Control device, control method and brushless motor

Abstract

The present invention provides a control device, a control method and a brushless motor. The control device has a control unit, which controls the voltage and current applied to each of the multiple phases of the brushless motor through vector control. When the rotation of the rotor is controlled, the vector control is performed by using the rotation control mainly based on the q-axis current, and when a stop command signal is received, the excitation fixed control is performed mainly based on the d-axis current. In the excitation fixed control, the control unit suppresses the influence of the dead time when the high-side switching elements and low-side switching elements constituting the multiple half-bridge circuits are set to be disconnected to control the brushless motor. The multiple half-bridge circuits are set corresponding to each of the multiple phases of the brushless motor to provide voltage and current to each phase.

Description

Technical Field

[0001] The present disclosure relates to a control device, a control method and a brushless motor. Background Art

[0002] Japanese Patent Gazette No. 2017-22867 describes a motor driving method comprising the following steps: setting power-on, that is, before the motor starts, using two-phase power-on to generate a fixed magnetic field for a certain period of time to position the rotor at a position that deviates from the zero point by a phase difference of 30°; performing starting power-on with 1-phase 180° power-on, that is, selecting an interval that advances one interval in the direction of travel from the set theoretical stop position from the 1-phase 60° bipolar rectangular wave power-on mode and performing power-on; and completing the starting power-on by detecting the zero point that is 90° ahead of the theoretical stop position of the rotor in phase, and then performing the 1-phase 60° bipolar rectangular wave power-on by detecting the zero point at each phase difference of 60°.

[0003] The following motor drive device is described in Japanese Patent Gazette No. 2014-217113, which comprises: an inverter having a plurality of switching elements, which outputs driving power to the motor by turning these switching elements on and off; and a control unit, which, when starting the motor, performs PWM control on each switching element to cause a specified excitation current to flow through each phase winding of the motor to rotate the rotor of the motor to an initial position, and the control unit switches the initial position of the rotor each time the motor is started.

[0004] Japanese Patent Gazette No. 2018-98915 describes a method for correcting the excitation position error of an electric motor as follows: multiply the first measurement value or the second measurement value measured when an offset error occurs in each power-on mode during position detection of permanent magnet excitation by a correction coefficient A, and obtain a correction value that corrects the offset error. The position of permanent magnet excitation is estimated based on the correction value.

[0005] In addition, in the control device of the brushless motor, the voltage and current applied to the motor are controlled by controlling the on / off of the high-side switch element and the low-side switch element of the half-bridge circuit. At this time, due to the dead time to prevent the high-side switch element and the low-side switch element from being turned on at the same time, errors may occur in the voltage and current applied to the brushless motor, thereby causing errors in the position control of the brushless motor, increased current consumption, increased speed variation, etc. Summary of the invention

[0006] An object of the present disclosure is to provide a control device and a control method for a brushless motor, and a brushless motor that suppress the influence of a dead time.

[0007] According to the first scheme of the present disclosure, a control device is provided, wherein the control device has a control unit, and the control unit controls the voltage and current applied to each phase of a plurality of phases of a brushless motor by vector control. When the rotation of the rotor is controlled, the vector control is performed by using rotation control mainly based on q-axis current, and when a stop command signal is received, the vector control is performed by using excitation fixing control mainly based on d-axis current. In the excitation fixing control, the control unit suppresses the influence of dead time in which high-side switching elements and low-side switching elements constituting a plurality of half-bridge circuits are set to be disconnected to control the brushless motor. The plurality of half-bridge circuits are arranged corresponding to each phase of the plurality of phases of the brushless motor to provide voltage and current to each phase.

[0008] According to the second scheme of the present disclosure, the control device has an acquisition unit, which acquires rotation information indicating the rotation amount and rotation direction of the rotor of the brushless motor. When the control unit aligns the position of the rotor of the brushless motor with the initial position of the electrical angle in the vector control during the excitation fixed control, the control unit sets the following electrical angle: the electrical angle avoids the electrical angle at which the voltage applied to any phase of the multiple phases of the brushless motor becomes a voltage near zero crossing, and calculates the electrical angle corresponding to the position of the rotor based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor.

[0009] According to the third scheme of the present disclosure, the control device has an acquisition unit, which acquires rotation information indicating the rotation amount and rotation direction of the rotor of the brushless motor. When the position of the rotor of the brushless motor is aligned with the initial position of the electrical angle in the vector control during the excitation fixed control, the control unit sets the electrical angle so that the voltage applied to any phase of the multiple phases of the brushless motor becomes the voltage with the largest absolute value, and calculates the electrical angle corresponding to the position of the rotor based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor.

[0010] According to the fourth scheme of the present disclosure, when the rotor rotates according to the set electrical angle, and when the rotation amount of the rotation information obtained from the acquisition unit becomes greater than a predetermined amount, the control unit resets the electrical angle that is closest to the direction opposite to the rotation direction of the rotor and makes the voltage of any phase among the multiple phases become the electrical angle with the largest absolute value to perform initial position alignment.

[0011] According to the fifth aspect of the present disclosure, after the initial position alignment is completed, the control unit returns the position of the rotor to the position before the initial position alignment was performed.

[0012] According to a sixth aspect of the present disclosure, the control unit sets the voltage applied to each of the plurality of phases of the brushless motor to a voltage obtained by correcting the voltage in the rotation control in the field fixing control.

[0013] According to the seventh scheme of the present disclosure, the control device has an acquisition unit, which acquires rotation information indicating the rotation amount and rotation direction of the rotor of the brushless motor, and when the rotor stops, if there is a deviation between the position of the rotor obtained according to the rotation information acquired by the acquisition unit and the electrical angle of the instruction, the control unit corrects the electrical angle accordingly.

[0014] According to the 8th scheme of the present disclosure, when the rotor stops by the excitation fixing control, the control unit reduces the d-axis current if the deviation between the position of the rotor obtained according to the rotation information obtained by the acquisition unit and the electrical angle of the instruction is below or less than a predetermined range, and increases the d-axis current if the deviation between the position of the rotor and the electrical angle of the instruction exceeds a predetermined range.

[0015] According to the 9th scheme of the present disclosure, the control device has an acquisition unit, which acquires rotation information indicating the rotation amount and rotation direction of the rotor of the brushless motor. When the rotor stops by the excitation fixing control, the control unit reduces the d-axis current if the deviation between the position of the rotor obtained according to the rotation information acquired by the acquisition unit and the electrical angle of the instruction is below a predetermined range or less than a predetermined range, and increases the d-axis current if the deviation between the position of the rotor and the electrical angle of the instruction exceeds a predetermined range.

[0016] According to the 10th scheme of the present disclosure, a control device is provided, wherein the control device has a control unit, and the control unit controls the voltage and current applied to each phase of a plurality of phases of a brushless motor by vector control, and the vector control is performed by utilizing rotation control mainly based on q-axis current when controlling the rotation of the rotor, and is performed by utilizing excitation fixing control mainly based on d-axis current when receiving a stop command signal, and the control unit controls the brushless motor by suppressing the influence of dead time in which high-side switching elements and low-side switching elements constituting a plurality of half-bridge circuits are both set to be disconnected by correcting the voltage applied to each phase of the plurality of phases of the brushless motor, and the plurality of half-bridge circuits provide voltage and current to each phase.

[0017] According to an eleventh aspect of the present disclosure, there is provided a control device comprising:

[0018] an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of a rotor of the brushless motor; and

[0019] a control unit that controls the voltage and current applied to each of the plurality of phases of the brushless motor by vector control, wherein the vector control is performed by rotation control mainly using the q-axis current when controlling the rotation of the rotor, and is performed by excitation fixing control mainly using the d-axis current when receiving a stop command signal,

[0020] When the rotation speed of the rotor obtained based on the rotation information obtained by the acquisition unit is below or lower than a predetermined rotation speed, the control unit controls the brushless motor by correcting the voltage applied to each of the multiple phases of the brushless motor to a target voltage.

[0021] According to a twelfth aspect of the present disclosure, there is provided a brushless motor comprising: the control device; a rotor; and a plurality of coils arranged around the rotor in correspondence with a plurality of voltages and currents to which the voltages and currents controlled by the control device are applied.

[0022] According to a 13th aspect of the present disclosure, there is provided a control method, wherein:

[0023] The voltage and current of each phase of the brushless motor are controlled by vector control. When the rotation of the rotor is controlled, the vector control is performed by rotation control mainly based on the q-axis current, and when a stop command signal is received, the excitation fixing control is performed mainly based on the d-axis current.

[0024] In the excitation fixed control, the brushless motor is controlled by suppressing the influence of the dead time in which the high-side switching elements and the low-side switching elements that constitute the multiple half-bridge circuits are set to be disconnected. The multiple half-bridge circuits are arranged corresponding to each of the multiple phases of the brushless motor to provide voltage and current to each phase.

[0025] (Effect)

[0026] According to the first, tenth and thirteenth aspects, the influence of the dead time can be suppressed.

[0027] According to the second aspect, compared with the case where the initial position alignment of the brushless motor is performed without limiting the electrical angle, the occurrence of errors in the initial position alignment of the brushless motor can be suppressed.

[0028] According to the third aspect, compared with the case where the electrical angle is not set so as to obtain the voltage with the maximum absolute value, the occurrence of errors can be further suppressed.

[0029] According to the fourth aspect, the amount of rotation of the rotor during initial positioning can be reduced compared to a case where the closest electrical angle is not set.

[0030] According to the fifth aspect, compared with the case where the position is not returned, it is possible to restart from the position where the rotor stopped.

