A novel fresh air outlet control method and system for an electric vehicle air conditioner based on fixed heat load

Abstract

The application provides a novel fresh air outlet control method and system for an electric vehicle air conditioner based on fixed heat load, and the method and system are based on the premise that the cold quantity of the outlet air in the full return air mode of the electric vehicle air conditioner meets the comfort requirement in the passenger cabin, and the accurate outlet air temperature in the full fresh air mode under the corresponding working condition is obtained according to the principle that the effective cold quantity in the full fresh air mode is consistent with the effective cold quantity in the full return air mode, and the timing of switching the electric vehicle air conditioner from the full return air mode to the full fresh air mode is determined according to the air quality, so that the air quality and temperature requirement of the passenger cabin can be completely met, and the energy consumption of the electric vehicle air conditioner in the full fresh air mode is greatly saved.

Description

Technical Field

[0001] This invention relates to a method and system for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load, belonging to the field of energy science and technology. Background Technology

[0002] With the global energy crisis becoming increasingly severe in recent years, the application and popularization of new energy electric vehicles have alleviated the problems of environmental pollution and fossil energy shortage. However, due to the limitation of electric vehicle battery capacity, the air conditioning system, which is efficient and can meet the comfort needs of passengers, has become an indispensable part of new energy electric vehicles.

[0003] Currently, electric vehicle air conditioning systems can support both 100% fresh air and full return air modes, primarily to meet passengers' comfort needs for temperature and humidity and maintain air quality within the passenger cabin. However, there is no detailed reference method for the switching timing between full return air and 100% fresh air modes, as well as the corresponding conversion of airflow volume and temperature. This results in a fixed or uncertain airflow volume in 100% fresh air mode, leading to an increase in the cooling load of 100% fresh air and wasted cooling capacity. Consequently, the temperature fluctuates and energy consumption increases during the switch from full return air to 100% fresh air mode within the passenger cabin.

[0004] In summary, this paper presents a method for calculating the air volume and temperature of the fresh air mode in an electric vehicle air conditioning system. Maintaining stable passenger comfort and ensuring healthy air quality while reducing energy consumption in the fresh air mode of the air conditioning system has become one of the major challenges currently facing electric vehicle thermal management systems, necessitating a new method for controlling the fresh air output of electric vehicle air conditioning systems. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load, so as to solve the energy waste problem of the fresh air operation mode of an electric vehicle air conditioner mentioned above.

[0006] This invention is achieved through the following technical solution:

[0007] A method for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load, comprising:

[0008] S1. When the passenger cabin environment reaches a stable state in the full return air mode of the electric vehicle air conditioner, acquire the temperature and humidity of the passenger cabin, as well as the outlet temperature, outlet humidity, and outlet air volume of the air conditioning unit; determine the effective cooling capacity in the full return air mode based on the temperature and humidity of the passenger cabin and the outlet temperature, outlet humidity, and outlet air volume of the air conditioning unit.

[0009] S2, obtain the air quality in the passenger cabin, and determine whether the triggering conditions for the electric vehicle air conditioner to switch from full return air mode to full fresh air mode are met based on the air quality.

[0010] S3, when the triggering condition described in S2 is met, the air conditioner of the electric vehicle switches from full return air mode to full fresh air mode, and sets the air volume of the air conditioning unit in full fresh air mode.

[0011] S4: Obtain the outlet humidity of the air conditioning unit in the fresh air mode, and calculate the effective cooling capacity in the fresh air mode by combining it with the outlet air volume of the air conditioning unit in the fresh air mode; based on the principle that the effective cooling capacity in the fresh air mode is consistent with the effective cooling capacity in the full return air mode, calculate the target outlet temperature in the fresh air mode, and control the outlet temperature of the air conditioning unit to the target outlet temperature.

[0012] Preferably, in S1, the method for determining whether the passenger cabin environment has reached a stable state under the full return air mode of the electric vehicle air conditioner is as follows: obtain the temperature inside the passenger cabin, and if the temperature inside the passenger cabin fluctuates by no more than 2°C within a preset time period, then the passenger cabin environment under the full return air mode of the electric vehicle air conditioner is considered to have reached a stable state.

