Rotor temperature estimation methods, electric vehicles, and readable storage media

Abstract

This invention provides a rotor temperature estimation method, an electric vehicle, and a readable storage medium. The rotor temperature estimation method is applied to an electric vehicle that charges its battery using a Boost converter implemented with a motor and controller. The rotor temperature estimation method includes calculation based on a first model. The calculation steps of the first model include obtaining the rotor's own losses based on the Boost input voltage, Boost output voltage, and Boost current. This configuration provides a rotor temperature estimation method for the electric vehicle under boost charging conditions. Furthermore, it considers the impact of the Boost converter on the rotor thermodynamic model, resulting in a high degree of consistency with real-world conditions. This solves the problem in existing technologies of lacking a rotor temperature estimation method for boost charging conditions, which leads to the risk of rotor demagnetization and the lack of initial temperature values ​​under other operating conditions.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and in particular to a rotor temperature estimation method, an electric vehicle, and a readable storage medium. Background Technology

[0002] With the application of new-generation silicon carbide power devices in automotive motor inverters, the battery voltage level of passenger vehicles has increased from 400V (using IGBTs) to 800V. However, most common DC fast charging stations on the market are 400V, unable to directly fast charge vehicles equipped with 800V high-voltage batteries. To enable a 400V DC charging station to charge an 800V vehicle, a boost converter is needed. This boost function can be achieved using the drive motor and inverter. Because this solution utilizes the drive motor's own inductance and the inverter's power devices, it is more cost-effective than directly adding a DC-DC converter to achieve the boost function.

[0003] If the rotor temperature cannot be accurately obtained in Boost mode, there are two main risks: 1. Over-temperature protection of the rotor cannot be provided, and the rotor magnets are at risk of demagnetization; 2. If the rotor temperature cannot be obtained in Boost mode, the rotor temperature model in drive mode cannot obtain an accurate initial value when the system switches to drive mode, which will affect the rotor temperature accuracy in drive mode, thereby affecting the correction of motor flux linkage and torque accuracy.

[0004] In summary, the existing technology lacks a method for estimating rotor temperature under boost charging conditions, which leads to the risk of rotor demagnetization and the lack of initial temperature values ​​under other conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a rotor temperature estimation method, an electric vehicle, and a readable storage medium to solve the problem that the prior art lacks a rotor temperature estimation method for boost charging conditions, which leads to the risk of rotor demagnetization and the lack of initial temperature values ​​under other operating conditions.

[0006] To address the aforementioned technical problems, according to a first aspect of the present invention, a rotor temperature estimation method is provided, applicable to an electric vehicle, wherein the electric vehicle charges the battery using a Boost boost method implemented by a motor and a controller. The rotor temperature estimation method includes: calculation based on a first model; the calculation steps of the first model include: obtaining the rotor's own losses based on the Boost input voltage, the Boost output voltage, and the Boost current.

[0007] Optionally, the calculation steps of the first model further include: obtaining the rotor temperature change value based on the rotor's own losses, rotor temperature, stator temperature and coolant temperature.

[0008] Optionally, the step of obtaining the rotor temperature change value based on the rotor's own losses, rotor temperature, stator temperature, and coolant temperature includes:

[0009] Calculate (P) loss +(T Stator -T Rotor )*R th_R_S +(T Coolant -T Rotor )*R th_R_C ) / C th_rotor .

[0010] Among them, P loss R represents the rotor's own losses. th_R_S R represents the thermal conductivity between the rotor and stator. th_R_C It is the thermal conductivity between the rotor and the coolant, C th_rotor T represents the rotor heat capacity. stator T represents the stator temperature. Rotor T represents the rotor temperature. Coolant This indicates the temperature of the coolant.

[0011] Optional, R th_R_S R th_R_C and C th_rotor Determined through experimentation and / or online self-learning.

[0012] Optionally, the rotor temperature estimation method includes: when the electric vehicle is in driving condition, obtaining the rotor temperature change value based on the second model; when the electric vehicle is in boost charging condition, obtaining the rotor temperature change value based on the first model; and obtaining a calculation result based on the rotor temperature change value.

