Ford Fusion: Voltage Converter/Inverter / Direct Current/Direct Current (DC/DC) Converter Control Module - Overview. Description and Operation

OVERVIEW

The Direct Current/Direct Current (DC/DC) converter control module also known as the Voltage Quality Module (VQM) is used on vehicles equipped with a start/stop system.

Stop-Start technology provides fuel savings by turning the engine off during stop events and then automatically re-starting the engine when the driver is ready to continue driving. Stop-start events, also called idle-stop events, begins when the driver presses their foot on the brake pedal, the vehicle speed is zero and the engine automatically shuts off. The stop start event continues as the driver maintains pressing of the brake pedal (e.g. for the duration of a traffic light). Once the driver releases the brake pedal, the engine automatically re-starts. The end of the stop start event occurs after the engine has re-started.

During these stop-start events, voltage variations will occur resulting from changes in electrical system loads. The Direct Current/Direct Current (DC/DC) converter control module function is to boost the voltage level for a select few components during an Autostart event. Once the starter engages, it draws a large amount of current and the entire vehicle voltage drops. There are some components that cannot experience that large voltage drop (e.g. audio system, instrument cluster, etc). The Voltage Quality Module (VQM) keeps the voltage boosted to those components for the short time while the starter is cranking to prevent the components from resetting or shutting down.