Method for supplying power to a stepping motor and drive device for operating a stepping motor

Abstract

A method for supplying power to a stepping motor (10) having a stator (12) equipped with at least a first winding (121) and at least a second winding (122) that are sequentially supplied according to the power supply frequency is disclosed, comprising the steps of sequentially and periodically energizing the first winding (121) and the second winding (122): operating at an operating voltage Va' for a first energizing time ta1; and operating at a maintenance voltage Vm lower than the operating voltage Va' for a second energizing time ta2. During a first energizing time ta1, the energized winding exerts a driving torque on the rotor (11), first aligning the rotor (11) with the power supply winding, and then maintaining the rotor (11) in the aligned position during a second energizing time ta2; the first energizing time ta1 is approximately equal to the operating time t2-t1, which is the time from the first moment t1 when the operating voltage Va' is applied to the power supply winding to the moment t2 when the rotor (11) rotates in accordance with the power supply winding.

Description

Technical Field

[0001] The present invention relates to a method for supplying power to a stepping motor and a driving device for operating a stepping motor, and more particularly to a driving device for activating an electronic expansion valve of a refrigeration cycle machine.

Background Art

[0002] Currently, in the field of realizing precise actuators that can be activated electrically or electronically, the use of stepping motors is common, particularly for activating electronic expansion valves for refrigeration cycle machines. In technical terms, a stepping motor, which is better known as a synchronous motor equipped with permanent magnets.

[0003] This type of motor applies torque to the opposing rotor to obtain a predetermined rotational step of the rotor, whereby the rotational displacement of the rotor, and thus the rotational displacement of the mechanical unit designed to move the rotor, is directly related to the number of rotational steps to be executed.

[0004] Stepping motors are driven by controllers, which are well-known in this field by the term "driver", and which can traditionally be of two types: unipolar or bipolar.

[0005] <​​​​​​​​In the original (Italian) text, the terms "passo" and "step" are used in a completely semantically redundant and interchangeable manner, as are the terms "stepper" and "passo-passo" which refer to the electric motor in question, and this is also true for the terms "driver" and "controllore" unless the meaning of the related terms is specifically stated otherwise.

[0008] In the case of a unipolar driver, power consumption is determined by the impedance of the controlled motor winding, whereas in the case of a bipolar driver, power consumption is related to the current set by the driver itself.

[0009] In either case, the power used is the power required to move the motor, that is, the power that provides the rotor with effective rotation for the specific intended application.

[0010] Structurally, bipolar drivers consist of more complex and expensive circuit solutions than unipolar drivers, but they guarantee the possibility of independence from the impedance of the power cable, and therefore allow for longer cable lengths.

[0011] In addition, drivers performing microstepping operation are less susceptible to step losses that may occur as a result of resonance generated by systems controlled in other operating modes.

[0012] Therefore, a stepping motor is generally a digital motor, and its movement is achieved by angular steps of the rotor's rotation.

[0013] The system is stable only at the step position, and in order to maintain this stability, the motor must be continuously powered, even between consecutive steps.

[0014] Therefore, in general, in conventional methods, stepping motors are powered by the associated driver according to two levels of power supply, except in the case of microstepping control. That is, the first level is designed to actuate the rotation of the rotor by only one step, and the second level is designed to ensure that the alignment of the rotor between steps is maintained.

[0015] Therefore, the motor, together with the opposing driver, absorbs step power when the driver supplies power to the motor at a first level, i.e., facilitates the execution of the rotor steps, and absorbs holding power when the driver supplies power to the motor at a second level, i.e., maintains the rotor in the position reached after the steps.

[0016] As is well known, the holding power is a percentage of the step power, and this generally varies indicatively between 10% and 30% in its nominal value.

