Method for controlling an electrical system with a motor

Abstract

Title: Method for controlling an electric motor system Abbreviation: Method for controlling (200) an electric motor system (100), comprising the following steps: measure the rotational speed (201) of the electric motor, calculate a maximum permissible excitation (202) by the electric motor from: the measured rotational speed of the electric motor, a model of the electric motor control the rotational speed (203) of the electric motor by PWM signals whose output excitation is less than the maximum permissible excitation, measure the current (204) through the electric motor, called measured current, make an estimate of the current (205) through the electric motor, called estimated current IEst, from: the measured rotational speed ωmes of the electric motor, the model of the electric motor, update the model (206) of the electric motor from the difference between the measured current IMes and the estimated current IEst.Figure for the abbreviation: Figure 2.

Description

Title of the invention: Method for controlling an electrical system with a motor

[0001] The invention relates to an electrical motor system, and a method for controlling an electrical motor system

[0002] Electronic motors require a protection strategy to limit the electric current. This is necessary to protect the motor's electronics, the motor itself, and the mechanical parts connected to the motor. Currently, in electronic windshield wiper motors, protection based on motor current and motor torque is used. However, this does not offer effective protection because once the current / torque exceeds a certain threshold, the excessive current damages the electronic parts, or the excessive torque damages the mechanical parts, particularly linkages connected to the wiper arms.

[0003] The invention aims to protect the motor electrical system by modeling the electrical operation of the motor to anticipate an increase in current and motor torque, and consequently limit the control signals.

[0004] The invention relates to a method for controlling a motorized electrical system, this motorized electrical system comprising: - an electric motor configured to be powered by several electrical phases, in particular the electric motor being of the three-phase type; - a switching circuit configured to control the supply of electrical phases to the electric motor, this switching circuit comprising switches, in particular of the transistor type, these switches being in particular MOSFETs, - an electronic control unit configured to provide PWM signals to the switches in the switching circuit for control, the method comprising the following steps: - measure the rotational speed co of the electric motor, - Calculate the maximum permissible excitation rmax by the electric motor from: • the measured rotational speed of the electric motor horns, • a model of the electric motor, - control the rotational speed of the electric motor using PWM signals whose output excitation rs is less than the maximum permissible excitation rmax, - measure the current flowing through the electric motor, called the measured current IMes, - to perform an estimate of the current flowing through the electric motor, called the estimated current lEst, based on: • the measured rotational speed of the electric motor horns, • electric motor modeling, - update the electric motor modeling from the difference between the measured current IMes and the estimated current lEst.

[0005] The excitation of a PWM signal is called the duty cycle of the PWM signal.

[0006] According to one aspect of the invention, the rotational speed of the electric motor is directly proportional to the torque exerted by the electric motor.

[0007] According to one aspect of the invention, the rotational speed of the electric motor is directly proportional to the output excitation of the PWM signals applied to the switching circuit of the motor-electric system.

[0008] According to one aspect of the invention, the modeling of the electric motor includes a transfer equation allowing to associate with a rotation speed of the electric motor a maximum permissible excitation rmax corresponding to the maximum permissible torque by the electric motor system.

[0009] According to one aspect of the invention, the modeling of the electric motor includes estimates of operating parameters of the electric motor.

[0010] According to one aspect of the invention, the operating parameters of the electric motor are, for example, the torque constant K of the electric motor and / or the electrical resistance of the armature R.

[0011] According to one aspect of the invention, the operating parameters of the electric motor vary with the operating conditions of the electric motor, in particular with the operating temperature of the electric motor.

[0012] In particular, the torque constant of the electric motor K and / or the electrical resistance of the armature R is dependent on the operating temperature of the electric motor.

[0013] According to one aspect of the invention, the modeling is initialized with initial values ​​of the operating parameters of the electric motor.

[0014] According to one aspect of the invention, the step of updating the modeling of the electric motor includes a step of recalculating the value of at least one operating parameter of the electric motor, in particular using the value of the measured current Imes, in particular using the difference: A = Imes - lest.

[0015] According to one aspect of the invention, the step of updating the modeling of the electric motor includes a step of estimating the operating temperature of the electric motor, in particular using the difference: A = Imes - lest.

