Method and device for controlling a motor using a direct flux vector control module and a constant current angular trajectory module

Abstract

The present invention relates to a device and method for controlling a motor using a DFVC module and a CCAL module, the invention relates to a device and method for determining a torque reference, the CCAL module determining a flux reference and a current reference from the torque reference and a predetermined angle, providing the flux reference and the current reference to a DFVC module to obtain a reference voltage to be provided to the motor, injecting a high frequency signal into the reference voltage, determining an estimate of the direction of the motor flux from the motor current vector, determining an estimate of the flux and an estimate of the current flowing perpendicular to the estimated direction of the flux from the estimate of the direction of the flux, and providing the estimate of the flux and an estimate of the current flowing perpendicular to the estimated direction of the flux to the DFVC module.

Description

[Technical field]

[0001] The present invention relates generally to methods and devices for controlling a three-phase motor. [Background technology]

[0002] Electric machines are widely used in either factory automation or transportation industries. Many control techniques for machines such as Permanent Magnet Synchronous Machines (PMSM), Synchronous Reluctance Machines (SyncRM), Wound Rotor Synchronous Machines (WRSM) often use rotary encoders to obtain the machine speed and position feedback.

[0003] The demand for low-cost, robust motor drives has increased the development of sensorless controls: without those sensors, mechanical drives are cheaper and more robust to dusty and harsh environments.

[0004] Many techniques for sensorless control have been proposed. These techniques are based on estimating the machine position and speed, but one aspect of sensorless controllers that is often neglected is the strategy of choosing the current reference of the FOC (Field-Oriented Control) controller from a given desired torque reference. MTPA (Maximum-Torque-Per-Ampere) operation uses the minimized current level that can produce a given torque, thus minimizing the level-current induced losses (inverter losses and motor losses) in the motor drive.

[0005] In a CVC (Current Vector Control) controller, the reference quantity is the coordinate of the current vector in the rotor (dq) axis framework. The MTPA condition is satisfied only for a specific direction of the current vector in that framework. The ideal direction depends on the machine parameters, which vary as a function of the current coordinate in both the d-axis and the q-axis.

[0006] To reach the MTPA condition, both the inductance level and the rotor position must be estimated. To address this issue, some machine controllers are equipped with a self-commissioning routine that obtains and stores a lookup table (LUT) of inductance versus current. The drawbacks of this methodology relate to the time required to find such an inductance before first use of the machine being driven, the memory and accuracy required, since it is difficult to obtain a valid inductance table for the full load condition in the absence of a pre-provisioned test load.

[0007] In DFVC (Direct Flux Vector Control), the reference quantities are the flux norm and one current component. This technique operates in a stator flux framework that does not require rotor position estimation. DFVC operation instead requires the estimation of the flux norm and the current component perpendicular to the flux. To operate DFVC under MTPA conditions at a given torque, it is also required to identify the optimal flux norm. As an example, for high speed, the optimal flux norm is identified, which is reached when the High Frequency (HF) current response of the machine to an HF voltage pattern injected in the direction of the current vector becomes perpendicular to the current vector. Summary of the Invention [Problem to be solved by the invention]

[0008] The main problem with using DFVC is that it relies on a flux estimator. In the absence of a LUT, a typical flux estimator is based on Back Electro Motive Force (BEMF) sensing, which is the product of speed and flux linkage. However, at low and zero speed, it is not possible to properly estimate the flux via BEMF. As a result, sensorless DFVC is prone to stability issues at low speeds in the absence of a LUT. [Means for solving the problem]

[0009] The present invention aims to provide a sensorless control method and device using an effective sensorless DFVC control at low speed without LUT. To this end, the present invention provides a method for controlling a motor using a direct flux vector control module and a constant current angular trajectory module, comprising: determining a torque reference; a constant current angle trajectory module determining a flux reference and a current reference from a torque reference and a predetermined angle; providing a flux reference and a current reference to a direct flux vector control module to obtain a reference voltage provided to the motor; injecting a high frequency signal into a reference voltage; determining an estimate of the motor flux direction from the motor current vector; determining an estimate of the norm of the magnetic flux and an estimate of a current flowing perpendicular to the estimated direction of the magnetic flux from the estimate of the direction of the magnetic flux; providing an estimate of the norm of the magnetic flux and an estimate of the current flowing perpendicular to the estimated direction of the magnetic flux to a direct flux vector control module; The present invention relates to a method comprising the steps of:

[0010] The present invention also provides a device for controlling a motor using a direct flux vector control module and a constant current angular trajectory module, comprising: A means for determining a torque reference; a constant current angle trajectory module for determining a flux reference and a current reference from a torque reference and a given angle; means for providing a flux reference and a current reference directly to a flux vector control module to obtain a reference voltage provided to the motor; means for injecting a high frequency signal into a reference voltage; means for deriving an estimate of the direction of the motor flux from the motor current vector; means for determining an estimate of the norm of the magnetic flux and an estimate of the current perpendicular to the estimated direction of the magnetic flux from an estimate of the direction of the magnetic flux; means for providing an estimate of the norm of the magnetic flux and an estimate of the current flowing perpendicular to the estimated direction of the magnetic flux directly to the flux vector control module; The present invention relates to a device comprising:

[0011] Thus, the flux reference and the current perpendicular to the flux reference are determined at any condition, including low speed conditions. The angle between the estimated current and the estimated flux is stabilized, so that the resulting torque is stable. This stability is maintained at low speeds, even when the quality of the flux estimate is poor.

[0012] The proposed sensorless control is equally effective at low speeds and stationary conditions. Since the scheme works well at low speeds, a similar control structure can be applied at high speeds (e.g., above 200 rpm) as well, using a highly accurate BEMF-based flux estimator with a smooth transition between low and high speed regions (e.g., 200 rpm). The DFVC controller does not require rotor angle estimation, and as a result, the controller structure is not prone to instability due to inaccuracies in the rotor position estimation.

[0013] According to a particular feature, the flux reference is determined using a first function of the motor's nominal parameters multiplied by the square root of the product of the torque divided by the tangent of the reference angle, and the current reference is determined using a second function of the motor's nominal parameters multiplied by the square root of the product torque reference multiplied by the tangent of the reference angle.

[0014] Therefore, the flux and current references used in the DFVC ensure that under any torque condition, the DFVC control is achieved with a fixed angle between the flux and current vectors.

[0015] According to a particular feature, the first function is

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[0016] Therefore, the torque generated by the DFVC controller is a good approximation of the reference torque under nominal conditions. Under other torque conditions, the generated torque may deviate from the reference torque level. However, the level of the generated torque is stable even at low speeds, and the level of the torque reference can be adjusted.

[0017] In the presence of errors in the flux estimate, the DFVC trajectory taken by the DFVC controller does not deviate far from the optimal maximum torque per current (MTPA) condition. Hence, the CCAL controller is stable but also efficient at low speeds.

[0018] According to a particular feature, the magnetic flux reference λ * and current reference i τ * is calculated according to the following formula:

number

[0019] According to a particular feature, the predetermined angle is comprised between 30 degrees and 45 degrees.

[0020] Therefore, the DFVC trajectory does not deviate too far from the MTPA trajectory, and angles outside this range may cause problems such as DFVC controller instability (for larger angles) or undesirable motor losses (for smaller angles).

[0021] According to a particular feature, the predetermined angle is

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[0022] Therefore, the controller trajectory is in better agreement with the MTPA conditions. The predetermined angle can be matched to the nominal salient poles of the machine from the machine nameplate characteristics.

[0023] According to a particular feature, the predetermined angle is determined as a function of the torque stored in a look-up table.

[0024] Therefore, the MTPA conditions can be met with high accuracy away from the nominal conditions, which improves the efficiency of the DFVC controller at low speeds and stationary conditions. As an example, the table can be obtained using an MTPA tracking algorithm available at high speeds.

[0025] According to a particular feature, the predetermined angle is determined from observed current to torque reference ratios at varying levels of the predetermined angle and varying torque reference levels, and the optimum angle is determined as the angle which minimizes the observed current to torque reference ratio for the determined torque reference.

[0026] Therefore, the MTPA conditions can be met with high accuracy away from the nominal conditions, which improves the efficiency of the DFVC controller at low speeds and stationary conditions. The controller can acquire the table at stationary conditions without the need to perform the MTPA acquisition at high rotation speeds.

[0027] According to a particular feature, the estimated flux level is estimated as the current projected on the axis of the estimated flux multiplied by a fixed ratio.

[0028] Therefore, it is very easy to obtain the flux estimate even at low speeds. The linear assumption, although with significant errors, adequately reflects the monotonicity of the dependency between the flux level and the current level. In other words, the estimated flux may be prone to estimation errors in norm and / or direction (e.g. due to saturation and / or salient poles), but the estimation errors are locally stable. DFVC can effectively control the erroneous flux estimate towards the reference flux reference even in the low speed / static operating region where the back EMF due to rotation is hardly detectable.

[0029] According to a particular feature, the fixed ratio is determined from the nameplate characteristics of the motor.

[0030] Thus, the estimated flux is estimated without error at the nominal operating point of the machine. At this point, the proposed control method operates at the MTPA condition, i.e., minimizes the level of current required to reach the desired torque level. At other torque conditions, the control method does not operate far from the true MTPA condition, so that the increase in copper losses is kept small. This sensorless control method operates close to the true MTPA condition at low speeds.

[0031] According to a particular feature, the high frequency injection signal is parallel to the estimated magnetic flux vector, and the angle of the magnetic flux vector that drives the high frequency response of the current vector to be parallel to the current is estimated.

[0032] Thus, the angle of the flux vector is estimated despite the lack of knowledge of the precise inductance state of the machine. The proposed control method also works in the absence of any look-up table. Since the HF flux injection is proportional to the flux, it is easy to detect the change in the current level orthogonal to the current direction and drive this to zero.

[0033] According to a particular feature, the high frequency injection is perpendicular to the estimated magnetic flux vector, and an angle of the magnetic flux vector is estimated which drives the high frequency response of the current vector to be perpendicular to the current vector.

[0034] Therefore, the angle of the flux vector is estimated despite having no knowledge of the precise inductance state of the machine. The proposed control method also works in the absence of any look-up table. Since the HF flux injection is perpendicular to the magnetic flux, the iron losses due to HF injection are minimal.

[0035] The characteristics of the invention will emerge more clearly from a reading of the following description of an exemplary embodiment, the said description being produced with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0036] [Figure 1] FIG. 1 illustrates a first example of a direct flux vector controller for a motor using a Constant Current Angle Locus (CCAL) in accordance with the present invention. [Diagram 2] FIG. 2 illustrates an example block diagram of a high frequency injection module in accordance with the present invention. [Diagram 3] FIG. 2 illustrates an example block diagram of a magnetic flux estimation module in accordance with the present invention. [Figure 4] FIG. 2 illustrates an example block diagram of a flux level and current perpendicular to the estimated direction of flux estimation module according to the present invention. [Diagram 5] FIG. 2 is a block diagram of a direct flux vector control module according to the present invention; [Figure 6] FIG. 2 illustrates an example of a torque estimation module in accordance with the present invention. [Figure 7] FIG. 1 depicts a motor framework for use with the present invention. [Figure 8] Estimated direction of magnetic flux vector

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[0037] FIG. 1 shows a first example of a direct flux vector controller for a motor using a constant current angular trajectory according to the present invention.

[0038] The direct flux vector controller for a motor using constant current angle trajectory shown in FIG. 1 includes a current flux angle determination module 100, a constant current angle trajectory module 101, a direct flux vector control module 102, an HF injection module 103, a framework transformation module 104, an inverter 105a connected to a motor 105b, a current measurement module 107, a flux angle estimation module 108, a flux level and current perpendicular to the estimated direction of flux estimation module 109, and a torque reference determination module 110.

[0039] In the case of linear machines, the MTPA operation is performed in a 45 degree dq framework, i.e. I d =I q Current phase angle at

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[0040] When considering a conventional synchronous reluctance machine with a normal salient pole ratio of 2 to 4, this gives a corresponding flux phase angle of 15 degrees to 25 degrees from the d-axis.

[0041] The current flux angle determination module 100 determines a predetermined angle γ, which is the angle of the current vector in the fτ frame that is equal to the difference between the current phase angle and the flux phase angle. λ Determine the given angle γ λ is set in the range of 30 degrees to 45 degrees.

[0042] In a first variant of the invention, the predetermined angle γ λ teeth,

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[0043] In a preferred embodiment of the present invention, the predetermined angle is preferably set to a value greater than or equal to 100° C. (e.g., 150° F.) in order to maintain a stability margin for the sensorless control as the sensorless control operates away from the low incremental saliency region.

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[0044] In another variant of the invention, the predetermined angle γ λis determined as a function of torque stored in a look-up table. For example, at high speed, the MTPA trajectory can be obtained along with inductance data. From such data, the torque can be adjusted to the optimum predetermined angle γ λ At low speeds, a function can be constructed that relates λ is set from the determined torque level.

[0045] In another variation of the invention, the current to torque reference ratio is determined by the angle γ λ and varying torque levels. The optimum angle is determined as the angle that minimizes the current to torque reference ratio of the torque reference determined by the torque reference determination module 110.

[0046] The constant current angle trajectory module 101 is * and angle γ λ * from the magnetic flux reference level λ * and current reference level i τ * Request.

[0047] The constant current angle trajectory module 101 stores the nominal parameters of the motor and calculates the flux reference level λ as a first function. * The first function calculates the nominal parameters of the motor by multiplying the torque standard by the angle γ λ * multiplied by the square root of dividing by the tangent of

[0048] The constant current angle trajectory module 101 determines the current reference level i as a second function. τ * The second function calculates the product torque reference to the nominal parameters of the motor 105 and the angle γ λ * multiplied by the square root of the tangent of

[0049] In a preferred embodiment of the present invention, the first function is:

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[0050] Torque is generally expressed as follows:

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[0051] At the nominal operating point, ||λ||=λ n and i τ =I n sin(φ n ), and therefore, T n =(3p / 2)λ n I n sin(φ n ). n , λ n , φ n , T n and p is the nominal state of the motor 105b, which can be accessed through the data sheet or the motor.

[0052] Using the linear flux estimation model,

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[0053] The current vector forms a desired angle γ with the magnetic flux vector. λ *Considering that i τ = ||I||sin(γ λ * ), i f = ||I||cos(γ λ * ) is obtained, and from these equations,

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[0054] Therefore, in accordance with the present invention, the equations for the reference torque and current levels are given by the following equations:

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[0055] FIG. 5 illustrates an example block diagram of a direct flux vector control module in accordance with the present invention.

[0056] The direct flux vector control module 102 includes two subtraction modules 500 and 502 and proportional integral filters 501 and 503 .

[0057] The subtraction module 500 subtracts the estimated norm of the magnetic flux vector

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[0058] The output of the subtraction module 500 is provided to a proportional integral filter 501, which calculates a voltage reference V on the f-axis. f * to provide.

[0059] As a result of PI control, the voltage vector V f * is driven so that the estimated flux norm is equal to the reference flux norm.

[0060] The subtraction module 502 subtracts the estimated current of the magnetic flux vector

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[0061] The output of the subtraction module 502 is provided to a proportional integral filter 503, which calculates a voltage reference V on the τ axis. τ * to provide.

[0062] As a result of PI control, the voltage vector V τ * is driven so that the estimated current is equal to the reference current level.

[0063] The coefficients of the PI filter are determined by the given controller bandwidth ω DFVC is set according to

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[0064] For example, ω f =2πf f rad / s, ω τ =2πf τ rad / s, where f f and f τ belongs to [50..500]Hz. τ represents the inductance of the machine on the τ axis and is estimated from the machine nameplate characteristics. DFVC control frequency f DFVCThe choice of is related to the expected dynamics of the control, i.e., the ability to drive the estimated flux and current towards the reference flux and current within a given time window. In one variant, the DFVC module can also add a feedforward term (derived from the current level and speed) and / or a decoupling term.

[0065] The high frequency injection module 103 receives the high frequency signal (-1) n V hf Voltage reference V fτ * Overlay it on top.

