Method for determining temperature of component of power inverter

Abstract

The invention relates to a computer-implemented method for determining the temperature of a first component of a power supply inverter (6), the inverter (6) being connected to a rotating electrical machine (2), the electrical machine (2) comprising a second component (3) different from the first component in which alternating current flows, the method comprising a step of measuring the temperature of the second component by means of a temperature sensor (4), the method is characterized in that it comprises a step of determining (140) the temperature of the first component of the inverter (6) on the basis of the temperature of the second component (3) measured with the temperature sensor (4).

Description

Technical Field

[0001] This invention relates to the temperature of power inverters. Background Technology

[0002] In particular, it relates to a method for determining the initial temperature of components of the power inverter in a vehicle when the vehicle is restarted after a period of parking.

[0003] To avoid malfunctions and potential damage, it is essential to know the temperature of the inverter components. Given that placing temperature sensors in each inverter is difficult and expensive, especially in motor vehicles, the temperature is estimated based on component-specific thermal models and the electrical power supplied to the component.

[0004] However, when a vehicle has been parked for a period of time and then restarted, it is difficult to know the initial temperature of these components. Some of them have low thermal time constants and can cool quickly to the temperature of the inverter coolant. However, components with high thermal time constants, such as DC capacitors, may still exhibit high temperatures upon restarting.

[0005] Typically, as a method for determining the initialization temperature of inverter components with high thermal time constants, the thermal time constant of the component is known, the vehicle's parking time, the last known or estimated temperature of the component before parking occurs, and the initialization temperature of the component is calculated based on these values.

[0006] The drawback of this method is that the parking time stored by the vehicle's internal systems is often inaccurate because it is recorded discretely. When the actual parking time does not match one of the possible discrete values, it leads to an incorrect initial temperature. Another drawback is that if there is a problem with the storage of this value, the last known or estimated temperature before parking may be lost, making it impossible to determine the initial temperature. Summary of the Invention

[0007] The purpose of this invention is to improve the determination of the temperature of inverter components.

[0008] To achieve this objective, a computer-implemented method is provided for determining the temperature of a first component of a power inverter connected to a rotating motor, the motor including a second component distinct from the first component, wherein alternating current flows in the second component. The method includes the following steps:

[0009] - The temperature of the second component is measured by a temperature sensor.

[0010] - The temperature of the first component of the inverter is determined based on the temperature of the second component measured using a temperature sensor.

[0011] In reality, the temperature of a component is caused by its losses. It appears that for some components of a power inverter, the losses are primarily due to the AC power supplied by the inverter. Therefore, even if the inverter and the second component are not thermally connected, the temperature of the first component of the inverter and the temperature of the second component flowing with AC power are correlated. The temperature of the first component can be calculated without sensors located inside the inverter and based on accurate data. In particular, this method does not require estimating parking time or determining the thermal time constant of the component. Therefore, it is simpler and more accurate. It also does not require storing the last known or estimated temperature before parking occurs.

[0012] Generally, the letters "AC" refer to the part through which alternating current can flow, and the letters "DC" refer to the part through which direct current can flow.

[0013] The following are other optional features that can be used individually or in combination.

[0014] Preferably, the first component is a DC link capacitor or a DC bus inverter or an AC interface of the inverter.

[0015] For example, a DC bus inverter is a DC bus arranged to distribute DC current within the inverter. For instance, the DC bus is located inside the inverter and connected to a DC connector. The DC connector can be directly connected to the vehicle's power supply.

[0016] For example, the AC interface is a bus or cable. For example, the AC interface is arranged to distribute AC current inside or outside the inverter. For example, the AC interface is connected to the inverter's power switch.

[0017] Therefore, the temperature of the inverter's DC link capacitor is determined by the motor's temperature. In reality, the losses in the DC link capacitor are mainly due to the alternating current, the same current flowing through the motor.

[0018] Advantageously, the second component is the stator of the electric motor of the rotating electric machine, and the measured temperature is the temperature of the stator of the electric motor.

[0019] In practice, alternating current flows through the stator. Its temperature (primarily due to losses associated with this alternating current) allows for the determination of the temperature of the first component of the inverter.

