Device for controlling a continuous-rotation motor

Abstract

The invention relates to a device for controlling a continuous rotation electric machine. A control device (2) for controlling the supply of a continuous rotation electric machine, in particular a direct current type electric machine of a timepiece, is arranged to generate electric pulses with a lower supply voltage to drive the rotor, the number of these electric pulses within each defined time interval being variable, in particular as a function of the load applied to the electric machine. The control device comprises a voltage divider (22A, 22B, 24) arranged to supply said lower supply voltage with a plurality of different values and thus said electric pulses with a variable voltage. A logic circuit (20) is arranged to count the number of electric pulses in successive time periods; to periodically select one voltage value from said plurality of different values as a function of the counted number of electric pulses or of a sequence of counted numbers of electric pulses; and to control the voltage divider so that the voltage divider supplies said lower supply voltage with the selected voltage value after the voltage value has been selected.

Description

Technical Field

[0001] This invention relates to a control device for controlling the power supply to a continuously rotating electric motor. Specifically, this invention relates to an electromechanical timepiece comprising a continuously rotating DC motor and the control device, the continuously rotating DC motor being configured to be incorporated into the timepiece. Background Technology

[0002] European Patent Document No. 3663872 discloses a device for controlling the power supply to a continuously rotating electric motor, particularly for clock applications. The device is arranged to enable it to control the rotation of the motor's rotor by allowing variations in the rotor's speed, which are not sudden and are kept within limits that are conducive to the correct operation of the motor, even under adverse conditions or after a disturbance event. At the same time, it ensures accurate indication of the current time by controlling the average number of rotations per unit time of the rotor over time.

[0003] The aforementioned literature provides various operating modes or states, particularly based on the load driven by the motor at a given time, the motor's operating conditions (especially disturbances experienced by the motor), and the time drift of the number of revolutions performed by the motor from the initial time relative to a given setpoint value of the average speed (corresponding to rotor revolutions per unit time). In one operating mode disclosed in that literature, either "low-energy" electrical pulses are generated or no pulses are generated in each cycle of the rotor speed regulation method. This is the normal operating mode of the motor, i.e., under typical operating conditions without significant disturbances. It should be noted that the present invention primarily relates to such a normal operating mode or state, in which "low-energy" electrical pulses are continuously supplied to the stator of a continuously rotating motor in a variable number for each given time interval to rotate the rotor of the motor.

[0004] To generate “low-energy” electrical pulses as mentioned in European Patent Document 3663872, those skilled in the art can particularly utilize the teachings of European Patent Document 3664280 and European Patent Document 3663871. The former discloses an advantageous method for an electric motor whose stator is formed by two coils and whose rotor is provided with a plurality of permanent magnets (more generally, the permanent magnet poles are magnetically coupled to the stator), and the latter describes a particularly effective voltage divider for dividing a first supply voltage, which is supplied in particular by a battery supplying a supply voltage between 1.2V and 1.5V. Depending on the battery state, the first supply voltage may drop below this range, in the case of generating a series of “low-energy” electrical pulses with a given constant duration, to a smaller voltage (second supply voltage) supplied to the motor stator.

[0005] European Patent Document No. 3663871 aims to reduce the power consumption of a motor by dividing a first supply voltage supplied by a battery into a lower, fixed second voltage applied to the stator terminals. In other words, the current injected into the inductors (coils) of the stator is minimized, and therefore resistive losses are also minimized. For example, the disclosed voltage divider divides the first supply voltage supplied by the battery by three. The choice of a voltage divider dividing by three is based on the maximum value of the induced voltage in the two coils of the stator during normal operation of the motor. Dividing by three provides a margin to keep the electrical pulses driving, i.e., to keep the second supply voltage higher than the maximum induced voltage in the stator, but the difference between the two voltages is much smaller than when the first supply voltage is applied directly to the stator. Summary of the Invention

[0006] The object of the present invention is to provide a control device for controlling the power supply to a continuously rotating motor, which is particularly integrated into a timepiece, and the control device enables the motor to be powered in the most efficient manner possible, while keeping the power consumption of the motor at least minimized in a given operating mode or state.

[0007] This invention relates to a control device for controlling the power supply to a continuously rotating electric motor formed by a stator and a rotor. The stator includes at least one power supply coil, and the rotor carries at least one permanent magnet, which is magnetically coupled to the at least one power supply coil when the rotor rotates. The control device is arranged to be powered by a power supply unit supplying a first power supply voltage, and includes a voltage divider arranged to divide the first power supply voltage and supply a second power supply voltage lower than the first power supply voltage to the stator. The control device is arranged to generate electrical pulses in a given operating mode or state of the motor, the electrical pulses being drive pulses supplied to the stator with the second power supply voltage to drive the rotor. The number of these electrical pulses within each defined time interval is variable, particularly depending on the load applied to the motor. The control device includes logic circuitry arranged to enable it to: - count the number of electrical pulses within a continuous time period; - periodically select a voltage value from the plurality of different values ​​supplied for a second supply voltage based on the count of electrical pulses or a sequence of counts of electrical pulses; and - control a voltage divider such that when an electrical pulse is generated after the selected voltage value, the voltage divider supplies a second supply voltage having the selected voltage value. The logic circuitry is arranged such that, for each new selection:

