Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P8/00—Arrangements for controlling dynamo-electric motors rotating step by step
  • H02P8/005—Arrangements for controlling dynamo-electric motors rotating step by step of linear motors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P8/00—Arrangements for controlling dynamo-electric motors rotating step by step
  • H02P8/14—Arrangements for controlling speed or speed and torque
  • H02P8/16—Reducing energy dissipated or supplied

Definitions

• the present invention relates to the field of polyphase brushless actuators, controlled in step-by-step mode by a microcontroller. It concerns both rotary actuators and linear actuators.
• the present invention relates to the field of refrigerant control actuators or not.
• Such actuators generally comprise a rotor provided with permanent magnets, moved by the magnetic field created by a set of coils controlled by a power electronics.
• the supply or not of each coil defines a relative position of the rotor relative to the stator.
• Stepped stepper motors have a limited number of discrete positions (usually as many positions as stator magnetic poles), but proportional-controlled stepper motors can increase accuracy. This is called “micro step” since the motor has several positions of balance between two steps.
• step will denote either a whole step or a "microstep”.
• the load angle is within a set acceptable range, the normal operation of the stepper motor along the programmed path is maintained without adjustment. However, a load angle that exceeds the range of this range indicates that a misstep has occurred, and the system controller initiates an action to recover lost engine steps to restore synchronism.
• US5029264 discloses an application of a stepper motor for moving a carriage
• detection means for detecting an angular position of the rotor of said stepping motor, the detecting means generating a pulse signal for each predetermined rotation angle of said rotor;
• control means for counting the pulse signals from said detection means, detecting a position of said carriage according to the signals pulses counted by said control means, outputting control signals to start and stop said carriage, and output an initialization signal;
• current switching means for counting the pulse signals from said detection means and changing an excitation current supplied to the coil of said stepper motor as a function of the pulse signals counted by said current change means for effecting a closed-loop control, current switching means also performing stepper motor drive of said stepping motor in response to the initialization signal of said control means, said current changing means bringing said rotor into a position stable and returning the counted value to a reference value, starting the change control of the excitation current in response to the start control signal from said control means and stopping the excitation current change control in response to the stop command from said control means.
• JP2007259568 discloses a stepper motor drive having a microstep function in which a sinusoidal current passes through a motor winding each time an external control pulse is applied and a basic pitch angle is segmented.
• the driving device comprises: an angle sensor for detecting the rotation angle of a rotor; an advance controller which calculates an excitation angle from an external control pulse and an angle of rotation of the rotor; an inverter for driving a stepper motor; a current controller for controlling the stepper motor current; a current detector for detecting a motor current; and a current control generator for generating current amplitude commands.
• the driving device is constituted such that an angle command is corrected using information on a change of angle sensor output obtained when two different current commands are generated by the current control generator when the motor is stopped.
• the US8810187B2 patent proposes to periodically check the advance of the rotor to verify that the pilot steps are respected but makes no continuous control of the load angle. Moreover, it does not dynamically modify the amplitude of the injected current in each step.
• the US5029264 patent is a BLDC steering stepper requiring a PID controller requiring numerous calculations and may generate setpoint overshoots.
• Patent JP2007259568 proposes to measure the position of the rotor in order to modify the phase of the pitch control but without modifying the amplitude of the current.
• the invention relates to a method of controlling a polyphase actuator consisting in supplying each phase with periodically varying voltage with a periodic sequence of pitch P ⁇ of constant duration and amplitude A n, ⁇ where n corresponds to the rank of the phase (for example, a three-phase motor has 3 ranks of phase) and i to the rank of the pitch (for example, a control at 48 steps per electrical period has 48 ranks) determining a target position PC ⁇ of the rotor of one actuator, to define a sinusoidal voltage envelope, said actuator further comprising a movable member, a stator equipped with electric coils and a sensor detecting the mechanical position of said movable member with respect to said stator, as well as a microcontroller characterized in that:
• Said microcontroller determines at times T sensor the mechanical position of said mechanical member
• Said microcontroller calculates, at each of said sensor moments T, the difference between said mechanical position and the target position PC ⁇ corresponding to the pitch P ⁇ and said microcontroller calculates a coefficient k as a function of said difference,
• Said microcontroller weights the supply amplitude applied to said phases by said coefficient k to supply said phases with weighted amplitudes voltages A n, ⁇ * k (A n, ⁇ multiplied by k).
