are managed depends on the regulator type and are as follows:

• Generator Fault Communication Error
• Generator Electrical Fault
• Generator Over Temperature Fault
• Generator Mechanical Fault
• Generator Communication Time Out Fault

Each of these faults are communicated by the PCM setting the appropriate DTC as well as broadcasting the proper fault indication signals over the CAN-C data network.

BCM  : The BCM has two SAM functions:

• It is the gateway for the battery status signals coming from the Intelligent Battery Sensor (IBS) to the Controller Area Network-Chassis (CAN-C) network
• It receives information from some vehicle loads and manages voltage limits by increasing or decreasing the generator voltage output. The battery voltage limits are monitored while these requested voltage changes are occurring. The BCM calculates the limits of the maximum charging voltage by utilizing a LIN bus message from the IBS indicating the battery temperature.

Depending on the state of some electrical loads and the maximum charging limit already calculated by the BCM, the BCM will set the minimum and maximum voltage limits for the generators target voltage. These limits are then broadcast on the CAN-C network.