[0008] - When the last calculated number of electrical pulses or the first increasing function of the last number is lower than a first determined threshold, or when the sequence of calculated numbers of electrical pulses including the last number or the sequence of the first increasing functions of each of these numbers satisfies a first selection criterion, if the value of the second supply voltage is greater than a given low value, the value of the second supply voltage is reduced, with respect to the first selection criterion, at least one number in the number sequence or the first increasing function of the number is lower than the first determined threshold;

[0009] - When the last calculated number of electrical pulses or the first increasing function of the last number is higher than the second determined threshold, or when the sequence of calculated numbers of electrical pulses including the last number or the sequence of the first increasing functions of each of these numbers satisfies the second selection criterion, if the value of the second supply voltage is less than a given high value, the value of the second supply voltage is increased, with respect to the second selection criterion, at least one number in the number sequence or the first increasing function of the number is higher than the second determined threshold.

[0010] In one primary embodiment, the logic circuit is arranged to enable it to determine which of a plurality of determined value ranges the calculated number of electrical pulses, or a first increasing function of that number, or a second function of a sequence of calculated numbers of electrical pulses, or a second function of a sequence of first increasing functions for each of these numbers, lies in, and to enable it to periodically select a voltage value from the plurality of different values ​​provided for a second supply voltage based on the finally determined value range.

[0011] According to a general alternative to this primary embodiment, the plurality of value ranges includes a first value range with the first threshold as an upper limit, a second value range with the second threshold as a lower limit, and a third value range located between the first and second value ranges and with the first and second thresholds as upper and lower limits, respectively. In this general alternative embodiment, the logic circuitry is arranged such that, for each new selection:

[0012] - When the last calculated number of electrical pulses, or a first increasing function of that last number, or a second function of a sequence of calculated numbers of electrical pulses including that last number, or a second function of a sequence of first increasing functions of each of these numbers, is within a first value range, if the value of the second supply voltage is greater than the lower value, then the value of the second supply voltage is reduced.

[0013] - When the last calculated number of electrical pulses, or the first increasing function of that last number, or the second function of the sequence of calculated numbers of electrical pulses including that last number, or the second function of the sequence of the first increasing functions of each of these numbers, is within the second value range, if the value of the second supply voltage is less than the high value, then the value of the second supply voltage is increased.

[0014] - When the last calculated number of electrical pulses, or the first increasing function of that last number, or the second function of the sequence of calculated numbers of that last number of electrical pulses, or the second function of the sequence of the first increasing functions of each of these numbers, is within the range of the third value, the value of the second supply voltage remains at the value obtained in the previous selection.

[0015] In an advantageous embodiment of the invention, the control device includes a measuring circuit arranged to detect and count alternations or periods of induced voltage in the power supply coil or at least one power supply coil as the rotor rotates, each consecutive time period being defined by a given number of consecutive alternations or periods detected in the induced voltage. Logic circuitry is arranged to determine, for each consecutive time period, the ratio of electrical pulses for each alternation or period of the induced voltage, equal to the number of counted electrical pulses in the considered time period divided by the given number of alternations or periods in that time period, the ratio defining a first increasing function of the calculated number of electrical pulses.

[0016] According to a preferred embodiment of the invention, the voltage divider includes a switching circuit arranged between a power supply unit supplying a first supply voltage on one side and a ground wire of a control device on the other side, and the voltage divider is arranged to selectively divide the first supply voltage by a plurality of integers greater than 1.

[0017] In an advantageous alternative to the preferred embodiment, the voltage divider comprises N capacitors C n n = 1 to N, where N is an integer greater than 1. The logic circuit is then arranged to enable it to turn the switches of the switching circuit on and off, so as to generate a series of electrical pulses, each series consisting of S+1 consecutive electrical pulses, where S is an integer chosen between 1 and N, and each series is generated as follows:

[0018] - First, during the pulse duration, the power supply unit supplies a first supply voltage to the first capacitor C1 among the N capacitors connected via the stator, so as to generate the first electrical pulse in the considered pulse series;

[0019] Then, when the quantity S equals 2, during the pulse duration, the stator is connected between capacitor C2 and capacitor C1 to generate a second electrical pulse; or, when the quantity S is greater than 2, each time during the pulse duration, the stator is successively connected to capacitor C1 among the S capacitors included in the N capacitors. J and capacitor C J-1 Between these, J changes from 2 to S, so as to generate S-1 electrical pulses in succession;

[0020] Finally, during the duration of this pulse, the stator is connected to capacitor C. SBetween the ground wire and the ground wire, so as to generate the last electrical pulse in the series of electrical pulses under consideration.

