Method for classifying the performance of an electric traction machine as a permanent magnet synchronous motor

Abstract

The present invention relates to a method for classifying the performance of an electric traction machine, a permanent magnet synchronous motor (PMSM), coupled to a drive shaft and powered by a battery via an inverter. The method comprises: decoupling the PMSM from the drive shaft (S10); performing a first deceleration test to measure the magnetic flux linkage of the permanent magnets in the PMSM, i.e., the PM flux (S20); performing a second deceleration test to measure the no-load power loss of the PMSM (S30), with the inverter disconnected in the second deceleration test; correlating the PM flux with the no-load power loss in a health parameter of the PMSM (S40), and comparing the health parameter with reference data of known health parameters of a population of PMSMs (S50); and classifying the performance of the PMSM based on the compared health parameter (S60).

Description

Technical Field

[0001] The present invention relates to a method for classifying the performance of an electric traction machine, which is a permanent magnet synchronous motor (PMSM). The invention also relates to a computer program comprising program code components for executing the method, a control device for controlling the operation of a PMSM, an arrangement comprising a PMSM and a control device, and a vehicle. Background Art

[0002] A vehicle typically includes an engine or a machine for propelling the vehicle. The engine can be powered in various ways, such as by liquid or gaseous fuel in an internal combustion engine, or by electricity supplied to an electric motor. Hybrid solutions exist, where, for example, a vehicle is propelled by both an internal combustion engine and an electric motor. Regardless of the approach, an energy storage or energy conversion device (such as a battery) is used to provide the energy required to propel the vehicle.

[0003] One specific type of electric motor is a synchronous electric motor driven by alternating current (AC). In this synchronous electric motor, under steady-state conditions, the rotor and rotating shaft rotate synchronously with the frequency of the supply current. That is, the rotation period is an integer multiple of the AC cycle. The stator of a synchronous electric motor includes multi-phase AC electromagnets that generate a magnetic field that rotates in time with the oscillations of the line current. The rotor of a synchronous electric motor includes permanent magnets or electromagnets and rotates with the magnetic field generated by the stator.

[0004] When permanent magnets are used in the rotor, the synchronous electric motor is called a permanent magnet synchronous motor (PMSM). Permanent magnets (e.g., neodymium magnets) are typically embedded in the rotor to produce a constant magnetic field, and the stator includes stator windings connected to an AC power source to produce a rotating magnetic field. At synchronous speed, the rotor poles are locked to the rotating magnetic field.

[0005] The characteristics of PMSMs of the same design vary slightly from one another. Various tests can be performed to determine the characteristics of a PMSM. For example, performance tests can be performed just before the PMSM is produced at the manufacturing site to verify that the PMSM operates within acceptable tolerances. In addition, so-called online tests performed after the PMSM is installed in the vehicle and online tests performed during normal operation of the PMSM can provide information, for example, on the peak temperature in the PMSM. If the temperature exceeds a critical temperature (Curie temperature), the magnetic field strength of the permanent magnet decreases sharply, and demagnetization may even occur.

[0006] For various reasons (for example, different permanent magnet materials have different properties), it is important to understand the operation of a PMSM relative to its characteristics. For example, temperature characteristics can vary, and typically, the magnetic field strength of a permanent magnet decreases linearly with increasing temperature and increases linearly with decreasing temperature. Therefore, by understanding the temperature characteristics of a PMSM, the efficiency or performance of the PMSM can be improved.

[0007] Although current tests (such as manufacturing field tests and online tests) give important information about PMSM characteristics, the characteristics of PMSM need to be further improved. Summary of the Invention

[0008] It is an object of the present invention to alleviate, at least to some extent, the disadvantages discussed above with respect to known PMSMs and their characteristics.

[0009] According to at least a first aspect of the present invention, there is provided a method for classifying the performance of an electric traction machine being a permanent magnet synchronous motor (PMSM), the PMSM being coupled to a drive shaft and powered by a battery via an inverter. The method comprises:

[0010] -Decouple the PMSM from the drive shaft;

[0011] - performing a first deceleration test to measure the flux linkage of the permanent magnets in the PMSM, i.e., the PM flux;

[0012] - Performing a second deceleration test to measure the no-load power loss of the PMSM, with the inverter disconnected;

[0013] - Correlating PM flux with no-load power loss in a PMSM health parameter and comparing this health parameter with reference data of known health parameters for a population of PMSMs;

[0014] - Classifying the performance of the PMSM based on the compared health parameters.

[0015] Thus, an efficient method for classifying PMSMs by comparing them to reference data is provided. For example, a PMSM can be classified based on excessive no-load power loss compared to the PM flux, or a PMSM can be classified based on the likelihood of premature failure by comparing health parameters to known health parameters of a population of PMSMs, including empirical data indicating health parameters that indicate premature failure.

