ams AG (SIX: AMS), a leading provider of high performance analog ICs and
sensors, today introduced a vastly simplified and more robust method of
implementing cell monitoring and balancing in lithium battery systems.
The innovative architecture developed by ams has been implemented in a
new, highly integrated chip, the AS8506, to perform distributed cell
monitoring and balancing operations for stacked cell modules, including
Safe Operating Area (SOA) checks and passive or active cell balancing.
It is ideal for all lithium-based cell chemistries, such as those found
in hybrid and fully electric vehicles, as well as for EDLCs (also known
as supercaps or ultracaps).
In conventional systems, a complicated algorithm running remotely on a
high-end microcontroller decides which cells have to be balanced. The
new architecture supported by the AS8506 can control balancing locally
at the cells, enabling designers to implement a more streamlined cell
management system that eliminates the powerful host controller, complex
software and vulnerable serial communication links normally used today.
The AS8506 can implement both passive and active cell balancing
autonomously, or it can support a microcontroller-based system via its
Serial Peripheral Interface. An advanced analog circuit in the AS8506
compares up to seven cell voltages against an internal or external
reference with an accuracy of 1mV, to support cell-balancing and
cell-monitoring functions. Cell voltage measurements can also be
digitized with an accuracy of 5mV and reported to a host controller.
Active and passive cell balancing use a similar circuit design, but
active balancing requires an additional flyback transformer. The control
circuit is integrated in the AS8506.
The device also features internally or external adjustable upper and
lower cell voltage limits. Temperature measurement is carried out
through two external NTC sensors.
The fully autonomous cell management architecture enabled by the AS8506
is in stark contrast to the typical system implementations found today
using existing cell monitoring ICs. These are typically limited to the
sequential capturing of cell voltage measurements that must be processed
by a host controller. These prior architectures have several drawbacks
for designers of battery management systems:
-
The system must stream large amounts of data over a serial link – a
communications channel that is vulnerable to interference in noisy
environments.
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A powerful host controller running complex software is required to
turn individual cell voltage measurements into useful functions such
cell balancing decisions. Writing this software is a difficult and
time-consuming task. The software requires exhaustive testing in order
to qualify for use in automotive ISO26262-compliant systems.
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Sequential cell measurements require complex compensation algorithms
in order to produce valid voltage and current readings across a stack
of cells. By contrast, the simultaneous measurements captured by the
AS8506 require no compensation.
“The AS8506 marks a breakthrough in cell monitoring – not an incremental
improvement on previous cell monitoring ICs, but a completely new
approach”, said Manfred Brandl, Product Manager for battery management
in the automotive business unit at ams. “By offering local cell and
temperature monitoring, the AS8506 gives system designers a simple and
robust means to implement a battery management system, with just a
simple microcontroller required for basic system functions.”
ams is demonstrating the AS8506 at Stand 74 at the VDI Congress on
‘Elektronik im Kraftfahrzeug’ (Baden-Baden, Germany, 16-17 October 2013).
Price & Availability
The AS8506 cell monitoring IC is available for sampling now. It is
priced at $9.10 for 1,000 pieces.
ams also provides a non-automotive version called the AS8506C. It is
priced at $7.80 for 1,000 pieces.
Technical Support
A stand-alone Cell Balancer Evaluation Kit for the AS8506 is available
online from ams, priced at $80. An Active/Passive Balancer Board is also
available at the ams online webshop, priced at $100. For further
information on the AS8506 or to request samples, please visit www.ams.com/cell-balancing-IC/AS8506
Download Press Picture or Block Diagram of this IC at
http://www.ams.com/eng/Press/Press-Releases/AS8506
Copyright Business Wire 2013