• each phase of the motor is supplied with voltage according to pulse length modulation (PWM).
• PWM pulse length modulation
• the coefficient k referred to is a coefficient that modifies the duty cycle and therefore the average level of voltage applied to each phase.
• the method comprises at least one sensor acquisition time T for the mechanical position of said mechanical member for a pitch P ⁇ , more preferably at least 4 moments of acquisition T sensor ⁇
• Said coefficient k may be proportional to the difference between said mechanical position and the PC ⁇ target position corresponding to the pitch P ⁇ , but any other mathematical function may be used.
• the invention will preferably be used for movable member which is the rotor of the actuator to avoid being hampered by the errors induced by the mechanical clearances, but said movable member can also be moved by the rotor via a motion transformation member .
• said rotor is movable over a plurality of turns.
• the movement is helical and the rank of the turn, relative to an initial position, is determined by the standard of the signal delivered by the two-dimensional magnetic sensor. In this case, the rank of the round is compared to a previously recorded value.
• the method comprises a calibration step of controlling the displacement of the movable member to a mechanical stop, and detecting the blockage by reaching said coefficient k to a threshold value k Seuii and storing in a memory the pitch P ⁇ corresponding to the reaching of this threshold value as reference P 0 of said movable member.
• the method comprises a step of holding the movable member in a stop position, consisting of periodically measuring the coefficient k, and controlling the amplitude of the supply voltage. said phases if said coefficient k exceeds a threshold value.
• the electrical control of the phases is modified to approach the measured position of the rotor with the desired mechanical position.
• the invention described will be particularly advantageous for controlling a fluid control valve.
• FIG. 1 represents an isometric view of a control valve, given by way of example, and able to use the present control method
• FIG. 2 represents a cross-sectional view of the control valve shown in FIG. 1
• FIG. 3 is a longitudinal sectional view of the control valve shown in FIG. 1 with an enlarged isolated view
• FIGS. 4a, 4b and 4c show examples of sensor magnet magnetization variants used on electric motor rotors driven by the present control method
• FIG. 5 represents a partial longitudinal sectional view of a control valve, according to another example, and which can use the present control method
• FIG. 6 represents an isolated view of a stator belonging to a motor that can use the present control method
• FIG. 7 represents a schematic view of the load angle of a driven motor that can use the present control method
• FIG. 8 represents a typical operating algorithm of the present control method
• FIG. 9 represents a magnetic induction graph detected by a magnetosensitive probe associated with one of the sensor magnets of FIGS. 4a to 4c,
• FIG. 10 represents the method implemented over several rotor turns of an actuator according to the invention
• FIG. 11 represents the operation of the method of the present invention illustrated through a graph
• FIG. 12 represents an enlargement of FIG.
• FIG. 13 represents the stop detection method illustrated through a graph
• FIG. 14 represents the different voltage values applied to each phase of an engine
• FIG. 15 represents the dynamic modification of the value k as a function of the load applied to the rotor.
• FIG. 1 represents an isometric view of a first embodiment of a valve according to the invention, associating an electrical actuation assembly and a mechanical assembly creating a circulation path for a heat transfer fluid.
• the valve is thus more particularly composed of an electric actuator (1) which sets in translation, along the axis (3) of displacement, a needle (not visible here) with the aid of an electric motor.
• the actuator (1) is fixed on the valve body (2) which comprises the passage channels (20) of a heat transfer fluid whose flow rate is controlled by said needle.
• the electric actuator (1) comprises a cover (19) on the upper part, and is fixed to the valve body (2) by axial fixing means (4), such as screws or bolts.
• FIG. 2 is a view from above of the first embodiment without a cover and making it possible to appreciate the radial magnetic flux electric actuator which can be used in the present invention.
• Any other electrical actuator generating a torque at the level of the motion transformation can be used, for example magnetic flux along the axis of displacement.
• This actuator (1) has a stator (6) formed of a bundle of sheets forming teeth on which are placed, for some of them, electric coils (25), here 3 coils at 120 ° from each other .
• This stator (6) is housed in a housing (9) which may comprise a connector (5). In this view without lid
• Figure 3 shows a longitudinal section of a valve according to this first embodiment.
• valve body (2) has channels
• the fluid passage is managed by positioning the end of the needle (11) managed by the electric actuator (1), along the axis (3), in order to bring said needle end (11) closer or further away.
• the rotor (12) is composed of a nut portion (14) and which also forms, in this particular embodiment, the yoke and the support of the permanent magnets (13), the rotor setting in motion the needle
• the configuration presented here is particularly compact axially with a guidance entirely provided in the active height of the sheet bundle (10), this guidance being here realized by the screw (15) in cooperation with the nut (14) and by the body of the needle (11) with the inner surface of the fixed screw.
• a needle position sensor (11) is shown.
• This magnetic principle sensor is located on the upper part of the valve, above the rotor (12).
• a magnetic element (7) magnet is integral with the nut portion (14), therefore the rotor (12) and therefore the needle (11) ⁇
• This magnet (7) which has a magnetization is diametral perpendicular to the axis rotation of the rotor, either bipolar along the axis of the rotor (3), or a magnetization rotating about an axis perpendicular to the axis (3), is also immersed inside the bell (16).
• This magnetic element generates a magnetic field in the plane of the probe (19) perpendicular to the axis (3).
• this magnetic field will rotate synchronously with the rotor (12).
• this magnetic element (7) moves away or approaches the bottom of the bell (16).
• a magnetosensitive probe (8) detecting the angle of the field magnetic, and according to the uses the amplitude of the component of the magnetic field perpendicular to the axis (3) or the norm components perpendicular to the axis (3) emitted by the magnetic element (7).
• the distance or approximation of this magnetic element (7) relative to the magnetosensitive probe (8) thus makes it possible to modulate the field amplitude detected by the probe (8) and to give an image of the position of the needle (11). ).
• the probe (8) is carried by a printed circuit (18) located above the bell (16), under the cover (19).
• This printed circuit board (18) can also carry the connection points to the coils of the actuator (1) as well as the electronic components necessary for controlling the polyphase electric motor.
• the magnetic element (7) generating the axial magnetic field is made of magnet, based on neodymium iron boron, ferrite or cobalt samarium. This latter material has the advantage of a small variation in its magnetic properties as a function of temperature, thus minimizing the drifts of the sensor signal and minimizing the influence of the temperature gradients between the fluid and the magnetic field measuring probe. .
• This lower magnetic variation as a function of temperature is useful in the case of measuring the amplitude of the field to determine an axial position.
• the measurement of the angular position made by comparing the amplitudes of two non-collinear magnetic components perpendicular to the axis (3), is not dependent on the amplitude of these components.
• the probe (8) is a probe measuring at least two components orthogonal to the magnetic field, and possibly a three-dimensional probe.
• FIG. 4a shows a magnetic magnetic element (3) generating the field required for the measurement probe, magnetized diametrically, so with a vector located in the plane perpendicular to the axis of rotation of the rotor (3).
• FIG. 4b shows a magnetized magnetic element (7) generating the necessary field for the measurement probe, bipolar magnetized, where two parts of said magnetic element are magnetized according to two vectors in opposite directions and parallel to the axis of rotation of the rotor (3).
• FIG. 4c represents a magnetized magnetic element (7) generating the field required for the measurement probe, magnetized according to a rotating magnetization, the orientation of the magnetization inside said magnetic element rotating about an axis (22) perpendicular to the axis of rotation of the rotor (3)
• FIG. 5 represents an alternative to the construction of FIGS. 1, 2 and 3 in which the radial-flow electric motor is replaced by a claw motor
• FIG. 6 represents a solution of protection of the magnetic measurement probe with respect to the disturbing fields generated when an electric current flows through the stator windings (25).
• An additional stack of sheets (26) surrounds said coils to provide the streams generated by these coils a preferred magnetic path.
• Figures 7a, 7b, 7c and 7d show a schematic view of the stator vector (40) and the rotor vector (41).
• the vectors u, v, w are the orientations of the pairs created by each of the motor phases taken separately. This is a representation called "Fresnel diagram”.
• the stator vector (40) is the composition of the micropore electrical control signals at the terminals of the stator coils in the plane perpendicular to the axis (3).
