JP5441624B2 - Motor drive device - Google Patents

Description

  The present invention relates to a motor drive device, and more particularly to a motor drive device having a position sensor for detecting the position of a rotor.

In motor drive devices that perform motor drive control by switching between open-loop drive and feedback drive, switching from feedback drive to open-loop drive is usually performed when the rotational speed of the rotor detected based on the position sensor reaches a predetermined value. When done.
Patent Document 1 discloses that switching between open-loop driving and feedback driving is performed at a timing according to the output of a motor position sensor. Also disclosed is a method for preventing vibration of the rotor at the time of switching by matching the rotational position of the rotor at the time of switching with the position where the rotor is electromagnetically stable and stationary in microstep drive.

JP-A-10-150798

  However, if the rotational acceleration of the rotor is large (the rotational speed change is large) when switching from feedback driving to open loop driving, the rotational frequency at the time of switching and the driving frequency of the open loop driving cannot be matched, and the motor step out May cause.

  Further, the technique disclosed in Patent Document 1 is effective for switching after the motor is sufficiently decelerated, but when the motor is rotating, the position where the rotor is electromagnetically stable and stationary. It is desirable to switch at a slightly shifted position. This is because in the case of open-loop driving, the rotor rotates with a lag with respect to the drive voltage application timing as the rotation speed increases. When the technique of Patent Document 1 is executed while the motor is rotating, there is a possibility that vibration is caused.

  Therefore, the present invention provides a motor drive device that suppresses the occurrence of step-out and vibration.

  A motor driving device according to one aspect of the present invention includes: a first driving unit that performs open-loop driving of the motor by switching energization to a coil of the motor according to a predetermined time interval; and a position sensor that detects a position of the rotor. A second driving unit that feedback-drives the motor by switching energization of the coil of the motor according to an output; an arithmetic unit that calculates a speed and an acceleration of the rotor from an output of the position sensor; Control means for controlling the drive of the motor by switching between one drive means and the second drive means, and the control means performs acceleration, constant speed, and deceleration drive of the rotor by the second drive means, When switching from the feedback drive to the open loop drive, the speed of the rotor is the rotor during the open loop drive. A maximum speed following speed, and so that a constant speed, drives and controls the motor in the second drive means.

  Other objects and features of the present invention are illustrated in the following examples.

  ADVANTAGE OF THE INVENTION According to this invention, the motor drive device which suppresses generation | occurrence | production of a step-out and a vibration can be provided.

It is an external appearance perspective view of the motor in a present Example. It is a block block diagram of the motor drive device in a present Example. In the motor of a present Example, it is sectional drawing of the axial direction which shows the phase relationship of a yoke, a position sensor, and a rotor. In a present Example, it is a graph which shows the relationship between a rotor position and a motor torque, and the relationship between a rotor position and the output of a position sensor. It is a block diagram of the advance angle circuit in a present Example. In the motor of a present Example, it is sectional drawing of the axial direction which shows the operation | movement at the time of FB drive. In this embodiment, when the advance angle signal has a predetermined advance angle α, the relationship between the rotation angle of the rotor and the motor torque and the relationship between the rotation angle of the rotor and the output of each signal are shown. In a present Example, it is a graph which shows the relationship between a torque when changing an advance angle, and rotation speed. It is a figure which shows the mode (from a drive start to a drive end) of the drive of the motor drive apparatus in a present Example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted.

  First, the configuration of a motor driven by the motor drive device of this embodiment will be described. FIG. 1 is an external perspective view of a motor 101 of this embodiment. In FIG. 1, some parts are shown broken for illustration. The motor 101 includes a rotor 202 having a magnet 201, a first coil 203, a second coil 204, a first yoke 205, a second yoke 206, a first position sensor 207, and a second position sensor 208. Is provided. Among these, the first coil 203, the second coil 204, the first yoke 205, the second yoke 206, the first position sensor 207, and the second position sensor 208 constitute a stator.

  The magnet 201 is a cylindrical permanent magnet whose outer periphery is multipolarly magnetized. It has a magnetization pattern in which the strength of the magnetic force in the radial direction changes in a sinusoidal shape with respect to the angular position. As the magnet 201, for example, a neodymium magnet having a high magnetic flux density is used, but is not limited thereto. The rotor 202 is rotatably supported with respect to the stator and is fixed integrally with the magnet 201.

