System temperature cross-domain thermal management method of power unit

Abstract

The invention belongs to the technical field of vehicle power system thermal management control, and particularly relates to a system temperature cross-domain thermal management method of a power unit, which comprises system temperature loop parameter setting, temperature drop strategy design based on temperature cross-level and consumption reduction strategy design based on temperature cross-level. In the acting process of the thermal management system, firstly, a heat dissipation loop needs to carry out temperature positioning and temperature cross-domain judgment according to temperature ring temperature domain interval setting. And according to the temperature rise regulation stage or the temperature drop regulation stage of the system, the heat management system comprehensively regulates the rotating speed and response time of the fan in combination with the initial temperature interval and the temperature cross-domain level, so that efficient heat dissipation of the fan with the temperature cross-domain change in the operation process is met, and normal operation of the system is guaranteed. Meanwhile, according to real-time changes of the temperature field, the heat management system reduces the rotating speed of the fan in time so as to reduce the energy consumption requirement of the system, and the fuel economy and the energy utilization rate of the vehicle are effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of thermal management control technology for vehicle power systems, and specifically relates to a method for cross-domain thermal management of system temperature of a power unit, which mainly involves multi-loop control processes such as system thermal field distribution within the vehicle power unit, overall rapid heat regulation process, and comprehensive and efficient utilization of energy consumption. During the operation of the vehicle-mounted power unit, there are different heat dissipation circuits, and different circuits correspond to different components and temperature field change processes, but the temperature change process of multiple circuits does not change gradually. Therefore, in the actual thermal field temperature adjustment process, thermal management needs to be efficiently judged based on temperature changes and the overall change process of the multi-circuit temperature field. Under the premise of temperature index judgment, the system adjustment process can be dynamically realized, thereby completing the temperature field thermal management process of the power unit. Background Art

[0002] The vehicle power unit itself is composed of different temperature loops (i.e. temperature circuits), and different temperature loops correspond to different key components. However, different temperature loops dissipate heat through the same cooling unit at the thermal management center, thereby completing the centralized cooling of the system cooling circuit. The central cooling unit actuator corresponds to the system cooling fan, and the system thermal management is to complete the real-time adjustment of the fan speed through the specific temperature change process of different circuits, thereby completing the heat dissipation control process of the system temperature.

[0003] In the process of changing the temperature field of multiple circuits of the power unit, the first thing to do is to meet its efficient heat dissipation needs. Since the dynamic temperature change of the specific circuit of the power unit does not change gradually, during the actual operation of the system, the circuit temperature may rise from low temperature to warning temperature in a very short time, spanning multiple temperature ranges and levels. Therefore, in the actual temperature adjustment process, it is necessary to respond to the demand according to the temperature change process and range. At this time, the fan should follow the speed response within the effective time, so as to complete the dynamic change and adjustment process of the temperature range.

[0004] In addition, thermal management does not mean that the system thermal management problem can be solved by simply turning the fan to the maximum speed without constraints to meet the heat dissipation requirements. Long-term high-speed operation of the fan will have a significant impact on the performance and life of the fan itself. While meeting the overall heat dissipation requirements, the thermal management system also needs to carry out online adaptive adjustment of the fan speed according to actual needs, so as to reduce the fan speed in time under low-heat or cold conditions to ensure the stability of the system heat and temperature field, thereby reducing the system operating power as much as possible and ensuring the high energy utilization requirements during vehicle driving.

[0005] Traditional thermal management strategies are mainly based on fluid dynamic analysis of temperature fields, and comprehensive system adjustments are made based on the overall distribution and specific characteristics of the thermal field. With the increase in vehicle components, the temperature loop also increases synchronously. Previous research and patents have not involved much in the quantitative division of multiple temperature fields, fan speed adjustment under the demand for rapid temperature rise response, and system temperature adjustment process under the coupling of multiple temperature fields. At the same time, in the process of temperature adjustment, how to effectively combine the minimum energy principle into the design process of comprehensive temperature field regulation and control strategy is also one of the problems that need to be solved in online temperature adjustment. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] The technical problem to be solved by the present invention is: how to provide a system temperature cross-domain thermal management method for a power unit, so as to realize the system temperature field positioning and rapid heat dissipation system requirements during the operation of the power unit in a high-heat environment, and the system energy consumption rapid reduction system requirements under the low-heat and high-speed operation conditions of the heat dissipation system. The control method grids the temperature fields corresponding to different temperature loops of the system, thereby realizing the rapid temperature adjustment process during the alternating transformation of multiple fields, thereby meeting the system's rapid and efficient heat dissipation requirements.

