A fresh air ratio control method for electric vehicle air conditioning system

Abstract

The present invention discloses a method for controlling the fresh air ratio of an electric vehicle air conditioning system. The method includes the following steps: When the air conditioning system starts, the ventilation system operates in a full internal circulation mode, and the CO2 concentration in the vehicle is monitored during operation. When the air conditioning system is in cooling mode, the ventilation ratio is calculated based on the CO2 concentration, and the ventilation mode is switched based on the ventilation ratio, and the fresh air ratio of the air conditioning system is adjusted. When the air conditioning system is in heating mode, the ventilation ratio is calculated based on the CO2 concentration and the constraint of glass fogging, and the ventilation mode is switched based on the ventilation ratio, and the fresh air ratio of the air conditioning system is adjusted. The method can intelligently adjust the fresh air ratio, minimizing the negative impact of the introduction of fresh air on the energy consumption of the air conditioning system.

Description

Technical Field

[0001] The present invention belongs to the field of automobile air conditioning, and in particular to a method for controlling the proportion of fresh air in an air conditioning system of an electric vehicle. Background Art

[0002] The air conditioning system is an essential component of electric vehicles, maintaining a comfortable cabin air environment through cooling and heating functions. With the rapid development of the electric vehicle industry in recent years, energy conservation has become a key research focus. As the auxiliary device that consumes the most energy in an electric vehicle, the research on energy-saving strategies for electric vehicle air conditioning systems is an essential research focus.

[0003] Research has shown that fresh air load is one of the primary loads on air conditioning systems during both cooling and heating. Therefore, research into reducing the fresh air load during the operation of electric vehicle air conditioning systems is highly relevant. Various strategies exist to reduce the fresh air load during air conditioning system operation, including the use of novel HVAC structures and heated windshields to reduce defogger requirements. However, introducing return air is the most cost-effective and easily implemented method. Therefore, studying the fresh air ratio introduced into air conditioning systems has practical implications for reducing the operating energy consumption of electric vehicle air conditioning systems.

[0004] Excessive carbon dioxide concentrations or high cabin humidity can negatively impact safe driving, necessitating the introduction of fresh air into the air conditioning system. The cabin's carbon dioxide concentration and humidity are closely related to the number of passengers. A higher number of passengers generates more carbon dioxide and water vapor through respiration, necessitating the introduction of more fresh air. Existing automotive air conditioning systems typically have a fixed fresh air ratio, which can lead to excessive fresh air waste. However, excessive fresh air ratios can increase energy consumption in the air conditioning system. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a fresh air ratio control method for an electric vehicle air-conditioning system, which intelligently adjusts the fresh air ratio and minimizes the negative impact of introducing fresh air on the energy consumption of the air-conditioning system.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for controlling the fresh air ratio of an electric vehicle air conditioning system includes the following steps:

[0008] When the air conditioner starts, the ventilation system operates in a full internal circulation mode, and the CO2 concentration in the vehicle is monitored during operation. When the air conditioner is in cooling mode, the ventilation ratio is calculated based on the CO2 concentration, and the ventilation mode is switched and the fresh air ratio of the air conditioner system is adjusted according to the ventilation ratio.

[0009] When the air conditioning system is in heating condition, the ventilation ratio is calculated based on the CO2 concentration and the glass fogging constraint, and the ventilation mode is switched according to the ventilation ratio and the fresh air ratio of the air conditioning system is adjusted.

[0010] Preferably, when the air conditioning system is in heating mode, the following steps are specifically included:

[0011] Step 1: Start the air conditioner, and the ventilation system of the air conditioner operates in a full internal circulation mode;

[0012] Step 2: Monitor the CO2 concentration inside the vehicle and determine the full return air time t1 and the minimum fresh air ratio η1 based on the limit of the CO2 concentration inside the vehicle;

[0013] Step 3: Monitor the maximum relative humidity of the air and determine the full return air time t2 and the minimum fresh air ratio η2 based on the maximum relative humidity of the air inside the vehicle;

[0014] Step 4: Based on η=min(η1, η2), determine the optimal fresh air ratio η under the final heating condition; based on t=min(t1, t2), determine the optimal full return air time t under the final heating condition;

[0015] Step 5: Determine the optimal ventilation ratio based on the optimal full return air time t and the optimal fresh air ratio η, adopt a mixed ventilation method, and adjust the fresh air ratio of the air conditioning system.