[0013] Optionally, the step of obtaining the calculation result based on the rotor temperature change value includes: integrating the rotor temperature change value to obtain an estimated value of the rotor temperature.

[0014] Optionally, the step of obtaining the calculation result based on the rotor temperature change value includes: determining whether the rotor temperature change value is less than a threshold; if so, integrating the rotor temperature change value to obtain an estimated value of the rotor temperature; and if not, assigning an invalid value to the rotor temperature.

[0015] Optionally, the calculation steps of the second model include: calculating (P) loss +(T Stator -T Rotor )*Rth_R_S +(T Coolant -T Rotor )*R th_R_C ) / C th_rotor Among them, P loss R represents the rotor's own losses. th_R_S R represents the thermal conductivity between the rotor and stator. th_R_C It is the thermal conductivity between the rotor and the coolant, C th_rotor T represents the rotor heat capacity. stator T represents the stator temperature. Rotor T represents the rotor temperature. Coolant This indicates the temperature of the coolant.

[0016] To address the aforementioned technical problems, according to a second aspect of the present invention, an electric vehicle is provided, wherein the electric vehicle charges the battery using a Boost method implemented by a motor and a controller, and the electric vehicle includes a control unit that obtains the rotor temperature based on the aforementioned rotor temperature estimation method.

[0017] To address the aforementioned technical problems, according to a third aspect of the present invention, a readable storage medium is provided, wherein a program is stored in the readable storage medium, and when the program is executed, the aforementioned rotor temperature estimation method is performed.

[0018] Compared with existing technologies, this invention provides a rotor temperature estimation method, an electric vehicle, and a readable storage medium. The rotor temperature estimation method is applied to an electric vehicle that charges its battery using a Boost converter implemented with a motor and controller. The rotor temperature estimation method includes calculation based on a first model. The calculation steps of the first model include obtaining the rotor's own losses based on the Boost input voltage, Boost output voltage, and Boost current. This configuration provides a rotor temperature estimation method for the electric vehicle under boost charging conditions. Furthermore, it considers the impact of the Boost converter on the rotor thermodynamic model, resulting in a high degree of consistency with reality. This solves the problem in existing technologies of lacking a rotor temperature estimation method for boost charging conditions, which leads to the risk of rotor demagnetization and the lack of initial temperature values ​​under other operating conditions. Attached Figure Description

[0019] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0020] Figure 1 This is a schematic flowchart of a rotor temperature estimation method according to an embodiment of the present invention;

[0021] Figure 2This is a rotor thermal node model diagram according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the workflow of the first model according to an embodiment of the present invention;

[0023] Figure 4 This is another schematic flowchart of a rotor temperature estimation method according to an embodiment of the present invention.

[0024] In the attached image:

[0025] 1-First model; 10-Rotor; 20-Stator; 30-Coolant; 11-Rotor self-loss; 12-Rotor heat capacity; 21-Thermal conduction between rotor and stator; 31-Thermal conduction between rotor and coolant. Detailed Implementation

[0026] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0027] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. “One end” and “the other end,” as well as “proximal end” and “distal end,” generally refer to two corresponding parts, including not only endpoints. The terms “installed,” “connected,” and “joined” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral part; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements or an interaction between two elements. Furthermore, as used in this invention, the phrase "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements can be direct or indirect through an intermediate element. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of the other element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] The core idea of ​​this invention is to provide a rotor temperature estimation method, an electric vehicle, and a readable storage medium to solve the problem that the prior art lacks a rotor temperature estimation method for boost charging conditions, which leads to the risk of rotor demagnetization and the lack of initial temperature values ​​under other operating conditions.

[0029] The following description refers to the accompanying drawings.

[0030] Please refer to Figures 1 to 4 ,in, Figure 1 This is a schematic flowchart of a rotor temperature estimation method according to an embodiment of the present invention; Figure 2 This is a rotor thermal node model diagram according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the workflow of the first model according to an embodiment of the present invention; Figure 4 This is another schematic flowchart of a rotor temperature estimation method according to an embodiment of the present invention.

