Abstract:
The invention relates to a method for generating control signals for managing the operation of a synchronous motor with one or more permanent magnets ( 1 ) comprising a stator ( 2 ), the stator comprising a number P of phases ( 3, 4, 5 ), a rotor, the rotor comprising said permanent magnet or magnets, a switching module ( 6 ) provided with a plurality of switches (K 1 -K 6 ), a number N of Hall-effect sensors sensitive to a rotating electromagnetic field induced by said permanent magnet or magnets, N being no lower than 2 and strictly lower than P, the method comprising a step of acquiring status information transmitted by the sensors ( 9, 10 ) and a step of estimating at least one piece of complementary information on the basis of status information transmitted by the sensors ( 9, 10 ), the complementary information characterising the status variation of at least one virtual sensor. The invention also relates to a control device ( 10 ) comprising a module for estimating a piece of complementary information ( 11 ) and a module for generating control signals ( 12 ) configured to implement the method. The invention further relates to an actuator ( 9 ) comprising a synchronous motor with permanent magnets ( 1 ) and a control device ( 10 ).

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The invention relates to the field of actuators equipped with synchronous motors with permanent magnets. The invention in particular pertains to a method for generating control signals for managing the operation of a synchronous motor with one or several permanent magnets equipping such an actuator. The invention also pertains to a control device suitable for carrying out such a method and an actuator comprising a synchronous motor with one or several permanent magnets and a control device. 
       BACKGROUND OF THE INVENTION 
       [0002]    A synchronous motor with permanent magnets generally includes a polyphase stator, made up of one or several coils per phase and a stack of metal sheets making up a magnetic circuit, and a rotor with one or several permanent magnets. Furthermore, in order to determine the angular position of the rotor relative to the coils, sensors are generally positioned on the stator to detect variations of the rotary field induced by the rotor. In practice, these sensors are often angularly offset relative to the coils, for bulk reasons. These sensors in particular deliver information required to be able to generate control signals governing the operation of the motor, but also to determine the position of the rotor (number of revolutions performed, end of travel position, intermediate position, blocked position detection). 
         [0003]    In order to generate the control signals of the motor, it is common practice to position, within the stator of the motor, a number of sensors strictly equal to the number of phases of the stator. For example, in the case of a three-phase stator, three Hall effect sensors are in most cases arranged within the stator. The use of a number of sensors strictly equal to the number of phases of the motor is, however, restrictive in terms of bulk and cost. 
         [0004]    With a view to reducing the number of sensors used to manage the operation of a synchronous motor with permanent magnets, document U.S. Pat. No. 6,163,117 describes a method for generating control signals that makes it possible to decrease the number of sensors. The disclosed principle amounts to replacing one of the actual sensors with a virtual sensor, i.e., generating an output signal of a fictitious sensor by computation, based on signals provided by the real sensors, which are present in a number smaller than the number of phases. It appears, however, that the disclosed control method does not make it possible to generate control signals for the operation of the motor to be optimized. The method in particular does not offer any flexibility to account for the different possible operating ratings of the motor and optimize the operation of the motor in each of these operating ratings. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    The invention seeks to resolve the drawbacks of the state of the art. To that end, proposed according to a first aspect of the invention is a method for generating control signals for managing the operation of a synchronous motor with one or more permanent magnets comprising a stator, the stator comprising a number P of phases, a rotor, the rotor comprising said permanent magnet(s), a switching module provided with a plurality of switches, a number N of Hall effect sensors sensitive to a rotating electromagnetic field induced by said permanent magnet(s), N being no lower than 2 and strictly lower than P, the method comprising:
       a step of acquiring status information transmitted by the sensors; and   a step of estimating at least one piece of complementary information on the basis of status information transmitted by the sensors, the complementary information characterizing the status variation of at least one virtual sensor;   a step consisting of determining an operating stage of the motor; and   a step consisting of generating control signals to act on the switches of the switching module based on the status information, and the at least one piece of complementary information and operating stage of the motor.       
 
