Electromechanical actuator comprising an electric motor without sensors; closing system comprising such an electromechanical actuator

Abstract

Electromechanical actuator comprising an electric motor without sensors, closing system comprising such an electromechanical actuator. This electromechanical actuator (4) for a closing system comprises a synchronous, electronically commutated, permanent magnet electric motor (11) without angular position sensors. An electronic control device is configured to: • supply power to the motor when it is in a stopped position, • automatically estimate the angular position of the rotor using the determining means, • automatically control the motor taking into account the estimated angular position. A mechanical brake coupled to a motor output is configured to, when starting the motor from the stopped position, allow the motor to rotate by temporarily preventing the load from exerting torque on the motor for a brake release period adapted to the predefined period. Figure for the abbreviation: 1.

Description

Title of the invention: Electromechanical actuator comprising an electric motor without sensors, closing installation comprising such an electromechanical actuator

[0001] The present invention relates to an electromechanical actuator, in particular for a closing, occultation or solar protection installation, in particular for a building, as well as a closing, occultation or solar protection installation comprising a movable screen, in particular rollable on a winding tube driven in rotation, by such an electromechanical actuator. The present invention relates to a method for controlling an electromechanical actuator.

[0002] Generally, the present invention relates to the field of occultation devices comprising a motorized drive device moving a screen, between at least a first position and at least a second position.

[0003] A motorized drive device within the meaning of the present application may comprise an electromechanical actuator of a mobile closing, concealing or solar protection element such as a shutter, a door, a grille, a blind or any other equivalent material, hereinafter called a screen.

[0004] The invention is applicable to electromechanical actuators comprising an electronically commutated brushless electric motor, also called "BLDC" (acronym for the term "BrushLess Direct Current") or more generally a permanent magnet synchronous electric motor, also called "PMSM" (acronym for the term "Permanent Magnetic Synchronous Motor").

[0005] The invention is more particularly applicable to the case where these electric motors are devoid of position sensors.

[0006] Indeed, to control a BLDC motor or a PMSM motor, it is necessary to know at all times the angular position of the rotor of the electric motor, in order to send the correct control sequence and to excite the motor windings adequately to obtain the desired operation.

[0007] However, in many applications, it is preferable not to use dedicated sensors (such as Hall effect sensors or encoder wheels), for various reasons, including because these sensors have a large footprint and complicate the design and manufacture of the actuator. The use of sensors requires tight positioning tolerances to achieve optimal performance.

[0008] Instead of using a sensor, the angular position of the rotor can be estimated indirectly by means of electrical quantities associated with the motor, for example by the measurement of electrical voltages between terminals of the windings. For example, the angular position of the rotor can be estimated by detecting an image of the zero crossing of the motor's counter-electromotive force for one of the motor's terminals at the moment when there is no electrical current on this terminal. A control strategy is therefore put in place from the measured information, generally using an electronic controller which analyzes the measured electrical quantities.

[0009] There are many strategies for driving such motors while estimating the rotor position without using sensors.

[0010] A problem may arise, however, when starting the motor. In electric motors provided with angular position sensors, the position sensors generally remain active when the motor is stopped, or are restarted before the motor is started, so that the angular position of the rotor is known precisely when the motor restarts. This is not possible in motors without position sensors.

[0011] In practice, in motors without position sensors, known solutions for estimating the angular position of the motor more or less roughly approximate an angular position at start-up. An imprecise estimation of the angular position can be tolerated in applications for which the motor must develop a low torque at start-up, typically when the mechanical load driven by the motor is light and does not require a large torque to be moved. Examples include applications such as model making, electric bicycles, domestic fans, and many other examples. Moreover, in these applications, the motor is generally not designed to start by exerting a nominal torque. On the contrary, the exerted torque increases slowly as the motor starts.

[0012] However, these control strategies do not work satisfactorily when the motor must provide a high torque at start-up, as is the case, for example, in a domestic closing installation, in which the electrical load may be a screen, or a shutter, or a blind, the mass of which is generally greater than one or several kilograms or several tens of kilograms, and for which the torque to be exerted at start-up of the motor is generally greater than or equal to the nominal torque, of the order of several Nm. For example, these may be torques ranging from 6 to 10 Nm, or even up to 50 Nm.

[0013] There is thus a risk that the estimation of the position is affected by errors, or even that the motor does not start when it is coupled to a load such as a screen in a closing installation.

[0014] It is these drawbacks that the invention more particularly intends to remedy by proposing an electromechanical actuator, in particular for an installation of closing, concealment or solar protection, in particular for a building, comprising a permanent magnet synchronous electric motor without electronically commutated sensors.

