Simulink is a great environment when it comes to developing such algorithms. Before running the BMS Algorithm on real hardware with real Lithium cells, the algorithm can be designed and validated using Simulink. To have a look at this kind of model, please visit the Battery Management System that Mathworks provides for free alongside videos and webinars explaining the model.
MBDT Battery Management System Library
The Battery Management System Library is fully integrated into the MBDT for S32K1xx. Once installed, the BMS blocks can be accessed under the External Devices Library.
With these blocks, NXP offers access to all the NXP’s Cell controllers features in Simulink environment. For example, this performs important measurements for a cell (voltage, temperature) as easy as adding a Simulink block from the library into the model.
The Library offers blocks for BCC Configuration, registers read/write and balancing. Basically all the data acquisition is performed by the NXP BCC blocks. The user can focus exclusively on the BMS Algorithm, Instead of dedicating time for reading the Battery Cell controller Reference Manual and writing the C code for data acquisition.
All the generated code is based on the Embedded SW: Battery Cell Controller Software Driver for MC33771B/MC33772B
MC3377xB Hardware
MC3377xB is an NXP Li-Ion battery cell controller family of ICs designed for automotive and industrial applications such as HEV, EV, ESS, UPS systems.
The boards main features are:
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ADC conversions on the differential cell voltages and currents as well as coulomb counting and temperature measurements.
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Embedded balancing transistors and diagnostics to simplify applications with Onboard 300mA Low Rdson passive cell balancing MOSFETs with diagnostics.
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Support standard SPI and transformer isolated daisy chain communication (with MC33664) to an MCU for processing and control.
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Up to 7 GPIOS that allows adding up to 7 NTC thermistors for temperature measurements.
The MC3377xB has 4 different derivatives. I will try to explain how to identify the best suitable one for your application related to the number of cells required:
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Small Battery Packs – up to 14 Cell Battery packs
For this kind of application, the MC3377xBSPI is suitable for the project. This chip connects to the main MCU over the SPI protocol. The MC33771BSPI can handle 7 up to 14 cells, while the MC33772BSPI can handle 3 up to 6 cells.
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Larger Battery Packs
This kind of application requires dividing the whole pack in smaller modules, only for measurement. For each module we need to connect one cell controller the MC3377xBTPL. Same, the MC33771BTPL can handle 7 up to 14 cells, while the MC33772BTPL can handle 3 up to 6 cells. All the cell controllers need to be connected in a daisy chain topology. Now, to connect the MCU in the same network, the MC33664 transceiver needs to be used. This is a transceiver physical layer transformer driver designed to conveniently interface a microcontroller to a high-speed isolated communication network. MCU SPI data bits are directly converted to pulse bit information and transferred to the bus network.
Full Datasheet and more documentation are available on docstore.nxp.com (NDA required).
Follow up on the next articles to understand all of the controllers mentioned above in your Simulink projects.