         [0010]    By taking into account the operating stage of the motor to generate control signals, the operation thereof is optimized, for example in terms of available torque or in terms of thermal performance or output, including when the number of real sensors is lower than the number of phases of the motor. 
         [0011]    Preferably, the operating stage belongs to a set of possible stages, including at least two stages from among the following stages: an idle stage, a startup stage, a nominal rating stage, a gradual stop stage and an emergency stop stage. 
         [0012]    According to one particularly advantageous embodiment, the operating stage of the motor is determined based on status information transmitted by the Hall effect sensors. The status information transmitted by the Hall effect sensors in particular makes it possible to estimate the direction, speed and acceleration of the motor from the first revolution fractions. 
         [0013]    According to one particularly simple embodiment, the possible stages include:
       a first stage during which the control signals are generated with a first predetermined time shift, zero or nonzero, relative to moments marked by a change in status of one of the Hall effect sensors or the virtual sensor, and   a second stage during which the control signals are generated with a second predetermined time shift different from the first predetermined time shift, zero or nonzero, relative to moments marked by a change in status of one of the Hall effect sensors or the virtual sensor.       
 
         [0016]    This embodiment may in particular be implemented with binary output Hall effect sensors. The first stage may for example be a startup stage, and the second stage a nominal rating stage. 
         [0017]    In practice, the control signals are generated during the first stage such that an electrical current circulating between terminals of a winding of a phase of the stator has a first predetermined electrical phase shift, zero or nonzero, relative to a counter-electromotive force induced across the terminals of the winding by the rotating electromagnetic field. 
         [0018]    During the second stage, the control signals are generated such that the electrical current circulating between the terminals of the winding of the phase of the stator has a second predetermined electrical phase shift, different from the first predetermined electrical phase shift, relative to the counter-electromotive force induced across the terminals of the winding by the rotating electromagnetic field. 
         [0019]    According to one alternative of the invention, the possible stages include the nominal rating stage, during which the step of estimating at least one piece of complementary information comprises:
       a step of measuring time intervals between two successive status changes of one of the Hall effect sensors;   a step for computing the mean duration of these intervals; and   a step consisting of using the computed mean duration to estimate at least one piece of complementary information.       
 
         [0023]    During the nominal rating stage, the control signals are preferably generated such that an electrical current circulating between terminals of a winding of a phase of the stator has a first predetermined electrical phase shift, zero or strictly less than 15° relative to a counter-electromotive force induced by the rotating electromagnetic field across the terminals of the winding. In the nominal rating, this control strategy makes it possible to optimize the torque and output, and to minimize heat losses. 
         [0024]    According to another feature of the invention, the possible stages include the startup stage, and the step of estimating at least one piece of complementary information comprises, during the startup stage:
       a step of measuring a duration of a time interval between a status change of a first of the Hall effect sensors and an opposite first status change of a second of the Hall effect sensors that follows the status change of the first of the Hall effect sensors or a duration of a time interval between a status change of the second of the Hall effect sensors and an opposite first status change of the first of the Hall effect sensors that follows the status change of the second of the Hall effect sensors; then   a step consisting of using the measured duration to estimate at least one piece of complementary information.       
 
         [0027]    This feature allows greater reactivity during accelerations or decelerations of the motor. 
         [0028]    In practice, the control signals are generated during the startup stage such that an electrical current circulating between terminals of a winding of a phase of the stator has a predetermined electrical phase shift of at least 15° and preferably at least 30° relative to a counter-electromotive force induced across the terminals of the winding by the rotating electromagnetic field. This operating mode makes it possible to obtain a significant flux in the magnetic circuit of the stator of the motor, which makes it possible to guarantee a good start up. 
         [0029]    According to another alternative of the invention, the step of estimating at least one piece of complementary information comprises:
       a step consisting of analyzing status information comprising at least one test to determine whether the status information transmitted by the sensors meets a predetermined sufficiency condition; then   if the sufficiency condition is met, a step consisting of deriving the at least one piece of complementary information directly from the analysis;   or, if the sufficiency condition is not met, a step consisting of choosing the at least one piece of complementary information arbitrarily, then deciding, based on status information received later during a time interval with a predefined duration, whether at least one piece of complementary information must be modified.       
 
