With the popularity of electric vehicles, the automotive industry has attracted more and more attention from the market, and many manufacturers have shifted their focus to automotive-grade products. Microcontroller and Power Management IC, which are indispensable in the automotive industry, have attracted much attention in the past two years and have experienced a shortage of supply.
In order to promote the electrification of vehicles, improving battery life, charging speed and operating safety has become one of the key concerns of manufacturers. One of the keys involved is the battery management system (BMS). Battery management system chips play a important role in the new energy vehicle industry.
According to estimation by Persistence Market Research, the battery management ICs market is expected to grow steadily from 2022 to 2023, at a CAGR of about 5.1%. It is anticipated that demand for BMS ICs would increase due to the surge in interest in hybrid electric vehicles.
Leading manufacturers in the field of BMS include Texas Instruments, NXP, and others. TI launched the high-precision battery cell monitor BQ79718-Q1 at the new product launch conference of the high-voltage battery management system, which can realize very high-precision voltage measurement monitor products, and can well predict the real cruising range of electric vehicles. Wang Shibin, general manager of its battery management system division, said that through continuous innovation in BMS, TI battery ICs can help automakers improve design efficiency and the safety performance of the entire battery system, so as to better realize the popularization of electric vehicles.
The core technologies of electric vehicles include batteries, motors, and electronic control technologies. Among them, BMS (Battery Management System) is the core function of electronic control. BMS is a system for monitoring and managing batteries. It collects, calculates, and controls the charging and discharging process of the battery through parameters such as voltage, current, temperature, and SOC (State of charge), so as to protect the safety of electric vehicle power batteries and improve battery comprehensiveness. The performance management system is an important link connecting the vehicle power battery and electric vehicles.
The application fields of batteries are very wide. Consumer electronics in daily life such as mobile phones, laptops, earphones, smart watches, etc. In the automotive industry, especially new energy vehicles represented by pure electric vehicles, as well as in industrial applications, play a key role.
Battery Management IC (BMIC)
The hardware architecture of the battery management system includes the main board, slave board, BDU, and high-voltage control board. The slave board monitors the voltage, temperature and other information of the module, and transmits the sampled information to the main board. The main board communicates with the vehicle through the low-voltage electrical interface, controls the action of the relay in the BDU, and monitors the status of the battery. The high-voltage control board can be integrated on the main board, or it can be independent. It monitors the voltage and current of the battery pack in real time. It also includes pre-charge detection and insulation detection functions.
The chips mainly used in BMS are AFE, MCU, ADC, digital isolator, etc. AFE (Active Front End) is an analog front-end chip used in BMS to collect information such as cell voltage and temperature, and supports battery balancing. The information collected by the AFE chip needs to be processed by the MCU and calculate the state of charge (SOC). SOC is a relatively important parameter in the battery management system, because other parameters are calculated based on this parameter, so the performance requirements of the MCU chip are very high.
At present, BMS MCU is mainly distributed in NXP; the main suppliers of BMS AFE are Texas Instruments and Analog Devices. These manufacturers have mature technology and long-term research and development have accumulated a large amount of data accumulation, and can reach the technical threshold of automotive-grade BMS chips.
Battery Management IC (BMIC)
There are two types of BMICs, general purpose and special purpose. General-purpose chips include MCU, Power Management IC, communication interface, etc. Dedicated chips refer to the special development for BMS applications to meet the functional requirements of specific applications, including Battery Charger ICs, Battery Protector ICs, Battery Fuel Gauge ICs, Battery Authentication ICs, Battery Monitoring ICs, etc.
Battery Management ICs Applications
Battery Charger ICs mainly implement power path management and charge and discharge control functions. 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. Usually this type of chip is only used for charging low-power electrical appliances, and high-power applications such as electric vehicles generally use a dedicated high-power charging circuit composed of discrete devices.
The Battery Protector is mainly responsible for monitoring the charging and discharging of the battery cell and protecting the battery from damage caused by external factors. When a system abnormality is detected, the battery system is guaranteed to be safe by cutting off the circuit.
The power metering chip measures the external voltage, current, temperature and other characteristics of the battery, uses a specific algorithm to estimate the battery SOC/SOH and other parameters, and feeds back the results to the control chip. Some power metering chips also integrate protection functions.
The battery authentication chip is equivalent to the role of a ticket inspector. Authentication occurs when batteries are connected to the system, and only authenticated batteries can power the system. This is done to avoid damage to the device or the user from a mismatched battery.
The main function of the battery monitoring chip is to monitor the battery parameters with high precision, and send the relevant data to the main control chip through the communication interface. Generally, it is used in high-series series situations, and multiple monitoring chips need to be cascaded to form a monitoring system.
Electric Vehicles Accelerate BMIC Development
With the rapid development of electric vehicles, the requirements for battery systems are getting higher and higher in practical applications. At present, the battery voltage of electric vehicles is generally around 400V. Under the same power, the larger the voltage and the smaller the current, the smaller the heat loss during conduction. In this case, IGBT has no advantage in power consumption. SiC devices, on the other hand, are ideal for high-voltage platforms.
The breakdown voltage of common SiC devices is generally 1200V. Considering the safety margin, 800V has become the mainstream voltage configuration for high-voltage platforms of car companies. And the demand of AFE chip is directly proportional to the voltage. For a 400V system electric vehicle, about 8 AFE chips and 1 isolation communication chip are needed; for an 800V system, about 16 AFE chips and 1 isolation communication chip are needed. Therefore, with the popularization of electric vehicles, the demand for AFE will double.
Automobiles tend to be intelligent and electrified, and have higher requirements for safety. The main specifications include AEC-Q100, ISO26262 and IATF16949. AEC-Q100 is a stress test method for integrated circuits based on failure mechanisms, including a series of stress tests. Chips need to pass tests in scenarios such as high temperature and high humidity, vibration, and electrostatic discharge to obtain certification. ISO26262 is a functional safety certification for automotive chips, which aims to ensure that the system can respond correctly to external input and interference, and avoid causing damage to human health. IATF16949 is an automotive production quality management system certification covering product safety, risk management and emergency planning, embedded software requirements, change and quality assurance management, sub-supplier management, etc.
At present, suppliers that can provide complete solutions for automotive-level BMICs mainly include ADI, TI, NXP, Renesas, Infineon, onsemi, and ST. Among them, the AFE products of ADI and Renesas mainly come from their acquired product lines. The main difference of the AFE chip is the number of sampling channels, the number of internal ADCs, etc., which is technically difficult and has high added value. Major suppliers include ADI, TI, ST, NXP, Renesas. The car-grade ADC chip market is mainly controlled by TI and ADI.