[0015] To this end, one aspect of the invention relates to an electromechanical actuator for a closing, occulting or solar protection installation, the electromechanical actuator comprising an electric motor, a mechanical brake coupled to an output of the motor and an electronic control device configured to drive the motor, the motor being a synchronous electric motor with permanent magnets and electronic commutation, the motor being devoid of angular position sensors associated with the rotor, the actuator comprising means for determining the angular position of the rotor from electrical quantities measured between power supply terminals of the motor, the electronic control device being configured to implement steps consisting of:

[0016] • power the motor while it is in a stopped position,

[0017] • automatically estimate the angular position of the rotor with the means of determining mination,

[0018] • automatically control the motor taking into account the angular position estimated,

[0019] the steps being performed over a predefined period corresponding to the motor traveling through a predefined interval of angular positions from the stop position, the brake being configured to, upon starting the motor from the stop position, allow rotation of the motor by temporarily preventing the load from exerting torque on the motor during a brake release period adapted to the predefined period.

[0020] According to advantageous but not obligatory aspects, such an actuator may incorporate one or more of the following characteristics, taken in isolation or in any technically admissible combination:

[0021] - the brake is a mechanical spring brake.

[0022] - The brake release period is adjustable by adapting the diameter of a coil spring of the spring brake or by adapting the diameter of a metal wire forming a coil spring of the spring brake.

[0023] - The brake release period is adjustable by adapting characteristics of a reducer connected to the motor output, between the brake and the motor output.

[0024] - The electronic control device is configured to drive the motor with a trapezoidal control law, the brake being configured to, upon starting the motor from the stop position, allow rotation of the motor by temporarily preventing the load from exerting torque on the motor for a brake release period at least equal to the predefined period.

[0025] - The electronic control device is configured to drive the motor with a sinusoidal control law, the brake being configured to, upon starting the motor from the stop position, allow rotation of the motor by temporarily preventing the load from exerting torque on the motor for a brake release period greater than the predefined period.

[0026] According to another aspect, the invention relates to a closing, concealing or solar protection installation, comprising a screen and an electromechanical actuator configured to drive the screen in movement, in which the electromechanical actuator is as previously described.

[0027] According to another aspect, the invention relates to a method for controlling an electromechanical actuator for a closing, occulting or solar protection installation, the electromechanical actuator comprising an electric motor, a mechanical brake coupled to an output of the motor and an electronic control device configured to control the electric motor, the electric motor being a synchronous electric motor with permanent magnets and electronic commutation, the actuator comprising means for determining the angular position of the rotor from electrical quantities measured between power supply terminals of the motor, the method comprising steps consisting of:

[0028] • start the engine from a stop position,

[0029] • automatically estimate the angular position of the rotor with the means of determining mination,

[0030] • automatically control the motor taking into account the angular position estimated,

[0031] the steps being carried out over a predefined period corresponding to the motor traveling through a predefined interval of angular positions from the stop position, the method being such that, when starting the motor from the stop position, the brake allows the motor to rotate by temporarily preventing the load from exerting torque on the motor for a period adapted to the predefined period.

[0032] According to advantageous but not mandatory aspects, such a method may incorporate one or more of the following characteristics, taken in isolation or in any technically admissible combination:

[0033] - the motor is controlled with a trapezoidal control law, the brake authorizing, during starting the motor from the stop position, rotating the motor by temporarily preventing the load from exerting torque on the motor for a brake release period at least equal to the predefined period.

[0034] - The motor is controlled with a sinusoidal control law, the brake being configured to, when starting the engine from the stop position, allow the engine to rotate by temporarily preventing the load from exerting torque on the engine for a brake release period longer than the predefined period.

[0035] The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an embodiment, given solely by way of example and with reference to the appended drawings, in which:

[0036] - [Fig.l] [Fig.l] schematically represents a home automation installation comprising an electromechanical actuator according to embodiments of the invention, the electromechanical actuator being mechanically coupled to a mechanical load;

[0037] - [Fig.2] [Fig.2] schematically represents an electric motor belonging to the electromechanical actuator of [Fig.l];

[0038] - [Fig.3] [Fig.3] schematically represents an example of a mechanical brake with friction of the electromechanical actuator of [Fig.l];

[0039] - [Fig.4] [Fig.4] schematically represents a method of controlling the actuator of [Fig.l] according to embodiments of the invention;

[0040] - [Fig.5] [Fig.5] schematically represents the effects of a friction brake mechanical acting on the electromechanical actuator of [Fig.l] in accordance with the invention when the mechanical load driven by the electromechanical actuator is moved in an upward direction, and

[0041] - [Fig.6] [Fig.6] schematically represents the effects of a friction brake mechanical acting on the electromechanical actuator of [Fig.l] according to the invention when the mechanical load driven by the electromechanical actuator is moved in a downward direction.