[0013] Preferably, in S1, the effective cooling capacity in the full return air mode is determined based on the temperature and humidity of the passenger cabin and the outlet air temperature, outlet air humidity, and outlet air volume of the air conditioning unit, specifically as follows:

[0014] The enthalpy of the passenger cabin air under steady-state conditions in the full return air mode is calculated based on the temperature and humidity of the passenger cabin.

[0015] Based on the outlet air temperature and humidity of the air conditioning unit, the outlet air enthalpy value of the air conditioning unit in full return air mode is calculated.

[0016] The effective cooling capacity under full return air mode is calculated based on the passenger cabin air enthalpy, the air outlet enthalpy of the air conditioning unit, and the air outlet volume of the air conditioning unit under stable conditions.

[0017] Furthermore, the specific formula for calculating the effective cooling capacity under the full return air mode is as follows:

[0018] Q c1 =q cyc ·(h c -h cyc )

[0019] Where: q cyc The air volume of the air conditioning unit in full return air mode is kg / s;

[0020] h c The enthalpy of passenger cabin air under stable conditions in full return air mode is expressed in kJ / kg.

[0021] h cyc The enthalpy of the air supply from the air conditioning unit in full return air mode is expressed in kJ / kg.

[0022] Preferably, S2 specifically involves: obtaining the CO2 concentration in the air inside the passenger cabin, determining whether the CO2 concentration has reached the concentration threshold, and if so, considering that the triggering condition for the electric vehicle air conditioner to switch from full return air mode to full fresh air mode is met.

[0023] Furthermore, the concentration threshold is 2%-3% by volume.

[0024] Preferably, in S3, the air volume of the air conditioning unit in the fresh air mode is set to the maximum design air volume of the blower inside the air conditioning unit.

[0025] Preferably, in S4, the target outlet air temperature calculation method in the fresh air mode is as follows:

[0026] Q c1 =q cyc ·(h c -h cyc )=q m ·(h c -h n )=Q c2

[0027] Among them: Q c1 Q c2 The effective cooling capacity, in kW, is for both the full return air mode and the fresh air mode.

[0028] q cyc The air volume of the air conditioning unit in full return air mode is kg / s;

[0029] h c The enthalpy of passenger cabin air under stable conditions in full return air mode is expressed in kJ / kg.

[0030] h cyc The enthalpy of the air supply from the air conditioning unit in full return air mode is expressed in kJ / kg.

[0031] q m The air volume of the air conditioning unit in fresh air mode is kg / s;

[0032] h n The enthalpy of the air supply from the air conditioning unit in 100% fresh air mode is expressed in kJ / kg.

[0033] The enthalpy of the passenger cabin air under stable conditions in the full return air mode is calculated based on the temperature and humidity of the passenger cabin, and the enthalpy of the air outlet of the air conditioning unit in the full return air mode is calculated based on the outlet air temperature and humidity of the air conditioning unit in the full return air mode.

[0034] Based on the above formula, the enthalpy value h of the air supply unit in fresh air mode is calculated. n Combined with the humidity of the air outlet from the air conditioning unit in fresh air mode, the corresponding humid air temperature is the target fresh air outlet temperature T. n .

[0035] Preferably, after S4, the following is also included: calculating the CO2 concentration in the passenger cabin under 100% fresh air mode according to the following formula:

[0036]

[0037] in: The CO2 volume concentration in the passenger cabin at the end of the full return air mode, in ppm;

[0038] q is the rate at which each passenger exhales CO2, in g / h;

[0039] n is the number of passengers;

[0040] t represents the duration of the fresh air mode in seconds;

[0041] V c For passenger cabin volume, m 3 ;

[0042] q m The air volume of the air conditioning unit in 100% fresh air mode is expressed in kg / s.

[0043] ρ c,m The CO2 mass concentration in the passenger cabin monitored at the end of the full return air mode, in g / m³. 3 ;

[0044] ρ a,m CO2 mass concentration in the external environment of the passenger cabin, g / m³ 3 .

[0045] The CO2 concentration change in the fresh air mode calculated by the above formula will be switched from fresh air mode to full return air mode when the CO2 concentration is below the set concentration threshold within the monitoring frequency range of the preset time.

[0046] A fresh air supply control system for an electric vehicle air conditioner based on a fixed heat load includes: a passenger compartment temperature sensor, a passenger compartment humidity sensor, a passenger compartment air quality sensor, an air conditioner unit outlet temperature sensor, an air conditioner unit outlet humidity sensor, and a control module.

