JP2013118782A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device that is capable of stabilizing a rotor at initial positions quickly before start of rotation.SOLUTION: A motor control device includes a rotation control part 4 for controlling rotation of a three-phase motor 2 by energizing a plurality of switching elements 31 to 36 based on a control signal, with the rotation control part 4 performing one-phase energization in order to move a predetermined portion 21a of the rotor 21 to initial positions A1 and A2 before start of the rotation of the motor. The rotation control part 4 energizes the switching elements so that the rotor 21 is electromagnetically braked in a period from start of the one-phase energization to end of fluctuation of the rotor 21 by the one-phase energization, thereby causing the predetermined portion 21a to stop within cogging angle ranges B1 and B2 corresponding to the initial positions A1 and A2.

Description

  The present invention relates to a motor control device that controls rotation of a motor.

  Examples of the motor include a three-phase motor including a stator having a stator coil and a rotor having a permanent magnet. The rotation of the three-phase motor is controlled by attraction and repulsion acting between the magnetic flux generated by energizing the stator coil and the magnetic flux of the permanent magnet. Some three-phase motors are brushless and sensorless. In this motor rotation control, as described in, for example, Japanese Patent Application Laid-Open No. 2005-90466 (Patent Document 1), one-phase energization is performed to move the position of the rotor before starting rotation to a predetermined initial position. Is done. The motor control device moves the rotor to the initial position by one-phase energization, performs normal energization control, and starts the three-phase motor from the initial position. The initial position is a position corresponding to (close to) the pole of the stator coil that is energized by one phase.

JP 2005-90466 A

  However, when the rotor is rotated by one-phase energization, the rotor gradually converges to the pole while swinging around the energized pole during energization. This takes time until the rotor is stabilized at the initial position, and there is a problem in realizing smooth and quick start-up.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a motor control device that can quickly stabilize a rotor at an initial position before starting rotation.

  The invention according to claim 1 includes a rotation control unit that controls the rotation of the three-phase motor by energizing a plurality of switching elements based on a control signal, and moves a predetermined portion of the rotor to an initial position before starting the rotation. In order to achieve this, the rotation control unit is a motor control device that performs one-phase energization, and a position where a predetermined portion of the rotor is stabilized in a non-excited state by a cogging torque generated in the rotor is defined as a cogging stable position. Assuming that a cogging angle range is an angle range in which a predetermined position of the rotor is set to a stable position and is not excited, the initial position includes a stator coil that is excited by the one-phase energization. The cogging stable position is close to one pole part, and the rotation control unit is configured to swing the rotor by the one-phase energization from the start of the one-phase energization. Until the motor stops, the switching element is energized so as to apply an electromagnetic brake to the rotor, and a predetermined portion of the rotor is stopped within the cogging angle range corresponding to the initial position. To do.

  According to a second aspect of the present invention, in the first aspect, the rotation control unit performs excitation by the one-phase energization at the start of the one-phase energization from the start of the one-phase energization to the application of the electromagnetic brake. It is weaker than excitation.

  The invention according to claim 3 includes a rotation control unit that controls the rotation of the three-phase motor by energizing the plurality of switching elements based on the control signal, and rotates a predetermined portion of the rotor to the initial position before starting the rotation. Therefore, the rotation control unit performs the one-phase energization between the start of the one-phase energization and the swing of the rotor due to the one-phase energization. The excitation is weaker than the excitation at the start of the one-phase energization.

  According to the first aspect of the present invention, after starting the one-phase energization, the predetermined portion of the rotor is stopped within the cogging angle range corresponding to the initial position by the electromagnetic brake. Thereby, in the non-excited state after the electromagnetic brake is released, the predetermined portion of the rotor moves to the initial position which is the cogging stable position and is stabilized. That is, according to the present invention, it is possible to stop the rotation of the rotor and to quickly stabilize the rotor at the initial position.

