Battery Power - Spring 2015 - (Page 18)

Feature Battery Management with an Intelligent Battery Sensor is Vital to the Success of Future Automotive Designs Christopher Lohmeier, R&D Engineer Tom Veik, Sr. Engineering Technician Vishay Intertechnology Modern automobiles need to become more efficient to comply with future fuel economy standards. Much of this efficiency can be, and has been, gained with innovations that depend on the vehicle's electrical system. Technological innovations such as stopstart, drive-by-wire and brake-by-wire systems are just a few of these improvements. All of these new technologies, however, have one major downside in that they rely on the one component of the electrical system that has not seen much innovation since the 1950s: the lead-acid battery. Proper battery management will be the key to allowing innovation to continue in future designs, and it can be achieved with an intelligent battery sensor (IBS). An IBS unit gives precise and on-demand current, voltage and temperature (IVT) measurements from the battery. This information allows for accurate "state of charge" and "state of health" calculations to be performed, ensuring the electrical system works at the highest level of efficiency. IBS Overview An IBS is a total measurement system for lead-acid battery management. These components measure the charge or Figure 1. Intelligent Battery Sensor discharge current flowing through the battery, the voltage across the battery terminals, as well as the temperature of the battery through thermal conduction between the battery post and the IBS unit itself. All three of these measurements are taken almost simultaneously to ensure accurate measurements, even during times of rapidly changing conditions. An IBS can use a LIN communication protocol to send the results of these measurements to the vehicle's electronic control unit (ECU) or other control system. LIN is a robust protocol with a great noise tolerance for automotive environments. A LIN bus is already available on most new production models, or can easily be developed with simple microcontrollers when using the IBS in other automotive or non-automotive applications. IBS units should be built to handle the full range of automotive operating conditions. For example, a -40°C to 115°C temperature rating would allow the device to survive conditions that would damage even the newest, most advanced lead-acid batteries. In addition, a high voltage range lets the unit continue to retrieve data under both battery overcharge and undercharge conditions. The device should be able to monitor the full current band at both ends of the voltage and temperature extremes with minimal loss in accuracy. IBS Accuracy At the heart of an IBS is a shunt, which is specifically designed for sensing battery currents. The precision internal electronics of the IBS should be robust enough to handle the under-hood environment of modern vehicles and maintain accuracy when sensing the voltage drop across the shunt. The IBS and integrated electronics must handle all 12 V automotive starting currents, while limiting the error to a maximum of 0.5 percent (± 30 mA offset) over the entire measurement and battery temperature range. An additional benefit of an IBS, on top of the current sensing ability, is that the battery temperature sensor and voltage sensor are all contained within the one unit. So, for example, let's say that the 18 Battery Power * Spring 2015

Table of Contents for the Digital Edition of Battery Power - Spring 2015

Battery Power - Spring 2015
Batteries: An Integrated Solution
Preventing Counterfeiting: Challenges and Selection Criteria for An Ideal Authentication Solution
Extending Battery Life
Batter Management with an Intelligent Battery Sensor is Vital to The Success of Future Automotive Designs
ICs & Semiconductors
Testing & Monitoring
Conference Preview: Critical Power 2015
Research & Development
Industry News
Application Profile
Calendar of Events

Battery Power - Spring 2015