How is your pure electric vehicle experience?
Discounted battery life may not be the worst thing. Recently, more than a dozen Canadian Tesla owners have reported that they can't even use the air conditioner in winter, not only the car's battery life is discounted because of the cold, but people's noses and tears are also frozen.
Moreover, these are basically heat pump air conditioners that cannot be heated in winter.
This is very strange. The high-efficiency and power-saving advantages of heat pump air conditioners have not been brought into play, but they cannot be heated, which has attracted the doubts of some car owners in Canada, and also attracted the attention of the Tesla R&D team. Musk has said that this is a high priority for Tesla to solve.
But even more bizarrely, Musk said the failure of the heat pump air conditioner turned out to be a software issue that could be done with a firmware update. Perhaps many people have never heard of it, air conditioners also need OTA. However, after understanding the structure and working principle of the Tesla heat pump air conditioner, you can find that this set of hardware can realize 12 different functions, and the realization of all functions relies on software control.
So, the Tesla heat pump air conditioner problem may really be a software problem.
So, how amazing is Tesla's heat pump air conditioner? Why is it impossible to cool under extremely cold conditions, and can the industry solve this problem? After reading Tesla's heat pump air conditioner patent and having a conversation with Midea Welling engineers, the car thing found the answer to the question.
01. Canadian car owner's heat pump failure can be solved by firmware update
This month, countries in the northern hemisphere ushered in the coldest time since winter, and electric vehicles have also entered the worst stage of the year.
Recently, some Canadian Tesla owners reported that they were driving in extremely cold conditions, and the heat pump air conditioner could not be used.
Twitter user @TSelvig said the temperature had dropped to -40°C when he traveled that day. In this extremely cold weather, when he drove the Tesla Model Y, the heat pump air conditioner did not work. After trying to restart the vehicle, calling Tesla customer service, the problem still can't be solved, and the owner is also a few hours' drives from the nearest service center, and it is impossible to drive without air conditioning.
In the end, the family switched to fuel vehicles for travel.
Another Model Y owner, @paateach, has a richer experience. His Model Y has been without warm air for two consecutive winters.
He said in a tweet that he lived in Saskatchewan, southern Canada, and encountered a situation where the heat pump air conditioner was unavailable in February last year, and there was no warm air for a whole month. Later, Tesla replaced a set of supermanifolds for him, and the heat pump air conditioner could be used at that time. However, by this winter, when the temperature dropped to -30°C, he again encountered the situation that the heat pump air conditioner could not be used.
At that time, he photographed the prompt on the car's screen: the cockpit climate control system needs to be repaired, and the heating and cooling systems will be limited or unavailable.
Two car 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 this winter, they hope to sell their Teslas and return to fuel cars, at least there will be no air conditioning and heating failures.
Angie Dean, chairman of the Tesla Owner's Club in Alberta, Canada, said: "In Alberta and Saskatchewan, more than ten Tesla owners have experienced heat pump air conditioner failures. the problem of use."
Just last week, the car owner community Drive Tesla Canada tweeted @Musk asking him to comment on the heat pump issue, and Musk responded to the tweet within 5 minutes, saying repairing the heat pump air conditioner was a very high priority. 40 minutes later, Musk said the new firmware for heat pump air conditioners had been rolled out to users.
It is quite curious why the faulty heat pump air conditioner can be fixed by a firmware update? In addition, after the firmware update is completed, there are still car owners who report that the heating cannot be performed. Is the firmware update useful?
02. It is necessary to preheat the battery heat pump in advance for extremely cold travel. There may be hardware defects in the heat pump.
In a patent document published by Tesla in 2019, the structure and operation of the heat pump air conditioning system are shown. In early 2020, with the mass production of the Model Y, this patent was also translated into mass production applications for Tesla.