[0066] The high frequency injection module 103 is shown in FIG.

[0067] FIG. 2 illustrates an example block diagram of a high frequency injection module according to the present invention.

[0068] The high frequency injection module 103 is composed of a conversion module 211 and an addition module 212 .

[0069] The conversion module 211 is

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[0070] In other words, the high frequency injection signal is then parallel to the estimated flux vector and a direction of the flux angle is estimated that drives the high frequency response of the current vector to be parallel to the current, or the high frequency injection signal is perpendicular to the estimated flux vector and a direction of the flux angle is estimated that drives the high frequency response of the current vector to be perpendicular to the current vector.

[0071] The output of the conversion module 211 is the voltage reference V determined by the DFVC module 102. fτ * The result V fτ ** is then transformed into the αβ framework by the framework transformation module 104. For example, the high frequency signal is a sine wave.

[0072] For example, a high frequency signal (-1) n V hf has a fixed amplitude ranging between 5V and 100V and changes polarity with the activation frequency of the DFVC controller. As an example, the activation frequency of the DFVC controller is equal to the switching frequency of the inverter 105a or twice the switching frequency of the inverter 105a. The switching frequency is in the range of [1..50] kHz.

[0073] An example of the framework conversion module 104 is shown in FIG.

[0074] The framework transformation module 104 estimates the magnetic flux direction

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[0075] The measurement module 107 measures the motor current vector i abc The motor currents measured in the three phases areabc Let i be the measured motor current vector in the αβ framework. αβ Convert to.

[0076] Motor current vector i αβ is provided to a flux angle estimation module 108 and a flux level and current perpendicular to the estimated direction of flux estimation module 109.

[0077] An example of a flux angle estimation module 108 is disclosed with reference to FIG.

[0078] FIG. 3 illustrates an example block diagram of a flux estimation module according to the present invention.

[0079] The magnetic flux angle estimation module 108 is composed of two filters 311 and 321 , an angle detection module 312 , a framework transformation module 313 , two multipliers 322 and 323 , a proportional integral filter 324 , and an integrator 325 .

[0080] The filter 311 is a filter for the current vector i αβ The sample of current vector i αβ The sample is added to the preceding sample.

[0081] The angle detection module 312 detects the angle γ of the current vector projected onto the α axis. α and provides the angle of the current vector in the α axis to the framework transformation module 313.

[0082] The framework conversion module 313 is

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[0083] With respect to the rotation angle (γα +θ inj Only the orthogonally projected (on the +π / 2 axis) transformed current vector is provided to filter 321 .

[0084] The filter 321 is the current vector

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[0085] The output of filter 321 is multiplied by (-1) n-1 is multiplied, i.e., the polarity of the HF voltage injected in the previous activation of the high frequency injection module 103 is used. The function of the multiplier 322 is similar to a simplified heterodyne demodulation applied to a square wave. The invention applies equally to other injection types where the multiplier 322 can be replaced with a heterodyne demodulator.

[0086] The output of multiplier 322 is multiplied by 1 / i0 by multiplier 323 .

[0087] The HF response current is then first heterodyne demodulated, and then a proportional-integral filter 324 drives the output of the heterodyne demodulation to zero. The output of the proportional-integral filter 324 is an estimate of the motor speed.

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[0088] The coefficients of the integral filter 324 are proportional integral filter bandwidth ω δ According to this, it is set as follows:

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[0089] For example, ω δ = 15rad / s. Proportional integral filter bandwidth ω δ is involved in anticipatory dynamics that tracks any changes in velocity.

[0090] The resulting gain of the integrating filter is given by the following equation:

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[0091] In a preferred embodiment, d and l q The approximate value of is the nameplate characteristic (T n : Nominal torque, I n :Nominal current, P n :Nominal power, ω n : Nominal electrical speed, PF=cos(φ n ): nominal power factor, p: number of pole pairs).

[0092] Considering that the current phase angle ψ is about 55 degrees in the nominal state, the nominal torque is

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[0093] From the power factor at the nominal operating point, assuming unitary efficiency of the drive, the reactive power is

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[0094] Finally, assuming the machine is magnetically linear, we obtain

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[0095] The output of the flux angle estimation module 108 is provided to a flux level and current perpendicular to the estimated direction of flux estimation module 109 and to the framework transformation module 104 .

