Energy-saving control method and system for electric vehicle thermal management system based on weighted PMV model

Abstract

The application discloses a kind of energy-saving control method and system of electric vehicle thermal management system based on weighted PMV model, belong to refrigeration and low temperature engineering technical field.The system is cross-critical CO2 automobile heat pump air conditioning system, energy-saving PID controller is introduced in it, the PMV value is used as the input of the PID controller, and the relative relationship between the real-time PMV value in the control process and the target PMV value is adjusted to control the system return air temperature target value.The return air temperature PID controller controls the fan flow of the system by the relative relationship between the input return air temperature target value and the actual system return air temperature, so that the actual system return air temperature changes.By the energy-saving control method proposed in the application, the use of the coupled system model of multi-PID control can control the process algorithm according to the actual system parameters and working conditions, and perform energy-saving control on the system on the basis of meeting the comfort requirements of passenger compartment.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration and cryogenic engineering technology, specifically relating to an energy-saving control method and system for an electric vehicle thermal management system based on a weighted PMV model. Background Technology

[0002] Electric vehicles (EVs) have become an important direction for automotive development due to their outstanding environmental characteristics, and their development is of great significance. However, the lack of engine waste heat in EVs makes winter heating a necessity. The commonly used PTC electric heaters significantly reduce the winter driving range of EVs, severely impacting the prospects for the widespread adoption of EV technology in cold and frigid regions. In terms of summer cooling requirements, traditionally used HFC refrigerants have a high global warming index.

[0003] CO2, as a natural working fluid obtained directly from the atmosphere, possesses unparalleled environmental friendliness and high safety compared to other refrigerants. Its excellent low-temperature fluidity also makes it suitable for operation in cold winter conditions. Furthermore, the temperature glide characteristics of CO2 in the supercritical region give transcritical CO2 systems outstanding heating advantages, enabling them to operate in heat pump mode at ambient temperatures as low as -30 degrees Celsius, providing stable heating capacity. Therefore, transcritical CO2 automotive heat pump air conditioning technology is highly worthy of promotion and application in the new energy vehicle sector. However, currently used electric vehicle air conditioning control methods are still based on R134a refrigerant, relying mainly on application experience and engineering expertise accumulated over long-term use. They lack comfort evaluation indicators and are directly fixed in the electric vehicle thermal management system through offline control, lacking the ability to calculate and optimize in real time. Considering that CO2 thermal management technology significantly increases the outlet air temperature and system complexity compared to traditional R134a thermal management technology, existing mature control logic is not suitable for the new CO2 thermal management technology.

[0004] During the operation of a transcritical CO2 automotive heat pump air conditioning system, the energy-saving control method based on the weighted PMV model of comfort evaluation index enables the system to dynamically control the air conditioning system parameters according to the PMV value of the passenger cabin comfort index during operation. Under the premise of meeting the passenger cabin comfort, the cooling or heating demand required for the air conditioning system to operate is reduced, thereby reducing the compressor's operating power consumption and achieving the effect of energy saving. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an energy-saving control method and system for electric vehicle thermal management system based on weighted PMV model, so as to solve the problem that the CO2 thermal management technology in the prior art does not have the ability to calculate and optimize in real time.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] An energy-saving control method for electric vehicle thermal management systems based on a weighted PMV model includes the following steps:

[0008] Step 1: Set preset parameters and adjust the exhaust pressure, return air temperature, and supply air temperature of the transcritical CO2 heat pump air conditioning system in the electric vehicle to meet the preset parameters; collect real-time parameters inside the vehicle.

[0009] Step 2: Activate the energy-saving PID controller; the energy-saving PID controller calculates the target PMV based on preset parameters. target The value is calculated based on real-time weighted values ​​collected from inside the vehicle. Value, based on target PMV target and real-time weighting The target value for return air temperature is obtained through value calculation;

[0010] Step 3: The return air temperature PID controller adjusts the output compressor speed according to the target value of the return air temperature, thereby adjusting the return air temperature, and the real-time parameters inside the vehicle change.

[0011] Step 4: Repeat steps 2 and 3 until real-time weighting is achieved. The value meets the pre-set conditions.