[0008] (II) Technical solution

[0009] In order to solve the above technical problems, the present invention provides a system temperature cross-domain thermal management method for a power unit, and the system temperature cross-domain thermal management method for a power unit comprises:

[0010] Step 1: System temperature loop parameter setting;

[0011] Step 2: Design of temperature reduction strategy based on temperature span level;

[0012] Step 3: Design of energy saving strategy based on temperature span level.

[0013] Wherein, in step 1, during the process of setting the system temperature loop parameters, specific temperature loop parameter settings are carried out as follows:

[0014] In the integrated chassis system, the thermal management system consists of a high-temperature loop, a low-temperature loop and a medium-temperature loop. Since the engine temperature is relatively high, the engine and its controller loop are defined as a high-temperature loop; the generator temperature is relatively low, so the generator and its controller loop are defined as a low-temperature loop; the on-board battery pack loop in the chassis system is an independent cooling loop, defined as a medium-temperature loop, which includes:

[0015] The initial temperature of the high temperature ring is T U , its range of change corresponds to: H1=[0,t u1 ]、H2=(t u1 ,tu2 ]、H3=(t u2 ,t u3 ]、H4=(t u3 ,t u4 ]; meet the conditions: 0 <t u1 <t u2 <t u3 <t u4 ;

[0016] The initial temperature of the low temperature ring is T B , its range of change corresponds to: B1=[0,t b1 ]、B2=(t b1 ,t b2 ]、B3=(t b2 ,t b3 ]、B4=(t b3 ,t b4 ]; meet the conditions: 0 <t b1 <t b2 <t b3 <t b4 ;

[0017] The initial temperature of the medium temperature ring is T M , its range of change corresponds to: M1=[0,t m1 ]、M2=(t m1 ,t m2 ]、M3=(t m2 ,t m3 ]、M4=(t m3 ,t m4 ]; meet the conditions: 0 <t m1 <t m2 <t m3 <t m4 ;

[0018] According to the temperature range of the temperature ring, the speed of the cooling fan in the thermal management system changes synchronously, and it changes dynamically and adaptively between 0 and 5500 rpm at different rates to ensure the normal operation of each subsystem and the stable performance maintenance;

[0019] Set the above H1, B1, M1 as the first temperature range, H2, B2, M2 as the second temperature range, H3, B3, M3 as the third temperature range, H4, B4, M4 as the fourth temperature range; in the actual cooling fan speed control process, assume that the actual speed of the current fan is n a (Unit: rpm), adjust the fan speed according to the temperature change n (Unit: rpm / s) to adjust the target speed n g (Unit: rpm), the tolerance range is [ng -5,n g +5].

[0020] Wherein, in the step 1, when carrying out specific temperature loop parameter setting, the system temperature cross-domain determination process is carried out as follows:

[0021] Due to differences in working and operating conditions, the temperature changes of different subsystems of the chassis are relatively random and may span multiple temperature ranges in a short period of time. In order to respond to temperature changes, the thermal management system needs to respond to the fan speed according to the actual temperature changes. At this time, it is necessary to quantify the temperature changes.

[0022] The temperature variation ranges of each temperature ring of high, medium and low and the corresponding temperature cross-domain variation levels are shown in Table 1 below;

[0023] Table 1 System temperature rise cross-domain determination

[0024]

[0025] According to the cross-domain level of system temperature, the speed increase rate of the cooling fan is further adjusted and controlled to achieve overall control of the system temperature.

[0026] Wherein, in step 2, in the temperature reduction strategy design process based on the temperature span level, a low temperature span temperature reduction speed regulation strategy design process is carried out:

[0027] According to the temperature crossing level, the fan speed is adjusted during the system temperature rising process. n Real-time regulation is performed to meet the dynamic cooling requirements of the actual chassis system;

[0028] In the low temperature range, if the initial temperature range of each temperature ring is the highest of the first temperature range, then in the process of temperature ring temperature changing across the region, it is assumed that the change time is δ f (s), which corresponds to the fan speed adjustment speed v n Need to be in δ f According to the target speed n g Respond promptly to temperature changes. The specific corresponding relationship is:

[0029]

[0030] In the low temperature range, if the initial temperature range of each temperature ring is the highest in the second temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , which corresponds to the fan speed adjustment speed v in claim 2 n Need to be in δ f According to the target speed value ng Respond promptly to temperature changes. The specific corresponding relationship is:

[0031]

[0032] In the low temperature range, if the initial temperature range of each temperature ring is up to the third temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f Target speed n within time g Respond promptly to temperature changes. The specific corresponding relationship is:

