Intelligent control method for heat dissipation of new energy commercial bus air conditioner

Abstract

The application relates to an intelligent control method for heat dissipation of a new energy commercial passenger vehicle air conditioner. The intelligent control method comprises the following steps: an intelligent controller in an air conditioner heat dissipation intelligent system collects supercooling degree x of an air conditioner refrigeration system through a vehicle-mounted local area network CAN bus communication port, collects air conditioner outlet temperature z and vehicle interior environment temperature y through an AD sampling port and a temperature sensor; the change delta x of the supercooling degree is calculated through the supercooling degree x, and then the supercooling degree change rate x' is calculated; the expected temperature difference value w is calculated through the air conditioner outlet temperature z and the vehicle interior environment temperature y, and then the temperature difference coefficient gamma is calculated; the minimum fan output air volume F max , the minimum fan output air volume F min , the vehicle interior environment and the air conditioner outlet temperature difference value w, and the predetermined h-level regulation amount of the fan are used to calculate the minimum fan output air volume change amount delta f of the electronic fan; the supercooling degree change rate, the expected temperature difference coefficient and the minimum air volume change amount are used to calculate the air volume required for air conditioner heat dissipation, so that the heat dissipation efficiency of the air conditioner heat dissipation system of the commercial passenger vehicle is improved, and energy consumption is reduced.

Description

Technical Field

[0001] This invention relates to an intelligent control method for air conditioning heat dissipation in new energy commercial buses. Background Technology

[0002] Onboard air conditioning is a standard feature in commercial buses, and its performance directly impacts the comfort of the passenger compartment and the vehicle's energy consumption. The air conditioning system itself is one of the most energy-intensive electrical devices in a vehicle, typically consisting of an air conditioning compressor, radiator, and electric fans. Besides the high energy consumption of the compressor, the energy consumption of the electric fans is also very high. A single electric fan typically has a rated current between 15A and 25A, and the number of fans installed varies from 2 to 8 depending on the vehicle's size and tonnage. Traditional commercial bus air conditioning systems are non-intelligent. When the air conditioning is activated, the controller simply closes the control circuit for the electric fans, causing all fans to run at full speed. This control method not only fails to meet the actual cooling needs of the air conditioning system under certain operating conditions but also results in significant energy consumption.

[0003] In response to the characteristics of new energy commercial buses, some manufacturers have improved the traditional air conditioning cooling system. When the system is operating, they limit the maximum speed of the electric fan by referencing the engine speed of a hybrid vehicle or the maximum output current of the low-voltage DC power supply in a pure electric vehicle. This limitation prevents excessive current from damaging the generator or DC / DC inverter when multiple electric fans operate at full power simultaneously. The engine speed is referenced to protect the generator because the vehicle's structure dictates that the generator is driven by the engine rotor to generate electricity. While this improvement adds intelligent control compared to traditional methods, it only addresses the issue of generator or DC / DC power supply failure; it doesn't truly solve the problems of excessive energy consumption in the onboard air conditioning system and the comfort of the in-vehicle environment. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent control method for the heat dissipation of air conditioning in new energy commercial buses, which can effectively improve the heat dissipation efficiency of the air conditioning system and reduce energy consumption.

[0005] To achieve the above objectives, the technical solution of the present invention is: an intelligent control method for air conditioning heat dissipation in commercial buses, providing an intelligent control system for air conditioning heat dissipation in new energy commercial buses, the method comprising the following steps:

[0006] Step 1. The intelligent controller in the intelligent air-conditioning heat dissipation control system respectively collects the subcooling degree values {x0, x1, x2, …}, the air outlet temperature values {z0, z1, z2, …}, and the vehicle interior environment temperature values {y0, y1, y2, …} corresponding to a series of consecutive sampling periods {T0, T1, T2, …}.

