A Diagnostic Method and System for the Cooling Capacity of a Dual-Motor Hybrid Electric Motor

Abstract

The present invention relates to the technical field of new energy motors, and particularly relates to a method and system for diagnosing the cooling capacity of a dual-motor hybrid motor; in this method, there is a cooling circuit for diagnosis, and this cooling circuit includes a radiator, an electronic water pump, a DCDC, a generator inverter, a drive motor inverter, a generator, and a drive motor connected in sequence, and the drive motor is connected to the radiator; in this solution, the main parts of the cooling circuit are divided. During the operation of the vehicle, when the temperatures of the various components are too high, the electronic water pump can be turned on. The electronic water pump rotates to use the coolant flow to dissipate heat from the components that need to be cooled and dissipate it into the air through the radiator. By diagnosing the cooling capacity of these five parts respectively, it can effectively avoid the reduction of the motor system performance caused by the motor system working in a relatively high-temperature area for a long time due to the reduction of the cooling capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy motors, and particularly relates to a method and system for diagnosing the cooling capacity of a dual-motor hybrid motor. Background Art

[0002] At present, most of the motors used in hybrid vehicles on the market are permanent magnet synchronous motors. Permanent magnet synchronous motors are sensitive to temperature. Long-term operation at high temperatures will cause the permanent magnets to demagnetize. Therefore, an effective cooling system is required to ensure that the permanent magnet synchronous motor system operates within a reasonable temperature range.

[0003] At present, most of the management systems of permanent magnet synchronous motors adopt an open-loop control method, that is, the flow rate of the cooling system and the heat dissipation of the cooling fan are calculated based on the temperature of the motor components and the ambient temperature. When the cooling capacity of the cooling system is close to the design value, this open-loop cooling control method can basically control the temperature of the motor at the set value. However, when the cooling capacity of the cooling system decreases, still using this open-loop control method will cause the stable temperature of the motor system to be too high. Under dynamic working conditions, the temperature of the motor system will significantly exceed the set temperature range. Working in such a temperature environment for a long time will inevitably lead to a decrease in the performance of the motor system and an increase in energy consumption. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a method and system for diagnosing the cooling capacity of a dual-motor hybrid motor, which can efficiently, quickly, and accurately diagnose the cooling capacity of the dual-motor hybrid motor.

[0005] To solve the above technical problems, the technical solution provided by the present invention is: the method for diagnosing the cooling capacity of a dual-motor hybrid motor includes a cooling circuit for diagnosis. The cooling circuit includes a radiator, an electronic water pump, a DCDC, a generator inverter, a drive motor inverter, a generator, and a drive motor connected in sequence. The drive motor is connected to the radiator;

[0006] The diagnostic method includes five parts: diagnosing the cooling capacity of the DCDC, diagnosing the cooling capacity of the generator inverter, diagnosing the cooling capacity of the drive motor inverter, diagnosing the cooling capacity of the generator, and diagnosing the cooling capacity of the drive motor.

[0007] In the above technical solution, the main parts of the cooling circuit are divided. During the operation of the whole vehicle, when the temperatures of various components are too high, the electric water pump can be turned on. The electric water pump rotates to use the coolant flow to dissipate heat from the components that need to be cooled, and dissipates the heat into the air through the radiator. By diagnosing the cooling capacity of these five parts respectively, it can effectively avoid the reduction of the motor system performance caused by the motor system working in a relatively high temperature area for a long time due to the reduction of the cooling capacity.

[0008] Further, the diagnosis of the cooling capacity of the DCDC includes the following steps:

[0009] (1) Judgment of the diagnostic working condition:

[0010] (1.1) After the driver powers off the whole vehicle, if the DCDC temperature at power-off is higher than the DCDC temperature at power-on by more than the first preset temperature, it is judged that the diagnostic working condition for the cooling capacity of the DCDC is satisfied, otherwise it is judged not to be satisfied;

[0011] (2) Diagnostic steps:

[0012] (2.1) After the DCDC temperature is stable, turn off the electric water pump. If the DCDC temperature is stable within the first preset time, start the diagnosis of the cooling capacity. If it is not stable, abandon this diagnosis;

[0013] (2.2) If the DCDC temperature change rate is less than the first preset threshold value, it is judged that the DCDC temperature is stable. The first preset threshold value is obtained by looking up the table DCDC_Thd according to the ambient temperature. The DCDC temperature change rate is obtained by taking the difference of the DCDC temperatures before and after the second preset time interval;

[0014] (2.3) After the DCDC temperature is stable, bypass the cooling circuits of the generator inverter, drive motor inverter, generator and drive motor, and connect the DCDC to the cooling circuit. Then set the speed of the electric water pump to the highest. After the third preset time has passed, if the temperature reduction degree of the DCDC is less than the threshold value DCDC_1Thd, it is judged that the cooling capacity of the DCDC is insufficient. The threshold value DCDC_1Thd is obtained by looking up the table.

[0015] Further, the diagnosis of the cooling capacity of the generator inverter includes the following steps:

[0016] (1) Judgment of the diagnostic working condition:

[0017] (1.1) After the driver powers off the whole vehicle, if the generator inverter temperature at power-off is higher than the generator inverter temperature at power-on by more than the second preset temperature, it is judged that the diagnostic working condition for the cooling capacity of the generator inverter is satisfied, otherwise it is not satisfied;

[0018] (2) Diagnostic steps:

[0019] (2.1) After the temperature of the generator inverter is stable, turn off the electronic water pump. If the temperature of the generator inverter is stable within the fourth preset time, start the diagnosis of the cooling capacity. If not, abandon this diagnosis.

