阅读说明：本技术 用于估计绕线转子同步机器的转子的速度和位置的方法 (Method for estimating the speed and position of the rotor of a wound rotor synchronous machine ) 是由 M·科泰希 A·梅萨利 M·加恩斯 于 2019-07-02 设计创作，主要内容包括：本发明涉及一种用于对由三相电力网络供电的绕线转子同步机器(50)的转子(50)的速度和位置进行估计的方法,该方法包括：-将高频电压信号注入该三相电力网络中的步骤；-对通过该第二变换步骤(101)变换的电流进行解调的步骤(101),包括高通滤波或带通滤波并用于确定估计误差信号(∈)；-估计(102)由转子加速度以及该解调步骤(101)的高通滤波或带通滤波产生的相移(φ_(comp)),以细化在该解调步骤(101)期间确定的估计误差信号(∈)的步骤；将所测得电流的高频分量与低频分离的步骤(103)；该方法进一步包括用于根据所获得的估计误差的符号,用互不相关的增益参数来逐步估计该转子的位置、速度和加速度的第二部分(12)。(The invention relates to a method for estimating the speed and position of a rotor (50) of a wound rotor synchronous machine (50) supplied by a three-phase electric power network, the method comprising: -a step of injecting a high frequency voltage signal into the three-phase electric power network; -a step (101) of demodulating the current transformed by the second transformation step (101), comprising high-pass filtering or band-pass filtering and used to determine an estimation error signal (e); -estimating (102) the phase shift (phi) resulting from the rotor acceleration and the high-pass filtering or the band-pass filtering of the demodulation step (101) comp )，A step of refining the estimated error signal (e) determined during the demodulation step (101); a step (103) of separating the high frequency components of the measured current from the low frequencies; the method further comprises estimating a second part (12) of the position, velocity and acceleration of the rotor step by step with mutually uncorrelated gain parameters based on the sign of the obtained estimation error.)

1. A method for estimating a speed and a position of a rotor (50) of a wound rotor synchronous machine (50) powered by a three-phase inverter, the method comprising:

-measuring the three-phase current (i) at the input of the wound rotor synchronous machine (50)_a、i_b、i_c) A step (2);

-measuring the three-phase currents (i)_a、i_b、i_c) Transformation into a two-phase reference frameA step (2);

-the first part (11) comprises:

-a step of injecting a high frequency voltage signal at the input of the machine;

characterized in that the first part (11) further comprises determining a rotor position error value comprising:

-transforming (101) the measured converted current into a two-phase reference frame by rotating by pi/4 radiansThe second step of (1);

-a step of demodulating (101) the current transformed by the second transformation step (101), comprising high-pass filtering or band-pass filtering and allowing to determine an estimation error signal (e);

-estimating (102) the phase shift (phi) resulting from the rotor acceleration and the high-pass filtering or the band-pass filtering of the demodulation step (101)_comp) A step of refining the estimated error signal (e) determined in the demodulation step (101);

-a step of separating (103) high frequency components from low frequency components of the measured current; said separating step (103) is independent of low-pass filtering and allows determining the sign of the rotor position estimation error;

the method further comprises estimating a second part (12) of the position, the velocity and the rotor acceleration step by step with mutually independent gain parameters based on the sign of the obtained estimation error.

2. The method of claim 1, characterized in that the demodulation step (101) comprises a high-pass filtering of said current.

3. A method as claimed in claim 1 or 2, characterized in that the phase shift estimation step (102) comprises low frequency filtering.

4. A method as claimed in claim 3, characterized in that the phase shift estimation step (102) comprises a phase locked loop.

5. The method according to any of the claims 1 to 4, characterized in that the step of separating (103) the high frequency components of the measured current from the low frequencies comprises calculating a rotor position estimation error signal defined by the following equation:

wherein, I_cnIs the magnitude of the negative component of the stator current, ω_cIs the angular frequency of the injected high frequency signal, and_compis the estimated phase shift (102), andis the rotor position error.

6. A method as claimed in any one of claims 1 to 5, characterized in that the second part (12) comprises implementing at least one low-pass filter.

7. The method of claim 6, wherein the low pass filter is a 4 th order filter.

8. An apparatus for estimating the speed and position of a rotor, the apparatus comprising means for implementing a method as claimed in any one of claims 1 to 7.

9. An electrical assembly comprising a wound rotor synchronous machine and an estimation device as claimed in claim 8.

10. A motor vehicle comprising the electrical assembly of claim 9.

Technical Field

The invention relates to the field of wound rotor synchronous motors.

More particularly, the present invention relates to a method for determining the position and speed of the rotor of a wound rotor synchronous machine.

Background

In order to control a wound rotor synchronous machine (abbreviated WRSM), it is generally necessary to know the position and speed of the rotor.

