Car stuff (public number: chedongxi)
The author | James
Edit the | Xiao Han
Counting nine cold winters, how is your pure electric vehicle experience?
Battery life discounts may not be the worst thing to do. Recently, there have been more than a dozen Canadian Tesla owners feedback that even air conditioning can not be used in winter, not only the car is frozen to a discount, people are frozen to a snot and a handful of tears.
Moreover, the basic heat pump air conditioners that cannot be heated in these winters are heat pumps.
This is very strange, the high efficiency and power saving advantages of heat pump air conditioning have not been played out, but can not be heated, which has attracted the questioning of some Car owners in Canada and has also attracted the attention of Tesla's research and development team. Musk has said that this is a high-priority problem for Tesla to solve.
But what's even stranger is that Musk said that the failure of the heat pump air conditioner turned out to be a software problem that could be done through a firmware update. Perhaps many people have never heard of it, and air conditioning also needs OTA. However, after understanding the structure and working principle of Tesla's heat pump air conditioner, it can be found that this set of hardware can achieve 12 different functions, and the implementation of all functions relies on software control.
Therefore, the problem of Tesla's heat pump air conditioner may really be a software problem.
So, how amazing is Tesla's heat pump air conditioner? Why is it that there is no cooling under extremely cold conditions, and can the industry solve this problem? After seeing Tesla's heat pump air conditioner patent and having a conversation with Midea Welling engineers, the car thing found the answer to the question.
First, the failure of the Heat Pump of the Canadian car owner can be solved by firmware update
This month, countries in the Northern Hemisphere saw their coldest time since winter, and electric cars entered the worst phase of the year.
Recently, there are Canadian Tesla owners who have reported that they are driving in an extremely cold environment, and the heat pump air conditioner cannot be used.
Twitter user @TSelvig said that by the time they traveled that day, the temperature had dropped to -40°C. In this extremely cold weather, when he drove the Tesla Model Y, the heat pump air conditioner could not be used. After trying to restart the vehicle and call Tesla customer service, the problem was still not solved, and the owner was also a few hours away from the nearest service center, and it was impossible to drive without air conditioning.
▲The user cannot work in the heat pump air conditioner in the -40 °C environment
Eventually, the family switched to a fuel vehicle.
Another Model Y owner, @paateach, has a more experience, and his Model Y has not had warm air for two consecutive winters.
▲ Some users have replaced the air conditioning parts and still fail
He tweeted that he lived in Saskatchewan, southern Canada, and had encountered a situation where the heat pump air conditioner was unusable last February, and there was no warm air for a whole month. Later, Tesla replaced him with a set of super manifolds, and the heat pump air conditioner was ready to use. However, by this winter, when the temperature dropped to -30 ° C, he again encountered a situation where the heat pump air conditioner could not be used.
At that time, he photographed the prompt on the screen of the car: the cockpit climate control system needs to be repaired, and the heating and cooling system will be limited or unusable.
▲The display on the car machine when the heat pump air conditioner fails
Two owners questioned Tesla: Why does Tesla's heat pump air conditioner fail in extremely cold weather? Tesla has been repaired several times, why is the repair plan still ineffective?
Some car owners even said that after experiencing this winter, they hope to sell their Teslas to return to fuel vehicles, at least there will be no air conditioning heating failures.
Angie Dean, president of Tesla Owner's Club in Alberta, Canada, said: "In Alberta and Saskatchewan, Canada, more than a dozen Tesla owners have had problems with heat pump air conditioners not working. ”
Musk said that he has updated the firmware to fix the problem
Just last week, the owner's community Drive Tesla Canada @ Musk on Twitter, asking him to comment on the heat pump problem, Musk replied to the tweet within 5 minutes, saying that repairing the heat pump air conditioner has a very high priority. 40 minutes later, Musk said that the new firmware for the heat pump air conditioner has been introduced to users.
It is quite curious, why can the faulty heat pump air conditioner be fixed through a firmware update? In addition, when the firmware update is completed, there are still car owners who feedback that they cannot heat up, is the firmware update useful in the end?
Second, extremely cold travel needs to preheat the battery in advance The heat pump may have hardware defects
In a patent document published by Tesla in 2019, it shows the structure and operation of the heat pump air conditioning system. In early 2020, with the mass production of the Model Y model, this patent was also translated into a mass production application for Tesla.