[0031] According to the sixth aspect, compared with a case where the voltage is not corrected, it is possible to suppress the occurrence of an error in the initial position alignment of the brushless motor.

[0032] According to the seventh aspect, the accuracy of the rotor position control is improved compared to a case where the electrical angle is not corrected.

[0033] According to the eighth and ninth aspects, the power consumption can be suppressed while maintaining the position accuracy of the rotor.

[0034] According to the eleventh aspect, compared with a case where correction is performed independently of the rotation speed, the calculation load of the control device can be reduced.

[0035] According to the twelfth aspect, it is possible to provide a brushless motor in which the influence of the dead time is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a diagram showing an example of the overall structure of a brushless motor to which the first embodiment is applied.

[0037] Figure 2 This is a diagram showing an example of the structure of a motor.

[0038] Figure 3 This is a diagram showing an example of three-phase currents flowing through the coils of the stator.

[0039] Figure 4 is a diagram showing the rotor rotating in the motor. (a) is the flow through Figure 3 (b) is the state of the current at an electrical angle of 0°, (c) is the state where the rotor starts to rotate, and (d) is the state where the rotor starts to rotate.

[0040] Figure 5 This is a diagram for explaining a motor driver unit that applies a voltage to each phase of a motor in a motor control device.

[0041] Figure 6 This is a diagram showing an example of the relationship between the target voltage set for each phase of the motor, the current flowing through each phase of the motor, and the rotation amount of the motor's rotating shaft. (a) is the target voltage set for each phase of the motor, (b) is the current flowing through each phase of the motor, and (c) is the rotation amount of the motor's rotating shaft.

[0042] Figure 7 : is a figure which shows the hardware structure of the motor control device.

[0043] Figure 8This is a diagram showing an example of a functional configuration of a motor control device to which the first embodiment is applied.

[0044] Fig. 9 1 and 2 are diagrams for explaining the initial position alignment in the first embodiment. (a) is the current flowing through each phase of the motor, (b) is the d-axis current, and (c) is the position of the rotor.

[0045] Fig.10 These are diagrams for explaining the initial position alignment in the third embodiment. (a) is the current flowing through each phase of the motor, (b) is the d-axis current, and (c) is the position of the rotor.

[0046] Fig.11 This is a diagram showing an example of a functional configuration of a motor control device to which the fourth embodiment is applied.

[0047] Fig.12 The following are diagrams showing the waveform of the target voltage provided by the coordinate conversion unit and the waveform of the correction voltage after correction by the dead time correction unit. (a) is the waveform of the target voltage provided by the coordinate conversion unit, and (b) is the waveform of the correction voltage after correction by the dead time correction unit.

[0048] Fig.13 This is a diagram showing an example of the relationship between the correction voltage set for each phase of the motor, the current flowing through each phase of the motor, and the rotation amount of the motor's rotating shaft. (a) is the correction voltage set for each phase of the motor, (b) is the current flowing through each phase of the motor, and (c) is the rotation amount of the motor's rotating shaft.

[0049] Fig.14 This is a diagram showing a timing chart for controlling the rotation of a motor by applying the motor control device according to the fourth embodiment.

[0050] Fig.15 This is a diagram showing an example of a functional configuration of a motor control device to which the fifth embodiment is applied.

[0051] Fig.16 This is a diagram showing an example of a functional configuration of a motor control device to which the sixth embodiment is applied.

[0052] Fig.17 This is a diagram showing an example of a functional configuration of a motor control device to which the seventh embodiment is applied.

[0053] Fig.18 This is a diagram showing a timing chart for controlling the rotation of a motor by applying the motor control device according to the seventh embodiment.

[0054] Fig.19 This is a diagram showing an example of a functional configuration of a motor control device to which the eighth embodiment is applied.

[0055] Fig. 20This is a diagram showing a timing chart for controlling the rotation of a motor by applying the motor control device according to the eighth embodiment. DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0057] A brushless motor is a motor that uses a permanent magnet as a rotor (also called a rotor) and multiple coils arranged around the rotor as a stator (also called a stator). The current flowing through each coil is changed to generate a rotating magnetic field, which causes the rotor to rotate. In addition, a brushless motor can also be a structure in which a rotor is arranged around a stator. Here, it is explained that a brushless motor has a stator arranged around the rotor.

[0058] [First embodiment]

[0059] Figure 1 This is a diagram showing an example of the overall structure of the brushless motor 1 to which the first embodiment is applied.

[0060] The brushless motor 1 has a motor 10, an encoder 20 and a motor control device 30. The motor 10 has a rotor, a stator and a rotating shaft. The rotating shaft is fixed to the rotor and rotates together with the rotor. A load 2 is mounted on the rotating shaft. The load 2 is a mechanical element such as a gear, a cam and a roller, which rotates together with the rotating shaft to transmit power. The encoder 20 is a device that outputs a rotation signal indicating the rotation direction and rotation amount of the rotor.

[0061] The encoder 20 is, for example, a transmission-type optical encoder, and is provided with a circular plate with a slit, a light source, and a light receiving sensor. The circular plate has slits arranged at equal intervals along the circumference. In the encoder 20, light from the light source passes through the slits of the circular plate and is received by the light receiving sensor. That is, the circular plate rotates together with the rotor, whereby the light receiving sensor receives the light passing through the slits of the circular plate in a pulsed form. By setting a dual system of slit columns (called channels) of phase A and phase B, the pulse that rises first among the pulses of phase A and phase B represents the direction of rotation, and the number of pulses per unit time represents the amount of rotation. Here, the rotation signal representing the direction of rotation and the amount of rotation, which is the output of the encoder 20, is an example of rotation information.

[0062] The motor control device 30 is a computer that controls the rotation of the motor 10 (specifically, the rotation of the rotor) using the rotation signal output from the encoder 20 .

[0063] Figure 2 1 is a diagram showing an example of the structure of the motor 10 .

[0064] The motor 10 has a rotor 11, a stator 12, and a rotating shaft 14. The rotating shaft 14 is fixed to the rotor 11. The rotor 11 is a permanent magnet having a set of magnetic poles (N pole and S pole). The stator 12 has three coils 13 (described as coils 13u, 13v, and 13w when distinguished from each other). The coils 13 are arranged at positions that are offset from each other by 120° in the direction from the rotating shaft 14 toward each coil 13. One end of the winding of each coil 13 is connected to a motor driver unit (described later). Figure 5 The motor driver unit 311) is connected, and the other ends are connected to each other.

[0065] In the following, for the sake of convenience, the direction in which the coil 13u is arranged with the rotating shaft 14 as the center is described as the 0° direction (also called the upward direction), the opposite side thereof is described as the 180° direction (also called the downward direction), and the direction of the direction at an angle of 90° relative to them, which is close to the coil 13w, is described as the 270° direction (also called the left direction), and the direction of the direction close to the coil 13v is described as the 90° direction (also called the right direction). In this case, the coil 13u is arranged in the 0° direction, the coil 13v is arranged in the 120° direction, and the coil 13w is arranged in the 240° direction. The motor 10 is a three-phase motor as follows: the rotor 11 is rotated by passing three-phase currents (U phase, V phase, W phase) each shifted by 120° through the three coils 13.

[0066] Here, as an example, in the motor 10, the rotor 11 is set as a permanent magnet having one set of magnetic poles, but the rotor 11 may be a permanent magnet having multiple sets of magnetic poles. Similarly, the stator 12 is set to have three coils 13, but it may have coils exceeding 3 multiples of 3.

[0067] Figure 3 1 is a diagram showing an example of three-phase current flowing through the coil 13 of the stator 12. Figure 3 In the figure, the vertical axis represents the current (A) and the horizontal axis represents the electrical angle (°). The electrical angle refers to the phase (position in the cycle) when one cycle of the sinusoidal current is set to 360° (2π radians). Here, the electrical angle is the electrical angle relative to the d-axis direction in vector control. In addition, the d-axis direction refers to the direction in which the N pole of the rotor 11 faces.

[0068] In this example, the U-phase current (the current flowing in the coil 13u) is "-F1" at an electrical angle of 0°, "0" at 90°, "F1" at 180°, "0" at 270°, and "-F1" again at 360°. The V-phase current (the current flowing in the coil 13v) is "0" at an electrical angle of 30°, "-F1" at 120°, "0" at 210°, "F1" at 300°, and "0" again at 390°. The W-phase current (the current flowing in the coil 13w) is "F1" at an electrical angle of 60°, "0" at 150°, "-F1" at 240°, "0" at 330°, and "F1" again at 450°.

[0069] Figure 4 1 is a diagram showing a state in which the rotor 11 rotates in the motor 10 . Figure 4 (a) is flowing through Figure 3 The state of the current at an electrical angle of 0°, Figure 4 (b) is the state where the rotor 11 starts to rotate. Figure 4 (c) is the state where the rotor 11 starts to rotate. Figure 4 In (a), the N pole of the rotor 11 is oriented toward Figure 2 The 0° direction of the motor 10 defined in , and the S pole faces the 180° direction of the motor 10.