  According to the second aspect of the present invention, the vibration of the rotor can be converged at an early stage by switching the excitation to the weak excitation. By causing the peristaltic to converge at an early stage, the stop position at a predetermined position of the rotor by the electromagnetic brake can be quickly brought within the desired cogging angle range.

  According to the invention described in claim 3, by switching the excitation to weak excitation, the rotor can be prevented from swinging and converged at an early stage. That is, according to the present invention, the rotor can be quickly stabilized at the initial position before the rotation is started.

It is a block diagram which shows schematic structure of the motor control apparatus of this embodiment. It is a schematic cross section showing the section of the three phase motor of this embodiment typically. It is a time chart regarding the one-phase energization control of this embodiment. It is a flowchart regarding the one-phase energization control of this embodiment. It is a time chart regarding the 1 phase electricity supply control of the deformation | transformation aspect of this embodiment. It is a time chart regarding the 1 phase electricity supply control of the deformation | transformation aspect of this embodiment.

  Next, the present invention will be described in more detail with reference to preferred embodiments. The present embodiment is a control device for a sensorless brushless three-phase motor (here, a sensorless brushless DC motor). As shown in FIG. 1, the motor control device 1 of this embodiment includes a three-phase motor 2, a switching circuit unit 3, a rotation control unit 4, and a position detection unit 5.

  As shown in FIG. 2, the three-phase motor 2 mainly includes a rotor 21 having a permanent magnet 2 a and a stator 22 that generates a magnetic flux for applying a rotational force to the rotor 21. The stator has U-phase, V-phase, and W-phase three-phase stator coils 2U, 2V, and 2W. The stator coils 2U to 2W are connected by a Δ connection, and are connected to the switching circuit unit 3 by terminals 23 to 25. The stator 22 has pole portions 2U1, 2U2, 2V1, 2V2, 2W1, and 2W2 in which the stator coils 2U to 2W are respectively divided and wound. The pole portions 2U1 to 2W2 are arranged inside the stator 22 at equal intervals so as to face the rotor 21.

  The switching circuit unit 3 is connected to the three-phase motor 2, the rotation control unit 4, and the power source 9, and controls the three-phase motor 2. A DC voltage is supplied from the power source 9 to the switching circuit unit 3. The switching circuit unit 3 includes six switching elements, that is, high-side transistors 31, 33, and 35 connected to the positive terminal of the power source 9 and low-side transistors 32, 34, and 36 connected to the negative terminal of the power source 9. And is composed of. The switching circuit unit 3 sequentially applies a voltage between two of the three lines of the three-phase motor 2 based on a signal from the rotation control unit 4 to drive the three-phase motor 2 to rotate by a unit rotation angle. The transistors 31 to 36 of this embodiment are field effect transistors (FETs). Note that a corresponding diode may be provided for each of the transistors 31 to 36.

  The position detector 5 is connected to terminals 23 to 25 of the three-phase motor 2. The position detection unit 5 detects the position of the rotor 21 based on the comparison result between the counter electromotive force generated in each of the stator coils 2U to 2W and a preset reference voltage as the three-phase motor 2 rotates. The position detection unit 5 detects that the rotor 21 has reached a preset position. A known technique can be used for this detection, and a description thereof will be omitted. The position detection unit 5 transmits the detection result to the rotation control unit 4.

  The rotation control unit 4 is composed of a microcomputer and is connected to control terminals (bases) of the transistors 31 to 36. The rotation control unit 4 receives a control signal (for example, an operation command and a stop command) from, for example, a control unit 90 as a host system, and controls on / off of the transistors 31 to 36 based on the control signal. In other words, the rotation control unit 4 energizes the transistors 31 to 36 included in the switching circuit unit 3 based on the control signal.

  For example, when the rotation control unit 4 turns on only the transistors 31 and 34, current is supplied between the V-phase terminal 24 and the W-phase terminal 25. That is, in this case, a current flows between the terminals via the stator coil 2V by the power source 9, and a current flows between the terminals via the stator coils 2U and 2W. Similarly, when the rotation control unit 4 turns on only the transistors 33 and 32, current flows in the stator coil 2V and the stator coils 2U and 2W in the opposite direction to the above case.