[0016] Furthermore, in step 1, when the air conditioner is first started, the ventilation system first operates in a full internal circulation mode until the CO2 concentration in the cabin reaches the set maximum value or the relative humidity of the air in the cabin reaches the set maximum value, and the ventilation system of the air conditioner begins to adopt a mixed ventilation mode.

[0017] Furthermore, in step 2, the calculation formula for the CO2 concentration in the cabin is determined based on the factors affecting the CO2 concentration in the cabin, and the specific values ​​of each parameter in the formula are determined based on the requirements of human comfort and other relevant requirements. When the number of occupants in the vehicle is different, the full return air time t1 and the minimum fresh air ratio η1 for introducing fresh air are determined respectively.

[0018] Furthermore, the full return air duration t is determined by taking the temperature of the glass as the dew point temperature, thereby determining the maximum humidity of the air in the cabin. The full return air duration t is then determined by calculating when the humidity reaches a threshold based on the humidity generated by human breathing.

[0019] Furthermore, in step 3, the maximum allowable relative humidity of the cabin air is determined based on the relevant parameters of the windshield and the environment; the calculation formula of the cabin humidity content is determined based on the influencing factors of the cabin air humidity content; the relative humidity of the cabin air is determined based on the relationship between relative humidity and humidity content; based on the determined maximum relative humidity of the cabin air and the cabin relative humidity calculation formula, the full return air time t2 and the minimum fresh air ratio η2 are determined.

[0020] Preferably, when the air conditioning system is in cooling mode, the following steps are specifically included:

[0021] Step 1: Start the air conditioner, and the ventilation system of the air conditioner begins to adopt a mixed ventilation mode;

[0022] Step 2: Based on the CO2 concentration limit in the cabin, determine the full return air time t and the minimum fresh air ratio η;

[0023] Step 3: Based on the determination of the full return air time t and the minimum fresh air ratio η, the working condition is determined.

[0024] Preferably, the fresh air ratio of the air-conditioning system is calculated based on the CO2 concentration threshold in the cabin, the number of people in the cabin, the average CO2 production, and the blower air volume, so that the amount of fresh air introduced and the amount of CO2 discharged outside the cabin reach a dynamic balance.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention provides a method for controlling the fresh air ratio in an electric vehicle air conditioning system. This method investigates an intelligent control strategy for the fresh air ratio in electric vehicle air conditioning systems and applies it to the development of electric vehicle air conditioners. This method effectively ensures the determination of the minimum fresh air ratio during ventilation. This strategy precisely adjusts the minimum fresh air ratio at the air intake of the air conditioning system based on the number of passengers in the vehicle, achieving maximum energy savings. Based on human comfort requirements, while maintaining a moderate CO2 concentration in the cabin and anti-fogging requirements for the windshield, the present invention determines the minimum fresh air ratio required by the electric vehicle air conditioning system for different numbers of passengers, ambient temperatures, and cabin set temperatures. This minimizes the fresh air load during air conditioning operation, achieving energy savings and enabling intelligent control of the fresh air ratio in the vehicle air conditioning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Develop a process for intelligent control of fresh air ratio in air conditioning systems under heating conditions;

[0028] Figure 2 This is an example of a ventilation method;

[0029] Figure 3The research process for determining the full return air time t and the minimum fresh air ratio η based on the CO2 concentration limit in the cabin;

[0030] Figure 4 The research process is to determine the full return air time t and the minimum fresh air ratio η based on the anti-fog requirements of the windshield. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0032] The present invention provides a method for controlling the fresh air ratio of an electric vehicle air-conditioning system. When the air-conditioning is first started, the ventilation system first operates in a full internal circulation mode. Then, by evaluating the constraints of carbon dioxide concentration and the dew point of glass fogging, the optimal ventilation ratio is calculated. Finally, the return air plan is determined according to the calculated ventilation ratio.

[0033] In cooling mode, the air conditioning system uses only CO2 to determine the fresh air ratio. In heating mode, the air conditioning system determines the fresh air ratio based on the CO2 concentration and the glass fogging constraint, that is, it needs to determine both the CO2 concentration and the fogging constraint.

[0034] like Figure 1 As shown, a fresh air ratio control method for an electric vehicle air-conditioning system of the present invention includes six steps in a heating working condition.