[0070] like Figure 4 As shown in (a), current flows through coil 13 Figure 3 When the current flows at an electrical angle of 90°, current flows through the V phase and the W phase. Therefore, the current of the V phase flows through the coil 13v, and the current of the W phase flows through the coil 13w. In addition, the current of the U phase is "0", so no current flows through the coil 13u. Therefore, a magnetic field is formed with the 270° side of the motor 10 as the N pole and the 90° side as the S pole. Figure 4 As shown in (b), the N pole of the rotor 11 is attracted by the S pole of the magnetic field formed, and the S pole of the rotor 11 is attracted by the N pole of the magnetic field formed. As a result, the rotor 11 starts to rotate in the clockwise direction. The clockwise direction here refers to the direction from coil 13u through coil 13v toward coil 13w (indicated by Figure 2 The angle of the direction described in the figure gradually increases). Then, as Figure 4 As shown in (c), when the rotor 11 starts to rotate, and as Figure 3When the electrical angle changes as shown, and thus the current flowing through the coil 13 changes, the N pole and the S pole of the magnetic field formed by the current also rotate in the clockwise direction. The rotating magnetic field is described as a rotating magnetic field. As a result, the N pole and the S pole of the rotor 11 are respectively attracted by the S pole and the N pole of the rotating magnetic field and rotate. That is, a rotating magnetic field is formed by the current flowing through the coil 13, and the N pole and the S pole of the rotor 11 are respectively continuously attracted by the rotating magnetic field, thereby rotating the rotor 11 of the motor 10. That is, the motor 10 rotates. The current flowing through the coil 13 is controlled by the motor control device 30.

[0071] As described above, when the motor 10 includes the rotor 11 including one set of magnetic poles and the three coils 13 through which three-phase currents flow, the position of the rotor 11 coincides with the electrical angle.

[0072] Figure 5 The motor driver unit 311 (see below) in the motor control device 30 for applying voltage to each phase of the motor 10 is described. Figure 8 Here, the PWM conversion unit 317 (refer to the following) that provides a pulse width modulation signal (hereinafter referred to as a PWM (Pulse Width Modulation) signal) to the motor 10, the encoder 20, and the motor driver unit 311 is also shown. Figure 8 ). The PWM signal is a pulse signal that repeatedly turns the voltage on and off, and applies a voltage corresponding to the width of the on pulse.

[0073] The motor driver unit 311 includes a half-bridge circuit 40 (when distinguished, it is described as a half-bridge circuit 40u, 40v, 40w) for supplying voltage to the U phase, V phase, and W phase of the motor 10, respectively. Each half-bridge circuit 40 includes a p-channel FET 41 and an n-channel FET 42 connected in series. In addition, the connection point of the p-channel FET 41 and the n-channel FET 42 in each half-bridge circuit 40 (the connection point of the drain side of the p-channel FET 41 and the drain side of the n-channel FET 42) is connected to each phase of the motor 10. That is, the connection point of the half-bridge circuit 40u is connected to the U phase of the motor 10, the connection point of the half-bridge circuit 40v is connected to the V phase of the motor 10, and the connection point of the half-bridge circuit 40w is connected to the W phase of the motor 10. In addition, a feedback diode 43 is connected in parallel to the p-channel FET 41, and a feedback diode 44 is connected in parallel to the n-channel FET 42. The source side of the p-channel FET 41 is connected to the power supply, and the source side of the n-channel FET 42 is grounded via a resistor R. The current i (when distinguished, described as current iu, iv, iw) flowing through each half-bridge circuit 40 is detected by the resistor R. In addition, feedback diodes 43 and 44 are provided to feed back the energy accumulated in the coil 13 connected to the half-bridge circuit 40 to the power supply. In addition, the p-channel FET 41 is an example of a high-side switching element, and the n-channel FET 42 is an example of a low-side switching element.

[0074] The PWM conversion unit 317 supplies a PWM signal to the gate of the p-channel FET 41 and the gate of the n-channel FET 42 in each half-bridge circuit 40. That is, the PWM conversion unit 317 applies a voltage VH (described as voltages VHu, VHv, and VHw when distinguished) as a PWM signal to the gate of the p-channel FET 41, and applies a voltage VL (described as voltages VLu, VLv, and VLw when distinguished) as a PWM signal to the gate of the n-channel FET 42. The p-channel FET 41 and the n-channel FET 42 in each half-bridge circuit 40 are set to be turned on / off by the supplied PWM signal. Then, a voltage is applied to each phase of the motor 10 by the turned-on p-channel FET 41 and the n-channel FET 42, and a current flows through the coil 13 in the stator 12. In addition, for each half-bridge circuit 40, the ratio (duty ratio) of the turned-on period and the turned-off period is switched and set, and thereby, as an average value, a current flows through each phase of the motor 10. Figure 3The current of the sine wave shown in FIG. 1 is a current of a sine wave. For example, when the p-channel FET 41 of the half-bridge circuit 40u is turned on and the n-channel FET 42 of the half-bridge circuit 40v is turned on, the current flows through the p-channel FET 41 of the half-bridge circuit 40u, the coil 13u, the coil 13v, and the n-channel FET 42 of the half-bridge circuit 40v. At this time, in the coil 13u, the current flows from one end to the other end, and in the coil 13v, the current flows from the other end to one end. Here, for the current flowing through the coil 13, the current flowing from one end to the other end is set to positive, and the current flowing from the other end to one end is set to negative.

[0075] In the half-bridge circuit 40, when the p-channel FET 41 and the n-channel FET 42 connected in series are turned on at the same time, a current flows from the power supply of the half-bridge circuit 40 to the ground. This current is sometimes called a through current. Therefore, in order to suppress the p-channel FET 41 and the n-channel FET 42 from being turned on at the same time (flow of a through current), a period in which both the p-channel FET 41 and the n-channel FET 42 are turned off, that is, a so-called dead time, is provided between the period in which the p-channel FET 41 is turned on and the period in which the n-channel FET 42 is turned on.

[0076] Figure 6 The diagram shows an example of the relationship between the target voltage (Vv, Vu, Vw) set for each phase of the motor 10 , the current flowing through each phase of the motor 10 , and the rotation amount of the rotating shaft 14 of the motor 10 . Figure 6 (a) is the target voltage set for each phase of the motor 10, Figure 6 (b) is the current flowing through each phase of the motor 10, Figure 6 (c) is the rotation amount of the rotating shaft 14 of the motor 10. Here, the horizontal axis is time. In addition, Figure 6 The dashed line in (c) shows an ideal case where the rotation amount of the rotating shaft 14 of the motor 10 changes in proportion to time.

[0077] Figure 6 The target voltage (Vv, Vu, Vw) set for each phase of the motor 10 shown in (a) is set in a step-like manner so as to be approximated to a sine wave. That is, the motor driver unit 311 causes the voltages applied to the U phase, V phase, and W phase of the motor 10 to gradually change over time. As a result, current flows through the U phase, V phase, and W phase of the motor 10, and the rotor 11 of the motor 10 rotates. However, in Figure 6 The current flowing through each phase (U, V, W) of the motor 10 shown in (b) is not approximately a sine wave. Figure 6 In (b), Figure 6The portion where the target voltage Vw intersects 0V (denoted as α), the portion where the target voltage Vu intersects 0V (denoted as β), and the portion where the target voltage Vv intersects 0V (denoted as γ) in (a) deviate greatly from the sine wave.

[0078] Therefore, if Figure 6 As shown in (c), the rotation amount of the rotating shaft 14 deviates from the rotation amount of the ideal rotating shaft 14 shown by the dot-dash line. Figure 6 In (c), Figure 6 The portion where the target voltage Vw intersects with 0V (denoted as α), the portion where the target voltage Vu intersects with 0V (denoted as β), and the portion where the target voltage Vv intersects with 0V (denoted as γ) in (a) deviate greatly from the sine wave. In addition, the case where the target voltage intersects with 0V or the case where the current intersects with 0A is sometimes described as zero crossing.

[0079] As described above, if Figure 6 As shown in (a), even if the target voltage set for each phase of the motor 10 is set in a stepwise manner in a manner that approximates a sine wave, a current that approximates a sine wave does not flow through each phase of the motor 10. Therefore, in the motor 10, an error may occur in the position control of the rotor 11, or the power consumption may increase or the rotation speed of the rotor 11 may change because the rotor 11 is not in a predetermined position. This situation is caused by the dead time that prevents the high-side switching element (p-channel FET41) and the low-side switching element (n-channel FET42) from being turned on at the same time.

[0080] Figure 7 3 is a diagram showing a hardware configuration of the motor control device 30. The motor control device 30 includes a CPU 31, a ROM 32, a RAM 33, an input / output interface (hereinafter referred to as an input / output IF) 34, a communication interface (hereinafter referred to as a communication IF) 35, and a bus 36. The CPU 31, the ROM 32, the RAM 33, the input / output IF 34, and the communication IF 35 are connected via the bus 36. Although not shown, the motor control device 30 may also include an HDD. The HDD is also connected to the bus 36.

[0081] The input / output IF 34 is connected to the motor driver 311. The motor driver 311 is connected to the motor 10. Furthermore, the input / output IF 34 is connected to the encoder 20. The communication IF 35 is connected to other control devices (or CPU) not shown. In addition, the portion surrounded by the dotted line is an example of a control unit.

[0082] When the power is turned on, the CPU 31 reads the program and data stored in the ROM 32 (or HDD), expands them to be executable on the RAM 33, and writes them to the RAM 33. Then, the program is executed. As the program is executed, data is exchanged with the RAM 33, the input / output IF 34, the communication IF 35, etc.

[0083] The input / output IF 34 supplies voltage to each phase of the motor 10 via the motor driver unit 311, and obtains each pulse of the A phase and the B phase from the encoder 20. The communication IF 35 obtains the rotation start / rotation stop command of the motor 10 and the command related to the control of the rotation speed, the stop position, etc. (sometimes described as a command value) from other control devices. In addition, the communication IF 35 outputs the state of the rotation start / rotation stop of the motor 10 and the information related to the state of the rotation speed, the stop position, etc. (sometimes described as data) to other control devices.