[0021] Each time a new voltage value is selected, the logic circuit can reselect the quantity S. The multiple different values ​​provided for the second supply voltage correspond to multiple voltages defined by dividing the first supply voltage by m, where m = 2 to N+1. Preferably, N capacitors C n (n=1 to N) have essentially the same capacitance. In particular, the quantity N is intended to be between 3 and 6, inclusive.

[0022] It should be noted that, in the given operating mode or state of the motor, for the electrical pulses to be continuously driven, the first supply voltage divided by N+1 is greater than the absolute value of the maximum induced voltage typically generated across the stator.

[0023] In a preferred alternative embodiment, the control device is arranged such that each electrical pulse is generated when the induced voltage across the stator is substantially equal to the maximum induced voltage.

[0024] In a typical alternative embodiment, the electrical pulses have a constant pulse duration during the given operating mode or state of the motor, at least within each time interval spanning several tens of revolutions of the rotor.

[0025] In a typical embodiment, the motor is a DC motor powered by a primary battery or a storage battery.

[0026] In a particular alternative embodiment, the control device is arranged to control the average rotational speed of the motor rotor to be equal to a given setpoint speed.

[0027] The present invention also relates to a timepiece comprising a continuously rotating motor and a means for controlling the power supply to the motor as described above.

[0028] By means of the features of this invention, resistive losses, also known as losses due to the Joule effect, can be optimally reduced. It should be remembered that resistive losses are caused by the fact that current flowing through a conductor generates heat. Joule's first law states that the heating power P generated by an electrical conductor... J It is proportional to the product of its resistance R and the square of its current I, i.e., P J = R x I 2 However, the effective mechanical power P mec It is proportional to the current, not its square. More specifically, the mechanical power P mec = k u × w × I, where k uHere, w is the torque constant, and w is the rotor speed. Therefore, this invention enables a significant reduction in losses due to the Joule effect in the motor, while ensuring proper and safe operation of the motor, i.e., providing sufficient mechanical power, particularly sufficient for the load borne by the motor. This results in very high operating efficiency of the motor, while allowing for minimal reduction in its power consumption. Attached Figure Description

[0029] The invention will now be described in more detail with reference to the accompanying drawings, which are given by way of example only and in no way limiting, wherein:

[0030] - Figure 1 A continuously rotating electric motor and a device for controlling the power supply to the motor are schematically shown.

[0031] - Figure 2 This is a circuit diagram of an alternative to a preferred embodiment of the stator of the continuously rotating electric motor and a device for controlling the power supply to the motor according to the present invention;

[0032] - Figure 3 The induced voltage in each of the two coils of the stator and the measurement signal derived from one of these two induced voltages are shown.

[0033] - Figure 4 This is a table showing the management of the switching circuits of the control device in measurement mode;

[0034] - Figure 5 This is a table showing the management of the switching circuit of the control device in motor drive mode when a positive electrical pulse is generated; and

[0035] - Figure 6 This is a table showing the management of the switching circuit of the control device in the motor drive mode when a negative electrical pulse is generated. Detailed Implementation

[0036] Referring to the accompanying drawings, a preferred embodiment of the control device 2 according to the present invention is described below, which is used to supply power to a continuously rotating DC motor 4, that is, a motor that supplies power at a substantially constant voltage when the stator is powered to rotate the rotor.

[0037] The continuous rotary motor 4 is a small motor, the size of which can be designed to be integrated into a timepiece. For example... Figure 1As shown, the motor 4 includes a coreless stator formed by two power supply coils B1 and B2, and a rotor 6 formed by a shaft. A pinion 8 and two flanges 10 are mounted on the shaft. The pinion 8 defines the power output to a load driven by the motor. The two flanges 10 carry permanent magnets 12a and 12b. These magnets have alternating polarities on the internal space side between the two flanges. The two coils B1 and B2 are partially inserted into this internal space, such that the magnets are magnetically coupled to the stator coils when the rotor rotates.

[0038] Two coils, B1 and B2, are electrically connected to a control device 2, which includes a voltage divider formed by a switching circuit 22 and multiple capacitors 24, a logic circuit 20, and a measurement circuit 18. The switching circuit is arranged between the stator on one side and the ground wire of the power supply unit 16 on the other. The control device is configured to be powered by the power supply unit 16 (particularly a battery), which supplies a first supply voltage V to the control device. dd The voltage divider is arranged so that it can selectively divide the first supply voltage V. dd Divide by multiple integers greater than 1, as will be explained in more detail below.