[0020] (2.2) If the temperature change rate of the generator inverter is less than the second preset threshold value, it is judged that the temperature of the generator inverter is stable. The second preset threshold value is obtained by looking up the table GmInvtr_Thd according to the ambient temperature. The temperature change rate of the generator inverter is obtained by the temperature difference of the generator inverter before and after the fifth preset time interval.

[0021] (2.3) After the temperature of the generator inverter is stable, bypass the cooling circuits of the DCDC, generator inverter, generator and drive motor, and connect the drive motor inverter to the cooling circuit. Then set the speed of the electronic water pump to the highest. After the sixth preset time has passed, if the temperature reduction degree of the drive motor inverter is less than the first threshold value TmInvtr_1Thd, it is judged that the cooling capacity of the drive motor inverter is insufficient. The first threshold value TmInvtr_1Thd is obtained by looking up the table.

[0022] Furthermore, the diagnosis of the cooling capacity of the generator includes the following steps:

[0023] (1) Judgment of diagnostic working conditions:

[0024] (1.1) After the driver powers off the whole vehicle, if the temperature of the generator at the time of power-off is higher than the temperature of the generator at the time of power-on by more than the third preset temperature, it is judged that the diagnostic working conditions for the cooling capacity of the generator are met, otherwise not.

[0025] (2) Diagnostic steps:

[0026] (2.1) After the temperature of the generator is stable, turn off the electronic water pump. If the temperature of the generator is stable within the seventh preset time, start the diagnosis of the cooling capacity. If not, abandon this diagnosis.

[0027] (2.2) If the temperature change rate of the generator is less than the third preset threshold value, it is judged that the temperature of the generator is stable. The third preset threshold value is obtained by looking up the table Gm_Thd according to the ambient temperature. The temperature change rate of the generator is obtained by the temperature difference of the generator before and after the eighth preset time interval.

[0028] (2.3) After the temperature of the generator stabilizes, bypass the cooling circuits of the DCDC, generator inverter, drive motor inverter, and drive motor, and connect the generator to the cooling circuit. Subsequently, set the speed of the electronic water pump to the maximum. When the ninth preset time has elapsed, if the degree of temperature reduction of the generator is less than the second threshold value TmInvtr_1Thd, it is determined that the cooling capacity of the generator is insufficient. The second threshold value TmInvtr_1Thd is obtained by looking up a table.

[0029] Furthermore, the diagnosis of the cooling capacity of the drive motor includes the following steps:

[0030] (1) Judgment of the diagnostic working condition:

[0031] (1.1) After the driver powers off the whole vehicle, if the temperature of the drive motor when powering off is higher than the temperature of the drive motor when powering on by more than the fourth preset temperature, it is determined that the diagnostic working condition for the cooling capacity of the drive motor is satisfied; otherwise, it is not satisfied.

[0032] (2) Diagnostic steps:

[0033] (2.1) After the temperature of the drive motor stabilizes, turn off the electronic water pump. If the temperature of the drive motor stabilizes within the tenth preset time, start the diagnosis of the cooling capacity; otherwise, abandon this diagnosis.

[0034] (2.2) If the temperature change rate of the drive motor is less than the fourth preset threshold value, it is determined that the temperature of the drive motor is stable. The fourth preset threshold value is obtained by looking up the table Tm_Thd based on the ambient temperature. The temperature change rate of the drive motor is obtained by taking the difference in the temperature of the drive motor before and after the eleventh preset time interval.

[0035] (2.3) After the temperature of the drive motor stabilizes, bypass the cooling circuits of the DCDC, generator inverter, drive motor inverter, and generator, and connect the drive motor to the cooling circuit. Subsequently, set the speed of the electronic water pump to the maximum. When the twelfth preset time has elapsed, if the degree of temperature reduction of the drive motor is less than the threshold value Tm_1Thd, it is determined that the cooling capacity of the drive motor is insufficient. The threshold value Tm_1Thd is obtained by looking up a table.

[0036] Furthermore, the diagnosis of the cooling capacity of the drive motor inverter includes the following steps:

[0037] (1) Judgment of the diagnostic working condition:

[0038] (1.1) After the driver powers off the whole vehicle, if the temperature of the drive motor inverter when powering off is higher than the temperature of the drive motor inverter when powering on by more than the fifth preset temperature, it is determined that the diagnostic working condition for the cooling capacity of the drive motor inverter is satisfied; otherwise, it is not satisfied.

[0039] (2) Diagnostic steps:

[0040] (2.1) After the temperature of the drive motor inverter stabilizes, turn off the electric water pump. If the temperature of the drive motor inverter stabilizes within the thirteenth preset time, start the diagnosis of the cooling capacity. If it does not stabilize, abandon this diagnosis;

[0041] (2.2) If the temperature change rate of the drive motor inverter is less than the fifth preset threshold value, it is determined that the temperature of the drive motor inverter is stable. The fifth preset threshold value is obtained by looking up the table TmInvtr_Thd based on the ambient temperature. The temperature change rate of the drive motor inverter is obtained by the temperature difference of the generator inverter before and after the thirteenth preset time interval;

[0042] (2.3) After the temperature of the drive motor inverter stabilizes, bypass the cooling circuits of the DCDC, generator inverter, generator, and drive motor, and connect the drive motor inverter to the cooling circuit. Then set the speed of the electric water pump to the maximum. When the thirteenth preset time has passed, if the temperature reduction degree of the drive motor inverter is less than the third threshold value TmInvtr_1Thd, it is determined that the cooling capacity of the drive motor inverter is insufficient. The third threshold value TmInvtr_1Thd is obtained by looking up the table.

