A Temperature-Based Control Method for Electric Drive Systems

Abstract

This invention belongs to the technical field of vehicle multi-function electric drive systems, specifically relating to a temperature-based control method for an electric drive system. The electric drive system comprises several electronic and / or mechanical components acting as working nodes, wherein any working node can transfer heat with at least one other adjacent working node. The method includes: calculating the temperature data of each working node at the next moment based on the thermal balance equation of the working nodes and the current temperature data of each working node; wherein the current temperature data of each working node is obtained based on the initial temperature of the working node and its thermal balance equation; and based on the real-time temperature data of one or more working nodes, implementing corresponding temperature protection strategies to control the operation of the motor in the electric drive system. This invention can accurately detect the temperature of different electronic and mechanical components in the electric drive system, reducing actual costs and simplifying the manufacturing process.

Description

Technical Field

[0001] This invention belongs to the technical field of vehicle all-in-one electric drive system, specifically relating to an electric drive system control method based on temperature calculation. Background Technology

[0002] Taking the drive motor of new energy vehicles as an example, the higher the motor's speed, torque density, and power density, the more heat it generates. Therefore, the heat dissipation and cooling structure of the electric bridge is essential for the reliable, stable, and efficient operation of the motor. The cooling of the electric bridge can be divided into air cooling, water cooling, and oil cooling. Oil cooling, with its natural electrical insulation and high degree of freedom in structural design, is becoming the preferred cooling solution for high-performance electric bridges.

[0003] Compared to water-cooled EDM bridges, oil-cooled EDM bridges directly cool the heat-generating components, resulting in higher cooling efficiency and widespread application in the new energy vehicle sector. However, the temperature of an oil-cooled EDM bridge fluctuates constantly during operation, and excessively high temperatures can affect its safety and lifespan. Therefore, the primary method is to install temperature sensors on the bridge to monitor these changes. However, due to the limitations of the cooling method, this approach suffers from significant detection errors, impacting the motor's performance output. Furthermore, placing multiple temperature sensors on the bridge greatly increases product cost and manufacturing complexity. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a temperature detection method that can avoid the need for a large number of temperature sensors, and accurately detect the temperature changes of different electronic and mechanical components on the oil-cooled bridge with lower cost and simpler process complexity, so as to facilitate the control of motor output performance.

[0005] To achieve the above and other related objectives, this invention provides a temperature-based control method for an electric drive system. The electric drive system comprises several electronic and / or mechanical components serving as working nodes, wherein any working node can transfer heat with at least one other adjacent working node. The method includes: calculating the temperature data of each working node at the next moment based on the thermal balance equation of the working nodes and the temperature data of each working node at the current moment; wherein the temperature data of each working node at the current moment is obtained based on the initial temperature of the working node and its thermal balance equation; and controlling the operation of the motor in the electric drive system based on the real-time temperature data of one or more working nodes, employing corresponding temperature protection strategies.

[0006] According to a specific embodiment of the present invention, the electric drive system includes at least: a motor, a motor controller, a reducer, and a cooling module; wherein the motor controller is provided with a temperature sensor for detecting temperature changes and a current sensor for detecting current changes; the electronic and / or mechanical components serving as working nodes include: motor windings, motor magnets, motor coolant, motor controller, motor controller coolant, reducer, heat exchanger, and radiator.

[0007] According to a specific embodiment of the present invention, the step of obtaining the initial temperature of the working node includes: after the electric drive system is powered on, calculating the initial temperature of the motor winding based on the resistance value of the motor winding; obtaining the initial temperature of the motor controller through the temperature sensor of the motor controller; and selecting the maximum value between the initial temperature of the motor winding and the initial temperature of the motor controller as the initial temperature of each node.

[0008] According to a specific embodiment of the present invention, the step of obtaining the resistance value of the motor winding includes: sending multiple short-time DC pulse voltages through the motor controller, and collecting the corresponding line current of the motor through the current sensor of the motor controller; calculating multiple resistance values ​​of the motor winding based on the short-time DC pulse voltages and the line current, and taking the average of the remaining multiple resistance values ​​as the final resistance value of the motor winding after removing the resistance values ​​calculated by the first and last short-time DC pulse voltages.