         [0033]    Alternatively, the step of estimating at least one piece of complementary information comprises:
       a step consisting of analyzing status information comprising at least one test to determine whether the status information transmitted by the sensors meets a predetermined sufficiency condition; then   if the sufficiency condition is met, a step consisting of deriving the at least one piece of complementary information directly from the analysis;   or, if the sufficiency condition is not met, a step consisting of determining the at least one piece of complementary information based on the analysis and a rotation direction of the motor.       
 
         [0037]    According to one preferred embodiment, P=3 and N=2. The method for generating control signals according to the invention therefore advantageously applies to the motor comprising a three-phase stator. 
         [0038]    According to another aspect of the invention, it pertains to a device for controlling a synchronous motor with permanent magnets, which comprises a module for estimating at least one piece of complementary information and a module for generating control signals that are configured to carry out the method previously described. 
         [0039]    According to still another aspect of the invention, it pertains to an actuator comprising a synchronous motor with permanent magnets comprising a stator, the stator comprising a plurality of windings making up a number P of phases, P being no lower than 2, a rotor, the rotor comprising a number A of permanent magnets, A being greater than or equal to 1, a switching module provided with a plurality of switches, a number N of Hall effect sensors, the Hall effect sensors being sensitive to a rotating electromagnetic field induced by the permanent magnets, N being no lower than 1 and strictly lower than P, the actuator comprising a control device as previously defined, connected to the Hall effect sensors and the switching module  6 . 
         [0040]    Advantageously, the Hall effect sensors are arranged on a shared electronic circuit support element positioned within the stator, the shared support element preferably being in the shape of a disc, disc segment, ring or ring segment. Such a configuration is particularly suitable for a tubular motor widely used for example in the home automation field. 
         [0041]    In order to provide a certain degree of flexibility in choosing the positioning of the sensors within the motor, it is possible to provide that the shared support element comprises a plurality of housings, and preferably a number P of housings, each of the housings being suitable for receiving a Hall effect sensor. Preferably, the shared support element comprises three housings and two Hall effect sensors. According to one embodiment, the housings are arranged at angular intervals of 60° or 120° around a rotation axis of the rotor. 
         [0042]    According to one preferred embodiment, the Hall effect sensors are binary output Hall effect sensors. Alternatively, the Hall effect sensors are analog output Hall effect sensors, connected to a post-treatment stage delivering binary signals. 
         [0043]    According to one preferred embodiment, the number A is equal to two or four. 
         [0044]    According to another aspect, the invention relates to a method for generating control signals for managing the operation of a synchronous motor with one or more permanent magnets comprising a stator, the stator comprising a number P of phases, a rotor, the rotor comprising said permanent magnet(s), a switching module provided with a plurality of switches, a number N of Hall effect sensors sensitive to a rotating electromagnetic field induced by said permanent magnet(s), N being no lower than 2 and strictly lower than P, the method comprising:
       a step of acquiring status information transmitted by the sensors; and   a step consisting of determining an operating stage of the motor; and   a step consisting of generating control signals to act on the switches of the switching module based on the status information, the operating stage of the motor, and at least one piece of complementary information characterizing the evolution of the status of at least one virtual sensor, and obtained based on status information sent by the sensors during an estimating step, including:   a step consisting of analyzing status information comprising at least one test to determine whether the status information transmitted by the sensors meets a predetermined sufficiency condition; then   if the sufficiency condition is met, a step consisting of deriving the at least one piece of complementary information directly from the analysis;   or, if the sufficiency condition is not met, a step consisting of choosing the at least one piece of complementary information arbitrarily, then deciding, based on status information received later during a time interval with a predefined duration, whether at least one piece of complementary information must be modified.       
 
