0 1? Different voltage combinations?
From the overall evolution route, the main vehicle has gradually changed from a single voltage level of 12V to multiple voltage levels. The main development direction is:?
1) hybrid 12V+48V: two batteries, usually 12VAGM battery and 48V lithium battery as a match.
2) hybrid 12V+HV: two batteries, 12VAGM lead-acid battery and high-voltage lithium battery used in combination?
3) Electrification: mainly including 12V+HV, 12V+48V+ 12V, HV+48V (this design does not exist at present, but it is the direction of evolution)? What is worth mentioning here is the design of 48V power supply. The 48V voltage platform is usually used to supply power to loads that need higher power, and is connected to 48V? The ECU on V-voltage platform needs high efficiency, high power density and can withstand ISO? Power management equipment with working voltage requirements specified in 2 1780. Products such as buck regulators, three-phase gate drivers and battery management systems can be used in combination with current and voltage detection amplifiers. ?
Battery management system?
The main task of battery management system is to ensure the design performance of battery system. From the hardware structure, the battery management system consists of sensors, controllers, actuators, high and low voltage wiring harnesses, etc. From the hardware structure, it has the following functional modules:
1) battery parameter detection (sensor layer): including battery system total voltage, total current, single battery voltage detection, temperature detection, smoke detection, insulation detection, collision detection, etc. ?
2) Contactor control and battery safety protection (executive layer): The battery management system has circuits for driving contactors and diagnosing the actual state of each high-voltage node of contactors, and the contactors are integrated in the intelligent disconnection box under actual conditions.
3)MCU computing core: this part is the algorithm of the whole battery management system, and this part is also the most basic circuit structure of the battery system as a vehicle controller to achieve the established functional safety goals.
4) Equalizing circuit: The inconsistency of the whole battery system directly affects the actual available capacity of the battery system, and this inconsistency will accumulate over time. At present, with the battery entering the 200Ah era, the function and ability of balance has also entered a subtle era. ?
5) Power management circuit and EMC suppression: The battery management system drives the power supply from the battery module and 12V battery, and controls the power supply of different nodes through reasonable protection circuits.
6) Network communication and wake-up circuit: The battery management system needs to communicate with vehicle network nodes such as vehicle powertrain and body network, and also needs to carry out corresponding network management and wake-up sleep management.
7) Information storage unit: used to store key data, such as the usage of customers in the whole life cycle. The core content of this part is to record the time and frequency of battery system abuse data beyond expectations.
With the introduction of domain controller, information is stored in BMS, mainly in FOTA? Mainly, saving data is not an important thing. ? As shown in the following figure, if a huge and complete battery management system is to be completed on a circuit board, the complexity of its software and hardware, especially the mixed situation of high and low voltage, is more prominent, and the peripheral high and low voltage wiring harness makes the whole battery management system difficult to realize in hardware design. ?
Figure 1? Hardware basic framework of battery management system
Figure 2? A typical BMS circuit will be decomposed and analyzed later.
What are the evolution characteristics of chips in battery system and charging?
How to improve the reliability of battery management system?
Battery AFE test chip for Texas Instruments? (TI)？ Taking BQ79606A-Q 1 as an example, the main design direction is to improve the functional safety level and reliability of the chip at the chip level. Highly integrated BQ79606A-Q 1? Temperature and voltage levels can be accurately monitored, which helps to maximize battery life and driving time. In addition, BQ79606A-Q 1 Battery Monitor has the function of safety status communication, which can help system designers meet the requirements of automotive safety integrity level D(ASIL-D). This is ISO? The highest functional safety goal defined by the 26262 road vehicle standard. ? At present, in AFE, the functions of voltage detection, temperature detection and communication have all reached the safety integrity level ASIL-D? In communication, AFE occupies the main function. From the previous CAN, most enterprises have gradually transitioned to the daisy chain communication mode. In daisy-chain ring architecture, even if one communication cable is disconnected, all battery modules can communicate through reverse communication.
Figure 3? Daisy chain communication mode
In terms of design, powerful hot plug performance can be achieved without external Zener diode. At present, the battery system needs to optimize the charging and discharging performance at low temperature and ensure that the battery stays in a safe working area at high temperature. In order to apply proper thermal management strategy, it is necessary to carry out accurate voltage and temperature detection (BQ79606A-Q 1) at the battery/battery level. These may need to be preheated under cold start conditions and cooled at a higher temperature.
Summary: The development of BMS in recent years is mainly in the optimization of AFE chips, and the functional development of BMS itself is still relatively limited. With the iterative development of BMS and domain controller, this feature will become more and more obvious. As the leader of analog chips, TI has continuously introduced related automotive products and reference designs in recent years, such as those mentioned above? BQ79606A-Q 1 and the extensible 6s based on this product? Where to? Reference design 96s lithium battery monitoring demonstrator, and continue to develop a new generation of products to accelerate the innovation iteration process in this field. In addition, aside from the topic, I have recently seen many promotional activities of TI for the automobile market, which shows that TI attaches importance to the automobile field.
Figure 4? TI's advertisement in Anting subway station of Shanghai Automobile City?
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.