Method for estimating the internal temperature of a lathe, associated electronic control unit, actuator and home automation device

Description

[0001] The present invention relates to the field of rotating electrical machines such as an electrical power generator or an electric motor. The present invention relates more particularly to a method for estimating the internal temperature of a polyphase rotating electrical machine. The invention also relates to an associated electromechanical actuator and home automation device.

[0002] The present invention may, for example, find an application in the field of home automation installations, particularly in the field of blackout devices, in order to estimate the internal temperature of a motor. Estimating the internal temperature of the motor may, for example, be a prerequisite for starting or not the electric motor of home automation equipment.

[0003] A screening device comprises a motorized drive device moving a screen between at least a first position and at least a second position. The motorized drive device comprises an electromechanical actuator of a movable closing, screening or sun protection element, such as a shutter, a door, a grille, a blind or any other equivalent material, hereinafter referred to as a “screen”.

[0004] Some actuators intended for installation in buildings and intended for operating screens include a collector or brushless motor (also called « brushless » according to Anglo-Saxon terminology). The motor placed in the actuator is subject to quasi-adiabatic heating, due to the cylindrical casing of the actuator (increasingly often made of plastic) or due to the winding tube rotated by the actuator and surrounding the latter: these different walls, to which are added the wound mobile product and the box housing the assembly, limit exchanges with the ambient air.

[0005] Since this heating can reach very high values, it is important to be able to measure the motor temperature in order to guarantee safety against fire risks. This knowledge also makes it possible to optimize the motor's power supply conditions, to act on the control durations and / or the power supply.

[0006] EP 1 677 411 A1, US 2010 / 156338 A1 and EP 2 743 713 A1 disclose a technique for estimating the temperature of motor windings. It is known to use a thermistor of the NTC type for "Negative Temperature Coefficient" or PTC for "Positive Temperature Coefficient" in a motor such as an asynchronous motor. However, this solution requires adding an additional component to the motor and thus increases its price. In addition, in the case of a brushless motor, it is not always easy to add a thermistor to the motor. This requires adding an additional component to the motor and running two additional wires.

[0007] Another solution is to oversize the motor so that it never overheats. This solution is not very economical because it increases the cost of the motor and therefore the actuator.

[0008] It is also known to limit the operating time of an engine to prevent it from overheating. From a duration of use greater than a predetermined threshold value, a mechanism prevents the engine from restarting. The mechanism then imposes a minimum rest time on the engine before allowing it to restart. However, these different durations are not based on any real-time measurement of the engine temperature but depend on empirical values. Due to these inaccuracies, the user may not understand why he cannot start his engine.

[0009] One aim of the invention is in particular to correct all or part of the aforementioned drawbacks by proposing a solution making it possible to precisely estimate the internal temperature of an engine while controlling the precision of the measurement.

[0010] The invention is disclosed in independent claims 1 and 11.

[0011] Other features and advantages of the present invention will appear more clearly on reading the description below, given for illustrative and non-limiting purposes, and made with reference to the appended drawings, in which: There figure 1 is a schematic cross-sectional view of an exemplary embodiment of a home automation installation according to the invention; The figure 2 represents a schematic perspective view of the home automation installation illustrated in figure 1 ; There figure 3 is a partial cross-sectional schematic view of the home automation system illustrated in figure 2 comprising an electromechanical actuator according to an exemplary embodiment of the invention; The figure 4 represents a first example of an embodiment of an electronic control unit according to the invention; The figure 5 represents an equivalent diagram of an exemplary embodiment of an adjustable precision measuring device electrically connected to a motor when it is traversed by a direct current; The figures 6 And 7 represent other examples of embodiment of an electronic control unit according to the invention; The figure 8 is a flowchart representing steps of an example mode of implementation of the method for estimating the internal temperature of an engine.

[0012] Subsequently, the invention will be described with respect to an application to an electric motor. This description is in no way limiting and can be applied to any type of polyphase rotating electrical machine such as electric motors or electrical energy generators.

[0013] First of all, we describe, with reference to the figures 1 And 2, an embodiment of a home automation installation for closing or solar protection in accordance with the invention and installed in a building comprising an opening 1, window or door, equipped with a screen 2 belonging to a concealment device 3, in particular a motorized roller shutter.

[0014] The occultation device 3 may be a roller shutter, a canvas blind or one with adjustable slats, in particular a terrace blind or a Venetian blind, a gate or a garage door. The present invention applies to all types of occultation device.

[0015] The screen 2 of the occultation device 3 is wound on a winding tube 4 driven by a motorized drive device 5 and movable between a wound position, in particular high, and an unwound position, in particular low.

[0016] The movable screen 2 of the occultation device 3 is a closing, occultation and / or solar protection screen, wound on the winding tube 4 whose internal diameter is substantially greater than the external diameter of an electromechanical actuator 11, so that the electromechanical actuator 11 can be inserted into the winding tube 4, during the assembly of the occultation device 3.

[0017] The motorized drive device 5 comprises the electromechanical actuator 11, in particular of the tubular type, making it possible to rotate the winding tube 4, so as to unwind or wind the screen 2 of the occulting device 3.