[0043] Furthermore, the DCDC, generator inverter, drive motor inverter, generator, and drive motor are respectively connected with cooling bypass three-way valves and temperature sensors, and the electric water pump is also connected with a temperature sensor at the inlet of the cooling circuit.

[0044] Furthermore, the diagnostic processes of the five parts are not in a sequential order. The cooling capacity of the cooling circuit is diagnosed once every time the vehicle runs the rated kilometers. After the diagnostic processes of the five parts are each completed once, it is considered that the diagnosis of the cooling capacity of the cooling circuit is all completed until the vehicle runs to the rated kilometers next time.

[0045] Furthermore, a cooling fan is provided on the radiator.

[0046] The dual-motor hybrid motor cooling capacity diagnosis system described above, which includes a radiator, a cooling fan, an electric water pump, DCDC, a generator inverter, a drive motor inverter, a generator, and a drive motor. The DCDC, generator inverter, drive motor inverter, generator, and drive motor are respectively connected with cooling bypass three-way valves and temperature sensors, and the electric water pump is connected with a temperature sensor at the inlet of the cooling circuit.

[0047] Compared with the prior art, the significant advantages of this solution are:

[0048] In this solution, specific operations are used to detect whether the cooling effects of various components on the cooling system meet the design expectations, avoiding the motor system from working in a relatively high-temperature area for a long time due to reduced cooling capacity, which may lead to a decrease in the performance of the motor system. This not only improves the product life but also accumulates data for the OEM to improve relevant designs. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0050] Figure 1 is a schematic diagram of the cooling circuit structure in the diagnostic method of the present invention;

[0051] Figure 2 is a flowchart of the steps for diagnosing the cooling capacity of DCDC according to the present invention;

[0052] Figure 3 is a flowchart of the steps for diagnosing the cooling capacity of the generator inverter according to the present invention;

[0053] Figure 4 is a flowchart of the steps for diagnosing the cooling capacity of the generator according to the present invention;

[0054] Figure 5 is a flowchart of the steps for diagnosing the cooling capacity of the drive motor according to the present invention;

[0055] Figure 6 is a flowchart of the steps for diagnosing the cooling capacity of the drive motor inverter according to the present invention;

[0056] In the figure: 1 - radiator, 2 - cooling fan, 3 - electronic water pump, 4 - DCDC, 5 - generator inverter, 6 - drive motor inverter, 7 - generator, 8 - drive motor, 9 - cooling circuit inlet temperature sensor, 10 - DCDC temperature sensor, 11 - generator inverter temperature sensor, 12 - drive motor inverter temperature sensor, 13 - generator temperature sensor, 14 - drive motor temperature sensor, 15 - DCDC cooling bypass three-way valve, 16 - generator inverter cooling bypass three-way valve, 17 - drive motor inverter cooling bypass three-way valve, 18 - generator cooling bypass three-way valve, 19 - drive motor cooling bypass three-way valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0057] The following are descriptions of the preferred embodiments of the present invention with reference to the drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0058] As Figure 1As shown in the figure, in the dual-motor hybrid motor cooling capacity diagnosis method of the present invention, in this method, a cooling circuit for the dual-motor hybrid motor is first designed. The circuit structure includes a radiator 1, an electric water pump 3, a DCDC (direct current to direct current voltage converter) 4, a generator inverter 5, a drive motor inverter 6, a generator 7, and a drive motor 8 connected in sequence. The drive motor 8 is also connected to the radiator 1.

[0059] In addition, a cooling fan 2 is provided on the radiator 1. The electric water pump 3 is connected to a cooling circuit inlet water temperature sensor 9. The DCDC 4 is connected to a DCDC cooling bypass three-way valve 15 and a DCDC temperature sensor 10. The generator inverter 5 is connected to a generator inverter temperature sensor 11 and a generator inverter cooling bypass three-way valve 16. The drive motor inverter 6 is connected to a drive motor inverter temperature sensor 12 and a drive motor inverter cooling bypass three-way valve 17. The generator 7 is connected to a generator temperature sensor 13 and a generator cooling bypass three-way valve 18. The drive motor 8 is connected to a drive motor cooling bypass three-way valve 19 and a drive motor temperature sensor 14.

[0060] During the operation of the whole vehicle, when the temperature sensors of each component detect that the temperature of the component is too high, the electric water pump 3 is turned on. The electric water pump 3 rotates, and the coolant flows through the components that need to be cooled. The heat of the components is carried away by the coolant and dissipated into the air through the radiator 1. The function of the cooling fan 2 is to increase the air flow of the radiator 1 to enhance the heat dissipation capacity of the radiator 1. The different rotational speeds of the electric water pump 3 result in different coolant flows, and the heat that can be carried away from each component is also different. The higher the temperature of each component, the faster the rotational speed of the electric water pump 3, and the lower the temperature, the lower the rotational speed of the electric water pump 3.

[0061] When the upper and lower interfaces of the DCDC cooling bypass three-way valve 15 are connected, the coolant passes through the DCDC 4 and takes away the heat of the DCDC 4. When the left and lower interfaces of the DCDC cooling bypass three-way valve 15 are connected, the coolant does not pass through the DCDC 4, and the heat of the DCDC 4 cannot be carried away by the coolant, and the DCDC 4 is bypassed from the cooling circuit.

[0062] When the upper and lower interfaces of the generator inverter cooling bypass three-way valve 16 are connected, the coolant passes through the generator inverter 5 and takes away the heat of the generator inverter 5. When the left and lower interfaces of the generator inverter cooling bypass three-way valve 16 are connected, the coolant does not pass through the generator inverter 5, and the generator inverter 5 is bypassed from the cooling circuit.