[0016] The method of the present invention is advantageous because it can improve the predictive maintenance of PMSMs. Consequently, it can increase vehicle reliability and range. Furthermore, the method makes it possible to predict degradation of drivetrain performance before a vehicle fails. That is, the results of the classification of the PMSM's performance provide, for example, changes in the PMSM's internal losses and deviations from reference data for a population of similar PMSMs that can be detected early. Furthermore, the health parameters can be used as baseline values ​​or reference health parameters for subsequent online testing of the PMSM. For tracking and optimization purposes, the health parameters for both the current PMSM and the reference data can be stored, for example, in a cloud database.

[0017] According to at least one example embodiment, the method includes determining a temperature of a PMSM or at least a temperature of a permanent magnet of the PMSM and correlating the PM magnetic flux to the temperature.

[0018] Because the PM flux is often dependent on the temperature of the PMSM or the permanent magnets within it, including the PM flux temperature in the health parameters further improves PMSM classification. The determined temperature and its correlation with the PM flux can also be used as a reference temperature and, for example, during online testing or online measurements (i.e., during normal operation of the PMSM), to estimate when the temperature may reach a point at which the permanent magnets may be damaged, i.e., the critical temperature or Curie temperature.

[0019] According to at least one example embodiment, the method comprises:

[0020] - Before the first deceleration test, determine the steady-state temperature of the permanent magnets in the PMSM.

[0021] Therefore, the PM flux can be determined for a specific temperature and any changes in the PM flux with respect to temperature changes can be ignored. This can further improve the classification of the PMSM.

[0022] According to at least one example embodiment, the PMSM is coupled to the drive shaft via a gearbox, and decoupling the PMSM from the drive shaft may include decoupling the PMSM from the gearbox.

[0023] According to at least one example embodiment, the method comprises:

[0024] - measuring the temperature inside the PMSM, such as in the stator windings of the PMSM, and the temperature outside the PMSM, such as in the drive shaft or gearbox;

[0025] - Comparison of the measured temperatures inside and outside the PMSM by means of the compared temperature parameters,

[0026] - determining a steady-state temperature of the PMSM and a permanent magnet in the PMSM in response to determining that the compared temperature parameter is below a threshold temperature difference.

[0027] Therefore, it can be confirmed that the steady-state temperature of the PMSM has been reached. By confirming that the steady-state temperature of the PMSM has been reached, the PM flux can be determined for a specific temperature.

[0028] According to at least one example embodiment, the PMSM is operated by a current controller, and the first deceleration test and / or the second deceleration test is performed by accelerating the PMSM to a base speed, and thus, a current reference of the current controller is set to zero.

[0029] Thus, at least for the first deceleration test, the effects of any magnetic field due to the current in the stator windings can be ignored. Consequently, the determination of the PM flux can be improved. That is, by setting the current reference of the current controller to zero, the current fed to the PMSM is zero. The current controller can, for example, be included in a control device configured to control the operation of the PMSM.

[0030] According to at least one example embodiment, the PM flux is determined by a ratio of a voltage reference of a current controller to the electrical angular velocity.

[0031] Thus, a simple and effective method for determining PM flux is provided. The electrical angular velocity is derived, for example, from a position sensor disposed in the PMSM's rotating shaft (i.e., position is derived via a rotor position sensor). The PM flux can be continuously measured over a period of time during deceleration of the PMSM and then averaged over this period. For example, the PM flux can be averaged from a base speed to a state where the PMSM's rotating shaft is close to zero (i.e., nearly stationary). The base speed can be, for example, 4000 to 5000 rpm.

[0032] According to at least one example embodiment, the no-load power loss is determined by multiplying the loss torque of the PMSM by the mechanical angular velocity.

[0033] Thus, a simple and effective method for determining no-load power loss is provided. The mechanical angular velocity can be determined by a position sensor arranged in the rotating shaft of the PMSM. If the control device is configured to provide the result of the position sensor in terms of electrical angular velocity, it should be divided by the number of pole pairs in order to obtain the mechanical angular velocity.

[0034] According to at least one example embodiment, the loss torque is estimated by multiplying the magnitude of the acceleration by the moment of inertia of the rotating shaft of the PMSM.

[0035] Thus, a simple and efficient method of determining the loss torque is provided.

[0036] The moment of inertia of the rotating shaft can be known in advance or can be estimated from the electromagnetic torque during the torque performance test. During the torque performance test, the PMSM is accelerated to the base speed, after which current (q-axis current) is fed to the PMSM in a controlled manner to decelerate the PMSM to 0 and then accelerate the PMSM again. In more detail, the torque of the unloaded PMSM can be described as:

[0037]

[0038] Where J is the moment of inertia of the rotation axis, (dω m ) / dt is the change of mechanical angular velocity over time, T em (i d ,i q ) is used as the dq current (i d 、i q ) is a function of the electromagnetic torque, and T loss is the loss torque, T loss The sign changes depending on whether the PMSM is operated as a motor or as a generator (i.e., deceleration and acceleration of the PMSM). By measuring the PMSM operating both as a motor and as a generator, and for the same magnitude of the mechanical angular velocity, the following relationship can be established:

