JP5882639B2 - Motor drive device and drive control method for motor drive device - Google Patents

Description

The present invention relates to a drive control method of a motor drive equipment and the motor driving device.

  Conventionally, when starting a motor, first, after performing open loop control that performs drive control in synchronization with a predetermined drive frequency, drive control is performed based on a detection signal from a detection sensor that detects the rotation phase of the rotor. Switch to the feedback control to be performed. At this time, if rotation unevenness occurs due to some factor such as disturbance of the motor, there is a problem that switching from the open loop control to the feedback control is not performed smoothly. Therefore, in order to solve such a problem, a brushless motor control device as disclosed in Patent Document 1 is disclosed. In this brushless motor control device, the phase of the drive signal for synchronous mode operation, which is open loop control, and the drive signal for phase detection mode operation, which is feedback control, is compared by a comparison circuit. When the value becomes zero, the operation shifts from the synchronous mode operation to the phase detection mode operation. Then, in the synchronous mode operation, the phase detection signal information from the phase detection circuit is added to the drive signal from the control unit, and the phase difference between the drive signal and the drive signal for the phase detection mode operation is compared by the comparison circuit. The phase difference is made small.

JP-A-7-87783

  However, in the conventional technique disclosed in Patent Document 1, the drive signal for the synchronous mode operation and the drive signal for the phase detection mode operation are compared, and the synchronous mode operation is controlled so that the difference is reduced. This increases the cost due to the addition of the comparison circuit. Moreover, since it is necessary to change the switching timing at the time of the synchronous mode operation at the time of starting, there also arises a problem that the control becomes complicated. Further, in spite of the synchronous operation mode, the driving itself so as to synchronize with the phase detection mode operation has already performed the same control as the position detection operation mode. Therefore, control deviates from the concept of switching control that switches from synchronous operation at a constant speed to position feedback operation, which is a general control method, and problems such as step-out are likely to occur due to the influence of speed fluctuations.

  The present invention has been made in view of such circumstances, and is a motor drive device that can be activated by a general control method with an inexpensive circuit configuration and can realize an appropriate recovery operation when an error occurs. The purpose is to provide.

In order to achieve the above object, a motor drive device according to one aspect of the present invention includes a motor including a rotor magnet and a detector that detects a rotational position of the rotor magnet, and an output from the detector within a predetermined range. Determination means for determining whether or not, a first drive means for driving the motor by open loop control, a second drive means for driving the motor by feedback control, and at the start of driving of the motor, After the motor is driven from a predetermined driving frequency by the first driving means, the motor is driven at a predetermined acceleration by the second driving means when the speed of the motor becomes the first speed. as such, and a control means for switching between said first driving means and said second drive means drives said motor by said first drive means When that, when said determination means determines that the output from the detector is outside of the predetermined, wherein the control unit, the speed of the motor becomes lower than said first speed second speed when the, and wherein the switching Rukoto from driving of said motor by said first drive means to drive said motor by said second drive means.

  According to the present invention, it is possible to perform startup by a general control method with an inexpensive circuit configuration and to realize an appropriate recovery operation when an error occurs.

It is a disassembled perspective view of the stepping motor used for the Example of this invention. It is a block diagram which shows the structure of the motor control apparatus of this invention. It is an axial direction sectional view showing the phase relation of a yoke, a position sensor, and a rotor. It is a figure which shows the relationship between the rotational position of a rotor, and a motor torque, and the relationship between a rotor position and the output of a position sensor. It is a circuit diagram which shows the structure of an advance angle circuit. It is an axial sectional view showing the operation of feedback drive. It is a figure which shows the relationship between the rotation angle of a rotor, the motor torque, and the output of each signal in case the advance angle signal output from an advance angle circuit has the predetermined advance angle (alpha). It is a figure which shows the relationship between the torque when changing an advance angle, and rotation speed. It is a velocity diagram which shows a mode when starting a motor. It is a flowchart at the time of starting of this invention. It is an external view of an imaging device using the motor control device of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of a stepping motor 101 used in the embodiment of the present invention.

