Compressor control method and system for electric vehicle

Abstract

The present application relates to the technical field of vehicle control, in particular to a compressor control method and system of an electric vehicle. An A / C opening input signal is received; the compressor speed is gradually increased from 0 to a working speed; the coolant temperature is monitored in real time; if the coolant temperature does not exceed a preset first coolant temperature threshold, the compressor speed is kept at the working speed; if the coolant temperature exceeds the preset first coolant temperature threshold, the compressor speed is controlled by a compressor speed reduction control method; during the process of controlling the compressor speed by the compressor speed reduction control method, the motor power is normally output, and the preset first coolant temperature threshold is less than the trigger threshold of the motor protection logic of the vehicle controller. The coolant temperature is prevented from exceeding the limit value, thereby avoiding the limitation of the motor power output, and the problem of vehicle unable to normally drive is solved.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, and specifically to a compressor control method and system for electric vehicles. Background Technology

[0002] Electric vehicles (EVs) have become one of the mainstream directions for the future development of the automotive industry due to their advantages such as zero emissions, high energy efficiency, and low noise pollution. However, the optimal design for matching thermal management control strategies between the powertrain and passenger compartment is particularly important. Meanwhile, considering reducing wind resistance and increasing vehicle range, a closed main air intake grille has become a key feature distinguishing pure electric vehicles from traditional gasoline vehicles, which significantly increases the difficulty of thermal management in the front engine compartment. Currently, although scholars and companies both domestically and internationally have conducted extensive research on the thermal management systems of electric vehicles, problems remain, including simplistic configurations, limited functionality, insufficient performance optimization, and a lack of comprehensive evaluation studies.

[0003] Especially in recent years, with summer temperatures higher than in previous years, the temperature inside the power compartment has also been higher than in previous years. When a small pure electric vehicle is idling, the temperature inside the power compartment (coolant temperature) exceeds the maximum temperature threshold, triggering the EVC (vehicle controller) motor protection logic, and the motor power output is limited.

[0004] like Figure 1 As shown, the existing compressor control method is as follows:

[0005] Upon receiving the A / C start input signal, the compressor is gradually increased to the operating speed via the LIN signal;

[0006] The coolant temperature is monitored in real time. If the coolant temperature exceeds the threshold, the compressor speed is maintained at the operating speed, and the motor power output is limited.

[0007] This control method, by limiting the motor's power output, can prevent the vehicle from operating normally and, in severe cases, pose a fire risk. Therefore, a reasonable thermal management control strategy is more beneficial for the operation of electric vehicles and avoids the risk of fire. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing a compressor control method and system for electric vehicles, which prevents the coolant temperature from exceeding the limit, thereby preventing the motor power output from being limited and solving the problem of the vehicle being unable to drive normally.

[0009] The present invention discloses a compressor control method for an electric vehicle, comprising the following steps:

[0010] Receive the A / C input activation signal;

[0011] Control the compressor speed to gradually increase from 0 to the operating speed;

[0012] The coolant temperature is monitored in real time. If the coolant temperature does not exceed the preset first coolant temperature threshold, the compressor speed is maintained at the operating speed. If the coolant temperature exceeds the preset first coolant temperature threshold, the compressor speed is reduced by a compressor speed reduction control method.

[0013] During the process of reducing the speed of the compressor by means of the compressor speed reduction control method, the motor power is output normally, and the preset first coolant temperature threshold is less than the trigger threshold of the motor protection logic of the vehicle controller.

[0014] Preferably, the method of controlling the compressor speed reduction by the compressor speed reduction control method includes:

[0015] Reduce the compressor speed from the operating speed to the preset speed;

[0016] If the coolant temperature is lower than the second coolant temperature threshold, the compressor speed is maintained at the preset speed.

[0017] If the coolant temperature is not lower than the second coolant temperature threshold, then the compressor speed is reduced to 0.

[0018] The first coolant temperature threshold is less than the second coolant temperature threshold, and the preset rotation speed is less than the operating rotation speed.

[0019] More preferably, after reducing the compressor speed to 0, the method further includes:

[0020] The temperature of the coolant is determined;

[0021] If the first coolant temperature threshold is less than the coolant temperature and the second coolant temperature threshold, then the compressor speed will be increased from 0 to the preset speed.

[0022] If the coolant temperature is less than or equal to the first coolant temperature threshold, the compressor speed will be gradually increased from 0 to the operating speed.

[0023] If the coolant temperature is greater than or equal to the second coolant temperature threshold, then the compressor speed is maintained at 0.