[0012] A further improvement of the present invention is that:

[0013] Preferably, in step 1, the preset parameters include the number of passengers in the passenger compartment n, the internal volume of the passenger compartment V, and the ambient temperature T. env Energy efficiency rating m, system exhaust pressure target value P target Target value of return air temperature T in , target and the target value of supply air temperature T out,target .

[0014] Preferably, in step 1, the exhaust pressure is made to reach the preset parameter by the exhaust pressure PID controller, the supply air temperature is made to reach the preset parameter by the supply air PID controller, and the return air temperature is made to reach the preset parameter by the return air PID controller.

[0015] Preferably, the exhaust pressure PID controller controls the exhaust pressure by adjusting the opening of the electronic expansion valve, the supply air temperature PID controller adjusts the supply air temperature by adjusting the fan speed, and the return air temperature PID controller controls the return air temperature by adjusting the compressor speed.

[0016] Preferably, in step 2, the real-time parameters inside the vehicle include the temperature of various parts of the human body, the air velocity inside the vehicle, and the humidity inside the vehicle.

[0017] Preferably, in step 2,

[0018] In cooling mode, target PMV target The calculation formula is:

[0019] PMV target =f a (n,V,T env ,m,P target ,T in，target ,T out,target (1)

[0020] In heating mode, target PMV target The calculation formula is:

[0021] PMV target =f b (n,V,T env ,m,P target ,T in，target ,T out,target (2)

[0022] Where n is the number of passengers in the passenger cabin, V is the internal volume of the passenger cabin, and T is the internal volume of the passenger cabin. env For ambient temperature, m represents the energy efficiency rating, and P represents the energy efficiency rating. target The system exhaust pressure target value, T in，target For the target value of return air temperature and T out,target This is the target value for the supply air temperature.

[0023] Preferably, in step 2, real-time weighting is performed. The formula for calculating the value is:

[0024]

[0025] Among them, PMV i The PMV model calculation values ​​for various parts of the human body, ω i denoted by , where is the proportional weight of thermal sensation in different parts of the human body, and j represents the number of measurements taken from each part of the human body.

[0026] Preferably, in step 2, the target value of the return air temperature satisfies the following formula (6). If it does not satisfy the formula, the PI parameter of the energy-saving PID controller is adjusted.

[0027]

[0028] Where, ΔT in,target Here, m represents the return air temperature target, n represents the energy efficiency rating, and T represents the number of passengers in the cabin. env V represents the ambient temperature, and P represents the internal volume of the crew cabin. target The system exhaust pressure target value, T in，target T is the target value for return air temperature. out,target This is the target value for the supply air temperature.

[0029] Preferably, in step 4, the pre-set conditions are:

[0030] ΔPMV≤0.001&|PMV-PMV target |≤0.005 (7)

[0031] Where ΔPMV represents the fluctuation, and PMV represents the weighted average. Value, PMV target for Target value.

[0032] An energy-saving control system for electric vehicle thermal management systems based on a weighted PMV model includes:

[0033] The preset module sets preset parameters and adjusts the exhaust pressure, return air temperature, and supply air temperature of the transcritical CO2 heat pump air conditioning system in electric vehicles to meet the preset parameters; it also collects real-time parameters inside the vehicle.

[0034] The energy-saving PID controller module is used to activate the energy-saving PID controller; the energy-saving PID controller calculates the target PMV based on preset parameters. target The value is calculated based on real-time weighted values ​​collected from inside the vehicle. Value, based on target PMV target and real-time weighting The target value for return air temperature is obtained through value calculation;

[0035] The return air temperature PID controller module is used to adjust the output compressor speed according to the return air temperature target value, thereby adjusting the return air temperature and causing real-time changes in the parameters inside the vehicle.