[0084] ROM 32 (or HDD) is, for example, EPROM, EEPROM, flash memory, etc., and stores programs, constants used by the programs, initial values ​​of variables, etc. RAM 33 may also be a rewritable nonvolatile memory such as flash memory.

[0085] Figure 8 1 is a diagram showing an example of the functional structure of the motor control device 30 to which the first embodiment is applied. The motor control device 30 includes a timer control unit 301, an instruction signal acquisition unit 302, a target speed setting unit 303, an encoder output acquisition unit 304, a rotation speed calculation unit 305, a speed control unit 306, a position control unit 307, a PWM conversion unit 317, a current detection unit 312, a current conversion unit 313, a q-axis current control unit 314, a d-axis current control unit 315, a coordinate conversion unit 316, a control switching unit 320, a first switching unit 321, a second switching unit 322, a third switching unit 323, and a fourth switching unit 324. In addition, each unit such as the timer control unit 301 is described as a functional unit.

[0086] The brushless motor 1 is controlled by rotation control for rotating the rotor 11 at a predetermined rotation speed and excitation fixing control when the rotation of the brushless motor 1 is started or the rotor 11 is set to a stop position by power on. In particular, the brushless motor 1 does not have a sensor for detecting the position of the rotor 11 (here, the direction in which the N pole of the rotor 11 is facing). Therefore, after the power is turned on, the position of the rotor 11 is made consistent with the controlled electrical angle by excitation fixing control. This is described as initial position alignment. After the initial position alignment, rotation control for controlling the rotation of the rotor 11 of the motor 10 is performed. In addition, excitation fixing control is also performed when the rotor 11 is stopped after rotation. That is, the brushless motor 1 is controlled by switching the rotation control and the excitation fixing control. Here, the excitation fixing control means fixing the rotor 11 at a position specified by an electrical angle, specifically, it means fixing the position of the rotor 11 at a predetermined position by a magnetic field (called excitation) formed by a current flowing through the coil 13 of the stator 12.

[0087] In vector control, excitation fixed control is performed by specifying the electrical angle, setting the q-axis current to "0" A, and setting the d-axis current. Rotation control is performed by setting the q-axis current. In addition, the d-axis current can also be set in rotation control. The q-axis current leads the d-axis current by 90° in phase.

[0088] Here, the control switching unit 320 switches the first switching unit 321, the second switching unit 322, the third switching unit 323, and the fourth switching unit 324 according to the instruction signal obtained by the instruction signal acquisition unit 302, thereby switching the rotation control and the excitation fixing control. Figure 8 In FIG. 1 , the control performed by the control switching unit 320 is indicated by a dotted line, and constants set in the case of field fixing control, here, constants in the case of initial position alignment, are described.

[0089] The timer control unit 301 generates a signal of a certain period and provides it to the instruction signal acquisition unit 302 and the encoder output acquisition unit 304. The instruction signal acquisition unit 302 receives an instruction signal indicating the rotation direction and rotation speed, or the rotation position (the position at which the rotor 11 stops) from other control devices, and the instruction signal acquisition unit 302 receives the instruction signal input from the time when the timer control unit 301 receives a signal to the time when the next signal is received. The other control device mentioned here refers to, for example, a device that controls the operation of the load 2.

[0090] The instruction signal acquisition unit 302 supplies the obtained instruction signal indicating the rotation speed to the target speed setting unit 303, and supplies the obtained instruction signal indicating the position of the rotor 11 to the position control unit 307 via the first switching unit 321. Furthermore, the obtained instruction signal indicating the d-axis current (to be described later) is supplied to the d-axis current control unit 315 via the third switching unit 323. Furthermore, the obtained instruction signal indicating the electrical angle φe is supplied to the coordinate conversion unit 316 via the fourth switching unit 324.

[0091] The target speed setting unit 303 sets the rotation speed indicated by the instruction signal supplied from the instruction signal acquisition unit 302 as a target speed, and supplies the set target speed to the speed control unit 306 .

[0092] The encoder output acquisition unit 304 receives the Figure 5 The encoder output acquisition unit 304 acquires the rotation signal (pulse of phase A and pulse of phase B) output by the encoder 20 shown in FIG. 1 , and acquires the rotation signal input during the period from when the timer control unit 301 is supplied with a signal to when the next signal is supplied, and supplies the acquired rotation signal to the rotation speed calculation unit 305 and the position control unit 307. In addition, the encoder output acquisition unit 304 supplies the acquired rotation signal to the coordinate conversion unit 316 via the fourth switching unit 324. The encoder output acquisition unit 304 is an example of an acquisition unit that acquires the rotation information output by the encoder 20.

[0093] The rotation speed calculation unit 305 calculates the rotation speed of the rotor 11 using the rotation signal provided from the encoder output acquisition unit 304. The rotation speed calculation unit 305 calculates the rotation speed based on, for example, the number of pulses per unit time indicated by the rotation signal. The calculated rotation speed corresponds to the measured value of the current rotation speed of the rotor 11. The rotation speed calculation unit 305 provides the calculated rotation speed to the speed control unit 306.

[0094] The speed control unit 306 performs speed control so that the rotation speed of the rotor 11 provided by the rotation speed calculation unit 305 approaches the target speed set by the target speed setting unit 303. The speed control unit 306 performs speed control using, for example, a PI (Proportional-Integral) control method which is one of feedback controls.

[0095] The speed control unit 306 provides the command value of the q-axis current (a value corresponding to the calculated rotation speed and target speed) among the two-axis currents (d-axis current and q-axis current) obtained by converting the three-phase current flowing through each coil 13 to the q-axis current control unit 314 described later via the second switching unit 322, so that the q-axis current control unit 314 performs control so that the value (iq described later) obtained by converting the measured current flowing through each coil 13 into the q-axis current is close to the command value, thereby making the rotation speed close to the target speed.

[0096] The position control unit 307 uses the position of the rotor 11 indicated by the instruction signal provided via the first switching unit 321 as the target position, and performs position control to bring the position of the rotor 11 closer to the target position using a method such as P (Proportional) control. During the rotation control, the initial position of the rotor 11 is detected. The position control unit 307 detects the current position of the rotor 11 based on the detected initial position and the rotation direction and rotation amount indicated by the rotation signal provided from the encoder output acquisition unit 304.

[0097] The position control unit 307 calculates the error between the rotation position (position at which the rotor 11 is stopped) indicated by the instruction signal provided from the instruction signal acquisition unit 302 via the first switching unit 321 and the detected current position of the rotor 11. The position control unit 307 repeatedly provides the calculated error to the speed control unit 306, and if the error is "0", for example, the speed control unit 306 controls the speed to "0", thereby stopping the rotor 11 at the rotation position.

[0098] The current detection unit 312 obtains Figure 5 The three-phase currents iu, iv, iw respectively flowing through the half-bridge circuits 40u, 40v, 40w of the motor driver unit 311 shown are provided to the current conversion unit 313. Then, the current conversion unit 313 converts the three-phase currents iu, iv, iw into two-phase orthogonal fixed coordinate currents iα, iβ through Clarke transformation. In addition, the current conversion unit 313 obtains the d-axis current id and the q-axis current iq obtained by converting the fixed coordinates of the currents iα, iβ into rotating coordinates through Park transformation. The current conversion unit 313 provides the q-axis current iq obtained in this way to the q-axis current control unit 314 via the second switching unit 322, and provides the d-axis current id to the d-axis current control unit 315 via the third switching unit 323.

[0099] The q-axis current control unit 314 performs control such as PI control to make the q-axis current iq supplied from the current conversion unit 313 close to the command value of the q-axis current supplied from the speed control unit 306. The q-axis current control unit 314 supplies the command value of the q-axis voltage Vq obtained from the q-axis current iq and its command value to the coordinate conversion unit 316. The d-axis current control unit 315 performs control such as PI control to make the d-axis current id supplied from the current conversion unit 313 close to the command value of the d-axis current supplied from another control device via the third switching unit 323. The d-axis current control unit 315 supplies the command value Vd of the d-axis voltage obtained from the d-axis current id and its command value to the coordinate conversion unit 316.

[0100] When the initial position of the rotor 11 is detected, the coordinate conversion unit 316 obtains the current electrical angle based on the rotation direction and rotation amount indicated by the rotation signal provided from the encoder output acquisition unit 304 and the initial position of the rotor 11. The coordinate conversion unit 316 converts the command value of the q-axis voltage provided from the q-axis current control unit 314 and the command value of the d-axis voltage provided from the d-axis current control unit 315 into coordinates of target voltage values ​​(Vu, Vv, Vw) of each phase (U phase, V phase, W phase) by space vector conversion using the obtained electrical angle.

[0101] Then, the PWM conversion unit 317 converts the voltage value coordinates of the three phases into voltage signals serving as PWM signals, and supplies the signals to the motor driver unit 311 .

[0102] Next, the functional unit that performs excitation fixing control in the initial position alignment is described. The following description is made in comparison with the rotation control. As described above, the control switching unit 320 controls the first switching unit 321, the second switching unit 322, the third switching unit 323, and the fourth switching unit 324, and switches the information provided to the downstream functional unit of each switching unit in the case of rotation control and the case of excitation fixing control.

[0103] The control switching unit 320 controls the first switching unit 321. In the case of rotation control, the indication signal indicating the position of the rotor 11 obtained by the indication signal acquisition unit 302 is provided to the downstream position control unit 307. In the case of excitation fixed control in the initial position detection, the position obtained by the indication signal acquisition unit 302 is provided to the downstream position control unit 307 as the target position of the initial position of the rotor 11.