[0024] Preferably, the preset speed is the lowest speed selected based on the compressor characteristic curve.

[0025] Preferably, the first coolant temperature threshold is obtained based on empirical data.

[0026] Preferably, the preset rotation speed is 2000 rpm.

[0027] Preferably, the temperature threshold of the first coolant is 57-60°C.

[0028] Preferably, the coolant temperature is obtained by reading the internal coolant temperature of the electric drive cooling system from the vehicle's EVC (Electric Vehicle Control) system.

[0029] The present invention also provides a compressor control system for electric vehicles, comprising:

[0030] The receiving module is used to receive the A / C input signal to enable.

[0031] The judgment module is used to monitor the coolant temperature in real time and compare the coolant temperature with a preset first coolant temperature threshold.

[0032] The control module is used to control the compressor speed based on the comparison results, including...

[0033] If the coolant temperature does not exceed the preset first coolant temperature threshold, the compressor speed is maintained at the operating speed; if the coolant temperature exceeds the preset first coolant temperature threshold, the compressor speed is reduced by a compressor speed reduction control method.

[0034] During the process of reducing the speed of the compressor by means of the compressor speed reduction control method, the motor power is output normally, and the preset first coolant temperature threshold is less than the trigger threshold of the motor protection logic of the vehicle controller.

[0035] Preferably, the control module further includes:

[0036] Reduce the compressor speed from the operating speed to the preset speed;

[0037] If the coolant temperature is lower than the second coolant temperature threshold, the compressor speed is maintained at the preset speed.

[0038] If the coolant temperature is not lower than the second coolant temperature threshold, then the compressor speed is reduced to 0.

[0039] The first coolant temperature threshold is less than the second coolant temperature threshold, and the preset rotation speed is less than the operating rotation speed;

[0040] After reducing the compressor speed to 0, the method further includes:

[0041] The temperature of the coolant is determined;

[0042] If the first coolant temperature threshold is less than the coolant temperature and the second coolant temperature threshold, then the compressor speed will be increased from 0 to the preset speed.

[0043] If the coolant temperature is less than or equal to the first coolant temperature threshold, the compressor speed will be gradually increased from 0 to the operating speed.

[0044] If the coolant temperature is greater than or equal to the second coolant temperature threshold, then the compressor speed is maintained at 0.

[0045] The beneficial effects of this invention are as follows:

[0046] 1. This method addresses the problem of vehicles malfunctioning due to excessively high coolant temperature in the engine compartment during hot summer months, which limits motor power output. It involves analyzing the heat sources in the engine compartment and optimizing the thermal management matching between the engine compartment and the passenger compartment. By proactively controlling the rise in coolant temperature, a first coolant temperature threshold is set before the motor protection logic triggers on the vehicle controller. When the coolant temperature exceeds this threshold, the compressor speed is reduced using a speed reduction control method, while the motor power output remains normal throughout the entire control process. This method prevents the coolant temperature from exceeding the limit, thus avoiding motor power limitation and resolving the vehicle malfunction issue.

[0047] 2. The compressor speed reduction control method intervenes in advance to control the rising water temperature trend. A secondary threshold is set before the highest water temperature threshold to further slow down the temperature rise. Specifically, the compressor speed is reduced from the operating speed to a preset speed; if the coolant temperature is lower than the second coolant temperature threshold, the compressor speed is maintained at the preset speed; if the coolant temperature is not lower than the second coolant temperature threshold, the compressor speed is reduced to 0. After reducing the compressor speed to 0, the coolant temperature is assessed. If the first coolant temperature threshold < coolant temperature < second coolant temperature threshold, the compressor speed is increased from 0 to the preset speed; if the coolant temperature ≤ the first coolant temperature threshold, the compressor speed is gradually increased from 0 to the operating speed; if the coolant temperature ≥ the second coolant temperature threshold, the compressor speed is maintained at 0. Through the setting and assessment of the first and second coolant temperature thresholds, the compressor is shut down or operates at a suitable low / operating speed, thereby minimizing the rise in coolant temperature and preventing the motor power from being limited, thus solving the problem of the vehicle being unable to drive normally. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the existing compressor control process;

[0049] Figure 2 This is a schematic diagram of the compressor control method of the present invention;

[0050] Figure 3 This is a schematic diagram of the compressor's characteristic curves;

[0051] Figure 4 This is a simulation diagram of vehicle speed under the existing compressor control method;

[0052] Figure 5This is a simulation diagram of vehicle speed under the compressor control method of the present invention;

[0053] Figure 6 Temperature cloud map of the engine compartment before improvement;

[0054] Figure 7 This is the improved engine compartment temperature cloud map based on this method;

[0055] Figure 8 The image shows the vehicle speed curve before the improvement.