[0007] Step 2. Calculate the change in the subcooling degree value △x n =(x n - x n-1 ), n ∈ {1, 2, …}, and arrange the results of the subcooling degree change values in the time period as {△x0, △x1, △x2, …}. Screen the values in △x n , delete the numbers with △x n being 0, and retain the non-zero values of △x n . Then, compare these non-zero subcooling degree change values △x n and retain the corresponding subcooling degree values x n . Then, arrange the retained subcooling degree values x n-1 in the periodic order: {x0, x n , x a , x b , …}, a, b ∈ {1, 2, …}, where a < b, and the corresponding period values are {T0, T a , T b , …}, a, b ∈ {1, 2, …}, where a < b, where T a = a * T, T b = b * T; then, within the corresponding period {T0, T a , T b , …}, a, b ∈ {1, 2, …}, obtain the change rate x’ n =(x n - x m ) / T n , n, m ∈ {0, a, b, …}, where n > m and n, m are arranged in sequence in the set {0, a, b, …};

[0008] Step 3. Calculate the expected temperature difference values {△w0, △w1, △w2, …} between the vehicle interior environment temperature and the air outlet temperature corresponding to the period T n =(y n - z n ), n ∈ {0, 1, 2, …}. According to the formula γ n = △w n+1 / △w n+1 / △w n,n∈{0,1,2,…}where △w n When γ is 0 n+1 If the value is 0, calculate the expected temperature difference coefficient {γ1, γ2, γ3,…} for each cycle;

[0009] Step 4: The maximum airflow of the cooling electric fan is F. max Minimum air volume is F min The airflow output of the electric fan needs to vary in multiple levels. Therefore, if the fan airflow level is set to an integer value h > 0, then the minimum increment and decrement of the fan airflow is Δf = (F max -F min ) / h n , h∈{1,2,…}; To respond to the expected temperature difference between the ambient temperature and the outlet temperature, the minimum increment and decrement of the fan output airflow must be adjusted in real time according to the expected requirements. That is, in each cycle, the above minimum increment and decrement are multiplied by the temperature difference between the ambient temperature and the outlet temperature, Δf n =((F max -F min ) / h)*△w n h∈{1,2,…};

[0010] Step 5: Set the minimum threshold X min and maximum threshold X max Once the supercooling degree x ≤ X occurs min When overheating occurs, the electric fan is controlled to run at full speed to output maximum airflow, thus ensuring that the air conditioning system does not shut down. Conversely, if overcooling occurs (x > X), the system will shut down. max When this phenomenon occurs, the fan will stop rotating to ensure maximum energy saving. When the subcooling is within (X... min ,X max Within the interval, using formula f n = f n-1 + G*(1+γ n )*x' n *△f n Find the current period T for n∈{0,a,b,…} n The output air volume of the internal electric fan, where G is a negative constant coefficient with a value range of [-1, 0).

[0011] Compared to existing technologies, this invention has the following advantages: The method of this invention dynamically adjusts the speed of the electronic fan by collecting parameters such as air conditioning subcooling, in-vehicle ambient temperature, and air conditioning vent temperature, effectively solving the problems of air conditioning comfort and energy efficiency ratio in practical use of new energy commercial buses. The reason for calculating the air conditioning subcooling change rate is that it is necessary to judge the heat dissipation demand of the air conditioning system through the subcooling change rate. It is important to emphasize that the magnitude of the subcooling value of the air conditioning system does not accurately reflect the heat dissipation demand, but the rate of change of the subcooling value can reflect the heat dissipation demand of the refrigeration system to a certain extent. In addition to the important parameter of the subcooling change rate in the air conditioning system, we also need to address the early estimation of the subcooling change rate. This is because the characteristics of the electronic fan determine that the adjustment of the electronic fan speed has a lag time t1, and the conduction of heat dissipation also has a lag time t2. The t2 time is related to the internal physical structure of the air conditioning system, while the t1 time is related not only to the physical structure of the fan but also to the fan control method. Based on experience, t1 + t2 is approximately between 3 and 5 seconds. There are two methods for estimating lead time: one is to estimate based on experience, and the other is to refer to the source variables of air conditioning heat dissipation demand. This invention uses the source variables, ambient temperature and air outlet temperature parameters, to make the judgment. Attached Figure Description

[0012] Figure 1 This invention relates to an intelligent air conditioning heat dissipation control system.