[0047] The passenger cabin temperature sensor is used to collect the temperature of the passenger cabin;

[0048] The passenger cabin humidity sensor is used to collect the humidity of the passenger cabin;

[0049] The passenger cabin air quality sensor is used to collect the air quality in the passenger cabin.

[0050] The air conditioner unit outlet air temperature sensor is used to collect the air temperature of the air conditioner unit.

[0051] The air humidity sensor at the air conditioner unit is used to collect the air humidity at the air conditioner unit.

[0052] The control module is used to determine the effective cooling capacity in the full return air mode based on the temperature and humidity of the passenger cabin and the outlet air temperature, outlet air humidity, and outlet air volume of the air conditioning unit; to determine whether the triggering conditions for the electric vehicle air conditioning to switch from the full return air mode to the 100% fresh air mode are met based on the air quality in the passenger cabin; when the triggering conditions are met, the control module controls the electric vehicle air conditioning to switch from the full return air mode to the 100% fresh air mode and sets the outlet air volume of the air conditioning unit in the 100% fresh air mode; and to calculate the target outlet air temperature in the 100% fresh air mode based on the outlet air humidity and outlet air volume of the air conditioning unit in the 100% fresh air mode, according to the principle that the effective cooling capacity in the 100% fresh air mode is consistent with the effective cooling capacity in the full return air mode, and control the outlet air temperature of the air conditioning unit to be the target outlet air temperature.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] In this invention, the method assumes that the cooling capacity of the electric vehicle air conditioner in the full return air mode meets the comfort requirements of the passenger cabin. Based on the principle that the effective cooling capacity in the fresh air mode is consistent with that in the full return air mode, the precise outlet temperature of the fresh air mode under the corresponding operating conditions is obtained. Furthermore, the timing for the electric vehicle air conditioner to switch from the full return air mode to the fresh air mode is determined based on the air quality. This method can not only fully meet the air quality and temperature requirements of the passenger cabin, but also greatly save the energy consumption of the electric vehicle air conditioner in the fresh air mode.

[0055] Furthermore, a comprehensive calculation formula is proposed to address the dynamic changes in overall carbon dioxide concentration inside the passenger compartment under 100% fresh air mode. Compared to directly using sensor measurements, this formula provides a more holistic description of the dynamic balance characteristics of air quality inside the passenger compartment. This avoids the inaccuracy of carbon dioxide concentration sensors in 100% fresh air mode due to factors such as localized fresh air intake and air leakage, thereby improving the accuracy of passenger air quality monitoring and further ensuring passenger comfort and health safety. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the electric vehicle air conditioning system (HVAC, heating, ventilation and air conditioning) and passenger cabin air circulation in an embodiment of the present invention. Detailed Implementation

[0057] To further understand the present invention, the present invention will be described below with reference to embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0058] Figure 1 This is a schematic diagram of the air circulation in the air conditioning unit and passenger compartment of an electric vehicle, as described in an embodiment of the present invention.

[0059] The electric vehicle air conditioning unit mainly includes an air inlet 1, which is equipped with a return air valve and a fresh air valve. Switching between the return air valve and the fresh air valve can change the air duct, realizing the conversion between full return air mode and full fresh air mode. An air inlet temperature sensor 2-1 and an air inlet humidity sensor 2-2 are installed at the air inlet 1 to monitor the air intake status. The speed of the blower 3 in the air conditioning unit can be adjusted to change the intake air volume; its speed is controllable. The intake air is cooled by a heat exchanger 4. An air outlet is equipped with an air outlet temperature sensor 6-1 and an air outlet humidity sensor 6-2 to monitor the outlet temperature and humidity. The air conditioning unit has three outlets corresponding to different parts of the passenger compartment, which are regulated by outlet valves 5.

[0060] The passenger cabin is equipped with a passenger cabin temperature sensor 7-1, a passenger cabin humidity sensor 7-2, and a passenger cabin air quality sensor to monitor the temperature, humidity, and air quality (CO2 concentration) in the passenger cabin; the rear pressure relief valve 8 discharges excess air from the passenger cabin to maintain pressure balance.

[0061] This invention relates to a fresh air supply control system for an electric vehicle air conditioner based on a fixed heat load, comprising: a passenger compartment temperature sensor, a passenger compartment humidity sensor, a passenger compartment air quality sensor, an air conditioning unit outlet temperature sensor, an air conditioning unit outlet humidity sensor, and a control module.