[0042] Figures 1 and 2 illustrate a home automation installation 1 installed in a building comprising an opening 3, such as a window or a door.

[0043] The installation 1 comprises a home automation device for occultation, or solar protection, or closing and / or protection, and for this purpose comprises a mobile load 2 such as a screen.

[0044] The mobile load 2, or screen, is for example configured to obscure the opening 3 formed in the building.

[0045] According to examples listed in a non-limiting manner, the screen 2 can be a roller shutter, or a metal curtain, or a blind, such as a fabric blind, or one with adjustable slats, or a garage door, or even a rolling gate, or other examples of a concealment device.

[0046] In the following description, the screen 2 is a roller shutter. This example is not limiting. The description given below of the actuator and its operation can be transposed to other home automation installations in which the load 2 is carried out differently.

[0047] The screen 2 is movable between an open position and a closed position (or even, for example, into one or more stable intermediate positions), here by sliding in rails mounted on uprights 6 arranged on either side of the opening 3.

[0048] The installation 1 comprises an electromechanical actuator 4 comprising an electric motor 11, for example fixed to a wall or a wall support of the building.

[0049] The screen 2 is mechanically coupled to the actuator 4.

[0050] Preferably, the screen 2 is configured to be wound onto a winding tube 5 driven by the actuator 4, here by means of fasteners 10 which mechanically connect the screen 2 to the winding tube 5.

[0051] The winding tube 5, as well as the actuator 4, can be housed in a box 9 fixed to the building. The box 9 is for example arranged above the opening 3, or in the upper part of the opening 3. For example, the winding tube 5 extends along a longitudinal axis here bearing the reference “X”. Pivot connections allow the winding tube and the actuator 4 to rotate around the longitudinal axis X.

[0052] In some examples, the actuator 4 may be inserted into the winding tube 5, for example during assembly of the occulting device.

[0053] The actuator 4 is controlled by a control device.

[0054] The control device is here schematically illustrated in a location 15 inside the winding tube 5, but in practice the control device can be arranged elsewhere, for example inside the box 9, or in a casing of the electromechanical actuator 4.

[0055] As shown in [Fig. 2], the control device, which here bears the reference numeral 20, comprises a power supply circuit 22 and an electronic control unit 24, which are described in more detail in the following.

[0056] The motor 11 comprises a rotor 26 and a stator 28. The rotor 26 is for example mechanically connected to the winding tube 5. On the stator 28, coils 30, or windings 30, are mounted, electrically powered by power supply lines 34 connected to the power supply circuit 22. For example, the coils 30 are connected in a triangle or “delta” configuration, this example not being limiting.

[0057] For the purposes of the present description, a rotation of the motor 11 designates a rotation of the rotor 26 relative to the stator 28 of the motor 11. The two expressions may be used interchangeably in the following. Similarly, the expressions “position of the motor” and “angular position of the motor” refer to the angular position of the rotor 26 relative to the stator 28.

[0058] In preferred embodiments, the motor 11 is an electric motor with brushless direct current and electronically commutated (BLDC). More generally, the motor 11 is a permanent magnet synchronous electric motor (PMSM).

[0059] The motor 11 is devoid of angular position sensors associated with the rotor of the motor. In other words, the motor 11 is a sensorless motor.

[0060] As will be understood from reading the description, the angular position of the rotor 26 is estimated automatically from measurements of electrical quantities, for example by means of electrical voltages between power supply terminals of the motor 11 (connected to the windings 30). In other words, the actuator comprises means for determining the angular position of the rotor from electrical quantities measured between power supply terminals of the motor. Said means are preferably electronic means, implemented by the control unit 24.

[0061] For example, the angular position of the rotor can be estimated by detecting an image of the zero crossing of the motor's back-electromotive force for one of the motor's terminals at the time when there is no electric current on that terminal.

[0062] The power supply circuit 22 is powered by an energy source 36, such as a battery or an electrical power supply network to which the circuit 22 is connected by electrical connectors 38, 40. The power supply received may be a direct or alternating electrical voltage, preferably single-phase or even three-phase.

[0063] The circuit 22 comprises an input stage 42 and a power converter 44.