[0018] The shading device 3 comprises the winding tube 4 for winding the screen 2, where, in the mounted state, the electromechanical actuator 11 is inserted into the winding tube 4.

[0019] In a known manner, the roller shutter, which forms the concealment device 3, comprises an apron comprising horizontal slats hinged to each other, forming the screen 2 of the roller shutter 3, and guided by two lateral slides 6. These slats are joined when the apron 2 of the roller shutter 3 reaches its lower unrolled position.

[0020] In the case of a roller shutter, the upper rolled-up position corresponds to the support of an L-shaped final end blade 8 of the apron 2 of the roller shutter 3 against an edge of a box 9 of the roller shutter 3, and the lower unrolled position corresponds to the support of the final end blade 8 of the apron 2 of the roller shutter 3 against a threshold 7 of the opening 1.

[0021] The first slat of the apron 2 of the roller shutter 3, opposite the end slat, is connected to the winding tube 4 by means of at least one articulation 10, in particular a band-shaped attachment piece.

[0022] The winding tube 4 is arranged inside the box 9 of the roller shutter 3. The apron 2 of the roller shutter 3 winds and unwinds around the winding tube 4 and is housed at least partly inside the box 9.

[0023] Generally, the trunk 9 is arranged above the opening 1, or in the upper part of the opening 1.

[0024] The motorized drive device 5 is controlled by a control unit. The control unit may be, for example, a local control unit 12, where the local control unit 12 may be connected in a wired or wireless connection to a central control unit 13. The central control unit 13 controls the local control unit 12, as well as other similar local control units distributed throughout the building.

[0025] The central control unit 13 may be in communication with a remote weather station outside the building, including, in particular, one or more sensors which may be configured to determine, for example, a temperature, a brightness, or even a wind speed.

[0026] The local control unit may be a control point 12, in particular a wall-mounted one, or a remote control 14. The control unit 12, 14 may comprise a keyboard comprising selection elements and / or activation elements and, possibly, a display element, so as to allow a user to intervene on the electromechanical actuator 11 and / or the central control unit 13.

[0027] The electromechanical actuator 11 can be controlled by the control point 12 by means of wireless communication.

[0028] The electromechanical actuator 11 is preferably configured to execute the commands for unrolling or rolling up the screen 2 of the occulting device 3 which can be issued, in particular, by the control point 12 or the remote control 14.

[0029] The control unit 12, 14 may comprise a controller and a control command transmission module. The control command transmission module of the control point may thus enable the transmission of commands by wireless means. In particular, the control command transmission module of the control unit is configured to transmit radio control commands.

[0030] The control unit 12, 14 may also comprise a module for receiving control orders.

[0031] In an exemplary embodiment, the control order transmission module and the control order reception module are included in the same module.

[0032] Alternatively, the control order issuing module and the control order receiving module are included in two separate modules.

[0033] Advantageously, the control point 12 comprises fixing elements, not shown, in particular by elastic snap-fastening.

[0034] In an exemplary embodiment, the control point 12 is installed on a window post of the home automation system. The assembly of the control point 12 on the post is implemented by means of the fixing elements configured to cooperate with a hole provided in the post.

[0035] We will now describe in more detail and with reference to the figure 3 , the electromechanical actuator 11 belonging to the home automation installation of the figures 1 And 2 .

[0036] The electromechanical actuator 11 comprises an electric motor 16. The electric motor 16 comprises a rotor and a stator, not shown and positioned coaxially around an axis of rotation X, which is also the axis of rotation of the winding tube 4 in the mounted configuration of the motorized drive device 5.

[0037] The electromechanical actuator 11 is supplied with electrical energy by a mains power supply network, or by means of a battery, which can be recharged, for example, by a photovoltaic panel. The electromechanical actuator 11 makes it possible to move the screen 2 of the occulting device 3.

[0038] Here, the electromechanical actuator 11 comprises an electrical power supply cable 18 allowing it to be supplied with electrical energy from the mains power supply network.

[0039] Control means of the electromechanical actuator 11 according to the invention, allowing the screen 2 of the occulting device 3 to be moved, comprise at least one electronic control unit 15. This electronic control unit 15 is capable of putting the electric motor 16 of the electromechanical actuator 11 into operation, and, in particular, of allowing the electric motor 16 to be supplied with electrical energy.

[0040] Thus, the electronic control unit 15 controls, in particular, the electric motor 16, so as to open or close the screen 2, as described previously.

[0041] The electronic control unit 15 also comprises a module 27 for receiving control orders, in particular electrical orders emitted by an order transmitter, such as the control point 12 and / or the remote control 14 intended to control the electromechanical actuator 11.

[0042] The control command reception module of the electronic control unit 15 can thus allow the reception of commands transmitted by wireless means. In particular, the control command reception module of the electronic control unit 15 is configured to receive radio control commands.

[0043] The control means of the electromechanical actuator 11 comprise hardware and / or software means.

[0044] By way of non-limiting example, the hardware means may comprise at least one microcontroller integrated into the electronic control unit 15.