[0056] Figure 9 This is the improved car speed curve. Detailed Implementation

[0057] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0058] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0059] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0060] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0061] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0062] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" means "two or more."

[0063] Example 1

[0064] Figure 2 A preferred embodiment of this application is shown. Figure 1 A flowchart illustrating a compressor control method for an electric vehicle according to the first embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0065] The present invention discloses a compressor control method for an electric vehicle, comprising the following steps:

[0066] Receive the A / C input activation signal;

[0067] Control the compressor speed to gradually increase from 0 to the operating speed;

[0068] The coolant temperature is monitored in real time. If the coolant temperature does not exceed the preset first coolant temperature threshold, the compressor speed is maintained at the operating speed. If the coolant temperature exceeds the preset first coolant temperature threshold, the compressor speed is reduced by a compressor speed reduction control method.

[0069] During the process of reducing the speed of the compressor by means of the compressor speed reduction control method, the motor power is output normally, and the preset first coolant temperature threshold is less than the trigger threshold of the motor protection logic of the vehicle controller.

[0070] In one embodiment, the method of controlling the compressor speed reduction by the compressor speed reduction control method includes:

[0071] Reduce the compressor speed from the operating speed to the preset speed;

[0072] If the coolant temperature is lower than the second coolant temperature threshold, the compressor speed is maintained at the preset speed.

[0073] If the coolant temperature is not lower than the second coolant temperature threshold, then the compressor speed is reduced to 0.

[0074] The first coolant temperature threshold is less than the second coolant temperature threshold, and the preset rotation speed is less than the operating rotation speed.

[0075] In one embodiment, after reducing the compressor speed to 0, the method further includes:

[0076] The temperature of the coolant is determined;

[0077] If the first coolant temperature threshold is less than the coolant temperature and the second coolant temperature threshold, then the compressor speed will be increased from 0 to the preset speed.

[0078] If the coolant temperature is less than or equal to the first coolant temperature threshold, the compressor speed will be gradually increased from 0 to the operating speed.

[0079] If the coolant temperature is greater than or equal to the second coolant temperature threshold, then the compressor speed is maintained at 0.

[0080] In one embodiment, according to such Figure 3 The compressor characteristic curves shown indicate that the lowest speed was selected as the intermediate state, balancing passenger compartment cooling with minimal condenser heat dissipation, thus reducing the tendency for water temperature to rise. The optimal speed for the electric scroll compressor was ultimately determined to be 2000 rpm.

[0081] In one embodiment, the first coolant temperature threshold is obtained based on empirical data.

[0082] In one embodiment, the first coolant temperature threshold is 57-60°C, and in this embodiment, it is preferably 59°C.

[0083] In one embodiment, the coolant temperature is obtained by reading the coolant temperature inside the electric drive cooling system from the compressor's internal controller, or by reading the coolant temperature inside the electric drive cooling system from the vehicle's EVC (Electronic Vehicle Temperature Controller). Since EVC software verification has the lowest cost, this embodiment selects reading the coolant temperature inside the electric drive cooling system from the vehicle's EVC.

[0084] Example 2

[0085] This embodiment also provides a compressor control system for a motor vehicle, including:

[0086] The receiving module is used to receive the A / C input signal to enable.

[0087] The judgment module is used to monitor the coolant temperature in real time and compare the coolant temperature with a preset first coolant temperature threshold.

[0088] The control module is used to control the compressor speed based on the comparison results, including...

[0089] If the coolant temperature does not exceed the preset first coolant temperature threshold, the compressor speed is maintained at the operating speed; if the coolant temperature exceeds the preset first coolant temperature threshold, the compressor speed is reduced by a compressor speed reduction control method.

[0090] During the process of reducing the speed of the compressor by means of the compressor speed reduction control method, the motor power is output normally, and the preset first coolant temperature threshold is less than the trigger threshold of the motor protection logic of the vehicle controller.

[0091] Preferably, the control module further includes:

[0092] Reduce the compressor speed from the operating speed to the preset speed;

[0093] If the coolant temperature is lower than the second coolant temperature threshold, the compressor speed is maintained at the preset speed.

[0094] If the coolant temperature is not lower than the second coolant temperature threshold, then the compressor speed is reduced to 0.