[0009] According to a specific embodiment of the present invention, before obtaining the heat balance equation, the method further includes: fitting the thermal power values ​​of each working node under different operating conditions using preset test data, and constructing a corresponding database based on them; obtaining the equivalent thermal resistance between adjacent working nodes and the equivalent heat capacity of each working node by fitting the preset test data, and constructing a corresponding database based on them.

[0010] According to a specific embodiment of the present invention, the heat balance equation is obtained as follows: For each operating node, the product of the temperature rise rate between the current time and the previous time and the equivalent heat capacity corresponding to the operating node is calculated as a first temperature change; the quotient of the temperature difference between the operating node and its adjacent operating nodes with respect to the current time and the equivalent thermal resistance between the operating node and its adjacent operating nodes is calculated as a second temperature change; an equation concerning energy conservation is established based on the first temperature change, the second temperature change, and the heat power value corresponding to the current operating condition of the operating node to form the heat balance equation.

[0011] According to a specific embodiment of the present invention, the formula of the heat balance equation is as follows:

[0012]

[0013] in, Let represent the temperature of the nth working node at time i, and Δt represent the time interval between time i and time i+1. R represents the temperature of the j-th working node adjacent to the n-th working node at time i. j,n P represents the equivalent thermal resistance between the nth working node and its adjacent jth working node. n C represents the thermal power value of the nth operating node. n This represents the equivalent heat capacity of the nth working node.

[0014] According to a specific embodiment of the present invention, the step of obtaining the temperature data of the working node at the current moment includes: taking the time corresponding to the initial temperature of the working node as the initial moment, and calculating the temperature data of the working node at the next moment after the initial moment based on the heat balance equation of the working node and the initial temperature of the adjacent working nodes; and calculating the temperature data of the working node at the current moment in chronological order based on the changes in the working condition of the working node.

[0015] According to a specific embodiment of the present invention, the step of controlling the operation of the motor by adopting a corresponding temperature protection strategy based on the real-time temperature data of one or more working nodes includes: adjusting the output performance of the motor in the electric drive system according to the temperature data of the working node at the current moment.

[0016] According to a specific embodiment of the present invention, it further includes: diagnosing whether the temperature data calculated by each working node converges reliably.

[0017] According to a specific embodiment of the present invention, the step of diagnosing whether the temperature data of the working node is converged and reliable includes: identifying whether the electric drive system is currently operating in a high torque load condition range through the motor controller; if so, calculating the temperature rise rate of a specific working node based on the temperature data of each working node within the high torque load condition range, and comparing it with the standard value of the temperature rise rate under the same condition in the preset database, so as to identify whether the temperature data currently calculated by the working node is converged and reliable.

[0018] This invention provides a method for detecting the temperature of an oil-cooled electric bridge, which can reduce the cost of arranging temperature sensors and thus reduce the process complexity of installing temperature sensors on the oil-cooled electric bridge. It can obtain the operating temperature of key electronic or mechanical components such as motor windings and magnets in real time during vehicle operation, so as to control the performance output of the motor accordingly, avoid temperature runaway, and thus improve the reliability of the oil-cooled electric bridge. Attached Figure Description

[0019] Figure 1This is a flowchart illustrating a specific embodiment of a temperature-based electric drive system control method provided by the present invention.

[0020] Figure 2 This is a flowchart illustrating another specific embodiment of the temperature-based electric drive system control method provided by the present invention.

[0021] Figure 3 This is a schematic diagram of a specific embodiment of the equivalent node network of the electric drive system provided by the present invention.

[0022] Figure 4 A waveform diagram of a specific embodiment of the short-time pulse voltage sent by the motor controller provided by the present invention;

[0023] Figure 5 This is a schematic diagram of a specific embodiment of the motor's output performance adjustment as a function of temperature provided by the present invention.

[0024] Figure 6 A schematic diagram of a specific embodiment of an electric drive system control system based on temperature calculation provided by the present invention;

[0025] Figure 7 This is a structural block diagram of a specific embodiment of an electronic device provided by the present invention. Detailed Implementation

[0026] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand 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 illustrating the present invention and not for limiting the scope of protection of the present invention.

[0027] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0028] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0029] First, it should be noted that, in order to enable those skilled in the art to better understand the solution of this application, the technical background of this application will be explained accordingly.

