[YesAuto New Energy/Environmental Technology] Wanting to buy a car without a license has become an indescribable pain for people in cities that implement purchase restrictions. In that case, have you considered buying an electric car to relieve yourself? What? In recent years, the state has continuously increased its support for the new energy industry, especially for electric vehicles, and spared no effort. Various stimulus policies have been introduced one after another, so that there are many inherent advantages since the purchase link. Free lottery is one of them. However, as an emerging commodity, electric vehicles are very different from traditional fuel vehicles in terms of structure, parameters, and evaluation criteria. Many people are confused about how to choose and how to use and maintain. Therefore, today we will introduce to you in detail some of the basic knowledge you need to understand when buying an electric car, so that you can be more rational and confident before buying a car.
* Why does Autohome include some hybrid models in the scope of electric vehicles?
In terms of the various preferential policies for new energy vehicles promulgated by the state, electric vehicles are basically the main ones, including pure electric vehicles and plug-in (including extended range) hybrid vehicles. There are common features: it can be driven in pure electric mode, the power battery used does not include lead-acid batteries, and there is an external charging socket. In addition, the fuel cell vehicles contained therein also use electric energy to drive the vehicles. Based on the above reasons, and more in line with consumers, we collectively refer to pure electric vehicles, plug-in (including range-extended) hybrid vehicles, and fuel cell vehicles as “electric vehicles.”
● Interpretation of electric vehicle types
■ Pure electric vehicles
As the name implies, a pure electric vehicle is a vehicle driven purely by electricity. Although it is dubbed “new energy vehicle” which looks very avant-garde and full of sense of technology, the power system of electric vehicles is actually very simple, as simple as using two parts, regardless of the various appearances and equipment. It can be summarized: the electric energy storage system, which is the battery pack, and the electric motor that provides the driving force. If you look at pure electric vehicles from this perspective, you will find that Tesla’s luxury electric vehicles worth millions under the dazzling lights of high-end exhibition halls are actually no different from the mini four-wheel-drive vehicles that were played as a child. Of course, this is only in terms of driving form. The technical complexity of battery materials, battery management, electric motors, and on-board equipment of today's pure electric vehicles is far beyond your imagination, which is why the price of pure electric vehicles is often It's not cheap.
■ Plug-in hybrid models
Plug-in hybrid models are not popular in China, but the term “hybrid power” is no stranger to Chinese consumers. We can often see Japanese hybrid models represented by Toyota Prius and Lexus CT200h shuttle on the road. Plug-in hybrid power is a hybrid power that can be “plugged in”, so we need to first understand what a hybrid model is.
Hybrid power can be classified in many ways according to different definitions, one of which is to classify according to the degree of mixing of internal combustion engine and electric motor power. At present, the hybrid system generally used in China is classified according to the degree of mixing:
Micro-hybrid type: the ratio of the peak power of the motor to the rated power of the engine ≤5%;
Mild hybrid type: the ratio of the peak power of the motor to the rated power of the engine is 5%-15%;
Moderate hybrid type: the ratio of the peak power of the motor to the rated power of the engine is 15%-40%;
Severe hybrid type: The ratio of the peak power of the motor to the rated power of the engine is greater than 40%.
In addition, another common classification method is based on the connection method of the power system. The current hybrid models can be divided into three forms: series, parallel and hybrid. Among them, in the tandem form, the internal combustion engine does not directly provide power, nor can it drive the wheels alone, but only serves to drive the generator to charge the battery and provide electrical energy for the operation of the motor. This form is usually called an extended program, and we will introduce it for you in detail later.
Corresponding to the series connection is parallel connection. In a parallel system, the engine and the electric motor are mechanically connected to the wheels, which can drive the wheels individually, and can also work together to drive the vehicle together. At present, the parallel hybrid system is mostly used in micro-hybrid and light-hybrid vehicles, and the electric motor is more used as an auxiliary source of power when the vehicle starts and accelerates.