  First, the component configuration of the stepping motor 101 will be described. The rotor 202 has a rotor magnet 202a and a shaft portion 202b. The first bearing 403 and the second bearing 404 each support the shaft portion 202b. The first coil 203 is wound around a bobbin 401 formed of a nonconductive member. The second coil 204 is wound around a bobbin 402 formed of a nonconductive member. The first yoke 205 and the second yoke 206 are made of electromagnetic steel plates or the like. The ring member 405 positions the first yoke 205, the second yoke 206, the bobbin 401, and the bobbin 402, respectively. The flexible printed circuit board 406 is electrically connected to the first coil 203 and the second coil 204. On the flexible printed circuit board 406, a first position sensor 207 and a second position sensor 208, which are rotational position detectors of the rotor magnet 202a, are mounted in the circumferential direction of the rotor. The rotor magnet 202a is a cylindrical permanent magnet whose outer periphery is multipolarized. 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.

  Next, the correlation between the components will be described. The rotor 202 is pivotally supported by the first bearing 403 on the long axis side and the second bearing 404 on the short axis side. The first bearing 403 is inserted into a hole (an inner diameter portion of the first coil 203) 401a provided in the bobbin 401. The second bearing 404 is inserted into a hole (an inner diameter portion of the second coil 204) 402a provided in the bobbin 402. The outer diameter portion of the first bearing 403 is fixed to the hole 205a of the first yoke 205 by press-fitting. The outer diameter portion of the second bearing 404 is fixed to the hole portion 206a of the second yoke 206 by press fitting. At that time, the tooth portion 205 b of the first yoke 205 is inserted into the hole portion 401 b provided in the bobbin 401. The tooth portion 206 b of the second yoke 206 is inserted into a hole portion 402 b provided in the bobbin 402.

  As described above, the bobbin (including the coil) 401, the first yoke 205, and the first bearing 403 are integrated. Similarly, the bobbin (including the coil) 402, the second yoke 206, and the second bearing 404 are integrated. Then, the inner diameter portions 401c and 402c of the bobbin are fitted into the outer diameter portion 405a of the ring member 405, respectively. At this time, the teeth 205b of the first yoke 205 and the tips of the teeth 206b of the second yoke 206 are arranged so that the vicinity of the tips of the rotor 202 faces the magnet surface.

  FIG. 2 is a block diagram showing the configuration of the motor drive device of this embodiment. A position sensor signal processing circuit (determination means) 301 processes the above-described stepping motor 101 and outputs of the first position sensor 207 and the second position sensor 208 included in the stepping motor 101. The output from the position sensor signal processing circuit 301 is input to the control unit 302 and the feedback drive circuit (second drive means) 303. The control unit 302 functions as a control unit that selects either driving by feedback control or driving by open loop control and outputs the number of driving pulses and the rotation direction. The feedback drive circuit 303 is selected by the control unit 302 and functions as a feedback drive unit that generates a drive signal for the stepping motor 101. The open loop drive circuit (first drive unit) 304 is selected by the control unit 302 and functions as an open loop drive unit that generates a drive signal for the stepping motor 101. The drive pulse output from the feedback drive circuit 303 and the drive pulse output from the open loop drive circuit 304 are supplied to the stepping motor 101 via the motor driver 305.

  Next, driving by open loop control of the stepping motor 101 (hereinafter referred to as open loop driving) will be described.

  When the control unit 302 selects the open loop drive, the control unit 302 outputs the number of drive pulses and the rotation direction to the open loop drive circuit 304. The open loop drive circuit 304 outputs a drive pulse at a preset time interval to the motor driver 305 according to the input drive pulse number and rotation direction. The motor driver 305 sequentially switches the energization pattern of the first coil 203 and the second coil 204 according to a driving pulse at a preset time interval. In the open loop drive, it is possible to change the rotational speed of the rotor 202 by changing the time interval of the drive pulses output from the open loop drive circuit 304. Further, since the open loop drive circuit 304 outputs drive pulses for the number of drive pulses input from the control unit 302, the rotation amount of the rotor 202 can be controlled.

