Skip to end of metadata
Go to start of metadata

You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 3 Next »

  • Ensures that the battery pack operates safely and reliably.

  • Prevents battery from operating outside of the safe operating area, calculate/reporting secondary data

  • Within the BMS, algorithms are run to generate accurate estimations of outputs, based on inputs

  • Redirects the recovered energy into battery pack

BMS Thermal

  • Colling is either passive (relies only on convection current of the surrounding air) or active (using fans), and liquid, air, or through phase change

  • Adds to weight of BMS, and air cooling require large amounts of power than liquid cooling

BMS Inputs (High Level)

  • cell/pack voltages

  • temperature sensors for cells

    • Get a sense of the temperature distribution of cells

  • current flowing into/out of battery pack)

    • Determine if charging/discharging and at what magnitude

BMS Outputs (High Level)

  • State of Charge (SOC)

    • Ex: battery percentage in phones/EVs

  • State of Health (SOH)

    • Current battery capacity compared to the beginning of life

    • Ex: SOH of a phone battery depletes over time

  • Safe Operating Envelope

    • Indicates how much current can be charged/discharged at any given time

  • Faults and Status Signal

    • May be required for other triggers

  • Maximum charge current limit (CCL)

  • Maximum discharge current limit (DCL)

Provides Protection Aganist:

  • Over-current, Over-voltage (charging), Under-voltage (discharging)

  • Over/Under temperature

  • Leakage

Means Of Protection

  • internal switch which is opened by BMS if battery operates unsafely

  • Request devices to limit or terminate battery usage

  • Actively control the environment (heaters, fans, liquid cooling)

State of Charge (SOC)

SOC - Capacity

SOC = (Capacity Remaining) ÷ (Total Capacity)

  • The voltage level of the pack will reach termination voltage as mAh is discharged (SOC also depletes)

  • Calculated using Coulomb Counting, where the charging/discharging current of the battery is measured and integrated over time to determine the SOC

(204) Part 3 Coulomb Counting Method for SoC Estimation of battery - YouTube

  • Inverse is Depth of Discharge (DOD)

    • EX: 70% SOC = 30% DOD

SOC - Energy

  • More accurate for fuel gauges in EV’s, as it indicates expected run time, usage, and distance remaining

  • In the graph, an SOC(E) of 50% is achieved when the area underneath the curves (amount of energy supplied) is equal on both sides, which occurs at around 42% SOC(C)

  • No labels