[0063] When the left and right interfaces of the drive motor inverter cooling bypass three-way valve 17 are connected, the coolant passes through the drive motor inverter 6 and takes away the heat of the drive motor inverter 6. When the lower and right interfaces of the drive motor inverter cooling bypass three-way valve 17 are connected, the coolant does not pass through the drive motor inverter 6, and the drive motor inverter 6 is bypassed from the cooling circuit.

[0064] When the left and right interfaces of the generator cooling bypass three-way valve 18 are connected, the coolant passes through the generator 7 and takes away the heat of the generator 7. When the lower and right interfaces of the generator cooling bypass three-way valve 18 are connected, the coolant does not pass through the generator 7, and the generator 7 is bypassed from the cooling circuit.

[0065] When the left and right interfaces of the drive motor cooling bypass three-way valve 19 are connected, the coolant passes through the drive motor 8 and takes away the heat of the drive motor 8. When the lower and right interfaces of the drive motor cooling bypass three-way valve 19 are connected, the coolant does not pass through the drive motor 8, and the drive motor 8 is bypassed from the cooling circuit.

[0066] The temperature sensors of each component are used to collect the temperatures of the components. Among them, the cooling circuit inlet temperature sensor 9 is used to collect the inlet water temperature after the cooling circuit dissipates heat through the radiator.

[0067] In this diagnostic method, when the vehicle runs every rated kilometer, which is 5000 kilometers in this embodiment, a diagnosis of the cooling capacity of the cooling circuit is performed once. Each diagnosis includes five parts: the diagnosis of the DCDC cooling capacity, the generator inverter cooling capacity, the drive motor inverter cooling capacity, the generator cooling capacity, and the drive motor cooling capacity. Only when all five components have completed a diagnosis once, it is determined that the diagnosis of the cooling capacity of the cooling circuit is completed. After that, no more cooling capacity diagnoses are performed until the vehicle mileage reaches the rated value again, that is, 5000 kilometers.

[0068] Specifically, as Figure 2 shown, the diagnosis of the DCDC cooling capacity includes the following steps:

[0069] (1) Judgment of the diagnostic working condition:

[0070] (1.1) In a certain driving cycle, after the driver powers off the vehicle, if the temperature of the DCDC when powered off is higher than the temperature when powered on by the first preset temperature, which is 15°C or more in this embodiment, it is determined that the diagnostic working condition for the DCDC cooling capacity is met; otherwise, it is determined that it is not met.

[0071] (2) Diagnostic steps:

[0072] (2.1) First, wait for the temperature of DCDC4 to stabilize. Then, turn off the electric water pump 3 so that the coolant no longer flows. Since the vehicle has been powered off, DCDC4 basically stops working, so its heat generation no longer increases. If the temperature of DCDC4 stabilizes within the first preset time, which is 2 minutes in this embodiment, then the diagnosis of the cooling capacity starts. If it does not stabilize, this diagnosis is abandoned;

[0073] (2.2) If the temperature change rate of DCDC4 is less than the first preset threshold value, it is determined that the temperature of DCDC4 is stable. This first preset threshold value is obtained by looking up the table DCDC_Thd according to the ambient temperature. As shown in the following table, the horizontal axis of the table is the ambient temperature, and the output of the table is the temperature change rate threshold value. The temperature change rate of DCDC4 is obtained by the temperature difference of DCDC4 at intervals of the second preset time, which is 20 seconds in this embodiment, that is, (temperature 20 seconds ago - current temperature) / 20. The recommended table DCDC_Thd is as follows:

[0074]

[0075] (2.3) When the temperature of DCDC4 has stabilized, by controlling the generator inverter cooling bypass three-way valve 16, the drive motor inverter cooling bypass three-way valve 17, the generator cooling bypass three-way valve 18, and the drive motor cooling bypass three-way valve 19, the cooling circuits of the generator inverter 5, the drive motor inverter 6, the generator 7, and the drive motor 8 are bypassed. Control the DCDC cooling bypass three-way valve 15 to connect DCDC4 to the cooling circuit. Then, set the speed of the electric water pump 3 to the maximum and the speed of the cooling fan 2 to the maximum, that is, the entire cooling system cools DCDC4 with the maximum cooling capacity. When the third preset time, which is 1 minute in this embodiment, has passed, if the temperature reduction degree of DCDC4 is less than the threshold DCDC_1Thd, it is determined that the cooling capacity of DCDC4 is insufficient;

[0076] Among them, the threshold DCDC_1Thd is obtained by looking up the table. The inputs of the table are respectively the initial temperature when DCDC performs the cooling capacity detection and the ambient temperature, and the output of the table is the temperature reduction degree of DCDC after 1 minute. Select a brand-new mass-produced DCDC. At each ambient temperature, when DCDC starts forced cooling with different initial temperatures at the maximum capacity, the temperature reduction degree of DCDC after 1 minute is obtained, and this temperature reduction degree is multiplied by 1.1 as the final table value.

[0077] As Figure 3 shown, the diagnosis of the cooling capacity of the generator inverter 5 includes the following steps:

[0078] (1) Judgment of the diagnosis working condition:

[0079] (1.1) During a certain driving cycle, after the driver shuts down the entire vehicle, if the temperature of the generator inverter 5 at the time of shutdown is higher than the temperature at the time of startup by a second preset temperature, which is 15 °C or more in this embodiment, it is determined that the diagnostic condition for the cooling capacity of the generator inverter 5 is met; otherwise, it is not met.

[0080] (2) Diagnostic steps:

[0081] (2.1) First, wait for the temperature of the generator inverter 5 to stabilize, and then turn off the electric water pump 3 so that the coolant no longer flows. Since the entire vehicle has been shut down, the generator inverter 5 basically stops working, so its heat generation no longer increases. If the temperature of the generator inverter 5 stabilizes within a fourth preset time, which is 2 min in this embodiment, the cooling capacity diagnosis starts; otherwise, this diagnosis is abandoned.

