Battery Management Solution -...
Transcript of Battery Management Solution -...
Proprietary – For Big-bit New Energy Seminar Use Only
Battery Management Solution
Big-bit New Energy Seminar
For Big-bit Seminar Use Only
Who needs a BMS
l Cell lifetime is highAny Lithium battery technology
l Cell voltage outside its operation range (i.e. 2.5-4.2V) kills the cell and
can creates a fire hazard.
l Cell Lifetime is highly dependent on cell SOC control at all times
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What are the transportation market for BMS
Application Bus Voltage Power Battery Series
Electric Bicycle 36V to 48V 250W-500W 8-12S
Scooter 48V 1-10kW 12S
Motorcycle 60V 1-10kW 12-20S
48Vnet ICE mild HEV 48V 16kW 12-14S
HEV 120V-450V 10-150kW 20-100S
EV 270V-800V 20-300kW 65-200S
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Why MPS chooses 16 cells / BMS IC
On most Lithium technologiesto center the SOC around 48Vfor long life time the optimum is between 13 and 14 cells.
The “industry standard” 12 cellis just 1 or 2 cells short of the optimum.
To have 2 or 3 cell inputs reserve for alternative cell technologies is a very small overhead, since the additional circuitry (larger mux, pins, balance switch) is a small fraction.
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Battery Lifetime
For the user the battery reaches its EOL if the capacity of the weakest cell is to low to be usable.
Or if imbalance yield the same effect with one cell at the high side of SOC and another on the low side.
For this reason Lithium cells need to be balanced.
Imbalance result from cell temperature differences, different self discharge rates and different cell loading i.e. through monitoring electronics like the BMS.
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Battery Lifetime
For the user the battery reaches its EOL if the capacity of the weakest cell is to low to be usable.
Or if imbalance yield the same effect with one cell at the high side of SOC and another on the low side.
For this reason Lithium cells need to be balanced.
Imbalance result from cell temperature differences, different self discharge rates and different cell loading i.e. through monitoring electronics like the BMS.
For Big-bit Seminar Use Only
MPQ2645 Family Key Features
l Up to 80V Sustainable voltagel Up to 16-celll 16Bit SAR ADCl Integrated Balance Switchesl Up to 5GPIOs for Ext. Temp Monitorsl Stackable Differential BMS-LinkTM
l Compatible with both Daisy-chain and Multi-drop Connection
l Independent UV/OV Comparator for Each Cell
l Self-Diagnosisl Support Open-wire Detectionl AEC-Q100 Qualified
• Device Temperature Grade 2: -40ºC to 125ºC ambient Operating Temperature Range
• Device HBM ESD Classification Level 2• Device CDM ESD Classification Level
C3l Engineered for ISO26262 ASIL C
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MPQ2645 Family Derivatives
Derivatives MPQ2645A-AEC1
MPQ2645B-AEC1
MPQ2645C-AEC1
Daisy-chain
Multi-drop
I2C/SPI BMS-LinkTM I2C SPI
Cell Count 16 16 16
Package QFN64 10x10 QFN64 10x10 QFN64 10x10
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Typical Application CircuitDaisy-chain Differential signals
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Typical Application CircuitMulti-drop (I2C)
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Typical Application CircuitMulti-drop (SPI)
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Safety Analysis Methods Introduction
l HARA (Hazard Analysis and Risk Assessment)l FTA (Fault Tree Analysis)l FMEA (Failure Mode and Effect Analysis)l FMEDA (Failure Mode Effects and Diagnostic Analysis)l DFA (Dependant Failure Analysis)l DRBFM (Design Review Based on Failure Modes)
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Steps for FMEDA
Safety Goal
Identify the relevant modules
Determine failure rate and mode
Analysis of failure effects
Collection and assignment of
safety mechanism
Sorting the failure classes
Review the diagnostic coverage of each
safety mechanism
Output your FEMDA report and review it
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Functional Safety Focused
Built-In Self Tests
Separate Hardware Protection
Flexible Communication Architectures