Issue link: https://resources.mouser.com/i/1442820
| 11 | Component Solutions to Help Meet Automotive CO 2 Emissions Reduction Using High Power Inductors and Current Sense Resistors for Micro Hybrid Vehicle DC/DC Converters By Bourns, Inc. Introduction In the drive to reduce CO 2 emissions, automotive companies are deploying innovative methods to meet these environmental demands. A promising vehicle type in this area is the micro hybrid, which uses a stop-start system and regenerative braking to help achieve the desired reduction in CO 2 emissions. For micro hybrid applications, a 48V starting motor can restart the engine quicker than a 12V starter. That is why many micro hybrid vehicles use a combined 48V starter / generator. This requires a DC/DC converter to efficiently change alternator output voltage from 48V to 12V in order to charge the battery. A DC/DC converter is also needed to convert the battery voltage from 12V to 48V in order to drive the starter motor. High powered inductors and current sense resistors that can provide the very low DC resistance (Rdc) characteristics needed for power conversion and supply requirements are important for efficient DC/DC converter designs in automotive applications. This application note will illustrate a micro hybrid design that uses Bourns ® Model PQ series high power inductors that are designed to handle high current levels in a compact form factor, making them ideally suited for these types of applications. Also included is an optimal solution for sensing current measurement with Bourns ® Model CSS2H series current sense resistors. Stop-Start System Basics A regenerative braking system only charges the battery when the vehicle is free-wheeling, braking, or decelerating. During acceleration the alternator is decoupled from the drivetrain, contributing to improved fuel economy and enhanced acceleration as all of the engine's power is driving the wheels. Conventional alternators charge the battery whenever the engine is running.