  In each of the stator coils 2U to 2W, a magnetic flux corresponding to the direction in which the current flows is generated. The magnetic flux generates an attractive force or a repulsive force with the permanent magnet 2 a included in the rotor 21. The rotation control unit 4 controls the rotation of the rotor 21 by sequentially turning on the upper and lower paired transistors of the high side and the low side. The rotation control unit 4 outputs a PWM signal to the switching circuit unit 3 (executes PWM control) based on the detection result of the position detection unit 5.

  The rotation control unit 4 performs one-phase energization in order to move the position of the rotor 21 to the initial position before starting the rotation of the three-phase motor 2. In order to energize one of the three phases, the rotation control unit 4 energizes and turns on the control terminals of the transistors 35 and 34, for example. A current flows through the stator coil 2 </ b> W from the U-phase terminal 23 toward the W-phase terminal 25. Thereby, magnetic flux is generated in the stator coil 2W (pole portions 2W1, 2W2), and a predetermined portion of the rotor 21 moves toward the initial position. The pole portions 2U1 to 2W2 are provided at equal intervals in the circumferential direction on the stator 22, and each of the stator coils 2U to 2W is divided into two pole portions and arranged to face each other.

  The initial position is set to a predetermined cogging stable position. The initial position of this embodiment is set to two cogging stable positions A1 and A2 that are close to one pole portion 2W1 of the stator coil 2W that is energized by one-phase energization. The predetermined location 21a of the rotor 21 in the present embodiment is one location (location close to the pole 2W1) selected from the locations (12 locations) on the rotor 21 located at the cogging stable position in the non-excited state.

  Here, the cogging stable position will be described. First, the cogging torque is a force generated between the rotor 21 having a permanent magnet and the stator 22 and is generated at a predetermined cycle. The cogging torque pulsates by the least common multiple of the number of poles of the rotor 21 and the number of poles of the stator 22 (the number of pole portions around which the stator coil is wound) per one rotation of the motor. In the present invention, the number of poles (number of permanent magnets) of the rotor 21 is four, the number of poles (number of pole parts) of the stator 22 is six, and there are twelve cogging torque generating parts. The rotation angle at which cogging torque is generated is determined by the number of cogging torque generating portions and the like. In the present embodiment, since the cogging torque generation unit is 12, the predetermined rotation angle (cogging torque generation interval) is a constant 30 degrees (360 degrees / 12).

  The generation positions A1 to A12 where the cogging torque is generated are positions where the rotor 21 is attracted and stabilized in the non-excited state. That is, the cogging stable position is a position where the rotor 21 is stabilized in a non-excited state by the cogging torque (cogging torque generation positions A1 to A12). In other words, the predetermined portion 21a of the rotor 21 is stabilized at the cogging stable positions A1 to A12 in a non-excited state. As shown in FIG. 2, the cogging stable positions A1 to A12 of the present embodiment are arranged at intervals of about 30 degrees in the rotation angle.

  Each of the stable cogging positions A1 to A12 has an angle range that attracts the rotation angle of the rotor 21 to the position (rotation angle) of itself A1 to A12 in a non-excited state. In other words, each cogging stable position A <b> 1 to A <b> 12 has an angle range in which its cogging torque affects the rotor 21. This angle range is defined as a cogging angle range.

  In this embodiment, since cogging torque is generated at every predetermined rotation angle, as shown in FIG. 2, each cogging angle range B1 to B12 is 30 degrees around the corresponding cogging stable position A1 to A12 (cogging torque generation interval). ) Angle range. Specifically, for example, the cogging stable position A1 has a cogging angle range B1 that extends by 15 degrees (rotation angle that is half the cogging torque generation interval) in both rotation directions around A1 itself. When the predetermined portion 21a of the rotor 21 is located in the cogging angle range B1 in a non-excited state, the predetermined portion 21a is attracted to the cogging stable position A1 and moves, and is stabilized at the cogging stable position A1 (see FIG. 2).