[0039]

[0040] The terms "motor" and "generator" indicate whether the PMSM is operating as a motor or a generator. Therefore, the moment of inertia J can be estimated by the following formula:

[0041]

[0042] The electromagnetic torque T em It can be estimated from the turn-link flux as follows, T em =(i q *ψ d -i d *ψ q )*1.5*n, where n is the number of pole pairs. Therefore, the no-load power loss P can be determined from the loss torque of the PMSM (estimated by multiplying the magnitude of the acceleration by the moment of inertia of the PMSM's rotating shaft) and the mechanical angular velocity. loss :

[0043]

[0044] According to at least one example embodiment, the magnitude of the acceleration depends on the PM flux, and correlating the PM flux with the no-load power loss in the health parameter of the PMSM includes making the PM flux and the no-load power loss dependent on each other.

[0045] Therefore, by making the magnitude of acceleration depend on the PM magnetic flux, the no-load power loss is made dependent on the magnitude of acceleration, and the no-load power loss becomes dependent on the PM magnetic flux.

[0046] According to at least one example embodiment, the health parameter is a multi-valued parameter, and the known health parameter of the reference data is a corresponding multi-valued parameter.

[0047] That is, the health parameter includes more than one unit or entity. For example, a first health parameter includes a first value of PM flux and a first value of no-load power loss, while a second health parameter includes a second value of PM flux and a second value of no-load power loss, where the first and / or second values ​​of PM flux and no-load power loss are different.

[0048] According to at least one example embodiment, the method includes

[0049] - Determining whether the compared health parameters meet preset criteria, and classifying the performance of the PMSM if the health parameters meet the preset criteria.

[0050] Thus, the classification may be performed conditionally based on preset criteria. According to at least one example embodiment, the method may include determining whether the compared health parameter is less than (or greater than) a threshold value, and in response to determining that the compared health parameter is less than (or greater than) the threshold value, classifying the performance of the PMSM into a specific category.

[0051] According to at least one example embodiment, the method includes

[0052] - determining whether the compared health parameter meets a preset standard, and classifying the performance of the PMSM if the health parameter meets the preset standard, wherein the classification is associated with reduced performance of the PMSM.

[0053] Therefore, in other words, the method includes determining whether the compared health parameter meets a preset standard, for example, determining whether the compared health parameter is less than (or greater than) a threshold value related to the performance of the PMSM, and if the health parameter meets the preset standard (i.e., is determined to be less than (or greater than) the threshold value), then classifying the performance of the PMSM as reduced performance of the PMSM.

[0054] Thus, for example, based on no-load power loss, a PMSM can be classified at least by its performance. If the no-load power loss is relatively large (compared to known health parameters of the PMSM population), then the PMSM may be classified as a low-performance PMSM and, therefore, may require replacement or repair.

[0055] According to at least one example embodiment, the PMSM is installed in a vehicle, and the method is performed offline when the vehicle is at rest.

[0056] Therefore, the offline performance of the method described herein is different from the online performance performed during normal operation of the PMSM. Normal operation of the PMSM refers here to the operation of the PMSM to perform its normal tasks, such as propelling the vehicle or providing power to auxiliary loads (e.g., bodybuilder loads). The offline performance of the method described herein is also different from the offline performance performed before the PMSM is installed in the vehicle, the latter being performed, for example, at the manufacturing site of the PMSM. The method of the present invention (wherein the PMSM is installed in the vehicle and the method is performed offline when the vehicle is at rest) can reveal details and performance of the PMSM that would not be revealed before the PMSM is installed in the vehicle and / or when the method is performed online.

[0057] According to at least one example embodiment, the method comprises:

[0058] - Perform a stationary characterization of the PMSM to estimate the turn-link flux as a function of current;

[0059] - adding the PM flux to the estimated turn linkage flux to provide flux characteristics of the PMSM, which are included in the classification of the performance of the PMSM;

[0060] -Adapting the control parameters of the PMSM based on the flux characteristics.

[0061] Therefore, by adapting the control parameters of the PMSM, the operation of the PMSM can be improved based on the flux characteristics. For example, the operation of the PMSM can be improved with respect to how the current in the PMSM is controlled. It should be understood that the adaptation of the control parameters can be performed by at least adapting the current control. Current control may mean updating one or more control parameters of the PMSM. In addition, current control can be adapted over time and thus may include multiple adaptations of the control parameters. According to at least one example embodiment, the adaptation of the control parameters may be referred to as the adaptation of at least one control parameter. According to at least one example embodiment, the adapted control parameter is the current control.

[0062] It should be understood that the term flux linkage or PM flux here refers to the flux of the permanent magnets when it is independent of current (i.e., there is no current in the stator windings), and that turn-link flux here refers to the flux as a function of current. Both terms can be simply referred to as flux linkage, the former (PM flux) being independent of current, and the latter being dependent on flux as a function of current.

