EP3195467A1

EP3195467A1 - Method and device for diagnosing phase current sensor defects in a system for controlling a synchronous rotary electrical machine of a motor vehicle

Info

Publication number: EP3195467A1
Application number: EP15771683.8A
Authority: EP
Inventors: Sidath DIAO; Zaatar MAKNI; Demba DIALLO
Original assignee: Valeo Equipements Electriques Moteur SAS
Current assignee: Valeo Equipements Electriques Moteur SAS
Priority date: 2014-09-17
Filing date: 2015-09-10
Publication date: 2017-07-26
Also published as: WO2016042238A1; FR3025890B1; US10718845B2; CN107112943B; US20170254872A1; CN107112943A; FR3025890A1; JP2017533688A

Abstract

The method according to the invention enables the diagnosis (15, 16) of phase current sensor defects in a system for controlling a synchronous rotary electrical machine of a motor vehicle. According to the invention, the method takes into account the differences (î_d, l_q) between measurements provided (14) by the sensors, and nominal values of the phase currents (i_a, i_b, i_c) in order to diagnose defects. Said differences are calculated (18) in a rotating Park reference frame (17) and are separate from an electromechanical model of the machine. The method detects sensor defects if the differences are substantially non-zero (19) and an offset sensor defect if a residual pulsation (ω _res) of the differences is substantially equal to a measured speed (w) of the control system.

Description

METHOD AND DEVICE FOR DIAGNOSING STATIC CURRENT SENSOR FAULTS OF A DRIVING SYSTEM OF A SYNCHRONOUS MOTOR VEHICLE ROTARY ELECTRIC MACHINE

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method and a device for fault diagnosis of phase current sensors of a control system of a synchronous rotating electric machine of a motor vehicle,

The invention also relates to a synchronous rotary electrical machine comprising such a device, in particular a machine such as a permanent magnet synchronous electric motor for applications in electric and hybrid motor vehicles, electrical power steering, air conditioning compressors and electric motors. fans.

BACKGROUND ART OF THE INVENTION.

The number of electronic equipment and electrical functions in embedded systems in vehicles is steadily increasing. This is due to their great flexibility of use, their compactness and their low maintenance constraint.

However, their availability and reliability are an issue because they can be prone to breakdowns.

Therefore, mechanisms are provided very early, from the design phase, to facilitate fault detection, diagnosis and appropriate reconfiguration of orders.

Many works have been carried out in the field of fault detection of electrical control systems and their characterizations.

The cases of the current sensors, the angular position sensor, and the DC voltage sensor of a control of a synchronous motor with permanent magnets are known from the state of the art, and good experimental results have been obtained, but few details are given on the issue of fault isolation in the case of current sensors. For those skilled in the art, the most used method for the detection and characterization of the defect (FDI in English terminology, acronym for "Fault Detection and Isolation") is based on the observation of the behavior of the real system with respect to a theoretical model. .

The differences that appear allow you to decide whether the system has a default or not.

However, this method has many disadvantages.

It requires in particular to build a model taking into account all the variables of state of the system, and it is difficult to model the disturbances, due to the resisting torque or the variation of speed for example, which are not defects.

To overcome these drawbacks, it has been proposed in the article "Current Sensor Fault Diagnosis in Stationary Frame for PMSM Drive in Automotive Systems", S. Diao et al., 2014 Ninth International Conference on Ecological Vehicles and Renewable Energies (EVER), IEEE, an alternative based on an estimate from a system of differential equations of a dynamics of a difference between measured phase currents and nominal phase currents.

However, the estimators used involve electrical parameters which are not independent of the machine and are calculated in a stationary reference which does not make possible all possible simplifications in the case of a control system.

GENERAL DESCRIPTION OF THE INVENTION

The object of the present invention is therefore to take into account the properties of a control system to simplify the calculations of these differences.

According to a first aspect, the invention relates to a method for diagnosing phase current sensor faults of a control system of a synchronous rotating electrical machine of a motor vehicle.

According to the invention, the method takes into account differences T _d , _q between measurements provided by the sensors and nominal values of the phase currents in order to diagnose faults if the differences are substantially non-zero, these differences being calculated in a park marker in rotation and being independent of an electromechanical model of the machine, a defective sensor among the sensors being identified by comparing at an angle electrical measured Θ of the control system a residual electrical angle 0 _res defined by the relation:

0, _es = arctan (- T _q / T _d )

where T _d and T _q are the said differences.

According to a particular characteristic of the method according to the invention, an offset defect of at least one of the sensors is detected if a residual pulse of the differences is substantially equal to a measured speed of the control system.

According to another particular characteristic, a gain defect of at least one of the sensors is detected if a residual pulse of the differences is substantially equal to twice a measured speed of the control system.

