The ultimate challenge for researchers today is to enable the seamless migration of society into the post-oil age. Running out of affordable fossil fuel for the mobile society might come faster than expected, and full focus should be put on developing valuable replacement solutions with short-term perspective over ambitious long-term research projects.
For example, to name just two such long-term research segments, there is nuclear hydrogen fusion for a terrestrial energy source, and hydrogen as an alternative over carbon hydrogen (i.e., hydrocarbons, such as methane, butane, etc.).
From a semiconductor point of view—with a focus toward automotive ICs (integrated circuits), this challenge can be addressed by carefully looking at available technologies and developing component-level short-term solutions for the highly dynamic e-vehicle industry. Energy storage in batteries seems to be a predictable key technology for both mobile and stationary applications since it provides a decentralized renewable energy source. It is therefore important to focus on mobile battery management solutions.
Due to the diversity of battery technologies and applications, semiconductor manufacturers must be able to support such developments in a flexible way to quickly reach affordable and reliable solutions. A good strategy is to develop IC solutions with smart architectures that are not overly integrated, which allows designers a high degree of flexibility.
Today there are two main fields in automotive battery technologies.
First, there is the conventional 12-V lead-acid battery system used in internal-combustion-engine cars. Although this was thought to be an established and mature technology for many years, new fuel-saving technologies like auto idle stop, brake energy recovery/micro hybrid/efficient dynamics are posing new challenges due to the changes in load and charge profiles.
There are new solutions like dual-battery architectures connected through a bi-directional dc/dc converter for two different voltage and power domains. Then there are new battery designs in development using methods to avoid acid stratification. Also in discussion is cell balancing in cell chains or switching to lightweight lithium-ion (Li-ion) batteries or in combination with ultracapacitors.
As a consequence, IC solutions must safely support current, voltage, and temperature sensing for numerous conditions including: various voltage domains at pack level; for high- and low-side supply rails; cell balancing and monitoring at the cell level, and do this for various battery chemistries and technologies. Flexible IC solutions are needed to cover battery parameter sensing at high accuracy at pack—and at cell level at a moderate integration level to address the challenges to come.
The other field of application is traction batteries for full electric- or hybrid-electric vehicles. There are many battery technologies in development starting with nickel/metal hydride through various types of Li-ion chemistries eventually combined with ultracapacitors. The IC sensing & measurement solutions are faced with difficult challenges and must accurately and reliably communicate all relevant data.
To address such system design challenges, the first prototypes of a unique cell balancing/monitoring IC have been developed by austriamicrosystems to address the challenges known today. The IC offers simultaneous cell voltage capture for autonomous balancing at a low current level as a background operation in either a highly efficient active way through one small dc/dc converter for up to 14 cells, or for passive balancing through one flying discharge resistor per seven cells. The device works with virtually no external components. For small battery management solutions—up to seven cells as used for e-bikes—the device could perform the balancing job without a microcontroller.
This article was written for Automotive Engineering’s 100th anniversary by Bernd Gessner, Senior Vice President, austriamicrosystems AG, Automotive BU General Manager.