• the rotor vector (41) is determined by the analysis of the signals transmitted by the probe (8) and translated in the Fresnel diagram from the position sensor position signal, knowledge of the number of pole pairs and a reference position.
• the loading angle corresponds to the angle between the stator vectors (40) and rotor (41) magnetic field.
• the resulting torque at the rotor generated by the power supply at the stator varies from a zero torque (50) when this angle is equal to 0 °, to a maximum when the vectors are at 90 °.
• the torque is directly proportional to the sine of the load angle and the supply current.
• the load angle is equal to 0 ° and the stator and rotor vectors are collinear.
• the actual angular position of the rotor is identical to the control position.
• the load angle (42) increases and is then no longer equal to 0 ° . This is illustrated in Figs. 7a, 7b, 7c and 7d where the generated torque at equal supply current is increasing.
• this load angle exceeds 90 °, the torque exerted decreases and may cause a loss of synchronism between the rotor and the stator field, called rotor stall.
• the process using this load angle to drive the motor is illustrated in Figure 8.
• This offset is determined periodically, at least one or more times per microstep. If the load angle (42) is constant, the computer keeps the constant coefficient value k. Yes the load angle (42) increases or decreases, the computer modifies the value of the coefficient k respectively higher or lower in order to modify the control voltage (via a different duty cycle) and therefore the amplitude of the current injected into the phases.
• the coefficient k is zero when the load angle is zero and it is maximum when the load angle is 90 °.
• the coefficient k can be a coefficient proportional to the load angle, but all other mathematical functions (quadratic or other) can be envisaged.
• FIG. 9 represents the different magnetic field components measured by the magnetic sensor, here the X (45) and Y (46) components according to two orthogonal vectors situated in a plane perpendicular to the axis of rotation (3) between a position ( 47) away from the probe and a position (48) close to the probe, positions separated by approximately 4 turns in this nonlimiting example.
• FIG. 10 illustrates the calculations made from the components of FIG. 9.
• the ratio of these two components (45) and (46) makes it possible to calculate the angle of the rotor magnetic field (41) by arctangent calculation of this ratio.
• the signal (41) has 4 periods which correspond to the 4 rotations made by the rotor.
• the calculation of the norm of the measured field (49) makes it possible to estimate the distance of said magnet (7) with respect to the measurement probe (8). This distance is either measured directly using this magnetic field module, or interpolated. In the latter case, thanks to the angular sensor position in a lathe is known precisely, and field amplitude variations are sufficient to determine in which turn the rotor (12) is located.
• Fig. 11 shows an example of electrical signals calculated by comparison of the control signal (40) and angular values (41) measured by the sensor. This graph shows the evolution as a function of time of the signals expressed in microstep (scale on the left) and in torque (scale on the right).
• a residual offset (51) between the desired position (40) and the actual position of the rotor (41) is equal to the load angle (42) but this is known and can be compensated by changing the control ( 40) of a value equal to the value of this residual offset (51) for the rotor to reach the desired position (55).
• FIG. 12 illustrates the phenomenon of discretization induced by the measurement of the sensor at the instant of the sensor, with at least 4 periods in a microstep (56).
• This graph presents in degree, the evolution of the signals (40, 41, 42) as a function of time.
• Figure 13 illustrates the use of the load angle (42) to detect a mechanical stop when moving the actuator.
• This graph shows in degree, the evolution of the signals and magnitude (40, 42, 52) as a function of time. It is then considered that the rotor has mechanically reached this stop when the load angle (42) exceeds a threshold value (52), for example 100 °, since the maximum permitted current is reached. Precise knowledge of the mechanical stop is therefore possible.
• Figure 14 illustrates the different voltage values applied to each phase of an engine according to the method of the present invention.
• the abscissa is the number of steps.
• the voltage value which is represented as the programmed register value in the microcontroller and which is used to keep constant the differences between the mechanical position and the target position.
• All steps Pi have a step duration and an amplitude An, i * k determined for each step.
• the amplitude value of each step is different in order to constitute a sinusoidal periodic function of the control voltage, a period of which is shown here. Depending on the desired harmonic content, the shape of the sinusoid may change.
• the microcontroller calculates and applies the coefficient k of a higher or lower value of the register in order to adapt the level of voltage applied to the motor phases. This results in a higher or lower phase current and therefore a higher or lower torque of the motor to adapt to the measured offset.