[0017] In particular, in the case of electronic valve control in refrigeration cycle machinery, this is essential to ensure that the valve position is reliably maintained in accordance with changes in relative opening degrees, corresponding to steps performed by the motor. [Prior art documents] [Patent Documents]

[0018] [Patent Document 1] Japanese Patent Publication No. 2006-101618 [Patent Document 2] UK Patent Application Publication No. 1434947 [Patent Document 3] U.S. Patent No. 4520302 [Overview of the Initiative] [Problems that the invention aims to solve]

[0019] Therefore, the problem underlying the present invention is to optimize the operation of a conventional stepping motor by increasing the torque provided by the motor with the same power absorbed, or by reducing the power absorbed with the same torque provided by the motor, particularly in the operation of the electronic valve of a refrigeration circuit machine.

[0020] Therefore, the object of the method for supplying power to a stepping motor and the drive device for operating a stepping motor according to the present invention is to solve this problem.

[0021] As part of this problem, one object of the present invention is to propose a method for supplying power to a stepping motor and a drive device for operating a stepping motor, which enables the power supply to the motor windings to be limited to what is necessary to facilitate relative steps and enables the consumption of the motor to be reduced while providing the same torque.

[0022] Among this problem, the object of the present invention is to produce a method for supplying power to a stepping motor and a drive device for operating a stepping motor, which enables the energization time of the motor windings to be limited to the time necessary to facilitate relative steps, enables the torque provided by the motor to be increased with the same power consumption of the motor compared to the above-mentioned conventional solutions, and increases the efficiency of the operation of the electronic valve of the refrigeration circuit machine using this motor.

[0023] Another object of the present invention is to propose a method for supplying power to a stepping motor and a drive device for operating the same, which can miniaturize the stepping motor and the drive device for operating the same in order to reduce the overall dimensions of the electronic valve of the refrigeration circuit machine.

[0024] [[ID=ID=19]] Another object of the present invention is to provide a method for supplying power to a stepping motor and a drive device and operating the drive device, which can reduce the heat dissipation of the drive device while maintaining the operating efficiency of the stepping motor.

Means for Solving the Problem

[0025] This object is achieved by a method for supplying power to a stepping motor and a drive device for operating the stepping motor, in accordance with the appended independent claims.

[0026] Detailed features of the method for supplying power to a stepping motor and the drive device for operating the stepping motor according to the present invention are described in the dependent claims.

[0027] Further features and advantages of the present invention will become more fully apparent from the following description of preferred but non-exclusive embodiments of a method for supplying power to a stepping motor and a drive device for operating the stepping motor according to the present invention, which are shown by way of non-limiting examples in the accompanying drawings listed below.

Brief Description of the Drawings

[0028] [Figure 1] It is a diagram showing a schematic cross-sectional view of a unipolar electric stepping motor. [Figure 2] It is a diagram showing the conventional operation phases of the electric stepping motor schematically shown in FIG. 1. [Figure 3] It is a diagram schematically showing an example of supplying power to an electric stepping motor according to the method of supplying power according to the present invention. [Figure 4] It is a diagram schematically showing an example of supplying power to an electric stepping motor according to the method of supplying power according to the present invention. [Figure 5] It is a diagram schematically showing an example of supplying power to an electric stepping motor according to the method of supplying power according to the present invention. [Figure 6] It is a diagram showing the tendency of the current with respect to the nominal value, which occurs during the operation of the motor referred to in the present invention. [Figure 7a]Two simplified diagrams of a unipolar motor and a bipolar motor, respectively, that can employ the method according to the present invention are shown, where the electronic symbols are intended to represent components that are themselves traditionally known by their respective relative symbols. [Figure 7b] The present invention presents two simplified diagrams of a unipolar motor and a bipolar motor, respectively, which can employ the method according to the present invention, where the electronic symbols are intended to represent components that are themselves traditionally known by their respective relative symbols. [Modes for carrying out the invention]

[0029] Referring particularly to the drawings described above, a method for supplying power according to the present invention is disclosed, which can be used to operate a stepping motor 10, i.e., a conventional permanent magnet synchronous motor which may be a unipolar or bipolar motor for operating an electronic valve of a refrigeration cycle machine.