[0016] According to one aspect of the invention, the estimation of the current flowing through the electric motor is carried out from the measured rotational speed of the horns and the modeling of the electric motor, and:

[0017] j _

[0018] where J represents the estimated current, V represents the average voltage of the signal PWM at the terminals of the phases of the electric motor, horns represents the measured rotational speed of the electric motor, K represents the torque constant of the electric motor, R the electrical resistance of the armature.

[0019] According to one aspect of the invention, the calculation of the maximum permissible excitation rmax is performed from the measured rotational speed of the electric motor model, and: [00201 = +K* «w

[0021] where Valim represents the supply voltage across the terminals of the electric motor, Tmax represents the maximum permissible torque of the motor electrical system, K represents the torque constant of the electric motor, Im represents the measured current, R the electrical resistance of the armature, and horns represents the rotational speed of the electric motor

[0022] According to one aspect of the invention, the rotation speed is measured periodically, for example every 10 ms.

[0023] According to one aspect of the invention, the rotation speed is evaluated in the last time interval (10 ms).

[0024] According to one aspect of the invention, the method includes the step of evaluating the velocity variation in the following time slot (at +10 ms), taking into account the velocity variation in the previous time slot.

[0025] According to one aspect of the invention, the modeling of the electric motor is updated periodically, in particular at each period of measurement of the rotational speed.

[0026] Alternatively, the modeling of the electric motor is updated every N periods of measurement of the rotational speed, with N > 1.

[0027] The invention makes it possible to use the measurement of the electric motor current to adjust the modeling of the electric motor in order to take into account the evolution of the operating conditions of the electric motor, in particular the evolution of the operating temperature of the electric motor.

[0028] The invention thus makes it possible to improve the accuracy of the calculation of the maximum permissible excitation rmax.

[0029] According to one aspect of the invention, the step of controlling the rotational speed of the electric motor comprises the following steps: - calculate a setpoint excitation rc corresponding to a setpoint rotational speed coc for the electric motor, - to supply the switches of the switching circuit with PWM signals having an output excitation rs such that: rs = min(rc, rmax)

[0030] According to one aspect of the invention, the setpoint excitation rc enabling the setpoint rotation speed coc of the electric motor to be reached is applied as long as it is less than the threshold value rmax.

[0031] According to one aspect of the invention, the step of measuring the current through the electric motor and / or the step of updating the modeling of the electric motor are carried out after the step of calculating the maximum permissible excitation and the step of controlling the rotational speed of the electric motor by PWM signals.

[0032] Measuring the rotational speed of the electric motor advantageously allows estimating the torque exerted by the rotating electrical machine without requiring measurement of the current flowing through the electric motor.

[0033] The invention thus makes it possible to anticipate a risk of malfunction of the electric motor by anticipating the application of too high an excitation at the terminals of the electric motor, which could produce too high a torque.

[0034] Furthermore, the invention is easily implemented and provides robust protection. This allows for a reduction in the weight of the electrical connection and the size of the MOSFET transistors.

[0035] Advantageously, the invention makes it possible to improve the accuracy of the modeling of the electric motor by taking into account the operating temperature of the motor, without requiring the use of a temperature sensor.

[0036] The invention also relates to a motorized electrical system, in particular configured to operate a wiper blade of a vehicle, in particular a motor vehicle, this motorized electrical system comprising: - an electric motor configured to be powered by several electrical phases, in particular the electric motor being of the three-phase type, - a switching circuit configured to control the supply of electrical phases to the electric motor, this switching circuit comprising switches, in particular of the transistor type, these switches being in particular MOSFETs, - an electronic control unit configured to provide PWM signals to the switches of the switching circuit to control them, wherein the electronic control unit is configured to control the motor electrical system according to a method of controlling a motor electrical system as described.

[0037] According to one aspect of the invention, the switching circuit comprises a positive terminal, a negative terminal and a plurality of switching arms mounted in parallel, each arm comprising a top side switch and a bottom side switch connected to each other at a midpoint, each midpoint being intended to be connected to a phase of the electric motor.

[0038] According to one aspect of the invention, the electric motor system includes a current measurement unit arranged to measure the current through the electric motor, called the measured current Imes.