[0062] The passenger cabin temperature sensor is used to collect the temperature of the passenger cabin;

[0063] The passenger cabin humidity sensor is used to collect the humidity of the passenger cabin;

[0064] The passenger cabin air quality sensor is used to collect the air quality in the passenger cabin.

[0065] The air conditioner unit outlet air temperature sensor is used to collect the air temperature of the air conditioner unit.

[0066] The air conditioning unit's outlet humidity sensor is used to collect the outlet humidity of the air conditioning unit.

[0067] The airflow sensor of the air conditioning unit is used to collect the airflow volume of the air conditioning unit.

[0068] The control module is used to determine the effective cooling capacity in the full return air mode based on the temperature and humidity of the passenger cabin and the outlet air temperature, outlet air humidity, and outlet air volume of the air conditioning unit; to determine whether the triggering conditions for the electric vehicle air conditioning to switch from the full return air mode to the 100% fresh air mode are met based on the air quality in the passenger cabin; when the triggering conditions are met, the control module controls the electric vehicle air conditioning to switch from the full return air mode to the 100% fresh air mode and sets the outlet air volume of the air conditioning unit in the 100% fresh air mode; and to calculate the target outlet air temperature in the 100% fresh air mode based on the outlet air humidity and outlet air volume of the air conditioning unit in the 100% fresh air mode, according to the principle that the effective cooling capacity in the 100% fresh air mode is consistent with the effective cooling capacity in the full return air mode, and control the outlet air temperature of the air conditioning unit to be the target outlet air temperature.

[0069] This invention relates to a method for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load, which mainly includes:

[0070] S1, under specific environmental conditions, acquire the passenger cabin temperature, humidity, and air outlet temperature, humidity, and air volume parameters of the air conditioning unit when the passenger cabin environment reaches a stable state in the full return air mode of the electric vehicle air conditioning; based on the passenger cabin temperature, humidity, air outlet temperature, humidity, and air volume of the air conditioning unit, determine the effective cooling capacity requirement of the passenger cabin corresponding to temperature and humidity comfort.

[0071] S2, under the aforementioned operating conditions, during the operation of the electric vehicle air conditioner in full return air mode, the air quality in the passenger cabin is scanned at a frequency. In order to meet the needs of passenger health and comfort to the greatest extent, the triggering conditions for the electric vehicle air conditioner to switch from full return air mode to fresh air mode are determined based on the air quality.

[0072] S3. After the triggering conditions for switching to the fresh air mode are met, in order to ensure the rapid recovery of air quality in the passenger cabin and to meet the objective laws of the operation of the blower in the air conditioning unit, the air volume of the air conditioning unit in the fresh air mode is determined from these two aspects. At the same time, the air conditioning unit's return air valve, fresh air valve, air outlet valve, and passenger cabin pressure relief valve should work in accordance with the changes in the air intake duct and air volume to realize the conversion from the full return air mode to the fresh air mode;

[0073] S4, after switching from the full return air mode to the fresh air mode, calculates the effective cooling capacity provided to the passenger compartment by the air volume and humidity of the air conditioning unit in the fresh air mode. Finally, based on the principle that the effective cooling capacity in the fresh air mode is consistent with that in the full return air mode, the target outlet temperature in the fresh air mode is calculated, and the outlet temperature of the air conditioning unit is controlled to the target temperature. Thus, while ensuring passenger compartment temperature and humidity comfort and air quality, the additional load from fresh air is reduced, energy waste is avoided, and the operating efficiency of the electric vehicle's air conditioning system is improved.