[0030] Such a method of supplying power can be implemented by a drive unit for an electronic valve in a refrigeration cycle machine, which is connected to and operates the stepping motor 10.

[0031] In general, and in ways known by itself, the drive unit can be programmed or configured to actuate the electric motor according to alternative operating modes known by itself and identified in technical terms as "half-step" or "full-step," but this will not be explained further.

[0032] The present invention is applicable to solutions operating in microstepping mode, but it should be noted that in this case, if there are many voltage microsteps, sampling of the back electromotive force at a frequency comparable to the microstepping frequency is required, and since the magnitude of the step voltage V is small and the magnitude of the back electromotive force is similarly small, accurate detection becomes more difficult. However, as described above, the present invention can be applied to microstepping devices by solving the underlying simple electrical logic problem.

[0033] The stepping motor 10 may include a magnetic rotor 11 having a rotating shaft and a stator 12 that houses it.

[0034] The stator 12 has at least a first winding 121 and at least a second winding 122 arranged sequentially in the circumferential direction of the rotation axis, and power is supplied sequentially according to the power supply frequency to generate driving torque to the rotor 11.

[0035] Conventional methods for supplying power to a stepping motor include supplying power to a winding, which will be referred to below as the "powered winding." - During the first power supply time ta1, it operates at the actuation voltage Va; - During the second energizing time, it operates at a maintenance voltage Vm lower than the operating voltage Va.

[0036] The power supply winding is configured such that the first winding 121 or the second winding 122 are energized sequentially and periodically, and following the energization at the operating voltage Va of the power supply winding, the stator 12 applies a driving torque to the rotor 11, aligning the rotor 11 according to the power supply winding for a first energizing time ta1, and then maintaining the rotor 11 in the aligned state for a second energizing time ta2.

[0037] Figure 2 illustrates the energizing sequence of the motor schematically shown in Figure 1, which itself is represented in a traditional way, with the sequential energizing of the first winding 121 and the second winding 122 referring to the four phases from phase A to phase D.

[0038] Figure 2 shows the first energizing time ta1 and the second energizing time ta2 for phase A only, and it is clear that this is applicable to the further phases B, C, and D.

[0039] This figure also schematically shows the trend profile of the winding current Ia flowing through the first and second windings 121 and 122 following the application of the operating voltage Va and the maintenance voltage Vm.

[0040] The operating voltage Va and the maintenance voltage Vm are periodically applied to the first and second windings 121 and 122, respectively, and as a result, it can be seen how fluctuations in the winding current Ia flowing through the first and second windings 121 and 122 occur in the conventional manner.

[0041] The example in Figure 2 shows the conventional operation of the first and second windings 121 and 122, which are periodically energized with an operating voltage Va and a maintenance voltage Vm for energizing times ta1 and ta2 fixed in the conventional method.

[0042] Figure 2 illustrates how this conventional operation generates corresponding changes in the winding current Ia (for the sake of clarity in the figure, its reference is shown only in relation to phase A) and generates the operating sequences of phases A, B, C, and D along with the corresponding rotations of the rotor 11 in the stator 12, as shown at the top of Figure 2.

[0043] Unlike such conventional solutions, the present invention sets the first energizing time ta1 to be approximately equal to the operating time t2-t1, which is the time from the first moment t1 when the operating voltage Va is applied to the power supply winding to the moment t2 when the rotor 11 rotates in accordance with the power supply winding, in order to significantly improve driving efficiency.

[0044] For example, the moment of rotation t2 can be considered the moment when the rotor reaches the next step or instant.

[0045] Therefore, as can be immediately understood from Figure 3, it is clear that the power supply method according to the present invention can increase the power supply efficiency of a stepping motor and reduce power absorption at the same torque compared to conventional solutions. In Figure 3, the trends of the voltage V applied to the power supply winding and the current I induced in the power supply winding are shown by solid lines when they result from the implementation of the power supply method according to the present invention and by dashed lines when they result from conventional starting.