         [0051]    It is of course possible to combine different aspects or embodiments of the invention with one another to define others. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0052]    Other features and advantages of the invention will emerge from reading the following description, in reference to the appended figures, which illustrate: 
           [0053]      FIG. 1 , a diagrammatic view of an actuator according to the invention; 
           [0054]      FIG. 2 , a diagrammatic view of a shared circuit support element of the synchronous motor with permanent magnets of an actuator according to the invention; 
           [0055]      FIG. 3 , a diagrammatic view of status signals from Hall effect sensors of a synchronous motor with a three-phase stator of the state of the art; 
           [0056]      FIG. 4 , a first diagrammatic view of status signals of the sensors during the implementation of the method for generating control signals according to the invention; 
           [0057]      FIG. 5 , a second diagrammatic view of status signals of the sensors during the implementation of the method for generating control signals according to the invention; 
           [0058]      FIG. 6A , a third diagrammatic view of status signals of the sensors during the implementation of the method for generating control signals according to the invention; 
           [0059]      FIG. 6B , a fourth diagrammatic view of status signals of the sensors during the implementation of the method for generating control signals according to the invention; 
           [0060]      FIG. 7 , a fifth diagrammatic view of status signals of the sensors during the implementation of the method for generating control signals according to the invention; 
           [0061]      FIG. 8 , a diagrammatic view of operating signals of a synchronous motor with a three-phase stator, in the startup and acceleration phase; 
           [0062]      FIG. 9 , a diagrammatic view of operating signals of a synchronous motor with a three-phase stator, in the nominal rating with a constant rotation speed. 
       
    
    
       [0063]    For greater clarity, identical elements are identified using identical reference signs in all of the figures. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0064]      FIG. 1  diagrammatically shows an actuator  10  according to the invention. The actuator  10 , which is intended to drive the piece of home automation equipment, for example a protective or concealing screen, comprises a synchronous motor  12  with permanent magnets, a switching module  14  of the motor and a control device  16  that is connected to sensors  18 ,  20  and the switching module  14 . 
         [0065]    The motor  12  is made up of a stator  22  comprising a stack of metal sheets (not shown) forming a magnetic circuit, and windings  24  forming three phases  26 ,  28 ,  30  arranged at 120° from one another, and a rotor  32  with two permanent magnets  34 ,  36 . 
         [0066]    In a known manner, the switching module  14  includes a plurality of power switches (K 1 -K 6 ), which, based on received control signals, sequentially power the phases  26 ,  28 ,  30  of the motor so as to create a rotating magnetic field. The control sequences are generated based on the relative position of the rotor  32  with respect to the windings  24  of the stator  22 . Thus, the position of the switches (K 1 -K 6 ) at a given moment constitutes a control which, via the phases  26 ,  28 ,  30  of the motor  12 , determines its operation. 
         [0067]    The switching module  14  is controlled by the control device  16 , which comprises a module  38  for estimating the output signal of a virtual sensor and a module  40  for generating control signals  42 . Each of these modules comprises hardware and software means arranged and configured so that the control device  16  implements the method for generating control signals to manage the operation of the motor, as will be described below. 
         [0068]    The module  38  for estimating the output signal of a virtual sensor is connected to the two Hall effect sensors  18 ,  20  positioned stationary relative to the stator  22 , preferably integrated therewith. Preferably, these sensors  18 ,  20  are binary output Hall effect sensors. Preferably, these sensors are positioned at 120° or 60° from one another within the stator  22 . 
         [0069]    As will be described later, the estimating module makes it possible to estimate, from status signals S 1 , S 2  of the two real sensors  18  and  20 , a signal S 3  as would be delivered by a third sensor angularly offset relative to the real sensors  18  and  20 . This signal generated by the estimating module  11  thus characterizes the evolution of the status of a fictitious sensor which, unlike the real sensors  18 ,  20 , is qualified in the present application as a virtual sensor. 
         [0070]    Thus, while three sensors are normally needed for a complete determination of the control signals  42  and the position of the rotor  32  for a motor provided with a three-phase stator, the motor  12  of the actuator  10  according to the invention comprises only two so-called real sensors  18 ,  20 . The method that will be described in detail below therefore makes it possible to generate control signals  42  to act on the switches K 1  to K 6  of the switching module  14  of the motor starting from signals S 1 , S 2  provided by only two real sensors  18  and  20 , and going through an intermediate step for building a signal S 3  of a virtual sensor, from the signals S 1  and S 2 . 
         [0071]      FIG. 2  diagrammatically illustrates a shared support element  44  arranged within the stator  22  of the motor  12  and on which the sensors  18 ,  20  are positioned. The shared support element  44  is substantially planar and is preferably in the shape of a ring segment, as shown in  FIG. 2 . This shape is particularly advantageous in terms of bulk, in particular for a tubular motor. Alternatively, the shared support element  44  may assume the form of a ring, disc or disc segment. The shared support element  44  comprises three housings  46 ,  48 ,  50 , all suitable for receiving a sensor. The first sensor  18  is arranged in a first housing  46 , the second sensor  20  is arranged in a second housing  48 , while a third housing  50  is used in the design phase to house a third real sensor, and validate the method for generating control signals, and during the operating phase to house the connector technology for the two sensors  18 ,  20 . 
         [0072]    For a better understanding of the description of the method according to the invention,  FIG. 3  illustrates the signals delivered by three sensors arranged in a conventional synchronous motor with permanent magnets with a three-phase stator. These binary signals are phase-shifted relative to one another. The corresponding truth table is established below: 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Signals 
               