[0096] An example of a magnetic flux level and current perpendicular to the estimated direction of magnetic flux estimation module 109 is disclosed with reference to FIG.

[0097] FIG. 4 shows an example of a block diagram of a module for estimating the magnetic flux level and the current perpendicular to the estimated direction of the magnetic flux according to the present invention.

[0098] The estimation module 109 of the magnetic flux level and of the current perpendicular to the estimated direction of the magnetic flux comprises a framework transformation module 400 and a multiplier 401 .

[0099] Current vector i αβ is the estimated direction of magnetic flux

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[0100] According to the invention, the norm of the flux vector is assumed to be linear with the current in the flux axis and is assumed to be constant for the nominal operating condition I, which can be accessed through the nameplate characteristics of the machine. n , λ n , φ n It can be calculated by the following formula:

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[0101] The estimated flux level is then estimated from the current projected onto the axis of the estimated flux using a fixed ratio determined from the motor's nameplate characteristics.

[0102] The estimated value

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[0103] FIG. 6 is a diagram illustrating an example of a torque reference estimation module according to the present invention.

[0104] The torque reference estimation module includes a subtraction module 600 and a proportional-integral filter 601 .

[0105] The subtraction module 600 subtracts the velocity reference ω * Speed ​​estimate from

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[0106] As a result of the proportional-integral filter 601, a torque reference T * is the estimated speed

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[0107] The coefficients of the proportional integral filter 601 are the bandwidth ω speed According to this, it is set as follows:

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[0108] FIG. 7 is a diagram depicting a motor framework for use with the present invention.

[0109] The stator (αβ) framework is fixed. The current stator (ij) framework is at an angle (γ α) where the angle is defined by the current vector i aligned with the i axis. The flux stator (fτ) framework is at an angle (δ) to (αβ). α ), where the angle is defined by the magnetic flux vector λ aligned with the f-axis.

[0110] According to the present invention, the CCAL module calculates the angle between the i vector and the λ vector based on γ λ * From the torque reference, we obtain the reference amplitude of the magnetic flux, ||λ|| * and the reference current level i τ * Request.

[0111] According to the present invention, the HF injection module 103 is configured to inject a magnetic flux in a direction θ inj The flux angle estimation module estimates the HF response of current vector i at the same angle θ inj Estimate of the angle of the stator flux framework that drives the

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[0112] These formulas use proportionality rules identified from the machine nameplate characteristics to convert the estimated level of flux to the observed current i on the f axis. f Relates to the level of

[0113] Figure 10 shows measurements taken on a commercial synchronous reluctance motor using different angles versus an ideal MTPA system.

[0114] The horizontal axis of FIG. 10a represents the current on the d-axis expressed in amperes.

[0115] The vertical axis of FIG. 10a represents current on the q-axis expressed in amperes.

[0116] The horizontal axis of FIG. 10b represents current at torque expressed in Nm.

[0117] The vertical axis of Figure 10q represents the absolute value of the current in the dq framework expressed in amperes.

[0118] The ideal MTPA trajectory is shown in the curves labeled 10a and 10b. In accordance with the present invention, two different fixed angles γ λ The actual trajectories of are shown in curves 11a, 11b, 12a and 12b.

[0119] angle γ λ When is improperly chosen, for example 15 degrees, the current trajectory deviates significantly from the ideal trajectory, as shown by curves 12a and 12b, resulting in higher levels of current for a given torque and therefore losses.

[0120] angle γ λ When is appropriately selected in accordance with the present invention, e.g., 30 degrees, the current trajectory also deviates from the ideal trajectory as shown in curves 11a and 11b, but the current level will be similar to that of the MTPA in curves 10a and 10b.

[0121] FIG. 9 is a diagram showing an example of an algorithm for controlling a motor according to the present invention.

[0122] The algorithm is disclosed in one example executed by a processor 1100 of a direct flux vector controller of a motor.

[0123] In step S90, the processor 1100 calculates a torque reference T * Request.