In addition to the series and parallel forms, the most commonly used is the hybrid system. The hybrid system combines the characteristics of series and parallel. The two power units can drive the vehicle individually or cooperate together. At the same time, the hybrid system has a separate generator, so it no longer uses the electric motor as a generator like a parallel system. Therefore, the engine can also charge the battery pack when working together with the electric motor, and theoretically, it can also realize the working mode of series connection (that is, extended range).
After understanding the classification of hybrid models, we will look back to understand what is a plug-in hybrid model. As the name implies, plug-in means that the power battery pack can be charged by intervening in an external power source. Theoretically speaking, as long as any of the above types of hybrid models meet this point, they belong to plug-in hybrid models. However, the most common plug-in hybrid models around us all use a hybrid structure.
■ Extended-range hybrid models
The extended-range hybrid model is structurally the series hybrid model we have talked about before. When the battery pack is fully charged, it runs in pure electric mode. When the charge is insufficient, the internal combustion engine in the car starts to generate electricity. The machine charges the battery and provides electricity for the operation of the motor. Since the internal combustion engine that only runs for power generation can run in a more economical working condition for a long time, compared with the traditional fuel model, the extended-range hybrid model still has the advantage of fuel consumption in the extended-range state, and it also has the smooth operation of electric vehicles. The advantages. At present, the most typical extended-range hybrid models we can see are Chevrolet's Volt Volt, BMW i3 extended-range version, and Fisker Karma, whose future is still unclear. Range-extended hybrid models use plug-in and engine-driven generators to charge the battery pack.
Of course, since all the extended-range hybrid models can charge the battery pack through the “plug-in” method, the extended-range hybrid models are also regarded as a more unique category among the plug-in hybrid models.
■ Fuel cell electric vehicles
A fuel cell is a battery that converts the chemical energy in the fuel into electrical energy by performing an oxidation-reduction reaction mainly through oxygen or other oxidants. At present, the most common fuel is hydrogen, and some hydrocarbons such as natural gas, alcohol, and methane are sometimes used as fuel. Fuel cells are different from primary batteries because they require a stable source of oxygen and fuel to ensure their operation and power supply. The advantage of this battery is that it can provide stable power uninterruptedly until the fuel is exhausted. The fuel cell model currently closest to mass production is Toyota's FCV, which is already expected to be launched in Japan in March next year and enter the European market in the summer of the same year. This fuel cell vehicle has two 70MPa high-pressure hydrogen storage tanks, equipped with an electric motor with a power of 122Ps (90kW) and a torque of 260N·m. It has a test cruising range of up to 700km in the Japanese JC08 mode.
The emission of hydrogen fuel cell vehicles is clean (theoretically only discharges water), which greatly improves the cruising range of pure electric vehicles. At the same time, when the fuel is exhausted, hydrogen fuel can be replenished as quickly as traditional fuel vehicles, without the need to charge for a long time. Of course, hydrogen fuel cell vehicles have high requirements for manufacturers' technical level, so it is relatively difficult to popularize at present.
● Electric vehicle power battery
Through the previous explanation, you must already have a certain understanding of the classification of electric vehicles, but if you want to buy an electric vehicle, it is obviously not enough to just understand how its categories are divided. As the power source of electric vehicles, the battery has always been regarded as an important landmark technology for the development of electric vehicles, and it is also an important bottleneck restricting the development of electric vehicles. Its performance is directly related to the length of the vehicle's cruising range. The relevant basic knowledge will be of great help to the purchase of electric vehicles in the future.
● Battery classification
In a broad sense, batteries can be divided into three categories: chemical batteries, physical batteries, and biological batteries. Among them, chemical batteries and physical batteries have been used in mass-produced electric vehicles, while biological batteries are regarded as important developments for electric vehicle batteries in the future. One of the directions. In consideration of the current practical application situation, we only introduce chemical batteries and physical batteries in detail. If you are also interested in biological batteries, you can refer to other materials.