[0046] For the sake of explanation, in the following drawings and accompanying drawings, quantities obtained from the use of the method for supplying power according to the present invention are identified by adding an apostrophe with respect to the corresponding quantities obtained from the application of conventional actuators.

[0047] Therefore, ta1' represents the first energizing time at the operating voltage Va' of the power supply winding according to the power supply method according to the present invention, and ta1 and Va each represent the first energizing time at the operating voltage of a conventional actuator.

[0048] Examples from Figures 3, 4, and 5 illustrate how the supply method according to the present invention can reduce the absorbed power with the same torque transmitted by the motor 10, as seen in Figure 4, or how to obtain a greater torque transmitted by the motor 10 with the same absorbed power compared to conventional solutions, as seen in Figures 5 and 6.

[0049] This makes it possible to obtain a motor-driven mechanical valve for a refrigeration cycle that, while ensuring at least the same level of opening and closing accuracy and reliability as conventional valves, results in lower power consumption and, as seen below, potentially more compact designs.

[0050] Therefore, referring particularly to the examples in Figures 3 and 4, the first energizing time ta1 at the operating voltage Va is significantly reduced to the operating time ta1' = t2 - t1, where the moment of rotation t2 corresponds to the moment when the rotor performs a rotation step.

[0051] The moment of rotation t2 can be determined by a detection step that detects a back electromotive force consisting of the inverse peak of the electromotive force, i.e., an electromotive force opposite to the electromotive force that attempts to generate the operating voltage Va.

[0052] The detection step can be performed, for example, by measuring the current in a shunt resistor or by using the Hall effect, and is designed to detect the back electromotive force resulting from the orientation of the rotor 11 according to the power supply winding.

[0053] In other words, the detection step is designed to directly or indirectly detect the fluctuations in the magnetic field caused by the alignment of the rotor and the power supply winding.

[0054] This achieves the significant advantage of making the motor detection or step corresponding to the generation of back electromotive force substantially independent of the specific thermal and mechanical conditions of the motor and its operation.

[0055] This detection step can detect back electromotive force by monitoring the current flowing through the first and / or second windings 121 and 122 and detecting fluctuations in the current, as shown in the example in Figure 6.

[0056] In particular, the detection step may include monitoring the current flowing through either the first winding 121 or the second winding 122, which is not the power supply winding.

[0057] In particular, this method makes it possible to detect the current fluctuation in a shunt resistor arranged in series with the first winding 121 or the second winding 122.

[0058] This solution, by adding a shunt resistor to the unipolar motor, allows for a particularly simple circuit structure and is advantageous in terms of relative cost, thus reducing the cost of the device.

[0059] On the other hand, in the case of a bipolar motor, the shunt resistor is already provided in the motor itself, so it has the advantage of a simple structure and does not require any modification of the motor itself.

[0060] Furthermore, by detecting the current difference or current fluctuation across the shunt resistor Rs, problems related to current polarity can be avoided.

[0061] In particular, this method may include a discrimination step for analyzing the current trends flowing through the first and / or second windings 121 and 122.

[0062] This discrimination step may include detecting the difference in current flowing through the first winding 121 and / or the second winding 122, or the trend deviation. That difference is, namely: - When there is no significant movement of the rotor 11, for example when it is aligned according to the power supply winding 121 or 122, the nominal current In corresponds to the current flowing through the first winding 121 and / or the second winding 122, preferably the shunt resistor Rs; - For example, as shown in Figure 6, when a back electromotive force is generated by the alignment of the rotor 11 according to the power supply winding, a correction current Im corresponding to the current flowing through the first winding 121 and / or the second winding 122, preferably the shunt resistor Rs, It is the difference between them.

[0063] Fluctuation I b-EMF This can be given by the deviation of the corrected current Im from the nominal current In, which is evaluated by a discrimination algorithm of a discrimination device D that can be integrated with the control device C and can detect the deviation of the current flowing through the shunt resistor Rs.