[0036] The loop output module is used to repeatedly execute the energy-saving PID controller module and the return air temperature PID controller module until real-time weighted calculation is performed. The value meets the pre-set conditions.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] This invention discloses an energy-saving control method for an electric vehicle thermal management system based on a weighted PMV model. The system is a transcritical CO2 automotive heat pump air conditioning system, incorporating an energy-saving PID controller. This controller uses the PMV value as its input and adjusts the system's return air temperature target value based on the relative relationship between the real-time PMV value in the passenger compartment and the target PMV value during the control process. The output of the energy-saving PID controller is the system's return air temperature target value, which is transmitted to the system's return air temperature PID controller. This controller adjusts the system's fan airflow based on the relative relationship between the input return air temperature target value and the actual system return air temperature, thereby changing the actual system return air temperature. By combining the proposed energy-saving control method with a coupled system model of multi-PID control, the system can achieve energy-saving control based on actual system parameters and operating conditions, while meeting passenger compartment comfort requirements. This solves the energy-saving and emission-reduction problems of such systems under practical application conditions and has significant reference value in related industries within the new energy vehicle field.

[0039] Furthermore, this invention uses a design logic flowchart based on a weighted PMV value of comfort evaluation indicators for control, obtaining energy-saving stable operating parameters under specific conditions. This stable operating condition aims to reduce compressor power consumption during the operation of the transcritical CO2 automotive heat pump air conditioning system while meeting the comfort requirements of the passenger cabin. This innovative method for energy saving and emission reduction during the operation of transcritical CO2 automotive heat pump air conditioning systems has significant reference value.

[0040] Furthermore, this invention proposes a method for judging the rate of change of the return air temperature target value in the aforementioned energy-saving control method based on the weighted PMV model. The rate of change of the return air temperature target value must be within a reasonable range to ensure the stability of the entire control method. Before using the energy-saving control method based on the weighted PMV model, the system needs to first determine a preset return air temperature. Only when the supply air temperature and exhaust pressure reach the target values, and the system's return air temperature reaches the preset return air temperature, can the control method based on the weighted PMV model be introduced to achieve stable control of the target parameters. This has good reference value for system control in the industry. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of a transcritical CO2 automotive heat pump air conditioning system according to the present invention;

[0042] Figure 2 This is a flowchart of an energy-saving control method based on a weighted PMV model according to the present invention.

[0043] Among them, 1-outdoor heat exchanger; 2-outdoor fan; 3-CO2 compressor; 4-four-way reversing valve; 5-gas-liquid separator; 6-regenerator; 7-throttle valve; 8-indoor heat exchanger; 9-electric vehicle. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings:

[0045] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] An energy-saving control algorithm for an electric vehicle thermal management system based on a weighted PMV model is proposed. This algorithm uses a multi-PID control parameter method to achieve a stable return air temperature that reaches the preset target value. Based on this stable state, a new energy-saving PID controller is introduced. The target return air temperature of the vehicle's air conditioning system is controlled by the output value of the weighted PMV model of the passenger compartment comfort index and the target PMV value. Furthermore, the rate of change of the target return air temperature is kept low during the control process. By controlling the return air temperature of the system through the target return air temperature, the thermal environment of the passenger compartment is adjusted. This reduces the demand for cooling or heating in the passenger compartment while ensuring comfort, thereby reducing the power consumption of the CO2 compressor during the operation of the transcritical CO2 heat pump air conditioning system in new energy vehicles.

[0047] See Figure 1 The transcritical CO2 heat pump air conditioning system for new energy vehicles includes a CO2 compressor 3, a four-way reversing valve 4, an outdoor heat exchanger 8, a regenerator 6, a throttling valve 7, an indoor heat exchanger 8, and a gas-liquid separator 5.

[0048] In the transcritical CO2 system refrigeration cycle: the outlet of CO2 compressor 3 is connected to the inlet of four-way reversing valve 4, the outlet of four-way reversing valve 4 is connected to the inlet of outdoor heat exchanger 1, the outlet of outdoor heat exchanger 1 is connected to the inlet of regenerator 6, the outlet of regenerator 6 is connected to throttle valve 7, throttle valve 7 is connected to the medium inlet of indoor heat exchanger 8, the medium outlet of indoor heat exchanger 8 is connected to the inlet of four-way reversing valve 4, the outlet of four-way reversing valve 4 is connected to the inlet of gas-liquid separator 5, the outlet of gas-liquid separator 5 is connected to the inlet of regenerator 6, and the outlet of regenerator 6 is connected to the inlet of CO2 compressor 3; indoor heat exchanger 8 is located inside electric vehicle 9 and provides air supply and return for electric vehicle 9.

