In people's daily life, the importance of batteries is becoming more and more prominent, mainly reflected in two major application areas: one is consumer electronics represented by mobile phones, laptops, TWS earphones, and smart watches; the other is new energy car. Especially for new energy vehicles represented by pure electric vehicles, due to the immaturity of the energy supplement system at this stage, it cannot keep up with the development of application requirements. Therefore, how to make better use of the existing electric energy in the battery and improve energy efficiency has become an and the focus of consumers' attention. At this time, the importance of the battery management system (BMS) is highlighted.
BMS plays a key role in people's daily life and industrial applications. Generally speaking, the system mainly serves the following functional requirements: by monitoring external parameters such as voltage, current, temperature, etc., real-time detection of battery status, and through The algorithm estimates the battery's resistance, maximum capacity and other parameters; improves the energy utilization rate of the battery and provides data support for the use and maintenance of the battery; avoids overcharging and overdischarging of a single battery cell; ensures user safety; prolongs battery life .
In BMS, the above functions are mainly realized by the battery management chip (BMIC). In order to realize these functions, the research and development of BMIC is a complex work across multiple disciplines. , Circuit reliability and other aspects have profound technical accumulation.
BMIC classification
BMIC is divided into two types: general-purpose and special-purpose. General-purpose chips include MCU, power management chip, communication interface and other chips. Special-purpose chips need to be specially developed for BMS applications to meet the functional requirements of specific applications.
BMS dedicated chips can be divided into battery protection chips, power metering chips, charging chips, battery monitoring chips, battery authentication chips, etc. The following briefly introduces these BMICs.
Battery protection chip
The battery protection chip is responsible for monitoring the charge and discharge of the battery cells to ensure that the battery will not be damaged due to external misuse or failure. When an abnormal situation is detected in the system, the safety chip can cut off the circuit in time to ensure the safety of the battery system. At present, some BMICs (charging chips, fuel gauges, etc.) will integrate protection functions, but in order to achieve more comprehensive protection, a dedicated battery protection chip is still an indispensable component in many applications.
Power meter chip
The role of the power metering chip is to measure the external characteristics of the battery (such as voltage, current, temperature, etc.), use a specific algorithm to estimate the SOC/SOH parameters of the battery, and feed back the results to the control chip.
Charging chip
The charging chip mainly implements two functions of power path management (PPM) and charge and discharge control. Power path management is to control the power path so that the switch of the external power supply does not affect the normal operation of the system; charge and discharge control is to properly control and manage the charge and discharge of the battery. Typical battery charging processes are usually divided into trickle current, constant current and constant voltage stage, the switching control between each stage is completed by the charging chip.
Limited by cost, volume and heat dissipation requirements, charging chips are generally only used for charging low-power electrical appliances. For high-power applications (such as electric vehicles), dedicated high-power charging circuits composed of discrete devices are generally used.
Battery monitoring chip
The main function of the battery monitoring chip is to monitor battery parameters with high precision and send relevant data to the main control chip through the communication interface. Different from the power monitoring chip, the battery monitoring chip only has the function of parameter monitoring, and is generally used in the occasion of high string number series connection (10 strings to hundreds of strings). At this time, multiple monitoring chips need to be cascaded to form a monitoring system.
Battery Authentication Chip
In order to prevent unmatched batteries from causing damage to equipment or users, a battery authentication chip will be integrated in the battery pack and authenticated when the battery is connected to the system. Only batteries that pass the authentication can supply power to the system. Although the batteries of many systems are not removable, in order to avoid potential risks caused by users replacing batteries by themselves, manufacturers generally configure an authentication chip in the built-in battery of the device.
Electric vehicle BMIC development speeds up
In 2021, the global lithium battery BMIC market size is about 4.254 billion US dollars, and it is expected to increase to 8.031 billion US dollars by 2026, with a compound annual growth rate (CAGR) of 13.55%. Among them, the fastest growing markets are energy storage, automobiles and consumer (mobile phones, laptops, tablets, TWS earphones, smart watches, etc.) markets, with CAGRs of 72.34%, 40.07%, and 14.50% in 2021-2026, respectively. . It can be seen that in people's daily life applications, the growth rate of BMICs for automobiles, especially electric vehicles, is very impressive, far exceeding the consumer electronics market.