(Control during single-phase energization)
The rotation control unit 4 controls the transistors 31 to 36 related to the one-phase energization so as to weaken the excitation related to the stator coils 2U to 2W after the start of the one-phase energization. That is, as shown in FIG. 3, the rotation control unit 4 switches the excitation to weak excitation that is weaker than the excitation at the start of the one-phase energization after the first predetermined time t <b> 1 has elapsed since the start of the one-phase energization. The strength of excitation (magnitude of magnetic flux density) is determined by the magnitude of the current flowing through the stator coils 2U to 2W, and the magnitude of the current can be changed by changing the magnitude of the voltage applied to the control terminals of the transistors 31 to 36, for example. Can do.

  The first predetermined time t1 is set to a time from the start of one-phase energization to the stop of the swing of the rotor 21. Here, the first predetermined time t1 of the present embodiment is set to a time from the start of one-phase energization until the rotor 21 overcomes static friction and starts rotating. Thereby, the swing (amplitude) of the rotor 21 can be minimized.

  Then, when the second predetermined time t2 (t2> t1) has elapsed from the start of the one-phase energization, the rotation control unit 4 controls the transistors 31 to 36 so as to apply the electromagnetic brake to the three-phase motor 2. Specifically, the rotation control unit 4 turns on only all the low-side transistors 32, 34, and 36.

  The second predetermined time t2 is a time longer than the first predetermined time t1, and is set so that the predetermined portion 21a of the rotor 21 is stopped within the cogging angle ranges B1 and B2 of the initial positions A1 and A2 by the electromagnetic brake. It ’s fine. Specifically, the second predetermined time t2 of the present embodiment is equal to or longer than the time required for the swing of the predetermined portion 21a of the rotor 21 to fall within the cogging angle ranges B1 and B2 of the initial positions A1 and A2. It is set to less than the time to stop. In other words, the second predetermined time t2 is a time that is longer than the time when the swinging width of the rotor 21 around the pole 2W1 caused by the one-phase energization is less than 60 degrees and shorter than the peristaltic stop time. 60 degrees is a value obtained by expanding the cogging angle range (B1, B2) in both rotation directions around the pole 2W1 excited by one-phase energization. That is, this angle range (60 degrees) is ± 30 degrees (cogging angle range) centered on the pole 2W1, and the angle range in which the predetermined portion 21a of the rotor 21 is attracted to the initial positions A1 and A2 in the non-excited state. means.

  The minimum value of the second predetermined time t2 can be obtained, for example, by calculating the time until the rotor 21 swings below 60 degrees assuming that the swing of the rotor 21 is maximized (condition). The second predetermined time t2 of the present embodiment is set to a time (that is, a minimum value) at which the rotor 21 swings less than 60 degrees under the above conditions. The second predetermined time t2 of the present embodiment is set to a time necessary for the predetermined portion 21a of the oscillating rotor 21 to be within the cogging angle ranges B1 and B2. The time during which the swing of the rotor 21 is within the cogging angle ranges B1 and B2 is estimated by experiments and simulations assuming a case where the swing is the largest in consideration of weak excitation conversion.

  Thus, the first predetermined time t1 and the second predetermined time t2 are set in consideration of the strength of excitation at the start of one-phase energization, the position of the predetermined portion 21a of the rotor 21 at the start of one-phase energization, and the like. . The first predetermined time t1 and the second predetermined time t2 can be estimated by performing experiments or simulations under worst conditions based on the motor load, motor characteristics, and motor inertia. Both the predetermined times t1 and t2 are times assumed by experiments or the like.

