Motor controller cooling liquid flow estimation method, motor controller and storage medium

Abstract

The invention relates to the technical field of heat dissipation of a motor driving system, in particular to a motor controller cooling liquid flow estimation method, a motor controller and a storage medium, and the method comprises the steps: respectively obtaining cooling liquid estimation temperatures of a first reference point and a second reference point in a liquid cooling channel of the motor controller, and the sum of the power loss of the plurality of power units between the first reference point and the second reference point; the sum of the power losses serves as first power losses of the power module, and second power losses of the power module are determined according to a preset rule on the basis of the cooling liquid estimated temperatures of the first reference point and the second reference point; and the deviation between the first power loss of the power module at the current moment and the second power loss of the power module at the previous moment is used as input, and the estimated value of the cooling liquid flow at the current moment is obtained through PI algorithm adjustment. The problem that the cooling liquid flow in an existing electric drive system cannot be monitored is solved, and the advantages of being low in cost and good in working condition adaptability are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation of motor drive systems, and particularly to a method for estimating the coolant flow rate of a motor controller, a motor controller, and a storage medium. Background Art

[0002] Currently, with the continuous expansion of the new energy vehicle market, motor controllers are widely used in new energy vehicles. The reliability requirements of vehicles are becoming increasingly strict, and customer safety is of utmost importance. The complex vehicle operating conditions pose a huge challenge to its reliability. The thermal design of the motor controller system is strongly related to the vehicle cooling system, including coolant temperature and coolant flow rate. Among them, the cost of on-vehicle coolant flow measurement instruments is relatively high. Considering the cost, the current new energy vehicle cooling systems usually do not integrate coolant flow monitoring instruments, or do not feedback the flow information to the controller.

[0003] Currently, the cooling systems used for electric drive systems on vehicles generally use PWM water pumps or switch water pumps to control the coolant flow rate. Most of them do not have flow sensors for measurement and adopt open-loop control. Once coolant leakage, blockage, etc. occur, it is often difficult to detect. At this time, if power devices such as inverters and motors output high power, due to insufficient cooling capacity, it will cause the cycle life of the devices to decrease at least, and in severe cases, overheating damage will occur, resulting in the loss of vehicle power and endangering the safety of vehicles and personnel. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for estimating the coolant flow rate of a motor controller, a motor controller, and a storage medium, so as to solve the problem that the coolant flow rate in the existing electric drive system cannot be monitored, and has the advantages of low cost and good adaptability to operating conditions.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] In the first aspect, the present invention discloses a method for estimating the coolant flow rate of a motor controller, and the method includes:

[0007] Obtain the estimated coolant temperatures of the first reference point and the second reference point arranged in the liquid cooling channel of the motor controller respectively, and the sum of the power losses of a plurality of power units between the first reference point and the second reference point;

[0008] Take the sum of the power losses as the first power loss of the power module, and determine the second power loss of the power module according to a preset rule based on the estimated coolant temperatures of the first reference point and the second reference point;

[0009] Take the deviation between the first power loss and the second power loss of the power module as the input, and obtain the estimated value of the coolant flow rate at the current moment through PI algorithm adjustment.

[0010] Furthermore, the first power loss of the power module wherein, P j is the power loss of the j-th power unit, and n is the number of power units between the first reference point and the second reference point;

[0011] The second power loss P of the power module totEst = ρ × C × ΔT i × FR i-1 , wherein, ρ is the density of the coolant, C is the specific heat capacity of the coolant, and FR i-1 is the estimated value of the coolant flow rate at the previous moment; ΔT i = T2 - T1, T1 is the estimated coolant temperature at the first reference point at the current moment, and T2 is the estimated coolant temperature at the second reference point at the current moment;

[0012] The deviation between the first power loss and the second power loss of the power module is:

[0013]

[0014] Furthermore, the first reference point is set at the inlet of the liquid cooling channel, and the second reference point is set in the liquid cooling channel and between the middle power unit and the first power unit near the water outlet.

[0015] Furthermore, the method further includes: performing a clipping process on the estimated value of the coolant flow rate at the current moment.

[0016] Furthermore, the method further includes: performing a low-pass filtering process on the obtained estimated coolant temperature difference between the first reference point and the second reference point and the sum of the power losses of several power units respectively.

[0017] In a second aspect, the present invention provides a motor controller, including a memory and a processor, wherein a computer program capable of being executed in the processor is stored in the memory, and when the processor executes the computer program, the steps of the above-mentioned method for estimating the coolant flow rate of the motor controller are implemented.

[0018] In a third aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to cause a computer to execute the above-mentioned method for estimating the coolant flow rate of the motor controller.