[0013] Figure 2 This is a flowchart of the intelligent control method for air conditioner heat dissipation according to the present invention. Detailed Implementation

[0014] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0015] like Figure 1 As shown, this invention provides an intelligent control system for air conditioning cooling in commercial buses, including an air conditioning refrigeration system, an electric fan, an air conditioning outlet temperature sensor, an in-vehicle ambient temperature sensor, and an intelligent controller. The main component of the air conditioning refrigeration system is the air conditioning compressor. The intelligent controller collects the subcooling of the air conditioning system through the vehicle's CAN bus communication port, and collects the air conditioning outlet temperature and the in-vehicle ambient temperature through an AD sampling port and temperature sensors. Then, based on changes in subcooling, air conditioning outlet temperature, and in-vehicle ambient temperature, the intelligent controller determines the required heat dissipation of the air conditioning cooling system, and subsequently calculates the required airflow from the electric fan. Next, the intelligent controller converts the required airflow into the required fan speed. Finally, the intelligent controller adjusts the fan speed via PWM output.

[0016] like Figure 2As shown, this invention is an intelligent control method for heat dissipation in commercial buses, which includes the following steps:

[0017] (1) The intelligent controller continuously collects the subcooling degree y of the air conditioning system via the CAN bus at a cycle of T. The collected signal is transmitted from the air conditioning system to the intelligent controller via the SAE J1939 protocol of the vehicle local area network CAN bus. The transmission message ID is the hexadecimal value 0x18FF0E9D, and the priority is 0b110, which is a low priority in the vehicle bus message. The transmission method is cyclic transmission with a transmission cycle of 500 milliseconds. The reason for using a low priority and a long transmission cycle is, on the one hand, to ensure that the load of the vehicle local area network CAN bus does not exceed 40%, and on the other hand, because the frequency of the air conditioning subcooling degree change is mainly between 0.2Hz and 1.5Hz, so there is no need to use an excessively high frequency for collection. The subcooling degree value of the air conditioning refrigeration system is generally higher than 0℃ and lower than 100℃. However, in order to ensure the maximum applicability of the signal definition range, the 6th and 7th bytes of the message are used to transmit the signal value and the signal value range is set between -40℃ and 210℃. According to the accuracy requirements of the subcooling degree value of the air conditioning cooling system, the resolution of the message signal is set to 0.1℃ / bit.

[0018] (2) The intelligent controller collects the air conditioning vent temperature z and the central ambient temperature y inside the vehicle through the AD sampling interface of the main chip and the external temperature sensor. In order to ensure the accuracy of the collected data, 4 to 6 temperature sensors can be installed in the central ambient temperature of the vehicle according to the geometric orientation. Finally, the central ambient temperature k can be the average value of all temperature sensors.

[0019] (3) The intelligent controller corresponds to multiple sampling periods {T0, T... 1, T 2, …}, the subcooling values ​​of the air conditioning system were collected respectively from {x0, x 1, x 2, …}, the air conditioner outlet temperature value is {z0, z 1, z 2, …}, the ambient temperature inside the vehicle is {y0, y 1, y 2, …}

[0020] (4) Using the formula △x n =( x n - x n-1 The change in supercooling value Δx is calculated for n∈{1,2,…}. n The results of supercooling variation values ​​are arranged according to time period {Δx0, Δx}. 1, △x 2, …}。 For △x n Filter the values ​​in the data and delete △x. nThe number that is 0, retain Δx n The non-zero numerical values. Then compare these non-zero subcooling degree change values Δx n Retain the corresponding subcooling degree values x n-1 , and then arrange the retained subcooling degree values x n in chronological order: {x0, x a, x b, …}, a, b ∈ {1, 2, …} where a < b, and the corresponding cycle values are {T0, T a, T b, …}, a, b ∈ {1, 2, …} where a < b, where T a = a * T, T b = b * T.