[0064] This determination step may include, following the detection of the modified current, reducing the supply voltage of the power supply winding from the operating voltage Va' to the maintenance voltage Vm.

[0065] Furthermore, if necessary, a delay time ts may be provided after the operating time t2-t1 until the supply voltage of the power supply winding decreases from the operating voltage Va' to the maintenance voltage Vm.

[0066] Preferably, the determination step is performed by detecting the current flowing through a resistor Rs, such as a shunt resistor, connected in series with both the first winding 121 and the second winding 122, so as to detect the current regardless of whether the first winding 121 or the second winding 122 is the power supply winding.

[0067] In particular, by including a discrimination step, the method of the present invention becomes insensitive to boundary conditions such as temperature changes or boundary conditions arising from the mechanical effects of the valve.

[0068] Thus, the discrimination step performed according to the method of the present invention makes it possible to detect the difference between an unhindered flow state of the current flowing through the shunt resistor and a flow state affected by the back electromotive force resulting from the rotation of the rotor, without being affected by the specific characteristics of the motor to which it is applied.

[0069] For example, a solution that provides a voltage threshold definition for detecting the generation of back electromotive force caused by aligning the rotor 11 according to the power supply winding is, unlike the solution of this method, sensitive to temperature effects that determine the variation in the threshold.

[0070] Furthermore, by using a shunt resistor Rs in series with the first winding 121 and the second winding 122, the direction of current flow can be made unique, thereby avoiding the technical compromises required to operate by detection based on the average voltage threshold level.

[0071] In particular, according to this method, this detection step can be performed substantially continuously while the operating voltage Va' is supplied.

[0072] Here, the term continuous detection can be understood as detection performed, for example, by sampling at high frequencies while an operating voltage Va' is supplied.

[0073] Such monitoring is preferably performed on the windings between the first winding 121 and the second winding 122 that are not power supply windings.

[0074] Such monitoring is done in a well-known way to detect current fluctuations I resulting from back electromotive force. b-EMF It can be used to detect [something].

[0075] After the detection step, a reduction step may be provided in which the power absorbed by at least one power supply winding is reduced relative to the maximum power absorbed by at least one power supply winding during the operating time t2-t1.

[0076] This reduction step can be carried out by one or more of the following actions: - Reduce the voltage V' applied to at least one of the power supply windings from a value equal to the operating voltage Va' to a value equal to the maintenance voltage Vm; - For example, increasing the electrical resistance of the power supply winding by inserting a resistor in series with the power supply winding, such as inserting a shunt resistor (Rs) in series with the power supply winding; - PWM modulation reduces the effective voltage of the power supply winding.

[0077] In known methods, the stepping motor 10 has a configuration that determines a threshold Is of the current flowing through the power supply winding, and when this threshold Is is reached or exceeds the threshold, a magnetic flux is generated by the power supply winding, thereby giving the rotor 11 enough torque to determine alignment according to the power supply winding.

[0078] Here, "alignment" refers to the alignment of the coil's axes.

[0079] The operating voltage Va' in the power supply method according to the present invention, together with the first operating time ta1', may be selected such that the pair of values ​​of the operating voltage Va' and operating time ta1' minimizes the power absorption of the stepping motor 10 during the execution of the power supply method, or it may be selected so as to maximize the torque exerted on the rotor 11 by the power supply winding.

[0080] Clearly, ta1' is related to the selection of Va' to determine the current in the motor windings suitable for manufacturing a stepping motor. That is, the selection of Va' and ta1' is such that, in either case, at time ta1', the application of Va' is sufficient, depending on the motor's accidental characteristics, to generate a torque in the windings that induces the motor to step.

[0081] In other words, within the limitations on the selection of Va' given by the motor's accidental tolerability characteristics in a particular application, ta1' is minimized to reach a current suitable for generating motor steps.