If you open the Tesla's front trunk, you can see the heat pump air conditioner multiple pipes, and wiring harnesses. In fact, this is just the "tip of the iceberg" of the heat pump system. From the patent map, Tesla's heat pump air conditioner has 11 main components and is responsible for the thermal cycle of the entire vehicle, which can lead to different parts of the vehicle such as the cockpit, battery pack, and motor.
These main components are compressor, cabin condenser, cabin evaporator, battery system cooling unit, cabin blower, electric motor liquid-cooled condenser, battery, three-way compressor outlet, low voltage electric cabin heater (PTC), recirculating air conditioner, Heating.
Among the 11 main components, Tesla did not directly cancel the traditional PTC heating, but still equipped a low-pressure PTC heating. However, due to insufficient power, this PTC heating unit does not directly heat the cabin but provides auxiliary heating when the heat pump system is insufficient.
What is more surprising is that Tesla's hardware can implement 12 different working modes, which are completed through different software scheduling.
Among these 12 working modes, there are not many modes involved in the heat pump, only three. Heat pump participation in heating can be divided into pure heat pump mode and hybrid heating mode. When the heat pump efficiency is high, the pure heat pump mode is enabled, and when the efficiency is low, the hybrid heating mode is enabled. The heat pump can be mixed with PTC heating, and can also be added to the evaporator to heat together.
In addition, simply using the compressor and evaporator can also heat the cabin and the battery system. In addition, the in-vehicle thermal circulation system can also realize functions such as cockpit defogging, defrosting, and dehumidification.
A conclusion can be drawn here: it is indeed feasible to fix the problem of the heat pump air conditioner through a firmware update.
When there is no problem with the hardware of the heat pump air conditioning system, adjusting the software scheduling in different environments can realize the adjustment of the heat pump air conditioning system.
For heat pump systems alone, there is a strong correlation between the efficiency of heating the cabin and the efficiency of the heat pump. Because the working principle of heat pump air conditioner is to exchange thermal energy inside and outside the car.
Through the evaporator, the refrigerant can absorb heat from the external environment, and after the refrigerant in the vehicle is liquefied, it releases heat, which can be used to heat the cabin.
However, if the temperature of the outside environment is lower, it will be more difficult for the refrigerant to obtain heat from the outside environment, which leads to the low heating efficiency of the heat pump air conditioner in the extremely cold environment.
Tesla is aware of this obvious problem and has added auxiliary heating in addition to the heat pump air conditioner.
Tesla has drawn a chart in the patent that can explain the efficiency of heat pump air conditioners under different temperature conditions. The efficiency coefficient of the heat pump air conditioner is represented by COP (Coefficient of Performance). When COP=1, it means that the power consumption and the heat energy generated are equal; when COP>1, the heat pump air conditioner is in the high-efficiency area, which means that less power consumption can be obtained. much thermal energy.
As can be seen from Tesla's chart, when the ambient temperature and the battery temperature are lower than -20°C at the same time, the efficiency of the heat pump air conditioner will be very low. This temperature is also considered by Tesla to be an extremely cold temperature. At this temperature, there is no solution below. But at this time, only need to heat the battery, 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 and relies on evaporation to achieve heating. When COP ≥ 1, the heat pump air conditioner will participate in heating, and the temperature needs to be above -10 °C.
The second conclusion can be drawn here: if the outside weather is extremely cold, even if the firmware of the heat pump air conditioner is updated, the heating effect will still be poor. The solution is to heat the battery, or rather preheat the battery before you travel.
However, under Musk’s reply to the tweet that the firmware has been updated, there are still many users who report that the vehicle still cannot be heated.
Well, there's a good chance that there's a hardware problem.
Tesla owner @paateach tweeted that his Tesla Model Y has had two super-manifolds replaced, which include heat pump air conditioning sensors, expansion valves, and refrigerant lines. The heating system works temporarily, but I am very worried that it may be damaged again.