  As shown in FIG. 4, when the one-phase energization is started (S101), the rotation control unit 4 determines whether or not the first predetermined time t1 has passed (S102). When the first predetermined time t1 has elapsed (S102: Yes), the rotation control unit 4 switches the excitation to weak excitation (S103). When the second predetermined time t2 has elapsed (S104: Yes), the rotation control unit 4 controls the transistors 31 to 36 to apply the electromagnetic brake to the three-phase motor 2 (S105). Then, the rotation control unit 4 releases the electromagnetic brake and starts rotation control based on the control signal (S106).

  As described above, according to the motor control device 1 of the present embodiment, the excitation of the stator coils 2U to 2W is switched to the weak excitation after the first predetermined time t1 has elapsed from the one-phase energization. As a result, as shown in FIG. 5, the swing of the rotor 21 caused by the one-phase energization is quickly reduced, and the predetermined portion of the rotor 21 is easily converged to the initial positions A1 and A2.

  Furthermore, according to the present embodiment, the electromagnetic brake is applied after the second predetermined time t2 has elapsed since the one-phase energization. Thereby, the rocking | fluctuation of the rotor 21 which arises by one-phase electricity supply can be stopped compulsorily. Since the swing of the predetermined portion 21a of the rotor 21 is within a range of 60 degrees centering on the pole 2W1, when the electromagnetic brake is applied, the predetermined portion 21a of the rotor 21 is within the cogging angle range B1 of the initial position A1 or the initial position. Stop within the cogging angle range B2 of A2. That is, the rotation control unit 4 stops the predetermined portion 21a of the rotor 21 within the cogging angle ranges B1 and B2 corresponding to the initial positions A1 and A2 by the electromagnetic brake. Thereafter, when the electromagnetic brake is released, the predetermined portion 21a of the rotor 21 moves to and stabilizes at the initial position A1 when stopped within the cogging angle range B1, and at the initial position when stopped within the cogging angle range B2. Move to A2 and stabilize.

  As described above, according to the motor control device 1 of the present embodiment, the rotor 21 can be stopped after being suppressed from swinging due to the one-phase energization, and a predetermined portion of the rotor 21 can be stabilized at the initial position at an early stage.

(Modification)
The present invention is not limited to the above embodiment. For example, the rotation control unit 4 may perform control so as to apply an electromagnetic brake without switching the excitation to weak excitation after the start of one-phase energization. In this case, the circuit control unit 4 applies an electromagnetic brake to the three-phase motor 2 after the second predetermined time t2 has elapsed since the start of the one-phase energization. That is, the rotation control unit 4 is set to execute control except S102 and S103 in FIG. In this case, the second predetermined time t2 is estimated by an experiment or the like on the condition that there is no weak excitation switching. Also with this configuration, as shown in FIG. 5, the predetermined portion of the rotor 21 can be stabilized at the initial position at an early stage. However, by performing the weak excitation switching (S103) as in the present embodiment, the peristaltic motion can be suppressed and the peristaltic width can be suppressed within the cogging angle ranges B1 and B2 at an early stage. The certainty of stopping into the ranges B1 and B2 is improved.

  Further, the rotation control unit 4 may execute only weak excitation switching without starting an electromagnetic brake after the start of one-phase energization. That is, the rotation control unit 4 may be set to execute control excluding S104 and S105 in FIG. Also with this configuration, as shown in FIG. 6, the predetermined portion of the rotor 21 can be stabilized at the initial position at an early stage. The dotted line in FIG. 6 represents the oscillation of the rotor 21 when there is no weak excitation switching, and the solid line in FIG. 6 represents the oscillation of the rotor 21 when there is weak excitation switching (a variation of this embodiment).

  The rotation control unit 4 may gradually weaken the excitation when switching the excitation to weak excitation. Further, the rotation control unit 4 may perform weak excitation switching immediately after the start of one-phase energization (the first predetermined time t1 is close to 0).

