BMS—"Physical Examination" and "Security Guard"
Regarding the function of BMS, the classification method is different in
the industry. However, from the user's point of view, it can be roughly divided
into two major functions-"physical examination" and "security guard".
"Physical examination" refers to the accurate grasp of battery status and
status assessment.
This "physical examination" is online, continuous, and uninterrupted. In
the process, when data is found to be abnormal, the corresponding battery status
can be inquired in time, and the problematic battery can be selected, so as to
maintain the reliability and efficiency of the entire battery pack.
After the "physical examination" is over, it will enter the stage of
analysis, diagnosis, and calculation, and then a "physical examination report"
will be generated. This process can be understood as the battery status
assessment.
At this time, we need to understand the common terms-SOC & SOH &
SOP.
State of Charge, or SOC, or remaining battery power. SOC is the basis for
judging a series of faults such as battery overcharge and over-discharge.
Accurate estimation of SOC can prevent battery overcharge and over-discharge,
extend battery life, and improve battery utilization.
SOH (State of Health), SOP (State of Power), the user can see these data
through the on-board instrument display to confirm the working and functional
status of the battery. Accordingly, on the basis of protecting the battery, the
potential will be maximized and the driving experience will be greatly
improved.
Therefore, the accuracy of SOC and other data estimates is particularly
important. The consequences of inaccurate estimation may be that the car breaks
down, does not match the expected mileage, etc.
For example, a vehicle with a cruising range of 400 kilometers is driving
on the road when it is fully charged. If the estimation is accurate, when the
SOC is displayed as 10%, the possible mileage is 40 kilometers; if the
estimation is not accurate and the SOC reaches 15%, the user thinks the mileage
is 60 kilometers. In fact, it may be after driving 40 kilometers. The battery is
dead. Obviously, this situation is very bad for users.
Another core function of BMS, "Safety Guard", can be simply understood as
the role of protection, which is mainly reflected in the protection of batteries
and high voltage safety.
Due to the complexity of the internal structure of the battery, abuse or
damage will affect the battery life and safety, and in severe cases, it will
cause the battery to run out of thermal control and cause a safety accident. The
BMS monitors the battery's protection function in real time, communicates with
external systems such as the vehicle and charger, and controls the charging and
discharging process in a timely and effective manner to prevent dangerous
accidents.
Secondly, the battery system voltage can reach 300-500V, far exceeding the
safety voltage of the human body, and there are high risks and hidden dangers,
and high-voltage safety protection is escorted for this. BMS detects and
controls possible high-voltage leakage risks by detecting insulation resistance,
high-voltage interlocks and relay status, thereby protecting the personal safety
of drivers, passengers and maintenance personnel.
The industry believes that installing an excellent BMS can effectively
improve the utilization of the battery, prevent the battery from overcharging
and over-discharging, and prolong the service life of the battery, monitor the
battery pack and the operating status of each battery in time, and effectively
prevent the battery pack from spontaneous combustion, such as Early warning is
given in case of emergencies to gain time for safety.
Lithium-ion battery (LIB) has become the main energy storage solution in
modern social life. Among them, lithium iron phosphate batteries are a perfect
replacement for lead-acid batteries, and they are the first choice for
grid-connected peak shaving, off-grid energy storage, photovoltaic energy
storage, UPS, data center and other industries.