[0045] In the example embodiment illustrated on the figure 3 , the electronic control unit 15 is arranged, in other words integrated, inside the casing 17 of the electromechanical actuator 11.

[0046] In another exemplary embodiment, the electronic control unit 15 is arranged outside the casing 17 of the electromechanical actuator 11 and, in particular, mounted on the support 23 or in the closing element 21.

[0047] The casing 17 of the electromechanical actuator 11 is preferably cylindrical in shape.

[0048] In one embodiment, the casing 17 is made of a metallic material. The material of the casing of the electromechanical actuator is not limiting and may be different. It may be, in particular, a plastic material.

[0049] The electromechanical actuator 11 also comprises a gear reduction device 19 and an output shaft 20.

[0050] The electromechanical actuator 11 may also comprise an end-of-travel and / or obstacle detection device, not shown, which may be mechanical and / or electronic.

[0051] Advantageously, the electric motor 16 and the gear reduction device 19 are arranged inside the casing 17 of the electromechanical actuator 11.

[0052] The output shaft 20 of the electromechanical actuator 11 is arranged inside the winding tube 4, and at least partly outside the casing 17 of the electromechanical actuator 11.

[0053] The output shaft 20 of the electromechanical actuator 11 is coupled by a connecting element 22 to the winding tube 4, in particular a wheel-shaped connecting element.

[0054] The electromechanical actuator 11 also comprises a sealing element 21 for one end of the casing 17.

[0055] Here, the casing 17 of the electromechanical actuator 11 is fixed to a support 23, in particular a cheek, of the box 9 of the concealing device 3 by means of the closing element 21 forming a torque support, in particular a closing and torque recovery head. In such a case where the closing element 21 forms a torque support, the closing element 21 is also called a fixed point of the electromechanical actuator 11.

[0056] The home automation installation, in particular the control point 12 and the electromechanical actuator 11, in particular the controller 24 and the electronic control unit 15, comprises hardware and / or software means for governing its operation in accordance with the method which is the subject of the invention. The software means may, in particular, comprise a computer program code adapted to carrying out the steps of the method according to the invention, when the program is executed on a computer.

[0057] The electronic control unit 15 is configured to be electrically connected to a polyphase rotating electrical machine, such as an electric motor 16 or an electrical energy generator 16', in order to control and / or command it. For this purpose, the electronic control unit 15 comprises a plurality of output terminals. Each output terminal is configured to be electrically connected to an input terminal of the electric motor 16.

[0058] The electronic control unit 15 comprises a variable precision measuring device configured to estimate the value of the internal temperature of a motor electrically connected to the terminals of the electronic control unit and to deliver a signal proportional to the internal temperature of the motor electrically connected to the terminals of the electronic control unit.

[0059] The variable precision measuring device comprises a power source, configured to deliver a continuous power electrical signal, referenced to a fixed potential reference GND, for a predetermined duration.

[0060] The adjustable precision measuring device comprises a sensor. The sensor may be a current sensor configured to deliver a signal proportional to the current absorbed by the adjustable precision measuring device when at least two output terminals 150 of the electronic control unit 15 are electrically connected to input terminals 160 of the polyphase electric motor 16.

[0061] The adjustable precision measuring device also includes an adjustment resistor R ajust whose value determines the measurement accuracy. The adjustment resistor can be one or more fixed value resistors and / or a variable resistor.

[0062] The electrical power supply source, the adjustment resistor R ajust and the sensor R mesure are electrically connected in series and arranged between two of the output terminals 150 of the electronic control unit 15. The measuring device may comprise an analog-digital converter electrically connected to the terminals of the sensor R mesure in order to read the signal delivered by the latter and provide a sampled signal of the delivered signal. According to one embodiment, the analog-digital converter is an output of a microcontroller or a microprocessor. It may be, for example, an output of the control module.

[0063] There figure 4 represents an exemplary embodiment of an electronic control unit 15.

[0064] The electronic control unit 15 comprises a plurality of output terminals 150 configured to be electrically connected with the plurality of input terminals 160 of a polyphase motor. In the example illustrated in the figure 4 , the electronic control unit 15 comprises three output terminals intended to be electrically connected with the three input terminals of a three-phase electric motor. Of course, this example is in no way limiting and the electric motor 16 may be a direct current electric motor, a two-phase electric motor or any other type of electric motor comprising a greater number of phases. Similarly, the number of output terminals 150 of the electronic control unit 15 will be of the number of

[0065] The electronic control unit 15 comprises a polyphase inverter configured to deliver, sequentially, electrical signals between two output terminals taken from among the plurality of output terminals and an adjustable precision measuring device configured to estimate the internal temperature of the electric motor electrically connected to the electronic control unit.

[0066] The inverter comprises a plurality of branches B1, B2, B3 electrically connected in parallel between a first connection point C1 and a second connection point C2. Each branch B1, B2, B3 comprises a first electronic switch K1, K2, K3 electrically connected to the first connection point C1 and electrically connected in series with an associated second electronic switch K4, K5, K6. The second electronic switch is electrically connected to the second connection point C2. The simultaneous switching of a first electronic switch and a second electronic switch other than its associated electronic switch makes it possible to power at least one winding E1, E2, E3 of the motor.