If you open Tesla's front load compartment, you can see the heat pump air conditioner and multiple pipes and wiring harnesses, which is actually just the "tip of the iceberg" of the heat pump system. From the patent diagram, Tesla's heat pump air conditioner has 11 main components, and is responsible for the heat cycle of the whole vehicle, which can lead to different parts of the vehicle such as cockpit, battery pack, and motor.
▲The position pointed by the arrow is Tesla heat pump air conditioner
These main components are compressors, cockpit condensers, cockpit evaporators, battery system coolers, cockpit blowers, motor liquid condensers, batteries, three-way compressor outlets, low-pressure electric cockpit heaters (PTC), recirculating air conditioning, and heating.
Of these 11 main components, Tesla did not directly eliminate the traditional PTC heating, but still equipped with a low-pressure PTC heating. However, due to insufficient power, this PTC heating device does not heat directly into the cockpit, but provides auxiliary heating when the heat pump system is underheated.
▲Tesla heat pump air conditioning system structure
What is more surprising is that Tesla's hardware can achieve 12 different working modes, which are scheduled through different software.
Of these 12 operating modes, the heat pump is not involved in many modes, only three. Heat pump participation in heating can be divided into pure heat pump mode and mixed heating mode. When the heat pump efficiency is high, the pure heat pump mode is enabled, and when the efficiency is low, the mixed heating mode is enabled, and the heat pump can be mixed with PTC heating, and the evaporator can be added to co-heat.
▲ 12 working modes and functions of Tesla heat pump air conditioner
In addition, the use of compressors and evaporators alone can also heat the cockpit and battery system. And the in-car thermal circulation system can also realize the functions of cockpit defogging, defrosting, dehumidification and so on.
Here we can draw a conclusion: the problem of heat pump air conditioning is indeed feasible to fix through firmware updates.
When there is no problem with the hardware of the heat pump air conditioning system, the adjustment of the software scheduling in different environments can realize the adjustment of the heat pump air conditioning system.
In terms of heat pump systems alone, there is a strong correlation between the efficiency of the heated cockpit and the efficiency of the heat pump. Because the working principle of heat pump air conditioning is to exchange heat energy inside and outside the car.
Through the evaporator, the refrigerant can absorb heat from the external environment, and after the refrigerant in the car is liquefied, the heat can be released, and the heat can be heated into the cockpit.
However, if the temperature of the external environment is lower, the more difficult it is for the refrigerant to obtain heat from the external environment, which leads to the heat pump air conditioner in an extremely cold environment.
Tesla is also aware of this obvious problem, so it has added auxiliary heating devices in addition to heat pump air conditioners.
Tesla drew a chart in the patent that could explain the efficiency of heat pump air conditioners under different temperature conditions. The efficiency coefficient of heat pump air conditioning is expressed in COP (Coefficient of Performance), when COP = 1, it means that the consumption of electrical energy and the heat energy generated are equal; when COP > 1, the heat pump air conditioner is in the high efficiency zone, which means that less power consumption can get more heat energy.
▲The influence of the ambient temperature and battery temperature in the car on the efficiency of the heat pump air conditioner
As can be seen from Tesla's chart, when the ambient temperature and battery temperature are below -20 ° C at the same time, the efficiency of the heat pump air conditioner will be very low, and this temperature is also considered by Tesla to be an extremely cold temperature, and there is no solution below this temperature. However, at this time, only the battery needs to be heated, the COP value will increase accordingly, and the heating system can be used normally.
When COP = 1, the heat pump air conditioner does not work, relying on evaporation to achieve heating, when the COP ≥ 1, the heat pump air conditioner will participate in heating, and the temperature needs to be above -10 ° C.
Here we can draw a second conclusion: if the weather outside is extremely cold, even if the heat pump air conditioning firmware is updated, the heating effect will still be poor. The solution is to heat the battery, or to preheat the battery before traveling.
However, under Musk's reply to the tweet that the firmware has been updated, many users have reported that the vehicle still cannot be heated.
Well, there's a good chance that there's a hardware issue with this.
Tesla owner @paateach said on Twitter that his Tesla Model Y has replaced the superhobe twice, including sensors for heat pump air conditioners, expansion valves and refrigerant lines. The heating system is temporarily available, but I am very worried that it may be damaged again.