[0063] According to at least one example embodiment, the PM flux, as a single value, is added to at least the turn-link flux on the d-axis of the dq coordinate system (explained in more detail below). Thus, operating the PMSM with dq currents results in the turn-link flux being a function of the current along two perpendicular axes (i.e., the d-axis and the q-axis) known to those skilled in the art.

[0064] For a certain step size n, the turn-link flux Ψd, Ψq as a function of current (dq current) can be estimated by the following formula:

[0065]

[0066]

[0067] Where L is the differential inductance given by the impedance (given by the current and PM flux) multiplied by the sine of the phase change divided by the electrical angular velocity. Therefore, if the PM flux is known or measured, the PMSM's flux as a function of the d-axis current can be estimated at rest. The PMSM's rotating axis is prevented from rotating (e.g., due to being locked by the gearbox). By combining the DC current with the AC current, the dynamic inductance at different operating points can be obtained while taking into account the saturation effect of the iron.

[0068] In more detail, and according to one example embodiment, the derivation of the differential inductances at different saturation levels can be determined by the following procedure based on an orthogonal reference frame spanning 360 electrical degrees (from one north pole to the next), where the so-called d-axis is aligned with the permanent magnet flux and the so-called q-axis is phase-shifted by 90 degrees relative to the PM flux. This reference frame is referred to as the dq frame.

[0069] For an appropriate current control procedure, specific dq current references are considered: two DC reference currents that saturate the iron (one reference on the d axis and one reference on the q axis); and an AC reference current that oscillates at a predefined frequency on the d axis or the q axis. The current controller implements these currents by generating appropriate dq voltage references for the inverter. To begin estimating the differential inductance, the DC component of the dq voltage reference from the current controller is removed for post-processing calculations (e.g., using a high-pass filter). The amplitudes of the current and voltage and the phase angle between them (for both d and q) are obtained by, for example, discrete Fourier transform. The amplitude and phase angle are used to derive different differential inductances. For each combination of DC currents, the algorithm derives four inductances:

[0070] L d (i d ,i q), i.e., the proportionality factor between the change in d-axis current and the change in the turn-linkage flux on the d-axis, derived when the AC component of the current is on the d-axis. The inductance is given by the ratio of the amplitudes of the d-axis voltage and current divided by the angular frequency and multiplied by the sine of the phase angle.

[0071] L q (i d ,i q ), i.e., the proportionality factor between the change in q-axis current and the change in the winding flux on the q-axis, derived when the AC component of the current is on the q-axis. The inductance is given by the ratio of the amplitudes of the q-axis voltage and current divided by the angular frequency and multiplied by the sine of the phase angle.

[0072] L dq (i d ,i q ), i.e., the proportionality factor between the change in q-axis current and the change in the winding flux on the d-axis, derived when the AC component of the current is on the q-axis. The inductance is given by the ratio of the amplitudes of the d-axis voltage and the q-axis current divided by the angular frequency.

[0073] L qd (i d ,i q ), i.e., the proportionality factor between the change in d-axis current and the change in the winding flux on the q-axis, derived when the AC component of the current is on the d-axis. The inductance is given by the ratio of the amplitudes of the q-axis voltage and the d-axis current divided by the angular frequency.

[0074] The differential inductance is obtained for all dq DC current combinations of interest. The differential inductance can then be used to derive the turn-linkage flux for the dq current combination under consideration, for example, as described in more detail below.

[0075] At zero DC current, the turn-link flux on the q-axis is zero because the current is zero and the turn-link flux on the d-axis is the PM flux. Subsequently, the DC current is changed, and the appropriate inductance derived as described above is used to estimate how much the turn-link flux (on both the d-axis and the q-axis) changes as a function of the current change (inductance is the proportional factor between the current change and the turn-link flux change). The turn-link flux for the new current combination is saved. Subsequently, the current is changed again, and the turn-link flux for the new current combination is the flux of the previous current combination plus the flux change caused by the current step. The flux change is estimated by the appropriate inductance derived as described above. The turn-link flux for this particular current combination is saved. Subsequently, the same procedure is repeated for all current combinations as described in the previous step until the turn-link flux for all current combinations is obtained.

[0076] According to at least one example embodiment, the classification of the performance of the PMSM is used to adapt control parameters of the PMSM.

[0077] Thus, by adapting the control parameters of the PMSM, the operation of the PMSM can be improved based on the classification. For example, the control parameters can be compared with reference data of known control parameters of a population of PMSMs. According to at least one example embodiment, the flux characteristics are included in the health parameters of the PMSM.

[0078] According to a second aspect of the present invention, there is provided a computer program comprising program code components for executing the method of the first aspect of the present invention when the program is run on a computer.

[0079] According to a third aspect of the present invention, there is provided a computer readable medium carrying a computer program, the computer program comprising program code components for executing the method of the first aspect of the present invention when the program product is run on a computer.