[0067] On the example of the figure 4 , the inverter presented is a three-phase inverter and the motor is a three-phase electric motor whose windings E1, E2, E3 are electrically connected in a delta arrangement. This assembly example is in no way limiting. The windings of the rotating electrical machine 16, 16' can be electrically connected in a star arrangement as illustrated in the figures 6 And 7 .

[0068] The simultaneous switching of a first electronic switch and a second switch other than the switch associated with the first electronic switch from a blocking state to an on state makes it possible to supply at least one winding E1, E2, E3 of the motor 16.

[0069] A first connection point C1 of the inverter is electrically connected to a first terminal V bus of the electrical energy supply source and a second connection point C2 is electrically connected to a second terminal GND of the power source via a current sensor.

[0070] As an illustration, on the figure 4 , the sensor is a measuring resistor R measure (or "shunt" in English terminology). When a current passes through the measuring resistor, the latter provides, at its terminals, a voltage V measure proportional to the value of the current absorbed by the adjustable precision measuring device.

[0071] Each branch B1, B2, B3 of the inverter includes a midpoint electrically connected to an output terminal.

[0072] The first electronic switches K1, K2, K3 are distributed in a first group of switches and the second electronic switches K4, K5, K6 are distributed in a second group of switches.

[0073] The switching of the electronic switches K1, K2, K3, K4, K5, K6 is controlled by control signals generated by a control module (not shown) forming a predetermined control law. The control law is broken down into a succession of switching sequences, each sequence corresponding to a set of signals for a determined duration. Each time a first electronic switch K1, K2, K3 and a second electronic switch other than its associated switch K4, K5, K6 switch from its blocking state to its conducting state, at least one of the windings E1, E2 and E3 of the motor is powered. The control law is programmed so that the inverter delivers, sequentially, a voltage between two output terminals taken from among the plurality of output terminals 150 of the electronic control unit 15.

[0074] When the input terminals 160 of an electric motor 16 are electrically connected to the output terminals 150 of the electronic control unit 15, the electrical signals delivered by the inverter are programmed to sequentially power the stator windings of the polyphase electric motor in order to generate a rotating electric field capable of driving the rotor in rotation.

[0075] An analog-to-digital converter is electrically connected to the sensor terminals in order to measure the signal proportional to the current flowing in the adjustable-precision measuring device. According to one embodiment, the input of the converter may be an input of a microcontroller or a microprocessor. It may be, for example, a microcontroller belonging to the control module controlling the electronic switches, K1, K2, K3, K4, K5, K6 of the inverter.

[0076] On the example of the figure 4 , the power supply source of the inverter is common with that of the adjustable precision measuring device.

[0077] The adjustment resistor R ajust is electrically connected in series with an electronic switch K7, called the seventh switch. The adjustment resistor R ajust and the seventh electronic switch K7 are electrically connected between the midpoint U of a branch B1 of the inverter and a connection point C2 of the inverter. The electronic switch K7 can be, for example, a transistor, a triac or any other type of equivalent electronic switch. The electronic switch K7 can be, for example, controlled by the control module driving the electronic switches, K1, K2, K3, K4, K5, K6 of the inverter.

[0078] The seventh electronic switch K7, electrically connected in series with the adjustment resistor, is intended to operate with an associated electronic switch K2, K3 forming part of a branch of the inverter different from that to which the seventh electronic switch K7 is electrically connected. In addition, the associated electronic switch K2, K3 to the seventh electronic switch K7 is part of a group of switches different from that to which the seventh switch K7 belongs.

[0079] The seventh switch K7 and its associated first switch K2 and / or K3 are configured to switch together from a blocked state to an on state during a predetermined time interval so that the electrical power supply source can deliver a continuous power signal during this same predetermined time interval. The switching of the electronic switches K2, K3, K7 can be ensured, for example, by the control module.

[0080] According to an alternative embodiment, the electrical power supply source is electrically connected to a microprocessor or microcontroller, for example, an output of the control module, the microprocessor being programmed to switch the output of the power source into an on state during the predetermined time interval.

[0081] In reference to the figure 4 , when the seventh switch K7 and its associated switch K2 and / or K3 are in an on state, a direct current flows in the adjustable precision measuring device and in at least one winding of the motor electrically connected to the electronic control unit.

[0082] There figure 5 represents an example of an equivalent diagram of the system formed by the adjustable precision measuring device when a direct current flows through it and when at least one winding of an electric motor is electrically connected to its terminals. In this diagram, it is assumed that the direct electrical power supply source delivers a voltage V.

[0083] There figure 6 represents a second embodiment of an electronic control unit 15. In this embodiment, the electrical power supply source Vcc of the adjustable precision measuring device and the electrical power supply source V bus of the inverter are different. According to one embodiment, the electrical power supply source of the adjustable precision measuring device may be a low voltage source, delivering for example, a direct voltage of the order of 12V. The power source of the inverter may be a high voltage source delivering a direct voltage of amplitude greater than 42V. The use of a power source delivering a voltage of amplitude lower than that of the power source of the inverter makes it possible to circulate in the measuring device, and therefore in the adjustable resistor, a current of lower amplitude when measuring the internal temperature of the motor.Advantageously, this makes it possible to reduce the energy dissipated, for example, in the adjustment resistor during the measurement step.