  In the open loop drive, the energization patterns of the first coil 203 and the second coil 204 are switched at a preset time interval.

  If the drive pulse time interval is shortened during open-loop driving, the rotor cannot respond to the switching of the energization pattern of the first coil 203 and the second coil 204, and the possibility of step-out occurs. There is. For this reason, the high speed driving in the open loop driving is within a range in which the rotor can respond to switching of the energization patterns of the first coil 203 and the second coil 204.

  Next, driving by feedback control of the stepping motor 101 (hereinafter referred to as feedback driving) will be described.

  When the control unit 302 selects feedback driving, the control unit 302 outputs the number of driving pulses and the rotation direction to the feedback driving circuit 303. The feedback drive circuit 303 outputs drive pulses at predetermined time intervals to the motor driver 305 according to the input drive pulse number and rotation direction. The time interval of the drive pulses output from the feedback drive circuit 303 varies depending on the outputs of the first position sensor 207 and the second position sensor 208. The motor driver 305 sequentially switches energization patterns of the first coil 203 and the second coil 204 in accordance with drive pulses at time intervals that change according to the outputs of the first position sensor 207 and the second position sensor 208. In the feedback drive, the feedback drive circuit 303 outputs drive pulses for the number of drive pulses input from the control unit 302, so that the rotation amount of the rotor 202 can be controlled. Further, the feedback drive circuit 303 includes an advance angle circuit, and the advance angle circuit generates an advance angle signal from the outputs of the first position sensor 207 and the second position sensor 208. The feedback drive circuit 303 can change the torque-rotation speed characteristic of the stepping motor 101 by controlling the advance amount. The advance angle control will be described later.

  In the feedback drive, the energization patterns of the first coil 203 and the second coil 204 are switched at time intervals that change according to the outputs of the first position sensor 207 and the second position sensor 208. Since the energization pattern of the first coil 203 and the second coil 204 is switched according to the position of the rotor 202, the occurrence of step-out due to the response delay of the rotor 202 can be reduced, and high-speed driving is possible compared to open loop driving It becomes possible.

  Next, the phase relationship between the yoke and the position sensor in the stepping motor 101 will be described.

FIG. 3 is an axial cross-sectional view showing the phase relationship among the yoke, the position sensor, and the rotor. In the figure, the clockwise direction is the positive direction. 205b _{1 to} b ₄ are magnetic pole teeth of the first yoke 205, and 206b _{1 to} b ₄ 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 is used as a reference, the phase P / 2 of the second yoke is −22.5 °, the phase β1 of the first position sensor 207 is + 22.5 °, and the phase of the second position sensor 208. β2 is −45 °.

In the following description, the operation of the motor will be described using the electrical angle. The electrical angle represents one period of magnet magnetic force as 360 °. When the number of poles of the rotor is M and the actual angle is θ ₀ , the electrical angle θ can be expressed by the following equation.

θ = θ ₀ × M / 2 (Formula 1-1)
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 electric. The angle is 90 °. In FIG. 3, the center of the magnetic pole teeth of the first yoke faces the center of the N pole of the rotor magnet 202a. This state is the initial state of the rotor and the electrical angle is 0 °.
(Relationship between rotor position and motor torque, relationship between rotor position and sensor output)
Here, the relationship between the rotor position and the motor torque in the stepping motor 101 and the relationship between the rotor position and the sensor output will be described.

  FIG. 4 is a graph showing the relationship between the rotational position of the rotor and the motor torque, and the relationship between the rotational position of the rotor and the output of the position detection sensor.

  FIG. 4A is a graph showing the relationship between the rotation angle of the rotor and the motor torque, where the horizontal axis indicates the electrical angle and the vertical axis indicates the motor torque. The motor torque is positive when the rotor rotates clockwise.

  When a positive current is passed through the first coil 203, the first yoke 205 is magnetized to the north pole, and an electromagnetic force is generated between the magnetic pole of the rotor magnet 202a. 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 roughly sinusoidal torque is obtained as the rotor 202 rotates (torque curve A + B +). Similarly, in the other energized state, a substantially sinusoidal torque is obtained (torque curves A + B−, AB−, AB +). Further, since the first yoke 205 is arranged with a phase of 90 ° in electrical angle with respect to the second yoke 206, 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 and the output of each signal. The horizontal axis indicates the electrical angle, and the vertical axis indicates the output of each signal.

  The magnitude of the radial magnetic force of the rotor magnet 202a is magnetized so as to be approximately 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 rotor magnet 202a.

  Further, since the second position sensor 208 is arranged with a phase of 90 ° in electrical angle with respect to the first position sensor 207, a cosine wave-like signal is obtained from the second position sensor 208 (position sensor signal). B). In the present embodiment, since the second position sensor 208 has the polarity reversed with respect to the first position sensor 207, the second position sensor 208 outputs a positive value when facing the S pole of the rotor magnet 202a.

  The advance angle circuit included in the feedback drive circuit 303 performs a predetermined calculation based on the output of the first position sensor 207 and the output of the second position sensor 208 processed by the position sensor signal processing circuit 301. . Then, the first advance angle signal and the second advance angle signal are output by the advance angle circuit. Hereinafter, a method for calculating the advance angle signal will be described.

  When the electrical angle θ, the output of the first position sensor 207 is HE1, and the output of the second position sensor 208 is HE2, each signal is expressed as follows.

HE1 = sin θ, HE2 = cos θ (Formula 2-1)
Further, assuming that the first advance signal obtained by advancing HE1 by the advance angle α is PS1, and the second advance signal obtained by advancing HE2 by the advance angle α is PS2, using HE1, HE2, and α as follows: It is possible to calculate

PS1 = sin (θ + α) = HE1 × cosα + HE2 × sinα (Formula 3-1)
PS2 = cos (θ + α) = HE2 × cos α−HE1 × sin α (Formula 3-2)
In this embodiment, an advance angle circuit is configured based on this arithmetic expression.

  FIG. 5 is a circuit diagram showing the configuration of the advance angle circuit. The above calculation can be realized by configuring the advance circuit in this embodiment with an analog circuit as shown in FIG. 5, for example. First, a signal obtained by amplifying each position sensor output by a predetermined amplification factor A and a signal obtained by inverting them are generated. An advance angle signal is generated by adding the appropriate resistance values R1 and R2 and adding them. The first advance signal PS1 and the second advance signal PS2 are expressed as follows.

PS1 = A × (R / R1) × sin θ + A × (R / R2) cos θ (Formula 4-1)
PS2 = A × (R / R1) × cos θ−A × (R / R2) sin θ (Formula 4-2)
By selecting the variable resistors R, R1, and R2 in the circuit as follows, an advance angle signal advanced by an arbitrary advance angle α can be generated.

R / R1 = cos α, R / R2 = sin α (Formula 5-1)
Further, a binary signal obtained by binarizing the first advance signal PS1 and the second advance signal PS2 using a comparator is output.

  The method for generating the advance signal described above is an example for realizing the present invention, and is not limited to this method. The advance angle signal may be generated by a digital circuit that performs the above calculation, or the advance angle signal may be generated by adjusting a pulse interval for switching energization using a high-resolution encoder. Even if these well-known methods are used, the same effect as the above-described method of generating the advance angle signal can be obtained.

  Here, energization switching in feedback driving will be described. First, the feedback drive operation will be described for the case where the advance angle of the advance signal output from the advance circuit is zero.

  In FIG. 4B, position sensor signals A and B are the outputs of the first and second position sensors 207 and 208, respectively. The binarized signals A and B are signals obtained by binarizing the position sensor signals A and B using a comparator.