[0049] The energy-saving control method based on the weighted PMV model is as follows:

[0050] A weighted PMV model is used as a comfort index to evaluate the non-uniform thermal environment of the vehicle passenger compartment. The PMV value is the calculated output value of the model during the control process. The target PMV value for the control process is pre-calculated, and fixed parameters are set during the calculation process: the number of passengers in the passenger compartment (n), the internal volume of the passenger compartment (V), and the ambient temperature (T). env Energy efficiency rating m, system exhaust pressure target value P target Target value of return air temperature T in，target Target value of supply air temperature T out,target The target PMV value in the control process is determined by calculating the above operating parameters. Specifically, in cooling mode, the following values ​​are included:

[0051] PMV target =f a (n,V,T env ,m,P target ,T in，target ,T out,target (1)

[0052] Heating mode has

[0053] PMV target =f b (n,V,T env ,m,P target ,T in，target ,T out,target (2)

[0054] Among them, f a and f b These are all different function forms corresponding to different modes.

[0055] Since the weighted PMV model shows a positive correlation between PMV values ​​and air temperature, with air temperature having the largest influence factor, the real-time PMV value of the passenger compartment can be controlled by altering the thermal environment parameters of the passenger compartment through the control system's return air temperature. A multi-PID control parameter method is used to stabilize the system's return air temperature at the preset target value. Based on this stable state, a new energy-saving PID controller is introduced, using the PMV value as its input. The system's return air temperature target value is adjusted by controlling the relative relationship between the real-time PMV value of the passenger compartment and the target PMV value during the control process. The output of the energy-saving PID controller is the system's return air temperature target value, which is transmitted to the system's return air temperature PID controller. This controller adjusts the system's fan airflow based on the relative relationship between the input return air temperature target value and the actual system return air temperature, thus changing the actual system return air temperature. When the return air temperature changes, the passenger compartment's thermal environment parameters also change, i.e., the real-time PMV value also changes. The PMV value is re-input into the energy-saving PID controller, and the above control process is repeated. This allows the actual PMV value to gradually approach and eventually stabilize at the pre-calculated PMV target value. The logic flowchart of the energy-saving control method is as follows: Figure 1 As shown.

[0056] That is, the system is equipped with a total of 4 PID controllers, whose functions are as follows: ① Exhaust pressure PID controller, which controls the system exhaust pressure by adjusting the opening of the electronic expansion valve to achieve the optimal exhaust pressure value, thereby obtaining the optimal performance of the entire transcritical carbon dioxide cycle; ② Supply air temperature PID controller, which adjusts the supply air temperature by adjusting the fan speed to achieve a comfortable supply air temperature; ③ Return air temperature PID controller, which adjusts the compressor speed to regulate the cooling or heating capacity, ultimately affecting the temperature of the entire passenger compartment, thereby controlling the return air temperature; ④ Energy saving PID controller, which outputs the optimal return air temperature setpoint based on the current operating conditions and the current PMV value, thereby obtaining the optimal passenger comfort under the current conditions.

[0057] Upon final stabilization, since the PMV target value is a pre-calculated comfort threshold, the system's cooling or heating capacity requirement under this condition is just sufficient to meet comfort requirements. Compared to an empirically given preset return air temperature, the system's cooling and heating capacity will decrease. Under the same system supply air temperature target value, the system's compressor speed will decrease, thus reducing compressor power consumption. The system supply air temperature is controlled by a supply air temperature PID controller. This control method enables the system to reduce power consumption of the transcritical CO2 heat pump air conditioning system for new energy vehicles while maintaining passenger cabin thermal comfort.

[0058] See Figure 2Specifically, the method includes the following steps:

[0059] Step 1: Turn off the energy-saving PID controller, set the number of passengers in the passenger compartment n, the internal volume of the passenger compartment V, and the ambient temperature T. env Energy efficiency rating m, system exhaust pressure target value P target Target value of return air temperature T in , target Target value of supply air temperature T out,target .