■ Chemical battery
Chemical batteries are currently the most widely used battery type in the field of electric vehicles, such as nickel-hydrogen batteries, lithium-ion batteries, lithium polymer batteries, fuel cells, etc., all belong to this category. From a structural point of view, it can be further divided into two categories: battery and fuel cell. Most electric vehicles we have seen so far are driven by battery technology, such as Toyota Prius and Tesla MODEL S. Of course, the battery mentioned here is not the car battery we talk about daily, but a general term for rechargeable batteries. The lead-acid battery usually used in car batteries is only one of the sub-categories.
Since there are many types of electric vehicle batteries, most of them have been eliminated by the current market, and a long explanation of their obscure principles will not help the actual car purchase. So we first use a table to get a rough idea of these batteries. Types and basic characteristics, and then a detailed description of several common batteries on the market.
Note: As there are many types of batteries, only some representative categories are listed in our table.
|Brief analysis of batteries for electric vehicles|
|Types of|| Weight energy density
Nominal voltage of battery cell (usually)
Service life (times)
|Degree of commercialization||Representative models|
|Lead-acid batteries||30-50||Around 2V||it is good||500-800||Obsolete||–|
|NiMH batteries||70-100||1.2V||it is good||1000||Now using||Cash Prius|
|Lithium Ion Battery||Lithium Manganese Battery||100||3.7V||better||600-1000||Obsolete||Early Prius|
|Lithium Cobalt Oxide Battery||170||3.6V||difference||300||Obsolete|| Tesla
|Lithium iron phosphate battery||100-110||3.2V||it is good||1500-2000||Now using||Tengshi|
|Ternary lithium battery||200||3.8V||Poor||2000||Now use|| Tesla
Common chemical batteries for electric vehicles:
– lithium battery
Lithium battery is currently one of the most commonly used battery types in electric vehicles. Although it has not been a long time since its birth in 1970, it quickly occupied the largest market for electric vehicle batteries due to its high energy density and long cycle life. Part of the country. Nowadays, the lithium batteries equipped with electric vehicles on sale mainly include lithium iron phosphate batteries and ternary lithium batteries, and these two batteries have significant differences in their own characteristics, so it is necessary for us to explain and explain them in detail. Compared.
Why is lithium iron phosphate battery safe?
Most people may have little knowledge about batteries used in electric vehicles, so we might as well give an example to help everyone understand. Recently, a brand new electric car brand, Denza, jointly funded by BYD and Daimler, is about to go on sale, and it is equipped with a lithium iron phosphate battery. Compared with the earlier lithium manganese oxide batteries, the energy density of lithium iron phosphate batteries is not much different, about 100-110Wh/kg, but its thermal stability is the best among current automotive lithium batteries. When the battery temperature is at a high temperature of 500-600℃, its internal chemical components begin to decompose, and the lithium cobalt oxide battery, which is also a lithium battery, has an unstable internal chemical composition at 180-250℃. In other words, the safety of lithium iron phosphate batteries is second to none in lithium batteries, and because of this, it has become one of the main categories of current electric vehicle batteries .
Why did Tesla choose a ternary lithium battery?
Compared with the lithium iron phosphate battery, the ternary lithium battery used in Tesla MODEL S is much higher in weight energy density, about 200Wh/kg, which means that the ternary lithium battery of the same weight is higher than that of iron phosphate. Lithium batteries have a longer cruising range. However, its shortcomings are also obvious. When its own temperature is 250-350℃, the internal chemical components begin to decompose. Therefore, extremely high requirements are placed on the battery management system. It is necessary to install a safety device for each battery. In addition, Because of the small size of the cells, the number of battery cells required for a bicycle is very large. Taking MODEL S as an example, more than 7000 18650 ternary lithium batteries can meet the assembly consumption of a car. This is undoubtedly a further step for the battery management system. Increased the difficulty of control. Therefore, among the current models on the market, only Tesla uses ternary lithium batteries.