[0030] It is understandable that an oil-cooled bridge includes not only a motor, but also corresponding water-cooling and oil-cooling circuits, as well as other electronic and mechanical components, such as the heat exchanger between the water-cooling and oil-cooling circuits, the reducer that mechanically cooperates with the motor, and the corresponding motor controller. To fully utilize the performance of the oil-cooled bridge, it is necessary to monitor the temperature changes of different electronic and mechanical components during the operation of the oil-cooled motor, and adjust the motor's performance accordingly to ensure it operates at its optimal state. In this embodiment, the electric drive system refers to the oil-cooled bridge. However, the electric drive system control method of this application is not only applicable to oil-cooled bridges, but can also be adapted to bridges with other cooling methods such as water-cooled bridges; no further limitations are imposed.

[0031] Furthermore, according to Kirchhoff's laws, in a closed system, energy can neither be created nor destroyed, but only transformed from one form to another, and energy can be transferred within the system. Therefore, according to Kirchhoff's laws, energy transfer within a system can be expressed in the form of heat. Further, according to Kirchhoff's laws, when a thermodynamic system is in thermal equilibrium, the net inflow of heat is zero. In other words, the heat absorbed by one object from another is equal to the heat it releases. This means that the transfer of heat within and between systems is balanced.

[0032] Based on the above, this embodiment proposes a temperature-based control method for an electric drive system. Compared with arranging multiple temperature sensors on an oil-cooled bridge to detect temperature, this method can accurately calculate the temperature changes of different electronic and mechanical components, so as to regulate the performance release of the motor. It also reduces unnecessary costs and lowers the complexity of the process.

[0033] Example 1

[0034] Please see Figure 1 As shown in Figure 2, a control method for an electric drive system based on temperature calculation includes:

[0035] Step S100: Calculate the temperature data of each working node at the next moment based on the heat balance equation of the working node and the temperature data of each working node at the current moment; wherein, the temperature data of each working node at the current moment is obtained based on the initial temperature of the working node and its heat balance equation.

[0036] As described above, an oil-cooled bridge comprises several electronic and / or mechanical components, such as a motor, motor controller, reducer, and cooling module. Specific components that can be considered as working nodes include: motor windings, motor magnets, motor coolant, motor controller, motor controller coolant, reducer, heat exchanger, and radiator. It is understood that these electronic and / or mechanical components are connected in at least one way that can transfer heat, such as through electrical connections or physical means. Therefore, the network formed by multiple different electronic and / or mechanical components that can be considered as working nodes is equivalent to the entire oil-cooled bridge.

[0037] In one specific embodiment, reference may be made to Figure 3 The diagram shows the equivalent node network. Node 1 represents the temperature of the motor controller coolant, node 2 represents the junction temperature of the field-effect transistor (MOSFET or IGBT) in the motor controller, node 3 represents the temperature of the heat exchanger, node 4 represents the temperature of the radiator, node 5 represents the temperature of the motor coolant (e.g., cooling oil), node 6 represents the temperature of the motor windings, node 7 represents the temperature of the motor magnets, and node 8 represents the temperature of the gearbox.

[0038] It should be noted that, Figure 3 The schematic diagram of the equivalent node network of the oil-cooled electric bridge shown is for reference only. In practical applications, due to the differences between different oil-cooled motors, the electronic and mechanical components are different accordingly, and working nodes can be added / deleted accordingly. Modifications and refinements made by those skilled in the art to the embodiments of the present invention without departing from the spirit of the present invention still fall within the scope of the invention application patent of the present invention.

[0039] Furthermore, the following can be used as a reference for obtaining the heat balance equation between a working node and its adjacent working nodes:

[0040] First, the thermal power values ​​of each working node of the oil-cooled bridge under different operating conditions can be fitted using pre-set test data. Specifically, since the operating parameters of the oil-cooled bridge vary under different operating conditions—for example, the values ​​of speed, torque, and bus voltage will adjust before and after changes in operating conditions—the operating parameters of the oil-cooled bridge under different operating conditions can be pre-determined. Based on the pre-set operating parameters for one operating condition, the heat generation power (i.e., thermal power value) of each working node under that condition can be calculated. This allows the creation of a database of thermal power values ​​for each working node under different operating conditions, enabling the acquisition of the thermal power value of each working node based on the current operating condition of the oil-cooled bridge. For example, the thermal power value of a specific working node under a certain operating condition can be extracted from the database, and the temperature data of that working node at that moment can be calculated accordingly.