[0035] S1: Determine whether the air conditioner is in cooling or heating and ventilation mode;

[0036] S2: Based on the CO2 concentration limit in the cabin, determine the full return air time t1 and the minimum fresh air ratio η1;

[0037] S3: Based on the anti-fogging requirements of the windshield, determine the full return air duration t2 and the minimum fresh air ratio η2;

[0038] S4: Based on η=min(η1, η2), determine the minimum fresh air ratio η under the final heating condition;

[0039] S5: Based on t=min(t1, t2), determine the full return air duration t under the final heating condition;

[0040] S6: Based on the determination of the full return air time t and the minimum fresh air ratio η, the working condition is determined.

[0041] The present invention provides a ventilation method in step S1, as shown in the attached Figure 2When the air conditioner is first started, the ventilation system first operates in a full internal circulation mode until the CO2 concentration in the cabin reaches the set maximum value or the relative humidity of the air in the cabin reaches the set maximum value. The ventilation system of the air conditioner then starts to use a mixed ventilation mode and begins to introduce fresh air at the minimum fresh air ratio determined by calculation until the air conditioner stops operating.

[0042] The present invention also provides a research process for determining the full return air time t1 and the minimum fresh air ratio η1 based on the CO2 concentration limit in the cabin in step S2, as shown in the attached figure. Figure 3 As shown. Based on the factors affecting the CO2 concentration in the cabin, a calculation formula for the CO2 concentration in the cabin is determined. The specific values ​​of each parameter in the formula are determined based on the requirements for human comfort and other related requirements. When the number of passengers in the vehicle is different, the full return air duration and the minimum fresh air ratio introduced are determined respectively.

[0043] Step S2 is a strategy for limiting the internal recirculation time and fresh air ratio based on CO2 concentration limits. Determining the full return air duration: Due to internal recirculation, CO2 concentrations will continue to rise. The duration of full internal recirculation can be calculated based on the CO2 threshold, the number of passengers, and the cabin volume. Once the concentration reaches the threshold, internal recirculation mode is discontinued and fresh air must be introduced.

[0044] Determination of the proportion of fresh air: The national standard stipulates the CO2 concentration threshold in the passenger cabin, which is calculated based on the number of people, the average CO2 production per person, and the blower air volume. The ultimate goal is to maintain the CO2 concentration in the passenger cabin below the maximum threshold, that is, by introducing fresh air (introducing fresh air means that some of the original cabin air is discharged) to ensure that the CO2 produced by humans is discharged out of the cabin, achieving dynamic balance.

[0045] The present invention also provides a research process for determining the full return air time t2 and the minimum fresh air ratio η2 based on the anti-fog requirement of the windshield in step S3, as shown in the attached figure. Figure 4 As shown. Based on the relevant parameters of the windshield and the environment, the maximum allowable relative humidity of the cabin air is determined. Based on the factors affecting the cabin air moisture content, the calculation formula for the cabin moisture content is determined. Based on the relationship between relative humidity and moisture content, the relative humidity of the cabin air is determined. Based on the determined maximum relative humidity of the cabin air and the cabin relative humidity calculation formula, the full return air duration and minimum fresh air ratio are determined.

[0046] Step S3 is to determine the strategy of internal circulation time and fresh air ratio based on the constraint of glass fogging.

[0047] In heating mode, the windshield temperature is low and humid air will fog up when it comes into contact with the glass, so the air humidity in the cabin cannot be too high.

[0048] The temperature of the glass is used as the dew point temperature to determine the maximum humidity of the air in the cabin. Then, based on the humidity generated by human breathing, it is calculated when the humidity reaches the threshold to determine the full return air duration.

[0049] Then, similar to CO2, the maximum fresh air ratio is calculated based on information such as the relative humidity of the air outside / inside the vehicle, the air volume and the number of people, so as to achieve a dynamic balance between the water vapor generated by the passengers and the water vapor discharged from the cabin.

[0050] For cooling conditions, the only difference from heating conditions is that the air conditioning system does not need to consider the anti-fogging requirements of the windshield under cooling conditions, including the following steps:

[0051] Step 1: Start the air conditioner, and the ventilation system of the air conditioner begins to adopt a mixed ventilation mode;

[0052] Step 2: Based on the CO2 concentration limit in the cabin, determine the full return air time t and the minimum fresh air ratio η;

[0053] Step 3: Based on the determination of the full return air time t and the minimum fresh air ratio η, the working condition is determined.

[0054] Based on the requirements of human comfort, the present invention determines the minimum fresh air ratio required by the air-conditioning and ventilation system of electric vehicles under different numbers of occupants, different ambient temperatures, and different cabin set temperatures, while meeting the requirements of moderate CO2 concentration in the cabin and anti-fogging of the windshield. This maximizes the reduction of the fresh air load during the operation of the air-conditioning to achieve energy-saving effects and realizes intelligent control of the fresh air ratio of the automobile air-conditioning system.