[0019] The present invention has the following unexpected beneficial effects: By respectively obtaining the estimated coolant temperatures of the first reference point and the second reference point arranged in the liquid cooling channel of the motor controller, and the sum of the power losses of several power units between the first reference point and the second reference point, and taking the sum of the power losses as the first power loss of the power module, determining the second power loss of the power module according to a preset rule based on the estimated coolant temperatures of the first reference point and the second reference point, and then using the deviation between the first power loss and the second power loss of the power module as the input, and adjusting it through the PI algorithm to obtain the estimated value of the coolant flow rate at the current moment, the problem that the current vehicle equipped with an electric drive system cannot know the actual coolant flow rate and is prone to cooling abnormalities leading to system failures is solved. Further, by estimating the coolant temperatures of the first reference point and the second reference point and calculating the power consumption losses of the power module between the first reference point and the second reference point, physical sensors such as flow sensors do not need to be added to the liquid-cooled electric drive system, the product cost is not increased, and the problems caused by the scatter and failure of physical sensors are also avoided, and the reliability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is one of the flowcharts of the method for estimating the coolant flow rate of the motor controller provided by an embodiment of the present invention;

[0021] Figure 2 is the second flowchart of the method for estimating the coolant flow rate of the motor controller provided by an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of the power module and the liquid cooling channel provided by an embodiment of the present invention.

[0023] In the figure, 1 - liquid cooling channel, 2 - power module, 21 - first power unit, 22 - intermediate power unit, 23 - second power unit, 24 - temperature sensor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for explaining the present invention, rather than for limiting the protection scope of the present invention.

[0025] In one embodiment, the present invention provides a method for estimating the coolant flow rate of a motor controller. The method for estimating the coolant flow rate of the motor controller is applied to a liquid-cooled electric drive system. In an exemplary embodiment, refer toFigure 3 As shown, the liquid-cooled electric drive system includes a liquid-cooling channel 1 and a power module 2. Coolant flows through the liquid-cooling channel 1, mainly used to dissipate heat from the power module 2.

[0026] Generally, the power module 2 (such as including an IGBT module) generates a certain power loss during operation and converts it into heat. A temperature sensor 24 is installed on the power module 2 to monitor the operating conditions of the power module 2. The power module 2 includes three-phase power units, namely a first power unit 21, an intermediate power unit 22, and a second power unit 23. An NTC temperature sensor is provided for each phase power unit (three NTC temperature sensors 24, corresponding to the three-phase power units 21, 22, and 23 one by one) to monitor the temperature of the power unit. Coolant flows through the liquid-cooling channel 1, and the flow direction of the coolant is from the second power unit 23 to the first power unit 21, as Figure 3 shown by the arrow in the figure.

[0027] As Figure 1 shown, the method for estimating the coolant flow rate of the motor controller provided by the present invention mainly includes the following steps:

[0028] S1, respectively obtain the estimated coolant temperatures of the first reference point and the second reference point arranged in the liquid-cooling channel of the motor controller, and the sum of the power losses of several power units between the first reference point and the second reference point.

[0029] S2, use the sum of the power losses as the first power loss of the power module, and determine the second power loss of the power module according to a preset rule based on the estimated coolant temperatures of the first reference point and the second reference point.

[0030] S3, use the deviation between the first power loss of the power module and the second power loss of the power module as the input, and obtain the estimated value of the coolant flow rate at the current moment through PI algorithm adjustment.

[0031] With such a configuration, the problem that the vehicle equipped with an electric drive system currently cannot know the actual coolant flow rate and is prone to cooling anomalies leading to system failures is solved. Further, by estimating the coolant temperatures of the first reference point and the second reference point, and calculating the power consumption losses of the power module between the first reference point and the second reference point, physical sensors such as flow sensors do not need to be added to the liquid-cooled electric drive system, the product cost is not increased, and the problems caused by the scatter and failure of physical sensors are also avoided, with high reliability.

[0032] The PI algorithm adjustment can automatically adjust to obtain the estimated coolant flow rate according to the power loss and the coolant temperature difference, making the steady-state of the estimated coolant flow rate unbiased. And through PI adjustment, it is possible to avoid introducing large calculation errors when using the direct formula method in the case of a small coolant temperature difference, and achieve the suppression of high-frequency noise of the estimated coolant flow rate.

[0033] In a preferred embodiment, the first power loss of the power module where P j is the power loss of the j-th power unit, and n is the number of power units between the first reference point and the second reference point.

[0034] The second power loss P of the power module totEst = ρ×C×ΔT i ×FR i-1 , where ρ is the density of the coolant, C is the specific heat capacity of the coolant, and FR i-1 is the estimated value of the coolant flow rate at the previous moment; ΔT i = T2 - T1, T1 is the estimated coolant temperature at the first reference point at the current moment, and T2 is the estimated coolant temperature at the second reference point at the current moment.

[0035] The deviation between the first power loss and the second power loss of the power module is:

[0036]

[0037] If there is no data from the previous cycle during system power-on initialization, that is, the current cycle is the first operation cycle, in this case, the assignment of the second power loss of the power module in the previous cycle can be completed during the initialization of the cooling system. For example, when initializing, the estimated value of the coolant flow rate in the previous cycle is set to be equal to the first power loss of the power module, that is, the deviation between the first power loss and the second power loss of the power module during initialization is 0.