[0080] The effects and features of the second and third aspects of the present invention are largely similar to those described above in conjunction with the first aspect of the present invention. The embodiments mentioned in relation to the first aspect of the present invention are largely compatible with the second and third aspects of the present invention.

[0081] According to a fourth aspect of the present invention, there is provided a control device for controlling the operation of an electric traction machine being a permanent magnet synchronous motor (PMSM), the PMSM being coupled to a drive shaft and powered by a battery via an inverter. The control device is configured to:

[0082] -Decouple the PMSM from the drive shaft;

[0083] - performing a first deceleration test to measure the flux linkage of the permanent magnets in the PMSM, i.e., the PM flux;

[0084] - Performing a second deceleration test to measure the no-load power loss of the PMSM, with the inverter disconnected;

[0085] - Correlating PM flux with no-load power loss in a PMSM health parameter and comparing this health parameter with reference data of known health parameters for a population of PMSMs;

[0086] - Classifying the performance of the PMSM based on the compared health parameters.

[0087] According to at least one example embodiment, the control device is configured to perform the method described with respect to the first aspect of the present invention, or any of the steps thereof. According to at least one example embodiment, the control device is programmed with a computer program according to the second aspect of the present invention. According to at least one example embodiment, the control device comprises a computer-readable medium according to the third aspect of the present invention.

[0088] Therefore, the effects and features of the fourth aspect of the present invention are largely similar to those described above in conjunction with the first aspect of the present invention.The embodiments mentioned in relation to the first aspect of the present invention are largely compatible with the fourth aspect of the present invention.

[0089] According to at least one example embodiment, the control device is further configured to:

[0090] -Provide the flux linkage of the permanent magnets in the PMSM, i.e., PM flux;

[0091] - Perform a stationary characterization of the PMSM to estimate the turn-link flux as a function of current;

[0092] - Adding the PM flux to the estimated turn-link flux to provide the flux characteristics of the PMSM;

[0093] -Adapting the control parameters of the PMSM based on the flux characteristics.

[0094] According to a fifth aspect of the present invention, there is provided an arrangement. The arrangement comprises

[0095] an electric traction machine being a permanent magnet synchronous motor (PMSM), connectable to a drive shaft of the vehicle and configured to be powered by a battery via an inverter; and

[0096] - A control device according to a fourth aspect of the invention.

[0097] This arrangement may be referred to as a PMSM arrangement.

[0098] According to at least one example embodiment, the arrangement includes a drive shaft configured to transfer motion from the PMSM to wheels or other propulsion means of the vehicle, and optionally a gearbox arrangement between the PMSM and the drive shaft.

[0099] According to at least one example embodiment, the arrangement comprises a first temperature sensor, which is arranged in the PMSM, such as in a stator or stator winding of the PMSM, and is configured to measure the temperature inside the PMSM. According to at least one example embodiment, the arrangement comprises a second temperature sensor, which is arranged outside the PMSM, for example in a drive shaft or an optional gearbox, and is configured to measure the temperature outside the PMSM.

[0100] According to a sixth aspect of the present invention, there is provided a vehicle comprising an arrangement according to the fifth aspect of the present invention.

[0101] Therefore, the effects and features of the fifth and sixth aspects of the present invention are largely similar to those described above in conjunction with the first aspect of the present invention. The embodiments mentioned with respect to the first aspect of the present invention are largely compatible with the fifth and sixth aspects of the present invention.

[0102] The order of the method steps described in this disclosure is not limited to the order described in the first aspect of the invention. One or more of these steps may be interchanged or occur in a different order without departing from the scope of the invention. However, according to at least one example embodiment, the method steps are performed in the sequential order described in the first aspect of the invention.

[0103] Other advantages and features of the present disclosure are disclosed and discussed in the following description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] With reference to the accompanying drawings, the following is a more detailed description of embodiments of the invention cited as examples.

[0105] In the attached figure:

[0106] Figure 1 is a schematic side view of a vehicle according to an example embodiment of the present invention;

[0107] Figure 2A is a schematic diagram of a PMSM arrangement according to an example embodiment of the present invention, the PMSM arrangement including a PMSM and a control device;

[0108] Figure 2B yes Figure 2A an enlarged view of a cross section of the PMSM in FIG; and

[0109] Figure 3 is a flowchart illustrating the steps of a method according to an example embodiment of the invention. DETAILED DESCRIPTION

[0110] Reference Figure 1, a vehicle 1 is disclosed, which is embodied here as a heavy truck 1, for which a method, a permanent magnet synchronous motor PMSM 20 and / or a PMSM arrangement 10 disclosed in the present invention are advantageous. However, the method, the PMSM 20 or the PMSM arrangement 10 may also be implemented in other types of vehicles, such as in buses, light trucks, passenger cars, marine applications, etc. The vehicle 1 is an electric vehicle, such as a fully electric vehicle or a hybrid vehicle, comprising at least one electric machine 20 as a PMSM, an energy storage system 30 comprising an energy storage or energy conversion device (typically a battery or a fuel cell), the energy storage system 30 being arranged and configured to power the PMSM 20, typically via a DC-AC converter (inverter). The vehicle 1 typically also comprises other parts of the powertrain, such as a transmission, a drive shaft and wheels ( Figure 1 Not shown in detail). Figure 1 As seen in FIG, the PMSM 20 is controlled by a control device 3 , which is included in an ECU of the vehicle 1 , for example.