[0031] like Figure 1As shown, this embodiment provides a rotor temperature estimation method applied to electric vehicles. The electric vehicle charges its battery using a boost converter implemented with a motor and controller. In one embodiment, the boost converter is implemented using a drive motor and an inverter. That is, the boost converter method of the electric vehicle differs from that of a DC-DC converter.

[0032] The rotor temperature estimation method includes:

[0033] S10 When the electric vehicle is in driving condition, the rotor temperature change value is obtained based on the second model.

[0034] S20 When the electric vehicle is in boost charging mode, the rotor temperature change value is obtained based on the first model.

[0035] And, S30 obtains a calculation result based on the rotor temperature change value. S30 further includes: S31 The step of obtaining a calculation result based on the rotor temperature change value includes: determining whether the rotor temperature change value is less than a threshold. S32 If yes, then the rotor temperature change value is integrated to obtain an estimated value of the rotor temperature. And, S33 If no, then the rotor temperature is assigned an invalid value.

[0036] S20 can also be summarized as: calculation based on the first model. The calculation steps of the first model include: obtaining the rotor's own losses based on the Boost input voltage, Boost output voltage, and Boost current.

[0037] When the motor and inverter are in Boost mode, the current flowing through the motor's three-phase windings contains high-frequency ripple current at the same switching frequency. This high-frequency ripple current increases rotor iron losses, leading to a rapid rise in rotor temperature in Boost mode and a risk of demagnetization of the rotor magnets. Since the rotor is a moving part, implementing a temperature sensor within it is very complex and costly. Furthermore, even if a software model exists to estimate rotor temperature in the drive mode, the different current waveforms in the three-phase windings in the two modes result in different primary factors causing rotor temperature rise, making the existing rotor temperature model unsuitable for direct application in Boost mode.

[0038] For electric vehicles that achieve voltage boosting based on a drive motor and inverter, considering the motor's physical structure—the rotor is encased in the stator, and the stator dissipates heat through coolant flowing within the motor housing—the motor can be abstracted into three main thermal nodes: stator 20, rotor 10, and coolant 30. The temperatures of stator 20 and coolant 30 are known and can be obtained using temperature sensors or temperature models. Therefore, the thermal node diagram used to estimate the rotor temperature is shown below. Figure 2As shown. It is understandable that although this specification focuses on electric vehicles that utilize a boost converter based on a drive motor and inverter, the rotor temperature estimation method described can also be applied to other types of electric vehicles that use battery-powered boost converters.

[0039] Further analysis reveals that, in boost mode, the primary factor affecting rotor losses is high-frequency ripple. Therefore, the rotor's inherent losses should be calculated using three physical quantities: the Boost input voltage, the Boost output voltage, and the Boost current. In practice, the relationships between these variables can be determined through multiple experiments, such as using a neural network model or a further physical theory model. This specification does not limit the specific calculation model used to establish the relationships between these variables.

[0040] according to Figure 2 The calculation steps of the first model further include: obtaining the rotor temperature change value based on the rotor's own losses, rotor temperature, stator temperature and coolant temperature.

[0041] In a preferred embodiment, the step of obtaining the rotor temperature change value based on the rotor's own losses, rotor temperature, stator temperature, and coolant temperature includes:

[0042] Calculate (P) loss +(T Stator -T Rotor )*R th_R_S +(T Coolant -T Rotor )*R th_R_C ) / C th_rotor .

[0043] Among them, P loss This indicates that the rotor itself suffers losses of 11, R. th_R_S R represents the thermal conductivity between the rotor and stator. th_R_C The thermal conductivity between the rotor and the coolant is 31°C. th_rotor This indicates a rotor heat capacity of 12,T. stator T represents the stator temperature. Rotor T represents the rotor temperature. Coolant This indicates the temperature of the coolant.

