Monitoring & Switching Power in Automobiles

October 27, 2016 // By Pinkesh Sachdev, Linear Technology
The discrepancy between driving range and the availability of charging stations makes exact monitoring of the available battery capacity a necessity. This article details the circuitry necessary.

It’s easy to appreciate the benefits of the electronics that power the many functions in a modern vehicle, from our heated seats, air conditioning, navigation, infotainment and safety systems designed to increase comfort and our overall driving experience. It’s hard to imagine what it must have been like just over 100 years ago when there was not a single electrical component in gasoline-powered automobiles. Turn of the century automobiles were started with hand cranks, headlights were lit with acetylene gas and pedestrians were alerted with a ringing bell. Now, the modern motorcar is at the cusp of transforming into an electrical system with as few mechanical systems as possible, becoming the biggest and most expensive “digital gadget” in a person’s life. This transformation is driven by the market pull to be less reliant on oil, for availability and environmental reasons, as well as to increase safety in combustion, hybrid and all-electric vehicles.

As more mechanical systems are replaced by an electronic equivalent, power consumption and ways to monitor it become increasingly important. Accurately monitoring power consumption in an electric vehicle ultimately provides additional peace of mind to the driver. Anyone who has had the opportunity to drive a fully electric vehicle will probably have experienced range anxiety, the ever-present threat that the car battery will run out of power before reaching the destination. Hybrid vehicle owners have the luxury of the gas-powered engine to get them home but electric vehicles are only recharged at charging stations, which today are few and far between, and take hours to recharge the battery. Therefore, it is important to monitor the power consumption of each electronic sub-system continuously and accurately. This information can also be used to advise the driver on ways to preserve battery life and extend driving range. Further power savings are afforded by disconnecting idle modules from the power bus. Monitoring sub-system current and power levels may also reveal any abnormal

Design category: