Method for estimating the electromagnetic torque of a synchronous electrical machine - Patents.com

Abstract

The device for estimating the electromagnetic torque of a three-phase synchronous electric machine including permanent magnets comprises: a first flux estimator (10) having two integrators (103) of electromotive force for estimating respective components (I) of flux in a stationary two-phase reference system associated with a stator; an estimator (20) for estimating torque (II) from the respective estimated flux components (I); a second flux estimator (40) using currents indicated in a rotating two-phase reference system associated with a rotor, the second flux estimator having an observer for determining variables characterizing the magnetic uncertainty of the machine with a view to correcting the flux estimates of the second estimator; and a detection device (30) for generating a signal (RES) for resetting the initial flux conditions of the two integrators based on the flux estimates delivered by the second estimator when a discrepancy between the estimated torque and a setpoint torque is greater than a predetermined threshold.

Description

[Technical field]

[0001] The present invention relates to a method for estimating the electromagnetic torque of a three-phase synchronous electric machine, in particular a permanent magnet three-phase synchronous electric machine (PMSM). [Background technology]

[0002] The invention is advantageously applied in the field of hybrid-electric and electric vehicles, in which machines of this type are widely used as traction motors, particularly in the electric driving mode of the vehicle, due to their robustness, simplicity and low maintenance costs.

[0003] In vehicles with electric running, it is necessary, especially for safety and / or controllability reasons, to know the true value of the motor torque delivered by the electric machine. Typically, the mechanical drive torque of the machine is obtained from a torque meter that measures the torque on the shaft. However, for many reasons, such as cost, reliability and size, it is desirable to remove the torque meter from the drive system and to replace it with a torque estimator.

[0004] The torque estimator is configured to estimate the true value of the torque delivered by the electric machine using certain available variables such as voltage, current and rotor position.

[0005] In a conventional manner, an electric machine may be represented using two two-phase models using Clarke transformations based on a stationary two-phase reference frame associated with the stator and Park transformations based on a rotating two-phase reference frame associated with the rotor. The quantities thus transformed in the reference frames associated with the stator and rotor correspond to the two axes in the stationary two-phase reference frame and the two axes in the rotating two-phase reference frame, respectively, and are denoted using the subscripts α, β on the one hand and d, q on the other hand.

[0006] Due to the strong relationship between the machine flux and the delivered torque, the machine torque can be observed through an estimate of the machine's flux. Several techniques are currently known for estimating the flux of permanent magnet three-phase synchronous electric machines based on two-phase currents and voltages. These techniques are classified into two categories, based on voltage and current models, respectively.

[0007] For the voltage model based flux estimation technique, the electromotive force is calculated using the voltages and currents measured in a reference frame associated with the stator. The stator flux is then obtained by calculating the integral of the electromotive force.

[0008] However, this estimation method implies precise knowledge of the initial magnetic conditions (permanent magnet flux and stator inductance), which may not always be realistic. Hence, due to this uncertainty, there may be a resulting offset in the flux amplitude estimate compared to the true flux of the machine. This offset in the flux estimate using the voltage-flux model then gives rise to an oscillatory term in the estimated torque.

[0009] Moreover, demagnetization and magnetic saturation problems that are likely to occur during machine operation also give rise to oscillatory terms in the torque that is estimated using the voltage-flux model of the machine.

[0010] Another source of deviation in such estimated torque is nonlinearities in the inverter through which the machine is powered and / or measurement uncertainties which cause an offset in the calculated electromotive force value and hence in the estimated flux value.

[0011] Another problem to be solved is ensuring observability at low or zero speeds.

[0012] The problem of observability at low speeds arises when certain filters are added to overcome the problems mentioned above (unknown magnetic conditions and electromotive force offsets).

[0013] The prior art discloses the following documents regarding flux estimation based on a voltage model:

[0014] US Patent No. 9985564B2 describes a method for estimating the stator flux of a permanent magnet three-phase synchronous electric machine based on a voltage model in a two-phase reference frame α, β. Instead of using a pure integrator to integrate the electromotive force, the patent proposes using an electromotive force low-pass filter and then adding a compensator to correct the gain and phase changes caused by the filter.

[0015] CN103346726A also proposes estimating the flux of a permanent magnet three-phase synchronous electric machine based on electromotive force. The patent proposes to use a second-order filter instead of a pure integrator. The patent also proposes to estimate the inductance of the q-axis of a two-phase reference frame to improve the estimation using a voltage model.

[0016] US Patent No. 7,098,623 B2 describes a method for estimating rotor position by estimating stator flux using a voltage model in a two-phase reference frame d,q. The patent proposes adaptively observing the flux based on injection of a low speed, high frequency signal.

[0017] EP1513250 describes a method for combining a flux estimation based on a voltage model and the injection of a high frequency signal for position estimation.

[0018] For methods based on current models, the flux is preferably estimated using the current in a reference frame associated with the rotor. These methods based on current models make it possible to overcome the limitations mentioned above linked to methods based on voltage models, since they do not involve the use of an open-loop integrator. However, problems to be solved for these methods relate to inductance variations due to magnetic saturation, uncertainties in the permanent magnet flux, and the need for a position sensor.

[0019] The following documents are known from the prior art regarding flux estimation based on current models:

[0020] US Patent No. 7,774,148 B2 describes a method for estimating the torque of a permanent magnet three-phase synchronous electric machine based on flux estimates using a current model: the d-axis and q-axis fluxes are represented by two nonlinear current functions.

[0021] CN103872951A describes a torque estimator for a permanent magnet three-phase synchronous electric machine based on flux estimation using a sliding mode observer applied to a voltage model combined with a current model.

[0022] JP 2004-166408 A describes an adaptive flux estimator for permanent magnet three-phase synchronous electric machines, based on a voltage model with correction terms based on a current model. Summary of the Invention

[0023] In this context, the aim of the present invention is to propose a method for estimating the torque of an electric machine, in particular a permanent magnet synchronous electric machine for electric or hybrid vehicles, said method being robust with respect to the limitations mentioned above.

[0024] To this end, the invention relates to a method for estimating the electromagnetic torque of a permanent magnet three-phase synchronous electric machine for an electric or hybrid vehicle, said method comprising the steps of: - measuring currents and voltages for a number of phases of the stator of the machine in a stationary three-phase reference system associated with the stator; - determining currents and voltages in a stationary two-phase reference frame associated with said stator as a function of said current and voltage measurements in said three-phase reference frame; - calculating a first estimate of the machine flux by calculating an integral of the electromotive force, the electromotive force being calculated based on the voltages and currents presented in the stationary two-phase reference frame associated with the stator; - estimating the electromagnetic torque based on the flux estimated by the first estimate. In a method comprising the steps of: - determining currents and voltages in a rotating two-phase reference frame associated with the rotor as a function of the currents and voltages exhibited in the stationary two-phase reference frame and the position of the rotor relative to the stator; - calculating in parallel a second estimate of the flux of the machine using the currents represented in the rotating two-phase reference frame associated with the rotor, the second flux estimate being corrected by introducing a variable characterizing a magnetic uncertainty of the machine, the variable being determined by an observer based on the stator currents and voltages represented in the rotating two-phase reference frame associated with the rotor; - comparing said estimated torque with a setpoint torque; - resetting an initial condition of the flux relative to the first estimate based on the flux estimated by the second estimate when a difference between the estimated torque and the setpoint torque exceeds a predetermined threshold. The present invention is characterized by comprising:

[0025] Advantageously, the method may comprise the step of stopping the calculation of the second flux estimate when the difference between the estimated torque and the setpoint torque is less than or equal to the threshold value.

[0026] Advantageously, the method may include the step of determining the proportion of time that said calculation of said second flux estimate is activated relative to an operating time of the machine.

[0027] Advantageously, the method may include the step of compensating for an offset in the calculated electromotive force before the calculated electromotive force is used in the first flux estimation.

[0028] Advantageously, said second estimate of the flux of said machine comprises: - determining a flux-current model of the machine, taking into account a saturation function of the machine so as to take into account in said model the variations in the magnetic parameters of the machine caused by magnetic saturation and demagnetization of the machine; - introducing into said model said variables characterizing the magnetic uncertainty of said machine inherent to the variations of said magnetic parameters of said machine; - a step, executed by the observer, of estimating the variables of the model; - calculating the second flux estimate based on the estimated variables; Includes.

[0029] Advantageously, the magnetic parameters under consideration are the linear inductance of the stator, respectively of each axis of the rotating two-phase reference system associated with the rotor, and the magnetic flux generated by the permanent magnets of the rotor of the machine.

[0030] Advantageously, the saturation function represents magnetic and cross saturation in the machine.

[0031] Advantageously, the method includes the step of adjusting the observer using a Kalman algorithm.

[0032] The invention also relates to a device for estimating the electromagnetic torque of a permanent magnet three-phase synchronous electric machine for an electric or hybrid vehicle, said device being configured to receive currents and voltages measured for the phases of a stator of said machine in a stationary three-phase reference system associated with said stator, which are transformed into a stationary two-phase reference system associated with said stator, said device comprising: a first flux estimator for estimating the flux of the machine in the stationary two-phase reference system associated with the stator, the first flux estimator comprising two electromotive force integrators for estimating respective components of the flux along two direct and quadrature axes of the stationary two-phase reference system associated with the stator, the electromotive forces being calculated based on currents and voltages applied to each axis of the stationary two-phase reference system associated with the stator; a torque estimation device configured to estimate the torque of the machine based on the respective components of the flux estimated in the two axes of the stationary two-phase reference system associated with the stator; 1. A device comprising: a second flux estimator configured to receive the currents and voltages indicated in the stationary two-phase reference frame, transformed into a rotating two-phase reference frame associated with the rotor as a function of the position of the rotor relative to the stator, the second estimator configured to estimate the flux using the currents indicated in the rotating two-phase reference frame associated with the rotor, the second estimator configured to determine variables characterizing a magnetic uncertainty of the machine, the second estimator comprising an observer based on the stator currents and voltages indicated in the rotating two-phase reference frame associated with the rotor, the variables being used to correct the flux estimates of the second estimator; a detection device configured to compare the torque estimated by the torque estimation device with a setpoint torque and to generate a signal capable of commanding resetting of the initial conditions of the flux of the two integrators of the first flux estimation device when a difference between the estimated torque and the setpoint torque is greater than a predetermined threshold, the initial conditions being reset based on the flux estimates provided by the second flux estimation device; The present invention is characterized by comprising:

[0033] Advantageously, the signal may stop the calculation of the second flux estimate by the second flux estimator when the difference between the estimated torque and the set point torque is less than or equal to the threshold value.

[0034] Other characteristics and advantages of the invention will emerge more clearly on reading the following description, given by way of illustrative and non-limiting example, with reference to the single following figure. [Brief description of the drawings]

[0035] [Figure 1] FIG. 2 is a functional block diagram of a device for implementing the electromagnetic torque estimation method according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Of more particular interest in the present context is therefore the case of permanent magnet three-phase synchronous electric machines used in hybrid and electric vehicle applications.

[0037] In a first step, currents and voltages are measured for each of the three phases of the stator of a permanent magnet three-phase synchronous machine.

[0038] Next, the Park transformation gives the direct voltage component v d and the quadrature voltage component v q Along with the direct current component i d and quadrature current component i q is applied to the quantities measured for the three phases to obtain

[0039] It is thus possible to transform the three currents and the three sinusoidal voltages of the stator for the three phases of a three-phase system into a space in which the three sinusoidal current and voltage signals are represented in the form of two constant current and voltage signals, respectively the component of the direct axis and the component of the quadrature axis q. For this purpose, the Park reference frame is based on a reference frame related to the rotor.