  In the feedback drive, the energization of the first coil 203 is switched based on the binarized signal A, and the energization of the second coil 204 is switched based on the binarized signal B. That is, when the binarized signal A indicates a positive value, a current in the positive direction is passed through the first coil 203, and when the binary signal A indicates a negative value, a current in the reverse direction flows through the first coil 203. Further, when the binarized signal B shows a positive value, a current in the positive direction is passed through the second coil 204, and when it shows a negative value, a current in the reverse direction flows through the second coil 204.

  FIG. 6 is a sectional view in the axial direction showing the operation of feedback driving.

  FIG. 6A shows a state in which the rotor is rotated 135 ° in electrical angle. The position sensor signals A and B indicate the values shown in FIG. 4B, the binarized signal A is positive, and the binarized signal B indicates a negative value. Accordingly, a positive current flows through the first coil 203 and the first yoke 205 is magnetized in the N pole, and a reverse current flows through the second coil 204 and the second yoke 206 is in the S pole. Is magnetized. At this time, a clockwise torque corresponding to the torque curve A + B− in FIG. 4A is applied, and the rotor 202 rotates in response to the rotational force in the θ direction.

  FIG. 6B shows a state where the rotor 202 is rotated by 180 ° in electrical angle. The first position sensor 207 is located at the boundary between the N pole and the S pole of the rotor magnet 202a. For this reason, the binarized signal A is switched from a positive value to a negative value at the 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 degrees 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, a clockwise torque corresponding to the torque curve AB in FIG. 4A is applied, and the rotor 202 rotates in response to the rotational force in the θ direction.

  FIG. 6C shows a state in which the rotor 202 is rotated by 225 ° in electrical angle. Each advance angle signal indicates the value indicated by (C) in FIG. 4B, and both binarized signals A and B indicate negative values. Accordingly, 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 flows through the south pole. Is magnetized. At this time, a clockwise torque corresponding to the torque curve AB in FIG. 4A is applied, and the rotor 202 rotates in response to the rotational force in the θ direction.

  FIG. 6D shows a state in which the rotor 202 is rotated by 270 ° in electrical angle. The second position sensor 208 is located at the boundary between the N pole and the S pole of the rotor magnet 202a. 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. 6D 'shows a state where the rotor has rotated 270 ° in electrical angle and the energization direction of the second coil 204 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 positive current flows through the second coil 204 and the second yoke 206 is magnetized to the north pole. To do. At this time, a clockwise torque corresponding to the torque curve A-B + in FIG. 4A is applied, and the rotor 202 rotates in response to the rotational force in the θ direction.

  By repeating the above operation, the rotor 202 can be continuously rotated. Further, if the sign of the binarized signal A or the binarized signal B is inverted, reverse rotation is also possible.

  Next, the feedback drive operation when the advance signal output from the advance circuit has a predetermined advance angle 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 signal output from the advance circuit has a predetermined advance angle α.

  FIG. 7B is a graph showing the relationship between the rotation angle of the rotor 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. 7B, the advance angle signals A and B are advanced by a predetermined advance angle α with respect to the sensor signals A and B, respectively. Further, the binarized signals A and B generated based on the advance angle signal also advance by the advance angle α with respect to the sensor signals A and B, respectively. In the feedback drive, the energization of the first coil is switched based on the binarized signal A, and the energization of the second coil is switched based on the binarized signal B. The advance angle α is faster than when it is zero.

  FIG. 8 is a graph showing the relationship between torque and rotational speed when the advance angle is changed. The horizontal axis represents the motor torque, and the vertical axis represents the motor speed.

  From the graph, it can be seen that the relationship between the torque and the rotational speed changes depending on the advance angle α. Using this property, in the feedback drive, advance angle control is performed to change the advance angle α according to the drive conditions. When feedback driving is performed under a constant load condition, the driving speed can be controlled by controlling the advance angle α.