[0020] Preferably, the temperature of the second component is the first measured temperature, and the method further includes the following steps:

[0021] -A second measurement temperature of the inverter's cooling water is measured via another temperature sensor, and

[0022] - The temperature of the first component of the inverter is determined based on the first and second measured temperatures.

[0023] Therefore, in this example, the temperature of the inverter components also depends on the temperature of the inverter's cooling water.

[0024] Advantageously, the temperature of the first component of the inverter is determined according to the following formula:

[0025]

[0026] Among them, T inverter-component It is the temperature determined by the first component of the inverter, T. distinct-component It is the first measured temperature of the second component, T water It is the second measured temperature of the cooling water, and k is a predetermined value.

[0027] The predetermined value k depends on the specific arrangement and can be calculated or inferred through experiments.

[0028] The present invention also includes a method for determining the initialization temperature of components of a power inverter as its objective, the method comprising the step of determining the initialization temperature of the components according to the aforementioned method when the inverter is initialized after a sleep state.

[0029] Therefore, the method described above allows for the determination of the initialization temperature of the inverter components, particularly after parking occurs, rather than storing parking time and temperature before parking. The initialization temperature of the inverter components is simpler and more accurate because it is based on the temperature of the motor components.

[0030] Preferably, the initialization temperature is a first initialization temperature, and the method includes the following steps:

[0031] - Determine the thermal time constants of the inverter components;

[0032] - Determine the last known temperature of the component;

[0033] - Determine the inverter's sleep time;

[0034] - When the inverter is initialized after hibernation, the second initialization temperature of the inverter components is determined based on the thermal time constant, the last known temperature of the components, and the hibernation time of the inverter.

[0035] - Perform a reasonableness check on the first initialization temperature or the second initialization temperature, respectively, based on the second initialization temperature or the first initialization temperature.

[0036] Therefore, in this example, the temperature of the inverter components is determined by the first method described above, and also by the conventional second method. Thus, the result of the first or second method is examined and can be corrected according to the corresponding second or first method.

[0037] The present invention also includes a computer program comprising instructions which, when executed by a computer, cause the computer to implement the steps of the method described above for determining temperature or the method described above for determining initial temperature.

[0038] The present invention also includes a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to perform the steps of the method for determining temperature described above or the steps of the method for determining initial temperature described above.

[0039] The present invention also aims to provide a system comprising:

[0040] - Power inverter, including the first component

[0041] - A rotating electric motor connected to an inverter and including a second component different from the first component, wherein the second component is capable of flowing alternating current;

[0042] - Temperature sensor, used to measure the temperature of the second component.

[0043] The system is characterized in that it further includes a computer device configured to command the following steps:

[0044] -Measure the first temperature of the second component (3) using a sensor;

[0045] - Determine the temperature of the first component of the inverter based on the first temperature. Attached Figure Description

[0046] The invention will be better understood upon reading the following description, which is given by way of example only and with reference to the accompanying drawings, in which:

[0047] [ Figure 1 [Illustration] is a schematic diagram of a vehicle including the system according to the present invention;

[0048] [ Figure 2 [A] is a schematic diagram of a system including an inverter according to the present invention; and

[0049] [ Figure 3 [Illustration] is a diagram of the method according to the present invention. Detailed Implementation

[0050] Figure 1 A motor vehicle 1 including a rotary motor 2 is shown. In this example, the rotary motor 2 is an electric motor that powers the vehicle 1. Alternatively, any type of rotary motor can be considered in the invention, such as an electric motor that powers the braking system of the vehicle 1.

[0051] The rotary motor 2 includes a stator 3 (not shown in detail) and a rotor. The stator 3 includes a temperature sensor 4 for measuring the temperature of the stator 3.

[0052] The vehicle 1 also includes a battery 5 for powering the rotary motor 2.

[0053] The vehicle 1 also includes an inverter 6 connected between the battery 5 and the rotary motor 2 to convert direct current from the battery 5 into alternating current to power the motor 2, and to convert alternating current from the motor 2 into direct current to charge the battery 5.

