Battery management system
BMS
means
different
things
to
different
people.
To
some
it
is
simply
Battery
Monitoring, keeping a check on the key operational parameters during charging and
discharging
such
as
voltages
and
currents
and
the
battery
internal
and
ambient
temperature.
The
monitoring
circuits
would
normally
provide
inputs
to
protection
devices
which
would
generate
alarms
or
disconnect
the
battery
from
the
load
or
charger should any of the parameters become out of limits.
For the power or plant engineer responsible for standby power who's battery is
the
last
line
of
defence
against
a
power
blackout
or
a
telecommunications
network
outage BMS means Battery Management Systems. Such systems encompass not only
the monitoring and protection of the battery but also methods for keeping it ready to
deliver full power when called upon and methods for prolonging its life. This includes
everything from controlling the charging regime to planned maintenance.
For the automotive engineer the Battery Management System is a component of
a
much
more
complex
fast
acting
Energy
Management
System
and
must
interface
with
other
on
board
systems
such
as
engine
management,
climate
controls,
communications and safety systems.
There are thus many varieties of BMS.
Designing a BMS
In order to control battery performance and safety it is necessary to understand
what needs to be controlled and why it needs controlling. This requires an in depth
understanding
of
the
fundamental
cell
chemistries,
performance
characteristics
and
battery failure modes particularly Lithium battery failures. The battery can not simply
be treated as a black box.
BMS Building Blocks
There are three main objectives common to all Battery Management Systems
•
Protect the cells or the battery from damage
•
Prolong the life of the battery
•
Maintain the battery in a state in which it can fulfil the functional requirements
of the application for which it was specified.
To
achieve
these
objectives
the
BMS
may
incorporate
one
or
more
of
the
following functions. (Follow the links to see how these functions are implemented.)
•
Cell Protection