DC To DC Converter Control Module (DC/DC)

High-Voltage Converter/Inverter

Principles of Operation - DC to DC Converter Control Module (DC/DC)

The DC to DC Converter Control Module (DC/DC) is a liquid-cooled component that converts high voltage (179-343 volts) DC power to low voltage (12 volts) DC power, while maintaining electrical isolation between the 2 systems. The DC/DC is enabled when the High Voltage Traction Battery (HVTB) contactors have closed, providing high-voltage power to the DC/DC (for information on the HVTB system, refer to High Voltage Traction Battery Testing and Inspection). The DC/DC steps the high voltage down to a low-voltage (between 12 and 15 volts, depending on vehicle needs), providing power to the vehicle low-voltage battery systems. The DC/DC also charges the 12-volt battery through the low-voltage battery cables as necessary, eliminating the need for a conventional engine-driven generator. Depending on vehicle and environmental conditions, the DC/DC is capable of outputting as many as 145 amps to the 12-volt battery.

The DC/DC is liquid-cooled and is part of the Motor Electronics Cooling System (MECS). In addition to the DC/DC, the MECS also provides cooling of the Electronically Controlled Continuously Variable Transmission (eCVT). For information on the MECS, refer to Transaxle/Transmission Cooling - Hybrid Testing and Inspection.

The DC/DC communicates on the High Speed Controller Area Network (HS-CAN). When a fault is sensed by the DC/DC, a DTC is set and can be retrieved using a scan tool connected to the Data Link Connector (DLC). The PCM communicates charging needs of the 12-volt system to the DC/DC over the HS-CAN, enabling the DC/DC to control low-voltage charging operations.

The DC/DC receives the following HS-CAN messages:

- Transmission Control Module (TCM) high-voltage input, via the TCM
- Ignition status, via the Instrument Panel Cluster (IPC)
- MECS coolant temperature, via the PCM
- "Ready Indicator Light" illumination request, via the PCM
- Transaxle gear mode, via the PCM
- DC/DC enable and low-voltage set point request, via the PCM

Faults with the DC/DC system that cause low or excessively high 12-volt battery voltage will result in the DC/DC sending a HS-CAN message to the IPC requesting the CHECK CHARGING SYSTEM message be displayed in the message center.