[0095] The first coolant temperature threshold is less than the second coolant temperature threshold, and the preset rotation speed is less than the operating rotation speed;

[0096] After reducing the compressor speed to 0, the method further includes:

[0097] The temperature of the coolant is determined;

[0098] If the first coolant temperature threshold is less than the coolant temperature and the second coolant temperature threshold, then the compressor speed will be increased from 0 to the preset speed.

[0099] If the coolant temperature is less than or equal to the first coolant temperature threshold, the compressor speed will be gradually increased from 0 to the operating speed.

[0100] If the coolant temperature is greater than or equal to the second coolant temperature threshold, then the compressor speed is maintained at 0.

[0101] The actual vehicle was placed in an environmental chamber to conduct thermal management experiments and verifications. Standard procedures were followed, and additional conditions were added to conduct relevant tests (ambient temperature 45℃, tests were conducted at idle and high speeds). A laboratory environmental simulation system was used to model the harsh high-temperature and high-sunlight environments encountered in actual vehicle use. A front-mounted blower simulated the airflow on the vehicle's frontal surface during driving, and a rotating test bench simulated high-speed conditions. A signal acquisition system monitored the temperature and other relevant information of each thermal management system within the vehicle during the actual process.

[0102] The thermal management signal acquisition in the powertrain compartment mainly involves sensor placement at measurement points on the surfaces of components, with temperature sensors measuring the surface temperature of the main powertrain components. The vehicle's DDT signal line collects data such as coolant temperature, compressor speed, and vehicle speed. The thermal management signal acquisition in the passenger compartment mainly involves sensor placement at measurement points at the air vents and front vents, with temperature sensors measuring the key temperatures in the passenger compartment. Based on the vehicle's high-temperature motor power-limiting ring model verification conditions, data was collected and read from relevant test points under both idle and high-speed conditions.

[0103] Based on the above tests, it can be concluded that the high temperature at the fan outlet is caused by the backflow of high temperature emitted from the surface of the condenser in the engine compartment, which poses a fire risk in harsh environments.

[0104] Based on the presence of headwinds during actual driving, the coolant temperature drops significantly after the vehicle is started, while the temperature inside the passenger compartment does not rise noticeably, as detailed below:

[0105] Under idling conditions, the optimized coolant temperature is 7°C lower than the unoptimized temperature, while the optimized passenger compartment temperature is slightly higher than the unoptimized temperature.

[0106] Under high-speed conditions, the temperature difference between the coolant and the passenger compartment is small before and after optimization, because the oncoming wind can carry away most of the heat load.

[0107] Before optimization, such as Figure 4 After the vehicle starts, the coolant temperature in the motor cooling system rises to 64℃, triggering the temperature limiting logic. The 'power limit' light illuminates, causing the vehicle to malfunction and preventing it from moving normally (acceleration performance decreases, specific speed is as follows). Figure 8 ).

[0108] After optimization, such as Figure 5 As mentioned above, due to the adoption of variable frequency control technology, when the system temperature approaches the critical value of 59℃, the system heat load is effectively reduced through active frequency conversion (coolant temperature is positively correlated with compressor speed, i.e., the coolant temperature decreases accordingly when the compressor speed decreases). After matching and calibration, the compressor speed is maintained at 2000rpm for an average of 6 minutes. However, this duration is too long (stage 1.2), and the temperature inside the passenger compartment rises, resulting in a poor subjective experience. Therefore, the system is further optimized (the time period of temperature rise in the vehicle interior shown in the above figure represents this process): the water temperature threshold for the compressor speed to recover from 2000rpm to 4300rpm is adjusted from 58℃ to 59℃ to improve the environmental comfort of the passenger compartment.

[0109] Furthermore, after optimization, the cooling system temperature remained below 64℃ throughout the entire experiment, preventing the temperature limiting logic from being triggered, and the passenger cabin temperature comfort remained significantly unchanged. No 'power limit' alarms were triggered during the experiment, and the vehicle could operate normally.

[0110] like Figure 6 ,7 It can be seen that the temperature of the engine compartment is lower after optimization than before optimization.

[0111] like Figure 8 , 9 The data used in the experiment were vehicle speed data. Since the 0-41 km / h range is the subjective evaluation stage of the air conditioning after starting, there are differences in the accelerator pedal control before and after optimization. Therefore, the acceleration time was compared during the period of consistent vehicle speed control, which is 43-95 km / h.

[0112] like Figure 8 As shown, the coolant temperature in the motor cooling system rises to 64℃, triggering the temperature limiting logic. The 'power limit' light illuminates, and the power output of the powertrain is limited. The vehicle takes 75 seconds to accelerate from 42km / h to 95km / h, and the vehicle cannot drive normally.

