Method and system for correcting the measured winding temperature of an electric machine, in particular of an electric vehicle or a hybrid vehicle

Abstract

A method for correcting the temperature measurement results of a winding of an electric motor (12), in particular an electric vehicle or a hybrid vehicle, is disclosed, wherein a measured value (Tmes) of the temperature of the winding measured by a temperature probe (12b) located on the surface of the winding, a measured value (ω) of the rotation speed of the motor (12) measured by a position sensor (12a), and a measured value (Ieff) of the effective current flowing through an inverter (14) controlling the motor measured by a current sensor (14a) are continuously collected. The measured value of the temperature of the winding is corrected based on the measured value (Tmes) of the temperature of the winding, the measured value (ω) of the rotation speed of the motor (12), the measured value (Ieff) of the effective current, and experimental data previously generated on the motor on a test bench.

Description

Technical Field

[0001] The present invention relates to the field of rotating electrical machines and in particular to the measurement of the temperature of active parts of such machines. Background Art

[0002] In the case of electric machines comprising, in particular, pin windings or toothed or concentric windings, a temperature probe, such as, for example, a negative temperature coefficient sensor, referred to as an NTC (negative temperature coefficient) sensor, is arranged on the outer surface of the winding head or between two pins. The temperature probe is usually covered by a plastic sleeve.

[0003] The measured temperature value deviates from the actual temperature value at the center of the winding, especially for dynamic driving curves. This difference is intensified by the presence of contact resistance between the winding wire and the temperature probe located away from the winding core. Specifically, the resistance reduces the level of heat released by the winding and seen by the temperature probe, resulting in incorrect measurements of the winding temperature.

[0004] Typically, in many motor topologies, the center of the winding constitutes the hottest spot, so it is critical to continuously monitor this point in an electric or hybrid vehicle.

[0005] Underestimation of the winding temperature may lead to an incorrect assessment of the winding health and overheating, which may cause damage to the insulation of, in particular, the copper wires of the windings and thus take the motor out of service or put the operator in danger.

[0006] In order to limit the above problems, it is known to apply a margin to the temperature measurement. However, applying a margin in this way may significantly limit the performance of the electric machine, which may be directly felt by the driver as a limitation on the requested torque.

[0007] There is a need to improve the measurement results of the winding temperature of the motor while ensuring the performance of the motor and overheat protection of the motor. Summary of the invention

[0008] The subject of the invention is a method for correcting temperature measurement results of a winding of an electric motor, in particular of an electric vehicle or a hybrid vehicle, wherein measured values ​​of the temperature of the winding measured by a temperature probe located on the surface of the winding, measured values ​​of the rotational speed of the electric motor measured by a position sensor, and measured values ​​of the effective current flowing through an inverter controlling the electric motor measured by a current sensor are continuously recorded.

[0009] The measured temperature value of the winding is corrected according to the measured value of the temperature of the winding, the measured value of the rotational speed of the motor, the measured value of the effective current, and experimental data previously generated on the motor on the test bench.

[0010] For example, thermocouples were installed at the winding core of the prototype, which is not possible for an electric machine installed in a motor vehicle.

[0011] Advantageously, a first correction value for the temperature is calculated as a function of the measured temperature and a first correction factor from previous tests carried out on the electric machine on the test bench.

[0012] The first correction factor varies according to different measured temperature values ​​of the winding.

[0013] For example, a second correction value for the temperature is calculated based on the measured temperature, an estimate of resistive losses calculated based on the effective current and the speed of the motor, and a second correction factor from previous testing performed on the motor on a test bench.

[0014] The second correction factor varies according to the estimated value of the resistive loss.

[0015] The temperature dependence of these losses due to the change in resistance according to temperature is also considered.

[0016] Advantageously, an initial correction value is calculated by adding the first correction value to the second correction value, and an intermediate correction value is calculated by adding the initial correction value to the measured temperature value.