[0039] exist Figure 2 In the advantageous alternative embodiment shown, the switching circuit 22 includes two switches SA+ and SB+ respectively disposed between the power supply terminal receiving the first power supply voltage of the power supply unit and two terminals 26 and 28 of the stator; a first series of switches 22A respectively disposed between the first terminal 26 of the stator and ground and a plurality of capacitors 24; and a second series of switches 22B respectively disposed between the second terminal 28 of the stator and ground and a plurality of capacitors 24. For small motors, particularly clock-type motors, the switches are typically formed by MOS transistors. In a particular alternative embodiment, the plurality of capacitors are formed by five capacitors C1 to C5. The first series of switches 22A includes six switches SA0, SA1 to SA5, wherein switch SA0 is grounded and the five switches SA1 to SA5 are respectively connected to capacitors C1 to C5. The second series of switches 22B includes six switches SB0, SB1 to SB5, wherein switch SB0 is grounded and the five switches SB1 to SB5 are respectively connected to capacitors C1 to C5.

[0040] The measurement circuit includes two switches SM1 and SM2 (in a typical alternative embodiment, at least one switch is provided), a comparator 18a, and a counter 18b associated with logic circuitry 20. Comparator 18a has two inputs connected to the first and second terminals 27 and 28 of coil B2, respectively, and provides a digital signal Pol_B2 that alternates between its two states "0" and "1" in a substantially periodic manner as the rotor rotates (the digital signal is periodic if the rotor speed is constant). The digital signal Pol_B2 indicates the instantaneous polarity of the induced voltage 32 in coil B2. Further, the induced voltage 30 in coil B1 is shown... Figure 3 In the signal Pol_B2, state "0" corresponds to the negative polarity of the induced voltage 32, while state "1" corresponds to the positive polarity of the induced voltage. The transition between the two states of the digital signal Pol_B2 determines the induced voltage through an intermediate voltage; voltages below this intermediate voltage are defined as the negative polarity of the induced voltage, while voltages above this intermediate voltage are defined as the positive polarity of the induced voltage.

[0041] Switch SM2 allows the electrical connection between the two coils B1 and B2 arranged in series to be temporarily interrupted, and switch SM1 allows the first terminal 27 of coil B2 to be temporarily connected to the reference voltage V. Ref The reference voltage V Ref Determine the intermediate voltage of the induced voltage U in coil B2, which is less than the first supply voltage V. dd (The operation of the measurement mode, referred to as the "measurement mode," is described below.) Counter 18b is arranged to count all transitions between two states in the digital signal Pol_B2, corresponding to the two polarities of the induced voltage U, and thus counting the number of alternations of the induced voltage; or to count all transitions to a given state between two states in the digital signal Pol_B2, and thus counting the number of cycles of the induced voltage.

[0042] The operation of the control device according to a preferred embodiment will be described below. Generally, the voltage divider is arranged to enable it to supply a first supply voltage V. dd Voltage division is performed, and a voltage lower than the first supply voltage (battery voltage V) is supplied to the stator. BatThe second supply voltage. According to the invention, the voltage divider is arranged to supply a second supply voltage having a plurality of different values. The control device according to the invention is then arranged to generate electrical pulses in a given operating mode or state of the continuously rotating motor, these electrical pulses being drive pulses that supply the second supply voltage to the stator to drive the rotor. Therefore, these electrical pulses have variable voltages, which vary according to the criteria set forth below. The number of electrical pulses in each defined time interval is variable, particularly depending on the load applied to the motor. The logic circuit of the control device is arranged to enable it to 1) count the number of electrical pulses in a continuous time interval; 2) periodically select a voltage value from a plurality of different values ​​supplied for the second supply voltage according to the count of electrical pulses or a sequence of the count of electrical pulses; and 3) control the voltage divider such that, after the selected voltage value, the voltage divider supplies a second supply voltage having the selected voltage value when generating electrical pulses. Generally, the logic circuit is arranged such that with each new selection of the voltage value of the second supply voltage:

[0043] - When the last calculated number of electrical pulses or the first increasing function of the last number is lower than a first determined threshold, or when the sequence of calculated numbers of electrical pulses including the last number or the sequence of the first increasing functions of each of these numbers satisfies a first selection criterion, if the value of the second supply voltage is greater than a given low value, the value of the second supply voltage is reduced, with respect to the first selection criterion, at least one number in the number sequence or the first increasing function of the number is lower than the first determined threshold;

[0044] - When the last calculated number of electrical pulses or the first increasing function of the last number is higher than the second determined threshold, or when the sequence of calculated numbers of electrical pulses including the last number or the sequence of the first increasing functions of each of these numbers satisfies the second selection criterion, if the value of the second supply voltage is less than a given high value, the value of the second supply voltage is increased, with respect to the second selection criterion, at least one number in the number sequence or the first increasing function of the number is higher than the second determined threshold.

[0045] Examples of the first and second selection criteria are: 1) The number of electrical pulses or a first increasing function of that number is below a first threshold or above a second threshold in two consecutive time periods. 2) In two of five consecutive time periods, or more generally, in X of X+Y consecutive time periods (where X and Y are non-zero positive integers), the number of electrical pulses or a first increasing function of that number is below a first threshold or above a second threshold.