[0082] In other words, once the operating voltage Va' is selected for a particular application, the energizing time ta1' can be selected in such a way that it minimizes the power absorption of the stepping motor 10 during the execution of the power supply method, or it can be selected to maximize the torque exerted on the rotor 11 by the power supply winding.

[0083] As mentioned above, these two options are illustrated as examples in Figures 3, 4, and 5, respectively.

[0084] In the first case, for example, as shown in FIG. 3, at the same operating voltage Va’ = Va, compared to the conventional solution, the power is significantly reduced by reducing the first operating time, which is reduced from the conventional value ta1 to a lower value ta1’ according to the method of supplying power according to the present invention.

[0085] In the second case, for example, as shown in FIG. 4 or FIG. 5, when the same power is absorbed by the motor 10, the operating voltage increases to Va’ > Va, and the operating time correspondingly decreases to ta1’ < ta1, so that the drive torque significantly increases.

[0086] Particularly, for applications that provide an available power supply corresponding to 24VAC, which is typical of general industrial automation systems, the method of supplying power according to the present invention is particularly advantageous because it enables heat dissipation reduction by using an unregulated or adjusted rectified current without, for example, requiring a power supply device or regulator. For example, in some conventional applications, it is possible to avoid using capacitors used to create a voltage buffer.

[0087] In other words, according to the present invention, when a 24V AC power supply is available at 50Hz together with a motor designed to execute steps every 10ms, it is possible to use it directly at the peak voltage to obtain the supply voltage of the motor without using a regulator.

[0088] Therefore, the present invention enables the use of a 24VAC 50Hz voltage that is normally available in industrial networks without requiring a voltage regulator, avoids relative electrical dissipation, and can reduce the overall size of the drive device.

[0089] Such capacitors may have a capacitance of, for example, about 1000 μF, but are bulky in practice. By eliminating the capacitor, as is permissible with the adoption of the power supply method according to the present invention, it is possible to miniaturize the drive unit operating according to such a power supply method and integrate it directly into the body of the electric motor. Furthermore, it has the advantage of reducing the physical distance between the control device C and the windings, and making it easy to utilize the configuration of the unipolar stepping motor 10, which is known to be structurally simple and inexpensive.

[0090] Therefore, the sum of the first energizing time ta1 and the second energizing time ta2 can be selected to have a power supply frequency that is approximately equal to the frequency of the power supply network to which the stepping motor 10 is connected and supplied.

[0091] This sum can be made approximately equal to the period of the power supply frequency, such as 10ms or 16.67ms for frequencies of 50Hz or 60Hz, respectively.

[0092] Generally, this sum can be made roughly equal to the period of the accidental power supply frequency, thereby minimizing or eliminating the need for the power supply, particularly the conventional rectifier capacitor, such as a 1000μF capacitor, and thus enabling miniaturization, i.e., a reduction in the overall dimensions mentioned above.

[0093] In fact, it is possible to synchronize the steps of the stepping motor 10 with the main power supply frequency, and as a result, the power absorption for generating the steps is synchronized with the peak voltage peak via the diode of the drive unit that supplies power to the motor, making it possible to reduce the capacitance of the rectifier capacitor, or ideally, to not provide a rectifier capacitor at all, and in either case, it becomes possible to significantly miniaturize the drive unit.

[0094] A drive device for the stepping motor 10 configured to realize the above-described method of supplying power is also an objective of the present invention.

[0095] The drive device can significantly reduce capacitance by, for example, limiting the overall size of capacitor elements with capacitances greater than 15 μF, thus mitigating structural influences.

[0096] This allows for an overall size that is suitable for integration with an electric motor, specifically a stepping motor 10.

[0097] The drive unit may be configured to be directly integrated with the stepping motor in order to minimize the distance between the drive unit itself and the first and second windings 121 and 122.

[0098] Preferably, the stepping motor 10 is a unipolar motor.