According to another aspect, the invention also relates to a device for diagnosing phase current sensor defects of a control system of a synchronous rotating motor vehicle electrical machine capable of implementing the method described briefly below. above, of the type comprising:

means for acquiring measurements provided by the sensors and an electric angle of the control system;

digital processing means of the measurements; and

flag generation means signaling sensor faults.

According to the invention, the processing means perform a Park transformation and comprise means for analyzing waveforms of the phase currents in the Park reference, the means for analyzing waveforms including means calculating a sliding average over time.

According to a particular characteristic of the diagnostic device according to the invention, the acquisition means also acquire a speed of the control system and the processing means furthermore comprise means for detecting an offset defect and / or a gain defect of at least one of the sensors as a function of said speed.

According to another particular characteristic, the processing means further comprise means for identifying a faulty sensor among the sensors as a function of the electric angle.

According to other aspects, the invention also relates to a synchronous rotary electrical machine comprising a diagnostic device as briefly described above, and a semiconductor computer memory. intended to be integrated in the diagnostic device and containing a computer code representative of the method of the invention.

These few essential specifications will have made obvious to the skilled person the advantages provided by the method and the device for diagnosing phase current sensor faults of a control system of a synchronous rotary electric machine of a motor vehicle according to the invention. invention, as well as by the synchronous rotating electrical machine and the associated computer memory, compared to the state of the prior art.

The detailed specifications of the invention are given in the following description in conjunction with the accompanying drawings. It should be noted that these drawings have no other purpose than to illustrate the text of the description and do not constitute in any way a limitation of the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a general block diagram of a control system of a synchronous rotating electrical machine.

Figure 2 is a block diagram of a control unit of the control system of a synchronous rotating electrical machine shown in Figure 1 incorporating a phase current sensor fault diagnosis device according to the invention.

FIG. 3 is a flowchart illustrating the method according to the invention of fault diagnosis of phase current sensors of a control system of a synchronous rotating electrical machine. DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

A control system 1 of a synchronous rotary electrical machine 2, such as that shown in FIG. 1, generally comprises a control unit 3 controlling an inverter 4 supplying the synchronous electric machine 2 with current from a voltage source continuous 5.

Measurements of the voltage V _beats from the DC voltage source 5, the phase currents 4, i _b , i _c corresponding to the three phases A, B, C, of the electrical angle Θ and the speed ω associated with the instructions torque Γ ^θί and speed u) ^ref , are the usual inputs of the control unit 3. This control unit 3 generates the control signals U, V, W of the inverter 4 so that the synchronous electrical machine 2 provides the required torque Γ ^θί at the specified speed ω ^Γθί , parameters most often transmitted on a bus of ground 6.

Figure 2 shows the main elements of the control unit 3.

The electrical angle Θ of the control system 1 is supplied to the control unit 3 by a position sensor 7 of a rotor 8 of the synchronous rotating electrical machine 2.

The speed ω is provided by a speed sensor 9, or by a calculation from the electric angle Θ.

The measurements of the phase currents 4, i _b , i _c , are provided by phase current sensors 10.

It is precisely these phase current sensors 10 which may have defects, either an offset defect or a gain defect.

These defects are obviously detrimental to the proper functioning of the control system 1 of the synchronous rotating electrical machine 2, and it is necessary to detect them and to characterize the faulty sensor.

The purpose of the control unit 3 is to allow efficient operation of the control system 1 in a wide range of torques and speeds.

To do this, a closed control loop is required 1 1. The closed control loop 1 1 is a corrector which ensures a good control of the phase currents measured from a reference current f ^ef .

A reference current calculation block 12 gives this reference current f ^ef from the torque references Γ ^θί or speed ω ^Γθί , and electrical parameters of the rotating electrical machine 2.

This reference current calculation block 12 transforms a mechanical reference into an electrical reference.

After the reference voltages V ^ref have been calculated by the closed control loop 1 1, the pulse width modulation control block 13 generates the pulse width modulated control signals U, V, W (or PWM, acronym for "Pulse Width Modulation" in the English terminology) of the inverter 4.

With regard to the closed control loop 1 1, since it is a control system 1, the control can be achieved in different marks. The well-known Clarke transformation is a projection of phase magnitudes on two fixed axes (α, β).

Then the transformation of Clarke can be followed by a rotation that converts the alternative components of the coordinate system (α, β) .βη continuous components on direct and quadrature axes (the reference (d, q)).

The combination of a Clarke transformation and a rotation of the mark (α, β) to the mark (d, q) is usually called a Park transformation.

The main advantage of these transformations is a reduction in the order of the system (from 3 to 2) and a decoupling of the control variables,

Effective control of an electrical control system 1 requires that the instantaneous currents 4 _, 4, 4 are well known. For reliable operation of the electrical control system 1, the control strategy must be tolerant to a sensor fault 10. Then, the continuity of operation is ensured and the security constraints are met.