[0021] (5)According to the above-screened subcooling degree values, then within the corresponding cycle {T0, T a, T b, …}, a, b ∈ {1, 2, …}, obtain the change rate x ’ n =(x n - x m ) / T n , n, m ∈ {0, a, b…} where n > m and n, m are arranged in sequence in the set {0, a, b…}. The reason for calculating the change rate of the air conditioner's subcooling degree is that it is necessary to judge the heat dissipation demand of the air conditioner refrigeration system through the change rate of the subcooling degree. It should be emphasized here that: the magnitude of the subcooling degree value of the air conditioner refrigeration system cannot accurately reflect the heat dissipation demand, but the speed of change of the subcooling degree value can, to a certain extent, reflect the heat dissipation demand of the refrigeration system.

[0022] (6)In addition to the important parameter of the change rate of the subcooling degree in the air conditioner refrigeration system, we also need to solve the advance estimation of the change rate of the subcooling degree. This is because the characteristics of the electronic fan determine that there is a lag time t1 for the adjustment of the electronic fan speed, and at the same time, there is also a lag time t2 for the conduction of the heat dissipation temperature. The t2 time is related to the internal physical structure of the air conditioner refrigeration system. The t1 time is not only related to the physical structure of the fan but also related to the fan control method. According to experience feedback, t1 + t2 is approximately between 3 and 5 seconds. There are two methods for estimating the advance amount. One is to estimate through experience, and the other is to refer to the source of the air conditioner's heat dissipation demand. Here we adopt the source parameter estimation method: First, calculate the expected temperature difference value {Δw0, Δw n =(y n - z n ), n ∈ {0, 1, 2, …} between the in-vehicle ambient temperature and the outlet air temperature corresponding to the cycle T n {Δw0, Δw 1, Δw2, …}. According to the formula γ n+1 =△w n+1 / △w n ,n∈{0,1,2,…}where △w n When γ is 0 n+1 If the value is equal to 0, calculate the expected temperature difference coefficient {γ1, γ} for each cycle. 2, γ 3, …}. This coefficient, when added to the rate of change of subcooling, gives the lead time for airflow demand.

[0023] (7) Due to the inherent characteristics of an electric fan, its maximum airflow is F. max Minimum air volume is F min If the fan airflow level is set to an integer value h > 0, then the minimum increment and decrement of the fan airflow is Δf = (F max -F min ) / h n h∈{1,2,…}. To respond to the expected temperature difference between the ambient temperature and the outlet temperature, the minimum increment and decrement of the fan output airflow must be adjusted in real time according to the expected requirements. That is, the aforementioned minimum increment and decrement are multiplied by the temperature difference between the ambient temperature and the outlet temperature, Δf. n =((F max -F min ) / h)*△w n , h∈{1,2,…}.

[0024] (8) Set a minimum threshold X based on the characteristics of the air conditioner itself. min and maximum threshold X max Once the supercooling degree x ≤ X occurs min When overheating occurs, the electric fan is controlled to run at full speed to output maximum airflow, thus ensuring that the air conditioning system does not shut down. Conversely, if overcooling occurs (x > X), the system will shut down. max When this phenomenon occurs, the fan will stop rotating to ensure maximum energy savings. Setting minimum and maximum thresholds is also important because other interfering parameters exist in the air conditioning system, such as condensation degree. Under the interference of unexpected parameters, some extreme cases can be reflected in the magnitude of subcooling. Therefore, we set maximum and minimum thresholds to ensure the normal operation of the air conditioning system.

[0025] (9) When the supercooling is in (X) min ,X max Within the interval, using formula f n = f n-1 + G*(1+γ n )*x ’ n *△f nFind the current period T for n∈{0,a,b,…} n The output air volume of the internal electric fan, where G is a negative constant coefficient with a value range of [-1, 0). This negative constant coefficient is related to the air conditioning system, which can be calibrated when the air conditioning system leaves the factory.

