Briefly describe the gap between BYD and TSLA Nickel Hydride No. 5 battery and electronic control technology!

Introduction: Tesla has brought the Silicon Valley spirit to North America with its 3.9-second acceleration from 0 to 100 km/h and a 17-inch central control screen that kills all physical buttons. BYD is closer to the Chinese character, not adventurous and not high-profile. It starts with the desire to popularize new energy vehicles, penetrates the public transportation field, and gradually develops low-priced, civilian hybrid and electric vehicles. In addition to BYD and Tesla, there will be more new energy vehicles in China in the future.

The future of electric vehicles represents silence and patience. But the representatives of China and the West on the crest of the wave: BYD and Tesla, have something to say.

The situation of lithium iron phosphate and nickel cobalt aluminum batteries

When motor and control technologies are well-documented and becoming more mature, the most difficult dilemma and the biggest competition for electric vehicles come from Nickel Hydride No. 5 battery technology.

Tesla used a very small 18650 lithium cobalt oxide Nickel Hydride No. 5 battery in its early Roadster electric sports car. This Nickel Hydride No. 5 battery is usually used in small appliances such as mobile phones and laptops. Its biggest feature is that it has a very high energy density, almost reaching 170 watt-hours/kilogram. However, its thermal stability has also been criticized. It will decompose and produce oxygen at around 180 degrees.

Tesla Nickel Hydride No. 5 battery cell

Later, in order to compromise energy density, power density and safety, Tesla used modified ternary nickel-cobalt-aluminum batteries on the Model S, bringing the total number of batteries to more than 8,000, more than 1,000 more than the Roadster, but the cost has dropped by 30%. Despite this, the very limited number of cycles still becomes a problem that hinders the application of such batteries in electric vehicles. Calculated at a charging frequency of once every two days, the Nickel Hydride No. 5 battery will die in about three to four years.

Tesla's solution to this is to provide a "no-fault" Nickel Hydride No. 5 battery warranty policy, that is, as long as the Nickel Hydride No. 5 battery is not damaged by human damage or collision accidents, it can get an eight-year free warranty. And when the Nickel Hydride No. 5 battery life expires, Tesla will bear the Nickel Hydride No. 5 battery recycling and replacement. Such a policy will bring great pressure to Tesla with the launch of entry-level models and the increase in sales. This may also be one of the reasons why it is preparing to build the world's largest Nickel Hydride No. 5 battery factory.

In contrast, the lithium iron phosphate Nickel Hydride No. 5 battery used by BYD is currently the most widely used Nickel Hydride No. 5 battery. Its advantage is that it has high thermal stability. Its structure is still relatively stable at 600 degrees. At the same time, because the trivalent iron ions are not active, it is difficult to undergo chemical changes, which makes its life relatively long. In theory, it can be longer than the life of the whole vehicle, and the cost of long-term use is low. At the same time, the power density of lithium iron phosphate batteries is relatively good, it can be discharged at a large rate, and has good acceleration performance.

BYD Nickel Hydride No. 5 battery pack

However, compared with ternary lithium batteries, the energy density of lithium iron phosphate batteries has no advantage, which is about 100~110 watt-hours/kilogram. This leads to a shorter cruising range under the same weight. If you want to achieve a higher cruising range, you will inevitably need to increase the weight of the Nickel Hydride No. 5 battery and increase the cost.

In terms of comprehensive performance, not all companies have Tesla's software capabilities and Nickel Hydride No. 5 battery management capabilities, so lithium iron phosphate batteries are still more optimistic and more pragmatic Nickel Hydride No. 5 battery types. This may also be one of the reasons why GM is preparing to adopt lithium iron phosphate batteries.

Because of the characteristics of the Nickel Hydride No. 5 battery, Tesla has carried out very in-depth design on its Nickel Hydride No. 5 battery arrangement, thermal management system, and Nickel Hydride No. 5 battery management system to ensure that each Nickel Hydride No. 5 battery cell is under supervision and its status data can be fed back and processed at any time. For a single small Nickel Hydride No. 5 battery cell, Tesla will enclose it independently in a steel compartment, and the liquid cooling system can cool each Nickel Hydride No. 5 battery cell to reduce the temperature difference between each other, which also relatively reduces the risk of Nickel Hydride No. 5 battery spontaneous combustion.

The reason for the Tesla accident is mainly due to the local short circuit of the power line caused by the puncture of the Nickel Hydride No. 5 battery pack. At present, Tesla cannot solve the situation where the Nickel Hydride No. 5 battery pack is burned and exploded under extreme damage by the impact force, but the high-intensity protection buys more time for the owner to escape.

In fact, this is almost a common potential hidden danger of electric vehicles, and it puts forward very high requirements for the function of the Nickel Hydride No. 5 battery management system. In addition to the daily supervision of Nickel Hydride No. 5 battery temperature and working status, it is also necessary to cut off the high-voltage line immediately when the temperature changes rapidly or an extreme collision occurs. The upgrade of the thermal management system and the Nickel Hydride No. 5 battery management system will also shorten the Nickel Hydride No. 5 battery charging time and bring higher charging efficiency.

In addition, how to ensure the charging and use efficiency of the Nickel Hydride No. 5 battery in a low temperature environment is a problem that companies engaged in the research and development and production of electric vehicles need to solve.

It is also worth mentioning that Tesla has been promoting pure electric vehicles, and its high-end product line, from high to low, also reflects from the side that the market's tolerance for electric vehicles is far from enough.

BYD's future "dual engine dual mode" car is actually to promote plug-in hybrid vehicles as transitional products before the electric market is truly opened. Compared with traditional gasoline vehicles, hybrid vehicles are more fuel-efficient and reduce the amount of batteries. Considering the policy subsidies for new energy vehicles, the cost of purchasing a car has also been reduced. This is in line with BYD's product idea for popularization.