[0017] The final correction value may then be calculated by filtering this intermediate correction value multiplied by a coefficient using a discrete state integrator.

[0018] According to a second aspect, the invention relates to a system for correcting the temperature of a winding of an electric machine, in particular of an electric or hybrid vehicle, the system comprising a temperature probe located on the surface of the winding, a position sensor and a current sensor for measuring the effective current flowing through an inverter controlling the electric machine.

[0019] The system includes a first module configured to calculate a first correction value of the temperature according to a first correction factor based on the temperature measured by the temperature probe.

[0020] The system further includes a second correction module, which is configured to calculate a second correction value of the temperature based on the temperature measured by the temperature probe and the resistance losses estimated in the module for estimating the resistance losses based on the effective current and the speed of the motor, and the second correction module includes a module for applying a second factor to the measured temperature value (Tmes) based on the estimation of the resistance losses.

[0021] The first correction factor and the second correction factor are from previous tests performed on the motor on a test bench.

[0022] The first correction factor varies according to different measured temperature values ​​of the winding.

[0023] The temperature dependence of these losses due to the change in resistance according to temperature is also considered.

[0024] The second correction factor varies according to the estimated value of the resistive loss.

[0025] The temperature correction system thus makes it possible to effectively readjust the temperature measured at the surface of the winding to the actual temperature at the winding core.

[0026] For example, the system includes a first summer and a second summer, the first summer being configured to add the first correction value and the second correction value to each other and deliver an initial correction value, and the second summer being configured to add the initial correction value to the measured temperature value and deliver an intermediate correction value.

[0027] The system may include means for applying coefficients to the intermediate correction value, and a filtering means including a discrete state integrator and delivering a final correction value.

[0028] The final correction value is then looped back and subtracted in the second summer.

[0029] According to a third aspect, the present invention relates to an electric vehicle or a hybrid vehicle, which comprises at least one motor, an inverter, a power controller intended to control the inverter of the motor, a system for managing the performance of the motor, and the above-mentioned system for correcting the temperature of the winding, which system is intended to be integrated into the power controller and is configured to transmit the correction value of the winding temperature to the system for managing the performance of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other objects, features and advantages of the present invention will become apparent from a reading of the following description, provided by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0031] - Figure 1 Schematically illustrated is an electric vehicle or hybrid vehicle comprising a system for correcting the temperature of a winding according to the invention;

[0032] - Figure 2 Shown in detail Figure 1 A system for correcting the temperature of the windings; and

[0033] - Figure 3 An embodiment of the method according to the invention for correcting the temperature of a winding is shown. DETAILED DESCRIPTION

[0034] As in Figure 1 As shown in , an electric or hybrid vehicle 10 includes at least one electric machine 12 , an inverter 14 , and a power controller 16 of the inverter 14 intended to control the electric machine 12 .

[0035] A position sensor 12 a is installed in the electric motor 12 and makes it possible to measure the value ω of the rotation speed of said electric motor.

[0036] The temperature probe 12 b is arranged on a winding head of a winding (not shown) of the electric machine and measures the temperature Tmes of the winding.

[0037] The current sensor 14 a is installed in the inverter, and makes it possible to measure the effective current Ieff flowing through the inverter 14 .

[0038] The electric or hybrid motor vehicle 10 further comprises a system 20 for correcting the temperature of the windings, which is intended to be integrated into the power controller 16 and transmits a corrected value Tcorr of the winding temperature to the system 18 for managing the performance of the electric machine 12 .

[0039] Figure 2 , a system 20 for correcting the temperature of a winding is shown in detail, the system comprising a first module 21 for correcting the temperature Tmes measured by a temperature probe 12b according to a first correction factor F1 from a previous test performed on a motor on a test bench. The first correction factor F1 is different according to different measured values ​​Tmes of the temperature of the winding.

[0040] The first correction module 21 delivers a first correction value T1 of temperature.