[0046] In one primary embodiment, logic circuitry is arranged to determine which of a plurality of defined value ranges a calculated number of electrical pulses, or a first increasing function of that number, or a second function of a sequence of calculated numbers of electrical pulses, or a second function of a sequence of first increasing functions for each of those numbers, falls within, and to periodically select a voltage value from the plurality of different values ​​provided for a second supply voltage based on the last determined value range. The aforementioned second function is, for example, the arithmetic mean of a sequence of calculated numbers of electrical pulses, or the arithmetic mean of a sequence of first increasing functions for each of those numbers. In another example, the second function is the maximum value in a sequence of calculated numbers of electrical pulses, or the maximum value in a sequence of first increasing functions for each of those numbers.

[0047] In an advantageous embodiment of the invention, the measuring circuitry of the control device is arranged to detect and count the alternations or periods of induced voltage in the power supply coil or at least one power supply coil as the rotor rotates. Each consecutive time period is defined by a given number of consecutive alternations or periods of induced voltage detected. For example, several alternations or periods provided for a time period substantially correspond to a few seconds or a minute. Typically, the time period has a substantially constant duration, in which case, more specifically, the time period has the same number of alternations or periods of induced voltage. However, in a particular alternative embodiment, the time period can vary. For example, short and long periods can alternate, or the length of the time period can vary based on the results of one or more previous time periods. The time periods can be continuous or periodic with time intervals between them, during which no measurement is performed.

[0048] The logic circuit is then arranged to determine the ratio of electrical pulses for each alternation or cycle of the aforementioned induced voltage for each time period within a continuous time period. By definition, this ratio is equal to the number of electrical pulses counted within the considered time period divided by the given number of alternations or cycles within that time period. This ratio defines a first increasing function of the calculated number of electrical pulses.

[0049] In a particular alternative embodiment, the multiple value ranges include: - a lower range of electrical pulse ratios having a first threshold as an upper limit; - a higher range of the ratios having a second threshold as a lower limit; and - an intermediate range of the ratios having the first and second thresholds as lower and upper limits, respectively. The logic circuitry is arranged such that, with each new selection of the voltage value of the second supply voltage:

[0050] - When the final determined electrical pulse ratio or the second function of the sequence of determined electrical pulse ratios including the final ratio is in a lower range, if the value of the second supply voltage is greater than the lower value, then the value of the second supply voltage is reduced.

[0051] - When the final determined electrical pulse ratio or a second function of the sequence of determined electrical pulse ratios including the final ratio is in the middle range, the value of the second supply voltage is maintained at the value obtained in the previous selection;

[0052] - When the final determined electrical pulse ratio, or a second function of a sequence of determined electrical pulse ratios including the final ratio, is in a higher range, if the value of the second supply voltage is less than the higher value, then the value of the second supply voltage is increased.

[0053] For example, the first threshold is equal to 50%, and the second threshold is equal to 75%, with the intermediate ratio ranging from 50% to 75%.

[0054] In a preferred embodiment, the control device operates alternately in two modes: a "measurement" mode (first mode) and an "electrical pulse generation" mode (second mode). These two modes are managed by logic circuit 20.

[0055] In the alternative embodiment described in the accompanying drawings, the voltage divider includes five capacitors C. n n = 1 to 5, and they have substantially the same capacitance. In the considered motor operating mode or state, the first supply voltage divided by the number of capacitors plus 1 (i.e., divided by 6) is greater than the absolute value of the maximum induced voltage typically generated across the stator. The control device is arranged such that when the induced voltage across the stator is substantially equal to the maximum induced voltage, particularly when the induced voltage in coil B2 is substantially equal to U in absolute form... Max At that time, each electrical pulse is generated (see Figure 3 It should be noted that during the intervals between electrical pulses, the control device is set to "measurement" mode so as to be able to determine the induced voltage U in coil B2 after passing through the reference voltage V. Ref The control unit only enters the "electric pulse generation" mode when each drive electrical pulse is generated to rotate the motor rotor. Therefore, the "electric pulse generation" mode is activated to generate each electrical pulse, and the "measurement" mode is activated at least when the induced voltage in coil B2, which generates the digital signal Pol_B2, approaches the reference voltage V. Ref It is activated at that time, and remains activated until the induced voltage reaches and slightly exceeds the reference voltage, more specifically, at least until a conversion of the digital signal Pol_B2 associated with the event occurs.

[0056] The logic circuit is then arranged to enable it to turn the switch of switching circuit 22 on and off, thereby generating a series of electrical pulses, each series consisting of S+1 consecutive electrical pulses, where S is an integer chosen between 1 and N, and N is the number of capacitors, which is equal to 5 in the alternative embodiment shown. It should be noted that the switch (transistor) is on when open and off when closed. The description of the "electrical pulse generation" mode... Figure 5 and Figure 6 In the table, a cross indicates that the corresponding switch / transistor is on / conducting, while no cross indicates that the corresponding switch / transistor is off / not conducting. The same principle applies to the "Measurement" mode. Figure 4 The table in the document.

