Views:9 Author:Site Editor Publish Time: 2020-02-26 Origin:Site
With the development of the times, electric vehicles have begun to appear. Because the power source and energy source of electric vehicles are completely different from traditional gasoline vehicles. As a result, many "electric vehicle companies" have also begun to emerge. In the field of electric vehicles, they have stood on the same starting line as traditional fuel vehicle brands. This is also known as The origin of "curve overtaking". We can look at the technical differences between the two industry leaders, Tesla and BYD.
Tesla adopts a Panasonic lithium cobalt oxide battery, while BYD choose a self-developed high-power lithium iron phosphate battery combination. The largest difference between the two is that lithium cobaltate batteries are harmful to the environment, and lithium iron phosphate batteries are green. But the advantages of lithium cobaltate batteries are also very obvious. Compared with lithium iron phosphate battery, lithium cobaltate battery technology is more mature, with high power and high energy density. So Tesla's electric vehicle has better endurance and speed-up capability than BYD.
In terms of motors, Tesla uses asynchronous motors, and BYD uses permanent magnet synchronous motors. Asynchronous motor technology is also more mature and more durable than permanent magnet synchronous motors. But it also consumes more power than a permanent magnet synchronous motor, and its speed-up performance is not as fast as a permanent magnet synchronous motor. In addition, the structure of the permanent magnet synchronous motor is simpler, so it is easier to maintain.
In addition, Tesla and BYD each have their own characteristics. For example, Tesla's battery management system for electric vehicles can effectively monitor battery physical parameters. And BYD's two-way countercurrent charging and discharging technology can integrate the drive motor with the vehicle charger and DC charging station into one, to better achieve the purpose of charging and discharging.
From these aspects, Tesla and BYD have their own advantages in the three aspects of motors, batteries, and electronic control. As the absolute core of electric vehicles, the three-electric system is just as important as the engine of a fuel vehicle also it is the core of the entire electric vehicle's power system. But the three-electric system is actually not the same as a fuel vehicle, it can be strong in one aspect but weak in another. The three-electric system is a tightly connected system. The poor performance of one of the three modules will directly affect the driving experience of the entire vehicle.
For electric vehicles, all energy storage is based on batteries, the performance of the battery (specific energy, energy density, specific power, cycle life, cost, etc.) has a close relationship with the range, power performance, etc. of the electric vehicle. With the same energy consumption and the same battery pack volume and weight under the strict restrictions, the single mileage of an electric vehicle mainly depends on the energy density of the battery. The energy density of gasoline is 12000w / kg, but now the battery with the highest energy density is generally around 310w / kg. According to expectations, in the next 2030, the energy density of the battery will reach 500Wh / kg, which is also extremely lower than that of traditional gasoline.
Lithium batteries with higher specific energy are now commonly used. Now mainstream lithium batteries are ternary lithium batteries and lithium iron phosphate batteries. Generally speaking, the energy density of a battery pack system with a ternary lithium as a positive electrode is higher than that of a battery pack system with a lithium iron phosphate as a positive electrode. Lithium battery size, material of the positive and negative electrodes, compaction density, battery pack group efficiency etc., all will affect the performance of the battery.
The electric motor is equivalent to the engine of a fuel vehicle and is used to drive the vehicle. At present, most pure electric vehicles use DC motors, and DC motors can be divided into asynchronous DC motors and synchronous DC motors. Among them, the asynchronous DC motor withstands relatively large power and is relatively small in size, but its own noise is larger than that of the synchronous motor, and it will emit some unpleasant howling sounds during sudden rapid acceleration and slowdown. And some hybrid models will prefer to use DC synchronous motors. Because the power that most synchronous motors can adapt to is not high, it is difficult to meet the power requirements of today's pure electric vehicles. However, hybrid vehicles do not require high motor power, so most of these motors are installed on some hybrid vehicles.
Electric control system
The role of the electronic control system is to manage every detail of the entire power system, from battery temperature & battery output, to motor output power, to battery life, and environmental monitoring, etc. The electronic control system is actually the brain of a pure electric vehicle. The operating conditions of the electronic control system are relatively complicated: it needs to be able to start and stop frequently, accelerate and decelerate frequently; it requires high torque at low speed / climbing, low torque at high speed. Also it shall have a large speed range; for hybrid vehicles, it also need to handle motor startup , Motor power generation, braking energy feedback and other special functions.