[0041] The system 20 for correcting the temperature of the winding further comprises a second module 22 for estimating the resistance loss P according to the effective current Ieff and the rotation speed ω of the motor 12. J The resistance loss P obtained in module 23 is J The temperature Tmes measured by the temperature probe 12b is corrected by the following equation:

[0042] P J (T) = R(T).Ieff 2 Equation 1

[0043] The second correction module 22 also includes a device for adjusting the resistance loss P JThe module 24 applies a second factor F2 to the measured temperature value Tmes.

[0044] The second correction factor F2 also comes from previous tests performed on the motor on the test bench. The second correction factor F2 is based on the resistive losses P J The estimated value varies.

[0045] The second correction module 22 delivers a second correction value T2 for the temperature.

[0046] The system 20 for correcting the temperature of the winding further comprises a first summer 25 and a second summer 26, the first summer being configured to add the correction values ​​T1, T2 to each other and deliver an initial correction value T3, and the second summer being configured to add the initial correction value T3 to the measured temperature value Tmes and deliver an intermediate correction value T4.

[0047] The system 20 for correcting the temperature of the windings also comprises a module 27 for applying a coefficient Kp to the input of a filtering module 28, which comprises a discrete state integrator and delivers a final correction value Tcorr. The final correction value Tcorr is then looped back and subtracted in the second summer 26. The coefficient Kp is the gain of the filter applied in the module 28.

[0048] The temperature correction system thus makes it possible to effectively readjust the temperature measured at the surface of the winding to the actual temperature at the winding core.

[0049] Figure 3 The flowchart shown shows Figure 2 An exemplary method 30 implemented by the system is shown.

[0050] In the first step 31, the measured value Tmes of the winding temperature measured by the temperature probe 12b, the value ω of the rotation speed of the motor 12 measured by the position sensor 12a, and the measured result Ieff of the effective current flowing through the inverter 14 measured by the current sensor 14a are collected.

[0051] In step 32, a first correction value T1 for the temperature is calculated from the temperature Tmes measured by the temperature probe 12b and from a first correction factor F1 from a previous test performed on the motor on the test bench. The first correction factor F1 is different according to the measured value Tmes of the temperature of the winding. The first correction factor F1 is of the order of a few degrees over the temperature variation margin between -30°C and 160°C.

[0052] In step 33, the resistance loss P is calculated based on the temperature Tmes measured by the temperature probe 12b, the effective current Ieff and the speed ω of the motor 12. JThe second correction value T2 for this temperature is calculated using an estimate of , and a second correction factor F2 from previous tests performed on the motor on the test bench. The order of magnitude of the second correction factor F2 can be a few degrees for smaller losses and tens of degrees for larger losses.

[0053] These losses P due to the change in resistance R according to temperature are also taken into account by the following equation J Dependence on temperature:

[0054] P J (T) = R(T).Ieff 2 Equation 1

[0055] The second correction factor F2 is based on the resistance loss P J The estimated value varies.

[0056] In step 34, an initial correction value T3 is calculated by adding the correction values ​​T1 and T2, and in step 35, an intermediate correction value T4 is calculated by adding the initial correction value T3 and the measured temperature value Tmes.

[0057] Steps 36 and 37 implement a control loop regarding this intermediate correction value T4. In step 36, a coefficient Kp is applied to the error of the intermediate correction value T4, and in step 37, a final correction value Tcorr is calculated by filtering the previous value obtained by multiplying the error by the gain Kp using a discrete state integrator. The z transfer function of this discrete integrator is of the form:

[0058]

[0059] Where T is the sampling period.

[0060] The final correction value is then looped back by Tcorr and, in step 35 , is subtracted from the intermediate correction value T4 .

[0061] A method for correcting the measured temperature with respect to the actual temperature of the winding core is constructed based on experimental measurements previously performed on a prototype and power is supplied thereto. For example, a thermocouple is installed at the winding core of the prototype, which is not possible for a motor installed in a motor vehicle.