  The first yoke 205 has a plurality of magnetic pole teeth that are excited by the first coil 203. The torque applied to the rotor 202 can be changed by switching the poles to be excited. The second yoke 206 has a plurality of magnetic pole teeth that are excited by the second coil 204. The torque applied to the rotor 202 can be changed by switching the poles to be excited.

  The first position sensor 207 and the second position sensor 208 are Hall elements that detect the magnetic flux of the magnet 201 and output a detection signal thereof. In this embodiment, the magnetic flux of the magnet 201 is detected by a Hall element. However, the rotor position detection method is not limited to this. Detection may be performed by arranging a detection magnet that is displaced with the rotation of the rotor, and the light shielding plate and the pattern surface may be read by an optical sensor. The position sensor may be fixed integrally with the motor, or may be fixed to a member different from the motor.

  Next, the configuration of the motor driving device in the present embodiment will be described. FIG. 2 is a block configuration diagram of the motor drive device 1. A position sensor signal processing circuit 301 processes the outputs of the first position sensor 207 and the second position sensor 208 included in the motor 101. Reference numeral 302 denotes a control unit that selects either a feedback drive circuit 303 or an open loop drive circuit 304, which will be described later, and performs drive control such as acceleration, constant speed, and deceleration drive (stop drive). Reference numeral 303 is a feedback drive circuit, and 304 is an open loop drive circuit. One of the feedback drive circuit 303 and the open loop drive circuit 304 selected by the control unit 302 generates a drive signal for the motor 101. A motor driver 305 drives the motor 101 based on a drive signal from the feedback drive circuit 303 or the open loop drive circuit 304. The motor drive device 1 includes the above components.

  The open loop drive circuit 304 and the motor driver 305 (first drive means) perform open loop drive (OP drive) on the motor 101. The OP driving is a driving method for switching energization to the motor coil in accordance with a predetermined time interval, similarly to the open loop control of a normal step motor. That is, the open loop drive circuit 304 and the motor driver 305 sequentially switch energization to the first coil 203 and the second coil 204 according to the drive pulse interval (drive frequency) and the rotation direction. By such control, the rotor 202 can be rotated at a desired speed (speed control). It is also possible to rotate the rotor 202 by a desired angle according to the number of drive pulses (position control).

  Thus, in OP driving, energization of the coil is switched according to a predetermined time interval (drive pulse interval). For this reason, it is possible to control the coil energization switching timing without being affected by the detection result of the position sensor. However, if the drive pulse interval is shortened, it becomes difficult for the rotor to respond to switching of the coil energization, which may cause a step-out. Therefore, the maximum speed of the rotor during OP driving is the maximum speed that the rotor can follow with respect to switching of coil energization.

  The feedback drive circuit 303 and the motor driver 305 (second drive means) perform feedback drive (FB drive) with respect to the motor 101. The FB drive is a drive method that switches energization to the motor coil in accordance with the output of a position sensor (first position sensor 207, second position sensor 208) that detects the position of the rotor 202. In other words, the feedback drive circuit 303 and the motor driver 305 are configured so that the first coil 203 and the second coil are in accordance with the number of drive pulses, the rotation direction, and the advance signal generated based on the detection signal output from the position sensor. The energization with 204 is sequentially switched. By such control, it is possible to rotate the rotor 202 by a desired angle (position control). Further, by controlling the current or voltage flowing in the first coil 203 and the second coil 204, the rotor 202 can be rotated with a desired torque (current / voltage control). Furthermore, by controlling the phase difference (advance angle) between the detection signal and the advance angle signal, it is possible to change the torque-rotation speed characteristic (advance angle control). The advance angle control will be described later.

  In the FB drive, the energization switching of the coil is performed in accordance with the position of the rotor. For this reason, the occurrence of step-out due to the response delay of the rotor can be reduced, and high-speed driving is possible.

  Next, the phase relationship between the yoke and the position sensor in the motor 101 of this embodiment will be described. FIG. 3 is a cross-sectional view in the axial direction showing the phase relationship between the yoke, the position sensor, and the rotor in the motor 101. In FIG. 3, the clockwise direction is the positive direction. 205 a to 205 d are magnetic pole teeth of the first yoke 205, and 206 a to 206 d are magnetic pole teeth of the second yoke 206. In this embodiment, the number of poles of the magnet is 8 and the magnetization angle P is 45 °. When the first yoke 205 is used as a reference, the phase P / 2 of the second yoke 206 is −22.5 °, the phase β1 of the first position sensor 207 is + 22.5 °, and the second position sensor 208 is used. The phase β2 is −45 °.

