1、 Composition diagram of portable energy storage box
The household energy storage industry has become more and more popular in Europe and the United States after the development in recent years. It is a small wind outlet industry.
With the development of 5G, the miniaturization of base stations will gradually spread, and the demand for emergency power supply will increase; Outdoor self driving tours are popular, and small energy storage boxes are increasingly used in both consumer and industrial fields; After ten years of optimization, our team has optimized a perfect solution in terms of quality and cost.
2、 Lithium battery
After a period of development, there are two mainstream materials: lithium ternary and lithium iron phosphate; At present, super capacitors also have a part of the market share.
The main characteristics of the two materials: the capacity density of lithium terpolymer is higher than that of lithium iron phosphate, the unit price of lithium iron phosphate is lower, and the safety is good; The main feature of super capacitor is that the cycle times of charge and discharge are more than lithium battery, but the price is high.
At present, lithium batteries made of two materials have a certain market share in household energy storage; If the unit price of lithium iron is further reduced in the future, considering the cost of energy storage consumption, I am more optimistic about lithium iron phosphate; At present, there are many domestic battery manufacturers in the market, but the consistency still needs to be improved. The consistency is not good. Even if the balance is well done, the battery life and charging and discharging times will also be affected.
3、 BMS lithium battery protection board
After years of development, the high-end of lithium battery protection plate is electric vehicle; The BMS protection board for energy storage is relatively simple. At present, there is no national standard to define a specification. Everyone plays their own.
1> At present, the main front-end sampling chip solution providers are as follows:
Compare the sampling IC schemes of the analog front end with those of the mainstream manufacturers. No specific model is shown, but the model recommended by the manufacturer is attached.
Features of IC models promoted by IC manufacturers Functional analysis of current mainstream application markets
Renesas ISL78600 can manage up to 12 strings of batteries, and can be distributed and combined 25
TI BQ76940 (BQ series) 12~15, good supply, market mainstream STM8S105K4T6C+11
ADI AD7280A
Japan's ROHM ML5238 supports 16 strings. It has requirements for power on sequence. The accuracy rate is average. SPI interface communication. The equalization is passive equalization. With current and voltage monitoring functions, we have a very mature scheme. After several generations of optimization:
582800448 18 (15 large batches)
Infineon XC886CM (MCU) IPD70N03L (MOS tube) IPD70N10L (PMOS) TLE7273/TLE6250 (can) has a small supply, so it is not considered
Linglilte LTC6811 (acquired by ADT) LTC68 series, with multiple strings (12 strings for this model)
Max14921/MAX17853 16 strings, with better accuracy than ML5238, are all passive equalization 28
ATMEL ATA6871/ATA6870 QQ
ST
Domestic VAS5118 is compatible with 3 to 28 batteries
Analog front-end sampling chip is the main competitive market of semiconductor giants, and also the main component of BMS protection board; At present, both Rom and TI are adopted in our program; Of course, there are also some domestic and Japanese brands that have a certain share in the market, so we can consider the options according to the cost and use occasions.
2) MCU management part
The main functions of MCU in the protection board are SOC estimation, battery equalization, charged and discharged protection; At present, the main difficulties of various BMS protection boards lie in the accuracy of SOC estimation and the safety of protection.
There are three main algorithms for SOC:
Voltage calibration method, voltage calibration method+current integration method, Kalman filter estimation method.
At present, voltage calibration method+current integration method are commonly used, and Kalman filter estimation method is adopted for electric vehicles; At present, our scheme adopts simplified Kalman filter estimation model+current integration method; In the early static state, an initial capacity value is obtained by voltage calibration method, and then the data is converged by Kalman filter.
3) MOS tube part
At present, MOS tubes are the main cost of the protection board hardware. At present, most of the MOS tubes used in the energy storage field and electric bicycles are made in China; We can customize according to customers' requirements.
4、 Inverter
The inverter technology has become very mature after years of development. At present, there are many mature schemes in the market, so we will not list them one by one; At present, the comparison process in the market is the ST scheme, which has a great cost advantage. We also adopt this scheme at present.