[0054] The inverter 6 also includes a computer unit 7 connected to the temperature sensor 3 and the rotary motor 2. The unit 7 includes a computer device for controlling the motor 2 and performing the method 100 described later.

[0055] In unit 7, the conventional computer device includes a processor unit 8 and a computer-readable storage medium 9 including instructions that, when executed by the processor unit 8, cause the unit to implement the steps of method 100. Specifically, the medium 9 includes a computer program 10 that includes instructions that, when executed by a computer or computer device such as the processor unit 8, cause the computer to implement the steps of method 100.

[0056] Inverter 6 also includes a cooling water circuit 11. This circuit is capable of cooling inverter 6 by passing through or around components of inverter 6 in a manner known to those skilled in the art. Details regarding the arrangement of circuit 11 will not be described.

[0057] The inverter 6 also includes a second temperature sensor 12 arranged to measure the temperature of the cooling water flowing in the loop 11.

[0058] Figure 2 Components of inverter 6 are shown. Inverter 6 includes a DC connector 13 connected to battery 5 in a manner not shown. The direct current flowing through the DC connector is referred to as I. DC .

[0059] Inverter 6 includes a DC connector 13 that is connected to and allows direct current I to flow. DC DC bus 14.

[0060] Inverter 6 also includes a DC link capacitor 15 connected to DC bus 14. Alternating current flows through the DC link capacitor 15. This is referred to as I... cap,rms Furthermore, the value of the root mean square (rms) current flowing through the DC link capacitor 15 is provided by the following formula:

[0061]

[0062] Where M represents the modulation index, and Phi represents the angle between the AC voltage and AC current. AC,rms The alternating current I flowing in the stator 3 of the rotating electric motor 2. AC The root mean square current.

[0063] Inverter 6 also includes a DC bus inverter 16, which is connected to a DC link capacitor 15, and through which current I flows. inv Current I inv The root mean square current is called I inv,rms Provided by the following formula:

[0064]

[0065] Inverter 6 also includes a power switch 17 connected to DC bus inverter 16, comprising an insulated gate bipolar transistor (IGBT) or MOSFET, through which alternating current I flows. AC Its root mean square current is I AC,rms This current is the alternating current that will be supplied to motor 2.

[0066] Inverter 6 also includes an AC interface 18, which is connected to the power switch 17 and allows AC power to flow. AC To be provided to rotating motor 2. The AC interface can be a busbar or an AC cable.

[0067] Now for reference Figure 3 This describes an example of a method 100 for determining the initialization temperature of the DC link capacitor 15 of the power inverter 6. Finding this initialization temperature is necessary for appropriately controlling the current transmitted to the rotating motor 2. In practice, a thermal model of the inverter components is calculated to ensure thermal inverter protection. Therefore, the power switch 17 is controlled by unit 7 based on a temperature criterion, which affects the motor 2. An incorrect initialization temperature could, for example, result in insufficient torque (too strong or too weak) in the motor 2.

[0068] Method 100 is implemented by computer unit 7 after the parking time of vehicle 1. During the parking time, rotary motor 2 is turned off and inverter 6 is in sleep mode.

[0069] In step 110, vehicle 1 is restarted. Rotary motor 2 is turned on, and inverter 5 is turned on. The initialization temperature needs to be determined.

[0070] In step 120, unit 7 measures the temperature T of the stator 3 of motor 2 using the first temperature sensor 4 positioned on the stator 3. distinct-component .

[0071] In step 130, unit 7 measures the temperature T of the cooling water 11 of inverter 6 using the second temperature sensor 12.water .

[0072] In step 140, unit 7 determines the T of DC link capacitor 15 using the following formula. interver-component :

[0073]

[0074] k is a coefficient determined by technicians through experimental or design data, because k is specific to the arrangement.

[0075] This formula is based on the fact that, according to the formula mentioned above regarding the current flowing through the components of inverter 5, the losses in stator 3 and DC link capacitor 15 are mainly due to the alternating current I. AC These losses are the cause of the temperature of these components. Therefore, although the DC link capacitor 15 and stator 3 are not thermally connected, their respective temperatures are related.