[0082] (2.2) If the temperature change rate of the generator inverter 5 is less than the second preset threshold value, it is determined that the temperature of the generator inverter 5 is stable. This second preset threshold value is obtained by looking up the table GmInvtr_Thd based on the ambient temperature. The horizontal axis of the table is the ambient temperature, and the table output is the temperature change rate threshold value. The temperature change rate of the generator inverter 5 is obtained by the temperature difference of the generator inverter 5 at intervals of a fifth preset time, which is 20 s in this embodiment, that is, (temperature 20 s ago - current temperature) / 20. The recommended table GmInvtr_Thd is shown in the following table:

[0083]

[0084] (2.3) When the temperature of the generator inverter 5 has stabilized, control the DCDC cooling bypass three-way valve 15, the drive motor inverter cooling bypass three-way valve 17, the generator cooling bypass three-way valve 18, and the drive motor cooling bypass three-way valve 19 to bypass the cooling circuits of the DCDC 4, the drive motor inverter 6, the generator 7, and the drive motor 8. Control the generator inverter cooling bypass three-way valve 16 to connect the generator inverter 5 to the cooling circuit. Then, set the speed of the electric water pump 3 to the maximum and the speed of the cooling fan 2 to the maximum, that is, the entire cooling system cools the generator inverter 5 with the maximum cooling capacity. When 1 min, which is the sixth preset time in this embodiment, has passed, if the temperature reduction degree of the generator inverter 5 is less than the threshold value GmInvtr_1Thd, it is determined that the cooling capacity of the generator inverter 5 is insufficient.

[0085] Among them, the threshold GmInvtr_1Thd is obtained by looking up a table. The table inputs are the initial temperature when the generator inverter 5 performs the cooling capacity detection, the other table input is the ambient temperature, and the table output is the degree of temperature reduction of the generator inverter 5 after 1 minute. Select a brand-new mass-produced generator inverter. At each ambient temperature, when the generator inverter starts forced cooling at different initial temperatures with maximum capacity, the degree of temperature reduction of the generator inverter after 1 minute is obtained, and this degree of temperature reduction is multiplied by 1.1 as the final table value.

[0086] As Figure 4 shown, the diagnosis of the cooling capacity of the generator 7 includes the following steps:

[0087] (1) Judgment of the diagnostic working condition:

[0088] (1.1) In a certain driving cycle, after the driver powers off the whole vehicle, if the temperature of the generator 7 when powering off

[0089] is higher than the temperature when powering on by a third preset temperature, which is 20°C or more in this embodiment, it is determined that the diagnostic working condition of the cooling capacity of the generator 7 is satisfied, otherwise it is not satisfied;

[0090] (2) Diagnostic steps:

[0091] (2.1) First, wait for the temperature of the generator 7 to stabilize, and then turn off the electronic water pump 3 so that the coolant no longer flows. Since the whole vehicle has been powered off and the generator 7 basically stops working, its heat generation no longer increases. If the temperature of the generator 7 stabilizes within the seventh preset time, which is 2 minutes in this embodiment, the cooling capacity diagnosis starts. If it does not stabilize, this diagnosis is abandoned;

[0092] (2.2) If the temperature change rate of the generator 7 is less than the third preset threshold value, it is determined that the temperature of the generator 6 is stable. This third preset threshold value is obtained by looking up the table GM_Thd according to the ambient temperature. The horizontal axis of the table is the ambient temperature, and the table output is the temperature change rate threshold value. Among them, the temperature change rate of the generator 7 is obtained by the temperature difference of the generator 6 before and after the eighth preset time, which is 20s interval in this embodiment, that is, (temperature 20s ago - current temperature) / 20. The recommended table GM_Thd is shown in the following table:

[0093]

[0094] (2.3) After the temperature of the generator 7 has stabilized, by controlling the DCDC cooling bypass three-way valve 15, the generator cooling bypass three-way valve 16, the drive motor inverter cooling bypass three-way valve 17, and the drive motor cooling bypass three-way valve 19, the cooling circuits of the DCDC 4, the generator inverter 5, the drive motor inverter 6, and the drive motor 8 are bypassed. Control the generator cooling bypass three-way valve 18 to connect the generator 7 to the cooling circuit. Subsequently, set the speed of the electronic water pump 3 to the maximum and the speed of the cooling fan 2 to the maximum, that is, the entire cooling system cools the generator 6 with the maximum cooling capacity. When the ninth preset time, which is 1 min in this embodiment, has passed, if the temperature reduction of the generator 7 is less than the threshold TmInvtr_1Thd, it is determined that the cooling capacity of the generator 7 is insufficient;

[0095] Among them, the threshold TmInvtr_1Thd is obtained by looking up a table. The table inputs are the initial temperature of the generator 7 during the cooling capacity detection, and the other table input is the ambient temperature. The table output is the temperature reduction of the generator 7 after 1 min. Select a brand-new mass-produced generator. At each ambient temperature, when the generator starts forced cooling with different initial temperatures at the maximum capacity, obtain the temperature reduction of the generator after 1 min, and multiply this temperature reduction by 1.1 as the final table value.

[0096] As Figure 5 shown, the diagnosis of the cooling capacity of the drive motor 8 includes the following steps:

[0097] (1) Judgment of the diagnostic working condition:

[0098] (1.1) In a certain driving cycle, after the driver powers off the whole vehicle, if the temperature of the drive motor 8 at the time of power-off is higher than the temperature at the time of power-on by the fourth preset temperature, which is 30 °C or more in this embodiment, it is determined that the diagnostic working condition for the cooling capacity of the drive motor 8 is satisfied; otherwise, it is not satisfied.