[0044] Among them, R th_R_S R th_R_C and C th_rotor It can be determined through experimentation and / or online self-learning.

[0045] Understandably, after calculating the above formula and obtaining the result, the result can be output directly, or the result can be output after combining some correction steps.

[0046] The workflow diagram of the first model 1 is as follows: Figure 3 As shown. The sensor or other computing model inputs the Boost input voltage, the Boost output voltage, the Boost current, the stator temperature, and the coolant temperature into the first model 1. At the same time, the rotor temperature from the previous calculation cycle is also input into the first model 1. Then, the first model 1 outputs the rotor temperature change value. The rotor temperature change value is integrated to obtain an estimated value of the rotor temperature.

[0047] As analyzed earlier, the temperature estimation model in boost mode differs from that in normal mode. Therefore, it is necessary to first determine the current operating state of the electric vehicle and then select a suitable model for calculation. Figure 4 As shown.

[0048] Furthermore, in some embodiments, it is necessary to consider the rationality of the output results of the first and second models for diagnosis. Therefore, an upper limit check is performed on the rotor temperature change value calculated each time. If the rotor temperature change value exceeds the allowable upper limit, the rotor temperature model is considered abnormal, the rotor temperature model is shut down, and the rotor temperature is assigned an invalid value. The specific format of the invalid value can be agreed upon according to actual needs. When other algorithms receive an invalid rotor temperature value, corresponding countermeasures can be set according to actual needs. For example, an alarm light can be used. Specific measures can also be set according to actual needs, which will not be described in detail here.

[0049] Figure 4 In the illustrated embodiment, step S1 is further included to determine whether the current mode is boost mode (i.e., the boost charging condition); the current operating condition of the vehicle can be confirmed based on the determination result. In other embodiments, other steps may be set to determine the current operation of the vehicle.

[0050] In one embodiment, the calculation steps of the second model include: calculating (P) loss +(T Stator -T Rotor )*R th_R_S +(T Coolant -T Rotor )*R th_R_C ) / C th_rotor Among them, P loss R represents the rotor's own losses. th_R_S R represents the thermal conductivity between the rotor and stator. th_R_C It is the thermal conductivity between the rotor and the coolant, C th_rotor T represents the rotor heat capacity. stator T represents the stator temperature. Rotor T represents the rotor temperature. CoolantThis indicates the coolant temperature. However, the specific parameters used in the first model and the second model are different, and the methods for calculating the rotor's own losses are different. This application does not limit the calculation method of the rotor's own losses in the second model.

[0051] This embodiment proposes a rotor temperature estimation method based on motor and inverter voltage boosting, which has the following beneficial effects.

[0052] 1. The rotor temperature under boosting conditions can be obtained using software algorithms, and rotor over-temperature protection under boosting conditions can be performed based on the real-time estimated rotor temperature.

[0053] 2. By cooperating with the rotor temperature model under drive, rotor temperature estimation for all working modes of the electric drive system with boost function is realized; the accuracy of the initial rotor temperature value in drive mode is guaranteed when switching from boost mode to drive mode, the accuracy of rotor temperature correction flux is improved, and thus the torque accuracy in drive mode is also guaranteed.

[0054] This embodiment also provides an electric vehicle that charges its battery using a Boost method implemented with a motor and controller. The electric vehicle includes a control unit that obtains the rotor temperature based on the aforementioned rotor temperature estimation method. The control unit may be, for example, an ECU (Electronic Control Unit). Other components of the electric vehicle can be configured according to actual conditions and common knowledge in the art, and will not be described in detail here.

[0055] This embodiment also provides a readable storage medium storing a program that, when executed, performs the rotor temperature estimation method described above. The rotor temperature estimation method described above can also be applied to other systems that implement boost voltage functionality based on motors and inverters.

[0056] The aforementioned electric vehicle and readable storage medium also have the beneficial effect of being able to estimate rotor temperature under boost charging conditions.