Claims

1. A method for controlling the fresh air ratio of an electric vehicle air conditioning system, characterized in that: Including the following process, When the air conditioner starts, the ventilation system operates in a full internal circulation mode, and the CO2 concentration in the vehicle is monitored during operation. When the air conditioner is in cooling mode, the ventilation ratio is calculated based on the CO2 concentration, and the ventilation mode is switched and the fresh air ratio of the air conditioner system is adjusted according to the ventilation ratio. When the air conditioning system is in heating mode, the ventilation ratio is calculated based on the CO2 concentration and glass fogging constraints, and the ventilation mode is switched and the fresh air ratio of the air conditioning system is adjusted according to the ventilation ratio; When the air conditioning system is in heating mode, The following steps are included: Step 1: Start the air conditioner, and the ventilation system of the air conditioner operates in a full internal circulation mode; Step 2: Monitor the CO2 concentration inside the vehicle and determine the full return air time t1 and the minimum fresh air ratio η1 based on the limit of the CO2 concentration inside the vehicle; Step 3: Monitor the maximum relative humidity of the air and determine the full return air time t2 and the minimum fresh air ratio η2 based on the maximum relative humidity of the air inside the vehicle; Step 4: Based on η=min(η1, η2), determine the optimal fresh air ratio η under the final heating condition; Based on t=min(t1, t2), determine the optimal full return air duration t under the final heating condition; Step 5: Determine the optimal ventilation ratio based on the optimal full return air time t and the optimal fresh air ratio η, adopt a mixed ventilation mode, and adjust the fresh air ratio of the air conditioning system; When the air conditioning system is in cooling mode, it specifically includes the following steps: Step 1: Start the air conditioner, and the ventilation system of the air conditioner begins to adopt a mixed ventilation mode; Step 2: Based on the CO2 concentration limit in the cabin, determine the full return air time t and the minimum fresh air ratio η; Step 3: Based on the determination of the full return air time t and the minimum fresh air ratio η, the working condition is determined.

2. The method for controlling the fresh air ratio of an electric vehicle air conditioning system according to claim 1, characterized in that: In step 1 of the air conditioning system under the heating condition, when the air conditioning is first started, the ventilation system first operates in a full internal circulation mode until the CO2 concentration in the cabin reaches the set maximum value or the relative humidity of the air in the cabin reaches the set maximum value. The ventilation system of the air conditioning begins to adopt a mixed ventilation mode.

3. The method for controlling the fresh air ratio of an electric vehicle air conditioning system according to claim 1, wherein: In step 2 of the air-conditioning system under heating conditions, the calculation formula for the CO2 concentration in the cabin is determined based on the factors affecting the CO2 concentration in the cabin. The specific values ​​of each parameter in the formula are determined based on the requirements for human comfort and other relevant requirements. When the number of occupants in the vehicle is different, the full return air time t1 and the minimum fresh air ratio η1 for introducing fresh air are determined respectively.

4. The method for controlling the fresh air ratio of an electric vehicle air conditioning system according to claim 1, wherein: When the air conditioning system is operating in heating mode, the full return air duration t is determined by using the glass temperature as the dew point temperature to determine the maximum humidity of the air in the cabin. The full return air duration t is then determined based on the humidity generated by human breathing and when the humidity reaches the threshold.

5. The method for controlling the fresh air ratio of an electric vehicle air conditioning system according to claim 1, characterized in that: In step 3 of the air conditioning system under heating conditions, the maximum allowable relative humidity of the cabin air is determined based on the relevant parameters of the windshield and the environment; the calculation formula for the cabin humidity content is determined based on the factors affecting the cabin air humidity content; the relative humidity of the cabin air is determined based on the relationship between relative humidity and humidity content; and the full return air time t2 and the minimum fresh air ratio η2 are determined based on the determined maximum relative humidity of the cabin air and the cabin relative humidity calculation formula.

6. The method for controlling the fresh air ratio of an electric vehicle air conditioning system according to claim 1, characterized in that: The fresh air ratio of the air-conditioning system is calculated based on the CO2 concentration threshold in the cabin, the number of people in the cabin, the average CO2 production, and the blower air volume, so that a dynamic balance is achieved between the amount of fresh air introduced and the amount of CO2 discharged outside the cabin.

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