  By controlling by combining open loop drive and feedback drive as described above, it is possible to stop at the target position with the same accuracy as a normal step motor and to reach the target position faster than a normal step motor. It becomes. Then, when an out-of-step error occurs due to the influence of a disturbance load during open loop driving or acceleration control in feedback driving, it is possible to perform more reliable start-up by performing the following control.

FIG. 9 is a velocity diagram showing a state when the stepping motor 101 is activated. The horizontal axis represents time, and the vertical axis represents speed. At the time of normal startup, acceleration driving is _{first performed} by open-loop driving up to a predetermined speed V _{1, and} then switching to feedback driving is performed at time t ₁ (P ₁ point). Thereafter, after acceleration to speed V ₂ by feedback driving, constant speed driving is started at time t ₂ .

In FIG. 9A, it is assumed that the motor is not synchronized due to some factor at time t ₄ (speed V ₃ ) in the middle of feedback driving, and the step-out is stopped at a speed curve as indicated by 901. At this time, since the motor 101 is provided with the two position sensors 207 and 208 as described above, it is possible to determine that the motor has stopped stepping out during the start for some reason. At this time, since an abnormality has occurred at time t ₄ (speed V ₃ ), it can also be determined that an error has stopped during acceleration by feedback driving.

In restarting the motor, since there is no abnormality from the open loop drive to the feedback drive switching in the previous start, the open loop drive itself is open loop driven so that the speed becomes V ₁ at time t ₁ as in the previous case. Accelerate by. Thereafter, in acceleration by feedback driving, acceleration driving in feedback driving is performed so that the acceleration is lower than the previous acceleration. Specifically, it performs a low acceleration start than previous As a V ₂ from the speed V ₁ during the period from the time t ₁ as shown in 902 shown in FIG. 9 (a) to t _3. Thus, by performing acceleration driving in feedback driving with low acceleration, it is possible to perform feedback driving that avoids a step-out error.

Next, in FIG. 9B, it is assumed that the motor becomes unsynchronized due to some factor at time t5 (speed V4) in the middle of acceleration by the open loop drive, and the rotation stops along the speed curve as indicated by 903. . At this time as well, the two position sensors 207 and 208 as described above can determine that the motor has stopped stepping out during the start for some reason. At this time, since a problem has occurred at time t5 (speed V4), it can also be determined that an error has occurred during acceleration by open-loop driving. Accordingly, when the motor is restarted, the open loop drive frequency is set to a lower value than the previous time, and the switching point P2 (time t1) having a lower rotational speed than the switching point P1 from the normal open loop drive to the feedback drive. , Speed V5). At this time, in FIG. 9B, the acceleration is controlled at the same acceleration as the previous time, but the acceleration may be controlled to be low. In other words, it is possible to accelerate slowly so that the time to reach the speed V5 is longer than t1, that is, the inclination of the graph is reduced. And after synchronizing with the speed V5 reliably by open loop drive, it switches to feedback drive at the switching point P2, and performs acceleration drive.

  At this time, it is possible to control the acceleration more reliably by setting the acceleration of the feedback drive to be lower than usual. By performing such restart control, restart is performed in accordance with a speed curve as shown at 904 in FIG. 9B, switching from open loop drive to avoid feedback error, and acceleration drive by feedback drive. Can be done.

FIG. 10 is a start-up flowchart showing the above-described drive control contents in a flow.
The activation control will be briefly described again along the flow. First, in the main startup flow, when a startup subroutine is started in S101, acceleration by open loop driving, which is step driving, is performed in S102. At this time, step-out error determination is performed using detection signals from the two position sensors 207 and 208. Specifically, since the signals to be detected in time series in the forward rotation and the reverse rotation are determined, the order of the signals to be detected and the difference in the detection signal value with respect to the driving cycle are monitored to step out and stop. Make a decision. At this time, if the detection signal is within a predetermined range, there is no problem. When a predetermined switching frequency for feedback driving is reached, switching to feedback driving is performed in S104, and acceleration driving by feedback driving is performed. If there is no problem after performing whether or not the detection signal is within the predetermined range in the step S105 during the feedback driving as well, the process exits the start control routine in the step S106.