[0026] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. An intelligent control method for air conditioning heat dissipation in a new energy commercial bus, characterized in that, A smart control system for air conditioning and heat dissipation in a new energy commercial bus is provided, including a smart controller and an electronic fan, an air conditioning system, and a temperature sensor connected to the smart controller. The method includes the following steps: Step 1: The intelligent controller collects the subcooling degree x of the air conditioning system through the vehicle local area network CAN bus communication port, and collects the air conditioning outlet temperature z and the in-vehicle ambient temperature y through the AD sampling port and temperature sensor. Step 2: Calculate the change in subcooling Δx using the subcooling degree x, and then determine the rate of change of subcooling x'; Step 3: Calculate the expected temperature difference w using the air conditioner vent temperature z and the in-vehicle ambient temperature y, and then determine the temperature difference coefficient γ. Step 4: Based on the maximum output airflow F of the electric fan max Minimum output air volume F min The minimum airflow change Δf required by the electric fan is calculated based on the temperature difference w between the vehicle interior environment and the air conditioning vents, as well as the fan's predetermined h-level adjustment. Step 5: Calculate the air volume required for air conditioning heat dissipation based on the subcooling change rate, expected temperature difference coefficient, and minimum air volume change. In step 1, the intelligent controller collects the subcooling value of the air conditioning cooling system {x0, x1, x2, …}, the air outlet temperature value {z0, z1, z2, …}, and the in-vehicle ambient temperature value {y0, y1, y2, …} for multiple consecutive sampling periods {T0, T1, T2, …}. In step 2, the change in the degree of undercooling Δx n is calculated by the formula Δx n =(x n-1 - x n ), where n ∈ {1, 2, …}. The results of the changes in the degree of undercooling are arranged according to the time period as {Δx0, Δx1, Δx2, …}; the values in Δx n are screened, the numbers with Δx n equal to 0 are deleted, and the non-zero values of Δx n are retained; then, the corresponding degrees of undercooling are retained according to the non-zero changes in the degree of undercooling Δx n , and the retained degrees of undercooling x n are arranged in order of the period: {x0, x a , x b , …}, where a, b ∈ {1, 2, …} and a < b, and the corresponding period values are {T0, T a , T b , …}, where a, b ∈ {1, 2, …} and a < b, T a =a*T, T b =b*T; then, the change rate x’ a of the air conditioner's degree of undercooling is obtained within the corresponding period {T0, T b , …}, where a, b ∈ {1, 2, …} as x’ n =(x n - x m ) / T n , where n, m ∈ {0, a, b, …} and n > m and n, m are arranged in sequence in the set {0, a, b, …}; In step 3, the formula △w is used. n =( y n - z n ), n∈{0,1,2,…} calculate the period T n The expected temperature difference between the corresponding in-vehicle ambient temperature and the air vent temperature {△w0, △w1, △w2, …}; according to the formula γ n+1 =△w n+1 / △w n ,n∈{0,1,2,…}where △w n When γ is 0 n+1 If the value is 0, calculate the expected temperature difference coefficient {γ1, γ2, γ3, …} for each cycle; In step 4, the maximum airflow of the cooling fan is F. max Minimum air volume is F min The airflow output of the electric fan needs to be varied in multiple stages. Therefore, the fan airflow level is set to an integer value where h > 0. The minimum increment and decrement of the fan airflow is then Δf = (F... max -F min ) / h n , h∈{1,2,…}; To respond to the expected temperature difference between the ambient temperature and the outlet temperature, the minimum increment and decrement of the fan output airflow must be adjusted in real time according to the expected requirements. That is, in each cycle, the above minimum increment and decrement are multiplied by the temperature difference between the ambient temperature and the outlet temperature, Δf n =((F max -F min ) / h)*△w n h∈{1,2,…}; In step 5, a minimum subcooling threshold X is set. min and the maximum threshold of supercooling X max Once the supercooling degree x ≤ X occurs min When the phenomenon occurs, the electric fan is controlled to run at full speed to output maximum airflow, thereby ensuring that the air conditioning system does not overheat and shut down; conversely, if overcooling occurs (x>X), the system will shut down. max When this phenomenon occurs, the fan will be stopped to ensure maximum energy saving; When the supercooling is in (X) min ,X max Within the interval, using formula f n = f n-1 + G*(1+γ n )*x' n *Calculate the current period T from △f,n∈{0,a,b,…} n The output air volume of the internal electric fan, where G is a negative constant coefficient with a value range of [-1, 0).

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