[0084] The electrical power supply source of the adjustable precision measuring device can be electrically connected to the midpoint V of a branch B2 of the inverter, different from branch B1 to which the seventh electronic switch K7 is electrically connected.

[0085] According to another embodiment illustrated on the figure 6 , the electrical power supply source of the adjustable precision measuring device is electrically connected to the midpoint of a branch of the inverter via a diode D8. The diode D8 is configured to only allow current to flow from the power supply source of the adjustable precision measuring device to the midpoint V of the branch to which the diode is electrically connected. Advantageously, when the inverter is powered, the diode D8 makes it possible to block the current flowing back to the power supply of the adjustable precision measuring device.

[0086] There figure 7 presents another embodiment of the electronic control unit. In this embodiment, the electrical power supply source of the adjustable precision measuring device is electrically connected to the midpoint V of a branch of the inverter, different from the branch B1 to which the seventh electronic switch K7 is electrically connected, via an eighth electronic switch K8. The eighth electronic switch K8 may be, for example, a transistor, a triac or any other type of equivalent electronic switch. The switch K8 is intended to switch simultaneously with the second switch K4 of the adjustable precision measuring device. Advantageously, when the inverter is powered, the eighth switch K8 prevents the current flowing in the inverter from flowing back up to the power supply of the adjustable precision measuring device.The eighth electronic switch K8 can, for example, be controlled by the control module controlling the electronic switches, K1, K2, K3, K4, K5, K6 of the inverter. In this figure, each output terminal 150 of the electronic control unit 15 is electrically connected to an input terminal 160 of a polyphase electrical energy generator 16'.

[0087] Another subject of the invention is an electromechanical actuator, for example, configured for maneuvering a movable element. The actuator comprises an electronic control unit as described above and a polyphase electric motor whose input terminals are electrically connected to the output terminals of the electronic control unit.

[0088] According to one embodiment, the electronic control unit of the electromechanical actuator comprises a control module configured to control the electric motor of the actuator. The control module is also configured to test the internal temperature of the electric motor before each attempt to start said motor. For this purpose, the control module compares the value of the signal delivered by the measuring device with a predetermined threshold value corresponding to a threshold temperature. If the internal temperature of the electric motor is lower than a predetermined threshold value, the control module authorizes the starting of the motor. Otherwise, if the value of the internal temperature of the motor is strictly higher than the predetermined threshold value, the control module blocks the starting of the electric motor.

[0089] According to another embodiment, the control module is configured to compare the value of the signal delivered by the measuring device with a predetermined setpoint.

[0090] The present invention also relates to a method for estimating the internal temperature of a polyphase rotating electrical machine.

[0091] There figure 8 presents the main steps of an example of implementation of a method for estimating the internal temperature of an engine according to the invention. This may be the motor of an electromechanical actuator configured for the operation of a mobile element. The method is implemented by an electronic control unit as described previously and in particular by the adjustable precision measuring device.

[0092] The method comprises a first step Etp1 of powering at least one winding of the motor by applying a direct voltage between two output terminals of the electronic control unit for a predetermined time interval.

[0093] During the first step Etp1, a direct voltage is applied between two output terminals of the electronic control unit via the adjustable precision measuring device. The voltage is applied for a predetermined time interval. The duration of the time interval depends on the parameters of the motor winding(s) electrically connected to the output terminals of the electronic control unit between which a voltage is applied. These parameters are the resistance and the inductance of the winding(s). The duration of the predetermined time interval is chosen so that it is greater than the time constant of the powered windings in order to be in a continuous steady state. In continuous mode, the windings behave like resistors. Advantageously, this avoids being disturbed by the effects of the inductance of the windings. As a reminder, the time constant is given by the formula: τ = L R In which: τ represents the time constant, L represents the inductance of the powered winding(s), R represents the resistance of the powered winding(s).

[0094] For illustration purposes, with an inductance of the powered winding(s) of 1.2 mH and a resistance of the powered winding(s) of 1.2Ω, a time constant of 1 ms is obtained.

[0095] Preferably, the duration of the predetermined time interval is chosen close to the time constant, but always greater than the time constant of the powered windings, in order to reduce the time during which a current flows in the adjustable precision measuring device and therefore to reduce the energy dissipated in the adjustment resistor during the measurement. Advantageously, when sizing the adjustable resistor, this makes it possible to reduce the maximum power acceptable by the resistor.

[0096] The value of the resistance of the powered winding(s) varies according to the temperature, the value of the time constant τ is determined by considering a worst case to estimate the value of the winding resistance. For example, when the windings are made of copper or aluminum, the worst case corresponds to the lowest temperature that the windings of the electric motor could reach.

[0097] During this step, the rotor is not rotated, the measurement of the internal temperature of the motor is carried out when the motor is stopped.

