BATTERY MANAGEMENT SYSTEM

5/2015

The RIMAC AUTOMOBILI BATTERY MAN-

AGEMENT SYSTEM (R-BMS) is a full solution

for monitoring and controlling of complex battery

systems for various applications.

The latest R-BMS is our fifth generation system,

where we have implemented new functionalities

and all our experience gathered during the im-

plementation of high-power battery systems in

extremely demanding applications ranging

from electric supercars to boats, bicycles and

wheelchairs.

The system is primarily designed for electric ve-

hicles but is also used in various applications

such as hybrid vehicles, battery test-benches

and dyno systems.

The newest R-BMS generation features ex-

tremely compact dimensions, ultra-low

power consumption, very high measure-

ment accuracy and fast refresh rates.

R-BMSFUNCTIONALITIES

OVERVIEW

COMPLETE BATTERY MANAGEMENT SOLUTION

CELL MONITORING

TEMPERATURE MONITORING

ABILITY TO CONTROL SEVERAL EXTERNAL DEVICES

SYSTEMS FOR RETAINING MAXIMUM BATTERY LIFETIME

STATE OF HEALTH ESTIMATION

CELL BALANCING

STATE OF CHARGE ESTIMATION

THE R-BMS CONSISTS OF:

• BMS SLAVE UNIT(S)

• BMS MASTER UNIT

OVERVIEW

BMS SLAVE UNIT(S)

BATTERY PACK

POWER DISTRIBUTION UNIT

COMMUNICATION AND SIGNAL LINE

HIGH VOLTAGE

BMS MASTER UNIT

The R-BMS consists of one or more dis-

tributed R-BMS Slave devices, which

can monitor and balance a series from 3 up

to 12 battery cells.

Several R-BMS Slave devices can be used

in a battery pack or module, being able to

supervise a complete HV battery ranging

from 6V, up to 1000V.

R-BMS Slave devices have no power con-

sumption from the monitored cells while

the system is not active or the vehicle is

off. This feature ELIMINATES “VAMPIRE

LOADS” that are common with traditional

BMS systems, which can cause the bat-

tery to discharge completely and perma-

nently damage the cells. There is no need

to charge the battery in case the vehicle is

not being used for a longer period of time.

During the normal operation, power con-

sumption is less than 5mA per cell.

R-BMS SLAVE BMS SLAVE UNIT FUNCTIONAL OVERVIEW

CELLS

CELLTEMPERATURE

TEMPERATUREMEASUREMENT

PCBTEMPERATURE

BALANCING MODULE

CELLMEASUREMENT MICROCONTROLLER

ISOLATEDPART

COMMUNICATIONMODULE

INSULATION

BMS SLAVE SMART SLAVES

CAN OR FO

The R-BMS slaves are supervised by

the R-BMS Master unit.

The R-BMS system is capable of supervis-

ing all types of available battery chemis-

tries. Flexible hardware design allows the

system to measure single cell voltage in

a range from 0V to 5V with measurement

accuracy of 1mV. The measurement accu-

racy is consistent for the whole battery for

voltages up to 1000V. Furthermore, each

R-BMS slave measures 2 cell tempera-

tures and 2 PCB temperatures allowing it

to supervise the temperature throughout

the whole battery pack. Each R-BMS slave

device is equipped with passive resistive

balancing that can balance overcharged

cells with the current of 1A.

By using very precise measurements and

implementing smart balancing algorithms

the R-BMS has shortened needed bal-

ancing several times.

Collected R-BMS slave data is constantly

distributed through the high speed CAN

network with transmit period of 50ms, mak-

ing the data available on other devices 20

times per second. Due to the fast refresh

rate, it is possible to implement SMART

CONTROL ALGORITHMS which maxi-

mize cell usage while retaining maxi-

mum lifetime. In applications with the

high EMC noise, the R-BMS can be used

with the Fiber Optic communication in-

stead of CAN, making it entirely immune to

the EMC noise.

OPTIMISED BATTERY USAGE AND LIFETIME

R-BMS SLAVE

117 mm

102

mm

R-BMS SLAVESPECIFICATIONS

The R-BMS Master device is the central

unit supervising and controlling the

whole battery pack.

It is capable of calculating very accurate

State of Charge (SoC) and State of

Health (SoH) of the battery pack. Some

of the used cell chemistries have a very flat

voltage curve throughout most of the SoC

making it impossible to determine (or even

estimate) the SOC based on the cell-volt-

age alone. Therefore a very accurate SOC

calculation is needed, as well as a very ef-

fective balancing method.

In order to achieve a very high accuracy

of SOC and energy consumption estima-

tion, the R-BMS system uses a MORE

SOPHISTICATED METHOD than the

industry-standard single-current-sensor

set-up. Each high-voltage system can be

monitored individually through separate

energy measuring channels.

R-BMS MASTERBATTERY SUPERVISION AND CONTROL

CURRENT SENSORS CURRENT SENSORS

HIGH-SIDESWITCHES(6A)

HALF-BRIDGESWITCHES(4A)

MICROCONTROLLERDIGITALINPUTS

MASTER

The R-BMS Master system is capable

of controlling (supplying power to)

several external devices through the in-

telligent high-side drivers. All of those driv-

ers are equipped with several protections

and are capable of DETECTING AND

PREVENTING the overcurrent, overvolt-

age, overtemperature and reverse polarity

conditions. The high-side drivers are usu-

ally used to control several high-voltage

relays.

The R-BMS Master system can be used

either as a stand-alone unit or fully con-

trolled through different communica-

tion protocols. If configured to work as a

stand-alone unit, the R-BMS system can

control the pre-charge of several high-

voltage devices. It is also capable of

monitoring the status of each high-voltage

relay and able to detect the welded state

or the state in which the relay will not close.

The R-BMS system is equipped with sev-

eral CAN, Fiber Optic, RS232 and RS485

communication lines that can be used

to distribute the collected and calcu-

lated data. The R-BMS system is also

equipped with the bootloader capabil-

ity, making it possible to fully program and

configure any R-BMS device without the

need to directly access them.

R-BMS MASTER

CONTROL AND COMMUNICATION

291 mm

128

mm

R-BMS MASTERSPECIFICATIONS

R-BMS & INFOTAINMENTEASIER INTEGRATION FOR FASTER DEVELOPMENT

During the development and testing

phase of the project it is desirable to

show as much system data as possi-

ble on the vehicle In-Vehicle Infotainments

system.

With the R-BMS system this is easily done

as the system sends all cell-voltages, tem-

peratures and currents to the In-Vehicle

Infotainment which displays all data in real-

time. This gives the development engineers

a very good overview of the behavior of all

systems.

As most of those values are not relevant

to the end-user, once the development is

completed, only a summary of values such

as the SOC and battery-temperature is

available to the user.

RIMAC AUTOMOBILI

CONTACT:

MARKO PEJKOVICBusiness Development Manager

tel. +385 91 333 6162solutions@rimac-automobili.com