[0104] The control switching unit 320 controls the second switching unit 322. In the case of rotation control, the command value of the q-axis current from the speed control unit 306 and the q-axis current iq from the current conversion unit 313 are provided to the downstream q-axis current control unit 314. In the case of excitation fixed control in the initial position detection, the current value of the q-axis current is set to "0" and the command value of A is provided to the downstream q-axis current control unit 314.

[0105] The control switching unit 320 controls the third switching unit 323. In the case of rotation control, the command value of the d-axis current from other control devices and the d-axis current id from the current conversion unit 313 are provided to the downstream d-axis current control unit 315. In the case of excitation fixed control in the initial position detection, the command value for setting the current value of the d-axis current to a certain value (here "X" A) is provided to the downstream d-axis current control unit 315.

[0106] The control switching unit 320 controls the fourth switching unit 324, and in the case of rotation control, provides the rotation signal from the encoder output acquisition unit 304 to the downstream coordinate conversion unit 316, and in the case of excitation fixed control in the initial position detection, provides the command value that gradually changes the electrical angle to the downstream coordinate conversion unit 316.

[0107] The instruction signal acquisition unit 302 Figure 7 The communication IF 35 in the PWM conversion unit 317, the encoder output acquisition unit 304 and the current detection unit 312 are realized by Figure 7 The input and output IF in the embodiment is realized, and other functional parts except the motor driver part 311 are realized by Figure 7 The control unit is implemented by the CPU 31, ROM 32, and RAM 33. The portion surrounded by the dotted line is an example of the control unit.

[0108] (Initial Position Alignment of the Rotor 11 by Excitation Fixing Control)

[0109] Next, the initial position alignment of the rotor 11 in the first embodiment will be described.

[0110] The encoder 20 of the brushless motor 1 provides a rotation signal (phase A, phase B) to the motor control device 30. The rotation direction and rotation speed of the rotating shaft 14 of the motor 10 are known from the rotation signal (phase A, phase B). However, as described above, when the power is turned on, the position of the rotor 11 in the motor 10 is unknown. Therefore, when the power is turned on, the motor control device 30 makes the position of the rotor 11 consistent with the electrical angle used for control in order to control the rotation of the motor 10. This is the initial position alignment.

[0111] The initial position alignment is performed as follows: Figure 2The coil 13 of the stator 12 shown in the figure provides current to form a magnetic field, so that the rotor 11 stops at a predetermined position. That is, an electrical angle is specified, and a current corresponding to the electrical angle flows through the coil 13, and a magnetic field (excitation) is formed through the stator 12. Then, the rotor 11 is rotated to a position specified by the electrical angle and stopped, thereby making the position of the rotor 11 consistent with the electrical angle used for control. However, when the electrical angle for initial position alignment is specified to be near the zero crossing of the voltage, as shown in FIG. Figure 6 As shown, the current flowing through the coil 13 is prone to error. Therefore, the stop position of the rotor 11 is prone to error. That is, the initial position alignment is deviated. When the initial position alignment is deviated, in the drive of the motor 10, in addition to the error in the position control of the rotor 11, there is a possibility of increased power consumption and fluctuations in the rotation speed.

[0112] Therefore, in the first embodiment, the electrical angle specified for initial alignment is specified avoiding the vicinity of zero crossing, thereby suppressing deviation in initial alignment due to the influence of dead time.

[0113] Fig. 9 It is a diagram for explaining the initial position alignment in the first embodiment. Fig. 9 (a) is the current flowing through each phase of the motor 10, Fig. 9 (b) is the d-axis current, Fig. 9 (c) is the position of the rotor 11. In addition, Fig. 9 In (a), the vertical axis is current (A) and the horizontal axis is electrical angle (°). Fig. 9 In (b), the vertical axis is the d-axis current (A) and the horizontal axis is time. Fig. 9 In (c), the vertical axis is the rotor position (°) and the horizontal axis is time. Fig. 9 On the horizontal axis of (a) and (b), time passes at moments t0, t1, t2, ...

[0114] As described above, the initial position alignment of the rotor 11 based on the excitation fixed control is performed by setting the d-axis current. When performing the initial position alignment, first, the desired electrical angle is specified for the rotor 11 through other control devices. Hereinafter, the electrical angle of the rotor 11 set by other control devices will be described as the command electrical angle. When the motor control device 30 obtains the command electrical angle from other control devices, in order to set the rotor 11 at the position of the command electrical angle, it causes current to flow through the coil 13 of the stator 12. At this time, the command electrical angle is to avoid Fig. 9 The electrical angle to be avoided is the electrical angle of any phase among the U phase, the V phase, and the W phase near the zero crossing.

[0115] exist Fig. 9At the time t0 shown in (b) and (c), as an example, the position of the rotor 11 before the initial position alignment is set to 180°. In addition, the command electrical angle from other control devices to stop the rotor 11 is set to 0°. However, when the power is turned on, the motor control device 30 does not know the position of the rotor 11. In addition, when the command electrical angle is 0°, Fig. 9 As shown in (a), the current of any phase among the U phase, the V phase, and the W phase is not located near the zero crossing. That is, the command electrical angle 0° is an electrical angle that avoids the electrical angle near the zero crossing.

[0116] Furthermore, the motor control device 30 starts to flow a d-axis current for setting the rotation speed of the rotor 11 at time t1. Here, the d-axis current is "X" A. Then, the position of the rotor 11 rotates from 180° to 0° by the magnetic field formed by the d-axis current of "X" A. Then, when the position of the rotor 11 reaches 0° at time t2, the rotor 11 stops rotating and becomes fixed. Then, as shown in FIG. Fig. 9 As shown in (a) of FIG. 1 , at time t3 , the d-axis current is 0. In addition, time t1 < time t2 ≤ time t3. Furthermore, the motor control device 30 calculates the position (0°) of the rotor 11 as the electrical angle (0°) for control.

[0117] Even when the rotor 11 has 4 poles, 6 poles, 8 poles, etc. instead of 2 poles, or when the number of coils 13 of the stator 12 is 6, 9, 12, etc. instead of 3, the position of the rotor 11 is fixed (excitation fixed) at a position corresponding to the command electrical angle.

[0118] In the initial position alignment described above, whether the rotor 11 has been fixed at the position 0° can be determined based on the elapse of a predetermined time (here t2-t1) from the moment t1 when the d-axis current starts to flow, or by detecting the cessation of rotation based on the rotation amount of the rotor 11 output by the encoder 20.

[0119] Furthermore, after the initial position alignment of the rotor 11 is completed, the rotor 11 may be rotated in the reverse direction according to the rotation amount of the rotor 11 during the initial position alignment (the time from time t1 to time t2) obtained by the motor control device 30 from the encoder 20, so that the rotor 11 returns to the position when the power is turned on (before the initial position alignment is performed). In this case, the electrical angle of the position of the rotor 11 when the power is turned on (before the initial position alignment is performed) is calculated based on the command electrical angle and the rotation amount of the rotor 11.

[0120] As described above, in the first embodiment, the command electrical angle is set to avoid the electrical angle at which the current of any of the U-phase, V-phase, and W-phase is near zero crossing. Fig. 9As can be seen from (a), the electrical angles of 30°, 90°, 150°, 210°, 270°, and 330° in the d-axis current are the electrical angles at which the current of any phase among the U phase, the V phase, and the W phase passes through zero. Therefore, the command electrical angle can be set by avoiding the electrical angles near these angles.

[0121] In addition, the vicinity of zero crossing refers to a range smaller than ±10°, for example, with respect to the electrical angle of zero crossing.

[0122] [Second embodiment]

[0123] In the first embodiment, the command electrical angle is set to avoid the electrical angle that makes any current in the U phase, V phase, and W phase near zero crossing, and the initial position alignment is performed. In the second embodiment, the command electrical angle is set to the electrical angle that makes the absolute value of any current in the U phase, V phase, and W phase maximum, and the initial position alignment is performed (refer to the following description). Fig.10 The other structures are the same as those in the first embodiment, and thus the description thereof is omitted.

[0124] like Fig. 9 As shown in (a), for the electrical angle that makes the absolute value of any current in the U phase, V phase, and W phase the maximum, the U phase current is the maximum on the negative side at 0°, the W phase current is the maximum on the positive side at 60°, the V phase current is the maximum on the negative side at 120°, the U phase current is the maximum on the positive side at 180°, the W phase current is the maximum on the negative side at 240°, and the V phase current is the maximum on the positive side at 300°. If it is this electrical angle, the current of the phase other than the phase with the largest absolute value is not near zero crossing.

[0125] [Third Embodiment]

[0126] In the second embodiment, the command electrical angle is set and the excitation of the rotor 11 is fixed to the electrical angle. In the third embodiment, the rotation amount of the rotor 11 during the initial position alignment is reduced. The other configurations are the same as those of the first embodiment, and thus description thereof is omitted.

[0127] Fig.10 It is a diagram for explaining the initial position alignment in the third embodiment. Fig.10 (a) is the current flowing through each phase of the motor 10, Fig.10 (b) is the d-axis current, Fig.10 (c) is the position of the rotor 11. In addition, Fig.10 In (a), the vertical axis is current (A) and the horizontal axis is electrical angle (°). Fig.10 In (b), the vertical axis is the d-axis current (A) and the horizontal axis is time. Fig.10 In (c), the vertical axis is the rotor position (°) and the horizontal axis is time. Fig.10 The time t0, t1, t2, ... assigned to the horizontal axis of (b) and (c) is Fig. 9 The times t0, t1, t2, ... assigned to the horizontal axes of (b) and (c) are different.