-Ni-MH batteries pay more attention to charge and discharge control
Ni-MH batteries are currently another mainstream type of electric vehicle power batteries besides lithium batteries. They have gradually developed after the 1990s. For example, many hybrid vehicles represented by Toyota Prius use such batteries as energy storage components. Its energy density is not much different from ordinary lithium batteries, about 70-100Wh/kg, but because the battery cell voltage is only 1.2V, which is 1/3 of the lithium battery, so under the condition of a certain demand voltage, its The volume of the battery pack is larger than that of the lithium battery.
Like lithium batteries, nickel-metal hydride batteries also need a battery management system, but they pay more attention to battery charge and discharge management. The reason for this difference is mainly due to the “memory effect” of NiMH batteries, that is, the capacity of the battery will attenuate during the cycle of charging and discharging, and overcharging or discharging may aggravate the capacity loss of the battery (for lithium batteries) Item characteristics are almost negligible). Therefore, for manufacturers, the Ni-MH battery control system will actively avoid excessive charging and discharging in settings, such as artificially controlling the battery's charging and discharging interval within a certain percentage of the total capacity to reduce the rate of capacity decay.
-Fuel cell is the most ideal energy source for future cars
The fuel cell is not actually a “battery”, but rather a large power generation system. It is recognized by the industry as the best energy source for future automobiles due to its high energy conversion efficiency, pollution-free, long life, and stable operation. Simply put, a fuel cell is a device that converts chemical energy into electrical energy through a chemical reaction, and the source of energy is mainly produced by the continuous supply of fuel and oxidant.
In theory, there are many types of fuels that fuel cells can use, even the fuel used in traditional internal combustion engines. However, the only thing that can really cause electrochemical reactions is the hydrogen and oxygen in the oxidizer. Therefore, hydrogen fuel cells are the current fuel. The core of battery research.
As far as today’s market is concerned, fuel cell vehicles are not far away from us. According to previous reports, the world's first mass-produced fuel cell vehicle Toyota FCV will be officially sold in Japan in March next year. The car is equipped with two 70MPa high-pressure fuel stacks with an output power of 122Ps (90kW) and a cruising range of up to 700km (under JC08 operating conditions in Japan). In addition, it only takes 3 minutes to add fuel, which is much faster than the charging time of traditional electric vehicles. At present, various policies related to it in Japan have also been formulated and promulgated one after another closely, but when it will be available in the country is still unknown, and we can only wait patiently for a while.
■ Physical battery
As the name implies, physical batteries are collectively referred to as batteries that rely on physical changes to provide and store electrical energy, such as supercapacitors and flywheel batteries, which belong to the family of physical batteries.
-Supercapacitors have high power density but small battery capacity
Supercapacitor is a kind of power element between traditional capacitor and battery. It mainly relies on electric double layer and redox pseudocapacitor charge to store electric energy. During this period, no chemical reaction occurs, so it is classified as a physical battery. Compared with the previously introduced chemical batteries, supercapacitors have three obvious advantages. First, they are repeatedly charged and discharged hundreds of thousands of times (traditional chemical batteries only have hundreds to thousands of times), and their lifespan is much longer than chemical batteries. ; Secondly, the power density of supercapacitors during charging and discharging is extremely high, and a large amount of electric energy can be released instantly, which can meet the wider power requirements of vehicles; thirdly, the adaptability of the working environment is better, usually the outdoor temperature is -40℃-65℃ It can work stably and normally (traditional batteries are generally -20℃～60℃).
Of course, if there are advantages, there are deficiencies. Low energy density is the primary bottleneck restricting the development of supercapacitors. Therefore, it is currently mainly used in vehicle starting systems, military and a small number of public transport vehicles. It will not be known until the energy density problem is broken.
-The flywheel battery is currently only used as an auxiliary battery
The flywheel battery is a new concept battery proposed in the 1990s, and it is also a type of physical battery. Simply put, it uses a principle similar to the energy generated when the flywheel rotates to realize its own charging and discharging. In the last round of the American Le Mans Series in October 2010, the Porsche 911 GT3 hybrid racing car officially used flywheel battery technology for the first time, and it was the predecessor of the famous Porsche 918 Spyder. However, the flywheel batteries of these two models are only used as auxiliary energy, and their functions are similar to our common braking energy recovery system. Even so, we still have reason to believe that with the continuous development of technology and the further reduction of prices, the application prospects of flywheel batteries will be very broad.