[0040] The torque estimator that will be described in this context is based on a flux estimation of the machine that is performed on the basis of an improved voltage-flux model of the machine.

[0041] The estimated electromagnetic torque of the machine, shown in TIFF0007606524000001.tif11170, is given by the following equation (1): TIFF0007606524000002.tif19170 Here, -i α and i β are the direct and quadrature components, respectively, of the stator current in the Clarke domain, with α relating to the direct axis and β relating to the quadrature axis of the Clarke domain, - λ α and λ β are the direct and quadrature components, respectively, of the total flux seen by the stator in the Clarke domain, - p is the number of pole pairs of the machine.

[0042] The total flux seen by the stator of a permanent magnet synchronous electric machine may be estimated by calculating the integral of the electromotive forces using the following set of equations (2): TIFF0007606524000003.tif11170TIFF0007606524000004.tif12170Here, R S is the resistance of the stator, and ν α and ν β represent the direct and quadrature components, respectively, of the stator voltage in the Clarke domain, TIFF0007606524000005.tif11170 shows the initial conditions of the line flux with direct and quadrature components in the Clarke domain.

[0043] As will be explained in more detail below, to overcome the problems of estimating the flux using a voltage model of the machine, the present invention provides an initial condition for the integrator We propose to improve the above model by combining a modified current model and a voltage model to reset TIFF0007606524000006.tif12170.

[0044] More specifically, these initial flux conditions are determined using a current model and appropriate observers configured to estimate the magnetic uncertainties of the model caused by magnetic saturation and demagnetization.

[0045] In fact, the relationship between the flux and the stator phase current is linear for low current levels. However, for high currents, this linearity is no longer maintained, which generally leads to saturated operation. In addition, high temperature operation of the machine causes fluctuations (degaussing) of the permanent magnet flux. The inductance and flux of the permanent magnets of the machine thus vary significantly in a predictable manner due to the magnetic saturation and deegaussing of the machine. Hence, in order to improve the model's behavior, it is proposed to adopt a modified flux-current model that takes these fluctuations into account.

[0046] For this purpose, consideration will be given to the unknown magnetic conditions of the machine in the current model. The unknown magnetic conditions under consideration are the linear inductance of the stator, the flux of the permanent magnets, and the saturation function of the machine, which represents the magnetic saturation and cross saturation in the machine.

[0047] Consideration of the above unknown magnetic conditions of the machine in the model results in the following system of equations in Park space: TIFF0007606524000007.tif53170 Here, TIFF0007606524000008.tif12170 are the components of the stator flux generated on the direct d-axis and quadrature q-axis of the machine park plane, respectively, and ν d and ν q are the voltages applied to the two direct d-axes and quadrature q-axes of the machine park plane, respectively, and i d and i qare the currents flowing in the machine on the two direct d-axes and quadrature q-axes of the machine's Park plane, respectively, and R S is the equivalent resistance of the machine's stator, and L d0 and L q0 are the linear inductances of the stator on the direct d-axis and quadrature q-axis of the machine park plane, respectively, and φ f is the magnetic flux generated by the rotor permanent magnets, and ω e is the angular velocity of the rotor.

[0048] f sat(1,2) is a function that represents magnetic saturation and cross saturation in the machine.

[0049] and: TIFF0007606524000009.tif50170Here, L d0m and L q0m are the exact values ​​of the linear coefficients between the flux and the stator current on the direct d-axis and quadrature q-axis of the machine park plane, respectively, and φ fm is the true value of the magnetic flux generated by the rotor permanent magnets, and f sat(1,2)m is the true saturation function of each machine. Therefore, the parameter TIFF0007606524000010.tif12170 represents the difference between the true and reference values ​​of the above parameters in the model proposed by equations (3) and (4).