[0064] The input stage 42 is connected downstream of the connectors 38, 40 and may comprise means for conditioning the received electrical voltage, such as a filter, or a rectifier, or an electrical protection device, or any suitable element or any combination of such elements. The power converter 44 is connected downstream of the stage 42 and may comprise a DC-AC converter or chopper. For example, the power converter 44 comprises power switches, such as transistors, electronically controlled by the control unit 24.

[0065] The control unit 24 is configured to drive the motor 11 so as to set the screen 2 in motion to move it to a desired position. In other words, the motor 11 is an electronically commutated motor.

[0066] For example, the control unit 24 is configured to drive the motor 11 using a pulse width modulation (or PWM) technique.

[0067] Preferably, the control unit 24 is also configured to estimate the angular position of the rotor of the actuator 4, for example from the voltages measured between the supply lines 34 and / or between the supply terminals of the motor.

[0068] In some examples, the controller is further configured to control the motor 11 taking into account the estimated angular position of the rotor 26. For example, in this control mode, also called “autopilot” mode, unlike open-loop operation, the control signal sent to the motor is determined taking into account the estimated (or measured) position of the rotor.

[0069] For example, the control unit 24 comprises an electronic control circuit 46 comprising a processor 48 and a memory 50. For example, the processor 48 is a programmable microcontroller or a microprocessor.

[0070] The memory 50 is for example a computer memory forming a computer-readable data recording medium. According to examples, the memory 50 comprises a read-only ROM memory, or a RAM memory, or a non-volatile memory of the EEPROM, or FLASH, or NVRAM type, or an optical memory or a magnetic memory, or any suitable memory technology or any combination of such elements. The memory 50 comprises executable instructions and / or software code for implementing a method for controlling the actuator 4 when these instructions are executed by the logic calculation unit.

[0071] The use of the term "processor" does not prevent, as a variant, at least part of the functions from being performed by other electronic components, such as a signal processing processor (DSP), or a reprogrammable logic component (FPGA), or a specialized integrated circuit (ASIC), or any equivalent element, or any combination of these elements.

[0072] The control circuit 46 may also comprise an input interface 52 configured to receive measurement signals, for example to collect signals representative of the voltages measured between the power supply terminals of the motor 11. For example, the power supply lines 34 are connected to the input interface 52 by measurement probes. For example, the interface 52 comprises an analog-to-digital converter, or a filter, or an amplifier, or any suitable element or combination of these elements.

[0073] The control circuit 46 may comprise a signal output interface 54, for example for emitting control signals to control the power switches of the power converter 44 according to orders emitted by the processor 48.

[0074] The control device 20 may comprise an order reception input 52 configured to receive position instructions and / or movement orders (for example opening or closing the screen 2) coming from a control device 12, such as a switch, or from a mobile communication device 13, or from a remote control 14, or from a computer, or from a home automation center, and many other examples.

[0075] For example, the command reception input 52 is connected to the power supply terminals of the motor 11 or to the power supply lines 34, to take a electrical voltage between these terminals, and in particular to measure an electrical quantity between these terminals.

[0076] Particularly advantageously, the actuator 4 comprises a braking system 16 configured to exert a braking torque on the motor 11. The braking system 16 is also called “brake” in the following.

[0077] Preferably, the braking system 16 is a mechanical friction brake, such as a spring brake.

[0078] According to an exemplary implementation, as illustrated in the example of [Fig. 3], the brake 16 comprises a helical spring 161 whose turns 162 are centered on a longitudinal axis X16 of the braking system. The helical spring 161 is configured to exert a force on a friction part 163. Preferably, the brake 16 is mounted concentrically with the rest of the actuator, for example by being coaxial with the rotor of the motor 11 or with an output shaft 164 mechanically secured to the rotor of the motor 11. For example, when the brake 16 is mounted in the actuator 4, the longitudinal axis X16 of the brake 16 coincides with the longitudinal axis X of the actuator 4. For example, the helical spring is housed in a drum 165 of the brake.

[0079] The opposite ends 166, 167 of the wire 162 forming the helical spring 161 are shaped so as to be able to be moved by the rotation of the motor 11 or by the load 2, so as to compress the spring or on the contrary to relax the spring 161, which makes it possible respectively to increase or reduce the braking force exerted by the brake 16.

[0080] For example, each of the opposite ends 166, 167 of the wire 162 forming the helical spring 161 comprises a tab, this tab being able to form a stop for the rotation of a moving part 164 coupled to an output of the motor 11, and / or of another moving part 163 coupled to the load 2 driven by the actuator 4.