[0062] By means of the present invention, the measurement result of the winding temperature of the motor is improved, so that the measurement result is close to the actual value of the temperature at the winding core, while ensuring the performance of the motor and the overheating protection of the motor.

Claims

1. A method for correcting temperature measurements of a winding of an electric motor (12) of an electric vehicle or a hybrid vehicle, wherein: The method continuously collects a measured value (Tmes) of the temperature of the winding measured by a temperature probe (l2b) located on the surface of the winding, a measured value (ω) of the rotational speed of the motor (12) measured by a position sensor (l2a), and a measured value (Ieff) of the effective current flowing through an inverter (14) controlling the motor measured by a current sensor (l4a), characterized in that a first correction value (Tl) of the temperature is calculated based on the measured value (Tmes) of the temperature of the winding and a first correction factor (Fl) from a previous test on the motor on a test bench, and a resistance loss (P) is estimated based on the measured value (ω) of the rotational speed of the motor (12) and the measured value (Ieff) of the effective current. J ), and based on the measured value of the temperature (Tmes) and the resistance loss (P J ) is used to calculate a second correction value (T2) of the temperature, wherein the second correction value (T2) is calculated based on experimental data previously generated on a motor on a test bench by installing thermocouples at the core of the winding of the prototype and the estimated resistance loss (P J ) to apply a second correction factor to the measured value of the temperature of the winding.

2. The method of claim 1, wherein: An initial correction value (T3) is calculated by adding the first correction value (T1) and the second correction value (T2), and an intermediate correction value (T4) is calculated by adding the initial correction value (T3) and the measured value (Tmes) of the temperature.

3. The method of claim 2, wherein: The final correction value (Tcorr) is calculated by filtering the intermediate correction value (T4) multiplied by a coefficient (Kp) using a discrete state integrator.

4. A system for correcting temperature measurements of a winding of an electric motor (12) of an electric vehicle or a hybrid vehicle, the system comprising a temperature probe (12b) located on the surface of the winding, a position sensor (12a) and a current sensor (14a) for measuring an effective current (Ieff) flowing through an inverter (14) controlling the motor, characterized in that: The system comprises a first module (21) configured to calculate a first correction value (Tl) of the temperature according to a value (Tmes) of the temperature measured by the temperature probe (12b) and a first correction factor (Fl), and the system comprises a second correction module (22) configured to calculate a first correction value (Tl) of the temperature according to the value (Tmes) of the temperature measured by the temperature probe (12b) and a first correction factor (Fl). J ) module (23) estimated resistance loss (P J ) to calculate a second correction value (T2) of the temperature, the second correction module (22) comprising a module for calculating the second correction value (T2) of the temperature according to experimental data previously generated on a motor on a test bench by installing thermocouples at the core of the winding of the prototype and the resistance loss (P J ) is a module (24) for applying a second correction factor (F2) to the value of the measured temperature (Tmes).

5. The system as claimed in claim 4, comprising a first summer (25) and a second summer (26), the first summer being configured to add the first correction value (Tl) and the second correction value (T2) to each other and to deliver an initial correction value (T3), and the second summer being configured to add the initial correction value (T3) to the value of the measured temperature (Tmes) and to deliver an intermediate correction value (T4).

6. System as claimed in claim 5, comprising a module (27) for applying a coefficient (Kp) to the intermediate correction value (T4), and a filtering module (28) comprising a discrete state integrator and delivering a final correction value (Tcorr).

7. An electric vehicle or hybrid vehicle (10), comprising at least one electric machine (12), an inverter (14), a power controller (16) intended to control the inverter (14) of the electric machine, a management system (18) for managing the performance of the electric machine (12), and a system (20) as claimed in any one of claims 4 to 6, intended to be integrated into the power controller (16) and configured to transmit a correction value (Tcorr) of the temperature of the winding to the management system (18).

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