[0039] According to one aspect of the invention, the electric motor system comprises a rotational speed measuring unit arranged to measure the rotational speed of the electric motor's horns

[0040] According to one aspect of the invention, the electric motor is provided with a stator with electromagnetic excitation coils and a rotor with magnets, and is of the brushless type or "brushless" in English, also called a BLDC motor ("Brushless Direct Current").

[0041] According to one aspect of the invention, the switching circuit comprises six MOSFET (or "Metal-Oxide-Semiconductor Field-Effect Transistor") type switches with two transistors for each phase of the electric motor.

[0042] According to one aspect of the invention, the transistors are arranged in an H-bridge configuration and form an inverter.

[0043] According to one aspect of the invention, the electronic control unit includes a microcontroller for controlling power components such as MOSFETs.

[0044] According to one aspect of the invention, the electronic control unit is configured to receive rotation speed instructions for the electric motor and / or data concerning the desired operating mode of this electric motor.

[0045] According to one aspect of the invention, the electrical system is configured to be powered by a DC battery. List of figures

[0046] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0047] [Fig.1] Fig.1 is a representation of an electric motor system according to the invention.

[0048] [Fig.2] Fig.2 is a schematic representation of a method for controlling an electrical motor system according to the invention.

[0049] The features, variants and different embodiments of the invention can be combined with each other in various ways, in provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art. Detailed description

[0050] Figure 1 shows an electrical system 100 with a motor, this electrical system with a motor comprising: - an electric motor 1 configured to be powered by several electrical phases 2, in particular the electric motor being of the three-phase type - a switching circuit 3 configured to control the supply of electrical phases 2 to the electric motor 1, this switching circuit 3 comprising switches 5, in particular of transistor type, these switches being in particular MOSFETs, - an electronic control unit 6 configured to supply PWM signals to the switches 5 of the switching circuit 3 for control.

[0051] The PWM signal transmission lines are symbolized by the lines 17 in [Fig. 1]

[0052] The electric motor system 100 is configured to operate a wiper brush of a vehicle, in particular a motor vehicle, not shown in the figure.

[0053] The electronic control unit 6 is configured to control the motor-driven electrical system 100 according to a method of controlling a motor-driven electrical system 200 as described in [Fig.2].

[0054] The electric motor system 100 includes a current measuring unit 10 arranged to measure the current through the electric motor 1, called the measured current Imes.

[0055] The electric motor system 100 includes a rotation speed measuring unit 11 arranged to measure the rotation speed of the electric motor horns 1.

[0056] The electric motor 1 is provided with a stator with electromagnetic excitation coils and a rotor with magnets, and is of the brushless type or "brushless" in English, also called a BLDC motor ("Brushless Direct Current").

[0057] The switching circuit 3 comprises a positive terminal, a negative terminal and a plurality of switching arms mounted in parallel, each arm comprising a top side switch and a bottom side switch connected to each other at a midpoint, each midpoint being intended to be connected to a phase of the electric motor.

[0058] The switching circuit comprises six MOSFET type switches 5 (or "Metal-Oxide-Semiconductor Field-Effect Transistor") with two transistors for each phase 2 of the electric motor 1.

[0059] The transistors 5 are arranged in an H-bridge configuration and form an inverter.

[0060] The electronic control unit 6 includes a microcontroller for controlling power components such as MOSFETs.

[0061] The electronic control unit 6 is configured to receive rotation speed commands for the electric motor 1 and / or data concerning the desired operating mode of this electric motor.

[0062] The electrical system 100 is configured to be powered by a DC battery, not shown in the figure.

[0063] Figure 2 shows a method 200 for controlling an electrical system 100 with a motor according to the invention.

[0064] The control method 200 comprises the following steps: - measure the rotational speed 201 of the electric motor 1, - Calculate the maximum permissible excitation rmax 202 by the electric motor from: • the rotational speed of electric motor 1, • a model of electric motor 1, - control the rotation speed 203 of the electric motor by signals PWM whose output excitation rs is less than the maximum permissible excitation rmax, - measure the current 204 flowing through the electric motor 1, called measured current IMes. - to perform an estimate 205 of the current flowing through the electric motor, called estimated current lEast, from: • the rotational speed of electric motor 1, • Electric motor modeling - update the 206 model of the electric motor from the difference between the measured current IMes and the estimated current lEst.