[0076] Unit 7 has now determined the initial temperature of the DC link capacitor 15 and can now control the inverter 6 based on this temperature. Furthermore, due to any thermal model, the temperature evolution can then be determined by Unit 7 based on this initial temperature to ensure thermal protection of the DC link capacitor 15 without causing abnormal consequences to the torque generated by the motor 2.

[0077] The following steps are additional and optional steps for checking and potentially modifying the initialization temperature that has been found.

[0078] In step 150, unit 7 determines the thermal time constant T of the DC link capacitor 15 of inverter 6. constant This value is specifically stored in the memory of unit 7 because this constant value was determined or known during the design of inverter 6.

[0079] At step 160, unit 7 determines the last known temperature T of DC link capacitor 15. beforesleep Specifically, the last known temperature was determined by Unit 7 using a thermal model before the inverter entered sleep mode when the vehicle was parked.

[0080] In step 170, unit 7 determines the temperature T of the coolant 11 just before the inverter enters sleep mode when vehicle 1 is parked. water,beforesleep .

[0081] In step 180, unit 7 determines the sleep time T of inverter 6. park This means the time interval between the time when inverter 6 switches to sleep mode (when the vehicle is parked) and the time when inverter 6 must be reinitialized after sleep (when vehicle 1 restarts).

[0082] At step 190, unit 7 determines the second initialization temperature T of DC link capacitor 15 based on the following formula. inverter-component-2 :

[0083]

[0084] To enhance safety, at step 200, in this example, unit 6 is based on the second initialization temperature T. inverter-component-2 Perform initialization at the first temperature T inverter-component Reasonableness check.

[0085] A reasonableness check is any method known to a technician that allows checking the validity of a result value based on another reference value. Such a check can lead to a change in the first value that has already been found based on the second value. For example, if a certain threshold for the reasonableness check is exceeded, the initialization is considered unreliable. Therefore, initialization can occur, for example, at worst-case temperatures to ensure thermal protection.

[0086] Steps 160 to 100 can be performed before steps 120 to 150. In this case, then based on the first initialization temperature T... inverter-component For the second initialization temperature T inverter-component-2 Perform a reasonableness check.

[0087] The present invention is not limited to the embodiments shown, and other embodiments will be apparent to those skilled in the art.

[0088] First, the present invention is not limited to the method for determining the initialization temperature. In fact, the relationship between the temperature of the DC link capacitor 15 of the inverter 6 and the temperature of the stator 3 of the rotating motor 2 is not limited to initialization after the sleep mode, so the temperature of the DC link capacitor can be determined at any time.

[0089] Furthermore, the temperatures of the DC bus inverter 16 and AC interface 18, instead of those of the DC link capacitor 15, can be determined using the same formula and adaptation factor k value. In fact, based on the formulas described above for these components, the main losses in these components are also due to the AC current I. AC Therefore, the present invention is not limited to calculating the temperature of the DC link capacitor 15; it can be implemented to determine the temperature of other components of the inverter 6.

[0090] Furthermore, if AC interface 18 is considered part of the rotating motor 2, and if temperature sensor 4 is located on AC interface 18 instead of stator 3, the same method would allow the temperature of DC link capacitor 15 or DC bus inverter 16 to be determined based on the temperature measured on AC interface 18 using a suitable k-value. Therefore, the invention is not limited to measuring the temperature of the stator and can be implemented to measure the temperature of another component of the rotating motor 2 in order to determine the temperature of components of inverter 6.

[0091] Therefore, more generally, the present invention provides a computer-implemented method 100 for determining the temperature of a first component 15 of a power inverter 6 connected to a rotating motor 2, the motor including a second component 3 different from the first component 15, wherein alternating current flows in the second component 3, the method 100 including a step 120 of measuring the temperature of the second component 3 by a temperature sensor 4, and a step 140 of determining the temperature of the first component 15 of the inverter 6 based on the temperature of the second component 3 measured by the temperature sensor 4.

[0092] The present invention also provides a system comprising:

[0093] - Power inverter 6, which includes a first component 15, 16 or 18;

[0094] - Rotary motor 2, which is connected to inverter 6 and includes a second component 3, which is different from the first component 15, 16 or 18, wherein the second component 3 is capable of flowing alternating current;

[0095] - Temperature sensor 4, used to measure the temperature of the second component 3.