[0033]

[0034] Wherein, in the step 2, in the temperature reduction strategy design process based on the temperature span level, a medium temperature span temperature reduction speed regulation strategy design process is carried out:

[0035] In the middle temperature range, no matter the initial temperature is in the first temperature range or the second temperature range, the temperature ring temperature changes across regions at this time, and the cooling fan needs to respond in time; in the temperature cross-domain change time δ f Calculate the initial high temperature ring temperature T U , low temperature ring temperature T B and medium temperature ring temperature T M The corresponding temperature change rate η U , η B , η M , = then we have the following formula:

[0036]

[0037] Where, T Umax , T Bmax and T Mmax are the maximum temperatures of each temperature ring after the temperature changes across the domain;

[0038] Based on this, the maximum value η of the temperature change rate is extracted max and the minimum value η min They correspond to:

[0039]

[0040] Fan speed adjustment speed v n The maximum temperature change rate η max , minimum value η min , and the cross-domain change time δ f and actual speed n a, target speed n g The dynamic changes of the , the specific corresponding relationship is:

[0041]

[0042] In the formula, λ u is the temperature variation coefficient, which is related to the maximum temperature change rate η max With the minimum value η min The specific relationship is:

[0043]

[0044] Wherein, in step 2, in the temperature reduction strategy design process based on the temperature span level, a high temperature span temperature reduction speed regulation strategy design process is carried out:

[0045] In the high temperature range, the initial temperature range of each temperature ring is the first temperature range, but the temperature of the temperature ring varies greatly across regions. At this time, the cooling system needs to speed up in time to respond to such a drastic temperature change. Assuming that the temperature cross-domain change time is δ f , calculate δ f The maximum temperature difference corresponding to each temperature ring after time is:

[0046] T D =max[(T Umax -T U ),(T Bmax -T B ),(T Mmax -T M )]

[0047] In δ f During this time, the fan speed is adjusted to speed v n According to the maximum temperature difference T D And the actual speed n a , target speed n g Respond promptly to temperature changes. The specific corresponding relationship is:

[0048]

[0049] Wherein, in step 3, in the process of designing the energy-saving strategy based on the temperature span level, a low-temperature span speed reduction strategy design process is carried out:

[0050] According to the temperature crossing level, the fan speed response speed v of the system cooling fan when the temperature drops during the temperature drop process n Conduct real-time control to reduce the actual energy consumption demand of the chassis system;

[0051] In the low temperature range, if the initial temperature range of each temperature ring is up to the fourth temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f Within the time, according to the target speed n g The dynamic changes of the temperature should be responded to in time. The specific corresponding relationship is:

[0052]

[0053] In the low temperature range, if the initial temperature range of each temperature ring is up to the third temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the fan speed adjustment speed v n Need to be in δ f Within the time, according to the weighted target speed n g The dynamic changes of the temperature should be responded to in time. The specific corresponding relationship is:

[0054]

[0055] In the low temperature range, if the initial temperature range of each temperature ring is the highest in the second temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f Respond promptly to temperature changes within a certain period of time. The specific corresponding relationship is:

[0056]

[0057] Wherein, in step 3, during the consumption reduction strategy design process based on the temperature span level, a medium temperature span speed reduction strategy design process is carried out:

[0058] In the middle temperature range, no matter the initial temperature is in the third or fourth temperature range, the cross-region temperature change of the temperature ring at this time shows obvious fluctuations, and the cooling fan needs to respond in time; in the temperature cross-domain change time δ f Calculate the initial high temperature ring temperature T U , low temperature ring temperature T B and medium temperature ring temperature T M The corresponding temperature change rate η U , η B , η M , then we have the following formula:

[0059]

[0060] Where, T Umin , T Bmin and T Mmin are the minimum temperatures of each temperature ring after the temperature changes across the domain;

[0061] Based on this, the maximum value η of the temperature change rate is extracted max and the minimum value η min Corresponding to respectively, we have:

[0062]

[0063] Corresponding fan speed adjustment speed v n The maximum temperature change rate η max , minimum value η min , and the cross-domain change time δ f and actual speed n a , target speed n g The dynamic changes of the , the specific corresponding relationship is:

[0064]

[0065] In the formula, λ d is the speed reduction coefficient, which is related to the maximum temperature change rate η max With the minimum value η min The specific relationship is:

[0066]

[0067] Wherein, in step 3, in the process of designing the energy-saving strategy based on the temperature span level, a high-temperature span speed reduction strategy design process is carried out:

[0068] In the high temperature range, the initial temperature range of each temperature ring is the fourth temperature range, but the temperature of the temperature ring varies greatly across regions. At this time, the cooling system needs to slow down in time to reduce the energy consumption demand of the system, so as to ensure that the system continues to operate at a higher efficiency. Assuming that the temperature cross-domain change time is δ f , calculate δ f The maximum temperature difference corresponding to each temperature ring after a certain period of time is calculated as follows:

[0069] T D =max[(T Umax -T U ),(T Bmax -T B ),(T Mmax -T M )]

[0070] In δ fDuring this time, the fan speed is adjusted to speed v n要 According to the maximum temperature difference T D Respond promptly to temperature changes. The specific corresponding relationship is:

[0071]

[0072] (III) Beneficial effects

[0073] Compared with the prior art, the present invention proposes a cross-domain thermal management method for the system temperature of the power unit based on the temperature field change process of the vehicle-mounted power unit system. The method makes a comprehensive reference based on the initial positioning of the temperature range of different circuits, the temperature crossing level, the temperature change value and the change rate, and determines the specific target speed range and adjustment time based on the state judgment, thereby completing the rapid adjustment of the system temperature under different temperature domain crossing conditions, and realizing the rapid heat dissipation of multiple temperature fields of the whole vehicle and the rapid adjustment control process design of energy consumption response. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 Schematic diagram of the principle of system temperature cross-domain thermal management method.

[0075] Figure 2 Schematic diagram of the system temperature rise speed control strategy.

[0076] Figure 3 Schematic diagram of the system's energy-saving and speed-regulating control strategy. DETAILED DESCRIPTION

[0077] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0078] In order to solve the above technical problems, the present invention provides a system temperature cross-domain thermal management method for a power unit, and the system temperature cross-domain thermal management method for a power unit comprises:

[0079] First, the temperature loop parameters are set according to the temperature loops of the power unit, and the three loops of high temperature loop, low temperature loop and medium temperature loop are obtained. Secondly, different temperature loops are divided into specific temperature change ranges according to their own adaptive working temperatures, thereby completing the grid division of temperature. Finally, according to the differences in the working conditions and operating conditions of the power unit, the temperature change ranges of high, medium and low temperature loops and the corresponding temperature cross-domain range change levels are specified, as follows Figure 1 shown.

[0080] On this basis, according to the initial temperature range and the temperature cross-region change, a temperature reduction strategy based on the temperature span level is developed and designed. By comparing the temperature span level and the initial temperature range, the fan target speed n is used to determine the fan target speed. gand action time δ f demand, thereby achieving the fan speed response speed v during the system temperature rise process n Real-time regulation to meet the dynamic heat dissipation requirements of the actual chassis system. This process mainly includes three main parts: low-temperature cross-cooling speed regulation strategy, medium-temperature cross-cooling speed regulation strategy and high-temperature cross-cooling speed regulation strategy. The specific regulation process is as follows Figure 2 shown.

[0081] At the same time, according to the temperature span level, the energy saving strategy based on the temperature span level is developed and designed. By comparing the temperature span level and the initial temperature range, the judgment is made and the fan target speed n is completed. g and action time δ f Demand positioning, so that the fan speed response speed v when the system cooling fan slows down during the temperature drop process can be n Real-time regulation is performed to reduce the actual energy consumption demand of the chassis system. This process mainly includes three main parts: low temperature cross speed reduction strategy, medium temperature cross speed reduction strategy and high temperature cross speed reduction strategy. The specific adjustment process is as follows Figure 3 shown.

[0082] Example 1

[0083] The stable operation of the vehicle integrated chassis system of this embodiment depends on the rapid adjustment of the thermal management system, and the thermal management system identifies the temperature of the subsystems within the integrated chassis system to obtain reliable temperature values, thereby achieving effective regulation at precise temperatures. During the adjustment process, the thermal management system needs to adjust the cooling fan speed change rate according to the temperature changes of the specific temperature ring. In the actual operation process, if the temperature of the temperature ring changes across regions, the thermal management system at this time cannot simply increase the fan speed to improve the heat dissipation efficiency. At this time, it is necessary to adopt a reasonable adjustment strategy to adjust the fan response rate to achieve system temperature control under the following effect.