[0074] In S1, the method for determining the effective cooling capacity requirement of the passenger cabin in full return air mode specifically includes:

[0075] S11, after the passenger turns on the electric vehicle's air conditioning, the air conditioning system prioritizes the target temperature in the passenger compartment. To ensure the target temperature is reached as quickly as possible, the full return air mode is activated, and the air outlet temperature T of the air conditioning unit in full return air mode is set according to the passenger's set target temperature. cyc ;

[0076] S12, in full return air mode, according to the air outlet temperature T of the air conditioning unit cyc After the set running time, the passenger cabin temperature and humidity sensors read the passenger cabin environmental parameters (temperature and humidity) to determine whether a stable state has been reached: if the passenger cabin temperature fluctuates by no more than 2°C within the preset time (e.g., 30 seconds), it is considered that the passenger cabin environment has reached a stable state in the full return air mode of the car air conditioning. The passenger cabin temperature sensor and passenger cabin humidity sensor then read the passenger cabin temperature T at this time. c and humidity H c The enthalpy h of the passenger cabin air under stable conditions in the full return air mode is determined by the temperature and humidity of the passenger cabin at this time. c ;

[0077] S13, When the passenger cabin environment reaches a stable state in full return air mode, the humidity H at the air outlet of the air conditioning unit is obtained through the humidity sensor at the air outlet of the air conditioning unit. cyc Based on the above settings, the outlet air temperature T of the air conditioning unit cyc The enthalpy value h of the air supply unit in full return air mode was calculated. cyc The air volume q of the air conditioning unit in full return air mode is obtained by measuring the working status of the blower. cyc ;

[0078] S14, the cooling capacity of an electric vehicle's air conditioning system that lowers the passenger cabin temperature is the effective cooling capacity. This is reflected in the temperature difference between the air outlet temperature of the air conditioning unit and the passenger cabin temperature, specifically the cooling capacity provided by the portion of air with this temperature difference in the air outlet. Based on the parameters described above for the full return air mode, the effective cooling capacity provided by the air conditioning system to the passenger cabin under the current operating conditions (which also meets the effective cooling capacity requirements for passenger cabin comfort) is calculated as follows:

[0079] Q c1 =q cyc ·(h c -h cyc )

[0080] Where: q cyc The air volume of the air conditioning unit in full return air mode is kg / s;

[0081] h cThe enthalpy of passenger cabin air under stable conditions in full return air mode is expressed in kJ / kg.

[0082] h cyc The value is the enthalpy of the air supply of the air conditioning unit in full return air mode, in kJ / kg.

[0083] In S2, the triggering conditions and judgment criteria for switching to the fresh air mode mainly include the following methods:

[0084] The air conditioning system of electric vehicles monitors the air quality inside the vehicle at a frequency using air quality sensors in the passenger compartment. According to GB50019-2003 Heating, Ventilation and Air Conditioning Design Code, CO2 concentration is mainly used as the standard for judging the air quality in the passenger compartment. The effects of indoor CO2 concentration on human health are shown in Table 1.

[0085] Table 1. Effects of Indoor CO2 Concentration on Human Health

[0086] <![CDATA[CO2 volume fraction / (%)]]> Main symptoms <0.1 normal air 1 Increased breathing has no significant impact on work efficiency. 2 Headaches, drowsiness, mild hearing loss, and reduced calculation efficiency 4 Difficulty breathing, lethargy, and a significant decrease in work efficiency 6 Severe headache, vomiting, mental confusion, and manic state. 7～9 Confusion occurred within about 1 hour 10～11 This can cause suffocation, fainting, and loss of consciousness in some individuals. 25～30 Stop breathing, loss of sensation, death several hours later

[0087] After the passenger cabin is kept in a stable state in the full return air mode of the electric vehicle air conditioner (usually 10 minutes), the CO2 concentration in the passenger cabin is read at a certain frequency (e.g., 30 times / s). Based on the influence of the CO2 concentration, the fresh air mode is turned on when the CO2 concentration is at the set concentration threshold (e.g., 3%, volume fraction).

[0088] In S3, the method for controlling the airflow and damper of the air conditioning unit in fresh air mode is as follows:

[0089] When the full return air mode reaches a stable state and the CO2 volume fraction in the passenger cabin reaches the set concentration threshold, the air conditioning will switch to full fresh air mode.

[0090] At this time, the air inlet of the electric vehicle's air conditioning unit is switched from a return air valve to a fresh air valve, thereby changing the air intake mode from full return air mode to full fresh air mode.

[0091] To quickly restore air quality in the passenger cabin, the blower inside the air conditioning unit needs to be rapidly increased to reach its maximum operating frequency, and the air volume of the air conditioning unit needs to reach its maximum design air volume (i.e., the maximum design air volume of the blower inside the air conditioning unit). At the same time, the pressure relief valve at the rear of the passenger cabin opens to expel air from the passenger cabin. The amount of air discharged is the sum of the air volume of the air conditioning unit in 100% fresh air mode and the amount of air leaked from the passenger cabin, thereby maintaining the air pressure balance in the passenger cabin.