Hereinafter, the operation of the motor will be described using the electrical angle. The electrical angle is expressed by assuming that one period of the magnet magnetic force is 360 °. When the number of poles of the rotor is M and the actual angle is θ ₀ , the electrical angle θ is expressed by the following equation (1). The

θ = θ ₀ × M / 2 (1)
The phase difference between the first yoke 205 and the second yoke 206, the phase difference between the first position sensor 207 and the second position sensor 208, and the phase difference between the first yoke 205 and the first position sensor 207 are all The electrical angle is 90 °. In FIG. 3, the magnetic pole tooth center of the first yoke 205 and the north pole center of the magnet 201 are opposed to each other. This state is the initial state of the rotor, and the electrical angle is 0 °.

  Next, the relationship between the rotation angle of the rotor and the motor torque in the motor 101 and the relationship between the rotation angle of the rotor and each signal will be described. FIG. 4 is a graph showing the relationship between the rotation angle of the rotor, the motor torque, and the output of the position sensor.

  FIG. 4A is a graph showing the relationship between the rotation angle (rotor position) of the rotor and the motor torque, where the horizontal axis represents the electrical angle and the vertical axis represents the motor torque. In FIG. 4A, the motor torque that rotates the rotor clockwise is positive. When a positive current is passed through the first coil 203, the first yoke 205 is magnetized to the N pole, and an electromagnetic force is generated between the magnetic pole of the magnet 201. Further, when a positive current is passed through the second coil 204, the second yoke 206 is magnetized to the N pole, and an electromagnetic force is generated between the magnetic poles of the magnet. When the two electromagnetic forces are combined, a substantially sinusoidal torque is obtained as the rotor 202 rotates (torque curve A + B +). Similarly, a substantially sinusoidal torque can be obtained in other energized states (torque curves A + B−, AB−, and AB−). The first yoke 205 is disposed with a phase of 90 ° in electrical angle with respect to the second yoke 206. For this reason, the four torques have a phase difference of 90 ° in electrical angle.

  FIG. 4B is a graph showing the relationship between the rotation angle of the rotor (rotor position) and the output of each signal. The horizontal axis indicates the electrical angle, and the vertical axis indicates the output of each signal. The magnet 201 is magnetized so that the strength of the magnetic force in the radial direction is substantially sinusoidal with respect to the electrical angle. Therefore, a substantially sinusoidal signal is obtained from the first position sensor 207 (position sensor signal A). In the present embodiment, the first position sensor 207 outputs a positive value when facing the north pole of the magnet 201.

  The second position sensor 208 is arranged with a phase of 90 ° in electrical angle with respect to the first position sensor 207. Therefore, a substantially cosine wave-like signal is obtained from the second position sensor 208 (position sensor signal B). In the present embodiment, the second position sensor 208 has an inverted polarity with respect to the first position sensor 207. For this reason, the second position sensor 208 outputs a positive value when facing the south pole of the magnet 201.

  Outputs of the first position sensor 207 and the second position sensor 208 are subjected to a predetermined calculation by the position sensor signal processing circuit 301 and are input to an advance angle circuit constituting a part of the feedback drive circuit 303. The advance angle circuit outputs a first advance angle signal and a second advance angle signal having an arbitrary advance angle set by the control unit 302. Hereinafter, a method for calculating these advance signals will be described.

  Assuming that the electrical angle is θ, the output of the first position sensor 207 is HE1, and the output of the second position sensor 208 is HE2, each output is expressed by the following equations (2-1) and (2-2). expressed.

HE1 = sin θ (2-1)
HE2 = cos θ (2-2)
Here, if the first advance signal advanced by the advance angle α is PS1, and the second advance signal advanced by the advance angle α is PS2, the following equation (3- It can be calculated as 1) and (3-2).

PS1 = sin (θ + α) = HE1 × cos α + HE2 × sin α (3-1)
PS2 = cos (θ + α) = HE2 × cos α−HE1 × sin α (3-2)
In the present embodiment, the advance circuit is configured based on the arithmetic expressions (3-1) and (3-2). FIG. 5 is a diagram showing the configuration of the advance angle circuit 401 in the present embodiment. The advance angle circuit 401 is composed of an analog circuit as shown in FIG. 5, for example. Such an advance circuit makes it possible to realize the above calculation. First, a signal obtained by amplifying each position sensor output with a predetermined amplification factor A and a signal obtained by inverting those outputs are generated (Asin θ, Acos θ, −Asin θ, −A cos θ). These signals are multiplied by appropriate resistance values R1 and R2 and added to generate an advance angle signal. The first advance signal PS1 and the second advance signal PS2 are expressed by the following equations (4-1) and (4-2).

PS1 = A × (R / R1) × sin θ + A × (R / R2) cos θ (4-1)
PS2 = A × (R / R1) × cos θ−A × (R / R2) sin θ (4-2)
By selecting the resistor R and the variable resistors R1 and R2 in the advance angle circuit so as to satisfy the following expressions (5-1) and (5-2), an advance angle signal advanced by an arbitrary advance angle α is generated. be able to.

R / R1 = cos α (5-1)
R / R2 = sin α (5-2)
The first advance signal PS1 and the second advance signal PS2 are binarized by a comparator, and a binarized signal is output from the comparator.

  The method of generating the advance signal in the present embodiment is not limited to the method using the above-described analog circuit. An advance angle signal may be generated using a digital circuit, or an advance angle signal may be generated by adjusting a pulse interval for switching energization using a high-resolution encoder.

  Next, energization switching in the FB drive will be described. First, the operation of the FB drive when the advance angle of the advance signal output from the advance circuit is zero will be described. In FIG. 4B, the advance angle signal A and the advance angle signal B are signals obtained by performing the aforementioned advance angle calculation on the position sensor signal A and the position sensor signal B, and giving the advance angle. FIG. 4 (2) shows a case where the advance angle is zero. For this reason, the sensor signal A and the advance angle signal A, which are the outputs of the first position sensor 207, and the sensor signal B and the advance angle signal B, which are the outputs of the second position sensor 208, match each other. The binarized signal A and the binarized signal B are signals obtained by binarizing the advance angle signal A and the advance angle signal B with a comparator.

  In the FB drive, the motor driver 305 switches the energization of the first coil 203 based on the binarized signal A and switches the energization of the second coil 204 based on the binarized signal B. That is, the motor driver 305 causes a current in the positive direction to flow through the first coil 203 when the binarized signal A has a positive value, and a current in the reverse direction through the first coil 203 when the binarized signal A has a negative value. Shed. The motor driver 305 causes a current in the positive direction to flow through the second coil 204 when the binarized signal B is a positive value, and causes a current in the reverse direction to flow through the second coil 204 when the signal is negative. Shed.

  FIG. 6 is a cross-sectional view in the axial direction showing the operation during the FB drive in the motor 101 of this embodiment. FIG. 6A shows a state in which the rotor is rotated 135 ° in electrical angle. At this time, as represented by (a) in FIG. 4B, the binarized signal A indicates a positive value, and the binarized signal B indicates a negative value. Therefore, a positive current flows through the first coil 203, and the first yoke 205 is magnetized to the N pole. On the other hand, a reverse current flows through the second coil 204, and the second yoke 206 is magnetized to the south pole. At this time, the clockwise torque corresponding to the torque curve A + B- in FIG.

  FIG. 6B shows a state where the rotor 202 is rotated by 180 ° in electrical angle. At this time, the binarized signals A and B are represented by (b) in FIG. The first position sensor 207 is located at the boundary between the N pole and the S pole of the magnet 201. For this reason, the binarized signal A is switched from a positive value to a negative value at an electrical angle of 180 °, and the energization direction of the first coil 203 is switched from the positive direction to the reverse direction. This electrical angle coincides with the electrical angle at the intersection of the torque curve A + B− and the torque curve AB−.

  FIG. 6B ′ shows a state where the rotor has rotated 180 ° in electrical angle and the energization direction of the first coil 203 has been switched. A reverse current flows through the first coil 203 and the first yoke 205 is magnetized to the south pole, and a reverse current flows through the second coil 204 and the second yoke 206 is magnetized to the south pole. To do. At this time, the clockwise torque corresponding to the torque curve AB in FIG. 4A works, and the rotor 202 receives the rotational force in the θ direction and rotates.

  FIG. 6C shows a state in which the rotor 202 is rotated by 225 ° in electrical angle. At this time, as shown by (c) in FIG. 4B, the binarized signals A and B both show negative values. Accordingly, a current in the reverse direction (negative direction) flows through the first coil 203, the first yoke 205 is magnetized to the south pole, and a current in the reverse direction also flows through the second coil 204, causing the second yoke to flow. 206 is magnetized to the south pole. At this time, the clockwise torque corresponding to the torque curve AB in FIG. 4A works, and the rotor 202 receives the rotational force in the θ direction and rotates.