[0084] Step 1: System temperature loop parameter setting

[0085] 1.1 Temperature loop parameter setting

[0086] In the integrated chassis system, the thermal management system consists of a high temperature loop, a low temperature loop and a medium temperature loop. Since the engine temperature is relatively high, the engine and its controller loop are defined as a high temperature loop; the generator temperature is relatively low, and the generator and its controller loop are defined as a low temperature loop; the on-board battery pack loop in the chassis system is an independent cooling loop, defined as a medium temperature loop, which includes:

[0087] The initial temperature of the high temperature ring is T U , its range of change corresponds to: H1=[0,t u1 ]、H2=(tu1 ,t u2 ]、H3=(t u2 ,t u3 ]、H4=(t u3 ,t u4 ]; meet the conditions: 0 <t u1 <t u2 <t u3 <t u4 ;

[0088] The initial temperature of the low temperature ring is T B , its range of change corresponds to: B1=[0,t b1 ]、B2=(t b1 ,t b2 ]、B3=(t b2 ,t b3 ]、B4=(t b3 ,t b4 ]; meet the conditions: 0 <t b1 <t b2 <t b3 <t b4 ;

[0089] The initial temperature of the medium temperature ring is T M , its range of change corresponds to: B1=[0,t m1 ]、M2=(t m1 ,t m2 ]、M3=(t m2 ,t m3 ]、M4=(t m3 ,t m4 ]; meet the conditions: 0 <t m1 <t m2 <t m3 <t m4 .

[0090] According to the temperature range of the different temperature rings, the speed of the cooling fan in the thermal management system changes synchronously, and it adaptively and dynamically changes at different rates between 0 and 5500 rpm to ensure the normal operation of each subsystem and stable performance maintenance.

[0091] Set the above H1, B1, M1 as the first temperature range, H2, B2, M2 as the second temperature range, H3, B3, M3 as the third temperature range, H4, B4, M4 as the fourth temperature range. In the actual cooling fan speed control process, assuming that the actual speed of the current fan is n a (rpm), increase the fan speed according to the temperature change n (rpm / s) to adjust the target speed n g(rpm), the tolerance range is [n g -5,n g +5].

[0092] 1.2 System temperature cross-domain determination

[0093] Due to differences in working and operating conditions, the temperature changes of different subsystems of the chassis are relatively random, and may span multiple temperature ranges in a short period of time. In order to respond to temperature changes, the thermal management system needs to respond to the fan speed according to the actual temperature changes. At this time, it is necessary to quantify the temperature changes.

[0094] The temperature variation ranges of the high, medium and low temperature rings and the corresponding temperature cross-domain range variation levels are shown in Table 1 below.

[0095] Table 1 System temperature rise cross-domain determination

[0096]

[0097] According to the cross-domain level of system temperature, the speed increase rate of the cooling fan can be further adjusted and controlled to achieve overall control of the system temperature.

[0098] Step 2: Temperature reduction strategy based on temperature span level

[0099] Depending on the temperature level, the fan speed response speed v can be adjusted during the system temperature rise process. n Real-time regulation to meet the dynamic heat dissipation needs of the actual chassis system.

[0100] 2.1 Low temperature cross-cooling speed regulation strategy

[0101] In the low temperature range, if the initial temperature range of each temperature ring is the highest of the first temperature range, then in the process of temperature ring temperature changing across the region, it is assumed that the change time is δ f (s), the corresponding fan speed adjustment speed v n Need to be in δ f According to the target speed value n g Respond promptly to temperature changes. The specific corresponding relationship is:

[0102]

[0103] In the low temperature range, if the initial temperature range of each temperature ring is the highest in the second temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f According to the target speed value ng Respond promptly to temperature changes. The specific corresponding relationship is:

[0104]

[0105] In the low temperature range, if the initial temperature range of each temperature ring is up to the third temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f According to the target speed value n g Respond promptly to temperature changes. The specific corresponding relationship is:

[0106]

[0107] 2.2 Medium temperature cross-cooling speed regulation strategy

[0108] In the middle temperature range, no matter the initial temperature is in the first temperature range or the second temperature range, the temperature ring temperature changes across regions at this time and there are obvious fluctuations. At this time, the cooling fan needs to respond in time. f Calculate the initial high temperature ring temperature T U , low temperature ring temperature T B and medium temperature ring temperature T M The corresponding temperature change rate is as follows:

[0109]

[0110] Where, T Umax , T Bmax and T Mmax They are the maximum temperatures of each temperature ring after the temperature changes across the domain.

