Drive Motor Generator Battery Identification Information
Drive Motor Generator Battery Description
Drive Motor Generator Battery Description
This system contains twenty-two plastic battery modules of ten cells each for a total nominal system voltage of 198-320 V.
The drive motor generator battery is also referred to as the hybrid battery. The drive motor generator battery contains 22 individual battery modules. Each battery module is rated at 12.2 V direct current (DC) and all the modules are connected together in series. The combined output voltage of all the modules is 198-320 V DC. The DC high voltage (HV) connects to drive motor generator power inverter module through HV DC cables that route underneath the vehicle. The HV battery positive and negative cable assembly (300 V) is always colored orange to denote the potential for high voltage. The drive motor generator power inverter module converts the DC voltage to alternating current (AC) voltage to enable the electrical portion of the powertrain hybrid functions. The drive motor battery coolant fan, the drive motor battery coolant pump are used to cool the batteries. The drive motor generator control module controls these devices and monitors current, voltage and temperature by using several sensors within the drive motor generator battery assembly. The drive motor generator battery control will set diagnostic trouble codes based on these inputs.
Location
The drive motor generator battery is located in the load floor behind the rear seat. The drive motor generator battery control module, drive motor battery coolant fan, the drive motor battery coolant pump, current limit relay, and HV contactors are located within the drive motor generator battery assembly.
Drive Motor Generator Battery Control Module
State of Charge
The drive motor generator battery control module uses a complex calculation method based on varying conditions over a range of operation to determine and update the state of charge (SOC) of the drive motor generator battery. The drive motor generator battery parameters used by the drive motor generator battery control module include current, voltage, and temperature. These inputs are monitored by several sensors within the drive motor generator battery assembly.
Operating Functions
The drive motor generator battery control module. In order to maintain proper state of charge levels and operate efficiently, the hybrid drive motor generator battery has several systems that need to be monitored and controlled. These systems include hybrid battery voltage measurement, hybrid battery current measurement, hybrid battery cooling and the high voltage interlock loop system. Additionally, the drive motor generator battery control module operates the high voltage contactors at the request of the drive motor generator control module. The drive motor generator battery control module is located within the drive motor generator battery assembly.
Communication and Hosted Diagnostics
The drive motor generator control module is the host controller for diagnostic trouble code (DTC) information for the following control modules:
* The drive motor generator power inverter module
* The drive motor generator battery control module
* The accessory DC Power Control Module
* Motor control module (MCM) 1
* Motor control module (MCM) 2
* Auxiliary transmission fluid pump (ATFP) control module
The drive motor generator battery control module will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the drive motor generator battery control module to the drive motor generator control module through the communication circuit.
In the event a hosted module communicates a fault condition, the drive motor generator control module will determine if hybrid operation is affected and notify the vehicle operator by requesting the MIL illuminate and/or by displaying the SERVICE HYBRID SYSTEM message. In addition, the drive motor generator control module will store the associated DTC information for retrieval by a scan tool. Some hosted modules may require an ignition cycle to clear certain DTCs from the drive motor generator control module.
Input Circuits - Voltage Measurement
The drive motor generator battery control module monitors the voltage values of the hybrid batteries using 3 different methods. The drive motor generator battery control module monitors the sum of the voltage at 22 battery locations, and sums up these values to generate a calculated voltage value. The drive motor generator battery control module also measures high voltage when the contactors are closed by monitoring the total bus voltage from the harness on the output side of the positive and negative HV contactors, this is the terminal voltage measurement. The total hybrid battery pack voltage is measured using a voltage sensor.
Input Circuits - Hybrid Battery Current Measurement
The drive motor generator battery control module monitors current through the hybrid battery current sensor. The hybrid battery current sensor is mounted on the positive cable side internal to the hybrid drive motor generator battery assembly. The current sensor detects the amperage that flows in and out of the hybrid batteries. The current sensor inputs a voltage between 0-5 V in proportion to the amperage. A reading of 2.5 V is 0 A.
Input Circuits - Hybrid Battery Temperature
The drive motor generator battery is cooled by the drive motor battery coolant fan, the drive motor battery coolant pump. The drive motor battery coolant fan and the drive motor battery coolant pump are located inside the drive motor generator battery assembly and controlled by the drive motor generator battery control module. The drive motor generator battery control module monitors four hybrid battery temperature sensors, an air inlet temperature sensor, and a coolant temperature sensor. These temperature sensors are internal to the drive motor generator battery assembly and are located between the hybrid batteries. The resistances of these temperature sensors decrease as temperature increases. The drive motor generator battery control module can command the coolant fan and pump based on vehicle speed and temperature.