One solution known in the prior art comprises mounting one or more mechanical position and speed sensors on the machine shaft of the machine.

However, these mechanical sensors are expensive, bulky, sensitive to the environment (temperature, noise, mechanical oscillations, electromagnetic compatibility, etc.), and can reduce the reliability of the system.

Therefore, in order to avoid the use of mechanical sensors, control methods have been developed that do not use mechanical sensors to ensure the same or even better quality of control compared to methods using mechanical sensors for control.

Typically, these sensorless control methods use a mechanical position/velocity estimation method based only on measurements of current in closed-loop mode, also referred to as software sensors.

Also known are methods for estimating the position/speed of the rotor by injecting high frequency signals, as described in document US 2004070360 a1, which have the effect of allowing detection with less dependence on machine parameters.

However, these methods still depend on the parameters of the machine, and more particularly for WRSM, on the stator inductance experienced by the rotor. In addition, these techniques rely on knowing the characteristics of the injected signal, such as amplitude and frequency.

Therefore, there is a need for a position/speed estimation method that is more reliable and less dependent on the parameters of a wound rotor synchronous machine.

Disclosure of Invention

To this end, a method for estimating the speed and position of the rotor of a wound rotor synchronous machine powered by a three-phase inverter is proposed, the method comprising:

-a step of measuring the three-phase currents at the input of the wound rotor synchronous machine;

-a step of transforming the measured three-phase currents into a two-phase reference frame;

-the first part comprises:

-a step of injecting a high frequency voltage signal at the input of the machine;

wherein the first portion further comprises determining a rotor position error value comprising:

-a second step of transforming the measured converted current into a two-phase reference frame by rotating by pi/4 radians;

-a step of demodulating the current transformed by the second transformation step, comprising high-pass filtering or band-pass filtering and allowing to determine an estimation error signal;

-a step of estimating the phase shift resulting from the rotor acceleration and the high-pass or band-pass filtering of the demodulation step, so as to refine the estimated error signal determined in the demodulation step;

-a step of separating the high frequency components from the low frequency components of the measured current; said separating step is independent of the low-pass filtering and allows to determine the sign of the rotor position estimation error;

the method further comprises estimating step by step the position, the velocity and a second part of the rotor acceleration with mutually independent gain parameters based on the sign of the obtained estimation error.

Thus, a relatively simple and robust estimation of the position, velocity and acceleration of the wound rotor can be obtained only from the sign of the obtained estimation error (which sign is defined from the error signal calculated by injecting the high frequency voltage). This makes it possible in particular to obtain rotor position, speed and acceleration estimates, which are calibrated independently of one another and more particularly by gains which are independent of one another.

Advantageously and in a non-limiting manner, the demodulation step comprises a high-pass filtering of said current. Thus, the demodulation is relatively simple and robust, and does not produce a delay with respect to the estimate obtained for the rotor position.

Advantageously and in a non-limiting manner, the phase shift estimation step comprises low frequency filtering. Thus, the estimation of the phase shift is relatively simple and efficient.

Advantageously and in a non-limiting manner, the phase shift estimation step comprises a phase-locked loop. Thus, the estimation of the phase shift is controlled relatively robustly.

Advantageously and in a non-limiting manner, the step of separating the high frequency components from the low frequency components of the measured current comprises calculating a rotor position estimation error signal defined by the following equation:

wherein, I_cnIs the magnitude of the negative component of the stator current, ω_cIs the angular frequency, phi, of the injected high frequency signal_compIs the estimated phase shift, andis the rotor position error.

Thus, the sign of the rotor position error may simply be determined from the estimation error signal, thereby making it possible to then implement the second part of the method to obtain a simple and robust estimation of the speed, position and acceleration of the rotor.

Advantageously and in a non-limiting manner, the second part comprises implementing at least one low-pass filter. The low pass filter makes it possible to limit the jitter phenomenon of the rotor position error sign function.

In particular, the low-pass filter is a 4 th order filter. Thus, such a filter does not have undesirable effects (such as phase shift) on the estimation of the speed, position and acceleration of the rotor.

The invention also relates to a device for estimating the speed and position of a rotor, comprising means for implementing the method as described above.

The invention also relates to an electrical assembly comprising a wound rotor synchronous machine and an estimation device as described above.

The invention also relates to a motor vehicle comprising an electrical assembly as described above.

Drawings

Further particular features and advantages of the invention will become apparent from reading the following description of particular embodiments of the invention, given by way of indication and not limitation, with reference to the accompanying drawings, in which:

figure 1 is a schematic view of a control assembly of an electric machine according to an embodiment of the invention;

FIG. 2 is a schematic illustration of an estimation method according to an embodiment of the invention;

figure 3 is a representation of the step of estimating the phase shift of the stator current according to the method of the embodiment of figure 2;

fig. 4 is a representation of a high/low frequency separation step independent of a low pass filter of the method according to the embodiment of fig. 2;

FIG. 5 is a view of a second estimation portion of the method according to the embodiment of FIG. 2; and

FIG. 6 is a representation of the geometric transformation of the current with respect to the rotor reference frame,

and figure 7 is a representation of a continuous algorithm according to equation (12).