[0098] The estimation method then comprises a step Etp2 of measuring the current flowing in the adjustable-precision measuring device during the predetermined time interval. It is assumed that the amplitude of the current flowing in the adjustable-precision measuring device is substantially equal to that of the total current flowing in the powered winding(s) during the predetermined time interval. The current measurement is obtained via the current sensor as a measuring resistor. The value of the signal proportional to the current is read by an analog-digital converter, for example an analog-digital input of a microcontroller or a microprocessor.

[0099] Finally, the estimation method includes a step Etp3 of estimating the internal temperature of the motor from the signal proportional to the current flowing in the adjustable precision measuring device.

[0100] Electric motor windings are typically made of copper, a metal whose resistance varies with temperature. Since the resistance of an electric motor's windings varies with temperature, this element can be used as a temperature sensor to estimate the internal temperature of the electric motor. Advantageously, this solution provides a signal proportional to the internal temperature of the motor without having to modify the motor or add any additional components to the motor.

[0101] Subsequently, the resistance of the powered winding(s) will be called “winding resistance”.

[0102] The value of the winding resistance of an electric motor can be defined by the relation: R enroul = R T 0 + α T − To

[0103] In which: T represents the winding temperature, T 0 represents a predetermined temperature, R T0 represents the value of the winding resistance at temperature T 0 , R winding represents the value of the winding resistance at temperature T, α represents the sensitivity of the winding resistance as a function of temperature. This coefficient depends on the nature of the metal of the windings.

[0104] When the circuit of the adjustable precision measuring device is closed by at least one winding of an electric motor, when the current sensor is a measuring resistor R measure and when a current I flows in the adjustable precision measuring device, the current produces, at the terminals of the powered winding(s), a voltage V enroul . The current also produces a voltage V ajust at the terminals of the adjustment resistor R ajust and a voltage V mesure at the terminals of the measuring resistor R mesure . With reference to the figure 5 , in this case we have the relationship: V enroul + V ajust + V mesure = R enroul + R ajust + R mesure * I = V

[0105] Where V represents the amplitude of the voltage delivered by the DC power supply source.

[0106] We therefore have the relationship: R enroul = V I − R ajust + R mesure

[0107] The measurement of the voltage V measurement at the terminals of the measurement resistance R measurement makes it possible to know the value of the current I circulating in the measuring device with adjustable precision by the relation: V mesure = R mesure * donc = V mesure / R mesure

[0108] Relations (3) and (4) allow us to write: R enroul = V ∗ R mesure V mesure − R ajust + R mesure

[0109] As stated previously, the value of the winding resistance is also defined by relation (1). This relation allows us to write: T = 1 α αT 0 + T enroul − R T 0

[0110] Finally, by integrating the estimated value of the winding resistance R wound using relation (5), into relation (6) we can determine the temperature of the winding(s) supplied during the measurement step Etp2. If we consider that each winding of the motor has the same temperature and that the internal temperature of the motor is equal to the temperature of its windings, relations (5) and (6) make it possible to estimate the internal temperature of the electric motor.

[0111] According to one embodiment, the step Etp3 of estimating the internal temperature of the motor may comprise a sub-step Etp31 of estimating the amplitude of the current flowing in the adjustable-precision measuring device using the signal supplied by the sensor. The estimation step may then comprise a sub-step Etp32 of estimating the value of the winding resistance from the value of the estimated current and finally, a sub-step Etp33 of estimating the internal temperature of the motor using the value of the winding resistance.

[0112] The present invention also relates to a method for designing an electronic control unit capable of controlling a polyphase rotating machine 16, 16' as described previously. The design method comprises a step of dimensioning the value of an adjustment resistor of the adjustable precision measuring device.

[0113] The sizing step includes a first step of choosing the desired sensitivity for estimating the internal temperature of the electric motor.

[0114] The dimensioning step then comprises a step of estimating the value of the total resistance of the system formed by the adjustable precision measuring device and the electric motor 16 electrically connected to said adjustable precision measuring device.

[0115] We refer to the figure 5 and we consider a variation ΔT of the temperature of the powered windings, equal to the desired sensitivity. With reference to relations (1) and (2), a variation of temperature ΔT causes a variation ΔR of the value of the winding resistance and a variation -ΔI of the current flowing in the circuit.

[0116] Relation (1) allows us to write the relation: ΔR = α . ΔT

[0117] In which: ΔT represents the winding temperature variation, ΔR represents the variation of the winding resistance due to the variation of temperature ΔT α represents the sensitivity of the winding resistance as a function of temperature.

[0118] The variation in the value of the winding resistance ΔR is therefore directly proportional to the variation in temperature ΔT.

[0119] Let R g be the total resistance of the circuit at a given temperature. The value of the total resistance is equal to: R g = R enroul + R ajust + R mesure

[0120] In which: R g represents the value of the total resistance of the circuit at a given temperature, R winding represents the value of the winding resistance at the predetermined temperature T, R adjust represents the value of the adjustment resistance, R measure represents the value of the measurement resistance.

