JP2017158343A - Control apparatus and control method for permanent magnet synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a response time from command to restart in a case where restart is commanded in a free-run state.SOLUTION: The control method for a permanent magnet synchronous motor in which a rotor using a permanent magnet rotates by a rotating magnetic field due to a current flowing through a winding, includes: when the rotor is stopped by an input of a stop command to bring the rotor to be in a free-run state and when a start-up command is input, detecting a current flowing through the winding; estimating a magnetic pole position and rotation speed of the rotor on the basis of the detected current; and making a current pass through the winding so as to generate a rotating magnetic field on the basis of the estimated magnetic pole position and rotational speed to drive the rotor.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a control device and a control method for a permanent magnet synchronous motor.

  In general, a permanent magnet synchronous motor (PMSM) has a stator having a winding and a rotor using a permanent magnet, and a rotating magnetic field is generated by flowing an alternating current through the winding to generate a rotating magnetic field. Rotate the child synchronously with it.

  In recent years, sensorless permanent magnet synchronous motors have been widely used. The sensorless type does not have a magnetic sensor or an encoder for detecting the magnetic pole position. For this reason, for driving the sensorless permanent magnet synchronous motor, for example, a method of estimating the magnetic pole position of the rotor based on the induced voltage generated in the winding of the stator during rotation is used.

  In addition, there is a method called inductive sensing as a method for estimating the magnetic pole position of the rotor when the sensorless permanent magnet synchronous motor is stopped. In this method, a magnetic pole position is estimated by applying a voltage between the winding phases and comparing peak amplitude values of currents flowing at that time. According to this method, regardless of the rotation position of the rotor, the rotation can be started by appropriately exciting the stator according to the magnetic pole position of the rotor.

  As a prior art for restarting (restarting) driving from a free-running state in which the sensorless permanent magnet synchronous motor stops driving after inertia, there is a technique described in Patent Document 1.

  Patent Document 1 discloses that the rotation position is continuously detected after the driving is stopped and the rotation period is calculated.

Japanese Patent Laid-Open No. 7-245983

  When a restart is commanded when the sensorless permanent magnet synchronous motor is in a free-running state, in general, the magnetic pole position is estimated by inductive sensing after waiting for the elapse of a predetermined time when the rotation stops. Then, control for restarting driving is performed. For this reason, there has been a problem that the response time from when the restart is commanded to when the driving is restarted is long. This problem is that in an image forming apparatus such as a copier or a printer, the time from when the user issues a print instruction until the first print is completed, that is, FPOT (First Print Output Time) performance is improved. It was difficult.

  The technique of Patent Document 1 described above has a problem in responsiveness because the rotational position is detected uselessly even when restart is not instructed as a result.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to shorten a response time from a command to a restart when a restart is commanded in a free-run state.

  A control device according to an embodiment of the present invention is a control device for a permanent magnet synchronous motor in which a rotor using a permanent magnet is rotated by a rotating magnetic field generated by a current flowing in a winding, and the rotor is configured to pass a current through the winding. Estimated by the estimation unit, a current detection unit that detects a current flowing in the winding, an estimation unit that estimates a magnetic pole position and a rotation speed of the rotor based on the detected current A control unit that controls the drive unit so as to generate the rotating magnetic field based on the magnetic pole position and the rotation speed, and controls start and stop of the drive unit based on the input start command and stop command And having. When the start command is input when the rotor is in a free-run state due to the drive unit being stopped by the input of the stop command, the control unit is estimated based on the current detected at that time The driving unit is restarted so that the rotating magnetic field is generated based on the magnetic pole position and the rotation speed of the rotor.

  Preferably, the control unit includes a short brake control unit that controls the drive unit so as to form a current loop due to a counter electromotive force generated in the winding, and the control unit receives the stop command when performing the restart. When input, the short brake control unit forms the current loop, and controls the drive unit based on the magnetic pole position and the rotational speed estimated based on the current detected in the current loop.

  According to the present invention, it is possible to shorten the response time from the command to the restart when the restart is commanded in the free-run state.