Detailed Description

Referring to fig. 1, a control assembly of an electric machine 1 (here, for example, an electric vehicle 1) includes a torque setpoint device 2 (e.g., an accelerator pedal 2) for requesting torque from the electric machine.

The torque setpoint generated by the torque setpoint device 2 is then processed by the current regulator 3 and then by the inverter 4 to supply the appropriate control current to the motor 5 (here the wound rotor synchronous motor 5).

In order to allow an efficient control of the machine, it is necessary to know the position of the rotor of the machine (in other words the angular position of the rotor with respect to the stator), its speed and advantageously its acceleration. For this purpose, an estimation method 6 is implemented.

Since fig. 2 to 6 relate to the same embodiment of the estimation method according to the invention, these figures will be discussed simultaneously.

A method for estimating the speed and position of the rotor 50 of a 6-wound rotor synchronous machine includes the steps of measuring 10 three-phase currents and two method parts: a first part 100 comprising signal processing and demodulation and a second part 200 comprising estimating position and velocity from the results of the first part.

Firstly, the method implements a measurement of the three-phase current i at the input of a 10-wound-rotor synchronous machine_a、i_b、i_cThe step (2). However, this step does not have to be performed before the first part 100 of the method, but it can also be performed during the first part 100 of the method, for example, when the need relates to the measured three-phase current values i_a、i_b、i_cAnd previously executed.

Then, the measured three-phase currents i_a、i_b、i_cTransformed into a two-phase reference frame α β.

For this purpose, a transformation is applied in the rotor reference frame 50, as shown in fig. 6. Thus, based on the measured three-phase currents i_a、i_b、i_cDeriving i for the measured two-phase current by applying the following equation_α(k)

System i_β(k)：

This equation (1) describes the three-phase current i according to a static three-phase to two-phase transformation 13, here a kenkokia (concodia) transformation, to a reference system α β_a、i_b、i_cThe measurement result of (1).

To model the high frequency behavior of a synchronous machine, a model based on the following two equations is then applied:

voltage-flux model:current-flux model:

wherein the content of the first and second substances,andrespectively the average inductance and the differential inductance of the machine, L_dAnd L_qAre the inductances on the axes d and q of a rotating two-phase reference frame d-q which is a Park reference frame,andrespectively representing the three-phase voltage and current of the machine seen on the stator, andis the stator flux of the machine),

in order to estimate the position, speed and acceleration of the ac machine, a so-called pulsating technique is implemented, in which a two-phase reference frame is estimated(the estimated reference frame represents the estimated park reference frame) the offset of the measurement of the current in the current isThus, the reference system of axes dm and qm and the injection axisAndis offset from the reference frame

On the axisUpper high frequency voltage is injected and the current is measured on the axis dm and on the axis qm.

Referring to fig. 6, the angular phase shift is particularly represented in the rotor reference frame 50.

The ripple technique makes it possible to inject a High Frequency (HF) voltage into the estimated two-phase reference frameThe method comprises the following steps:

wherein:

V_cis the amplitude of the injected HF voltage; and

ω_cis the angular frequency of the injected HF voltage.

Referring to FIG. 6, an offset from the injection reference frame is obtained as followsIn the reference system of

Wherein the content of the first and second substances,andamplitude I of the positive component, respectively_cpAmplitude of the negative component I_cnAnd the fundamental component of the stator currentθ is the position of the rotor, andis the estimated position of the rotor.

Then a step 101 of demodulating the resulting signal after injecting the high frequency voltage is carried out.

For this purpose, a high-pass filter (abbreviated to HPF) or, according to an alternative, a band-pass filter (single-frequency filter, abbreviated to SFF) is used to phase-shiftIn the reference system ofFiltering is performed to remove its fundamental component.

The resulting high frequency current is obtained according to the following equation

It is developed by trigonometric functions to yield:

in this deployment, the differenceIs used to extract the position estimation error signalPosition estimation error signalCorresponds to the demodulation 101 of the signal.

The estimated error signal ∈ is formulated according to equation (7), and the angle error between the position of the rotor and the estimated position of the rotorIs a function of the estimated error signal e.

Thus, by analyzing the estimation error signal e, as described below, it will be possible to derive a position error from the sign of the estimation error signal eThe symbol of (2). Position errorMakes it possible to determine an estimate of the position, speed and acceleration of the rotor in the second part of the method.