[0111] Based on this, the maximum value η of the temperature change rate is extracted max and the minimum value η min Corresponding to respectively, we have:

[0112]

[0113] Corresponding fan speed adjustment speed v n The maximum temperature change rate η max , minimum value η min , and the cross-domain change time δ f and actual speed n a , target speed value n g The dynamic changes of the , the specific corresponding relationship is:

[0114]

[0115] In the formula, λ u is the temperature variation coefficient, which is related to the maximum temperature change rate η max With the minimum value η min The specific relationship is:

[0116]

[0117] 2.3 High temperature cross-cooling speed regulation strategy

[0118] In the high temperature range, the initial temperature range of each temperature ring is the first temperature range, but the temperature of the temperature ring varies greatly across regions. At this time, the cooling system needs to speed up in time to respond to such a dramatic temperature change. Assume that the temperature cross-domain change time is δ f , calculate δ f The maximum temperature difference corresponding to each temperature ring after time is:

[0119] T D =max[(T Umax -T U ),(T Bmax -T B ),(T Mmax -T M )]

[0120] In δ f The fan speed is adjusted accordingly within the time v n , according to the maximum temperature difference T D And the actual speed n a , target speed value n g Respond promptly to temperature changes. The specific corresponding relationship is:

[0121]

[0122] Step 3: Energy saving strategy based on temperature span level

[0123] According to the temperature crossing level, the fan speed response speed v of the system cooling fan when the temperature drops can be adjusted. n Carry out real-time regulation to reduce the actual energy consumption demand of the chassis system.

[0124] 3.1 Low temperature cross-speed reduction strategy

[0125] In the low temperature range, if the initial temperature range of each temperature ring is up to the fourth temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δf Within the time, according to the target speed value n g The dynamic changes of the temperature should be responded to in time. The specific corresponding relationship is:

[0126]

[0127] In the low temperature range, if the initial temperature range of each temperature ring is up to the third temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f Within the time, according to the target speed value n g The dynamic changes of the temperature should be responded to in time. The specific corresponding relationship is:

[0128]

[0129] In the low temperature range, if the initial temperature range of each temperature ring is the highest in the second temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f Respond promptly to temperature changes within a certain period of time. The specific corresponding relationship is:

[0130]

[0131] 3.2 Medium temperature speed reduction strategy

[0132] In the middle temperature range, no matter the initial temperature is in the third or fourth temperature range, the temperature ring temperature changes across regions at this time show obvious fluctuations, and the cooling fan needs to respond in time. f Calculate the initial high temperature ring temperature T U , low temperature ring temperature T B and medium temperature ring temperature T M The corresponding temperature change rate is as follows:

[0133]

[0134] Where, T Umin , T Bmin and T Mmin They are the minimum temperatures of each temperature ring after the temperature changes across the domain.

[0135] Based on this, the maximum value η of the temperature change rate is extracted max and the minimum value η min Corresponding to respectively, we have:

[0136]

[0137] Corresponding fan speed adjustment speed v n The maximum temperature change rate η max , minimum value η min , and the cross-domain change time δ f and actual speed n a , target speed value n g The dynamic changes of the , the specific corresponding relationship is:

[0138]

[0139] In the formula, λ d is the speed reduction coefficient, which is related to the maximum temperature change rate η max With the minimum value η min The specific relationship is:

[0140]

[0141] 3.3 High temperature cross speed reduction strategy

[0142] In the high temperature range, the initial temperature range of each temperature ring is the fourth temperature range, but the temperature of the temperature ring varies greatly across regions. At this time, the cooling system needs to slow down in time to reduce the system energy consumption demand, so as to ensure that the system continues to operate at a higher efficiency. Assume that the temperature cross-domain change time is δ f , calculate δ f The maximum temperature difference corresponding to each temperature ring after a certain period of time is calculated as follows:

[0143] T D =max[(T Umax -T U ),(T Bmax -T B ),(T Mmax -T M )]

[0144] In δ f During this time, the fan speed is adjusted to speed v n , according to the maximum temperature difference T D Respond promptly to temperature changes. The specific corresponding relationship is:

[0145]

[0146] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for cross-domain thermal management of system temperature of a power unit, characterized in that: The system temperature cross-domain thermal management method of the power unit includes: Step 1: System temperature loop parameter setting; Step 2: Design of temperature reduction strategy based on temperature span level; Step 3: Design of energy saving strategy based on temperature span level.