1 is a diagram illustrating an outline of a configuration of an image forming apparatus including a motor control device according to an embodiment of the present invention. It is a figure which shows typically the structure of a brushless motor. It is a figure which shows an example of a functional structure of a motor control apparatus. It is a figure which shows the structure of the motor drive part and electric current detection part in a motor control apparatus. It is a figure which shows the current loop by short brake control. It is a figure which shows a zero cross point. It is a figure which shows the flow of the motor control process in a motor control apparatus. It is a figure which shows the 1st example of transition of the rotational speed from a drive stop to a restart. It is a figure which shows the example of the transition of the electric current before and behind restart, and the excitation pattern after restart. It is a figure which shows the flow of the 1st example of a restart process. It is a figure which shows the 2nd example of transition of the rotational speed from a drive stop to restart. It is a figure which shows the flow of the 2nd example of a restart process. It is a figure which shows the 3rd example of transition of the rotational speed from a drive stop to restart. It is a figure which shows the flow of the 3rd example of a restart process. It is a figure which shows the 4th example of transition of the rotational speed from a drive stop to restart. It is a figure which shows the flow of the 4th example of a restart process. It is a figure which shows the 5th example of transition of the rotational speed from a drive stop to restart. It is a figure which shows the flow of the 5th example of a restart process.

  FIG. 1 shows an outline of the configuration of an image forming apparatus 1 including a motor control device 21 according to an embodiment of the present invention, and FIG. 2 schematically shows the configuration of a brushless motor 3.

  In FIG. 1, an image forming apparatus 1 is an electrophotographic color printer. The image forming apparatus 1 includes four imaging stations 11, 12, 13, and 14, which are arranged in parallel with four color toner images of yellow (Y), magenta (M), cyan (C), and black (K). To form. Each of the imaging stations 11, 12, 13, and 14 includes a cylindrical photosensitive member, a charging charger, a developing device, a cleaner, a light source for exposure, and the like.

  The four-color toner images are primarily transferred to the intermediate transfer belt 16 and secondarily transferred to the paper 9 that has been pulled out of the paper cassette 10 by the paper feed roller 15 and conveyed. After the secondary transfer, the sheet 9 passes through the inside of the fixing device 17 and is sent to the upper discharge tray 18. When passing through the fixing device 17, the toner image is fixed on the paper 9 by heating and pressing.

  In the image forming apparatus 1, the brushless motor 3 is used as a drive source for rotationally driving the fixing device 17, the intermediate transfer belt 16, the paper feeding roller 15, the photoconductor, and the developing device.

  In FIG. 2A, the brushless motor 3 is a sensorless permanent magnet synchronous motor (PMSM). The brushless motor 3 includes a stator 31 that generates a rotating magnetic field and a rotor 32 that uses a permanent magnet. The stator 31 has three windings (coils) 33, 34, and 35 that are Y-connected. A rotating magnetic field is generated by flowing a U-phase, V-phase, and W-phase AC current through the windings 33 to 35 and exciting the cores 36, 37, and 38 in order. The rotor 32 rotates in synchronization with this rotating magnetic field.

  In the example shown in FIG. 2, the number of magnetic poles of the rotor 32 is two. Hereinafter, the rotation position of the S pole indicated by the black circle of the S pole and the N pole of the rotor 32 may be referred to as a magnetic pole position PS of the rotor 32. As shown in FIG. 2B, in this example, the rotor 32 rotates in the right direction, and the cores 36 of the U phase, V phase, and W phase of the stator 31 are 120 in the clockwise direction. It is arranged at an interval.

  The number of magnetic poles of the rotor 32 is not limited to 2, and may be 4, 6 or more multipoles. The rotor 32 may be an outer type or an inner type.

  FIG. 3 shows an example of the functional configuration of the motor control device 21, and FIG. 4 shows the configuration of the motor drive unit 26 and the current detection unit 27 in the motor control device 21, respectively. FIG. 5 shows a current loop R1 by short brake control, and FIG. 6 shows a zero cross point.