[0096] Computer devices 7, 8, and 9 are configured to command the following steps:

[0097] - The first temperature of the second component 3 is measured by sensor 4;

[0098] - Determine the temperature of the first component 15, 16, or 18 of the inverter based on the first temperature.

[0099] List of reference numerals

[0100] 1: Vehicle

[0101] 2: Rotary motor

[0102] 3: Stator of motor 2

[0103] 4: Temperature sensor

[0104] 5: Battery

[0105] 6: Inverter

[0106] 7: Computer Unit

[0107] 8: Processing Unit

[0108] 9: Computer storage media

[0109] 10: Computer Programs

[0110] 11: Cooling water circuit

[0111] 12: Temperature sensor

[0112] 13: DC connector

[0113] 14: DC bus

[0114] 15: DC capacitor

[0115] 16: DC bus inverter

[0116] 17: Power Switch

[0117] 18: AC interface

Claims

1. A computer-implemented method (100) for determining a temperature of a first component (15, 16, 18) of a power inverter (6), the inverter (6) being connected to a rotating electrical machine (2), the electrical machine (2) comprising a second component (3) different from the first component (15, 16, 18), wherein, AC electricity circulates in the second component (3), the method (100) comprises a step (120) of measuring the temperature of the second component by means of a temperature sensor (4), the method (100) is characterized in that it comprises a step of determining (140) the temperature of the first component (15, 16, 18) of the inverter (6) based on the temperature of the second component (3) measured with the temperature sensor (4).

2. The method (100) according to the preceding claim, wherein the first component is a DC link capacitor (15) or a DC bus inverter (16) or an AC interface (18) of the inverter (6).

3. The method (100) according to any of the preceding claims, wherein the second component (3) is a stator of an electric motor of the rotary electric machine (2), the measured temperature being the temperature of the stator (3) of the electric machine.

4. The method (100) according to any of the preceding claims, wherein the temperature of the second component (3) is a first measured temperature, the method further comprising the steps of: - measuring (130) a second measured temperature of cooling water of the inverter (6) by means of another temperature sensor (12), and - determining (140) the temperature of the first component of the inverter (6) based on the first measured temperature and the second measured temperature.

5. The method (100) according to the preceding claim, wherein the temperature of the first component of the inverter (6) is determined according to the following formula: ， wherein T inverter-component is the determined temperature of the first component (15, 16, 18) of the inverter (6), T distinct-component is a first measured temperature of the second component (3), T water is a second measured temperature of the cooling water, and k is a predetermined value.

6. A method (100) for determining an initialization temperature of a component (15, 16, 18) of a power inverter (6), comprising, when the inverter (6) is initialized after a hibernation, the step (140) of determining the initialization temperature of the component (15, 16, 18) according to any one of the preceding claims.

7. The method (100) of claim 6, wherein, the initialization temperature determined according to claim 6 is a first initialization temperature, the method comprising the steps of: - determining (150) a thermal time constant of the component of the inverter; - determining (160) a last known temperature of the component; - determining (180) a hibernation time of the inverter; - determining (190) a second initialization temperature of the component of the inverter, when the inverter is initialized after a hibernation, based on the thermal time constant, based on the last known temperature of the component and based on the hibernation time of the inverter; - performing (200) a plausibility check of the first initialization temperature or of the second initialization temperature, respectively, based on the second initialization temperature or on the first initialization temperature.

8. A computer program (10) comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method (100) according to any one of the preceding claims.

9. A computer-readable storage medium (9) comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method (100) according to any one of claims 1 to 7.

10. A system comprising: - a power inverter (6) comprising a first component (15, 16, 18), - a rotary electric machine (2) connected to the inverter (6) and comprising a second part (3) different from the first part (15, 16, 18), wherein the second part (3) is able to flow alternating current; - a temperature sensor (4) for measuring the temperature of the second part (3), characterized in that the inverter further comprises computer means (7, 8, 9) configured to command the following steps: - measuring a first temperature of the second part (3) by means of the sensor (4); - determining the temperature of the first part (15, 16, 18) of the inverter based on the first temperature.

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