[0111] Figure 2A is a schematic diagram of a PMSM arrangement 110 comprising an electric traction machine 120 as a permanent magnet synchronous motor PMSM 120. The PMSM arrangement 110 and the PMSM 120 may correspond, for example, to Figure 1 The PMSM 10 and PMSM 20 of the vehicle 1 are arranged in FIG. The PMSM 120 is connected to the drive shaft 140 of the vehicle and is Figure 2A 150. The drive shaft 140 is generally configured to transmit motion from the PMSM 120 to the wheels or other propulsion means of the vehicle via the gearbox 150. Thus, the PMSM 120 is configured to propel the vehicle. In addition, the PMSM 120 is powered by at least one battery 160 or other energy storage or energy conversion device via an inverter 170 (such as a DC-AC converter). The operation of the PMSM 120 is controlled by a control device 103, which corresponds to, for example, Figure 1 The control device 103 typically comprises a current controller configured to control the current supplied by the battery 160 to the PMSM 120 via the inverter 170 .

[0112] exist Figure 2B , a cross section of a PMSM 120 is shown. Here, the permanent magnets 122 of the rotating shaft 124 are shown, as well as the stator 126 and the stator winding 128. The control device 103 is configured to control at least the current fed to the stator winding 128 via the inverter 170 in a manner known to those skilled in the art. Figure 2B The illustration of the PMSM 120 in FIG. 1 is schematic, and other types of configurations of PMSMs are within the scope of the present invention.

[0113] Now refer to Figure 3 The flowchart details the process for controlling a PMSM (such as Figure 1 、 Figure 2A and Figure 2B Assume that the PMSM is coupled to a drive shaft (such as, Figure 2A of the drive shaft 140) and is powered by the battery via an inverter such as, Figure 2A Therefore, the method is performed on a PMSM installed in a vehicle and is performed offline when the vehicle is at rest.

[0114] In an optional step S1 (eg, as a first step S1), a steady-state temperature of a permanent magnet in the PMSM is determined. The optional first step S1 may be performed, for example, by the following sub-steps:

[0115] In a first sub-step S3, the temperature inside the PMSM, for example the temperature in the stator windings of the PMSM, and the temperature outside the PMSM, for example the temperature in the drive shaft or the gearbox, are determined (e.g., measured). The temperature outside the PMSM is measured at least somewhere along the powertrain downstream of the PMSM, but typically upstream of the propulsion device (e.g., wheels), for example, along the transmission.

[0116] In a second sub-step S5, the measured temperatures inside and outside the PMSM are compared by means of a compared temperature parameter.The compared temperature parameter may simply be represented by any difference between the measured temperatures inside and outside the PMSM.

[0117] In a third sub-step S7, in response to determining that the compared temperature parameter is below a threshold temperature difference, a steady-state temperature of the PMSM and the permanent magnets in the PMSM is determined. That is, if the difference between the measured temperatures inside and outside the PMSM is below a set threshold, for example, 2° C. below, then it is assumed that the steady-state temperature of the PMSM and the permanent magnets has been achieved.

[0118] In step S10 (eg, as a second step S10), the PMSM is decoupled from the drive shaft. This can be performed, for example, by decoupling in a gearbox.

[0119] In step S20 (eg, as a third step S20), a first deceleration test is performed to measure the flux linkage of the permanent magnets in the PMSM, ie, the PM flux. The permanent magnets are shown, for example, in FIG. Figure 2B The first deceleration test is usually performed by: using a current controller (which is usually included in a control device (such as, Figure 12 ) is configured to control the operation of the PMSM and the power supply to the PMSM from the battery. The PMSM is accelerated to a base speed (e.g., 4000 to 5000 rpm), so the current reference of the current controller is set to zero. Because the current reference is set to zero, the PMSM decelerates and eventually comes to a standstill. The magnetic flux linkage is measured as described earlier in this document.

[0120] In step S30 (e.g., as a fourth step S30 typically performed after step S20), a second deceleration test is performed to measure the PMSM's no-load power loss, with the inverter disconnected. Corresponding to the first deceleration test, the second deceleration test is typically performed by accelerating the PMSM to a base speed (e.g., 4000 to 5000 rpm) via a current controller (powering the PMSM via a battery), whereby the current controller's current reference is set to zero and the inverter is disconnected; and / or simply disconnecting the inverter, whereby the current to the PMSM automatically drops to zero. The inverter can be disconnected from the PMSM via a switching device known in the art. When the PMSM's current is zero, the PMSM decelerates and eventually comes to a standstill. The PMSM's no-load power loss is measured as previously described herein and will only be briefly summarized here. The PM magnetic flux can be determined by the ratio of the current controller's voltage reference to the electrical angular velocity. The electrical angular velocity can be determined, for example, by a position sensor in the PMSM's rotating shaft. Additionally, the no-load power loss can be determined by multiplying the loss torque of the PMSM by the mechanical angular velocity, where the loss torque is estimated by multiplying the magnitude of the acceleration by the moment of inertia of the PMSM's rotating axis, which can be known or estimated as described earlier in this document.