[0092] The CO2 concentration in the passenger cabin under 100% fresh air mode is calculated using the following formula:

[0093]

[0094] in: The CO2 volume concentration in the passenger cabin at the end of the full return air mode, in ppm;

[0095] q is the rate at which each passenger exhales CO2, in g / h;

[0096] n is the number of passengers;

[0097] t represents the duration of the fresh air mode in seconds;

[0098] V c For passenger cabin volume, m 3 ;

[0099] q m The air volume of the air conditioning unit in 100% fresh air mode is expressed in kg / s.

[0100] ρ c,m The CO2 mass concentration in the passenger cabin monitored at the end of the full return air mode, in g / m³. 3 ;

[0101] ρ a,m CO2 mass concentration in the external environment of the passenger cabin, g / m³ 3 .

[0102] The CO2 concentration change calculated using the above formula under the new fresh air mode is considered to meet the passenger cabin air quality requirements when the CO2 concentration can reach below the set concentration threshold within the monitoring frequency range of the pre-approval time (e.g., 30 seconds), and the new fresh air mode can be switched to the full return air mode.

[0103] In S4, the calculation method for effective cooling capacity and outlet air temperature in fresh air mode is as follows:

[0104] Based on the fresh air volume determined by the above method for the fresh air mode, calculate the corresponding air outlet temperature.

[0105] To achieve the same cooling effect in 100% fresh air mode as in full return air mode, and to maintain the same temperature in the passenger cabin, both modes should bring in the same effective cooling capacity into the passenger cabin, which means satisfying the following equation:

[0106] Q c1 =q cyc ·(h c -h cyc )=q m ·(h c -h n )=Q c2

[0107] Among them: Q c1 Q c2 The effective cooling capacity, in kW, is for both the full return air mode and the fresh air mode.

[0108] q cycThe air volume of the air conditioning unit in full return air mode is kg / s;

[0109] h c The enthalpy of passenger cabin air under stable conditions in full return air mode is expressed in kJ / kg.

[0110] h cyc The enthalpy of the air supply from the air conditioning unit in full return air mode is expressed in kJ / kg.

[0111] q m The air volume of the air conditioning unit in fresh air mode is kg / s;

[0112] h n The value is the enthalpy of the air supply from the air conditioning unit in 100% fresh air mode, in kJ / kg.

[0113] Based on the above equations, the enthalpy of the air outlet of the air conditioning unit in 100% fresh air mode is calculated, and the humidity H of the air outlet of the air conditioning unit at this time is read. cyc The corresponding humid air temperature is the target fresh air outlet temperature T that should be set. n The target outlet air temperature of fresh air is obtained, and the air conditioner operation is adjusted through the control module to meet this target.

[0114] The present invention has the following advantages:

[0115] 1. This invention proposes a method for determining the air outlet temperature of the air conditioning unit when switching from full return air mode to fresh air mode during the operation of an electric vehicle's air conditioning. It proposes a comprehensive and widely applicable new strategy for the timing of switching to fresh air mode, the air volume, and the corresponding air outlet temperature. While ensuring the comfort of passengers during the operation of the electric vehicle's air conditioning, it reduces the additional energy consumption of the air conditioning fresh air, thereby improving the driving range of the electric vehicle.

[0116] 2. This invention provides a new strategy for switching the air conditioning system of an electric vehicle from full return air mode to full fresh air mode, clarifies the timing of starting the fresh air mode, and especially proposes a method for determining the air volume of the fresh air mode under certain conditions.

[0117] 3. This invention takes into account the temperature and humidity conditions and air quality of the passenger cabin, and reduces energy waste in the fresh air conditioning mode with the goal of energy saving, thereby increasing the driving range of electric vehicles when the air conditioning system is turned on.

[0118] 4. The method for calculating the outlet air temperature in the new air mode proposed in this invention only requires calculation based on the cooling load of the passenger cabin and the temperature and humidity sensor data at conventional locations, on the basis of full return air. The calculation method is simple and the device is conventionally installed.