[0050] Two variables g1 and g2 are then introduced into the current model, which correspond to the unknown magnetic conditions. For this purpose, the stator current i d and i q Consider first equation (3) which is replaced in equation (4) to give: TIFF0007606524000011.tif27170 where: TIFF0007606524000012.tif27170

[0051] The variables g1 and g2 therefore group together all the magnetic uncertainties of the machine, resulting from the variations in inductance due to magnetic saturation and the uncertainties of the permanent magnet flux. In other words, the variables g1 and g2 that will be observed make it possible to represent the magnetic behavior of the machine that changes due to magnetic saturation. The introduction of the parametric uncertainties described by the variables g1 and g2 into the current model makes it possible to reflect the fact that the values ​​of the magnetic parameters of the system (inductance and permanent magnet flux) can differ from the model due to saturation and demagnetization of the machine. Observing these variables will make it possible to correct these uncertainties, as will be explained below.

[0052] The above variables presented in the model will therefore be estimated using an appropriate observer. Hence, the basis is the above described flux-current model of the machine, which takes into account the variations caused by the magnetic saturation and demagnetization of the machine in the magnetic parameters of the machine, which are the inductance and the permanent magnet flux, as well as the observer theory, which includes the concept of observability and a state observer. Thus, when the state of the system cannot be measured, the observer is configured and allows to reproduce this state based on a model of the system and measurements of other states. State is understood to mean a set of physical values ​​that define the observed system. A Kalman observer will be used here to observe the magnetic uncertainty of the machine as characterized by the variables g1 and g2.

[0053] Hence, the variables g1 and g2 are considered to be two new state variables. In this model, g1 and g2 are assumed to be piecewise constant functions, i.e. functions whose values ​​are constant over intervals. The system of equations modeling the electric machine may be reformulated in the general form for nonlinear systems: TIFF0007606524000013.tif16170y=h(x) where: TIFF0007606524000014.tif50170

[0054] For a system modeled in this way, the observer may be formulated by the following equation: TIFF0007606524000015.tif42170 Here, TIFF0007606524000016.tif9170 is the vector of estimated states corresponding to the state vector: TIFF0007606524000017.tif27170And K is the gain of the observation instrument.

[0055] The choice of a gain K that multiplies the error term makes it possible to adjust the observer. This gain is calculated by the Kalman algorithm.

[0056] The rotor electrical angular speed is considered as an input for a system of matrices A. This allows the state to be observed. Hence, the use consists of a time-varying observer gain K such that: K=P -1 C T R -1 (9) Here, the dynamic range of the variable P is defined as: TIFF0007606524000018.tif22170

[0057] The matrices Q and R are positive definite symmetric weighting matrices.

[0058] Thus, after estimating the two variables g1 and g2 using the observation device, the total stator flux may be estimated based on equations (4) and (7) defined above: TIFF0007606524000019.tif27170

[0059] It can be seen that the flux-voltage model of the machine is given by the set of equations (2) explained above, on the basis of which the flux of the machine can be estimated by calculating the integral of the electromotive force. Hence, the estimation of the stator flux by the voltage model is, according to the invention, based on the use of a resettable integrator, making it possible to estimate the flux based on the modified current model by applying the set of equations (11), as explained above, insofar as the initial conditions of the flux for the integrator are determined by an independent observation device.

[0060] The use thus comprises a first estimator based on a voltage model implementing two pure integrators to estimate the flux in two axes α and β corresponding to the two axes of the stationary two-phase reference system, and in parallel comprises another flux estimator based on a current model in a rotating two-phase reference system dq modified by means of an observer to estimate initial flux conditions for the two integrators.

[0061] Then, based on the flux estimation performed using the voltage model thus improved by the use of another flux estimator based on a current model, the electromagnetic torque generated by the permanent magnet synchronous electric machine may be calculated by applying equation (1).