I have to admit that a large part of the factors that restrict the development or performance of electric vehicles at this stage are derived from battery technology. In the above article, we introduced the types of batteries used in electric vehicles that are currently available on the market. The charging and discharging speed and energy density of the battery are important, but as the motor that drives the wheels, its performance will also affect the driving performance of the electric vehicle. Just like batteries, various manufacturers are also exploring the application of electric motors.
In contrast, the development trend of electric motors is still clearer. From the perspective of mature motor technology, switched reluctance motors seem to be more in line with the needs of electric vehicles in terms of various technical characteristics, but they have not yet been popularized. Permanent magnet synchronous Electric motors have begun to be assembled on some mass-produced cars, such as Tenshi, BMW i3, and asynchronous motors are more widely used. In addition, if divided by current type, they can be divided into two types: DC motors and AC motors. Through the following table, we can roughly understand the performance characteristics of the next four more typical motors.
■ Brushless DC Motor
The battery stores electrical energy, and the electrical energy is transmitted from the battery output through the converter to the motor in the form of direct current. DC motors are divided into brushed DC motors and brushless DC motors. Brushless DC motors are replaced by brushless DC motors due to inconvenient maintenance. Brushless DC motors have become the most common type used in entry-level electric vehicles.
In terms of technical characteristics, brushless DC motors can be divided into brushless DC motors with DC motor characteristics and brushless DC motors with AC motor characteristics. The scope of our discussion is limited to the brushless DC motors with the characteristics of the more mainstream DC motors.
According to the technical requirements of electric vehicles for electric motors, DC motors can meet the basic needs of electric vehicles. In addition, brushless DC motors do not require users to consider its maintenance during the use of the car. Based on such characteristics, brushless DC motors Become the first choice for entry-level electric vehicles.
The reason why it is the first choice for entry-level motors is that this motor itself also has some drawbacks, which will hinder its development in the electric vehicle industry.
The speed range of DC motors is not wide, and the maximum speed is only about 6000rpm. Such speed attributes are difficult to meet the needs of electric vehicles. Therefore, some manufacturers match them with two-stage reducers or have a certain transmission gear ratio range. CVT gearbox to make up for the shortcomings of the DC motor in terms of speed. Obviously, such a technical structure has an adverse effect on the design of the vehicle in terms of space layout and weight control. Of course, it is also possible to match the electric motor with a single-stage reducer, but the dynamic performance of the vehicle and the maximum speed will be affected.
■ Why are asynchronous motors the most widely used now?
The reason why a product or a technology is widely used must be inseparable from the balance of cost and function. The popularity of asynchronous motors in the field of electric vehicles can illustrate this point. In addition to the electric vehicle products launched by most domestic manufacturers, the fans of asynchronous motors also include the Tesla MODEL S, which is unique in the electric vehicle camp. In terms of technology, why can asynchronous motors be popularized?
Asynchronous motors can also be summarized into the category of AC motors. Frequency conversion speed regulation is the first function of the electric motor, because the wheels of a pure electric vehicle are driven by a transmission mechanism composed of an electric motor and a differential. The speed range of the electric motor itself can meet the driving needs of the vehicle. Therefore, from the technical structure Look, the gearbox is no longer a necessary device for the entire power system. However, in terms of the performance of frequency conversion speed regulation, higher requirements are still placed on the electric motor. In addition, reversing is also a problem often encountered in daily driving. The motor needs to be able to freely switch between the forward and reverse states.
The asynchronous motor has the ability of variable frequency speed regulation, and its effect is equivalent to the relatively linear correspondence between the engine speed and the vehicle speed when the vehicle equipped with a continuously variable gearbox is accelerating. As for the reversing problem mentioned above, the asynchronous motor can also be easily satisfied by its own forward and reverse switching.