[0041] It should also be noted that since any operating condition of an oil-cooled motor may last for a certain period of time, and the components in the oil-cooled bridge still cause some losses within the cycle of an operating condition, the thermal power value of a working node will continuously change over time. Therefore, it is necessary to fit the thermal power values ​​of each working node under the same operating condition over time to build a complete database.

[0042] Secondly, based on the heat power values ​​obtained from the above fitting, the equivalent thermal resistance between two adjacent working nodes and the equivalent heat capacity of each working node can also be fitted, and a corresponding database can be constructed so that the corresponding parameters can be extracted from the database when calculating the temperature data of a certain working node in the future. This will not be described in detail here.

[0043] Therefore, given the thermal power value, equivalent heat capacity, and equivalent thermal resistance between the operating node and its adjacent nodes, the thermal balance equation between the operating node and its adjacent nodes can be constructed accordingly, as shown in the following formula:

[0044]

[0045] in, Let represent the temperature of the nth working node at time i, and Δt represent the time interval between time i and time i+1. R represents the temperature of the j-th working node adjacent to the n-th working node at time i. j,n P represents the equivalent thermal resistance between the nth working node and its adjacent jth working node. n C represents the thermal power value of the nth operating node. n This represents the equivalent heat capacity of the nth working node. It should be noted that the sequential numbering of the working nodes can be customized; it serves only as an identifier for the working node and will not affect the calculated temperature data of other working nodes. Therefore, no further restrictions are imposed on this.

[0046] As can be seen from the formula based on the heat balance equation, since heat is transferred between different operating nodes, the left side of the formula corresponds to the quotient of the temperature difference between the operating node for which temperature data is to be calculated and its adjacent operating node at the current moment, and the equivalent thermal resistance between these two operating nodes, i.e., the second temperature change. The heat transfer between the operating node and its adjacent operating nodes, as well as the thermal power value of the operating node for which temperature data is to be calculated under its current operating condition, are represented by summing all the second temperature changes. The right side of the formula corresponds to the product of the temperature rise rate of the operating node for which temperature data is to be calculated and its corresponding equivalent heat capacity between the current moment and the previous moment, representing the temperature change of the operating node before and after that time, i.e., the first temperature change. Furthermore, based on the conservation of heat, an energy conservation equation is established using the first temperature change, the second temperature change, and the thermal power value of the operating node under its current operating condition, ultimately forming the heat balance equation as shown above.

[0047] Furthermore, based on the aforementioned heat balance equation, to calculate the current temperature data of a specific working node, its temperature data from the previous moment is also required. This can be achieved by calculating the temperature data at any given moment sequentially based on the initial temperatures of each working node. The method for obtaining the initial temperature of a working node is as follows:

[0048] When the motor is not yet running, i.e., at zero speed, such as Figure 4 As shown, the motor controller continuously sends multiple (e.g., ≥3 times) short-duration 12V DC pulses, each lasting approximately 2ms. The current flowing through the motor windings is collected by the motor controller's built-in current sensor. The resistance of the motor windings is then calculated based on the voltage and current values, and the average of the three pulses is taken as the final resistance value. It should be noted that if multiple short-duration DC pulses are used, the resistance values ​​calculated from the first and last pulses can be discarded, and the average of the remaining resistance values ​​can be used as the final resistance value.

[0049] Finally, the initial temperature of this operating node of the motor winding can be calculated based on the resistance value of the motor winding and the actual current flowing through it. This can be understood as... Figure 4 The short-time DC pulse voltage shown is only a preferred embodiment for reference and is not intended to limit the scope of protection of this application.

[0050] Meanwhile, the initial temperature of the motor controller node can be collected by the temperature sensor built into the motor controller, and the maximum value between the initial temperature of the motor controller node and the initial temperature of the motor winding node can be selected as the equivalent initial temperature of each node and assigned accordingly.