[0065] The excitation of a PWM signal is called the duty cycle of the PWM signal.

[0066] The rotational speed of the electric motor 1 is directly proportional to the torque exerted by the electric motor 1 and at the output excitation of the PWM signals applied to the motor-driven electrical system switching circuit.

[0067] The modeling of the electric motor includes a transfer equation allowing to associate to a rotation speed of the electric motor 1 a maximum permissible excitation rmax corresponding to the maximum permissible torque by the electrical system 100 with motor.

[0068] The modeling of the electric motor 1 includes estimates of operating parameters of the electric motor 1, for example the torque constant K of the electric motor and / or the electrical resistance of the armature R

[0069] These operating parameters of the electric motor 1 vary with the operating conditions of the electric motor, in particular with the operating temperature of the electric motor 1. In particular, the torque constant of the electric motor K and / or the electrical resistance of the armature R is dependent on the operating temperature of the electric motor 1.

[0070] The model is initialized with initial values ​​of the operating parameters of the electric motor 1.

[0071] The update step 206 of the electric motor modeling includes a recalculation step 207 of the values ​​of the operating parameters of the electric motor 1, in particular using the value of the measured current IMes, in particular using the difference: A = IMes - lEst.

[0072] The step of updating the modeling of the electric motor includes a step of estimating the operating temperature 208 of the electric motor, in particular using the difference: A = IMes - lEst.

[0073] The estimation of the current 5 flowing through the electric motor is carried out from the measured rotational speed and the modeling of the electric motor, and:

[0074] j _

[0075] where lEst represents the estimated current, V represents the average voltage of the PWM signal across the phases of the electric motor, cornes represents the rotational speed of the electric motor, K represents the torque constant of the electric motor, and R the electrical resistance of the armature.

[0076] The calculation of the maximum permissible excitation rmax is performed from the measured rotational speed of the electric motor model, and:

[0077]

[0078] where Valim represents the supply voltage across the terminals of the electric motor, Tmax represents the maximum permissible torque of the motor-electric system, K represents the torque constant of the electric motor, Im represents the measured current, R the electrical resistance of the armature, and horns represents the measured rotational speed of the electric motor. The rotational speed is measured periodically, for example every 10 ms.

[0079] The rotational speed is evaluated in the last time interval (10 ms), and the method includes the step of evaluating the speed variation in the time slot. following (at +10 ms), taking into account the speed variation in the previous time slot.

[0080] The modeling of the electric motor 1 is updated periodically, in particular at each period of measurement of the rotational speed.

[0081] Alternatively, the modeling of the electric motor is updated every N periods of measurement of the rotational speed, with N > 1.

[0082] The invention makes it possible to use the measurement of the electric motor current 204 to adjust the electric motor modeling so as to take into account the evolution of the electric motor's operating conditions, in particular the evolution of the electric motor's operating temperature. The invention thus makes it possible to improve the accuracy of the calculation of the maximum permissible excitation rmax 202.

[0083] The step of controlling the rotational speed 203 of the electric motor 1 comprises the following steps: - calculate a setpoint excitation rc 209 corresponding to a setpoint rotational speed coc for the electric motor, - to supply the switches of the electronic control unit 210 with PWM signals having an output excitation rs such that: rs = min(rc, rmax)

[0084] The setpoint excitation rc enabling the setpoint rotation speed of the electric motor to be reached is applied as long as it is less than the threshold value rmax.

[0085] The current measurement step 204 through the electric motor 1 and the electric motor modeling update step 206 are carried out after the maximum permissible excitation calculation step 202 and the electric motor rotation speed control step 203 by PWM signals.

[0086] Measuring the rotational speed 201 of the electric motor advantageously allows estimating the torque exerted by the rotating electrical machine without requiring measurement of the current flowing through the electric motor.

[0087] The invention thus makes it possible to anticipate a risk of malfunction of the electric motor by anticipating the application of too high an excitation at the terminals of the electric motor, which could produce too high a torque.

[0088] Furthermore, the invention is easily implemented and provides robust protection. This allows for a reduction in the weight of the electrical connection and the size of the MOSFET transistors.