[0099] Therefore, it is understood how the method of supplying power to a stepping motor and the drive device for operating the stepping motor according to the present invention enable optimization of the operation of a conventional stepping motor by increasing the torque provided by the motor with the same absorbed power, or by reducing the absorbed power with the same torque provided by the motor, thereby enabling the achievement of set tasks and objectives.

[0100] In particular, the present invention provides a method for supplying power to a stepping motor and a drive device for operating it, which makes it possible to limit the power supply to the motor windings to the power supply strictly necessary to facilitate the motor's steps, and is advantageous in reducing the net power consumption of the motor while providing the same torque.

[0101] As disclosed herein, a method for supplying power to a stepping motor and a drive device for operating it also makes it possible to limit the energizing time of the motor windings to the time necessary to facilitate its steps, and to increase the torque provided by the motor for the same motor consumption compared to conventional solutions.

[0102] In addition, by reducing the voltage application time, for example, by passing the voltage from 24V to 30V, it is possible to reduce heat dissipation from the drive unit while maintaining the same operating efficiency. In fact, heat dissipation correlates with the square of the voltage, and torque correlates with the voltage because it is linked to the coil current.

[0103] Furthermore, the method for supplying power to the stepping motor and the drive device for operating it enable miniaturization of the drive device, especially when a conventional 24VAC power supply is available.

[0104] The present invention, conceived in this manner, is subject to numerous modifications and variations that fall within the scope of protection of the appended claims.

[0105] Furthermore, all details can be replaced with other technically equivalent elements.

[0106] Where reference numerals or numbers are used after the mentioned operational and technical features, these reference numerals or numbers are used solely for the purpose of enhancing the understanding of the description and the claims themselves, and therefore do not limit the interpretation of each element identified by the reference numeral or number, merely as an example.

Claims

1. A method for supplying power to a stepping motor (10), the motor comprising a magnetic rotor (11) having a rotating shaft (A), and a stator (12) housing the magnetic rotor, the stator (12) comprising at least a first winding (121) and at least a second winding (122) arranged sequentially along the circumferential direction of the rotating shaft (A), power being supplied sequentially according to the power supply frequency to generate a driving torque to the rotor (11), the method comprising the step of sequentially and periodically energizing the power supply windings, which are at least one of the first windings (121) and at least one of the second windings (122): - During the first energizing time ta1, it operates at the operating voltage Va'; - During the second energizing time ta2, it operates at a maintenance voltage Vm lower than the operating voltage Va'; As a result, following the energization of the power supply winding at the operating voltage Va', the stator (12) applies a driving torque to the rotor (11), initially orienting the rotor (11) according to the power supply winding during the first energization time ta1, and then maintaining the rotor (11) in that oriented state during the second energization time ta2. The first energizing time ta1 is set to be approximately equal to the operating time t2-t1, which is the time from the first moment t1 when the operating voltage Va' is applied to the power supply winding to the moment t2 when the rotor (11) rotates in conjunction with the power supply winding; Here, the moment of rotation t2 is determined by a detection step that detects a back electromotive force, that is, a back electromotive force consisting of an electromotive force opposite to the electromotive force that attempts to generate the operating voltage Va'; The detection step is designed to detect the back electromotive force arising from the alignment of the rotor (11) according to the power supply winding; and The detection step involves monitoring the current flowing through the first winding (121) and / or the second winding (122), and detecting fluctuations in the current to detect the back electromotive force. A method for supplying power to a stepping motor (10).

2. A method for supplying power to a stepping motor (10) according to claim 1, wherein the detection step provides monitoring of the current flowing through one of the windings, the first winding (121) or the second winding (122), which is not a power supply winding.