[0038] In a preferred embodiment, as shown in Figure 3 , the first reference point 3 is set at the inlet of the liquid cooling channel 1, and the second reference point 4 is set in the liquid cooling channel 1 and between the middle power unit 22 and the first power unit 21 near the water outlet.

[0039] In a preferred embodiment, as shown in Figure 2 , the method further includes: performing a clipping process on the estimated value of the coolant flow rate at the current moment.

[0040] In a preferred embodiment, as shown in Figure 2As shown, in order to smooth the coolant flow rate, the method further includes: performing low-pass filtering on the estimated coolant temperature difference between the first reference point and the second reference point and the sum of the power losses of several power units respectively.

[0041] In one embodiment, the present invention provides a motor controller, including a memory and a processor. A computer program executable in the processor is stored in the memory, and when the processor executes the computer program, the steps of the above-mentioned method for estimating the coolant flow rate of the motor controller are implemented.

[0042] The motor controller in this embodiment and the Figures 1 - 2 method for estimating the coolant flow rate of the motor controller in the corresponding embodiment belong to the same concept. The specific implementation process is detailed in the corresponding method embodiment, and the technical features in the method embodiment are all correspondingly applicable in this device embodiment, which will not be elaborated here.

[0043] The motor controller of the embodiment of the present invention estimates the coolant temperatures of the first reference point and the second reference point, combines the power consumption losses of the power modules between the first reference point and the second reference point, realizes real-time calculation of the estimated flow rate of the coolant in the current cycle of the heat dissipation system, and excavates the output control ability of the motor controller according to the estimated flow rate in the current cycle, improves the reliability of the motor controller, and avoids failure caused by overheating to cause dangerous accidents.

[0044] In one embodiment, the present invention provides a computer-readable storage medium storing computer-executable instructions for causing a computer to execute the above-mentioned method for estimating the coolant flow rate of the motor controller.

[0045] The computer-readable storage medium in this embodiment and the Figures 1 - 2 method for estimating the coolant flow rate of the motor controller in the corresponding embodiment belong to the same concept. The specific implementation process is detailed in the corresponding method embodiment, and the technical features in the method embodiment are all correspondingly applicable in this device embodiment, which will not be elaborated here.

[0046] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0047] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For parts not detailed or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0048] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. A professional technician can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0049] In the embodiments provided in this application, it should be understood that the disclosed methods, controllers, and devices for estimating the coolant flow rate of a motor controller can be implemented in other ways. For example, the embodiments of the motor control system described above are merely illustrative.

[0050] All or part of the processes of the methods in the above embodiments of this application can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or interface switching device, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc., that can carry the computer program code.

[0051] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made without departing from the spirit of the present invention within the knowledge of those of ordinary skill in the art. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for estimating the coolant flow rate of a motor controller, characterized in that, Including: Respectively obtaining the estimated coolant temperature of the first reference point and the second reference point arranged in the liquid cooling channel of the motor controller, and the sum of the power losses of several power units between the first reference point and the second reference point; Taking the sum of the power losses as the first power loss of the power module, and determining the second power loss of the power module according to a preset rule based on the estimated coolant temperatures of the first reference point and the second reference point; Using the deviation between the first power loss of the power module and the second power loss of the power module as the input, and obtaining the estimated value of the coolant flow rate at the current moment through PI algorithm adjustment.

2. The method for estimating the coolant flow rate of the motor controller according to claim 1, wherein: The first power loss of the power module where P j is the power loss of the j-th power unit, and n is the number of power units between the first reference point and the second reference point; The second power loss P of the power module totEst = ρ × C × ΔT i × FR i-1 , where ρ is the density of the coolant, C is the specific heat capacity of the coolant, and FR i-1 is the estimated value of the coolant flow rate at the previous moment; ΔT i = T2 - T1, where T1 is the estimated coolant temperature at the first reference point at the current moment, and T2 is the estimated coolant temperature at the second reference point at the current moment; The deviation between the first power loss of the power module and the second power loss of the power module is:

3. The coolant flow rate estimation method for a motor controller according to claim 1, wherein: The first reference point is arranged at the entrance of the liquid cooling channel, and the second reference point is arranged in the liquid cooling channel and is located between the middle power unit and the first power unit close to the water outlet.

4. The coolant flow rate estimation method for the motor controller according to claim 1, wherein The method further includes: performing a clipping process on the estimated value of the coolant flow rate at the current moment.

5. The coolant flow rate estimation method for the motor controller according to claim 1, wherein The method further includes: respectively performing low-pass filtering on the obtained estimated coolant temperature difference between the first reference point and the second reference point and the sum of the power losses of several power units.

6. A motor controller, comprising a memory and a processor, characterized in that, The memory stores a computer program that can be executed in the processor, and when the processor executes the computer program, the steps of the method for estimating the coolant flow rate of the motor controller according to any one of claims 1 to 5 are implemented.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to cause a computer to execute the method for estimating the coolant flow rate of the motor controller according to any one of claims 1 to 5.

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