[0113] like Figure 9 As shown, there was no 'power limit' alarm during the entire experiment, the powertrain output power was unlimited, the vehicle accelerated from 42km / h to 95km / h in 15 seconds, and the vehicle could drive normally.

[0114] (Based on the experimental conditions, the coolant cooling needs to be observed at 40±3km / h. There is a difference in the holding time at 40±3km / h before and after optimization, so only the acceleration of the car from 42km / h to 95km / h is compared.)

[0115] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0116] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0117] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0118] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as it is used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0119] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A compressor control method for an electric vehicle, characterized in that, Includes the following steps: Receive the A / C input activation signal; Control the compressor speed to gradually increase from 0 to the operating speed; The coolant temperature is monitored in real time. If the coolant temperature does not exceed the preset first coolant temperature threshold, the compressor speed is maintained at the operating speed. If the coolant temperature exceeds the preset first coolant temperature threshold, the compressor speed is reduced by a compressor speed reduction control method. During the process of reducing the speed of the compressor by the compressor speed reduction control method, the motor power is output normally, and the preset first coolant temperature threshold is less than the trigger threshold of the motor protection logic of the vehicle controller. The method of controlling the compressor speed reduction includes: Reduce the compressor speed from the operating speed to the preset speed; If the coolant temperature is lower than the second coolant temperature threshold, the compressor speed is maintained at the preset speed. If the coolant temperature is not lower than the second coolant temperature threshold, then the compressor speed is reduced to 0. The first coolant temperature threshold is less than the second coolant temperature threshold, and the preset rotation speed is less than the operating rotation speed; After reducing the compressor speed to 0, the method further includes: The temperature of the coolant is determined; If the first coolant temperature threshold is less than the coolant temperature and the second coolant temperature threshold, then the compressor speed will be increased from 0 to the preset speed. If the coolant temperature is less than or equal to the first coolant temperature threshold, the compressor speed will be gradually increased from 0 to the operating speed. If the coolant temperature is greater than or equal to the second coolant temperature threshold, then the compressor speed is maintained at 0.

2. The compressor control method for electric vehicles according to claim 1, characterized in that: The preset speed is the lowest speed selected based on the compressor characteristic curve.

3. The compressor control method for electric vehicles according to claim 1, characterized in that: The first coolant temperature threshold is obtained based on empirical data.

4. The compressor control method for electric vehicles according to claim 1, characterized in that: The preset rotation speed is 2000 rpm.

5. The compressor control method for an electric vehicle according to claim 1, characterized in that: The first coolant temperature threshold is 57~60℃.

6. The compressor control method for an electric vehicle according to claim 1, characterized in that: The coolant temperature is obtained by reading the internal coolant temperature of the electric drive cooling system from the vehicle's EVC (Electric Vehicle Control) system.

7. A compressor control system for a motor vehicle, characterized in that, include: The receiving module is used to receive the A / C input signal to enable. The judgment module is used to monitor the coolant temperature in real time and compare the coolant temperature with a preset first coolant temperature threshold. The control module is used to control the compressor speed based on the comparison results, including... If the coolant temperature does not exceed the preset first coolant temperature threshold, the compressor speed is maintained at the operating speed; if the coolant temperature exceeds the preset first coolant temperature threshold, the compressor speed is reduced by a compressor speed reduction control method. During the process of reducing the speed of the compressor by the compressor speed reduction control method, the motor power is output normally, and the preset first coolant temperature threshold is less than the trigger threshold of the motor protection logic of the vehicle controller. The control module also includes: Reduce the compressor speed from the operating speed to the preset speed; If the coolant temperature is lower than the second coolant temperature threshold, the compressor speed is maintained at the preset speed. If the coolant temperature is not lower than the second coolant temperature threshold, then the compressor speed is reduced to 0. The first coolant temperature threshold is less than the second coolant temperature threshold, and the preset rotation speed is less than the operating rotation speed; After reducing the compressor speed to 0, the method further includes: The temperature of the coolant is determined; If the first coolant temperature threshold is less than the coolant temperature and the second coolant temperature threshold, then the compressor speed will be increased from 0 to the preset speed. If the coolant temperature is less than or equal to the first coolant temperature threshold, the compressor speed will be gradually increased from 0 to the operating speed. If the coolant temperature is greater than or equal to the second coolant temperature threshold, then the compressor speed is maintained at 0.

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