[0099] (2) Diagnostic steps:

[0100] (2.1) First, wait for the temperature of the drive motor 8 to stabilize, and then turn off the electronic water pump 3 so that the coolant no longer flows. Since the whole vehicle has been powered off and the drive motor 8 basically stops working, its heat generation no longer increases. If the temperature of the drive motor 8 stabilizes within the tenth preset time, which is 2 min in this embodiment, the cooling capacity diagnosis starts; otherwise, this diagnosis is abandoned.

[0101] (2.2) If the temperature change rate of the drive motor 8 is less than the fourth preset threshold value, it is determined that the temperature of the drive motor 8 is stable. The fourth preset threshold value is obtained by looking up the table Tm_Thd based on the ambient temperature. The horizontal axis of the table is the ambient temperature, and the table output is the temperature change rate threshold value. The temperature change rate of the drive motor 8 is obtained by the temperature difference of the drive motor 8 before and after the eleventh preset time, which is 20 s in this embodiment, that is, (temperature 20 s ago - current temperature) / 20. The recommended table Tm_Thd is shown in the following table:

[0102]

[0103] (2.3) After the temperature of the drive motor 8 has stabilized, by controlling the DCDC cooling bypass three-way valve 15, the drive motor inverter cooling bypass three-way valve 16, the drive motor inverter cooling bypass three-way valve 17, and the generator cooling bypass three-way valve 18, the cooling circuits of the DCDC 4, the generator inverter 5, the drive motor inverter 6, and the generator 7 are bypassed. By controlling the drive motor cooling bypass three-way valve 19, the drive motor 8 is connected to the cooling circuit. Subsequently, the speed of the electronic water pump 3 is set to the maximum, and the speed of the cooling fan 2 is set to the maximum, that is, the entire cooling system cools the drive motor 8 with the maximum cooling capacity. After the twelfth preset time, which is 1 min in this embodiment, if the temperature reduction degree of the drive motor 8 is less than the threshold value Tm_1Thd, it is determined that the cooling capacity of the drive motor 8 is insufficient;

[0104] Among them, the threshold value Tm_1Thd is obtained by looking up the table. The table inputs are respectively the initial temperature when the cooling capacity of the drive motor 8 is detected, and the other table input is the ambient temperature. The table output is the temperature reduction degree of the drive motor 8 after 1 min. Select a brand-new mass-produced drive motor. At each ambient temperature, when the drive motor starts forced cooling with different initial temperatures at the maximum capacity, the temperature reduction degree of the drive motor after 1 min is obtained, and this temperature reduction degree is multiplied by 1.1 as the final table value.

[0105] As Figure 6 shown, the diagnosis of the cooling capacity of the drive motor inverter 6 includes the following steps:

[0106] (1) Judgment of the diagnostic working condition:

[0107] (1.1) In a certain driving cycle, after the driver powers off the whole vehicle, if the temperature of the drive motor inverter 6 when powering off is higher than the temperature when powering on by the fifth preset temperature, which is 20 °C or more in this embodiment, it is determined that the diagnostic working condition for the cooling capacity of the drive motor inverter 6 is satisfied; otherwise, it is not satisfied.

[0108] (2) Diagnostic steps:

[0109] (2.1) First, wait for the temperature of the drive motor inverter 6 to stabilize. Then, turn off the electric water pump 3 to stop the coolant from flowing. Since the vehicle has been powered off, the drive motor inverter 6 basically stops working, so its heat generation no longer increases. If the temperature of the drive motor inverter 6 stabilizes within the thirteenth preset time, which is 2 minutes in this embodiment, then start the diagnosis of the cooling capacity. If it does not stabilize, abandon this diagnosis;

[0110] (2.2) If the temperature change rate of the drive motor inverter 6 is less than the fifth preset threshold value, it is determined that the temperature of the drive motor inverter 6 is stable. This fifth preset threshold value is obtained by looking up the table TmInvtr_Thd based on the ambient temperature. The horizontal axis of the table is the ambient temperature, and the table output is the temperature change rate threshold value. The temperature change rate of the drive motor inverter 6 is obtained by taking the temperature difference of the drive motor inverter 6 at an interval of the fourteenth preset time, which is 20 seconds in this embodiment, before and after, that is, (temperature 20 seconds ago - current temperature) / 20. The recommended table TmInvtr_Thd is shown in the following table:

[0111]

[0112] (2.3) When the temperature of the drive motor inverter 6 has stabilized, bypass the cooling circuits of the DCDC 4, generator inverter 5, generator 7, and drive motor 8 by controlling the DCDC cooling bypass three-way valve 15, drive motor inverter cooling bypass three-way valve 16, generator cooling bypass three-way valve 18, and drive motor cooling bypass three-way valve 19. Control the drive motor inverter cooling bypass three-way valve 17 to connect the drive motor inverter 6 to the cooling circuit. Then, set the speed of the electric water pump 3 to the maximum and the speed of the cooling fan 2 to the maximum, that is, the entire cooling system cools the drive motor inverter 6 with the maximum cooling capacity. When the fifteenth preset time, which is 1 minute in this embodiment, has passed, if the temperature reduction degree of the drive motor inverter 6 is less than the threshold value TmInvtr_1Thd, it is determined that the cooling capacity of the drive motor inverter 6 is insufficient;

[0113] Among them, the threshold value TmInvtr_1Thd is obtained by looking up the table. The inputs of the table are respectively the initial temperature of the drive motor inverter 6 when the cooling capacity is detected and the ambient temperature, and the output of the table is the temperature reduction degree of the drive motor inverter 6 after 1 minute. Select a brand-new mass-produced drive motor inverter. At each ambient temperature, when the drive motor inverter starts forced cooling with different initial temperatures at the maximum capacity, obtain the temperature reduction degree of the drive motor inverter after 1 minute, and multiply this temperature reduction degree by 1.1 as the final table value.