[0062] In order to minimize the calculation times in real-time processing, it is proposed to stop the processing linked to the observer when it is not absolutely necessary to initialize the integrator. A detection device is thus proposed for determining the time of initialization. This detection device comprises: The torque estimated by the voltage model shown in FIG. TIFF0007606524000020.tif12170 corresponds to the torque to be supplied by the electric machine of the vehicle and is provided by the control system of the vehicle based on the accelerator pedal depression by the driver. * eThe setpoint torque is compared with the estimated torque, denoted by . If the absolute value of the error between the setpoint torque and the estimated torque exceeds a predefined threshold ε, the observer will be activated and the two integrators of the flux estimator based on the voltage model will be reset based on the initial flux conditions determined by the flux-current model modified with the observer. Therefore, a Boolean operator for triggering the resetting of the integrators is introduced into the voltage model and is defined as follows: TIFF0007606524000021.tif34170

[0063] The observer is activated and deactivated when the operator "RES" changes to "1" and "0", respectively.

[0064] It can be meaningful to ascertain the proportion of time that the observation device is activated compared to the total operating time of the machine to drive the vehicle. Therefore, a new monitoring variable is introduced, which is: TIFF0007606524000022.tif24170Here, Σt i is the total time that the observation device is activated, and t tot is the total operating time. The monitored variable OT can vary from 0 to 100% as a function of unknown initial flux conditions at start-up, magnet quality, motor saturation conditions, setpoint torque variations, etc.

[0065] Measurement uncertainties and / or nonlinearities of the inverters to which the machine is powered may result in an offset in the calculated electromotive force. Therefore, in order to compensate for said offset so as to avoid deviations of the estimated flux values ​​over time, it is performed to calculate the average value of the estimated flux values ​​as follows: TIFF0007606524000023.tif23170 where T is the period of current.

[0066] e αβ-offsetrepresents the offset of the calculated electromotive force. This value should be subtracted from the electromotive force calculated online based on the flux-voltage model before it is used in the integrator of the flux estimator.

[0067] FIG. 1 illustrates a block diagram of a method for estimating the electromagnetic torque of a machine.

[0068] First, current and voltage measurements are collected for each of the three phases of the stator of a permanent magnet three-phase synchronous machine.

[0069] The projections of the measured stator electrical quantities for the three phases onto the two fixed axes (α,β) of the fixed two-phase, direct and quadrature, reference system are obtained by applying the Clarke transformation. Thus, the current and voltage components i applied to the two direct and quadrature axes, respectively, of the Clarke domain are αβ and V αβ is considered at the input of the device of FIG. 1 and fed to a first flux estimator 10 based on a voltage model.

[0070] The first flux estimation device 10 receives at its input the components i αβ and V αβ and stator resistance R S Based on the electromotive force e on each of the two axes of the Clarke domain αβ First, the direct and quadrature components of

[0071] Therefore, the first flux estimator 10 calculates the value of the stator resistance R for each direct and quadrature component of the Clarke domain. S and the current i for the axis under consideration αβand supplies its output to a respective adder 102. For each component under consideration, the corresponding adder 102 then subtracts the output of the multiplier 101 from the adder input at which the corresponding stator voltage component is received, and at its output produces an electromotive force e αβ to a respective integrator 103. For each component under consideration, the corresponding integrator 103 calculates the integral of the electromotive force, respectively the direct and quadrature components of the total flux seen by the stator in the Clarke domain. Supply TIFF0007606524000024.tif10170 at the output section.

[0072] These direct and quadrature components of the total flux seen by the stator in the Clarke domain, respectively TIFF0007606524000025.tif10170 is calculated by applying the above-mentioned formula (1) to the electromagnetic torque supplied by the machine. The torque is then fed to the torque estimator 20 which will calculate the torque vector TIFF0007606524000026.tif12170.

[0073] As explained above, the torque estimator 20 estimates the torque based on the voltage model. Set the torque value T * e the output of the torque estimator to a detection device 30 configured to compare Thus, the detection device 30 receives the output provided by the torque estimation device 20. From TIFF0007606524000029.tif12170, the above set torque value T * eand supplies the output of the detection device as an absolute value to a comparator 32. Said comparator compares the absolute value of the error between the estimated torque and the setpoint torque with a predetermined threshold value ε and supplies at its output a Boolean operator RES which commands the resetting of the two integrators 103 of the first flux estimator 10 when the difference in absolute value between the estimated torque and the setpoint torque changes to the value “1”, meaning that the difference in absolute value between the estimated torque and the setpoint torque is greater than the predetermined threshold value.