[0124] In step S91, the processor 1100 determines a predetermined angle γ λ * Get the.

[0125] Predetermined angle γ λ is the angle of the current vector in the fτ frame and is equal to the difference between the current phase angle and the flux phase angle.

[0126] In a first variant of the invention, the predetermined angle γ λ is set in the range of 30 degrees to 45 degrees.

[0127] The predetermined angle is

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[0128] In a preferred embodiment of the present invention, the predetermined angle is preferably set to a value (e.g., r d = 50 degrees) is dimensioned smaller by, for example, 5 degrees.

[0129] In another variant of the invention, the predetermined angle γ λ is determined as a function of torque stored in a look-up table. For example, at high speed, the MTPA trajectory can be obtained along with inductance data. From such data, the torque can be adjusted to the optimum predetermined angle γ λ At low speeds, a function can be constructed that relates λ is set from the determined torque level.

[0130] In another variation of the invention, the current to torque reference ratio is determined by the angle γ λand varying torque reference levels. The optimum angle is determined as the angle that minimizes the measured current to torque reference ratio, relative to the torque reference determined in step S90.

[0131] In step S92, the processor 1100 determines a flux reference and a current reference from the torque reference and the predetermined angle.

[0132] The flux reference is determined using a first function of the motor's nominal parameters multiplied by the square root of the product of the torque divided by the tangent of the reference angle, and the current reference is determined using a second function of the motor's nominal parameters multiplied by the square root of the product torque reference multiplied by the tangent of the reference angle.

[0133] The first function is

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[0134] Magnetic flux reference λ * and current reference i τ * is calculated according to the following formula:

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[0135] In step S93, the processor 1100 determines the reference voltage to be provided to the motor in a manner similar to that performed by the DFVC 102 of FIG.

[0136] In step S94, the processor 1100 injects a high frequency signal into the reference voltage in a manner similar to that injected by the high frequency injection module 103 of FIG.

[0137] In step S95, the processor 1100 obtains motor current vector measurements in a manner similar to those measured by the current measurement module 107 of FIG.

[0138] At step S96, the processor 1100 determines an estimate of the direction of the motor's flux from the motor current vector in a manner similar to that performed by the flux angle estimation module 108 of FIG.

[0139] At step S97, the processor 1100 determines from the estimate of the direction of the magnetic flux an estimate of the magnetic flux and an estimate of the current perpendicular to the estimated direction of the magnetic flux in a similar manner as that determined by the estimation module 109 of FIG.

[0140] In step S98, the processor 1100 provides an estimate of the magnetic flux and an estimate of the current perpendicular to the estimated direction of the magnetic flux to the direct flux vector control step S92.

[0141] FIG. 11 is a diagram illustrating a second example of a direct flux vector controller for a motor using a constant current angular trajectory in accordance with the present invention.

[0142] The direct flux vector controller 11 for a motor using constant current angular trajectory has, for example, an architecture based on components connected by a bus 1101 and a processor 1100 controlled by the program disclosed in FIG.

[0143] The bus 1101 links the processor 1100 to a read-only memory ROM 1102 , a random access memory RAM 1103 and an input / output I / O IF interface 1105 .

[0144] The input / output I / O IF interface 1105 enables the direct flux vector controller 11 to sense a signal representative of the current flowing through the motor 105b.

[0145] The memory 1103 includes registers for containing variables and instructions of the programs related to the algorithm disclosed in FIG.

[0146] The read-only memory, or possibly the flash memory 1102, contains instructions of the program related to the algorithm disclosed in Figure 9. These instructions are loaded into the random access memory 1103 when the device 11 is powered up. Alternatively, the program can be executed directly from the ROM memory 1102.

[0147] The calculations performed by device 11 may be implemented in software by a programmable computing machine such as a PC (Personal Computer), DSP (Digital Signal Processor) or microcontroller executing a set of instructions or programs, or alternatively in hardware by machines or dedicated components such as an FPGA (Field-Programmable Gate Array) or ASIC (Application-Specific Integrated Circuit).

[0148] In other words, device 11 includes circuitry, or a device including circuitry, that causes device 11 to execute a program related to the algorithm disclosed in FIG.