  FIG. 6D shows a state in which the rotor 202 is rotated by 270 ° in electrical angle. The binarized signals A and B are represented by (d) in FIG. At this time, the second position sensor 208 is located at the boundary between the N pole and the S pole of the magnet 201. For this reason, the binarized signal B is switched from a negative value to a positive value at an electrical angle of 270 °, and the energization direction of the second coil 204 is switched from the reverse direction to the positive direction. This electrical angle coincides with the electrical angle at the intersection of the torque curve AB- and the torque curve AB +.

FIG. 6 (d ′) shows a state where the rotor 202 has rotated 270 ° in electrical angle and the energization direction of the second coil 204 has been switched. A positive current flows through the second coil 204 and the second yoke 206 is magnetized in the N pole, and a reverse current flows through the first coil 203 and the first yoke 205 is magnetized in the S pole. To do. At this time, clockwise torque corresponding to the torque curve A−B + in FIG. 4A acts on the rotor 202, and the rotor 202 rotates by receiving rotational force in the θ direction.
By repeating the above operation, the rotor 202 can be continuously rotated. Further, by reversing the positive and negative values of the binarized signals A and B, it is possible to rotate them in reverse.

  Next, the operation of the FB drive when the advance signal output from the advance circuit has a predetermined advance α will be described. FIG. 7 is a graph showing the relationship between the rotation angle of the rotor, the motor torque, and the output of each signal when the advance angle signal has a predetermined advance angle α.

  FIG. 7 (1) shows the relationship between the rotation angle of the rotor (rotor position) and the motor torque, the horizontal axis shows the electrical angle, and the vertical axis shows the motor torque. FIG. 7B is a graph showing the relationship between the rotation angle of the rotor (rotor position) and the output of each signal, where the horizontal axis indicates the electrical angle and the vertical axis indicates the output of each signal. In FIG. 7 (2), the advance angle signal A is advanced with respect to the sensor signal A by a predetermined advance angle α. Similarly, the advance angle signal B is advanced by a predetermined advance angle α with respect to the sensor signal B. The binarized signals A and B generated based on the advance signals A and B are also advanced by the advance angle α with respect to the sensor signals A and B, respectively. In the FB drive, energization to the first coil 203 is switched based on the binarized signal A, and energization to the second coil 204 is switched based on the binarized signal B. For this reason, the energization switching timing of the coil is earlier by the advance angle α than when the advance angle is zero.

  FIG. 8 is a graph showing the relationship between the torque and the rotational speed when the advance angle is changed (when the advance angle value θp = 0, α). The horizontal axis represents the motor torque, and the vertical axis represents the motor speed. As shown in FIG. 8, the relationship between the torque and the rotational speed changes depending on the advance angle α. In the FB drive, the advance angle control for changing the advance angle α according to the drive condition is performed using this property. When FB driving is performed under a certain load condition, the driving speed can be controlled by controlling the advance angle α.

FIG. 9 is a diagram illustrating a driving state (from driving start to driving end) of the motor driving device in the present embodiment. In FIG. 9A, the vertical axis indicates the rotational speed (V) of the rotor 202, and the horizontal axis indicates time (t). In FIG. 9 (2), the vertical axis represents the rotational acceleration (γ) of the rotor 202, and the horizontal axis represents time (t). In FIG. 9 _{(1), t} 1 is the acceleration drive period, _{t 2} is the steady driving period, _{t 3} is the reduction drive period. Of the deceleration drive period t ₃ , t _3a is a deceleration drive period by FB drive, and t _3b is a deceleration drive period by OP drive. That is, the period from t _{1 to} t _3a is the FB driving period, and the period from t _3b is the OP driving period. P _s is a switching point from the FB drive to the OP drive. As described above, the motor driving apparatus according to the present embodiment performs FB driving from the start of driving to the switching point P _s and performs OP driving from the switching point P _s to the end of driving.

The motor drive device of this embodiment constantly monitors the rotational speed V and the rotational acceleration γ of the rotor 202. The rotational speed V and the rotational acceleration γ of the rotor 202 are calculated by the control unit 302 (calculation means) based on the outputs of the first position sensor 207 and the second position sensor. For example, the rotational speed V and the rotational acceleration γ can be calculated by monitoring the rising timing (time interval) of the binarized sensor signal of (2) of FIG. 4 or (2) of FIG. In the OP drive, when the rotational speed V of the rotor 202 becomes higher than the maximum speed that the rotor 202 can follow to switch the energization to the coil, there is a possibility of causing step-out or vibration. Therefore, OP driving the rotor 202 can be executed only in the following maximum velocity V _s capable of following. Therefore, the condition of the switching point P _s is that the rotational speed V is first lower than the maximum speed of the rotor during OP driving (open loop driving) (lower than OP driving maximum speed V _s ).