[0114] It should be noted that the diagnosis of the above five components does not distinguish the order. The diagnosis of the cooling capacity of a component can be carried out first as long as the diagnosis condition of that component is satisfied first. If the diagnosis conditions of multiple components are satisfied during a certain shutdown process, the priorities from high to low are: drive motor > generator > drive motor inverter > generator inverter > DCDC.

[0115] If during the detection process, it is detected that the cooling capacity of any one component has decreased, the relevant fault codes are stored and the driver is reminded to repair the vehicle.

[0116] Compared with the prior art, the significant advantages of this solution are:

[0117] In this solution, specific operations are used to detect whether the cooling effect of each component on the cooling system meets the design expectations, avoiding the motor system working in a relatively high-temperature area for a long time due to the reduction of the cooling capacity, which may lead to the reduction of the motor system performance. This not only improves the product life but also accumulates data for the OEM to improve the relevant design.

[0118] Finally, it should be noted that the above are only preferred examples of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A diagnostic method for the cooling capacity of a dual-motor hybrid motor, characterized in that, In this method, a cooling circuit for diagnosis is included. The cooling circuit includes a radiator, an electric water pump, a DCDC, a generator inverter, a drive motor inverter, a generator, and a drive motor connected in sequence. The drive motor is connected to the radiator. The DCDC, the generator inverter, the drive motor inverter, the generator, and the drive motor are respectively connected with a cooling bypass three-way valve and a temperature sensor; This diagnostic method includes five parts: diagnosis of the cooling capacity of the DCDC, diagnosis of the cooling capacity of the generator inverter, diagnosis of the cooling capacity of the drive motor inverter, diagnosis of the cooling capacity of the generator, and diagnosis of the cooling capacity of the drive motor; The diagnosis of the cooling capacity of the DCDC includes the following steps: (1) Judgment of the diagnostic working condition: (1.1) After the driver powers off the whole vehicle, if the temperature of the DCDC at power-off is higher than the temperature of the DCDC at power-on by more than a first preset temperature, it is judged that the diagnostic working condition for the cooling capacity of the DCDC is satisfied; otherwise, it is judged not to be satisfied; (2) Diagnostic steps: (2.1) After the temperature of the DCDC is stable, turn off the electric water pump. If the temperature of the DCDC is stable within a first preset time, start the diagnosis of the cooling capacity; if it is not stable, abandon this diagnosis; (2.2) If the temperature change rate of the DCDC is less than a first preset threshold value, it is judged that the temperature of the DCDC is stable. The first preset threshold value is obtained by looking up the table DCDC_Thd according to the ambient temperature. The temperature change rate of the DCDC is obtained by taking the difference of the DCDC temperatures before and after a second preset time interval; (2.3) After the temperature of the DCDC is stable, bypass the cooling circuits of the generator inverter, the drive motor inverter, the generator, and the drive motor, and connect the DCDC to the cooling circuit. Then set the speed of the electric water pump to the highest. After a third preset time, if the temperature reduction degree of the DCDC is less than the threshold value DCDC_1Thd, it is judged that the cooling capacity of the DCDC is insufficient. The threshold value DCDC_1Thd is obtained by looking up the table.

2. The method for diagnosing the cooling capacity of a dual-motor hybrid motor according to claim 1, wherein The diagnosis of the cooling capacity of the generator inverter includes the following steps: (1) Judgment of the diagnostic working condition: (1.1) After the driver powers off the whole vehicle, if the temperature of the generator inverter at power-off is higher than the temperature of the generator inverter at power-on by more than a second preset temperature, it is judged that the diagnostic working condition for the cooling capacity of the generator inverter is satisfied; otherwise, it is not satisfied; (2) Diagnostic steps: (2.1) After the temperature of the generator inverter is stable, turn off the electric water pump. If the temperature of the generator inverter is stable within a fourth preset time, start the diagnosis of the cooling capacity; if it is not stable, abandon this diagnosis; (2.2) If the temperature change rate of the generator inverter is less than the second preset threshold, it is determined that the temperature of the generator inverter is stable. The second preset threshold is obtained by looking up the table GmInvtr_Thd based on the ambient temperature. The temperature change rate of the generator inverter is obtained by taking the difference in the temperature of the generator inverter before and after the fifth preset time interval. (2.3) After the temperature of the generator inverter is stable, bypass the cooling circuits of the DCDC, the generator inverter, the generator, and the drive motor, and connect the drive motor inverter to the cooling circuit. Then, set the speed of the electric water pump to the maximum. After the sixth preset time has passed, if the degree of temperature reduction of the drive motor inverter is less than the first threshold TmInvtr_1Thd, it is determined that the cooling capacity of the drive motor inverter is insufficient. The first threshold TmInvtr_1Thd is obtained by looking up the table.