2. The system temperature cross-domain thermal management method of a power unit according to claim 1, characterized in that: In step 1, during the process of setting the system temperature loop parameters, specific temperature loop parameter settings are carried out as follows: In the integrated chassis system, the thermal management system consists of a high-temperature loop, a low-temperature loop and a medium-temperature loop. Since the engine temperature is relatively high, the engine and its controller loop are defined as a high-temperature loop; the generator temperature is relatively low, so the generator and its controller loop are defined as a low-temperature loop; the on-board battery pack loop in the chassis system is an independent cooling loop, defined as a medium-temperature loop, which includes: The initial temperature of the high temperature ring is T U , its range of change corresponds to: H1=[0,t u1 ]、H2=(t u1 ,t u2 ]、H3=(t u2 ,t u3 ]、H4=(t u3 ,t u4 ]; meet the conditions: 0 <t u1 <t u2 <t u3 <t u4 ; The initial temperature of the low temperature ring is T B , its range of change corresponds to: B1=[0,t b1 ]、B2=(t b1 ,t b2 ]、B3=(t b2 ,t b3 ]、B4=(t b3 ,t b4 ]; meet the conditions: 0 <t b1 <t b2 <t b3 <t b4 ; The initial temperature of the medium temperature ring is T M , its range of variation corresponds to: M1=[0,t m1 ]、M2=(t m1 ,t m2 ]、M3=(t m2 ,t m3 ]、M4=(t m3 ,t m4 ]; meet the conditions: 0 <t m1 <t m2 <t m3 <t m4 ; According to the temperature range of the temperature ring, the speed of the cooling fan in the thermal management system changes synchronously, and it changes dynamically and adaptively between 0 and 5500 rpm at different rates to ensure the normal operation of each subsystem and the stable performance maintenance; Set the above H1, B1, M1 as the first temperature range, H2, B2, M2 as the second temperature range, H3, B3, M3 as the third temperature range, H4, B4, M4 as the fourth temperature range; in the actual cooling fan speed control process, assume that the actual speed of the current fan is n a , adjust the fan speed v according to temperature changes n By adjusting, the target speed n can be obtained g , and its tolerance range is [n g -5,n g +5].

3. The system temperature cross-domain thermal management method of the power unit according to claim 2, characterized in that: In step 1, when setting specific temperature loop parameters, the system temperature cross-domain determination process is as follows: Due to differences in working and operating conditions, the temperature changes of different subsystems of the chassis are relatively random and may span multiple temperature ranges in a short period of time. In order to respond to temperature changes, the thermal management system needs to respond to the fan speed according to the actual temperature changes. At this time, it is necessary to quantify the temperature changes. The temperature variation ranges of each temperature ring of high, medium and low and the corresponding temperature cross-domain variation levels are shown in Table 1 below; Table 1 System temperature rise cross-domain determination According to the cross-domain level of system temperature, the speed increase rate of the cooling fan is further adjusted and controlled to achieve overall control of the system temperature.

4. The system temperature cross-domain thermal management method of a power unit according to claim 3, characterized in that: In step 2, during the temperature reduction strategy design process based on the temperature span level, a low temperature span temperature reduction speed regulation strategy design process is carried out: According to the temperature crossing level, the fan speed is adjusted during the system temperature rising process. n Real-time regulation is performed to meet the dynamic cooling requirements of the actual chassis system; In the low temperature range, if the initial temperature range of each temperature ring is the highest of the first temperature range, then in the process of temperature ring temperature changing across the region, it is assumed that the change time is δ f , which corresponds to the fan speed adjustment speed v n Need to be in δ f According to the target speed n g Respond promptly to temperature changes. The specific corresponding relationship is: In the low temperature range, if the initial temperature range of each temperature ring is the highest in the second temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , which corresponds to the fan speed adjustment speed v in claim 2 n Need to be in δ f According to the target speed value n g Respond promptly to temperature changes. The specific corresponding relationship is: In the low temperature range, if the initial temperature range of each temperature ring is up to the third temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f Target speed n within time g Respond promptly to temperature changes. The specific corresponding relationship is:

5. The system temperature cross-domain thermal management method of the power unit according to claim 4, characterized in that: In step 2, during the temperature reduction strategy design process based on the temperature span level, a medium temperature span temperature reduction speed regulation strategy design process is carried out: In the middle temperature range, no matter the initial temperature is in the first temperature range or the second temperature range, the temperature ring temperature changes across regions at this time, and the cooling fan needs to respond in time; in the temperature cross-domain change time δ f Calculate the initial high temperature ring temperature T U , low temperature ring temperature T B and the medium temperature ring temperature T M The corresponding temperature change rate η U , η B , η M , then we have the following formula: Where, T Umax , T Bmax and T Mmax are the maximum temperatures of each temperature ring after the temperature changes across the domain; Based on this, the maximum value η of the temperature change rate is extracted max and the minimum value η min They correspond to: Fan speed adjustment speed v n The maximum temperature change rate η max , minimum value η min , and the cross-domain change time δ f and actual speed n a , target speed n g The dynamic changes of the , the specific corresponding relationship is: In the formula, λ u is the temperature variation coefficient, which is related to the maximum temperature change rate η max With the minimum value η min The specific relationship is:

6. The system temperature cross-domain thermal management method of the power unit according to claim 5, characterized in that: In step 2, during the temperature reduction strategy design process based on the temperature span level, a high temperature span temperature reduction speed regulation strategy design process is carried out: In the high temperature range, the initial temperature range of each temperature ring is the first temperature range, but the temperature of the temperature ring varies greatly across regions. At this time, the cooling system needs to speed up in time to respond to such a drastic temperature change. Assuming that the temperature cross-domain change time is δ f , calculate δ f The maximum temperature difference corresponding to each temperature ring after time is: T D =max[(T Umax -T U ),(T Bmax -T B ),(T Mmax -T M )] In δ f During this time, the fan speed is adjusted to speed v n According to the maximum temperature difference T D And the actual speed n a , target speed n g Respond promptly to temperature changes. The specific corresponding relationship is:

7. The system temperature cross-domain thermal management method of a power unit according to claim 3, characterized in that: In step 3, during the consumption reduction strategy design process based on the temperature span level, a low temperature span speed reduction strategy design process is carried out: According to the temperature crossing level, the fan speed response speed v of the system cooling fan when the temperature drops during the temperature drop process n Conduct real-time control to reduce the actual energy consumption demand of the chassis system; In the low temperature range, if the initial temperature range of each temperature ring is up to the fourth temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f Within the time, according to the target speed n g The dynamic changes of the temperature should be responded to in time. The specific corresponding relationship is: In the low temperature range, if the initial temperature range of each temperature ring is up to the third temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the fan speed adjustment speed v n Need to be in δ f Within the time, according to the weighted target speed n g The dynamic changes of the temperature should be responded to in time. The specific corresponding relationship is: In the low temperature range, if the initial temperature range of each temperature ring is the highest in the second temperature range, then in the process of the temperature ring temperature changing across the region, it is assumed that the change time is δ f , the corresponding fan speed adjustment speed v n Need to be in δ f Respond promptly to temperature changes within a certain period of time. The specific corresponding relationship is:

8. The system temperature cross-domain thermal management method of a power unit according to claim 7, characterized in that: In step 3, during the consumption reduction strategy design process based on the temperature span level, a medium temperature span speed reduction strategy design process is carried out: In the middle temperature range, no matter the initial temperature is in the third or fourth temperature range, the cross-region temperature change of the temperature ring at this time shows obvious fluctuations, and the cooling fan needs to respond in time; in the temperature cross-domain change time δ f Calculate the initial high temperature ring temperature T U , low temperature ring temperature T B and the medium temperature ring temperature T M The corresponding temperature change rate η U , η B , η M , then we have the following formula: Where, T Umin , T Bmin and T Mmin are the minimum temperatures of each temperature ring after the temperature changes across the domain; Based on this, the maximum value η of the temperature change rate is extracted max and the minimum value η min Corresponding to respectively, we have: Corresponding fan speed adjustment speed v n The maximum temperature change rate η max , minimum value η min , and the cross-domain change time δ f and actual speed n a , target speed n g The dynamic changes of the , the specific corresponding relationship is: In the formula, λ d is the speed reduction coefficient, which is related to the maximum temperature change rate η max With the minimum value η min The specific relationship is:

9. The system temperature cross-domain thermal management method of a power unit according to claim 8, characterized in that: In step 3, during the design of the energy saving strategy based on the temperature span level, a high temperature span speed reduction strategy design process is carried out: In the high temperature range, the initial temperature range of each temperature ring is the fourth temperature range, but the temperature of the temperature ring varies greatly across regions. At this time, the cooling system needs to slow down in time to reduce the energy consumption demand of the system, so as to ensure that the system continues to operate at a higher efficiency. Assuming that the temperature cross-domain change time is δ f , calculate δ f The maximum temperature difference corresponding to each temperature ring after a certain period of time is calculated as follows: T D =max[(T Umax -T U ),(T Bmax -T B ),(T Mmax -T M )] In δ f During this time, the fan speed is adjusted to speed v n要 According to the maximum temperature difference T D Respond promptly to temperature changes. The specific corresponding relationship is:

10. The system temperature cross-domain thermal management method of a power unit according to claim 9, characterized in that: The method makes a comprehensive reference based on the initial positioning of the temperature range of different circuits, the temperature crossing level, the temperature change value and the change rate, and determines the specific target speed range and adjustment time based on the state judgment, thereby completing the rapid adjustment of the system temperature under different temperature domain crossing conditions, and realizing the design of the control process for rapid heat dissipation and energy consumption response rapid adjustment of multiple temperature fields of the whole vehicle.

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