It is also easier for asynchronous motors to realize kinetic energy recovery. When the vehicle is coasting or braking, the wheels reverse to drag the motor to rotate. Under this working condition, the motor can generate electricity and recover the electrical energy into the battery, thereby extending the vehicle's cruising range.
Functionally, it can meet the technical requirements of electric vehicles, but its own structure is not complicated, which brings advantages such as sturdiness and durability, stable working conditions, and easy-to-control costs.
■ What type of motor is better
-Permanent magnet synchronous motor
In fact, the structure of the permanent magnet synchronous motor is similar to the DC motor mentioned above, so that it can have the characteristics of simple structure, reliable operation, high power density, and good speed regulation performance of the brushless DC motor. At the same time, since the drive mode of the permanent magnet synchronous motor is different from that of the DC motor, the permanent magnet synchronous motor is better in terms of noise and control accuracy.
The use of permanent magnet synchronous motors is also helpful to the riding comfort of electric vehicles. Under normal circumstances, we regard the quietness of the passenger compartment as one of the factors to measure the comfort of a car. For general users, this measurement standard is also applicable to electric vehicles. Most of the current electric vehicles only provide a one-stage reducer. Therefore, the speed of the electric motor is relatively high. It is affected by factors such as the driving mode of the electric motor, the assembly accuracy and the matching between various components. The noise emitted by the electric motor when the vehicle is running may affect the interior The ride comfort of the occupants. Of course, we can’t take the role of the sound insulation of the whole vehicle, but only to evaluate the control of the noise source, the permanent magnet synchronous motor still has certain advantages, in addition, its volume is also smaller, in other words, the layout is more flexible and lighter. Its own weight also contributes to the weight of the vehicle. The BMW i3 uses a permanent magnet synchronous motor.
Why doesn't Tesla use permanent magnet synchronous motors
From the perspective of technical advantages, permanent magnet synchronous motors should become a must-use type for high-end electric vehicles, but things are not so absolute. Tesla MODEL S uses the asynchronous motor type described above, although in terms of weight and volume, Asynchronous motors are not dominant, but their wide range of speeds and peak speeds of up to 20,000 rpm can meet the speed requirements of high-speed cruising of this class of vehicles even if they do not match the secondary differential. As for the impact of weight on cruising range, high energy density The 18650 battery can “cover” the disadvantage of the motor's weight. In addition, the excellent stability of the asynchronous motor is also an important reason why Tesla chose it.
-Switched reluctance motor
Switched reluctance motor is a motor with great development potential. In addition to the advantages of simple structure, sturdiness and durability, reliable work, and high efficiency, its speed regulation system has more controllable parameters and economic indicators than the above motors. The power density is also higher, which means that the motor is lighter and more powerful, and can achieve 100% starting torque when the current reaches 15% of the rated current. In addition, the smaller size also makes the design of the electric vehicle more flexible, which can contribute more space to the vehicle. More importantly, the cost of this motor is not high.
-Having said so many advantages, why can't this type of motor be popularized yet?
Although the structure of the switched reluctance motor is simple, the design of the control system is relatively complicated, especially in the research and development stage, it is difficult to establish an accurate mathematical model for the existing technology. In the actual operation process, the noise and vibration emitted by the electric motor itself cannot be “tolerated” by the electric vehicle. These two points are especially obvious when the load is running. In summary, this type of motor may be widely used in the field of electric vehicles under the premise that technology optimization can overcome fatal injuries in the future, which can help the range of electric vehicles to increase.
-Motors that have been born 100 years ago and still cannot be widely used
The in-wheel motor, which was born 100 years ago, is still in the conceptual stage. At present, many supporting manufacturers are able to come up with design solutions for in-wheel motors and drive axles, but few manufacturers can adopt them. In-wheel motors give unsprung quality. Bringing an excessive burden is one of the reasons hindering its development.
At this stage, in addition to the battery capacity, electric motor and other issues mentioned above, charging technology is also one of the factors that hinder the popularization of electric vehicles. How to charge electric vehicles intelligently and quickly is the most important research and development of many automobile manufacturers. For electric vehicles, the charging device must meet the requirements of safety, convenience, economic cost, efficiency and other aspects. At present, the common charging methods on the market include conventional charging methods such as charging pile charging stations, wireless charging methods, Replacement battery.