Currently, in the most demanding applications, hardware redundancy is used to overcome a sensor failure 10. This solution makes the design of the electric control system 1 more complex and increases the cost.

On the other hand, a software redundancy is much more interesting because of its capacity of evolution in addition to its low cost. For this purpose, a diagnostic method based on an analysis of the waveforms of the currents in a rotating reference mark (d, q) is developed.

This method, illustrated in FIG. 3, only needs the phase currents 4 _, 4, 4 provided at the input 14, the electrical angle Θ and the speed ω to detect and identify the faulty sensor among the set Phase current sensors 10.

It is assumed that a single sensor 10 fails, but this assumption is realistic because the probability of the simultaneous failure of two sensors is very low.

The analysis of the waveform of the currents in the rotating reference is detailed below.

The equations of the currents are first given in the natural coordinate system (a, b, c) and in the Park coordinate system (d, q) in the usual operating mode, or nominal, in the absence of sensor fault 10 (the index h indicates variables in this mode).

In the natural coordinate system (a, b, c), we have the following nominal values:

i _a , h = l∞s (0) ib, h = l∞s (0 -y) i _c , h = lcos (0 +)

In the Park reference (d, q), we calculate 17:

The consequence of a faulty sensor is then modeled in a first case of an offset defect and in a second case of a gain defect.

In the first case, the measurements provided by the phase current sensors 10 are written for each of the three phases A, B, C:

lam ⁼ la, h ⁺ Δ / ₉

'bm ⁼ lb, h ⁺ Δ¾

or:

Ai _a , Ai _b and Ai _c are the offsets on phases A, B and C respectively.

4 m, ibm and i _cm are the measurements provided by the phase current sensors 10 of the phases A, B and C respectively.

Differences T _d , _q between the measurements and the nominal values are obtained in the Park coordinate system by means of the equalities:

d, h 'dm q ^~ lq, h' dm

When the nominal values i _dh and i _qh are not known, they can be approximated by applying a rolling average over time to the values of the currents.

We have for each of the phases A, B and C: PhaseA PhaseB PhaseC

In the rotating mark, the currents i _dh , _h are continuous in nominal mode. When an offset fault occurs on one of the three phase current sensors 10, a sinusoidal component ï _dq is added to the DC currents id.h, iq.h at the electrical frequency.

If the differences 7 _d , _q are substantially zero (with the noise), in the method according to the invention Flag Flags A, B, C 20 are generated representative of the absence of defect of the sensors 10 (Flag_A, B, C = 0).

On the other hand, if the differences 7 _d , _q are substantially nonzero 19, in the method according to the invention, an analysis of the waveform 21 of the phase currents in the Park reference is carried out by defining a residual electric angle. 0 _res by the relation 0 _res = arctan (- T _q / T _d ), and calculating a residual pulsation u) _res by the expression u) _res = d0 _res / dt.

In the first case of an offset defect, this residual pulse u) _res is equal (to computational errors and measurement close) to the speed ω, and, in the second case of a loss of gain, this pulsation residual u) _res is equal to twice the speed ω, as will be shown below.

This analysis of the waveform 21 of the phase currents in the Park coordinate system makes it possible in the method according to the invention to decide on the absence of a sensor fault (Flag_A, B, C = 0) 23 if no component alternative to frequencies ω / 2π or ω / π is detected.

If an alternating component is detected, in the method according to the invention, the fault is confirmed and a comparison 16 of the residual electric angle θ _res at the electrical angle Θ makes it possible to determine the phase A, B, C corresponding to the defective sensor among the three phase current sensors 10:

PhaseA PhaseB PhaseC

According to the method of the invention, flags Flag_A, B, C are then generated. 24 representative of the presence of a fault on one of the phase current sensors 10 (Flag_A, B, C = ^* \).

In the second case of sensor fault (gain defect), the measurements i _am , ibm, icm provided by the phase current sensors 10 are written to each other.

i _am

where G _a , G _b , G _c are the gains of the current sensors 10 of the phases A, B, C respectively (in nominal mode, G _a = G _b = G _c = 1), and / is the current flowing in the stator windings of the synchronous rotating electrical machine 2.

Differences _of ï ï _q between the measurements and the nominal values are obtained 18 in the landmark Park by equalities:

'd = id, h -' dm

'Q ⁼ ' q, h ^~ 'dm

We have for each of the phases A, B and C:

Paseah

'd (1 -G _a ) / (1 + cos26) (1 -G _a ) / sin26

PhaseB

Phasec

These relationships clearly show that, when a gain defect appears on one of the three phase current sensors 10, a sinusoidal component i _d , _q is added to DC currents i _djh , _h twice the electrical frequency.