[0081] Preferably, the brake 16 is placed at the output of the motor 11, for example at the output of a reducer placed at the output of the motor 11, the reducer being mechanically coupled to the rotor 26, possibly via an output shaft of the motor 11. Preferably, the brake 16 is placed at the output of a first stage of the reducer if the latter comprises several reduction stages.

[0082] Examples of construction of such a spring brake are described, among others, in document WO 2014 / 037366 A1 and in document FR 2610668 B. Other embodiments can nevertheless be used.

[0083] One aspect of the invention consists in using a mechanical friction brake 16 in the actuator 4 in conjunction with the motor 11 and characterizing the brake 16 to facilitate the control of the electronic commutation of the motor 11. By characterizing, it is meant for example that characteristics of the brake 16 are adapted, and / or that the manner in which the brake and the control cooperate is adapted.

[0084] In particular, the brake 16 is configured so that the rotor can rotate freely at start-up, for a suitable predefined duration, such as a switching period (in the case where the control signal sent to the motor is switched periodically) of the motor 11. In other words, the load 2 is temporarily decoupled from the rotor 26 at start-up of the motor: the rotor rotates without load, and this for a predefined angular displacement range.

[0085] This predefined duration may be called “unlocking period” in the following.

[0086] Preferably, during this time, the load 2 is held stationary 2 and is not driven by the motor 11, and no torque is exerted by the load 2 on the rotor 26 of the motor 11. In the case of a spring brake, the release angle of the spring brake can be adapted so that the brake releases the rotor during a certain range of angular movement at start-up. In other words, the brake is characterized by adapting the release angle to the desired range of free angular movement of the rotor at start-up.

[0087] Thus, if the motor can rotate freely at start-up over a minimum angular range, it is possible for the control device 20 to determine the angular position of the rotor 26 at start-up of the actuator 4 during this angular movement and thus to calibrate the angular position of the rotor 26 for the rest of the method of controlling the motor 11. For example, the position information determined by the control device 20 during the free angular movement range of the rotor is used to adjust the command sent when the load appears at the end of the free angular movement range.

[0088] For example, when the commutation of the motor 11 is controlled by the control device 20 with a trapezoidal control law, then the brake 16 is configured to, when starting the motor from the stop position, allow the rotation of the motor by temporarily preventing the load from exerting a torque on the motor during a brake unlocking period at least equal to the predefined period. For example, the motor control is modified periodically with an angular periodicity of 60°. In this case, the spring brake 16 must have an unlocking angle of at least 60°. In other words, the brake 16 is configured to allow free movement of the rotor 26 of the motor at least during the first operating range of 60°.

[0089] And, in the case where the electronic control device 20 is configured to control the motor with a sinusoidal control law, the brake 16 being configured to, when starting the motor from the stop position, authorize the rotation of the motor by temporarily preventing the load from exerting a torque on the motor during a brake unlocking period greater than the predefined period.

[0090] In practice, the spring release angle depends on the torque required to release the spring.

[0091] For example, when the motor 11 stops being powered after having been set in motion in a first direction of rotation, the rotor 26 stops rotating and stops driving the second leg 167 of the spring 161, which leads to a return of the coils of the spring to a braking position. The first end 166 of the helical spring which is in interaction with the mechanical load 2 (for example by means of the corresponding first leg) is in fact blocked relative to the second end. This leads to an immobilization of the load 2. The second end 167 of the helical spring, which is associated with the output of the motor 11 and therefore, directly or indirectly, in interaction with the rotor 26, is at this stage subjected to the mechanical force caused by the tension of the helical spring.Once the load is blocked, this second end of the spring (or second leg of the spring) will therefore move to return to the rest position of the helical spring 161: this is the drag return. This return rotational movement is made in a second direction of rotation which is opposite to the first direction of rotation. The angle traveled by the rotor in this return movement corresponds to the unlocking angle of the spring. This return movement continues until reaching a rotor stop position.

[0092] When the motor 11 is powered again to be put back into motion in a chosen direction of rotation (whether the previous direction of rotation or the opposite direction of rotation) from the stop position, the rotational movement of the rotor 26 drives the second end of the spring 167 (the second leg) into rotation. In a first phase of the movement, the second end of the spring travels, in the chosen direction of rotation, the interval of angular positions corresponding to the unlocking angle. At this stage, the load 2 is still immobilized by the brake spring and it therefore does not exert any mechanical torque on the rotor 26. Thus, the rotation of the motor 11 is not hindered by the load 2. It is during this range of movement that the detection method is advantageously implemented to estimate the position of the rotor 26 at start-up.