■ Regular charging
At present, some commercially available electric vehicles are equipped with portable charging equipment. Owners can use the portable charging equipment that comes with the vehicle to supplement the electric energy of the vehicle by using civil or commercial electricity, or they can go to special charging stations or charging piles for charging.
At present, the portable charging equipment that comes with the car allows most of the current to be 10A or 16A. With these portable charging equipment, you can use the socket at home to charge, but it should be noted that the socket at home also includes the distinction between 10A and 16A. The sockets used are generally 16A, and the sockets for most other electrical appliances are 10A. Different currents will have a certain impact on the charging time of electric vehicles.
■ Fast charging
The conventional charging method takes about 8 hours to fully charge the battery, so many car owners choose to charge their car at night or when the electricity bill is low. When it takes a very short time to fully charge the battery, the conventional charging method appears “stretched”. At this time, it is time for fast charging to appear. Recently, the popular Tesla in the field of electric vehicles supports the fast charging mode.
This charging method generally uses a high charging current to charge the battery in a short time. Although the equipment installation cost is higher than that of the conventional charging method, the charging time is very close to the time of refueling the internal combustion engine.
However, it should be noted that not all electric vehicles can be fast-charged. This is because during fast charging, the battery will withstand a larger current “impact” in a short period of time, which will cause overheating of ordinary batteries, which poses a safety hazard. Therefore, at the beginning of vehicle development, a special battery needs to be selected for fast charging. Of course, no matter how the battery is optimized, fast charging will have a certain impact on battery life.
■ Wireless charging
In the above conventional charging method, whether it is the traditional method using 16A, 10A current or the fast charging using high charging current, it will be “fettered by the wire”. The charging device and the line used during charging will make it more or less affected by the venue. Restrictions, wireless charging solves this problem to a certain extent. The power supply coils arranged on the ground and the power receiving coils at the bottom of the vehicle are often used to charge the vehicle through the magnetic resonance generated between the coils instead of the traditional power line. However, this charging method requires a higher distance between the power supply and receiving coils.
■ Replace the battery
In addition to the car charging method mentioned above, there is also a special “charging method”, which is to replace the battery pack. This charging method is to replace the exhausted battery pack with a fully charged battery pack through a specific replacement station when the vehicle battery is exhausted.
The following video is a demonstration video of battery replacement for electric vehicles provided by BAIC New Energy that we took at the exhibition. The battery is replaced by a robotic arm, which is faster than manual replacement.
At present, the battery replacement speed of electric taxis in some areas of Hangzhou can be controlled within 5 minutes, but this method of battery replacement requires different brands and models to match the same battery pack, and the physical size and electrical parameters of the battery need to be unified. In addition, there are problems such as the inability to ensure that the battery quality is consistent, and the construction of base stations is too small, which restricts the promotion of this method of battery replacement in the country.
As far as the domestic policies have been introduced, avoiding lottery is the biggest driver for purchasing electric vehicles. But how to choose an electric car that suits you is still the most important problem for individuals. Through the above introduction, the current range of electric vehicles on the market that use nickel-metal hydride batteries, lithium iron phosphate batteries and ternary lithium batteries can basically meet people’s daily travel needs, and with the gradual improvement of infrastructure and laws and regulations, It will also become more convenient to use.
Of course, some people may still be afraid of pure electric vehicles and worry about the inconvenience caused by the limitation of cruising range. In this case, plug-in hybrid models are also a good choice, although they do not require refueling as pure electric vehicles, but It has obvious advantages in terms of cruising range and regional adaptability, which can dispel the worries of long-distance travel. In general, no matter what kind of electric car you choose to buy, you can only enjoy the pleasure and convenience brought by it if you have a detailed understanding of the relevant knowledge and a rational choice. (Photo/Text Autohome Technology·Design Channel)