[0089] Advantageously, the invention makes it possible to improve the accuracy of the modeling of the electric motor by taking into account the operating temperature of the motor, without requiring the use of a temperature sensor.

Claims

Demands

1. A method for controlling (200) an electric motor system (100), this electric motor system comprising: - an electric motor (1) configured to be supplied by several electrical phases (2), in particular the electric motor being of the three-phase type; - a switching circuit (3) configured to control the supply of the electrical phases (2) to the electric motor, this switching circuit comprising switches (5), in particular of the transistor type, these switches being in particular MOSFETs, - an electronic control unit (6) configured to provide PWM signals to the switches (5) of the switching circuit (6) for control, the method (200) comprising the following steps: - measuring the rotational speed co (201) of the electric motor (1), - calculating a maximum permissible excitation rmax (202) by the electric motor from: • the measured rotational speed of the electric motor (1),• from a model of the electric motor (1), - control the rotational speed (203) of the electric motor (1) by PWM signals whose output excitation rs is less than the maximum permissible excitation rmax, - measure the current (204) flowing through the electric motor (1), called the measured current IMes, - perform an estimation of the current (205) flowing through the electric motor, called the estimated current lEst, from: • the measured rotational speed of the electric motor, • the model of the electric motor, - update the modeling (206) of the electric motor from the difference between the measured current IMes and the estimated current lEst.

2. Control method (200) according to claim 1, wherein the modeling of the electric motor includes a transfer equation allowing to associate to a rotation speed of the electric motor (1) a maximum permissible excitation rmax corresponding to the maximum permissible torque by the electric motor system (100).

3. A control method (200) according to any one of the preceding claims, wherein the modeling of the electric motor (1) includes estimates of operating parameters of the electric motor (1), in particular the torque constant K of the electric motor and / or the electrical resistance of the armature R.

4. Control method (200) according to claim 3, wherein the step of updating the modeling (206) of the electric motor (1) includes a step of recalculating (7) the value of at least one of the operating parameters of the electric motor (1), in particular using the value of the measured current Imes, in particular using the difference: A = Imes - lest.

5. Control method (200) according to any one of claims 3 to 4, wherein the estimation of the current through the electric motor is carried out from the measured rotational speed and the modeling of the electric motor (1).

6. Control method (200) according to any one of the preceding claims, wherein the step of updating the modeling (206) of the electric motor (1) includes a step of estimating the operating temperature (208) of the electric motor, in particular using the difference: A = Imes - lest.

7. A control method (200) according to any one of the preceding claims, wherein the rotational speed of the electric motor (1) is measured periodically, for example every 10 ms.

8. A control method (200) according to any one of the preceding claims, wherein the step of controlling the rotational speed (203) of the electric motor (1) comprises the following steps: - calculate a setpoint excitation rc (209) corresponding to a setpoint rotation speed coc for the electric motor, - supply the switches of the switching circuit with PWM signals (210) having an output excitation rs such that: rs = min(rc, rmax).

9. Control method (200) according to the preceding claims, wherein the step of measuring the current (204) through the electric motor and / or the step of updating the modeling (206) of the electric motor are carried out after the step of calculating the maximum permissible excitation (202) and the step of controlling the rotational speed (203) of the electric motor (1) by PWM signals.

10. A motorized electrical system (100), in particular configured to operate a wiper brush of a vehicle, in particular of a motor vehicle, said motorized electrical system comprising: - an electric motor (1) configured to be supplied by several electrical phases (2), in particular the electric motor being of the three-phase type; - a switching circuit (3) configured to control the supply of the electrical phases (2) to the electric motor (1), this switching circuit comprising switches (5), in particular of the transistor type, these switches being in particular MOSFETs, - an electronic control unit (6) configured to provide PWM signals to the switches (5) of the switching circuit (3) for control, in which the electronic control unit (6) is configured to control the motorized electrical system (100) according to a control method according to any one of the preceding claims.

11. Electric motor system (100) according to claim 10, comprising a current measuring unit (10) arranged to measure the current through the electric motor (1), referred to as measured current Imes.

12. Motorized electrical system (100) according to any one of claims 10 to 11, the motorized electrical system (100) comprising a unit of rotation speed measurement (11) arranged to measure the rotation speed of the horns of the electric motor (1).

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