[0051] In summary, after obtaining the initial temperature of the working node, the temperature data at any given time can be calculated according to the heat balance equation.

[0052] In one specific embodiment, with Figure 3 Taking the equivalent node network of the oil-cooled motor shown as an example, the initial time corresponding to the initial temperature is set to i = 0.

[0053] At this time, according to Figure 2 It can be seen that the nodes adjacent to node 1 include node 2, node 3, and node 4. Therefore, the heat balance equation for node 1 is as follows:

[0054]

[0055] Furthermore, given the initial temperatures of nodes 2, 3, and 4, the temperature data of node 1 at the next time step (i=1) can be calculated accordingly.

[0056] Similarly, the heat balance equation for node 2 is as follows:

[0057]

[0058] The temperature data T2 of node 2 when i=1 can be calculated accordingly. 1 .

[0059] Similarly, the temperature data of each working node i=1 can be calculated based on the initial temperature of the working node and the corresponding heat balance equation.

[0060] Similarly, given the temperature data of each working node at time i=1, the temperature data of each working node at time i=2 can be calculated accordingly. Thus, the temperature data of each working node at different times can be calculated sequentially according to the time order until the temperature data at the current time is obtained.

[0061] It should be noted that after calculating the temperature data of a certain working node at time i=1, it can be based on... and Recalculate the thermal power value P of the working node iteratively. n .

[0062] Furthermore, to verify the reliability of the calculated initial temperature, a working node equipped with a temperature sensor, such as the motor controller, is selected. After calculating the initial temperature, it is verified against the actual temperature sampling value. If the calculated initial temperature is greater than the actual temperature sampling value, the verification is considered successful, and the calculated initial temperature is used to calculate the temperature data for the next moment. If the calculated initial temperature is less than the actual temperature sampling value, the verification is considered unsuccessful, possibly indicating an abnormal initial temperature of the working node. The actual temperature sampling value is then assigned to the initial temperature of each working node, and this temperature data is used to calculate the temperature data for the next moment. In a specific embodiment, the junction temperature of the MOSFET or IGBT in the motor controller can be used.

[0063] Step S200: Based on the temperature data of one or more working nodes at the next moment, adopt the corresponding over-temperature protection strategy to control the motor operation.

[0064] After calculating the temperature data of all working nodes, the motor's output performance can be adjusted based on the temperature data of one or more working nodes to ensure the oil-cooled bridge operates at its optimal state. Specifically, the corresponding temperature change is calculated based on the temperature data of the working node at the current moment and the temperature data at the next moment, and the motor's output performance is adjusted accordingly.

[0065] Preferred, with Figure 3 Taking the equivalent node network of the oil-cooled motor shown as an example, the temperature change at node 6 can be used as the derating or derating standard for the motor. See details... Figure 5 As shown, for different temperature change ranges, the output performance of the motor can be increased or decreased according to a preset functional relationship, such as a linear proportional relationship or a non-linear proportional relationship, for example, controlling the maximum output power of the motor, without much restriction.

[0066] It should be noted that in practical applications, there are no strict restrictions on which one or more working nodes' temperature changes are used to adjust the motor's output performance. The above embodiments are for reference only and are not intended to limit the scope of protection of this application. Modifications and refinements made by those skilled in the art to the embodiments of this invention without departing from the spirit of this invention still fall within the scope of the invention application patent.

[0067] Furthermore, this embodiment also includes diagnosing the calculated temperature data to determine whether the data converges reliably. Specifically, in practical applications, temperature data from any two adjacent moments of a certain operating node can be selected, and the convergence reliability of the temperature data can be diagnosed based on the temperature change corresponding to the temperature data at the two adjacent moments and the pre-stored standard value. In a specific embodiment, node 6 can be selected, i.e., diagnosing the currently calculated temperature data of the motor winding. First, the motor controller determines whether the oil-cooled bridge is currently operating in the high-torque load range. For example, it identifies whether the high torque is greater than or equal to the product of the motor peak torque and the fac coefficient (e.g., fac is 0.6). If this condition is met, it can be considered that the oil-cooled bridge is currently operating in the high-torque load range. Then, the corresponding temperature rise rate can be calculated based on the temperature data of the operating node of the motor winding during the middle 2 / 3 of the time range within the high-torque load range. It can be understood here that the temperature data used to calculate the temperature rise rate is calculated based on the thermal balance equation of the motor winding, so that the temperature data calculated using the thermal balance equation can be diagnosed. Finally, the calculated temperature rise rate is compared with the standard value of the temperature rise rate pre-stored in the database to diagnose whether the calculated temperature data converges and is reliable. An alarm response can be issued for abnormal temperature data, without limitation. Of course, other working nodes or multiple other working nodes can also be selected for diagnosis. Furthermore, if the temperature data error is large, the adjustment of the oil-cooled motor's output performance can be stopped, thereby improving the reliability of motor control and management.