[0057] The logic circuit controls the switching circuit 22 to generate each series of electrical pulses as follows:

[0058] First, the power supply unit 16 is connected to the first capacitor C1 of the five capacitors C1 to C5 via the stator during one pulse duration, and the power supply unit 16 supplies a first supply voltage V to it. dd This generates the first electrical pulse in the considered pulse series. Figure 5 and Figure 6 Phase 1 of each possible pressure division listed in the table).

[0059] Then, when the number S equals 2 (divided by 3), the stator is connected between capacitor C2 and capacitor C1 for one pulse duration to generate a second electrical pulse (stage 2, divided by 3); or, when the number of selected capacitors S is greater than 2 (depending on whether the number of capacitors S used is chosen to be equal to 3, 4, or 5, divided by 4, 5, or 6 respectively), the stator is successively connected to S determined capacitors C1 to C1 for one pulse duration. S Capacitor C in J and capacitor C J-1 Between these, J changes from 2 to S in order to generate S-1 electrical pulses in succession (stage 3 divided by 4; or stage 3 and stage 4 divided by 5; or stage 3, stage 4 and stage 5 divided by 6; each stage corresponds to generating one electrical pulse).

[0060] Finally, during the duration of one pulse, the stator is connected to capacitor C. S Between and ground, so as to generate the last electrical pulse in the considered series of electrical pulses ( Figure 5 and Figure 6 (The last stage in each possible voltage divider listed).

[0061] Each time a new second supply voltage value is selected, the logic circuit can reselect the quantity S. It should be noted that... Figure 5 The table in the table relates to logic circuitry controlling switch circuit 22 and two measuring switches SM1 and SM2 to generate positive pulses, which are provided when the induced voltage in the stator is positive, preferably close to the maximum positive voltage of that induced voltage. Figure 6 The table in the table relates to logic circuitry controlling switch circuit 22 and two measuring switches SM1 and SM2 to generate negative pulses, which are provided when the induced voltage in the stator is negative, preferably close to the maximum negative voltage of the induced voltage. It should be noted that, for the selected value S, positive and negative pulses can be generated alternately in a continuous phase, such that electrical pulses can be generated not only during alternations of positive or negative induced voltages, but also during alternations of both positive and negative voltages.

[0062] The truly remarkable aspect of the voltage divider and the method used to control it to generate drive electrical pulses is the rapid establishment of a steady state in which the voltage differences between the first two terminals (located on the stator side) of all the S selected capacitor pairs simultaneously connected to the two stator terminals 26 and 28 are substantially equal. These voltage differences are also substantially equal to the difference between the supply voltage Vdd and the voltage at the first terminal of capacitor C1, and substantially equal to the voltage at capacitor C1. S The difference between the voltage at the first terminal and the ground (the voltage defined by the ground). Therefore, in this steady state, the pulses in each series of electrical pulses are generated with the same selected, predetermined voltage. During the generation of the drive electrical pulses, multiple different possible values ​​of the stator's supply voltage correspond to the supply voltage V. dd Divided by multiple voltages defined by m, where m = 2 to N+1, m is defined as equal to S+1. Multiple different values ​​of the second supply voltage (which are applied to the stator of the motor to generate at least one series of electrical pulses, preferably several consecutive series of electrical pulses) are therefore each equal to V. dd / (S+1), where S is an optional number of capacitors used in the voltage divider, which can vary between 1 and N (the number of capacitors 24) to divide the supply voltage V during a series of S+1 electrical pulses. dd Divide by S+1. Therefore, this provides a very efficient voltage divider that allows the generation of drive electrical pulses with variable and selectable voltages, which, in the preferred embodiment described in detail herein, can be varied and selected according to the range of electrical pulse ratios generated by each alternation or cycle of the induced voltage in the stator.

[0063] Figure 4The table shows the switches (marked with crosses) that are turned on during the measurement mode (“measurement” mode) that occurs between electrical pulses, particularly between each pair of consecutive electrical pulses. At the start of the measurement mode, switch SM2 is off (not conducting) and switch SM1 is on (conducting). At the end of the measurement mode, switch SM1 is off and switch SM2 is on, causing the two stator coils to be connected in series again. This is distinguished by the voltage division provided for the supply voltage (divided by S+1, where S equals 1 to N=5), so as to obtain a voltage substantially equal to or as close as possible to V by using the voltage available at the first terminal of the capacitor. dd / 2 reference voltage V Ref .

[0064] Typically, in the preferred embodiments described above, the electrical pulses have a constant pulse duration. However, in a particular alternative embodiment, the electrical pulses have a constant pulse duration over each time interval, which spans several tens of revolutions of the rotor 6. Therefore, in this particular alternative embodiment, by changing the duration of the electrical pulses in addition to changing the voltage supplied to the stator, the amount of electrical power supplied to the motor is intended to be altered. This also allows for limiting the value of the supply voltage applied to the stator, and thus limiting resistive losses in the motor. In this alternative embodiment, the logic circuitry controlling the generation of the electrical pulses takes into account the change in the pulse duration when managing the voltage divider, particularly for counting and / or grading determined parameters used to select the voltage division level of the voltage divider based on comparable elements.

