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BMS: Battery Management System

The BMS evaluates the measurement around the battery system and combines it with user requests to operate the battery.

component component dialog parameters
property tabs
  1. General
  2. Current Limit
  3. limits

Block Diagram

The BMS is internally a C-function that evaluates inputs from the user (e.g. set points) and measurements (voltage, current, temperature) of the battery system. Limits are defined in the mask and cover the follwing questions:

  • Current limit contains a soc dependent maximum current that is most relevant for DC fast charging and is special for every EV, see also ev twin.
  • Battery voltage limits (min and max)
  • Battery temperature operation range

The resulting states are used to control the contactors in Power Unit. For details see section Inputs and Outputs.

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Modes and States are predefined via constants:

POWER_MODE_ERROR = -1
POWER_MODE_OFF = 0
POWER_MODE_AC = 1
POWER_MODE_DC = 2
POWER_MODE_DRIVING = 3

#Mode Battery
BATTERY_MODE_ERROR = -1
BATTERY_MODE_DISABLE = 0
BATTERY_MODE_ENABLE = 1
BATTERY_MODE_VENT = 2

#BMS STATUS
BMS_STATE_ERROR_TEMPERATURE = -4
BMS_STATE_ERROR_VOLTAGE = -3
BMS_STATE_ERROR_CURRENT = -2
BMS_STATE_ERROR = -1
BMS_STATE_OFF = 0
BMS_STATE_AC_CHARGE = 10
BMS_STATE_AC_CHARGE_LIMITED = 11
BMS_STATE_DC_CHARGE = 20
BMS_STATE_DRIVING = 30

AUTO_RESET = 1

Inputs and Outputs

Input

Number Input Description range default
1 mode bat Battery mode, enabling battery 0
2 mode power Power mode: AC, DC, Driving, ...
3 reset Reset of BMS
4 conditioning enabling battery conditioning True, False False
5 Ibat battery current
6 voltage battery voltage
7 soc battery state of charge
8 temperature battery temperature

Output

Number Output Description range default
1 cont list of states for the contactors [AC, DC, driving]
2 condition voctor [enabling conditioning, current conditioning]
3 bat_status status of battery
4 BMS_STATE status message of BMS
5 Ilim current limit for current
6 lmits vector of other limits [ Vbat min, Vbat max, T min, T max]

Dialogue box and Parameters

The BMS subsystem is organized in three tabs.

Tab 1 - General

Parameter Code Name Description

Tab 2 - Current limit

Parameter Code Name Description

Tab 3 - limits

Parameter Code Name Description