[0060] First, the initial exhaust pressure and initial return air temperature of the system are preset. The system is then operated in a steady state by relying solely on the exhaust pressure PID controller, the supply air temperature PID controller, and the return air temperature PID controller. That is, the system exhaust pressure, return air temperature, and supply air temperature are all relatively stable and reach the initial preset values, satisfying the following equations (3) and (4).

[0061] ΔT in ≤0.001&ΔP dis ≤0.001&ΔT out ≤0.001 (3)

[0062] |T in -T in,target |≤0.005&|P dis -P target |≤0.005&|T out -T out,target |≤0.005 (4)

[0063] Among them, T in For real-time return air temperature, T in,target P is the target value for return air temperature. target System exhaust pressure target value, P dis For real-time system exhaust pressure, T out For real-time supply air temperature, T out,target This is the target value for the supply air temperature.

[0064] Step 2: Activate the PMV value PID controller (i.e., the energy-saving PID controller), and determine the target PMV value based on formulas (1) and (2) with the return air temperature target value as the independent variable. At the same time, collect the temperature, humidity, wind speed and other measurement points of various parts of the human body under the current steady-state conditions, calculate the current real-time weighted PMV value and output it to the energy-saving PID controller.

[0065] The specific calculation methods for the weighted PMV model include:

[0066] The weighted PMV model calculates values ​​by weighting the PMV values ​​of different parts of the human body. The weighted values ​​for each part are based on local thermal sensation, which represents the sensitivity of different parts of the body to changes in the thermal environment. Compared to the area-weighted method, it can more accurately reflect the overall comfort level of the human body. The temperature T at various measuring points on different parts of the human body within the passenger cabin is detected. i air velocity V i With humidity d, j human body parts were sampled, and the thermal resistance coefficient I was set. cl Inputting this into the PMV calculation model yields the PMV calculated for each part of the human body. i Confirm the proportional weighting of thermal sensation in different parts of the human body ω. i The weighted PMV model value is calculated using this weight. Its expression is:

[0067]

[0068] Step 3: The energy-saving PID controller outputs the target value of the return air temperature to the return air temperature PID controller. The return air temperature PID controller outputs the compressor speed requirement based on the target value of the return air temperature. With the adjustment of the compressor speed, the return air temperature is changed.

[0069] Due to the change ΔT in the target value of the return air temperature during the control process. in,target This will cause changes in system coupling parameters and the thermal environment of the crew compartment. Therefore, the rate of change of the target return air temperature must be within a reasonable range to ensure the stability of the entire control method. Its expression is:

[0070]

[0071] Where m represents the energy efficiency rating and n represents the number of passengers in the cabin.

[0072] In the process of using the energy-saving control method based on the weighted PMV model, controlling the rate of change of the return air temperature target value within a reasonable range is a crucial step. Since the system state is regulated by multiple PID control parameters, even a small change in the return air temperature target value will cause the other three PID controllers to adjust the system parameters. If the rate of change of the return air temperature target value changes too quickly, it will cause the coupling adjustment of various system parameters to be too fast, which will cause the oscillation and instability of the system parameters, and may even lead to control opposite to the target. If the above equation (6) is not satisfied, the PI parameters of the energy-saving PID controller should be reduced and the energy-saving PID controller should be adjusted until the return air temperature target value output by the energy-saving PID controller satisfies equation (6).

[0073] On the other hand, before using the energy-saving control method based on the weighted PMV model, the system needs to first determine a preset return air temperature. The system's return air temperature must reach the preset return air temperature simultaneously with the supply air temperature and exhaust pressure reaching their target values ​​before the weighted PMV model control method can be implemented. Otherwise, excessive adjustment of the new PID controller will lead to oscillations in system parameters, making the control method difficult to implement. Specifically, the preset return air temperature is: in the pure return air mode of a transcritical CO2 heat pump air conditioning system, the return air temperature is generally given a specific target value based on past experience; this target value is the preset return air temperature. Before introducing the energy-saving control method based on the weighted PMV model, the system needs to first reach a steady state where the target return air temperature is the preset return air temperature. Introducing the energy-saving control method based on this steady state can achieve a stable control process.