The device for diagnosing phase current sensor defects 10 of a control system 1 of a synchronous rotating electrical machine 2 of a motor vehicle, also covered by the invention, is a specific module 25 implementing the described method. above and integrated in the control unit 3 shown in Figure 2.

This specific module 25, according to an architecture known in itself, comprises:

means for acquiring measurements of the phase currents 4, i _b , i _c provided by the sensors 10 and of an electrical angle Θ of the control system 1;

digital processing means for these measurements;

flag generation means Flag_A, B, C 20, 23, 24 signaling the absence or the presence of a fault on one of the sensors 10.

Insofar as the control unit 3 already comprises a microprocessor, a microcontroller or a similar digital circuit, in particular implementing the closed control loop 11, these acquisition means, these digital processing means and these generation means are those of the control unit 3.

A computer code, representative of the method according to the invention, stored in a memory 26, makes it possible to use this common architecture for:

- execute the required Park transformation;

- analyzing waveforms of phase currents in the Park coordinate system;

detect the offset and / or gain defects of the sensors 10;

- identify the faulty sensor.

Flags Flag_A, B, C 20, 23, 24 are taken into account by the closed control loop 1 1 to reconfigure the processing algorithms so as to ensure continuity of operation of the control system 1, even in case of failure of one of the phase current sensors 10.

The method and the device according to the invention are robust thanks to the use of a nonparametric approach independent of an electromechanical model of the machine 2.

It goes without saying that the invention is not limited to the single preferred embodiment described above. Other embodiments are not outside the scope of the present invention insofar as they result from the claims below.

Claims

1) Method for the diagnosis (15, 16) of phase current sensor faults (10) of a control system (1) of a synchronous rotating electrical machine (2) of a motor vehicle, characterized in that said method takes into account differences T _d , T _q between measurements provided (14) by said sensors (10) and nominal values of said phase currents (4 _, i _b , i _c ) in order to diagnose faults if said differences _d ï _q are substantially non-zero (19), said differences i _d, i _q are calculated (18) in a reference frame Park (17) in rotation and being independent of an electromechanical model of said machine (2), a sensor one of said sensors (10) being identified by comparing a measured electrical angle Θ of said control system (1) with a residual electrical angle θ _res defined by the relation:

0, _es = arctan (- T _q / T _d )

where T _d and T _q are the said differences.

2) A method for diagnosing (15, 16) phase current sensor faults (10) of a control system (1) of a synchronous rotary electric machine (2) of a motor vehicle according to claim 1, characterized in that detecting (21, 22) an offset defect of at least one of said sensors (10) if a residual pulse (u) _{res (} s) of said differences (T _d , T _q ) is substantially equal to a measured speed (ω) of said steering system (1). 3) A method for diagnosing (15, 16) phase current sensor faults (10) of a control system (1) of a synchronous rotary electric machine (2) of a motor vehicle according to claim 1, characterized in that detecting (21, 22) a gain defect of at least one of said sensors (10) if a residual pulse of said differences (T _d , T _q ) is substantially equal to twice a speed (ω) measured from said steering system (1).

4) Diagnostic device (25) for phase current sensor defects (10) of a control system (1) of a synchronous rotating electrical machine (2) of motor vehicle adapted to implement the method according to any one of claims 1 to 3 above, of the type comprising:

measurement acquisition means (4, 4, 4) provided by said sensors (10) and an electric angle (Θ) of said control system (1);

digital processing means of said measurements (4, 4, 4);

flag generating means signaling said sensor faults (10); characterized in that said processing means performs Park transformation and includes waveform analysis means of said phase currents (4, 4, 4) in said Park mark (17), said analyzing means of waveforms including means for calculating a moving average over time.

5) Device for diagnosing (25) phase current sensor defects (10) of a control system (1) of a synchronous rotary electric machine (2) of a motor vehicle according to claim 4, characterized in that said acquisition means also acquire a speed (ω) of said control system (1) and in that said processing means further comprise means for detecting an offset defect and / or a defect of gain of at least one of said sensors (10) as a function of said speed (ω).

6) Device for diagnosing (25) phase current sensor faults (10) of a control system (1) of a synchronous rotary electric machine (2) of a motor vehicle according to claim 5, characterized in that said processing means further comprise means for identifying a defective sensor among said sensors (10) as a function of said electric angle (Θ).

7) Synchronous rotating electrical machine (2) comprising at least one integrated control system (1), characterized in that it comprises a diagnostic device (25) for phase current sensor defects of said control system (1) according to any one of the preceding claims 4 to 6.

8) Computer memory (26) for semiconductors for integration in a diagnostic device (25) for phase current sensor faults (10) of a control system (1) of a synchronous rotary electrical machine (2) Motor vehicle according to any one of the preceding claims 4 to 6, characterized in that it contains a computer code representative of the method according to any one of the preceding claims 1 to 3.