  As shown in FIG. 3, the motor control device 21 includes a motor drive unit 26, a current detection unit 27, a rotation speed control unit 22, and a drive control unit 23.

  The motor drive unit 26 is an inverter circuit for driving the rotor 32 by passing a current through the windings 33 to 35 of the brushless motor 3. As shown in FIG. 4, the motor drive unit 26 includes three dual elements 261, 262, and 263, a pre-drive circuit 265, and the like. Each of the dual elements 261, 262, and 263 is a circuit component in which two transistors (for example, field effect transistors: EFT) with uniform characteristics are connected in series and housed in a package.

  The current Iu flowing through the winding 33 is controlled by the transistors Q1 and Q2 of the dual element 261, and the current Iv flowing through the winding 34 is controlled by the transistors Q3 and Q4 of the dual element 262. Then, the current Iw flowing through the winding 35 is controlled by the transistors Q5 and Q6 of the dual element 263.

  In FIG. 4, the pre-drive circuit 265 converts the control signals U +, U−, V +, V−, W +, W− input from the drive control unit 23 into voltage levels suitable for the transistors Q1 to Q6. The converted control signals U +, U−, V +, V−, W +, W− are input to the bases (gates) of the transistors Q1 to Q6.

  The current detection unit 27 includes a U-phase current detection unit 271 and a V-phase current detection unit 272. As a result, the currents Iu and Iv flowing through the windings 33 and 34 are detected. Since Iu + Iv + Iw = 0, the current Iw can be obtained by calculation from the detected currents Iu and Iv.

  Returning to FIG. 3, the rotation speed control unit 22 gives a start command and a stop command to the drive control unit 23 in response to a notification from the main body control unit 20. For example, a start command is given when the image forming apparatus 1 is notified that a print job has been input, and a stop command is given when the completion of the print job is notified. In addition to this, a signal of a duty ratio for pulse width modulation (PWM) corresponding to the rotational speed, a signal designating the rotational direction, a speed command indicating a target value of the rotational speed, and the like are given to the drive control unit 23.

  The drive control unit 23 controls the motor drive unit 26 based on commands and signals input from the rotation speed control unit 22. For example, the start and stop of the motor drive unit 26 are controlled based on the start command or the stop command. The transistors Q1 to Q6 of the motor driving unit 26 are controlled by a pulse width modulation signal (PWM signal), and a rotating magnetic field is generated in the brushless motor 3. Thereby, the start and stop of the brushless motor 3 are controlled.

  Further, when the start command is input when the rotor 32 is in a free-run state due to the stop of the motor drive unit 26 by the input of the stop command, the drive control unit 23 sets the current detected at that time. Based on the magnetic pole position PS and the rotational speed MV of the rotor 32 estimated on the basis, the motor driving unit 26 is restarted so that a rotating magnetic field is generated.

  The drive control unit 23 includes an estimation unit 24 and a short brake control unit 25.

  When the brushless motor 3 is driven by the motor driving unit 26 and in a free-run state after the driving is stopped, the estimating unit 24 is configured to detect the magnetic pole position PS of the rotor 32 based on the detected currents Iu and Iv. The rotational speed MV is estimated.

  For example, when the brushless motor 3 is driven, the estimation unit 24 estimates the magnetic pole position PS and the rotation speed MV by vector calculation or the like. Further, for example, in the free-run state of the brushless motor 3, a zero cross point of a single phase current (for example, Iu) shown in FIG. 6A or a plurality of phase currents Iu, Iv, Based on each zero cross point of Iw, the magnetic pole position PS and the rotational speed MV are estimated.

  As shown in FIG. 6, the zero cross point of the current Iu is a point where the magnitude relationship between the current Iu and the current (Iv + Iw) is reversed. The phase of the current Iu can be determined by the sign of the current Iu between the zero cross point and the next zero cross point. Since there is a correlation between the phase of the current Iu and the magnetic pole position PS, the magnetic pole position PS is known. Further, the rotational speed MV can be calculated from the time between the zero cross point and the next zero cross point. By estimating using the zero-cross points of a plurality of phases, it is possible to improve the accuracy of estimation as compared with the case of using only the zero-cross points of a single phase.