[0074] The return air temperature PID controller specifically includes:

[0075] In a PID controller, the actual system return air temperature is controlled by adjusting the compressor speed. In cooling mode, increasing the compressor speed increases the cooling capacity, thus lowering the system return air temperature. In heating mode, increasing the compressor speed increases the heating capacity, thus raising the system return air temperature. By comparing the actual system return air temperature with the target return air temperature, the compressor speed is adjusted to gradually control the system return air temperature to approach and eventually stabilize at the target value.

[0076] The supply air temperature PID controller specifically includes:

[0077] In a PID controller, the actual system's supply air temperature is controlled by adjusting the fan airflow. In cooling mode, increasing the fan airflow raises the system's supply air temperature. In heating mode, increasing the fan airflow lowers the system's supply air temperature. By comparing the actual system's supply air temperature with the target value, the system gradually adjusts the fan airflow to approach and eventually stabilize the supply air temperature at the target value.

[0078] The exhaust pressure PID controller specifically includes:

[0079] In a transcritical CO2 cycle, there exists the concept of optimal exhaust pressure. Decreasing the actual opening of the throttle valve will lead to an increase in exhaust pressure, while increasing the actual opening of the throttle valve will lead to a decrease in exhaust pressure. In a PID controller, the exhaust pressure of the system is adjusted to achieve the optimal value by adjusting the actual opening of the throttle valve.

[0080] Step 4: Changes in the system's return air temperature affect the thermal environment parameters of the passenger compartment, leading to changes in the temperature, humidity, and wind speed measured at various points on the human body. These parameters are collected from various points on the human body, and a weighted average is calculated. Values, if calculated in real time with weights If the value does not meet the convergence criterion, the energy-saving PID controller repeats steps 2 and 3 again based on real-time data until the PMV model calculated in step 2 is satisfied. The following conditions must be met:

[0081] ΔPMV≤0.001&|PMV-PMV target |≤0.005 (7)

[0082] Where ΔPMV represents the fluctuation, and PMV represents the weighted average. Value, PMV target for Target value.

[0083] This invention also discloses an energy-saving control system for an electric vehicle thermal management system based on a weighted PMV model, comprising:

[0084] The preset module sets preset parameters, ensuring that the exhaust pressure, return air temperature, and supply air temperature of the transcritical CO2 heat pump air conditioning system all reach the set values.

[0085] The energy-saving PID controller module is activated; the PID controller calculates the target PMV based on preset parameters. target Values ​​are calculated in real-time based on the collected data. Value, based on target PMV target and real-time weighting The target value for return air temperature is obtained through value calculation;

[0086] The return air temperature PID controller module adjusts the output compressor speed requirement based on the target return air temperature value, thereby adjusting the return air temperature and collecting data changes accordingly.

[0087] The loop output module is used to repeatedly execute the energy-saving PID controller module and the return air temperature PID controller module until real-time weighted calculation is performed. The value meets the set conditions.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An energy-saving control method for an electric vehicle thermal management system based on a weighted PMV model, characterized in that, Includes the following steps: Step 1: Set preset parameters and adjust the exhaust pressure, return air temperature, and supply air temperature of the transcritical CO2 heat pump air conditioning system in the electric vehicle to meet the preset parameters; collect real-time parameters inside the vehicle. Step 2: Activate the energy-saving PID controller; the energy-saving PID controller calculates the target PMV based on preset parameters. target The value is calculated based on real-time weighted values ​​collected from inside the vehicle. Value, based on target PMV target and real-time weighting The target value for return air temperature is obtained through value calculation; In step 2, In cooling mode, target PMV target The calculation formula is: PMV target = f a ( n,V,T env , m , P target , T in，target , T out,target )(1) In heating mode, target PMV target The calculation formula is: PMV target = f b ( n,V,T env , m , P target , T in，target , T out,target )(2) in, n For the number of passengers in the crew cabin, V For the internal volume of the crew cabin, T env For ambient temperature, m For energy efficiency rating, P target For the system exhaust pressure target value, T in，target For the target value of return air temperature and T out,target The target value for supply air temperature; Step 3: The return air temperature PID controller adjusts the output compressor speed according to the target value of the return air temperature, thereby adjusting the return air temperature, and the real-time parameters inside the vehicle change. Step 4: Repeat steps 2 and 3 until real-time weighting is achieved. The value meets the pre-set conditions.