[0074] The implementation of this reset of the two integrators 103 of the first flux estimator 10 is based, according to the invention, on the activation of a second flux estimator 40, based on a current model in the reference frame (d, q) corrected by means of the observer to correct the estimated flux taking into account the magnetic uncertainties of the model of the machine, as explained above. Hence, the signal RES is used to activate and preferably deactivate this second flux estimator 40, when said signal changes to "1" and "0", respectively.

[0075] The Park conversion circuit 41 converts the rotor position θ e The Clarke transformation of the measured stator electrical quantities is therefore carried out as a function of the components i of the reference system (α, β) αβ and V αβ into continuous components along the two direct d-axes and the quadrature q-axis of the machine park plane.

[0076] Therefore, the current and voltage components i applied to the two direct d-axes and quadrature q-axes of the machine park plane, respectively, αβ and V αβ is fed at the input of a second flux estimator 40 which is based on a current model and is corrected using an observer.

[0077] Rotor speed ω e is also fed at the input of this second flux estimator 40.

[0078] After estimating the two variables g1 and g2 using the observation device as explained above, the second flux estimation device 40 at its output calculates the estimated direct d and quadrature q components, respectively, of the total flux in the Park plane by applying the set of equations (11) explained above. Supply TIFF0007606524000030.tif11170.

[0079] These components are the rotor position θ e The inverse Park transformation 42 performs an alternation from the reference frame (d,q) to the reference frame (α,β) as a function of . Hence, the inverse Park transformation 42 is performed by the components of the total flux in the two-phase reference frame α,β estimated on the basis of the flux-current model of the machine associated with the observation device in order to take into account the magnetic uncertainty of the flux-current model of the machine. Supply TIFF0007606524000031.tif10170 at the output section.

[0080] Therefore, when the second flux estimator 40 based on the flux-current model is activated as a function of the signal RES for resetting the two integrators 103 of the first estimator 10 based on the flux-voltage model, these components are reset according to the initial conditions of the integrators This is supplied to two integrators 103 to reset TIFF0007606524000032.tif10170.

[0081] The device of FIG. 1 also comprises a monitoring circuit 50 intended to measure, by means of an observer, through the variable OT explained above, the activation period of the second estimator 40.

[0082] Finally, the device of FIG. 1 also operates with a value of e determined in accordance with the principles set forth above. αβ-offsetAt its output, a circuit 60 is also described for estimating the offset of the electromotive force. This offset value is provided to the summer 102 for subtraction from the calculated electromotive force at its output.

[0083] Thus, the torque of the machine can be estimated in an accurate and robust manner even without knowledge of the initial magnetic conditions and taking into account all the variations in the magnetic parameters during operation of the machine.

Claims

1. 1. A method for estimating electromagnetic torque of a permanent magnet three-phase synchronous electric machine for an electric or hybrid vehicle, comprising: measuring currents and voltages for a number of phases of the stator of the machine in a stationary three-phase reference system associated with the stator; the currents and voltages (i αβ , v αβ ) - the flux of the machine by calculating the integral of the electromotive force wherein the electromotive force is calculated based on the voltages and currents represented in the stationary two-phase reference frame associated with the stator; - said electromagnetic torque based on said flux estimated by said first estimate and estimating In a method comprising the steps of: - the currents and voltages (i αβ , v αβ ) and the position of the rotor relative to the stator (θ ｅ ) as a function of the current and voltage (i ｄｑ , v ｄｑ ) - the flux of the machine using the currents expressed in the rotating two-phase reference frame associated with the rotor wherein said second estimate of flux is corrected by introducing variables characterizing the magnetic uncertainty of the machine, said variables being the stator currents and voltages (i ｄｑ , v ｄｑ determining a second estimate, determined by the observer based on the a torque estimated on the basis of said flux estimated by said first estimate and the set torque (T ＊ ｅ ) and resetting an initial condition of the flux estimated by the second flux estimate in relation to the first flux estimate when the difference between the torque estimated by the first flux estimate and the setpoint torque exceeds a predetermined threshold (ε); A method comprising:

2. 2. The method of claim 1, further comprising the step of stopping the calculation of the second flux estimate when the difference between the torque estimated based on the flux estimated by the first estimate and the setpoint torque is less than or equal to the threshold.