[0121] In step S40 (e.g., as the fifth step S40), the PM flux and the no-load power loss are correlated in the PMSM health parameters. This step is preferably performed by the control device, and the health parameters are stored in a memory connected to the control device. The health parameters may, for example, be multi-valued parameters that include at least the PM flux and the no-load power loss as separate values, and may also include an ID reference of the PMSM and the temperature present during the first deceleration test and / or the second deceleration test. Because the magnitude of acceleration depends on the PM flux, correlating the PM flux and the no-load power loss in the PMSM health parameters includes making the PM flux and the no-load power loss mutually dependent.

[0122] In step S50 (e.g., as a sixth step S50), the health parameters are compared with reference data of known health parameters of a PMSM population. The PMSM population preferably includes health parameters of corresponding PMSMs (e.g., at least 10, 20, or 50 PMSMs). The known health parameters preferably correspond to the health parameters of the PMSMs because they are set in a corresponding manner and include at least PM flux and no-load power loss, and possibly also temperature data.

[0123] In step S60 (e.g., as the seventh step S60), the performance of the PMSM is classified based on the compared health parameters. That is, by comparing the health parameters of the PMSM with the known health parameters of the corresponding PMSM, the corresponding PMSM is classified based on at least its health parameters (e.g., a PMSM whose health parameters indicate normal performance is classified as "normal performance," and a PMSM whose health parameters indicate reduced performance is classified as "reduced performance"). Thus, the PMSM can be classified based on at least whether it is operating according to normal performance or reduced performance.

[0124] In step S70 (eg, as the eighth step S70), it is determined whether the compared health parameter meets a preset standard. The preset standard may be based on whether the compared health parameter is less than or greater than a preset threshold, for example.

[0125] In step S80 (eg, as ninth step S80), the performance of the PMSM is classified based on whether the health parameter meets a preset standard. For example, as described earlier, the classification may be associated with a reduced performance of the PMSM.

[0126] In step S90 , which may be performed at any time during the method (eg, as a tenth step S90 ), a stationary characterization of the PMSM is performed to estimate the winding flux (Ψd, Ψq) as a function of current. The winding flux may be determined as described earlier herein.

[0127] In step S100 (e.g., as an eleventh step S100), which may be performed after steps S90 and S20, the PM flux is added to the estimated winding flux to provide a flux characteristic of the PMSM. The flux characteristic can be included in a classification of the PMSM's performance and, for example, in a PMSM health parameter. The PM flux, as a single value, is added to at least the winding flux of the d-axis.

[0128] In step S110 (e.g., as the twelfth step S110), which is performed after step S100, the control parameters of the PMSM are adapted based on the flux characteristics. This can be achieved, for example, by the control device 3, 103 and its current controller. Therefore, because the flux characteristics can be included in the classification of the performance of the PMSM, the classification of the performance of the PMSM can be used to adapt the control parameters of the PMSM.

[0129] In the aforementioned embodiment described Figure 3 The order of the steps in the method is only an example and is not necessarily limited to the order described. The order of the steps can be switched, and parts of some steps can also be omitted.

[0130] Return to Figure 2A , the control device 103 may be configured to perform a reference Figure 3 Therefore, the control device 103 may be configured to at least:

[0131] - Separate the PMSM 120 from the drive shaft 150 as shown in the reference Figure 3 As described in step S10;

[0132] - Perform a first deceleration test to measure the flux linkage of the permanent magnets 122 in the PMSM 120, i.e., the PM flux, as shown in the reference Figure 3 As described in step S20;

[0133] - Perform a second deceleration test to measure the no-load power loss of the PMSM 120, in which the inverter 170 is disconnected, as shown in FIG. Figure 3 As described in step S30;

[0134] - Correlating PM flux with no-load power loss in a health parameter of the PMSM 120 and comparing the health parameter with reference data of known health parameters of a PMSM population, such as a reference Figure 3 As described in steps S40 and S50;

[0135] - Classify the performance of PMSM based on the health parameters compared, such as reference Figure 3 As described in step S60.

[0136] It should be understood that the present invention is not limited to the embodiments described above and illustrated in the accompanying drawings; in fact, those skilled in the art will recognize that numerous changes and modifications are possible within the scope of the appended claims.