In acceleration drive period _{t 1,} the rising in FB driven from a stopped state, the rotor 202 reaches the maximum rotational speed _{V m} by the driving voltage _{V a} from the motor driver 305. After the rotor 202 has reached the maximum rotational speed V _m, the FB driven at a constant speed at constant drive period t ₂ is performed. Here, the constant speed is not limited to a strictly constant speed, but includes a substantially constant speed that is evaluated as a substantially constant speed.

Thereafter, the deceleration is performed toward the target position at a reduced driving period t _3. In the deceleration driving period _{t 3a} by FB driving, for example, performs deceleration by reducing the drive voltage to _V b _{(<V a).} As a method for reducing the drive voltage, for example, when the drive signal is a PWM signal, a method for reducing the duty ratio is used. Such deceleration can also be achieved by controlling the amount of current to the exciting coil or by controlling the advance angle.

P _m in the deceleration driving period t _3a is the maximum point of deceleration acceleration (rotational acceleration γm) by FB driving. In the deceleration driving period _{t 3a,} through the maximum point _{P m} of the deceleration (rotational acceleration .gamma.m), to decelerate the rotor 202 by FB drive until the following OP drive maximum speed _{V s.} After passing the maximum point P _m, after the rotational acceleration of the rotor 202 is controlled to be equal to or less than the rotational acceleration gamma] s, in a state where the rotor 202 becomes substantially constant speed, the OP driven from FB driven at the switching point P _s Switch. Thereafter, in the deceleration driving period _t3b by OP driving, driving to the target position is performed by OP driving according to a predetermined driving frequency. In this embodiment, after the rotor 202 reaches the OP drive maximum speed V _s or less, the rotor 202 is driven at a substantially constant speed for a predetermined period (constant speed period t _c ). This constant speed drive is performed, for example, by calculating the input value to the motor from the deviation between the target position and speed and the actual position and speed, the integrated value of the deviation, etc., and adjusting the advance value and drive voltage. ing.
As described above, by shifting to the OP drive while the speed change of the rotor 202 is reduced, stable switching from the FB drive to the OP drive becomes possible. The control unit 302 switches between the first driving unit that performs OP driving and the second driving unit that performs FB driving. After switching to OP driving, deceleration driving is performed according to a predetermined driving table (data indicating the driving frequency corresponding to each remaining pulse) stored in the storage means in the control unit 302, and stops at the target position.

The motor drive device of the present embodiment drives the motor by combining the OP drive and the FB drive, so that the rotor (with the same accuracy as the normal step motor and at a higher speed than the normal step motor) Driven body) can reach the target position. While the rotation speed of the rotor in which the rotational speed of the maximum speed V _s or less and the rotor in the OP driven at a constant speed, switching from FB drive to the OP drive. For this reason, according to the present Example, the motor drive device which suppressed the occurrence of step-out and vibration can be provided.

  The embodiment of the present invention has been specifically described above. However, the present invention is not limited to the matters described as the above-described embodiments, and can be appropriately changed without departing from the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Motor drive device 101 Motor 202 Rotor 203 1st coil 204 2nd coil 207 1st position sensor 208 2nd position sensor 302 Control part 303 Feedback drive circuit 304 Open loop drive circuit 305 Motor driver

Claims (2)

A first driving means for driving the motor in an open loop by switching energization to a coil of the motor according to a predetermined time interval;
Second driving means for feedback driving the motor by switching energization to the coil of the motor according to the output of a position sensor for detecting the position of the rotor;
Arithmetic means for calculating the speed and acceleration of the rotor from the output of the position sensor;
Control means for controlling the drive of the motor by switching between the first drive means and the second drive means,
The control means performs acceleration, constant speed, and deceleration driving of the rotor by the second driving means, and when switching from the feedback driving to the open loop driving, the speed of the rotor is the same as that during the open loop driving. A motor driving apparatus characterized in that the motor is driven and controlled by the second driving means so that the speed is equal to or less than a maximum speed of the rotor and a constant speed.   The motor driving apparatus according to claim 1, wherein the deceleration driving by the second driving unit is driving by advance angle control.