3. 3. The method of claim 2, wherein said calculating said second flux estimate comprises determining a ratio of start-up time to operating time of said machine.

4. 4. The method according to claim 1, further comprising the step of compensating for an offset in the calculated electromotive force before the calculated electromotive force is used in said first estimation of flux.

5. The second estimate of the flux of the machine may comprise: determining a flux-current model of the machine, taking into account in said model a saturation function of the machine in order to take into account the variations in the magnetic parameters of the machine caused by magnetic saturation and demagnetization of the machine; introducing into said model said variables characterizing the magnetic uncertainty of said machine, specific to the variations of said magnetic parameters of said machine; a step of estimating the variables of the model, performed by the observer; - calculating said second flux estimate based on the estimated variables; 5. The method according to claim 1 , further comprising:

6. 6. The method according to claim 5, characterized in that the magnetic parameters taken into account are the linear inductance of the stator of each axis, respectively, of the rotating two-phase reference system associated with the rotor, and the magnetic flux generated by the permanent magnets of the rotor of the machine.

7. 7. A method according to claim 5 or 6, characterized in that the saturation function represents magnetic saturation and cross saturation in the machine.

8. 8. A method according to any one of claims 1 to 7, characterized in that it includes the step of adjusting the observer using a Kalman algorithm.

9. A device for estimating electromagnetic torque of a permanent magnet three-phase synchronous electric machine for an electric or hybrid vehicle, the device being configured to receive currents and voltages measured for a number of phases of a stator of the machine in a stationary three-phase reference system associated with a stator, the currents and voltages being transformed into a stationary two-phase reference system associated with the stator, the device comprising: A first flux estimation device (10) for estimating a flux of the machine in the stationary two-phase reference system associated with the stator, the first flux estimation device (10) estimating respective components of the flux along two direct and quadrature axes of the stationary two-phase reference system associated with the stator. The electromotive force is calculated by estimating the current and voltage (i αβ , v αβ a first flux estimator (10) calculated based on the respective components of the flux estimated in two axes of the stationary two-phase reference system associated with the stator; Based on the torque of the machine A torque estimation device (20) configured to estimate In a device comprising: The position of the rotor relative to the stator (θ ｅ ) into a rotating two-phase reference system associated with the rotor, the currents and voltages (i αβ , v αβ ), wherein the second flux estimator (40) is configured to receive the current (i ｄｑ ) to estimate the flux, and the second flux estimator (40) is configured to determine variables characterizing the magnetic uncertainty of the machine, and to estimate the stator currents and voltages (i ｄｑ , v ｄｑ a second flux estimator (40) comprising an observer based on said first flux estimator (40), said variables being used to correct flux estimates of said second flux estimator (40); the respective components of the flux estimated in the two axes of the stationary two-phase reference system associated with the stator; The torque estimated by the torque estimation device (20) based on The set torque and a detection device (30) configured to generate a signal (RES) capable of commanding a reset of initial conditions of the flux of the two electromotive force integrators (103) of the first flux estimator (10) when a difference between the estimated torque and the setpoint torque is greater than a predetermined threshold (ε), the initial conditions being reset based on the flux estimate provided by the second flux estimator (40); A device comprising:

10. 10. The device according to claim 9, characterized in that the signal (RES) is capable of stopping the calculation of the second flux estimate by the second flux estimator (40) when the difference between the estimated torque and the setpoint torque is less than or equal to the threshold value.

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