3. The dual-motor hybrid motor cooling capacity diagnosis method according to claim 1, characterized in that The diagnosis of the cooling capacity of the generator includes the following steps: (1) Judgment of the diagnostic working condition: (1.1) After the driver powers off the whole vehicle, if the temperature of the generator at power-off is higher than the temperature of the generator at power-on by more than the third preset temperature, it is determined that the diagnostic working condition for the cooling capacity of the generator is met; otherwise, it is not met. (2) Diagnostic steps: (2.1) After the temperature of the generator is stable, turn off the electric water pump. If the temperature of the generator is stable within the seventh preset time, start the diagnosis of the cooling capacity; otherwise, abandon this diagnosis. (2.2) If the temperature change rate of the generator is less than the third preset threshold, it is determined that the temperature of the generator is stable. The third preset threshold is obtained by looking up the table Gm_Thd based on the ambient temperature. The temperature change rate of the generator is obtained by taking the difference in the temperature of the generator before and after the eighth preset time interval. (2.3) After the temperature of the generator is stable, bypass the cooling circuits of the DCDC, the generator inverter, the drive motor inverter, and the drive motor, and connect the generator to the cooling circuit. Then, set the speed of the electric water pump to the maximum. After the ninth preset time has passed, if the degree of temperature reduction of the generator is less than the second threshold TmInvtr_1Thd, it is determined that the cooling capacity of the generator is insufficient. The second threshold TmInvtr_1Thd is obtained by looking up the table.

4. The method for diagnosing the cooling capacity of a dual-motor hybrid motor according to claim 1, characterized in that, The diagnosis of the cooling capacity of the drive motor includes the following steps: (1) Judgment of the diagnostic working condition: (1.1) After the driver powers off the whole vehicle, if the temperature of the drive motor at power-off is higher than the temperature of the drive motor at power-on by more than the fourth preset temperature, it is determined that the diagnostic working condition for the cooling capacity of the drive motor is met; otherwise, it is not met. (2) Diagnostic steps: (2.1) After the temperature of the drive motor is stable, turn off the electric water pump. If the temperature of the drive motor is stable within the tenth preset time, start the diagnosis of the cooling capacity; otherwise, abandon this diagnosis. (2.2) If the temperature change rate of the drive motor is less than the fourth preset threshold value, it is determined that the temperature of the drive motor is stable. The fourth preset threshold value is obtained by looking up the table Tm_Thd according to the ambient temperature. The temperature change rate of the drive motor is obtained by taking the difference of the drive motor temperatures before and after the eleventh preset time interval. (2.3) After the temperature of the drive motor is stable, bypass the DCDC, the generator inverter, the drive motor inverter, and the generator cooling circuit, and connect the drive motor to the cooling circuit. Then set the speed of the electronic water pump to the highest. When the twelfth preset time has passed, if the degree of temperature reduction of the drive motor is less than the threshold value Tm_1Thd, it is determined that the cooling capacity of the drive motor is insufficient. The threshold value Tm_1Thd is obtained by looking up the table.

5. The method for diagnosing the cooling capacity of a dual-motor hybrid power motor according to claim 1, wherein, The diagnosis of the cooling capacity of the drive motor inverter includes the following steps: (1) Judgment of the diagnosis working condition: (1.1) After the driver powers off the whole vehicle, if the temperature of the drive motor inverter when powering off is higher than the temperature of the drive motor inverter when powering on by more than the fifth preset temperature, it is determined that the diagnosis working condition for the cooling capacity of the drive motor inverter is met; otherwise, it is not met. (2) Diagnosis steps: (2.1) After the temperature of the drive motor inverter is stable, turn off the electronic water pump. If the temperature of the drive motor inverter is stable within the thirteenth preset time, start the diagnosis of the cooling capacity; if it is not stable, abandon this diagnosis. (2.2) If the temperature change rate of the drive motor inverter is less than the fifth preset threshold value, it is determined that the temperature of the drive motor inverter is stable. The fifth preset threshold value is obtained by looking up the table TmInvtr_Thd according to the ambient temperature. The temperature change rate of the drive motor inverter is obtained by taking the difference of the generator inverter temperatures before and after the thirteenth preset time interval. (2.3) After the temperature of the drive motor inverter is stable, bypass the cooling circuits of the DCDC, the generator inverter, the generator, and the drive motor, and connect the drive motor inverter to the cooling circuit. Then set the speed of the electronic water pump to the highest. When the thirteenth preset time has passed, if the degree of temperature reduction of the drive motor inverter is less than the third threshold value TmInvtr_1Thd, it is determined that the cooling capacity of the drive motor inverter is insufficient. The third threshold value TmInvtr_1Thd is obtained by looking up the table.

6. The method for diagnosing the cooling capacity of a dual-motor hybrid motor according to claim 1, wherein, The DCDC, the generator inverter, the drive motor inverter, the generator, and the drive motor are respectively connected with cooling bypass three-way valves and temperature sensors, and the electronic water pump is also connected with a temperature sensor at the inlet of the cooling circuit.

7. The method for diagnosing the cooling capacity of a dual-motor hybrid motor according to claim 1, wherein, The diagnostic processes of the five parts are not in a sequential order. The cooling capacity of the cooling circuit is diagnosed once every time the whole vehicle runs the rated kilometers. After each of the diagnostic processes of the five parts is completed once, it is considered that the diagnosis of the cooling capacity of the cooling circuit is all completed until the next time the whole vehicle runs to the rated kilometers.

8. The method for diagnosing the cooling capacity of a dual-motor hybrid power motor according to any one of claims 1 to 7, characterized in that, A cooling fan is provided on the radiator.

9. A dual-motor hybrid electric motor cooling capacity diagnosis system, characterized in that, The system includes a radiator, a cooling fan, an electric water pump, a DCDC, a generator inverter, a drive motor inverter, a generator, and a drive motor. The DCDC, the generator inverter, the drive motor inverter, the generator, and the drive motor are respectively connected with a cooling bypass three-way valve and a temperature sensor, and the electric water pump is connected with a temperature sensor at the inlet of the cooling circuit. The diagnostic system is used to implement the diagnostic method according to any one of claims 1 to 7.

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