[0093] Once, due to the rotation of the rotor 26, the second end of the spring has traveled through the interval of angular positions corresponding to the unlocking angle, which corresponds to a catch-up of the unlocking angle, then, in a second phase of the movement, the coils of the spring are released from their braking position and the first end of the spring begins to move in the same direction, thus releasing the mechanical load 2. The load 2 can then exert a resistive torque on the rotor 26.

[0094] The example has been described with reference to a spring brake, but other mechanical friction brakes exhibiting similar behavior can be used in variant. Generally speaking, the term "unlocking angle" defines the length of the predefined interval of angular positions for which, when the motor is started, the brake 16 allows the rotor 26 to rotate freely without being subjected to any torque exerted by the load 2, regardless of the mechanical brake technology 16 used.

[0095] This behavior is also guaranteed regardless of the direction of rotation corresponding to the first direction of rotation (clockwise or counterclockwise) leading either to a movement in driving load or in driven load.

[0096] In practice, the unlocking angle of the brake 16 can be adjusted, in the case of a spring brake, by adjusting the dimensioning of the spring, for example by adapting one or more characteristics such as the diameter of the metal wire forming the helical spring, or the outside diameter or the inside diameter of the spirals formed by the winding of the helical spring.

[0097] Depending on the architecture of the spring brake, the clamping radius of the coil spring on the brake drum or on a drive shaft (around which the spring is mounted) can also be used as an adjustable characteristic.

[0098] For example, a clamping radius of between 0.1 mm and 0.2 mm can be chosen, the clamping radius being defined as the difference between the outer radius of the spiral formed by the winding of the helical spring of the spring brake 16 and the inner radius of the drum in which the spring is housed.

[0099] According to other embodiments, the unlocking angle can be adjusted according to characteristics of a reducer connected to the output of the motor, between the brake 16 and the output of the motor 11. For example, the first stage of the reducer makes it possible to amplify the unlocking angle of the brake by multiplying it by the reduction ratio of the first stage. The intrinsic elasticity of the reducer could also be taken into account.

[0100] Preferably, the value of the unlocking angle is chosen as a function of the shape of the control signal and / or the waveform of the electrical voltage used to power the motor.

[0101] For example, as explained previously, in the case of a trapezoidal control, having a periodicity of 60°, an unlocking angle at least equal to 60° is used, or equal to 60° to within plus or minus 10% or to within plus or minus 5%.

[0102] In the case of sinusoidal control, an angle value of less than 60° may be preferred, because as the motor must then be controlled in open loop, and this results in high energy consumption, it is preferable to reduce the corresponding duration.

[0103] Examples of operation of the actuator 4 and of the control device 20 are now illustrated with reference in particular to the diagram of [Fig. 3] and with the aid of figures 4 and 5.

[0104] [Fig.3] shows an example of operation of actuator 4 when actuator 4 starts while connected to a mechanical load such as load 2.

[0105] The method starts during a step 100, during which the actuator 4 is put into operation from a stop position.

[0106] For example, the motor 11 is initially stopped, for example after having been previously moved. Before the actuator is started, the motor 11 is not driven and the load 2 is stationary.

[0107] During a step 102, the control device 20 automatically develops and sends a control signal to drive the motor 11, for example according to a predefined control law, by means of the control unit 24. Electrical voltages are then applied to the power supply terminals of the motor 11, thanks to the power supply circuit 22, to electrically power the coils 30 and thus rotate the rotor 26 of the motor 11 according to the defined control signals.

[0108] During a step 104, once the motor 11 begins to rotate, the control device 20 automatically estimates the position of the rotor 26 of the motor 11, from electrical quantities measured between power supply terminals of the motor 11, for example at the terminals of the coils 30 or between the electrical power supply lines 34. Preferably, the measured electrical quantities are representative of the electromotive forces present between the power supply terminals of the motor 11, for example between the terminals of the coils 30.

[0109] During this step 104, thanks to the configuration of the brake 16, the rotor 26 is capable of moving, for a suitable limited duration, corresponding to the first phase of the movement defined above, that is to say freely relative to the load 2. For example, for this interval of angular positions corresponding to the unlocking angle, the brake 16 as characterized prevents the load 2 from exerting a torque on the rotor and allows free rotation of the rotor 26.

[0110] Because the motor can rotate freely at startup, the position of the rotor can be accurately estimated without the need to use position sensors. Furthermore, since this inhibition of braking is only temporary, it does not prevent the brake from playing its role in the operation of the actuator 4.