             
          
           
               
                   
                 Moment 
                 S1 
                 S2 
                 S3 
               
               
                   
                   
               
               
                   
                 T1 
                 0 
                 0 
                 1 
               
               
                   
                 T2 
                 0 
                 1 
                 1 
               
               
                   
                 T3 
                 0 
                 1 
                 0 
               
               
                   
                 T4 
                 1 
                 1 
                 0 
               
               
                   
                 T5 
                 1 
                 0 
                 0 
               
               
                   
                 T6 
                 1 
                 0 
                 1 
               
               
                   
                   
               
             
          
         
       
     
         [0073]    To eliminate one of the sensors, the method according to the present invention includes an estimating algorithm, illustrated by  FIGS. 4 to 7  and executed by the estimating module  38 , which makes it possible to estimate the signal S 3  characterizing the evolution of the status of a virtual sensor based on the status signals S 1  and S 2  transmitted by the real sensors  18  and  20 . The signals S 1 , S 2  from the real sensors and the signal S 3  resulting from the estimating algorithm next feed an algorithm for generating control signals, executed by the module  40  as described in relation to  FIGS. 8 and 9 , which makes it possible to determine the moments at which the control signals are sent to the switching module  14 . 
         [0074]    The algorithm for estimating the signal S 3  can be divided into three successive phases, namely an initialization phase implemented upon startup, when the motor leaves an idle stage, followed by an acceleration phase during which the speed of the motor is not constant, lastly followed by a constant speed phase corresponding to a nominal rating. If applicable, the estimation of the signal S 3  in a later deceleration phase may follow the same algorithm as in the constant speed phase. 
         [0075]    During the initialization phase, the goal is to determine, with very little available data, an initial value of the signal S 3  from the virtual sensor. In this phase, the observations made on the preceding truth table are used: upon reading this table, one can see that when both sensors  18  and  20  have the same status (for example, sensor  18  and sensor  20  with the same status “00” or “11”), then the third sensor necessarily has the opposite status. This first observation makes it possible to determine the status signal S 3  of the third sensor, here the virtual sensor, when the status signals S 1 , S 2  of the two real sensors  18  and  20  are identical. 
         [0076]    A first embodiment of the algorithm for this initialization phase is illustrated in  FIGS. 4 and 5 , where the evolutions as a function of time are shown of the signals S 1  and S 2  of the real sensors  18  and  20  and the reconstituted signal S 3  from the virtual sensor. 
         [0077]      FIG. 4  illustrates a case in which the initial status of the signals S 1  and S 2  does not leave any choice regarding the value of the signal S 3 . The signals S 1  and S 2  initially being at  0  when the motor is stopped (moment  10 ), the signal S 3  has been positioned at  1  (only compatible value according to the truth table). When the motor is started up, the rotation of the motor first drives a status change of the signal S 1  at moment  11 . The new status of the signals S 1  and S 2 , i.e., “1” and “0”, being compatible with the preceding value of S 3  (“1”), the latter is retained. Then the signal S 2  changes status in turn at moment  12 , and the preceding value of the signal S 3  becomes incompatible with the new status of the signals S 1  and S 2 . The module for estimating the output signal of a virtual sensor  38  then modifies the value S 3 , which completes this initialization phase. 
         [0078]      FIG. 5  illustrates a situation in which the initial values of the signals S 1  and S 2  do not make it possible to unambiguously determine the signal S 3  at the same moment. The status of the virtual sensor is first determined arbitrarily from among the statuses compatible with the statuses of the real sensors  18  and  20  (for example at moment  13  in  FIG. 5 ), then this arbitrary status is next maintained for a time interval with a predetermined duration. If, during this time interval, the status signals S 1  and S 2  transmitted by the real sensors do not show any variation, the status S 3  of the virtual sensor is modified (here at moment  14  in  FIG. 5 ). This process is carried out in a loop for a certain length of time. Advantageously, it is possible to consider varying the duration of the time interval based on a desired startup direction, a temperature or initial conditions. Similarly to the first embodiment, the initialization phase finishes upon the first status change of one of the signals S 1  and S 2 , which, following an incompatibility with the current signal S 3 , causes a modification of the status of the latter, here at moment  15  identified in  FIG. 5 . 