[0128] Here, the position of the rotor 11 before the initial position alignment (at time t0) is set to 140°. Also, the command electrical angle is set to 0°. Fig.10 As shown in (a), the command electrical angle of 0° is the electrical angle that makes the U-phase current maximum on the negative side (absolute value).

[0129] Then, the motor control device 30 starts to flow a d-axis current for setting the rotation speed of the rotor 11 at time t1. Here, the d-axis current is "X" A. Then, the rotor 11 starts to rotate toward the position 0°. In this case, the rotor 11 needs to rotate 140°. Here, Fig.10 The electrical angle shown in (a) is the same as the position of the rotor 11. Therefore, according to Fig.10 As can be seen from (a), in the direction from position 140° toward position 0°, the electrical angle 120° where the absolute value of the V-phase current is the largest is closest to position 140°. However, when the power is turned on, the motor control device 30 does not know the position of the rotor 11, so the rotor 11 is gradually rotated toward the command electrical angle 0°.

[0130] When the motor control device 30 detects that the rotation amount of the rotor 11 is more than 60° based on the rotation information from the encoder 20, the command electrical angle 0° plus 60° is reset to 60° as a new command electrical angle. At this time, the position of the rotor 11 is 80°. However, the command electrical angle 60° is on the same side as the previous command electrical angle 0°. Therefore, the rotor 11 rotates in the same direction as before, toward the command electrical angle 60°. Therefore, when the motor control device 30 detects that the rotor 11 rotates in the same direction even if the command electrical angle is reset based on the rotation information from the encoder 20, the command electrical angle 120° obtained by further adding 60° to the command electrical angle 60° is reset to a new command electrical angle. At this time, the position of the rotor 11 moves to the side further less than 80°. Therefore, the command electrical angle 120° is in the direction of reverse rotation from the position of the rotor 11. Therefore, the rotor 11 starts to rotate in the opposite direction to before, toward the command electrical angle 120°. And, it is excited and fixed at the position of the command electrical angle 120°. That is, the initial position alignment is performed at a position (in this example, 120°) closest to the position when the power is turned on (before the initial position alignment) of the rotor 11 (in this example, 140°). Furthermore, the motor control device 30 calculates the position of the rotor 11 as an electrical angle for control.

[0131] That is, in the case of three phases, Fig.10 As shown in (a), the electrical angle at which the absolute value of each phase current is maximized is 60° intervals. Therefore, when the rotor 11 is rotated toward the command electrical angle, when the rotor 11 rotates more than 60°, the initial position alignment of the rotor 11 is performed by crossing the closest electrical angle at which the absolute value of the current is maximized. Therefore, when the rotor 11 rotates more than 60°, the motor control device 30 reduces the command electrical angle by 60° based on the rotation information from the encoder 20. In addition, it is determined whether the rotation direction of the rotor 11 is reversed. When the rotation direction of the rotor 11 is the same, that is, when the rotation direction is not reversed, the command electrical angle is further reduced by 60°. On the other hand, when the rotation direction is reversed, the command electrical angle is maintained and the position of the rotor 11 is fixed to the command electrical angle. In this case, the rotor 11 is fixed to the electrical angle that is closest to the initial position of the rotor 11 and that makes the absolute value of the current the largest. In addition, when the power is turned on, the encoder 20 does not grasp the position of the rotor 11 when the power is turned on, but detects the rotation speed and rotation direction of the rotor 11.

[0132] This prevents the load 2 connected to the rotor 11 from being in a state significantly deviated from the state before the position alignment.

[0133] In addition, the above is the case where the command electrical angle is smaller than the position of the rotor 11 when the power is turned on (before the initial position alignment). On the contrary, when the command electrical angle is larger than the position of the rotor 11 when the power is turned on (before the initial position alignment), the rotation direction is reversed.

[0134] The above 60° refers to a case where the rotor 11 has one set of magnetic poles, the stator 12 has three poles, and the motor 10 is driven by three phases. In the case of other structures, the value may be set according to the structure. 60° is an example of a predetermined amount in the rotation amount of the rotation information.

[0135] [Fourth embodiment]

[0136] In the first to third embodiments, in the initial position alignment of the rotor 11 based on the excitation fixing control, the influence of the dead time for preventing the high-side switching element (p-channel FET 41) and the low-side switching element (n-channel FET 42) from being turned on at the same time is suppressed. Figure 8 A dead time correction unit 318 is provided between the coordinate conversion unit 316 and the PWM conversion unit 317 to correct the voltage waveform (Vu, Vv, Vw) of each phase output by the coordinate conversion unit 316 and provide it to the PWM conversion unit 317, thereby suppressing the influence of the dead time in the rotation control and the excitation fixing control.

[0137] Fig.11FIG. 4 is a diagram showing an example of a functional configuration of a motor control device 30A to which the fourth embodiment is applied. Figure 8 In addition to the configuration of the motor control device 30 according to the first embodiment, the motor control device 30A includes a dead time correction unit 318 between the coordinate conversion unit 316 and the PWM conversion unit 317. The other configurations are the same as those of the first embodiment, and thus description thereof is omitted.

[0138] Dead time correction unit 318 corrects voltages Vu, Vv, Vw supplied from coordinate conversion unit 316 and supplies them as voltages Vu′, Vv′, Vw′ to PWM conversion unit 317. Dead time correction unit 318 is supplied with a signal related to electrical angle φe supplied to coordinate conversion unit 316.

[0139] Fig.12 3 is a diagram showing the waveform of the target voltage provided by the coordinate conversion unit 316 and the waveform of the correction voltage after correction by the dead time correction unit 318 . Fig.12 (a) is the waveform of the target voltage (Vu, Vv, Vw) provided by the coordinate conversion unit 316, Fig.12 (b) is the waveform of the correction voltage (Vu′, Vv′, Vw′) after the dead time correction unit 318 corrects the voltage. Fig.12 In (a) and (b), the vertical axis is voltage (V) and the horizontal axis is electrical angle (°). Fig.12 In (a) and (b), one phase out of three phases is shown.

[0140] Fig.12 The waveforms (Vu′, Vv′, Vw′) of the correction voltages after correction by the dead time correction unit 318 shown in (b) are Fig.12 The waveform of the target voltage (Vu, Vv, Vw) shown in (a) is a waveform separated by a voltage of 0 V and shifted to the + side and the - side. As a result, the absolute value of the voltage near the zero crossing is particularly large. As a result, the influence of the dead time is suppressed.

[0141] Fig.13 The diagram shows an example of the relationship between the correction voltage (Vu′, Vv′, Vw′) set for each phase of the motor 10 , the current flowing through each phase of the motor 10 , and the rotation amount of the rotating shaft 14 of the motor 10 . Fig.13 (a) is a correction voltage (Vu′, Vv′, Vw′) set for each phase (U phase, V phase, W phase) of the motor 10, Fig.13 (b) is the current flowing through each phase (U phase, V phase, W phase) of the motor 10, Fig.13 (c) is the rotation amount of the rotating shaft 14 of the motor 10. Here, the horizontal axis is time. In addition, Fig.13The dashed line in (c) shows an ideal case where the rotation amount of the rotating shaft 14 of the motor 10 changes in proportion to time.

[0142] like Fig.12 As shown in (b), Fig.13 The correction voltage set for each phase (U phase, V phase, W phase) of the motor 10 shown in (a) is near zero crossing, and the voltage is offset to the + side and the - side. Figure 6 Compared with the voltage waveform shown in (a) when no dead time correction is performed, the voltage waveform near zero crossing is different. Fig.13 The current flowing through each phase (U phase, V phase, W phase) of the motor 10 relative to the target voltage shown in (b) is approximately a sine wave. Fig.13 In (b), the inhibition Figure 6 The deviations of the α portion where the voltage Vw intersects 0 V, the β portion where the voltage Vu intersects 0 V, and the γ portion where the voltage Vv intersects 0 V from the sine wave in (a).

[0143] Therefore, if Fig.13 As shown in (c), the rotation amount of the rotating shaft 14 is suppressed from deviating from the rotation amount of the ideal rotating shaft 14 shown by the dot-dash line. That is, the dead time correction unit 318 is provided to correct the target voltages Vu, Vv, and Vw provided by the coordinate conversion unit 316 to the correction voltages Vu′, Vv′, and Vw′, thereby suppressing the possibility of an error in the position control of the rotor 11 due to the dead time, or an increase in power consumption or a change in the rotation speed of the rotor 11 due to the rotor 11 not being in a predetermined position.

[0144] Fig.14 This is a diagram showing a timing diagram of controlling the rotation of the motor 10 by applying the motor control device 30A of the fourth embodiment. The horizontal axis is time, and it is assumed that time passes in the order of time a, b, c, ... Here, it is assumed that the initial position alignment of the rotor 11 based on the excitation fixed control described in the first embodiment is completed, and at time a, the start of rotation of the motor 10 (motor ON) is instructed by other control devices. Fig.14 In the figure, from the top, there are recorded the command speed indicating the rotation speed of the rotor 11 from other control devices, the motor ON signal indicating the start of rotation of the motor 10, the position error of the rotor 11, the motor stop (STOP) signal indicating the stop of the motor 10, the target q-axis current, the target d-axis current and the electrical angle φe of the motor 10.

[0145] The motor 10 is controlled to rotate by a motor ON signal indicated by another control device. On the other hand, the motor 10 is stopped by an instruction from another control device to set the command speed to "0". At this time, the speed control unit 306 provides a motor STOP signal to the coordinate conversion unit 316. That is, the motor 10 is stopped by an excitation control in which the command speed is set to "0", the q-axis current is set to "0" A, and the d-axis current is set to "X" A. In addition, the command speed of "0" is an example of a command signal for stopping, and setting the command speed to "0" by another control device is an example of receiving a command speed for stopping.