[0057] In summary, this embodiment provides a rotor temperature estimation method, an electric vehicle, and a readable storage medium. The rotor temperature estimation method is applied to an electric vehicle that charges its battery using a Boost converter implemented with a motor and controller. The rotor temperature estimation method includes calculation based on a first model. The calculation steps of the first model include obtaining the rotor's own losses based on the Boost input voltage, Boost output voltage, and Boost current. This configuration provides a rotor temperature estimation method for the electric vehicle under boost charging conditions. Furthermore, it considers the impact of the Boost converter on the rotor thermodynamic model, resulting in a high degree of consistency with real-world conditions. This solves the problem in the prior art of lacking a rotor temperature estimation method for boost charging conditions, which leads to the risk of rotor demagnetization and the lack of initial temperature values ​​under other operating conditions.

[0058] The above description is only a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the present invention.

Claims

1. A method for estimating rotor temperature, characterized in that, Applied to electric vehicles, where the electric vehicle charges the battery using a Boost boost method implemented by a motor and controller, the rotor temperature estimation method includes: calculation based on a first model; the calculation steps of the first model include: obtaining the rotor's own losses based on the Boost input voltage, Boost output voltage, and Boost current; The calculation steps of the first model also include: obtaining the rotor temperature change value based on the rotor's own losses, rotor temperature, stator temperature and coolant temperature.

2. The rotor temperature estimation method according to claim 1, characterized in that, The step of obtaining the rotor temperature change value based on the rotor's own losses, rotor temperature, stator temperature, and coolant temperature includes: Calculate (P) loss +(T Stator -T Rotor )*R th_R_S +(T Coolant -T Rotor )*R th_R_C ) / C th_rotor ; Among them, P loss R represents the rotor's own losses. th_R_S R represents the thermal conductivity between the rotor and stator. th_R_C It is the thermal conductivity between the rotor and the coolant, C th_rotor T represents the rotor heat capacity. stator T represents the stator temperature. Rotor T represents the rotor temperature. Coolant This indicates the temperature of the coolant.

3. The rotor temperature estimation method according to claim 2, characterized in that, R th_R_S R th_R_C and C th_rotor Determined through experimentation and / or online self-learning.

4. The rotor temperature estimation method according to any one of claims 1 to 3, characterized in that, The rotor temperature estimation method includes: When the electric vehicle is in driving condition, the rotor temperature change value is obtained based on the second model; When the electric vehicle is in boost charging mode, the rotor temperature change value is obtained based on the first model; and... The calculation results are obtained based on the rotor temperature change value.

5. The rotor temperature estimation method according to claim 4, characterized in that, The steps for obtaining the calculation result based on the rotor temperature change value include: The rotor temperature change value is integrated to obtain an estimated value of the rotor temperature.

6. The rotor temperature estimation method according to claim 4, characterized in that, The steps for obtaining the calculation result based on the rotor temperature change value include: Determine whether the rotor temperature change value is less than a threshold; If so, the rotor temperature change value is integrated to obtain an estimated value of the rotor temperature; and, If not, the rotor temperature is assigned an invalid value.

7. The rotor temperature estimation method according to claim 4, characterized in that, The calculation steps of the second model include: Calculate (P) loss +(T Stator -T Rotor )*R th_R_S +(T Coolant -T Rotor )*R th_R_C ) / C th_rotor ; Among them, P loss R represents the rotor's own losses. th_R_S R represents the thermal conductivity between the rotor and stator. th_R_C It is the thermal conductivity between the rotor and the coolant, C th_rotor T represents the rotor heat capacity. stator T represents the stator temperature. Rotor T represents the rotor temperature. Coolant This indicates the temperature of the coolant.

8. An electric vehicle, characterized in that, The electric vehicle charges the battery using a Boost method implemented by a motor and controller. The electric vehicle includes a control unit, which obtains the rotor temperature based on the rotor temperature estimation method as described in any one of claims 1 to 7.

9. A readable storage medium, characterized in that, The readable storage medium stores a program that, when executed, performs the rotor temperature estimation method as described in any one of claims 1 to 7.

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