         [0079]    According to a second embodiment of the algorithm implemented in the initialization phase, illustrated in  FIGS. 6A and 6B , the status of the virtual sensor is determined by the computation based on the values of the real sensors and the known predetermined rotation direction. To implement this embodiment, the motor should have previously saved sequences of values of the signals S 1 , S 2  from the real sensors corresponding to the rotation directions. These sequences can be predefined or learned during an installation step. In the case illustrated in  FIG. 6A , the motor is powered so as to rotate in the counterclockwise direction. In the presence of a signal S 1  assuming the value “0” and a signal S 2  assuming the value “0” at the initial moment of the stop, the algorithm initially gives the value “1” to S 3  (only compatible value according to the truth table), then, after the first observed status change (here the transition to the value “1” of the signal S 2 ), the evolution of the signal S 3  is estimated by a value assigned to the signal S 3  and a transition moment, when the signal actually assumes the assigned value. This assigned value depends on the rotation direction, and therefore the next sequences for the values of the signals S 1 , S 2 . In the illustrated example, the sequence (0,1) of the signals S 1 , S 2  is followed by a sequence (1,1). The value assigned to S 3  is therefore 0. The algorithm generates a transition to the value “0” of the signal S 3  simultaneously with the transition of the signal S 2  (not shown), or after a time delay ΔT (as illustrated by  FIG. 6A ). The value assigned to S 3  during a sequence change of the signals S 1 , S 2  and the potential delay ΔT of the transition of signal S 3  relative to the transition of signal S 2  results from prior learning.  FIG. 6B  illustrates a case where the motor is powered in the clockwise direction. Initially, the signals S 1  and S 2  are in state “1”, which imposes state “0” on S 3 . As a result of the first transition of the signal S 1 , the sequence of signals S 1 , S 2  becomes (0,1). Contrary to the example illustrated in  FIG. 1 , the following sequence for the signals S 1 , S 2  is (0,0) in the considered rotation direction. The value assigned to S 3  is therefore 1, and the transition is triggered either simultaneously with the transition of the signal S 1 , or after a time delay ΔT. The sequences of the values of the signals S 1 , S 2 , coming from the real sensors, as well as the time delay duration must have been subject to prior learning for each rotation direction. 
         [0080]    The initialization phase is followed by the acceleration phase, during which the status of the virtual sensor is determined, for a given rotation direction, also taking into account the time elapsed since the last transition of a signal from a real sensor, as illustrated in  FIGS. 4 and 7 . The estimating module  38  first measures the duration TM between a rising edge (transition from the low state or “0” to the high state of or “1”) of a first of the sensors A and B and a falling edge (transition from the high state or “1” to the low state or “0”) of the other of the sensors A and B to generate, after a length of time equal to TM from the falling edge of the other real sensor, a rising edge of the signal of the virtual sensor. Thus, at moment  12 ′ in  FIG. 4 , a transition of the signal S 1  is observed. The duration TM between moments  12  and  12 ′ is stored as time delay value to generate, at a moment  12 ″, after  12 ′ by a time equal to TM, a new status change of S 3 . A similar transition is illustrated in  FIG. 7 . Then, secondly, the estimating module  11  measures the duration TD ( FIG. 7 ) between the following falling edge of the first of the sensors A and B and the rising edge of the other of the sensors A and B to generate, after a length of time equal to TD from the rising edge of the other real sensor, a falling edge of the signal of the virtual sensor. The construction of the virtual signal by the estimating module  38  thus continues, closer and closer. The acceleration phase continues as long as the rotation speed varies monotonously, therefore for example as long as the time interval between two successive status changes of the signal S 1  decreases. The advantage of this method for determining the signal characterizing the status of the virtual sensor is that it allows high reactivity during acceleration phases. 