Synchronous and asynchronous, the choice of motor

In the process of leaving the Nickel Hydride No. 5 battery and reaching the motor, the current needs to be "transformed" from direct current to alternating current that meets the motor drive through an inverter, and then input into the motor, and the drive circuit drives the motor to rotate and output torque. In terms of the idea of motor selection, Tesla uses asynchronous motors with more mature technology and a wide range of applications for the sake of conservatism, while BYD, which is positioned for popularization, has a bit of incomprehensible stubbornness and chooses relatively "difficult" permanent magnet synchronous motors.

There is no essential difference between the two in terms of working principle. Both rely on electromagnetic induction between the stator and the rotor to generate and output torque. The asynchronous motor establishes the rotor magnetic field through the stator winding, while the permanent magnet synchronous motor, as the name implies, uses permanent magnet materials in the rotor part. Choosing a suitable motor will also have a certain compensatory effect on the decline in Nickel Hydride No. 5 battery power, which will save some Nickel Hydride No. 5 battery costs.

The reserve technology of asynchronous motors is relatively mature, and the operation is reliable and long-lasting. Whether it is a high-power motor in a factory or a refrigerator or washing machine at home, it can almost be seen. This is a very rational and simple choice for expensive electric vehicles. But at the same time, compared with other electrical appliances, the more meticulous pursuit of electric drive parts by electric vehicles also highlights the shortcomings of asynchronous motors. In addition to consuming more electricity, its rotor is also easy to heat up, and the speed-up performance is relatively ordinary.

In order to improve the disadvantages brought by asynchronous motors, Tesla first made a fuss in the electric adjustment part, using IGBT to meet efficient power conversion control, and reorganized the electrical connection between the motor and the gearbox to increase the output torque of the motor at low speed.

The permanent magnet synchronous motor used by BYD has been greatly improved in terms of efficiency and power density. Its speed-up performance is faster than that of asynchronous motors, and its structure is simple and relatively easy to maintain. However, its technical reserves and application fields are not yet mature, and the high cost of rare earth materials contained in permanent magnets has always been a chronic problem of permanent magnet synchronous motors. BYD made such a choice, on the one hand, saving the adjustment of the drive device to the power demand, but on the other hand, it also brought difficulties to cost control. And how to make the magnet play its original efficiency with lower rare earth materials may still require BYD to continue thinking.

Integration and reshaping, who is closer to the future

With the arrival of the Model S, Tesla has repeatedly subverted its charging time, and has expanded the number and coverage of super charging piles, as well as its leading car-making concepts and sales models, making it the "Apple" company in the automotive industry for a while. But in the eyes of many traditional automobile companies, Tesla's sudden appearance is not enough to have a subversive impact on the automotive industry. And there are still many differences in the understanding of the existence of new energy vehicles.

Among independent brands, "making a Tesla in minutes" has become a popular phrase. BYD, also a new energy vehicle company, was the first to make bold statements, and recently, Geely's boss Li Shufu also expressed similar ideas. In the original, perhaps it is because behind Tesla's advanced car-making concept, it reflects its strong technology integration and integration capabilities. From the selection of its batteries and motors, Tesla intends to refine the existing and relatively mature technologies, reduce the innovation costs of basic product technologies, and maximize the integration potential between components.

For automobile companies that are also engaged in basic technology research and development and matching, Tesla is still difficult to be regarded as a strong automobile company. Starting with high-end models and temporarily lacking civilian models also makes its "revolution" in the new energy field less convincing, but this is complementary to Tesla's development history.

In fact, BYD, which has also been making cars for ten years, has not yet established an absolute advantage in the field of new energy vehicles, and even needs to frequently deal with doubts and comparisons from all sides. But it is worth noting that BYD and Tesla have different product ideas. Relying on the vertical integration of the industrial chain, BYD has taken over the independent production of most parts. In addition, the core technology and control unit of the dual-engine dual-mode also come from independent research and development. Compared with Tesla's innovation and extreme pursuit of integration capabilities, BYD chose to find breakthroughs from the perspective of emerging technologies, which is closer to the foundation of innovation, but at the same time it also poses a great challenge to the company's technical strength reserves.

Summary

Traditional automobile companies have accumulated many years of experience in car manufacturing, but they are unable to devote too much energy to new energy vehicles, which is putting the cart before the horse; while companies focusing on new energy vehicles give their products more technological colors, they are limited by their thin experience in car manufacturing and it is difficult to avoid flaws.

Ten years ago, the electric vehicle market was almost flat, shrinking in a corner of automobile products and rarely in demand. With the technological breakthrough of lithium batteries, electric vehicles have gradually gained three-dimensional and abundant opportunities. This opportunity is also a long-awaited moment for companies pursuing new energy vehicles.

Tesla has brought the Silicon Valley spirit to North America with its 3.9-second acceleration from 0 to 100 kilometers and a 17-inch central control screen that kills all physical buttons. BYD is closer to the Chinese character, not adventurous, not high-profile, starting from the desire to popularize new energy vehicles, penetrating the public transportation field, and gradually developing low-priced, popular hybrid and electric vehicles. In addition to BYD and Tesla, there will be more new energy vehicles in China in the future.

Confrontation and competition first require the market to mature and absorb. Before this, new energy vehicles faced similar difficulties in terms of technology, policy, environment and product positioning. Just like panning for gold in the mud at the bottom of a river, in addition to constantly sifting with your arms and keeping your eyes focused, you also need the push of time to sink the unnecessary turbidity back into the river, leaving only the clear.

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