▲The owner is still worried about damage again after replacing the parts twice
Twitter user Tesla owners online revealed the research and development story of heat pump air conditioners. Recently, Tesla engineers in California and Alaska are testing heat pump air conditioners, and the test results found that when it is below -30 ° C, Tesla's heat pump air conditioner can work normally, because the heat pump air conditioner has two refrigerant cycles.
▲ The owners' club said Tesla has found hardware problems
At the same time, engineers also found a problem: in extremely cold weather, the front air port cover will be frozen, resulting in cold air inhalation during driving. Because the cold air temperature is too low, the sensor will report an error to the system after sensing, at which point the compressor will stop working and the heating will stop.
In order to quickly solve this problem, Tesla may force the compressor to start through software, temporarily avoiding heat failure in extremely cold weather. But to solve this problem completely, Tesla may need to update some hardware in the later stage.
Third, mixed heating can cope with low temperatures Some companies are still exploring new refrigerants
For the automotive industry, heat pump air conditioning is still a new thing, and Tesla Model Y was only mass-produced in early 2020. Prior to this, pure electric vehicles generally used PTC methods to heat the interior of the car. But even under ideal conditions, PTC's COP is 1. The low efficiency leads to a very large power consumption of PTC heating, which in turn becomes a major factor affecting the winter battery life of electric vehicles.
The efficient performance of heat pump air conditioning has attracted the attention of electric vehicle companies, and the newly listed pure electric vehicles in 2021 have basically been upgraded from the previous PTC heating to heat pump air conditioning. However, due to the restrictions of refrigerant, the efficiency of the heat pump will be greatly reduced when the temperature is lower than -10 °C, and PTC heating must be relied on to heat the vehicle.
For example, the Xiaopeng P5 is equipped with a heat pump air conditioner to achieve efficient heating, but it is also equipped with PTC, and when the temperature is lower than -10 °C, the vehicle will be enabled to heat the interior.
It can be said that Xiaopeng P5 has solved the shortcomings of heat pump air conditioning to a certain extent, but it has not been completely solved.
Another new auto parts manufacturer, Welling, has solved the problem of heating in extremely cold weather. Speaking of Welling, many friends in the automotive circle may not be strangers, welling is a subsidiary of the Midea Group, the head of domestic home appliances.
Last year, Welling announced that it would put into production several auto parts, including automotive heat pump air conditioners.
At present, the refrigerant commonly used in heat pump air conditioning is R134a (CH2FCF3, tetrafluoroethane), but when the external temperature is low, the heat decay is very obvious. Therefore, there are mixed refrigerants in the industry, but there is no obvious performance improvement.
▲Midea Welling electric compressor
Engineers at Welling Parts have taken a different approach, using carbon dioxide as the refrigerant, which has significantly improved the heating efficiency in extremely cold temperatures.
Welling's rotary lobe CO2 electric compressors are capable of achieving a heating efficiency of COP=2 at -30°C. At the same time, the noise is low during operation and the overall design is lighter.
Welling engineers introduced that in extremely cold weather, users do not need to "cover the quilt" to drive, and compared with traditional heat pump air conditioning, carbon dioxide as a refrigerant heat pump, up to 20% of the vehicle's mileage can be increased.
Co2 electric compressor alone has 220 domestic invention patents, and 14 international invention patents, and has complete independent intellectual property rights. At the same time, CO2, as a common greenhouse gas, is collected as a refrigerant and also contributes to "carbon neutrality".
Last year, midea group welling parts heat pump air conditioning products have been installed in Xiaopeng, Weilai and other pure electric brand models, becoming a microcosm of the rapid transformation of domestic parts companies to electrification.
Conclusion: Electric vehicles still have a huge room for innovation
In 2020, Tesla installed heat pump air conditioning into pure electric vehicles, driving the electric vehicle industry to take another step in the direction of efficiency. In just one year, by 2021, heat pump air conditioning has become the standard for high-end electric vehicles.
Obviously, the technology that will not be used in the era of fuel vehicles may be a huge innovation in the era of electric vehicles. Today, when the competition for electric vehicles in the world is becoming more and more fierce, there is still huge room for innovation in the field of electric vehicles.