[0111] This determination of the angular position at start-up is important because it conditions the precision of the estimation of the position for the remainder of the movement of the motor, in particular it conditions the estimation of the position at the start of the movement of the load.

[0112] During a step 106, the control device 20 automatically develops and sends a control signal to drive the motor 11 at the start of the second movement phase, for example according to a predefined control law, by means of the control unit 24, taking into account the estimated position of the rotor 26 determined during the first phase of movement. For example, the control device 20 continues to control the motor as previously, but this control is done taking into account the estimated angular position, this estimation being reliable thanks to the action of the brake 16 as described above.

[0113] Then, due to this control signal produced in step 106, the turns 162 of the spring are released from their braking position and the first end of the spring begins to move in the same direction, thus releasing the mechanical load 2. The load 2 can then exert a resistive torque on the rotor 26. However, at this stage, the information on the position could be estimated accurately during the first phase of the movement. The control signal produced in step 106 is therefore reliable.

[0114] Subsequently, the angular position of the motor 11 can be estimated in a similar manner, by the control device 20, by means of the measured electrical quantities, to update the angular position of the motor. The control signals produced by the control unit 24 are adapted accordingly, depending on the updated estimated position.

[0115] Alternatively, the steps could be performed in a different order. Some steps could be omitted. The described example does not preclude, in other embodiments, other steps being implemented in conjunction and / or sequentially with the described steps.

[0116] [Fig.4] illustrates the evolution, as a function of time (x-axis), of the mechanical torques exerted on the rotor of the motor 11 (top graph of [Fig.4], on the axis noted Crotor) and of the rotor angle (bottom graph of [Fig.4]) when the actuator 4 in operation is subjected to a stop command, the load 2 being moved in an upward direction (more precisely in a direction corresponding to a driven load).

[0117] Graph 60 shows the torque exerted by the load (reference 62), the braking torque (reference 64) exerted by the brake 16 and the motor torque, or electromagnetic torque, exerted by the motor 11 on the rotor 26 (reference 66) during a movement during which the load is carried.

[0118] The evolution of the angular position of the motor 11 is illustrated by curve 68.

[0119] The example is illustrated for several engine operating ranges.

[0120] First the motor rotates at a nominal speed, here chosen equal to 3000 revolutions per minute (rpm) for illustration purposes, but which may be different in practice (first sequence: the speed of the corotor rotor is equal to 3000 rpm). The torque exerted by the load, by the brake and by the motor are constant.

[0121] Then, the motor 11 slows down to reach zero speed (second sequence: the speed of the corotor rotor goes from 3000 rpm to 0 rpm). During this second sequence, the engine torque 66 disappears and torque 62 exerted by the load decreases while braking torque 64 (drag torque) remains constant.

[0122] Then, the motor undergoes a return to the rear (third sequence: corotor return to the rear) under the effect of the drag return while it travels through the angular range corresponding to the unlocking angle. At this stage, the coils 30 of the motor are no longer powered and do not produce any electromagnetic force on the rotor 26. The braking torque 64 changes sign. The corresponding duration of this sequence is noted TL In the example illustrated, the variation in angular position of the motor during this sequence is equal to 60°.

[0123] Finally, the engine remains stationary (fourth sequence: corotor = 0).

[0124] [Fig.5] illustrates the evolution, as a function of time (x-axis), of the mechanical torques exerted on the rotor of the motor 11 (top graph of [Fig.4], on the axis noted Crotor) and of the rotor angle (bottom graph of [Fig.5]) when the actuator 4 in operation is subjected to a stop command, the load 2 being moved in a downward direction, that is to say a direction opposite to that of the direction of rotation of the actuator in the example of [Fig.4].

[0125] Graph 70 shows the torque exerted by the load (reference 72), the braking torque (reference 74) exerted by the brake 16 and the motor torque, or electromagnetic torque, exerted by the motor 11 on the rotor 26 (reference 76) during a movement during which the load is driving.

[0126] The evolution of the angular position of the motor 11 is illustrated by curve 78.

[0127] The example is illustrated for several identical engine operating ranges. to those defined for the example in [Fig.4].

[0128] The operation of the motor 11 is here analogous to the example of [Fig.4], except for the values ​​of the torques 72, 74 exerted by the load 2 and by the brake 16 due to the fact that the load moves here in a downward direction (in driving load) rather than an upward direction (in driven load).

[0129] Other examples are possible without limiting the scope of the invention.