Claims

1. 1. A method for controlling a motor using a direct flux vector control module and a constant current angular trajectory module, comprising: determining a torque reference; the constant current angle trajectory module determining a flux reference and a current reference from the torque reference and a predetermined angle; providing the flux reference and the current reference to the direct flux vector control module to obtain a reference voltage provided to the motor; injecting a high frequency signal into the reference voltage; determining an estimate of the direction of the motor flux from a motor current vector; determining an estimate of the norm of the magnetic flux and an estimate of a current flowing perpendicular to the estimated direction of the magnetic flux from the estimate of the direction of the magnetic flux; providing the estimate of the norm of the magnetic flux and the estimate of the current flowing perpendicular to the estimated direction of the magnetic flux to the direct flux vector control module; A method comprising:

2. 2. The method of claim 1, wherein the flux reference is determined using a first function of the motor nominal parameters multiplied by the square root of the torque product divided by the tangent of the reference angle, and the current reference is determined using a second function of the motor nominal parameters multiplied by the square root of the product torque reference multiplied by the tangent of the reference angle.

3. The first function is [0010] and the second function is [0025] where λ ｎ is the nominal magnetic flux of the motor, and I ｎ is the nominal current of the motor, and sin(φ ｎ ) is the nominal power factor cos(φ ｎ 3. The method of claim 2, wherein p is determined from p = p , where p is the number of pole pairs of the motor.

4. The magnetic flux reference λ ＊ and the current reference i τ ＊ is calculated according to the following formula: [0030] Here, λ ｎ is the nominal magnetic flux of the motor, and I ｎ is the nominal current of the motor, and sin(φ ｎ ) is the nominal power factor cos(φ ｎ ), p is the number of pole pairs of the motor, and T ＊ is the torque reference, and γ λ ＊ 2. The method of claim 1, wherein: is the predetermined angle.

5. Method according to any one of claims 1 to 4, characterized in that the predetermined angle is comprised between 30 degrees and 45 degrees.

6. The predetermined angle is [0045] where: [0050] and [006] is the nominal inductance estimated from the nameplate characteristics of the motor, and γ ｄ 5. The method according to claim 1, wherein: = 55 degrees.

7. A method according to any one of claims 1 to 4, characterized in that the predetermined angle is determined as a function of torque stored in a look-up table.

8. 5. A method according to any one of claims 1 to 4, characterized in that the predetermined angle is determined from observed current to torque reference ratios at varying levels of a predetermined angle and varying torque reference levels, and an optimum angle is determined as the angle which minimizes the observed current to torque reference ratio for the determined torque reference.

9. A method according to any one of the preceding claims, characterised in that the estimated flux level is estimated as the current projected on the axis of estimated flux multiplied by a fixed ratio.

10. 10. The method of claim 9, wherein the lock ratio is determined from a nameplate characteristic of the motor.

11. 11. The method according to claim 1, wherein the high frequency injection signal is parallel to the estimated magnetic flux vector, and the angle of the magnetic flux vector that drives the high frequency response of the current vector to be parallel to the current is estimated.

12. 11. The method according to claim 1, wherein the high frequency injection is perpendicular to the estimated magnetic flux vector, and the angle of the magnetic flux vector that drives the high frequency response of the current vector to be perpendicular to the current vector is estimated.

13. 1. A device for controlling a motor using a direct flux vector control module and a constant current angular trajectory module, comprising: A means for determining a torque reference; means for said constant current angle trajectory module determining a flux reference and a current reference from said torque reference and a given angle; means for providing the flux reference and the current reference to the direct flux vector control module to obtain a reference voltage provided to the motor; means for injecting a high frequency signal into said reference voltage; means for deriving an estimate of the direction of the magnetic flux of the motor from a motor current vector; means for determining an estimate of the norm of the magnetic flux and an estimate of a current flowing perpendicular to the estimated direction of the magnetic flux from the estimate of the direction of the magnetic flux; means for providing the estimate of the norm of the magnetic flux and the estimate of the current flowing perpendicular to the estimated direction of the magnetic flux to the direct flux vector control module; A device comprising:

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