         [0081]    The acceleration phase is followed by a nominal rating phase, during which the signal characterizing the status of the virtual sensor is determined taking into account the duration of the time intervals between two successive status changes of one or the other of the real sensors. In particular, by computing the mean duration of these intervals, it is possible to predict that, by analogy, the status changes of the virtual sensor must follow one another at regular time intervals with a duration substantially identical to the mean duration. 
         [0082]    As shown by the elements above, the algorithm for generating the signal S 3  makes it possible to reconstruct the signal characterizing the status of a virtual sensor from information provided by the real sensors. 
         [0083]    Based on status signals from the real sensors and the reconstituted signal from the virtual sensor, the second algorithm, illustrated in  FIGS. 8 and 9 , is intended to determine the moments at which the control signals are sent, and more generally to allow the establishment of the control signals to act on the switches of the switching module  14 . These moments are in particular determined taking into account the operating state of the motor (idle, startup, acceleration, nominal rating, deceleration, emergency stop, etc.). The passages to the startup, gradual stop or emergency stop stages are done upon order from the user or detection of an anomaly. However, the passage from the startup stage to the nominal rating stage is done based on evolution criteria of the position of the rotor. 
         [0084]      FIG. 8  illustrates the operating signals of the synchronous motor with permanent magnets with a three-phase stator in the acceleration phase at the startup moment, and  FIG. 9  shows the corresponding signals in the nominal rating at a constant speed, based on the signals S 1  and S 2  of the real sensors  18  and  20  and the signal S 3  computed by the estimating module  38 . The top part of each of  FIGS. 8  in  9  illustrates the status signals S 1 , S 2 , S 3 . The following six curves illustrate the evolution of the status of each of the switches (K 1  to K 6 ) induced by the status signals of the sensors as a function of time. The bottom part of each figure lastly illustrates the corresponding phase voltage U 1 , U 2 , U 3  (stair step functions) and the electromotive force FEM 1 , FEM 2 , FEM 3  induced across the terminals of each of the phases (smoothed functions). It should be noted that the phase current is substantially in phase with the phase voltage. 
         [0085]    In the startup and acceleration stages, in  FIG. 8 , when the rotation speed increases from the stop to a nominal value, the switching, i.e., the sending, by the generating module  40  integrated into the control device  16 , of control signals controlling the switching of the switches K 1  to K 6  of the switching module  14 , is synchronized so as to ensure a sufficient predetermined phase shift between the electric current traversing a stator winding (or the phase voltage, current and voltage being substantially in phase) and the counter-electromotive force FEM 1 , FEM 2 , FEM 3 , i.e., the voltage induced across the terminals of this same winding by the moving magnets. More specifically, one can see in the example of  FIG. 8  that for each phase, the voltage across the terminals of the windings of the phase (periodic or quasiperiodic stair step function) is phase-shifted relative to the electromotive force induced by the permanent magnets (in the case at hand, with a phase delay of about 1/12th of the time period of the voltage). 
         [0086]    The goal during this phase is to guarantee the startup and maximize the torque, even if it means temporarily deteriorating the speed, increasing the intensity of the current and the dissipated heat. In practice, and taking into account the physical angular shift existing between the fixed sensors  18  and  20  and the windings  24 , this result is obtained in this embodiment by synchronizing the switching of the switches on the output edges of the signals of the real sensors  18  and  20  and the virtual sensor. In other words, the control signals are sent at the moments marked by a status change of one of the real sensors or the virtual sensor. However, let us add that this perfect synchronism is only encountered if the angular positioning of the fixed sensors  18  and  20  relative to the windings  24  has been chosen carefully. More generally, for any angular positioning, it will be noted that the desired phase shift in the startup and acceleration phase between voltage across the terminals of the windings of a phase and electromagnetic force induced by the permanent magnets in these same windings corresponds to a predetermined phase shift D 1 , zero or nonzero, between the switchovers of the switches K 1  to K 6  and the status changes of the sensors. 
         [0087]    The corresponding truth table, in a given rotation direction, is established below: 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 Truth Table 
               