Claims

1. A method for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load, characterized in that, include: S1. When the passenger cabin environment reaches a stable state in the full return air mode of the electric vehicle air conditioner, acquire the temperature and humidity of the passenger cabin, as well as the outlet temperature, outlet humidity, and outlet air volume of the air conditioning unit; determine the effective cooling capacity in the full return air mode based on the temperature and humidity of the passenger cabin and the outlet temperature, outlet humidity, and outlet air volume of the air conditioning unit. S2, obtain the CO2 concentration in the air inside the passenger cabin, determine whether the CO2 concentration has reached the concentration threshold, if it has, then it is considered that the trigger condition for the electric vehicle air conditioner to switch from full return air mode to full fresh air mode is met. S3, when the triggering condition described in S2 is met, the air conditioner of the electric vehicle switches from full return air mode to full fresh air mode, and sets the air volume of the air conditioning unit in full fresh air mode. S4. Obtain the outlet humidity of the air conditioning unit in the fresh air mode, and calculate the effective cooling capacity in the fresh air mode by combining it with the outlet air volume of the air conditioning unit in the fresh air mode. Based on the principle that the effective cooling capacity in the fresh air mode is consistent with the effective cooling capacity in the full return air mode, calculate the target outlet temperature in the fresh air mode, and control the outlet temperature of the air conditioning unit to the target outlet temperature. In S4, the target outlet air temperature is calculated in the fresh air mode as follows: in: , The effective cooling capacity, in kW, is for both the full return air mode and the fresh air mode. This refers to the airflow output of the air conditioning unit in full return air mode. ; The enthalpy of passenger cabin air under stable conditions in full return air mode is expressed in kJ / kg. The enthalpy of the air supply from the air conditioning unit in full return air mode is expressed in kJ / kg. This refers to the airflow volume of the air conditioning unit in fresh air mode. ; The enthalpy of the air supply from the air conditioning unit in 100% fresh air mode is expressed in kJ / kg. The enthalpy of the passenger cabin air under stable conditions in the full return air mode is calculated based on the temperature and humidity of the passenger cabin, and the enthalpy of the air outlet of the air conditioning unit in the full return air mode is calculated based on the outlet air temperature and humidity of the air conditioning unit in the full return air mode. Based on the above formula, the enthalpy of the air supply from the air conditioning unit in fresh air mode is calculated. Combined with the humidity of the air outlet from the air conditioning unit in fresh air mode, the corresponding humid air temperature is the target fresh air outlet temperature. ; Following S4, the calculation of CO2 concentration in the passenger cabin under 100% fresh air mode is also included, based on the following formula: ] in: The CO2 volume concentration in the passenger cabin at the end of the full return air mode, in ppm; q is the rate at which each passenger exhales CO2, in g / h; For the number of passengers; Duration of fresh air mode activation, seconds; For passenger cabin volume, ; The air volume of the air conditioning unit in 100% fresh air mode is expressed in kg / s. The CO2 mass concentration in the passenger cabin monitored at the end of the full return air mode, in g / ; CO2 mass concentration in the external environment of the passenger cabin, g / ; The CO2 concentration change in the fresh air mode calculated by the above formula will be switched from fresh air mode to full return air mode when the CO2 concentration is below the set concentration threshold within the monitoring frequency range of the preset time.

2. The method for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load according to claim 1, characterized in that, In S1, the method for determining whether the passenger cabin environment has reached a stable state under the full return air mode of the electric vehicle air conditioning is as follows: obtain the temperature inside the passenger cabin. If the temperature inside the passenger cabin fluctuates by no more than 2°C within a preset time period, it is considered that the passenger cabin environment under the full return air mode of the electric vehicle air conditioning has reached a stable state.

3. The method for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load according to claim 1, characterized in that, In S1, the effective cooling capacity in the full return air mode is determined based on the temperature and humidity of the passenger cabin, as well as the outlet air temperature, outlet air humidity, and outlet air volume of the air conditioning unit. Specifically: The enthalpy of the passenger cabin air under steady-state conditions in the full return air mode is calculated based on the temperature and humidity of the passenger cabin. Based on the outlet air temperature and humidity of the air conditioning unit, the outlet air enthalpy value of the air conditioning unit in full return air mode is calculated. The effective cooling capacity under full return air mode is calculated based on the passenger cabin air enthalpy, the air outlet enthalpy of the air conditioning unit, and the air outlet volume of the air conditioning unit under stable conditions.