[0146] When the rotation of the motor 10 is indicated by the motor ON signal at time a, the command speed is set to gradually increase from "0". Immediately after time a, the position error of the rotor 11 immediately becomes under-rotation, which is rotating slower than the command speed. As the rotor 11 rotates, the position error decreases. At this time, by setting the target q-axis current to be larger, the rotation speed is controlled to increase and the command speed is easily reached. Therefore, when approaching time b when the command speed is set to a constant value, it becomes over-rotation, which is rotating faster than the command speed. In addition, the target d-axis current is set to "0" A.

[0147] When the command speed is set to a constant value at time b, control is performed so as to reduce the target q-axis current so that the overspeed can easily reach the command speed.

[0148] At time c, the position error is "0", and the rotor 11 rotates at the command speed. In addition, the target q-axis current is maintained at a constant value so that the rotor 11 keeps rotating at the command speed.

[0149] At time d, the command speed is set to gradually decrease toward the stopped state starting from time e. As a result, the position error of the rotor 11 becomes under-rotation again after temporarily becoming over-rotation. At this time, in order to suppress over-rotation, the target q-axis current is set to the + side again after temporarily being set to the - side.

[0150] When the command speed is "0" at time e, the target q-axis current is set to "0" A, and the target d-axis current becomes a preset value. That is, excitation fixing control is performed. Here, the position error of the rotor 11 is stopped from the under-rotation state and fixed at a preset electrical angle φe.

[0151] When the command speed is set to gradually increase again at time f, the rotation of the rotor 11 starts in the same manner as at time a. The process from time f to time k is the same as the process from time a to time k, and thus the description thereof will be omitted.

[0152] As described above, the rotation of the rotor 11 is controlled by the command speed. Here, as shown from time a to time b, the target q-axis current is adjusted according to the position error of the rotor 11, so that the rotation speed of the rotor 11 is quickly controlled to converge to the command speed. In addition, although the time for the rotation speed of the rotor 11 to converge to the command speed becomes longer, the target q-axis current can also be set to a constant value.

[0153] [Fifth embodiment]

[0154] In the fourth embodiment, the dead time correction unit 318 always corrects the target voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to the correction voltage (Vu′, Vv′, Vw′) and supplies it to the PWM conversion unit 317. In the fifth embodiment, the dead time correction unit 318 corrects the target voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to the correction voltage (Vu′, Vv′, Vw′) and supplies it to the PWM conversion unit 317 only when the motor STOP signal is supplied.

[0155] Fig.15 FIG. 2 is a diagram showing an example of a functional configuration of a motor control device 30B to which the fifth embodiment is applied. Fig.11 In addition to the configuration of the motor control device 30A according to the fourth embodiment, the motor control device 30B provides a motor STOP signal from the speed control unit 306 to the dead time correction unit 318. The other configurations are the same as those of the fourth embodiment, and thus description thereof is omitted.

[0156] Thus, in the case of rotation control, the dead time correction unit 318 does not perform voltage correction, but provides the target voltage (Vu, Vv, Vw) provided by the coordinate conversion unit 316 to the PWM conversion unit 317. Furthermore, when the motor STOP signal is provided from the speed control unit 306, the target voltage (Vu, Vv, Vw) provided by the coordinate conversion unit 316 is corrected to the correction voltage (Vu', Vv', Vw') and provided to the PWM conversion unit 317. Thus, the load of the CPU 31 in the motor control device 30 is reduced. That is, when the dead time correction is performed regardless of the presence or absence of the motor STOP signal, the correction voltage (Vu', Vv', Vw') is generated following the time change of the target voltage (Vu, Vv, Vw). However, when the motor 10 to which the motor STOP signal is provided is stopped, the target voltage (Vu, Vv, Vw) is fixed, so it is easy to correct it to the correction voltage (Vu', Vv', Vw'). That is, the dead time correction can be performed without using an expensive CPU 31 that operates at high speed.

[0157] [Sixth embodiment]

[0158] In the fifth embodiment, only when the motor STOP signal is provided, the dead time correction unit 318 corrects the target voltage (Vu, Vv, Vw) provided from the coordinate conversion unit 316 to the correction voltage (Vu′, Vv′, Vw′) and provides it to the PWM conversion unit 317. In the sixth embodiment, only when the rotation speed of the motor 10 is less than a predetermined speed, the dead time correction unit 318 corrects the voltage (Vu, Vv, Vw) provided from the coordinate conversion unit 316 to the voltage (Vu′, Vv′, Vw′) and provides it to the PWM conversion unit 317.

[0159] Fig.16 FIG. 2 is a diagram showing an example of a functional configuration of a motor control device 30C to which the sixth embodiment is applied. Fig.15 In addition to the structure of the motor control device 30B to which the fifth embodiment is applied, the motor control device 30C includes a rotation speed determination unit 308. The rotation speed determination unit 308 supplies a rotation speed signal indicating that the rotation speed (here, R) of the rotor 11 supplied from the rotation speed calculation unit 305 is less than a predetermined rotation speed (here, Rth) (R≤Rth) to the dead time correction unit 318. The dead time correction unit 318 corrects the target voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to a correction voltage (Vu′, Vv′, Vw′) and supplies the correction voltage to the PWM conversion unit 317 only when the rotation speed signal is supplied. In addition, the rotation speed signal may be supplied when the rotation speed (R) of the rotor 11 is less than the predetermined rotation speed (Rth) (R<Rth).

[0160] Thus, when the rotation speed (R) of the rotor 11 exceeds the predetermined rotation speed (Rth), the dead time correction unit 318 does not correct the voltage, but provides the target voltage (Vu, Vv, Vw) provided from the coordinate conversion unit 316 to the PWM conversion unit 317. Furthermore, when the rotation speed (R) of the rotor 11 is less than or lower than the predetermined rotation speed (Rth), the target voltage (Vu, Vv, Vw) provided from the coordinate conversion unit 316 is corrected to the correction voltage (Vu′, Vv′, Vw′) and provided to the PWM conversion unit 317. Thus, the load of the CPU 31 in the motor control device 30C is reduced. That is, when the rotation speed is low, the time change of the target voltage (Vu, Vv, Vw) is slow compared to when the rotation speed is high. Therefore, if the time change of the target voltage (Vu, Vv, Vw) is slow, it is easy to correct it to the correction voltage (Vu′, Vv′, Vw′). That is, even if an expensive CPU operating at high speed is not used as the CPU 31, dead time correction can be performed.

[0161] [Seventh embodiment]

[0162] In the fourth embodiment, the rotor 11 is fixed at a position of a preset electrical angle φe in a stopped state. However, due to the influence of the load 2, etc., the stopped position may be different from the set electrical angle φe. In the seventh embodiment, when the stopped position of the rotor 11 is different from the electrical angle φe, the electrical angle is corrected.

[0163] Fig.17 FIG. 2 is a diagram showing an example of a functional configuration of a motor control device 30D to which the seventh embodiment is applied. Fig.11 In addition to the structure of the motor control device 30A according to the fourth embodiment, the motor control device 30D includes a correction electrical angle calculation unit 309. When there is a deviation (set to Δφe) in the stop position of the rotor 11 obtained from the encoder output acquisition unit 304, the correction electrical angle calculation unit 309 corrects the deviation (Δφe) of the electrical angle by (-Δφe) and provides the correction electrical angle φe′ to the dead time correction unit 318. Then, the dead time correction unit 318 replaces the electrical angle with the correction electrical angle φe′.

[0164] Fig.18 1 is a diagram showing a timing chart of controlling the rotation of the motor 10 by applying the motor control device 30D according to the seventh embodiment. The horizontal axis represents time. Fig.18 The timing diagram of Fig.14 Therefore, the description is given between time e and time f, and the description of other parts is omitted. Here, time e1 is set between time e and time f.

[0165] When the command speed becomes "0" at time e, the rotor 11 is transferred to a stopped state. Therefore, it is assumed that the position where the rotor 11 stops deviates from the specified position by an electrical angle Δφe. That is, the electrical angle of the stop position has an error of Δφe. Therefore, the corrected electrical angle calculation unit 309 calculates the electrical angle φe' after the electrical angle φe is corrected by -Δφe, and provides it to the dead time correction unit 318. As a result, the electrical angle φe is corrected to the electrical angle φe', thereby suppressing the influence on the subsequent rotation control of the rotor 11. In addition, when the rotation control from time f is performed in a state where there is an error in the stop position, the control is performed in a state where the position of the rotor 11 still has an error.

[0166] [Eighth embodiment]

[0167] In the fifth to seventh embodiments, the d-axis current continues to flow when the rotor 11 is stopped. However, if the rotor 11 is kept stopped, the d-axis current does not need to continue to flow. In the eighth embodiment, the d-axis current is reduced after the rotor 11 is stopped.

[0168] Fig.19 FIG. 2 is a diagram showing an example of the functional configuration of a motor control device 30E to which the eighth embodiment is applied. Fig.11 Based on the structure of the motor control device 30A of the fourth embodiment shown in the figure, the motor control device 30E has a d-axis current adjustment unit 310. The d-axis current adjustment unit 310 is supplied with the d-axis current via the third switching unit 323, and is supplied with the electrical angle φe via the fourth switching unit 324. Therefore, when the position of the rotor 11 in the stopped state is at the position specified by the electrical angle φe, the reduced d-axis current is supplied to the dead time correction unit 318. The case where the position of the rotor 11 is at the position specified by the electrical angle φe includes the case where the position error is less than a predetermined range or less than a predetermined range.