2. The energy-saving control method for electric vehicle thermal management system based on weighted PMV model according to claim 1, characterized in that, In step 1, the preset parameters include the number of passengers in the passenger cabin. n Passenger cabin interior volume V Ambient temperature T env Energy efficiency rating m System exhaust pressure target value P target Target value for return air temperature T in，target and target value of supply air temperature T out,target .

3. The energy-saving control method for an electric vehicle thermal management system based on a weighted PMV model according to claim 1, characterized in that, In step 1, the exhaust pressure is made to reach the preset parameter by the exhaust pressure PID controller, the supply air temperature is made to reach the preset parameter by the supply air PID controller, and the return air temperature is made to reach the preset parameter by the return air PID controller.

4. The energy-saving control method for an electric vehicle thermal management system based on a weighted PMV model according to claim 3, characterized in that, The exhaust pressure PID controller controls the exhaust pressure by adjusting the opening of the electronic expansion valve, the supply air temperature PID controller adjusts the supply air temperature by adjusting the fan speed, and the return air temperature PID controller controls the return air temperature by adjusting the compressor speed.

5. The energy-saving control method for an electric vehicle thermal management system based on a weighted PMV model according to claim 1, characterized in that, In step 2, the real-time parameters inside the vehicle include the temperature of various parts of the human body, the air velocity inside the vehicle, and the humidity inside the vehicle.

6. The energy-saving control method for an electric vehicle thermal management system based on a weighted PMV model according to claim 1, characterized in that, In step 2, real-time weighting The formula for calculating the value is: （5） in, The PMV model values ​​are calculated for various parts of the human body. denoted by , where is the proportional weight of thermal sensation in different parts of the human body, and j represents the number of measurements taken from each part of the human body.

7. The energy-saving control method for an electric vehicle thermal management system based on a weighted PMV model according to claim 1, characterized in that, In step 2, the target value of the return air temperature must satisfy the following formula (6). If it does not satisfy the formula, the PI parameter of the energy-saving PID controller must be adjusted. （6） in, Tin,target Here, m represents the target return air temperature, m represents the energy efficiency rating, and n represents the number of passengers in the passenger compartment. Tenv For ambient temperature, V For the internal volume of the crew cabin, Ptarget For the system exhaust pressure target value, Tin, target The target value for return air temperature. Tout,target This is the target value for the supply air temperature.

8. The energy-saving control method for an electric vehicle thermal management system based on a weighted PMV model according to claim 1, characterized in that, In step 4, the pre-set conditions are: ≤0.005（7） in, For fluctuations, For weighted value, for Target value.

9. An energy-saving control system for an electric vehicle thermal management system based on a weighted PMV model for implementing the control method of claim 1, characterized in that, include: The preset module sets preset parameters and adjusts the exhaust pressure, return air temperature, and supply air temperature of the transcritical CO2 heat pump air conditioning system in electric vehicles to meet the preset parameters; it also collects real-time parameters inside the vehicle. The energy-saving PID controller module is used to activate the energy-saving PID controller; the energy-saving PID controller calculates the target PMV based on preset parameters. target The value is calculated based on real-time weighted values ​​collected from inside the vehicle. Value, based on target PMV target and real-time weighting The target value for return air temperature is obtained through value calculation; The return air temperature PID controller module is used to adjust the output compressor speed according to the return air temperature target value, thereby adjusting the return air temperature and causing real-time changes in the parameters inside the vehicle. The loop output module is used to repeatedly execute the energy-saving PID controller module and the return air temperature PID controller module until real-time weighted calculation is performed. The value meets the pre-set conditions.

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