             
          
           
               
                   
                 Signals 
                 Activation with a phase shift D1 (zero) 
               
             
          
           
               
                 Moment 
                 S1 
                 S2 
                 S3 
                 K1 
                 K2 
                 K3 
                 K4 
                 K5 
                 K6 
               
               
                   
               
               
                 T1 
                 0 
                 0 
                 1 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
               
               
                 T2 
                 0 
                 1 
                 1 
                 0 
                 1 
                 0 
                 1 
                 0 
                 0 
               
               
                 T3 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 1 
                 0 
                 0 
               
               
                 T4 
                 1 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 1 
                 0 
               
               
                 T5 
                 1 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
               
               
                 T6 
                 1 
                 0 
                 1 
                 1 
                 0 
                 0 
                 0 
                 0 
                 1 
               
               
                   
               
             
          
         
       
     
         [0088]    In the nominal rating, in  FIG. 9 , when the rotation speed is constant and equal to the nominal speed, the synchronization is done such that the voltage in the windings  24  is in phase with the counter-electromotive force, which limits the flow in the magnetic circuit, therefore the heating and losses. 
         [0089]    In practice, in the example illustrated in  FIG. 9 , this operating mode is obtained by a phase shift D 2  of the switches K 1  to K 6  relative to the status signals S 1 , S 2  and S 3  of the real and virtual sensors, different from the phase shift D 1  encountered in the startup and acceleration phase. More specifically and as an illustration,  FIG. 8  shows a phase delay of one twelfth of the period of the voltage signal. The corresponding activation table is established below: 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 Activation table 
               
             
          
           
               
                   
                 Signals 
                 Activation with a phase shift D2 
               
             
          
           
               
                 Moment 
                 S1 
                 S2 
                 S3 
                 K1 
                 K2 
                 K3 
                 K4 
                 K5 
                 K6 
               
               
                   
               
               
                 T1 
                 0 
                 0 
                 1 
                 0 
                 1 
                 0 
                 1 
                 0 
                 0 
               
               
                 T2 
                 0 
                 1 
                 1 
                 0 
                 0 
                 1 
                 1 
                 0 
                 0 
               
               
                 T3 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 1 
                 0 
               
               
                 T4 
                 1 
                 1 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
               
               
                 T5 
                 1 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 0 
                 1 
               
               
                 T6 
                 1 
                 0 
                 1 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
               
               
                   
               
             
          
         
       
     
         [0090]    In summary, the control signals are generated with a zero or nonzero time shift relative to the moments marked by a status change of one of the sensors  18  or  20  (signals S 1  and S 2 ) or the virtual sensor (signal S 3 ), which at least assumes a first value D 1  in the startup and/or acceleration phase, and a second value D 2  in the nominal rating, depending on whether one wishes to maximize the reactivity of the system (upon startup) or the output (in the nominal rating). 
         [0091]    In practice, the time shift applied to send control signals is determined in the startup stage and the nominal rating, based on the number of permanent magnets  34 ,  36 , an angle defined by the position of a first sensor  18  and the position of a second sensor  20  adjacent to the first sensor and an angle defined by the position of the first sensor  18  and the position of the phase  30 , i.e., the winding, with which it is associated. 
         [0092]    Of course, various alternatives are possible. It is in particular possible to provide a continuous variation of the phase shift between phase voltage and the switches of the sensors when the rotation speed increases, such that the phase shift between phase voltage and induced counter-electromotive force decreases continuously when the speed increases. It is also possible to use a variation by plateaus. The rotation speed can be estimated simply by the time separating two status changes of a same sensor  18  or  20 . This evolution is reflected in the second process by a continuous variation of the time shift between the status changes of the signals S 1 , S 2  and S 3 , and the switching orders K 1  to K 6 . 
         [0093]    Although for clarity reasons, the above description limited itself to the case of a stator comprising three phases configured in a triangle and a rotor comprising two magnets, the method for generating control signals according to the invention may be implemented for any type of stator-rotor configuration, and in particular a star configuration. In other words, the method according to the invention applies to any type of polyphase stator and irrespective of the number of permanent magnets supported by the rotor.