Input Circuits - High Voltage Interlock Circuit (HVIL)
The vehicle is equipped with a high voltage interlock circuit (HVIL) feature. The purpose of the HVIL is to detect attempted access to HV components when HV is present. The drive motor generator battery control module supplies and monitors current on a 2 wire circuit that runs through certain HV components and their access points. The drive motor generator battery control module will take action based on the results of the measured current at both the input and output circuits. Additionally, the drive motor generator power inverter module monitors the HVIL and will also take action based upon the following.
* Measured current.
* HV contactor command (PWM).
* Hybrid ACC.
* Hybrid communication circuit.
* Controller 12 V.
* Thermal 12 V system.
Output Circuits - High Voltage Contactors
There are 2 HV contactors and a current limit relay, the positive HV contactor , the negative HV contactor and the current limit relay, also called the precharge relay. The HV contactors, control the high voltage battery negative and positive circuits and isolate the hybrid battery voltage from the rest of the vehicle. The drive motor generator battery control module will close the HV contactors only at the request of the drive motor generator control module. Either the drive motor generator battery control module or the drive motor generator control module can command that the HV contactors be opened in the event a system fault is detected. The contactors must be opened and closed under tightly controlled conditions in order to prevent damage to either the drive motor generator power inverter module or the HV contactors themselves.
In order to prevent damage to the drive motor generator power inverter module capacitors, the HV contactors are always closed in the following sequence:
1. The negative HV contactor is closed.
2. The current limit relay is closed. The precharge high voltage circuit contains an in-line current limit resistor. With both the negative HV contactors and the current limit relay closed, the positive HV contactor is slowly brought to operating voltage to prevent surge damage of the drive motor generator power inverter module capacitors.
3. Once the drive motor generator battery control module reads 90 percent of available buss voltage at the HV terminals, the drive motor generator battery control module will close the positive HV contactor.
4. The positive HV contactor is closed. The positive HV contactor bypasses the current limit relay and resistor in the precharge circuit and allows high current flow in and out of the hybrid batteries to occur.
5. The current limit relay is opened once the system is at operating voltage.
In order to prevent damage to the HV contactors, current flow through the contacts must be minimized prior to any attempt at opening them. The drive motor generator battery control module must ensure the system is in a low current flow condition prior to allowing the drive motor generator battery control module to open the HV contactors. The drive motor generator control module will command that all high voltage components like the accessory DC power control module and the air conditioning compressor stop drawing current. Also, the drive motor generator control module will ensure that the motor/generators have stopped rotating and that they are neither consuming nor generating electrical current.
The high voltage contactors are connected in series between the high voltage contactor terminals and the high voltage cables.
Output Circuits - The Drive Motor Battery Coolant Fan/Pump
The drive motor generator battery is cooled by the drive motor battery coolant fan, and the drive motor battery coolant pump. The drive motor battery coolant fan and the drive motor battery coolant pump are located inside the drive motor generator battery assembly and controlled by the drive motor generator battery control module. The drive motor generator battery control module monitors four hybrid battery temperature sensors, one air inlet temperature sensor, and a coolant temperature sensor, located in the radiator assembly. These temperature sensors are internal to the drive motor generator battery assembly. The four hybrid battery temperature sensors are located between the hybrid batteries. The resistances of these temperature sensors decrease as the temperature increases.
Drive Motor Generator Battery Venting System
The drive motor generator battery contains 22 individual battery modules. The hybrid batteries vent system connects all the battery vents to a rubber manifold that exits at the rear of the hybrid drive motor generator battery through a single hose and is vented through the load floor panel of the vehicle. These vents are mechanical and will only open when a predetermined amount of internal battery pressure is reached.
Drive Motor Generator Battery Control Module Power Limit Capability
The drive motor generator battery control module communicates the amount of power available from the drive motor generator battery for use by the hybrid system and also the amount of charge power allowed back to the drive motor generator battery from the hybrid system. This information is sent over the communications network to the drive motor generator control module.
The drive motor generator battery control module can adjust these power limits either based on hybrid battery temperature, hybrid battery voltage or DTC information.
The drive motor generator control module compares the drive motor generator battery control module power limit capability to a similar value calculated in the drive motor generator control module and uses the lower of the 2 values to control the power.