[0065] In embodiments particularly suited to the control device according to the invention, the control device is arranged to control the average rotational speed of the motor rotor at a given setpoint speed. Specifically, this speed control is implemented in a manner similar to that described in European Patent Document No. 3663872.

[0066] The present invention also relates to a timepiece, particularly a wristwatch, comprising a continuously rotating DC motor and means for controlling the power supply to the motor according to any embodiment of the control device according to the present invention.

Claims

1. A control device (2) for controlling the supply of electrical power to a continuous rotation electric machine (4) formed by a stator and a rotor (6), the stator comprising at least one supply coil (Bl, B2) and the rotor carrying at least one magnet (12a, 12b) arranged to magnetically couple with said at least one supply coil when the rotor is rotating, the control device being arranged to be supplied with electrical power by a supply unit (16) supplying a first supply voltage (Vdd) and comprising a voltage divider (22, 24) arranged to enable it to divide the first supply voltage and supply a second supply voltage lower than the first supply voltage to the stator, the control device being arranged to enable it to generate electrical pulses in a given operating mode or state of the electric machine, said electrical pulses being drive pulses supplied to the stator at said second supply voltage in order to drive the rotor, the number of these electrical pulses per defined time interval being variable as a function of the load applied to the electric machine; characterized in that, The voltage divider (22, 24) is arranged so as to enable it to supply said second supply voltage with a plurality of different values and thus said electrical pulses with a variable voltage; in that the control device (2) comprises a logic circuit (20) arranged so as to enable it to count the number of electrical pulses in successive time periods; to enable it to periodically select a voltage value from among said plurality of different values provided for the second supply voltage as a function of the counted number of electrical pulses or of a sequence of counted numbers of electrical pulses; and to enable it to control the voltage divider so that, when an electrical pulse is generated after the selection of this voltage value, the voltage divider supplies the second supply voltage with the selected voltage value; and in that the logic circuit is arranged so that, for each new selection: - when the last counted number of electrical pulses or the first increasing function of this last number is lower than a first determined threshold, or when a sequence of counted numbers of electrical pulses including this last number or a sequence of first increasing functions of each of these numbers meets a first selection criterion, according to which at least one of the numbers of the sequence or the first increasing function of this number is lower than a first determined threshold, the value of the second supply voltage is decreased if this value is greater than a given low value; - when the last counted number of electrical pulses or the first increasing function of this last number is higher than a second determined threshold, or when a sequence of counted numbers of electrical pulses including this last number or a sequence of first increasing functions of each of these numbers meets a second selection criterion, according to which at least one of the numbers of the sequence or the first increasing function of this number is higher than a second determined threshold, the value of the second supply voltage is increased if this value is less than a given high value.

2. The control device according to claim 1, characterized by The logic circuit (20) is arranged so as to enable it to determine in which value range, among a plurality of determined value ranges, the counted number of electrical pulses or the first increasing function of this number or the second function of a sequence of counted numbers of electrical pulses or the second function of a sequence of first increasing functions of each of these numbers is located, and so as to enable it to periodically select a voltage value from among said plurality of different values provided for the second supply voltage as a function of the last determined value range.

3. The control device of claim 2, wherein The plurality of value ranges comprises a first value range having as an upper limit said first determined threshold, a second value range having as a lower limit said second determined threshold, and a third value range located between the first and second value ranges and having as upper and lower limits respectively the first determined threshold and the second determined threshold; and in that the logic circuit (20) is arranged so that, for each new selection: - when the last counted number of electrical pulses or the first increasing function of this last number or the second function of a sequence of counted numbers of electrical pulses including this last number or the second function of a sequence of first increasing functions of each of these numbers is in the first value range, the value of the second supply voltage is decreased if this value is greater than said low value; - when the last determined ratio of electric pulses or a second function of a sequence of determined ratios of electric pulses including the last ratio or a second function of a sequence of first increasing functions of each of these ratios is within the lower range of values, the value of the second supply voltage is decreased if it is greater than said low value; - when the last determined ratio of electric pulses or a second function of a sequence of determined ratios of electric pulses including the last ratio or a second function of a sequence of first increasing functions of each of these ratios is within the lower range of values, the value of the second supply voltage is decreased if it is greater than said low value.

4. The control device of claim 2, wherein The control device (2) comprises a measuring circuit (18) arranged so as to enable it to detect and count the alternations or cycles of the induced voltage in the supply coil (B2) or in the at least one supply coil while the rotor is rotating, each successive time period being defined by a given number of successive alternations or cycles detected in the induced voltage; and in that the logic circuit (20) is arranged so as to enable it to determine, for each successive time period, the ratio of electric pulses per alternation or cycle of the induced voltage, this ratio being equal to the counted number of electric pulses in the time period under consideration divided by the given number of alternations or cycles in this time period, this ratio defining a first increasing function of the counted number of electric pulses.