• the duration of the steps is determined by the duration of a period of tension divided by the total number of steps of a period.
• the duration width of each step is constant and identical.
• the width of step duration calculated and imposed by the microcontroller varies according to the desired speed of movement of the motor.
• each amplitude voltage value An, i * k is obtained from a constant voltage source by pulse width modulation (PWM) technique - adjusting the ratio cyclic.
• PWM pulse width modulation
• Fig. 15 shows the dynamic control change allowed by the present invention. It is plotted in the example presented, at the left ordinate, the evolution of the stator position (40) and the evolution of the measured position of the rotor (41) at an angle; at the right ordinate, the load value (53) at the rotor and the value of k (57) in a normed scale from 0 to 1.
• the abscissa shows the number of steps. The periodic slots observed are due to the difference in definition between the motor steps and the rotor position acquisition.
• the stator position (40) is zero, as is the value of k (57). From this rest position (initial moment), a constant load (53) of about 0.3 (normed value) is applied. Due to inertia and mechanical play, the rotor remains in the zero position. As the control is given to the motor to advance, the stator position (40) increases. so the load angle resulting from the difference of the stator positrons (40) and rotor (41) is insufficient to generate a torque greater than the load, no displacement is observed at the rotor. This results in an increase in the load angle and hence in the value of k (57) of the pitch PO up to pitch P7.
• the rotor speed synchronizes with the stator field (40) with an approximately constant load angle when the load is constant.
• the value of k remains around a value of 0.5 (normalized value) from pitch P7 to pitch P16.
• step P16 the load increased from about 0.3 to about 0.55 (norm value).
• the load angle increases until reaching a new value, which corresponds to an average value of 0.7 of k. This value remains almost constant until no P27.
• step P27 to step P40 the load decreased from about 0.55 to about 0.17.
• the load angle decreases, leading to a decrease of k to an average value of 0.4.
• FIG. 15 shows how the control dynamically modifies the value of k (and therefore the average current value flowing in the motor) as a function of the load which is applied to the rotor by the intrinsic relation between the load angle and the value of k.
• the exemplary function of FIG. 15 is in no way limiting but only given as an example of dynamic operation.
• the speed of the control defined by the voltage step duration is always constant, only the value of k and therefore the amplitude of voltage step and therefore the amplitude of current to the coils of the motor evolving according to from the load to the rotor.
• the invention also relates to a method of controlling a polyphase actuator according to the main claim for reducing the current consumption according to the following different steps:
• the alarm clock of the microcontroller as soon as the load angle exceeds a second fixed threshold, typically 80 °, then powering the motor phases in order to reduce the load angle until reaching the first threshold set.
• a second fixed threshold typically 80 °
• the invention also relates to a method of controlling a polyphase actuator according to the main claim for learning continuously or at will the mechanical play present in the actuator (by the possible existence of a mechanical gear inserted between the rotor of the actuator and the movable output member) and having the following steps: the training of the movable member in a first direction of movement along several steps Pi,
• the invention also relates to a method of controlling a polyphase actuator according to the main claim for predicting a maintenance requirement and having the following steps:
• the invention also relates to a method of controlling a polyphase actuator according to the main claim for producing a speed curve adapted to reach a mechanical stroke end (or stop) at a reduced speed and having the following steps:

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Stepping Motors (AREA)
• Control Of Electric Motors In General (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=62816750

Family Applications (1)

Country Status (7)

Family Cites Families (40)

• 2018
  • 2018-04-09 FR FR1853070A patent/FR3079983B1/fr active Active
• 2019
  • 2019-04-09 EP EP19721003.2A patent/EP3776841A1/de active Pending
  • 2019-04-09 WO PCT/FR2019/050832 patent/WO2019197775A1/fr unknown
  • 2019-04-09 JP JP2020555059A patent/JP2021520771A/ja active Pending
  • 2019-04-09 CN CN201980024411.5A patent/CN111937293A/zh active Pending
  • 2019-04-09 US US17/043,297 patent/US11621659B2/en active Active
  • 2019-04-09 KR KR1020207032220A patent/KR20200140366A/ko not_active Application Discontinuation

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