[0137] Moreover, variations on the disclosed embodiments may be understood and effected by those skilled in the art in practicing the inventive concept, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0138] It should be understood that the control device 3, 103 may not need to be a single unit, but its functions may be divided into different, independent control units or control devices, and some functions may naturally be performed as calculations in a remote server or through cloud computing. It should also be understood by those skilled in the art that the control device 3, 103 may refer to a combination of analog and digital circuits, and / or one or more processors configured with program software and / or firmware stored in a memory, for example, which, when executed by the one or more processors, performs the combined Figure 3 One or more of these processors and other digital hardware may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several independent components, whether packaged separately or assembled into a system on a chip (SoC).

Claims

1. A method for classifying the performance of an electric traction machine being a permanent magnet synchronous motor (PMSM), the PMSM being coupled to a drive shaft and powered by a battery via an inverter, the method comprising: - separating the PMSM from the drive shaft (S10); - performing a first deceleration test to measure the flux linkage of the permanent magnets in the PMSM, i.e., PM flux (S20); - performing a second deceleration test to measure the no-load power loss of the PMSM (S30), in which the inverter is disconnected; - correlating the PM flux and the no-load power loss in the health parameters of the PMSM (S40), and comparing the health parameters with reference data of known health parameters of a PMSM population (S50); - Classifying the performance of the PMSM based on the compared health parameters (S60).

2. The method according to claim 1, comprising: - Before the first deceleration test, determining the steady-state temperature of the permanent magnets in the PMSM (S1).

3. The method according to claim 2, comprising: - measuring the temperature inside the PMSM and the temperature outside the PMSM (S3); - comparing the measured temperatures inside and outside the PMSM by means of the compared temperature parameters (S5); - determining a steady-state temperature of the PMSM and a steady-state temperature of the permanent magnets in the PMSM in response to determining that the compared temperature parameter is below a threshold temperature difference (S7).

4. The method according to claim 3, wherein: The temperature inside the PMSM is the temperature in the stator winding of the PMSM, and the temperature outside the PMSM is the temperature in the drive shaft or the gearbox.

5. The method according to any one of claims 1 to 4, wherein the PMSM is operated by a current controller, and wherein the first deceleration test and / or the second deceleration test is performed by accelerating the PMSM to a base speed, whereby a current reference of the current controller is set to zero. 6 . The method of claim 5 , wherein the PM flux is determined by a ratio of a voltage reference of the current controller to an electrical angular velocity.

7. The method according to any one of claims 1 to 4, wherein the no-load power loss is determined by multiplying the loss torque of the PMSM by the mechanical angular velocity. 8 . The method of claim 7 , wherein the loss torque is estimated by multiplying the magnitude of the acceleration by the moment of inertia of the rotating shaft of the PMSM.

9. The method of claim 8, wherein the magnitude of the acceleration depends on the PM flux, and wherein correlating the PM flux with the no-load power loss in the health parameter of the PMSM comprises making the PM flux and the no-load power loss dependent on each other.

10. The method according to any one of claims 1 to 4, wherein the health parameter is a multi-valued parameter, and the known health parameter of the reference data is a corresponding multi-valued parameter.

11. The method according to any one of claims 1 to 4, comprising: - determining whether the compared health parameter meets a preset standard, and if the health parameter meets the preset standard, classifying the performance of the PMSM, wherein the classification is associated with a reduced performance of the PMSM (S70).

12. The method according to any one of claims 1 to 4, wherein the PMSM is installed in a vehicle, and the method is performed offline when the vehicle is at rest.

13. The method according to any one of claims 1 to 4, comprising: - performing a stationary characterization of the PMSM to estimate the winding flux (Ψd, Ψq) as a function of current (S90); - adding the PM flux to the estimated turn linkage flux (S100) to provide a flux characteristic of the PMSM, the flux characteristic being included in the classification of the performance of the PMSM; - Adapting control parameters of the PMSM based on the flux characteristics (S110).

14. The method of claim 13, wherein the classification of the performance of the PMSM is used to adapt the control parameters of the PMSM.

15. A control device (3, 103) for controlling the operation of an electric traction machine being a permanent magnet synchronous motor (PMSM) (20, 120), the PMSM being coupled to a drive shaft (140) and powered by a battery (30, 160) via an inverter (170), the control device being configured to: - decoupling the PMSM from the drive shaft; - performing a first deceleration test to measure the flux linkage of the permanent magnets in the PMSM, i.e., the PM flux; - performing a second deceleration test to measure the no-load power loss of the PMSM, in which the inverter is disconnected; - correlating the PM flux and the no-load power loss in a health parameter of the PMSM and comparing the health parameter with reference data of known health parameters of a population of PMSMs; - Classifying the performance of the PMSM based on the compared health parameters.

16. An arrangement (10, 110) comprising: an electric traction machine as a permanent magnet synchronous motor (PMSM) (20, 120) connectable to a drive shaft (140) of a vehicle and configured to be powered by a battery (30, 160) via an inverter (170); and - A control device (3, 103) according to claim 15.

17. A vehicle (1) comprising an arrangement according to claim 16.

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