Twitter user Tesla owner revealed the development story of the heat pump air conditioner online. Recently, Tesla's engineers in California and Alaska have been testing heat pump air conditioners. The test results found that Tesla's heat pump air conditioners can work normally when the temperature is lower than -30 °C. The reason is that the heat pump air conditioner has two refrigerants.
At the same time, engineers also found a problem: in extremely cold weather, the front air intake cover will be frozen, causing cold air to be sucked in during driving. Because the cold air temperature is too low, the sensor will report an error to the system after sensing, and 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 heating failure in extremely cold weather. But to completely solve this problem, Tesla may need to update some hardware in the later stage.
03. Hybrid heating can deal with low temperature Some companies are still exploring new refrigerants
For the automotive industry, heat pump air conditioners are still a new thing, and Tesla Model Y will be mass-produced in early 2020. Prior to this, pure electric vehicles generally used the PTC method to heat the interior of the vehicle. But even under ideal conditions, the COP of PTC is 1. The low efficiency leads to very large power consumption of PTC heating, which in turn becomes a major factor affecting the battery life of electric vehicles in winter.
The high-efficiency performance of heat pump air conditioners has attracted the attention of electric vehicle companies. The pure electric vehicles newly launched in 2021 will basically be upgraded from the previous PTC heating to heat pump air conditioners. However, due to the limitation of refrigerants, the efficiency of the heat pump will be greatly reduced when the temperature is usually lower than -10°C. At this time, it is necessary to rely on PTC heating to heat the vehicle.
For example, Xiaopeng P5 is equipped with a heat pump air conditioner to achieve efficient heating, but it is also equipped with PTC. When the temperature is lower than -10°C, the vehicle will activate PTC heating to heat the interior of the car.
It can be said that Xiaopeng P5 solves the shortcomings of heat pump air conditioners to a certain extent, but it has not been completely solved.
Another new auto parts manufacturer, Welling, solved the heating problem in extremely cold weather. Speaking of Welling, many friends in the automotive circle are probably not unfamiliar. Welling is a subsidiary of Midea Group, a leading domestic home appliance company.
Last year, Welling announced several auto parts that were put into production, including automotive heat pump air conditioners.
At present, the refrigerant commonly used in heat pump air conditioners is R134a (CH 2 FCF 3, tetrafluoroethane), but when the outside temperature is low, the heat attenuation is very obvious. Therefore, there is an exploration of mixed refrigerants in the industry, but there is no obvious performance improvement.
Engineers of Welling Components took a different approach and used carbon dioxide as the refrigerant, which significantly improved the heating efficiency at extremely cold temperatures.
Welling's rotary CO 2 electric compressor can achieve a heating efficiency of COP=2 at -30°C. At the same time, the noise during its operation is low, and the overall design is lighter.
According to Welling engineers, in extremely cold weather, users do not need to "cover the quilt" to drive. At the same time, compared with traditional heat pump air conditioners, the heat pump with carbon dioxide as the refrigerant can increase the cruising range of the vehicle by up to 20%.
Only CO 2 electric compressors have 220 domestic invention patents and 14 international invention patents and have completely independent intellectual property rights. At the same time, CO 2 , as a common greenhouse gas, is collected and used as a refrigerant, which also contributes to "carbon neutrality".
Last year, the heat pump air-conditioning products of Midea Group's Welling Components have been installed on pure electric brand models such as Xiaopeng and Weilai, becoming a microcosm of the rapid transformation of domestic component companies to electrification.
04. Conclusion: There is still huge room for innovation in electric vehicles
In 2020, Tesla will install heat pump air conditioners into pure electric vehicles, driving the electric vehicle industry one step further in the direction of high efficiency. In just one year, by 2021, heat pump air conditioning has become standard in high-end electric vehicles.
Obviously, technologies that will not be used in the era of fuel vehicles may be huge innovations in the era of electric vehicles. In today's increasingly fierce global electric vehicle competition, there is still huge room for innovation in the field of electric vehicles.
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