4. The method for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load according to claim 3, characterized in that, The specific formula for calculating the effective cooling capacity under full return air mode is as follows: in: This refers to the airflow output of the air conditioning unit in full return air mode. ; The enthalpy of passenger cabin air under stable conditions in full return air mode is expressed in kJ / kg. The value is the enthalpy of the air supply of the air conditioning unit in full return air mode, in kJ / kg.

5. The method for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load according to claim 1, characterized in that, The concentration threshold is 2%-3% by volume.

6. The method for controlling the fresh air supply of an electric vehicle air conditioner based on a fixed heat load according to claim 1, characterized in that, In S3, the air volume of the air conditioning unit in the fresh air mode is set to the maximum design air volume of the blower inside the air conditioning unit.

7. A fresh air supply control system for an electric vehicle air conditioner based on a fixed heat load, characterized in that, include: Passenger cabin temperature sensor, passenger cabin humidity sensor, passenger cabin air quality sensor, air conditioning unit outlet air temperature sensor, air conditioning unit outlet air humidity sensor, control module; The passenger cabin temperature sensor is used to collect the temperature of the passenger cabin; The passenger cabin humidity sensor is used to collect the humidity of the passenger cabin; The passenger cabin air quality sensor is used to collect the air quality in the passenger cabin. The air conditioner unit outlet air temperature sensor is used to collect the air temperature of the air conditioner unit. The air humidity sensor at the air conditioner unit is used to collect the air humidity at the air conditioner unit. The control module is used to determine the effective cooling capacity in the full return air mode based on the temperature and humidity of the passenger cabin and the outlet air temperature, outlet air humidity, and outlet air volume of the air conditioning unit; to obtain the CO2 concentration in the air inside the passenger cabin and determine whether the CO2 concentration reaches the concentration threshold. If it does, it is considered that the trigger condition for the electric vehicle air conditioning to switch from the full return air mode to the fresh air mode is met. When the trigger condition is met, the electric vehicle air conditioning is controlled to switch from the full return air mode to the fresh air mode, and the outlet air volume of the air conditioning unit in the fresh air mode is set; based on the outlet air humidity and outlet air volume of the air conditioning unit in the fresh air mode, and according to the principle that the effective cooling capacity in the fresh air mode is consistent with the effective cooling capacity in the full return air mode, the target outlet air temperature in the fresh air mode is calculated, and the outlet air temperature of the air conditioning unit is controlled to be the target outlet air temperature; wherein, the calculation method of the target outlet air temperature in the fresh air mode is as follows: in: , The effective cooling capacity, in kW, is for both the full return air mode and the fresh air mode. This refers to the airflow output of the air conditioning unit in full return air mode. ; The enthalpy of passenger cabin air under stable conditions in full return air mode is expressed in kJ / kg. The enthalpy of the air supply from the air conditioning unit in full return air mode is expressed in kJ / kg. This refers to the airflow volume of the air conditioning unit in fresh air mode. ; The enthalpy of the air supply from the air conditioning unit in 100% fresh air mode is expressed in kJ / kg. The enthalpy of the passenger cabin air under stable conditions in the full return air mode is calculated based on the temperature and humidity of the passenger cabin, and the enthalpy of the air outlet of the air conditioning unit in the full return air mode is calculated based on the outlet air temperature and humidity of the air conditioning unit in the full return air mode. Based on the above formula, the enthalpy of the air supply from the air conditioning unit in fresh air mode is calculated. Combined with the humidity of the air outlet from the air conditioning unit in fresh air mode, the corresponding humid air temperature is the target fresh air outlet temperature. ; The CO2 concentration in the passenger cabin under 100% fresh air mode is calculated using the following formula: ] in: The CO2 volume concentration in the passenger cabin at the end of the full return air mode, in ppm; q is the rate at which each passenger exhales CO2, in g / h; For the number of passengers; Duration of fresh air mode activation, seconds; For passenger cabin volume, ; The air volume of the air conditioning unit in 100% fresh air mode is expressed in kg / s. The CO2 mass concentration in the passenger cabin monitored at the end of the full return air mode, in g / ; CO2 mass concentration in the external environment of the passenger cabin, g / ; The CO2 concentration change in the fresh air mode calculated by the above formula will be switched from fresh air mode to full return air mode when the CO2 concentration is below the set concentration threshold within the monitoring frequency range of the preset time.

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