The next outlet: the era of super fast charging of electric vehicles

This article is based on publicly available materials and is for informational purposes only and does not constitute any investment advice.

Guest: Ni Feng Deputy Secretary-General of the Standardization Committee of Electric Vehicle Charging Facilities in the Energy Industry, Deputy Director of the Experimental Verification Center of the State Grid Electric Power Research Institute

Endurance has always been an important demand for new energy vehicles, and in 2022, new car-making forces will successively launch high-voltage platforms to meet the voltage of fast charging. For the car endurance, there are two schemes of charging and power exchange, what will be the choice of mainstream automakers?

What are the requirements for charging and replacing the whole vehicle, and which is the better safety performance? What is the market space for charging and swapping?

01

Application of charging piles and substations

Charging technology I personally think is more suitable for passenger cars, including private cars, official cars These application scenarios are more random, and there are more occasions with more demand for car diversity; power exchange is more suitable for dedicated application scenarios, such as some operating vehicles.

This is determined by their technical characteristics: charging involves relatively fewer technical problems than power exchange. Charging is mainly to solve the problem of energy replenishment; and in addition to charging the battery, the power exchange also requires some other equipment, such as the equipment for battery replacement and the equipment maintained in the power station. In addition, the replacement of the battery requires a backup battery, because the principle of the power exchange is to reduce the time of energy replenishment by using the backup battery.

At present, there is a very big problem of power exchange, which is difficult to solve by standardization, and the problem of standardization is a very important reason that affects the development of power exchange technology now. Charging is mainly a problem of the interface, so the development of charging technology is limited by standardization than the power exchange technology, and a large reason for the development of charging technology is the battery.

Some manufacturers are now pushing and replacing the power model, individual manufacturers may be able to create a model, the premise is that the manufacturer must first be able to withstand the cost of the power exchange, of course, the cost of rising problems manufacturers can be solved by capital operation, but the standardization problem of power exchange is very difficult to solve, there is no way to build a power station to cover all the scenes.

02

The demand for slow charging is still higher than that of fast charging

In the long run, in terms of quantity, the speed of slow charging will be much higher than that of fast charging, or the so-called power exchange, which will be much more than it, because I just talked about the scene of the vehicle, especially now our ordinary home scene, it drives far less than the time of parking, in fact, as long as the parking space can solve the problem of charging, it is completely enough for daily use.

Only when you have a long trip, you will need some of this fast charging, so in the long run, the number of such small and medium-power charges will be much more than the so-called fast charging and replacement.

03

Charging standards are distinguished

Generally speaking, we are divided into two categories: DC charging and AC charging.

AC charging ground facilities are very simple power are relatively small, the general like a single phase is generally below 7000 watts, this is our Chinese standard, European and American standards may be slightly larger, three-phase communication may be able to be slightly larger, then the highest in accordance with our China's highest energy to 40 kilowatts.

In terms of the DC part, internationally it is also divided into level 1, level 2 ratings. The distinction between high power and ordinary power is generally based on the size of the current. China is bounded by 250 amperes, while the standard in Europe and the United States is basically bounded by 200 amperes. But this can only be used as a reference, because the power of the charger does not determine the speed of the final charge, the speed is still determined by the vehicle. If the vehicle's battery does not allow such a fast speed, then the charger can not be charged fast no matter how big.

Slow charging generally refers to less than 20 kilowatts. Looking further up, the general use on the highway is 60 kW - 120 kW, called medium speed charging. When the charging current exceeds 250 amps, we define it as high-power charging.

There may be a way to charge ultra-advanced in the future, called MCS, megawatt Charging System. At present, there are also many companies in the world that are studying MCS, and its space power will reach the level of more than megawatts, which is also preparing for future ultra-fast charging or heavy vehicles.

As for the division of grading, there is still a big difference between domestic and foreign. The rating is actually derived from the definition of the J1772 standard in the United States, indicating 120 volts of alternating current, but 120 volts of AC is not available in China, it is the power supply system of the United States, as well as Japan, and The voltage level used in Taiwan in China.

04

The unification of charging interfaces is of great significance

At present, there are indeed several mainstream standards in the world, including three systems and 4 interfaces.

One is the standard of Europe and the United States. Europe and the United States actually use the same system, they are the same in the control logic and communication protocol, but the charging interface is not the same, one is CCS, one is CCS2. CCS is a combination of AC and DC made together. But when charging, there will only be one, either AC so DC.

The charging systems of Europe and the Americas have certain differences in the AC part, but the use protocol and control logic of the DC part are the same. It is also worth mentioning the Japanese CHAdeMO standard, in fact, the Japanese standard is the world's first DC charging system, which was launched after 2009.

There is also China's GBT standard, the GBT standard is the first version of 2011, just mentioned in europe and the United States CCS is actually more backward, almost in 2012, 13 years when it landed. Although these standards are different, the interface is not the same, but their purpose is the same, there is no fundamental difference in demand, are to supplement the battery energy, plug and charge, these are no different in the world.

After several years of development, the country is expected to launch the ChaoJi interface for standardization, and in order to achieve compatibility, we have made some special designs on the guide circuit, which can identify whether the charging pile is new or old through some matches on these circuits, and then make corresponding compatibility adjustments, in this way to achieve the compatibility problem of the transition period.

05

Increased endurance, increased current or voltage

Worldwide, generally speaking, the first step in increasing power is to increase the current, and then to increase the voltage.

The heat generation problem caused by the increase in current is nothing more than two major solutions, one increases the cross-sectional area of the conductor and makes the resistance smaller. This is the most conventional method of use, that is, it is getting thicker and thicker, and now the charging cable users can't move, the wire has become particularly hard, and charging is very inconvenient. The other is to use cold liquid, but the leakage problem will directly lead to the explosion, which is also very worth focusing on.

After increasing the voltage, the current can be smaller to reduce the heat generation, but increasing the voltage will bring safety problems. Due to the outsourcing of parts, the whole system does not work well together. As the voltage rises, its safety problems will become more and more prominent. At the same time, increasing the voltage will increase the requirements of the parts a lot, so this thing needs some compromise solutions, not all cars need a high voltage platform.

For high-temperature cooling, there are two main choices, generally speaking, this is two directions, one is that the efficiency of the coolant is higher, but it may not be insulated, and there is a material that uses some insulation, but its thermal efficiency will be lower, but its safety may be slightly higher.

There may be some manufacturers in both directions in use, and now foreign countries use this ordinary liquid-cooled way to do it, and the domestic may be a little more of the latter. Now it may be because from the perspective of the whole world, although everyone is doing this, but there is no large-scale use, so which technology is final in the future, it should not be very certain now.

Source of this article: See Wisdom Research Pro, Author: Han Feng