[0130] Thanks to the invention, the spring brake makes it possible to provide a torque close to zero during a rotation angle at engine start-up sufficient to calibrate the control method at each start-up. This avoids any error in the estimation of the position which could result from a change in the operating speed of the engine (for example when changing from a driven load speed to a driving load speed). In addition, defining the angular position of the rotor of the motor during the interval of angular positions corresponding to the unlocking angle at each start-up of the engine makes it possible to guarantee that the motor can start with a low torque, whatever the actual torque to which the actuator will actually be subjected and while using the same method for determining the position at start-up and in operation. operation.

[0131] The embodiments and variations contemplated above may be combined with each other to create new embodiments.

Claims

Claims

1. Electromechanical actuator (4) for a closing, occulting or solar protection installation, the electromechanical actuator comprising an electric motor (11), a mechanical brake (16) coupled to an output of the motor and an electronic control device (20) configured to drive the motor, the motor being a synchronous electric motor with permanent magnets and electronic commutation, the motor being devoid of angular position sensors associated with the rotor, the actuator comprising means for determining the angular position of the rotor from electrical quantities measured between power supply terminals of the motor, the electronic control device (20) being configured to implement steps consisting of: • powering (102) the motor while it is in a stopped position, • automatically estimating (104) the angular position of the rotor with the determination means,• automatically control (106) the motor taking into account the estimated angular position, the steps being carried out over a predefined period corresponding to the motor traveling through a predefined interval of angular positions from the stop position, the brake (16) being configured to, when starting the motor from the stop position, allow rotation of the motor by temporarily preventing the load from exerting torque on the motor during a brake release period adapted to the predefined period.,

2. An electromechanical actuator (4) according to claim 1, wherein the brake (16) is a spring-loaded mechanical brake.

3. An electromechanical actuator (4) according to claim 2, wherein the brake release period is adjustable by adapting the diameter of a helical spring of the spring brake (16) or by adapting the diameter of a metal wire forming a helical spring of the spring brake (16).

4. An electromechanical actuator (4) according to any one of claims 2 or 3, wherein the brake release period is adjustable by adapting the characteristics of a reducer connected to the motor output, between the brake and the motor output.

5. Electromechanical actuator (4) according to any one of claims 2 to 4, wherein the electronic control device (20) is configured to drive the motor with a trapezoidal control law, the brake (16) being configured to, when starting the motor from the stop position, allow rotation of the motor by temporarily preventing the load from exerting a torque on the motor during a brake unlocking period at least equal to the predefined period.

6. Electromechanical actuator (4) according to any one of claims 2 to 5, wherein the electronic control device (20) is configured to drive the motor with a sinusoidal control law, the brake (16) being configured to, when starting the motor from the stop position, allow rotation of the motor by temporarily preventing the load from exerting torque on the motor during a brake release period greater than the predefined period.

7. Closing (1), concealment or solar protection installation, comprising a screen (2) and an electromechanical actuator (4) configured to drive the screen in movement, in which the electromechanical actuator conforms to any one of claims 1 to 6.

8. Method for controlling an electromechanical actuator (4) for a closing, occulting or solar protection installation, the electromechanical actuator comprising an electric motor (11), a mechanical brake (16) coupled to an output of the motor and an electronic control device (20) configured to control the electric motor, the electric motor being a synchronous electric motor with permanent magnets and electronic commutation, the actuator comprising means for determining the angular position of the rotor from electrical quantities measured between power supply terminals of the motor, the method comprising steps consisting of: • starting (102) the motor from a stop position, • automatically estimating (104) the angular position of the rotor with the determination means, • automatically controlling (106) the motor taking into account the estimated angular position, the steps being performed over a predefined period corresponding to the motor traveling through a predefined interval of angular positions from the stop position, the method being such that, upon starting the motor from the stop position, the brake (16) allows rotation of the motor by temporarily preventing the load from exerting torque on the motor for a period adapted to the predefined period.

9. Method for controlling an electromechanical actuator (4) according to the preceding claim, in which the motor is controlled with a trapezoidal control law, the brake (16) allowing, when starting the motor from the stop position, the rotation of the motor by temporarily preventing the load from exerting a torque on the motor during a brake unlocking period at least equal to the predefined period.

10. Method for controlling an electromechanical actuator (4) according to any one of claims 8 or 9, in which the motor is controlled with a sinusoidal control law, the brake (16) being configured to, when starting the motor from the stop position, allow rotation of the motor by temporarily preventing the load from exerting a torque on the motor during a brake unlocking period greater than the predefined period.

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