5. The control device of claim 4, wherein The measuring device is formed by: - a comparator (18a) having two inputs connected respectively to the first and second terminals (27, 28) of the supply coil (B2) and providing, when the rotor (6) is rotating, a digital signal (Pol_B2) indicative of the instantaneous polarity of the induced voltage in this coil, - at least one first switch (SM1, SM2) allowing the first terminal (27) of the supply coil (B2) to be temporarily connected to a reference voltage lower than the first supply voltage, and - a counter (18b) arranged to count all the transitions between its two states in the digital signal, corresponding respectively to the two polarities of the induced voltage, and thus to count the number of alternations of this induced voltage; or to count all the transitions to a given state of the digital signal, and thus to count the number of cycles of the induced voltage.

6. The control device according to claim 4 or 5, characterized by The plurality of ranges of values comprises a lower range of said ratio having as upper limit said first determined threshold, a higher range of said ratio having as lower limit said second determined threshold, and an intermediate range of said ratio having as lower and upper limits respectively the first and second determined thresholds; and in that the logic circuit is arranged so that, at each new selection of the voltage value of the second supply voltage: - when the last determined ratio of electric pulses or a second function of a sequence of determined ratios of electric pulses including the last ratio or a second function of a sequence of first increasing functions of each of these ratios is within the lower range of values, the value of the second supply voltage is decreased if it is greater than said low value; - when the last determined ratio of electric pulses or a second function of a sequence of determined ratios of electric pulses including the last ratio or a second function of a sequence of first increasing functions of each of these ratios is within the lower range of values, the value of the second supply voltage is decreased if it is greater than said low value. - when the last determined electric pulse ratio or a second function of the sequence of determined electric pulse ratios including the last ratio is in the intermediate range, maintaining the value of the second supply voltage at the value resulting from the previous selection; - when the last determined electric pulse ratio or a second function of the sequence of determined electric pulse ratios including the last ratio is in the higher range, increasing the value of the second supply voltage if the value of the second supply voltage is less than said high value.

7. The control device of claim 6, wherein said first determined threshold is equal to 50%, said intermediate ratio range is between 50% and 75%, and said second determined threshold is equal to 75%.

8. The control device of claim 1, wherein The voltage divider comprises a switching circuit (22) arranged between, on the one hand, the stator and, on the other hand, the supply unit supplying the first supply voltage and the ground of the control device, the voltage divider being arranged so as to enable it to selectively divide the first supply voltage by a number of integers greater than 1.

9. The control device of claim 8, wherein The voltage divider comprises N capacitors C n , n = 1 to N, wherein N is an integer greater than 1; And in that the logic circuit is then arranged so as to enable it to open and close the switches of said switching circuit (22) in order to generate a succession of said electric pulses, each succession comprising S+1 successive electric pulses, where S is an integer chosen between 1 and N, each succession being generated as follows: - first, during said pulse duration, the supply unit is connected to a first capacitor C1 of the N capacitors via the stator, supplying it with the first supply voltage, in order to generate the first electric pulse in the considered pulse succession; - then, when the number S is equal to 2, during this pulse duration, the stator is connected between the capacitor C2 and the capacitor C1, in order to generate the second electric pulse; Or, when the number S is greater than 2, each time during the duration of the pulse, the stator is connected in succession between capacitors C included among the S capacitors of the N capacitors J and the capacitors C J-1 where J varies from 2 to S, so as to generate in succession S-1 electric pulses; - finally, during the duration of the pulse, the stator is connected between the capacitor C S and the ground, so as to generate the last electric pulse of the series of electric pulses under consideration; And in that at each new selection of said voltage value, the logic circuit (20) can reselect the number S; said plurality of different values provided for the second supply voltage corresponding respectively to a plurality of voltages defined by the division of the first supply voltage by m, where m = 2 to N+1.

10. The control device of claim 9, wherein The N capacitors Cn have substantially the same capacitance, n = 1 to N.

11. The control device according to claim 9 or 10, characterized in that The number N is intended to be between 3 and 6, inclusive.

12. The control device according to claim 9 or 10, characterized by In said given operating mode or state of the electric machine, the first supply voltage divided by N+1 is greater than the absolute value of the maximum induced voltage generally generated across the stator.

13. The control device of claim 12, wherein, The control device is arranged so that each electric pulse is generated when the induced voltage across the stator is substantially equal to the maximum induced voltage.

14. The control device of claim 1, wherein The electric pulses have a constant pulse duration at least over each time interval lasting a few tens of revolutions of the rotor.

15. The control device of claim 1, wherein The electric machine (4) is a direct current electric machine.

16. The control device of claim 1, wherein The control device is arranged to control the average rotation speed of the rotor (6) so as to be equal to a setpoint speed.

17. A timepiece comprising a continuous rotation electric machine (4) and control means (2) for controlling the supply of power to the electric machine, characterized in that, said control device being the control device of any one of claims 1 to 16.

Images