Next, control when an error occurs will be described. If rotation abnormality is detected in S103 during acceleration by open-loop driving because the detection signal is outside the predetermined range, the number of errors is confirmed in S201. If a predetermined number of errors have occurred, the start control is stopped and the error is stopped in S202. If the specified number of times has not been reached, the open loop drive frequency is set to a lower value than the previous time in S203, and the process returns to S102 to try again. Then, the switching point from the open loop driving to the feedback driving is set to the switching point P2 having a lower rotational speed than the normal switching point P1. At this time, as shown in FIG. 11, for example, “ERROR” is displayed on the display unit 1201 a provided in the optical device such as the digital camera 1201 to stop the operation of the device. Next, when an abnormality is detected in S105 when the detection signal is outside the predetermined range during acceleration driving by feedback driving, the number of occurrences of errors is confirmed in S301 as described above. Also here, when a predetermined number of errors have occurred, the start control is stopped and the error is stopped in S302. At this time, similarly to the above, for example, “ERROR” is displayed on the display unit 1201a provided in the optical device such as the digital camera 1201, and the operation of the device is stopped. If the number of error occurrences has not reached the specified number, the process proceeds to S303, the acceleration of feedback drive is set lower than the previous time, and then the process returns to S102 to restart.

  As described above, even if the motor stops due to some factor during switching acceleration from open loop drive to feedback drive, optimal start-up control can be performed while appropriately changing each parameter, improving motor drive reliability It can be made.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. For example, it is possible to reduce the open-loop drive synchronization speed from the previous time and restart the feedback drive acceleration lower than the previous time, even if the error stop is either open-loop drive or feedback drive. It is.

  The start-up reliability of the brushless motor can be improved by an inexpensive and simple drive control method.

101 Stepping motor 301 Position sensor signal processing circuit 302 Control unit 303 Feedback drive circuit 304 Open loop drive circuit

Claims (4)

A motor comprising a rotor magnet and a detector for detecting the rotational position of the rotor magnet;
Determining means for determining whether the output from the detector is within a predetermined range;
First driving means for driving the motor by open loop control;
Second driving means for driving the motor by feedback control;
At the start of driving of the motor, after the motor is driven from a predetermined driving frequency by the first driving means, the motor is driven by the second driving means when the speed of the motor becomes the first speed. Control means for switching between the first drive means and the second drive means so as to drive at a predetermined acceleration ,
When the determination unit determines that the output from the detector is out of the predetermined range when the motor is driven by the first driving unit, the control unit determines that the speed of the motor is when a first lower than the speed second speed, the motor drive, wherein the switching Rukoto to drive said motor by said second drive means from the drive of the motor by said first drive means apparatus. When the determination unit determines that the output from the detector is outside the predetermined range when the motor is driven by the second driving unit, the second driving unit The motor driving apparatus according to claim 1 , wherein the motor is driven at an acceleration lower than the acceleration of the motor. When the determination unit determines that the output from the detector is outside the predetermined range when the motor is driven by the first driving unit, the first driving unit The motor driving apparatus according to claim 1, wherein the motor is driven at a driving frequency lower than the driving frequency. A motor including a rotor magnet and a detector that detects a rotational position of the rotor magnet; a determination unit that determines whether or not an output from the detector is within a predetermined range; and A motor drive device comprising: first drive means for driving; second drive means for driving the motor by feedback control; and control means for switching between the first drive means and the second drive means. Drive control method,
At the start of driving of the motor, after the motor is driven from a predetermined driving frequency by the first driving means, the motor is driven by the second driving means when the speed of the motor becomes the first speed. The control means switches between the first drive means and the second drive means so as to drive at a predetermined acceleration,
When the determination unit determines that the output from the detector is out of the predetermined range when the motor is driven by the first driving unit, the control unit determines that the speed of the motor is A motor driving device that switches from driving the motor by the first driving means to driving the motor by the second driving means when the second speed is lower than the first speed. Drive control method.