[0068] It should be noted that the steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split into multiple steps. As long as they contain the same logical relationship, they are all within the scope of protection of this patent. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, but without changing the core design of the algorithm and process, are also within the scope of protection of this patent.

[0069] Example 2

[0070] Please see Figure 6 As shown in the figure, this application embodiment also provides an electric drive system control system based on temperature calculation, including:

[0071] Temperature calculation module 10 is used to calculate the temperature data of each working node at the next moment based on the heat balance equation of the working node and the temperature data of each working node at the current moment; wherein, the temperature data of each working node at the current moment is obtained based on the initial temperature of the working node and its heat balance equation.

[0072] The over-temperature protection module 20 is used to control the motor operation by adopting corresponding temperature protection strategies based on the real-time temperature data of one or more working nodes.

[0073] It should be noted that the temperature-calculation-based electric drive system control system provided in the above embodiments belongs to the same concept as the temperature-calculation-based electric drive system control method provided in Embodiment 1 above. The specific operation methods of each module and unit have been described in detail in the method embodiments and will not be repeated here. In practical applications, the temperature-calculation-based electric drive system control method provided in Embodiment 1 above can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. This is not a limitation here.

[0074] Example 3

[0075] Please see Figure 7 As shown, embodiments of this application also provide an electronic device, including a memory 2, a processor 1, and a program stored in the memory and executable on the processor, wherein the processor executes the steps of any of the methods described above.

[0076] The memory includes at least one type of readable storage medium, such as flash memory, portable hard drive, multimedia card, card-type memory (e.g., SD or DX memory), magnetic memory, magnetic disk, optical disk, etc. In some embodiments, the memory can be an internal storage unit of an electronic device, such as a portable hard drive. In other embodiments, the memory can be an external storage device of the electronic device, such as a plug-in portable hard drive, Smart Media Card (SMC), Secure Digital (SD) card, Flash Card, etc. Furthermore, the memory can include both internal and external storage units of the electronic device. The memory can be used not only to store application software and various types of data installed on the electronic device, but also to temporarily store data that has been output or will be output.

[0077] In some embodiments, a processor may be composed of integrated circuits, such as a single packaged integrated circuit or multiple integrated circuits packaged with the same or different functions. This includes combinations of one or more central processing units (CPUs), microprocessors, digital processing chips, graphics processors, and various control chips. The processor is the control unit of the electronic device, connecting various components of the device via various interfaces and lines. It executes programs or modules stored in the memory and calls data stored in the memory to perform various functions and process data within the electronic device.

[0078] The processor executes the operating system of the electronic device and various installed applications. The processor executes the applications to implement the steps in the above method embodiments.

[0079] For example, the program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules can be a series of program instruction segments capable of performing specific functions, which describe the execution process of the program in the vehicle terminal.

[0080] The integrated unit implemented as a software functional module described above can be stored in a computer-readable storage medium. This software functional module, stored in a storage medium, includes several instructions to cause a computer device (which may be a personal computer, computer equipment, or network device, etc.) or processor to execute some functions of the temperature-calculated electric drive system control method of the various embodiments of the present invention.

[0081] In summary, this invention provides a method for detecting the temperature of an oil-cooled electric bridge, which can reduce the cost of arranging temperature sensors and thus reduce the process complexity of installing temperature sensors on the oil-cooled electric bridge. It can acquire the operating temperature of key electronic or mechanical components such as motor windings and magnets in real time during vehicle operation, so as to control the performance output of the motor accordingly, avoid temperature runaway, and thus improve the reliability of the oil-cooled electric bridge.

