BMS (Battery Management System) battery management system is a management system for lithium batteries of electric vehicles, which is the key link between the "battery", the core component of electric vehicles, and the entire vehicle. BMS is an accurate "tuner" for electric vehicle batteries. Generally speaking, BMS can help solve safety issues such as increasing inconsistencies between batteries, battery efficiency, poor life, and serious fires. As people's pursuit of new energy vehicle endurance and battery safety continues to grow, the battery management system BMS is increasingly valued.

Generally speaking, the BMS is composed of a master control unit and multiple slave control units. The slave control unit is directly connected to the battery pack (Battery Pack) to collect battery voltage, current and temperature. (Chrysanthemum chain) Manage multiple slave control units through communication and other methods. The NMS S32K144-based BMS all-in-one solution launched by the General Assembly World Peace Group supports daisy chains and CAN networks. It has great flexibility and can meet the needs of different customers.

Hardware design

Control section

Use NXP S32K144 as the control and processing unit of BMS. On the one hand, CAN BUS can be connected to other BMUs and other ECUs to receive signals from many sensors on the body. Layer (TPL) communicates with NXP MC33771 AFE IC to obtain the data collected by AFE. The features of S32K144 are as follows:

ARM Cortex-M4 up to 112Mhz;

Flash / RAM-512 KB / 64KB;

Rich peripheral resources: 4 × 16bit timer, 1 × 32bit LP timer, RTC, 4 x LPSPI (with 1 emulated SPI by Flex IO), 4 x LPUART, 3 x FlexCAN, 2 x16 (12-bit) ADC

Function Safety ASIL-B

The S32K series has a variety of products for customers to choose from, and has a wealth of supporting tools for customers to develop

AFE battery cell control IC

The MC33771 is designed for automotive applications such as SMARTMOS lithium-ion battery controller IC hybrid (HEV) and electric vehicles (EV) and industrial applications such as energy storage systems (ESS) and uninterruptible power supplies (UPS) systems.

Capture the battery voltage and current through ADC conversion and include coulomb counting and temperature measurement. Through the Serial Peripheral Interface (SPI) or Transformer Isolation (TPL) to the microcontroller for processing.

6 V ≤ VPWR ≤ 61.6 V operation, transient voltage 75 V

7 ~ 14 cell measurement

0 Mbps TPL or 4.0 Mbps SPI transmission mode

Maximum total voltage measurement error is 8 mV

Maximum support 300 mA passive battery balancing and diagnosis

Designed to support ISO 26262, the highest ASIL D safety capability

Complies with AECQ-100 standard

Debug interface screenshot

Feature demo photos

Scene application diagram

Display board photos

Core technical advantages

① Monitor the voltage and temperature of single battery

② Monitor the voltage, current and temperature of the entire string

③ Passive equalization function between single cells

④ Use CAN bus or daisy wheel connection between battery packs

⑤ With multiple protection and diagnosis functions

⑥ Support two optional communication methods of SPI / TPL

Scheme specifications

① A single MC33771 can monitor 7 to 14 strings of batteries

② Built-in passive balancing current switch tube, maximum support 300 mA passive balancing current

③ Built-in coulomb counter for current detection

④ ASIL C chip functional safety level

⑤ Can support 63 MC33771 cascade

⑥ Detection accuracy 2 mV

⑦ Support 43 internal self-test functions

⑧ Simultaneous measurement of voltage and current within 65 us

Key Components