  Further, the connection of the stator coil 2 may be a star connection. Further, when the pole portion excited by the one-phase energization is at the same position (same rotation angle) as the cogging stable positions A1 to A12 (for example, in the case of star connection), the cogging stable position at the same position as the pole portion is the initial position. Position. For example, when the pole portion 2W1 and the cogging stable position A1 are at the same position, the initial position is the cogging stable position A1. In this case, the second predetermined time t2 is set to be equal to or longer than the time during which the peristaltic movement of the predetermined portion 21a of the rotor 21 is within a 30-degree range (cogging angle range B1) centering on the pole portion 2W1, and less than the peristaltic stop time. This angle range (30 degrees) is ± 15 degrees (half-cogging angle range) centered on the pole 2W1, and means an angle range in which the predetermined portion 21a of the rotor 21 is attracted to the initial position A1 in a non-excited state.

  In the present specification, “proximity” is used to mean including the same position (same rotation angle: same phase). In addition, for the sake of explanation, the predetermined location 21a of the rotor 2 is defined. As a result, the predetermined location 21a may be moved to the initial positions A1 and A2 by one-phase energization, and the rotor 21 is based on the rotation angle (phase) of the rotor 21. May be defined.

  Further, the second predetermined time t2 may be set to a time at which the predetermined portion 21a first reaches the cogging angle ranges B1 and B2 when the swing of the predetermined portion 21a of the rotor 21 is maximized. As a result, the predetermined portion 21a is located within the cogging angle ranges B1 and B2 at the elapse of the second predetermined time t2 regardless of the position when the one-phase energization is started. Can be stopped within. Also in this case, the second predetermined time t2 can be calculated by experiments or the like according to the presence or absence of weak excitation switching. However, in terms of certainty of stopping within the cogging angle ranges B1 and B2, the present embodiment in which the electromagnetic brake is applied after the weak excitation switching is more advantageous. The first predetermined time t1 assumes that the predetermined location of the rotor 21 is at a position farthest from the initial positions A1 and A2 (a position having the maximum amplitude), and the predetermined location of the rotor 21 is within the cogging angle range B1, You may set to the time until it enters in B2.

1: motor control device,
2: 3-phase motor, 21: rotor, 22: stator,
2U, 2V, 2W: stator coil,
2U1, 2U2, 2V1, 2V2, 2W1, 2W2: pole part,
3: switching circuit part, 31-36: transistor (switching element),
4: rotation control unit, 5: position detection unit,
A1 to A12: Cogging stable position, B1 to B12: Cogging angle range

Claims (3)

A rotation control unit that controls the rotation of the three-phase motor by energizing a plurality of switching elements based on a control signal is provided, and the rotation control unit is configured to move a predetermined portion of the rotor to an initial position before starting the rotation. A motor control device that performs phase energization,
A position where a predetermined portion of the rotor is stabilized in a non-excited state due to a cogging torque generated in the rotor is defined as a cogging stable position, and the predetermined portion of the rotor is attracted to the cogging stable position in each of the cogging stable positions. If the angle range to be obtained is the cogging angle range
The initial position is the cogging stable position close to one pole portion where the stator coil excited by the one-phase energization is disposed,
The rotation control unit energizes the switching element so as to apply an electromagnetic brake to the rotor from the start of the one-phase energization until the swing of the rotor due to the one-phase energization stops. A motor control device that stops the predetermined portion within the cogging angle range corresponding to the initial position. In claim 1,
The rotation control unit is a motor control device that weakens excitation by the one-phase energization from excitation at the start of the one-phase energization between the start of the one-phase energization and the application of the electromagnetic brake. A motor that includes a rotation control unit that controls the rotation of a three-phase motor by energizing a plurality of switching elements based on a control signal, and that performs one-phase energization to rotate a predetermined portion of the rotor to an initial position before the rotation starts. A control device,
The rotation control unit performs motor control to weaken excitation by the one-phase energization from excitation at the start of the one-phase energization between the start of the one-phase energization and the stop of the swing of the rotor by the one-phase energization. apparatus.

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