Once the estimated error signal e has been obtained according to equation (7), in other words once demodulation has been performed, a phase shift estimation step 102 is implemented, as shown in fig. 3.

The speed variation during the acceleration phase of the machine will be at the signal carrier level (cos (ω)_ct+φ_acc) To produce a phase shift phi_acc。

The high-pass filter HPF is used in the demodulation step 101, or according to an alternative, a band-pass filter (single-frequency filtering, abbreviated SFF), also at the carrier level (cos (ω) of the signal_ct+φ_HBF) To produce a phase shift phi_HBF。

Thus, the signal of the carrier experiences these delays, and its expression (as previously formulated in equation (7)) becomes:

∈＝Acos(ω_ct+φ_comp) (8)

wherein the content of the first and second substances,and phi_comp＝φ_HBF+φ_acc。

To extract the position estimation error in term A, one multiplies e by termTherefore, the phase shift phi needs to be estimated_comp。

By multiplying the estimated error of equation (8) by a termThe following formula is obtained:

and

by applying a low pass filter (abbreviated LPF), the following is obtained:

and, by applying a continuous algorithm (here phase locked loop, abbreviated PLL) to (11), the phase shift phi can be calculated_compEstimation of (2):

the pair of phase shifts phi_compThe estimation of (b) then makes it possible to obtain:

and thus

In particular, the purpose of estimating the phase shift is to reconstruct the high frequency carrier signalTo obtain the square of this component, the square of the carrier (high frequency) [ cos (ω) ]_ct+φ_comp)]²Or phi_compIs an unknown quantity.

The above calculation makes it possible to estimate the phase shift phi_compThe phase shift being equal to after convergence of the estimate

Therefore, the phase shift estimation error is sent to a continuous sum error optimization (PLL) step (refer to fig. 7) so thatConverge on phi_comp。

Then, step 103 of separating the high frequency components from the low frequencies is carried out, so that the use of Low Pass Filters (LPFs) can be avoided. In the following description, this is referred to as an LPF estimation step 103.

An estimation error e containing the position of the machine has been previously determined so that the estimation error can be expressed according to the following equation:

by making the estimated error contain a phase shiftMultiplying the terms of (a) to obtain the following formula:

in the context of salient pole wound rotor machines (called salient pole rotor machines), because of L_q＞L_dTherefore, it isand-I_cn＞0。

Thus:

wherein:

wherein the term symbol denotes "a symbol of an included expression".

The sign of the position estimation error is described in terms of the expression of equation (15) without using conventional techniques based on Low Pass Filters (LPFs).

This estimation error according to equation (15) is then injected as information into a set of successive steps 200 according to the invention, step by step and converging in a limited time.

This set of steps 200 corresponds to the second part 200 of the method according to the invention, the purpose of which is to estimate the position, speed and acceleration of the ac motor.

In the second part 200, in order to make the process of setting up the techniques for estimating position, velocity and acceleration straightforward, an estimator (also called an observer), which is robust and acts stepwise (as shown in fig. 4), is implemented so that the position, velocity and acceleration states converge one after the other independently of one another. This makes it possible to set the states to converge in a limited time, with each state being considered separately.

When the estimated position is expressed according to equation (19)When regarded as being equal to the actual position θ, in other words, when considering the position errorApproximately considered zero:

if it is not

Then

Now, the only measurement of the estimator is:

obtained from the first part 100 of the method

The proposed robust step-by-step observations for estimating position, velocity and acceleration are defined by the following equations:

wherein:

wherein the content of the first and second substances,

and

and

wherein the content of the first and second substances,

where TZ denotes a Z-transformation which makes it possible to transform a time function σ (t) into a discrete function σ (Z).

The function f (z) is introduced to detect the phenomenon of jitter, since only the sign of the estimation error is available as information of the observed quantity; the position of the rotor is not available for measurement.

To obtain filtered velocityAnd accelerationImplementing a 4 th order Low Pass Filter (LPF) used in the second part 200 of the method, see fig. 5. These low pass filters are introduced to reduce the jitter phenomena of the sign function and do not affect the position, velocity and acceleration estimates, since these estimates are advantageously uncorrelated with each other.

The virtual mechanical system for observing the designed position, velocity and acceleration of the quantities (21), (22) and (23) is as follows:

equations (33), (34), and (35) define the estimation errors of position, velocity, and acceleration between equations (30) - (31) - (32) and observed quantities (21) - (22) - (23):

the estimation error dynamic range is derived from the following equation:

wherein, K_θ＞Max(|e_ω|)、K_w＞Max(|e_αI) and K_αThe gain > 0 defines a positive value to limit noise.

It is thus clear that the method according to the invention ensures that the estimation error dynamic ranges (36) - (37) - (38) of position, velocity and acceleration converge to zero in a limited time.