[0082] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A control method for an electric drive system based on temperature calculation, characterized in that, The electric drive system comprises a plurality of electronic and / or mechanical components serving as working nodes, and the electric drive system includes at least a motor controller; wherein, any working node can transfer heat with at least one other adjacent working node; the method includes: The temperature data of each working node at the next moment is calculated based on the heat balance equation of the working node and the temperature data of each working node at the current moment; wherein, the temperature data of each working node at the current moment is obtained based on the initial temperature of the working node and its heat balance equation. Based on the real-time temperature data of one or more working nodes, a corresponding temperature protection strategy is adopted to control the operation of the motor in the electric drive system. The steps for diagnosing whether the temperature data calculated by each working node converges reliably include: The motor controller identifies whether the electric drive system is currently operating in a high-torque load range. If so, the temperature rise rate of a specific working node is calculated based on the temperature data of each working node within the high torque load operating range, and compared with the standard value of the temperature rise rate under the same operating condition in the preset database to identify whether the temperature data currently calculated for the working node is convergent and reliable.

2. The control method for an electric drive system based on temperature calculation according to claim 1, characterized in that, The electric drive system includes at least: a motor, a motor controller, a reducer, and a cooling module; wherein the motor controller is equipped with a temperature sensor for detecting temperature changes and a current sensor for detecting current changes. Electronic and / or mechanical components that serve as working nodes include: motor windings, motor magnets, motor coolant, motor controller, motor controller coolant, reducer, heat exchanger, and radiator.

3. The temperature-based electric drive system control method according to claim 2, characterized in that, The steps to obtain the initial temperature of the working node include: After the electric drive system is powered on, the initial temperature of the motor winding is calculated based on the resistance value of the motor winding. The initial temperature of the motor controller is obtained through the temperature sensor of the motor controller; The maximum value between the initial temperature of the motor windings and the initial temperature of the motor controller is selected as the initial temperature of each node.

4. The electric drive system control method based on temperature calculation according to claim 3, characterized in that, The steps for obtaining the resistance value of the motor winding include: The motor controller sends multiple short-time DC pulse voltages, and the current sensor of the motor controller collects the corresponding line current of the motor. Multiple resistance values ​​of the motor winding are calculated based on the short-time DC pulse voltage and the line current. After removing the resistance values ​​calculated from the first and last short-time DC pulse voltages, the average of the remaining multiple resistance values ​​is taken as the final resistance value of the motor winding.

5. The control method for an electric drive system based on temperature calculation according to claim 1, characterized in that, Before obtaining the heat balance equation, the process also includes: The thermal power values ​​of each working node under different operating conditions are fitted by pre-set test data, and a corresponding database is constructed based on them; The equivalent thermal resistance between adjacent working nodes and the equivalent heat capacity of each working node are obtained by fitting pre-set test data, and a corresponding database is constructed based on them.

6. The control method for an electric drive system based on temperature calculation according to claim 1, characterized in that, The heat balance equation is obtained as follows: For each work node, The product of the temperature rise rate between the current time and the previous time of the working node and the equivalent heat capacity corresponding to the working node is calculated as the first temperature change. The quotient of the temperature difference between the working node and its adjacent working nodes at the current time and the equivalent thermal resistance between the working node and its adjacent working nodes is calculated as the second temperature change. Based on the first temperature change, the second temperature change, and the thermal power value corresponding to the current operating condition of the working node, an equation regarding energy conservation is established to form the thermal balance equation.

7. The control method for an electric drive system based on temperature calculation according to claim 1, characterized in that, The steps to obtain the temperature data of the current working node include: The time corresponding to the initial temperature of the working node is taken as the initial time, and the temperature data of the working node at the next time after the initial time is calculated based on the heat balance equation of the working node and the initial temperature of the adjacent working nodes. Based on the changes in the operating conditions of the working node, the temperature data of the working node at the current moment is calculated sequentially in chronological order.

8. The control method for an electric drive system based on temperature calculation according to claim 1, characterized in that, The steps for controlling the motor operation based on real-time temperature data from one or more working nodes, and implementing corresponding temperature protection strategies, include: Based on the temperature data at the current working node, adjust the output performance of the motor in the electric drive system.

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