[0169] Fig. 20 1 is a diagram showing a timing chart of controlling the rotation of the motor 10 by applying the motor control device 30E according to the eighth embodiment. The horizontal axis represents time. Fig. 20 The timing diagram of Fig.14 Therefore, the time between time e and time f and time j and time k will be described, and the description of other parts will be omitted. Here, time e1, e2, e3, and e4 are set between time e and time f, and time j1 and j2 are set between time j and time k.

[0170] When the command speed becomes "0" at time e, the rotor 11 is transferred to a stopped state. At time e1, there is a position error in the rotor 11, so the d-axis current adjustment unit 310 maintains the d-axis current that causes the rotor 11 to be transferred to a stopped state. At time e2, when the position error becomes below a predetermined range or is less than a predetermined range, the d-axis current adjustment unit 310 gradually decreases (reduces) the d-axis current. However, at time e3, when the position error exceeds a predetermined range or becomes above a predetermined range, the d-axis current adjustment unit 310 gradually increases (increases) the d-axis current. As a result, the position error decreases. Then, at time e4, the d-axis current adjustment unit 310 maintains the d-axis current at this time.

[0171] Similarly, when the command speed becomes "0" at time j, the rotor 11 also shifts to the stopped state. At time j1, when the position error of the rotor 11 becomes less than or smaller than a predetermined range, the d-axis current adjustment unit 310 gradually decreases (reduces) the d-axis current. At this time, no position error occurs at time j2, so the d-axis current adjustment unit 310 sets the d-axis current to "0"A.

[0172] As described above, the d-axis current adjustment unit 310 changes the d-axis current according to the position error (deviation of the electrical angle φe) of the rotor 11 when the rotor 11 is transferred to the stopped state. For example, if the position error of the rotor 11 is below or below a predetermined range, the d-axis current adjustment unit 310 may set the d-axis current to "0" A. In addition, if the position error of the rotor 11 exceeds a predetermined range or becomes above a predetermined range in the stopped state, the d-axis current may be increased to reduce the position error of the rotor 11. Furthermore, if the position error of the rotor 11 is below or below a predetermined range, the d-axis current may be further reduced from the d-axis current when the rotor 11 is transferred to the stopped state. In this way, the current consumption of the motor control device 30 is suppressed. In addition, the predetermined range of the position error does not necessarily have to be "0" but refers to an allowable error range.

[0173] Some of the fifth to eighth embodiments described above may be used in combination.

Claims

1. A control device, wherein: The control device includes a control unit, and the control unit controls the voltage and current applied to each of the plurality of phases of the brushless motor by vector control. The vector control is performed by rotation control mainly using q-axis current when controlling the rotation of the rotor, and is performed by excitation fixing control mainly using d-axis current when receiving a stop command signal. The control unit controls the brushless motor by suppressing the influence of the dead time when both the high-side switching elements and the low-side switching elements constituting the plurality of half-bridge circuits are set to be disconnected during the excitation fixed control, wherein the plurality of half-bridge circuits are provided corresponding to each of the plurality of phases of the brushless motor and provide voltage and current to each phase. The control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor. The control unit sets an electrical angle at which a voltage applied to any phase of the plurality of phases of the brushless motor becomes a voltage with a maximum absolute value when aligning the position of the rotor of the brushless motor with an initial position of the electrical angle in the vector control in the excitation fixing control, and calculates an electrical angle corresponding to the position of the rotor based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor. When the rotor rotates according to the set electrical angle, and the rotation amount of the rotation information obtained from the acquisition unit becomes greater than a predetermined amount, the control unit resets the electrical angle that is closest to the direction opposite to the rotation direction of the rotor and makes the voltage of any phase among the multiple phases become the electrical angle with the largest absolute value to perform initial position alignment.

2. The control device according to claim 1, wherein: When the control unit aligns the position of the rotor of the brushless motor with the initial position of the electrical angle in the vector control during the excitation fixing control, the control unit sets the following electrical angle: the electrical angle avoids the electrical angle at which the voltage applied to any phase of the multiple phases of the brushless motor becomes a voltage near zero crossing, and calculates the electrical angle corresponding to the position of the rotor based on the rotation information obtained by the acquisition unit, thereby controlling the brushless motor.

3. The control device according to claim 1 or 2, wherein: After the initial position alignment is completed, the control unit returns the position of the rotor to the position before the initial position alignment.

4. The control device according to claim 1, wherein: The control unit sets a voltage applied to each of the plurality of phases of the brushless motor as a voltage obtained by correcting a voltage in the rotation control during the field fixing control.

5. The control device according to claim 4, wherein: When the rotor is stopped, if there is a deviation between the position of the rotor obtained based on the rotation information acquired by the acquisition unit and the commanded electrical angle, the control unit corrects the electrical angle according to the deviation.

6. The control device according to claim 5, wherein: When the rotor stops by the excitation fixing control, the control unit reduces the d-axis current if the deviation between the position of the rotor obtained according to the rotation information obtained by the acquisition unit and the commanded electrical angle is below or less than a predetermined range; and increases the d-axis current if the deviation between the position of the rotor and the commanded electrical angle exceeds a predetermined range.

7. The control device according to claim 4, wherein: When the rotor stops by the excitation fixing control, the control unit reduces the d-axis current if the deviation between the position of the rotor obtained according to the rotation information obtained by the acquisition unit and the commanded electrical angle is below or less than a predetermined range; and increases the d-axis current if the deviation between the position of the rotor and the commanded electrical angle exceeds a predetermined range.

8. A control device, wherein: The control device includes a control unit, and the control unit controls the voltage and current applied to each of the plurality of phases of the brushless motor by vector control. The vector control is performed by rotation control mainly using q-axis current when controlling the rotation of the rotor, and is performed by excitation fixing control mainly using d-axis current when receiving a stop command signal. The control unit controls the brushless motor by correcting the target voltage of the voltage applied to each of the plurality of phases of the brushless motor, suppressing the influence of the dead time when both the high-side switching elements and the low-side switching elements constituting the plurality of half-bridge circuits are set to be turned off, and the plurality of half-bridge circuits provide voltage and current to the respective phases, The control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor. The control unit sets an electrical angle at which a voltage applied to any phase of the plurality of phases of the brushless motor becomes a voltage with a maximum absolute value when aligning the position of the rotor of the brushless motor with an initial position of the electrical angle in the vector control in the excitation fixing control, and calculates an electrical angle corresponding to the position of the rotor based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor. When the rotor rotates according to the set electrical angle, and the rotation amount of the rotation information obtained from the acquisition unit becomes greater than a predetermined amount, the control unit resets the electrical angle that is closest to the direction opposite to the rotation direction of the rotor and makes the voltage of any phase among the multiple phases become the electrical angle with the largest absolute value to perform initial position alignment.

9. A control device comprising: an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of a rotor of the brushless motor; and a control unit that controls the voltage and current applied to each of the plurality of phases of the brushless motor by vector control, wherein the vector control is performed by rotation control mainly using the q-axis current when controlling the rotation of the rotor, and is performed by excitation fixing control mainly using the d-axis current when receiving a stop command signal, The control unit controls the brushless motor by correcting the voltage applied to each of the plurality of phases of the brushless motor to a target voltage when the rotation speed of the rotor obtained based on the rotation information obtained by the acquisition unit is equal to or less than a predetermined rotation speed. The control unit sets an electrical angle at which a voltage applied to any phase of the plurality of phases of the brushless motor becomes a voltage with a maximum absolute value when aligning the position of the rotor of the brushless motor with an initial position of the electrical angle in the vector control in the excitation fixing control, and calculates an electrical angle corresponding to the position of the rotor based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor. When the rotor rotates according to the set electrical angle, and the rotation amount of the rotation information obtained from the acquisition unit becomes greater than a predetermined amount, the control unit resets the electrical angle that is closest to the direction opposite to the rotation direction of the rotor and makes the voltage of any phase among the multiple phases become the electrical angle with the largest absolute value to perform initial position alignment.

10. A brushless motor, comprising: The control device according to any one of claims 1 to 9; a rotor; and A plurality of coils are arranged around the rotor in correspondence with a plurality of voltages and currents to which the voltages and currents controlled by the control device are applied.

11. A control method, wherein: The voltage and current of each phase of the brushless motor are controlled by vector control. When the rotation of the rotor is controlled, the vector control is performed by rotation control mainly based on the q-axis current, and when a stop command signal is received, the excitation fixing control is performed mainly based on the d-axis current. In the excitation fixed control, the brushless motor is controlled by suppressing the influence of the dead time when the high-side switching elements and the low-side switching elements constituting the plurality of half-bridge circuits are both set to be disconnected, wherein the plurality of half-bridge circuits are provided corresponding to each of the plurality of phases of the brushless motor and provide voltage and current to each phase. obtaining rotation information indicating the rotation amount and rotation direction of the rotor of the brushless motor, In the excitation fixed control, when the position of the rotor of the brushless motor is aligned with the initial position of the electrical angle in the vector control, the electrical angle at which the voltage applied to any phase of the plurality of phases of the brushless motor becomes the voltage with the largest absolute value is set, and the electrical angle corresponding to the position of the rotor is calculated based on the rotation information obtained, thereby controlling the brushless motor. When the rotor rotates according to the set electrical angle and the rotation amount of the rotation information obtained becomes greater than a predetermined amount, the electrical angle closest to the direction opposite to the rotation direction of the rotor is reset to make the voltage of any phase among the multiple phases have the largest absolute value, and the initial position alignment is performed.

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