[0121] Let I be the value of the current flowing in the circuit at the predetermined temperature T, we have the relationship: V = R g . I

[0122] The current variation -ΔI due to the temperature variation ΔT is equal to: − ΔI = I − ΔI − I

[0123] Thanks to relations (7) and (8) we have the relations: Δ I = V R g − V R g + Δ R Δ I = V R g − V R g + α . Δ T

[0124] Let δT be the desired temperature sensitivity for the adjustable precision measuring device.

[0125] The quantum of the analog-to-digital converter electrically connected to the terminals of the current sensor R measure is given by the relation; q = V N

[0126] In which: q represents the quantum of the analog-to-digital converter, V represents the value of the voltage across the circuit, N represents the number of bits of the analog-digital converter,

[0127] In reference to the figures 4 , 6 And 7, the value of the voltage across the circuit terminals is equal to V_bus, Vdd and (Vdd-Vd) respectively, Vd representing the value of the voltage drop due to diode D8.

[0128] Let δI be the variation in current due to a variation in the temperature of the powered windings equal to δT.

[0129] If the adjustable precision measuring device is to have the desired sensitivity, the analog-to-digital converter electrically connected to the terminals of the current sensor must be sized so that it can measure the signal proportional to a current value equal to δI. It is therefore necessary that: q = R mesure δI

[0130] Solving the system formed by relations (12) and (14) allows us to estimate the value of the total resistance of the system formed by the adjustable precision measuring device and the electric motor electrically connected to said adjustable precision measuring device. Using the previous notations, we obtain the following equation: q . R g 2 + q . α . δT . R g − α . δT . R mesure . V = 0

[0131] Solving equation (15) makes it possible to estimate the value of the total resistance of the system formed by the adjustable precision measuring device and the electric motor electrically connected to said adjustable precision measuring device.

[0132] From the estimated value of the total resistance of the system and from relation (8), we can deduce the value of the adjustment resistance to be placed in the adjustable precision measuring device in order to obtain the desired sensitivity for estimating the internal temperature of the engine.

[0133] The dimensioning step may then comprise a step of estimating the power dissipated in the adjustment resistor as well as the energy dissipated in the adjustment resistor during the predetermined measurement time.

[0134] For illustration purposes, we refer to the figure 7 . It is assumed that the electrical power supply source of the adjustable precision measuring device delivers a voltage equal to 3.3V, that at the temperature of 25°C the value of the winding resistance is equal to 0.7Ω and that at the temperature of 100°C the value of the winding resistance is equal to 0.9Ω. It is also assumed that the current sensor is a measuring resistor with a value of 0.33Ω and that the analog-to-digital converter electrically connected to the terminals of the current sensor is a 12-bit converter.

[0135] Under these conditions, if we want the adjustable precision measuring device to have a sensitivity equal to 1°C, by solving equation (15) we obtain a value of the adjustment resistance equal to 2.85Ω.

[0136] Under the same conditions, if we want the adjustable precision measuring device to have a sensitivity equal to 5°C, we obtain a value of the adjustment resistance equal to 7.05Ω.

[0137] In reference to the figure 4 , the electronic control unit according to the invention is distinguished from a conventional polyphase motor control circuit by the adjustment resistor R ajust and the electronic switch K7. Advantageously, the addition of these two components makes it possible to obtain a precise measurement of the temperature of the windings of the motor electrically connected to the terminals of the electronic control unit. The choice of the value of the adjustment resistor makes it possible to define the value of the desired precision

[0138] The different implementations, embodiments and variants defined above may be combined to generate new implementations and embodiments of the invention.

Claims

1. Electronic control unit (15) configured to control a polyphase rotating electrical machine (16, 16'), the electronic control unit (15) comprising a plurality of output terminals (150), each output terminal (150) being configured to be electrically connected to an input terminal (160) of the polyphase rotating electrical machine (16, 16'), the electronic control unit being characterized in that it comprises an adjustable-accuracy measuring device having : - an electrical power supply (V_bus, Vdd) configured to deliver a continuous power signal, the power signal being delivered for a predetermined time interval, - an adjustment resistor (Rajust) configured to set the measurement accuracy of the measurement device , - a sensor (Rmeasure) configured to deliver a signal proportional to the current drawn by the measurement device when at least two of the output terminals (150) of the electronic control unit (15) are electrically connected to input terminals (160) of the polyphase rotating electrical machine (16, 16'), the power supply (V_bus, Vdd), the adjustment resistor (Rajust) and the sensor (Rmesure) being electrically connected in series and arranged between two of the output terminals (150) of the electronic control unit (15), the precision-adjustable measuring device further comprising an electronic switch (K7), called seventh switch, configured to limit in time the delivery of the supply signal from the electrical power supply source (V_bus, Vdd) of the precision-adjustable measuring device to the electronic control unit.

2. Electromechanical actuator characterized in that it comprises an electronic control unit (15) according to claim 1, comprising a polyphase inverter comprising a plurality of output terminals (150) and a polyphase rotating electrical machine (16, 16') comprising a plurality of input terminals (160), each input terminal of the rotating machine being electrically connected to an output terminal of the electronic control unit, the electronic control unit (15) being configured to estimate the internal temperature of the polyphase rotating machine (16, 16') by means of the adjustable-accuracy measuring device.