3. The detection step is followed by a reduction step designed to reduce the power absorbed by the at least one power supply winding to the maximum power absorbed by the at least one power supply winding during the operating time t2-t1, wherein the reduction step performs the following operations: - Reducing the voltage applied to at least one of the power supply windings from the operating voltage Va' to the maintenance voltage Vm; - For example, increasing the electrical resistance of the power supply winding by inserting a resistor in series with at least one of the power supply windings; - Reducing the effective voltage of at least one of the power supply windings by PWM modulation; A method for supplying power to a stepping motor (10) according to claim 1 or 2, selected by one or more of the following:

4. The stepping motor (10) has a configuration associated with a threshold value Is for the current flowing through the at least one power supply winding, wherein when the current flowing through the at least one power supply winding reaches and / or exceeds the threshold value Is, a magnetic flux is generated by the power supply winding, thereby causing the rotor (11) to receive sufficient torque to determine alignment according to the at least one power supply winding; The threshold value Is of the current corresponds to the voltage step value; A method for powering a stepping motor (10) according to any one of claims 1 to 3, wherein the operating voltage Va' is selected as a function of the step value to minimize the power absorption of the stepping motor (10) or to maximize the torque exerted on the rotor (11) by the power supply winding.

5. The sum of the first energizing time ta1 and the second energizing time ta2 is selected such that the stepping motor (10) has a frequency that is approximately equal to the frequency of the power supply network to which the motor is intended to be connected for power supply; Preferably, the sum is approximately equal to a period corresponding to the supply frequency, for example, 10 ms or 16.67 ms, and the frequency is approximately equal to a frequency equal to 50 Hz or 60 Hz, respectively, a method for supplying power to a stepping motor (10) according to any one of claims 1 to 4.

6. The process includes a determination step that provides detection of a difference or deviation in the trend of currents flowing through the first winding (121) and / or the second winding (122), wherein the difference is: - When there is no significant movement of the rotor (11), for example when it is aligned according to the power supply windings (121, 122), the nominal current In corresponding to the current flowing through the first winding (121) and / or the second winding (122) is, - When a back electromotive force is generated due to the alignment of the rotor (11) according to the power supply winding, a correction current Im corresponding to the current flowing through the first winding (121) and / or the second winding (122), A method for supplying power to a stepping motor (10) according to any one of claims 1 to 5, which is the difference between the two.

7. The method for supplying power to a stepping motor (10) according to claim 6, wherein the determination step detects the difference in current or trend deviation flowing through a shunt resistor Rs connected in series with the first winding (121) and the second winding (122).

8. The aforementioned discrimination step can be integrated with the control device C and is based on the difference or trend deviation given by the deviation of the corrected current Im from the nominal current In, as evaluated by a discrimination algorithm of the discrimination device D, which can detect the deviation of the current flowing through the shunt resistor Rs. ｂ－ＥＭＦ A method for supplying power to a stepping motor (10) according to claim 6 or 7, which provides the ability to detect a stepping motor (10).

9. A drive device for a stepping motor (10), configured to carry out the method of supplying power according to any one of claims 1 to 8.

10. The method for supplying the power is the method according to claim 5, wherein the drive unit comprises a capacitor member having a limited capacity, i.e., a capacity not exceeding 15 μF, generally having an overall size suitable for integration with an electric motor, the drive unit is directly integrated with the electric motor and configured to minimize the distance between the drive unit and at least the first winding (121) and the second winding (122), and preferably the stepping motor (10) is a unipolar motor, the drive unit for a stepping motor (10) according to claim 9.

11. The first winding (121) and the second winding (122) are connected in series with a shunt resistor Rs, the shunt resistor Rs having a difference or trend deviation given by the deviation of the correction current Im from the nominal current In. ｂ－ＥＭＦ A discrimination device D is connected, which is designed to implement a discrimination algorithm configured to detect the following: Here - The nominal current In corresponds to the current flowing through the first winding (121) and / or the second winding (122) when there is no significant movement of the rotor (11), i.e., when it is aligned according to the power supply windings (121, 122). - The correction current Im corresponds to the current flowing through the first winding (121) and / or the second winding (122) when a back electromotive force is generated as the rotor (11) aligns according to the power supply winding. A drive device for a stepping motor (10) according to claim 9 or 10.

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