3. Electromechanical actuator according to the preceding claim in which the value of the adjustable resistor (Rajust) is determined as a function of the desired measurement accuracy of the measuring device, of parameters of the electrical power supply source, of parameters of the analog-to-digital converter and of parameters of the rotating electrical machine (16, 16').

4. Electromechanical actuator according to the preceding claim in which the rotating machine electric polyphase is an electric polyphase motor (16).

5. Electromechanical actuator according to the preceding claim, wherein the inverter comprises a plurality of branches (B1, B2, B3) electrically connected in parallel between a first connection point (C1) and a second connection point (C2), each branch (B1, B2, B3) comprising a first electronic switch (K1, K2, K3) electrically connected to the first connection point (C1) and electrically connected in series with an associated second electronic switch (K4, K5, K6), the second electronic switch being electrically connected to the second connection point (C2) and being such that simultaneous switching of a first electronic switch (K1, K2, K3) and a second electronic switch (K4, K5, K6) other than its associated electronic switch enables power to be supplied to at least one winding (E1, E2, E3) of the polyphase electric rotating machine, the seventh electronic switch (K7) being controlled by a control module which also controls the first and second electronic switches (K1, K2, K3, K4, K5, K6) of the inverter.

6. Electromechanical actuator according to the preceding claim, in which the seventh electronic switch (K7) and an associated first electronic switch (K2, K3) are configured to switch together from a blocked state to a conducting state for a predetermined time interval.

7. Electromechanical actuator according to one of claims 5 or 6, in which the electrical power supply source of the adjustable-accuracy measuring device is electrically connected to a midpoint (V) of a branch (B1, B2, B3) of the inverter, different from the branch (B1, B2, B3) to which the seventh electronic switch (K7) is electrically connected, via a further electronic switch (K8), called eighth switch, which is designed to switch simultaneously with a second switch (K4, K5, K6) of the adjustable-precision measuring device.

8. Electromechanical actuator according to one of claims 2 to 7 in which the electronic control unit (15) comprises a control module configured to test the internal temperature of the motor before each attempt to start the rotating machine (16, 16') and to authorize starting of the rotating machine (16, 16') only if the internal temperature of the polyphase rotating electrical machine (16, 16') is below a predetermined threshold value.

9. Home automation device characterized in that it comprises an actuator according to one of the claims2 to 8.

10. Motorization assembly for a closure or sun protection screen, characterized in that it comprises an electromechanical actuator according to one of the claims 2 to 8.

11. Method for estimating the internal temperature of a multiphase rotating electrical machine (16, 16') comprising a plurality of input terminals (160) and a plurality of windings (E1, E2, E3), each input terminal of the rotating machine being connected electrically to an output terminal of an electronic control unit according to claim 1, the electronic control unit (15) further comprising a measuring device with adjustable accuracy comprising : - a power supply (V_bus, Vdd) configured to deliver a continuous power signal, the power signal being delivered for a predetermined time interval, - an adjustment resistor (Rajust) configured to set the measurement accuracy of the measuring device, - a sensor (Rmeasure) configured to deliver a signal proportional to the current absorbed by the measurement device when at least two of the output terminals (150) of the electronic control unit (15) are electrically connected to input terminals (160) of the multiphase rotating electrical machine (16, 16'), the electrical power supply (V_bus, Vdd), the adjustment resistor (Rajust) and the sensor (Rmesure) being electrically connected in series and arranged between two of the output terminals (150) of the electronic control unit (15), the precision-adjustable measuring device further comprising an electronic switch (K7), called seventh switch, configured to limit in time the delivery of the supply signal from the electrical power supply source (V_bus, Vdd) of the precision-adjustable measuring device to the electronic control unit, the process being characterized in that it comprises: - a step (Etp1) of establishing a continuous voltage between two output terminals (150) of the electronic control unit (15) for a predetermined time interval by means of the electrical power supply (V_bus, Vdd), the rotor not being driven in rotation during this step, the measurement of the motor's internal temperature being carried out when the motor is at a standstill, - a step (Etp2) in which the sensor (Rmeasure) supplies a signal representative of a current absorbed by the measurement device during the predetermined time interval, - a step (Etp3) of estimating the internal temperature of the rotating electrical machine (16, 16') from the signal supplied by the sensor (Rmesure), the value of the accuracy of the estimate being defined by the value of the adjustment resistor (Rajust).

12. Method according to the preceding claim in which the step (Etp3) of estimating the internal temperature comprises : - a sub-step (Etp31) for estimating the amplitude of a current flowing in the precision-adjustable measuring device using the signal supplied by the sensor (Rmeasure), - a sub-step (Etp32) for estimating the resistance value (Renroul) of at least one winding (E1, E2, E3) of the rotating machine (16, 16') from the estimated current value, - a sub-step (Etp33) for estimating the internal temperature of the rotating electrical machine (16, 16') using the resistance value (Renroul) of at least one winding (E1, E2, E3).