  When the start command is input when the rotor 32 is in a free-run state due to the motor drive unit 26 being stopped by the input of the stop command, the drive control unit 23 detects the currents Iu and Iv detected at that time. Based on the magnetic pole position PS and the rotational speed MV of the rotor 32 estimated based on the above, the motor drive unit 26 is restarted so that a predetermined rotating magnetic field is generated.

  In performing the restart, when the estimated rotational speed MV is equal to or less than a predetermined value, when the rotor 32 is stopped, the motor driving unit is based on the magnetic pole position PS estimated at that time. 26 is controlled.

  The short brake control unit 25 controls the motor driving unit 26 so that when the driving of the brushless motor 3 is stopped, a current loop R1 due to the counter electromotive force generated in the windings 33 and 34 due to the rotation due to inertia is formed. By forming the current loop R1, the current detection unit 27 can detect the currents Iu and Iv.

  That is, as shown in FIG. 5, the transistors Q1, Q3, Q5 for controlling the current flow into the windings 33-35 are all turned off, and the transistor Q2 for controlling the current drawing from the windings 33-35. , Q4, Q6 are all turned on.

  Since a shunt resistor (about 0.1 to 1 ohm) is inserted and connected to the path serving as the current loop R1, the current detection unit 27 performs A / D conversion after amplifying the voltage drop due to the shunt resistor, and performs the current Iu. , Iv.

  In performing the restart, the drive control unit 23 causes the short brake control unit 25 to form a current loop R1 when a stop command is input. Then, the motor drive unit 26 is controlled based on the magnetic pole position PS and the rotational speed MV estimated based on the currents Iu and Iv detected in the current loop R1.

  The drive control unit 23 controls the motor drive unit 26 using, for example, an excitation pattern that is drawn to the next magnetic pole position in the rotation direction when restarting.

  The drive control unit 23 controls the motor drive unit 26 so that a rotating magnetic field is generated according to the input speed command value, and the estimated rotation speed MV is the value at the time of restart when restarting. When the speed command value is exceeded, restart is performed after the estimated rotational speed MV becomes the speed command value at the time of restart.

  Further, when the speed command value at the time of restart is low, the short loop control unit 25 forms the current loop R1 a plurality of times.

  Furthermore, when performing the restart, if the estimated rotational speed MV is less than or equal to a predetermined value, the rotor 32 is moved to a specific magnetic pole position PS by controlling the motor drive unit 26 using a predetermined excitation pattern. Hold control to pull in. And it restarts from the drawn-in specific magnetic pole position PS.

  Note that the hardware configuration of the motor control device 21 is arbitrary. For example, the function of the rotation speed control unit 22 is provided in one CPU (Central Processing Unit) together with the function of the main body control unit 20, and the drive control unit 23 is provided with an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or the like. It can be realized by an integrated circuit. Alternatively, the rotation speed control unit 22 and the drive control unit 23 may be realized by a single integrated circuit.

  Hereinafter, the function of the motor control device 21 will be further described with a focus on processing when activation is requested in a free-run state.

  FIG. 7 shows the flow of motor control processing in the motor control device 21. The motor control device 21 waits for a notification requesting activation from the main body control unit 20 (# 11).

  When a notification requesting activation is input (YES in # 11), motor rotation control is started (# 12). That is, the brushless motor 3 is activated. At this time, initial magnetic pole position estimation processing for estimating the magnetic pole position PS of the rotor 32 in a stopped state is performed. Inductive sensing is used for estimation.

  While the motor drive unit 26 supplies current to the windings 33 to 35 and rotationally drives the rotor 32, speed control is performed so that the rotational speed MV becomes the target value (# 13). When a notification requesting a stop is input from the main body control unit 20 (YES in # 14), the driving of the brushless motor 3 is stopped (# 15).

  Specifically, all the transistors Q1 to Q6 of the motor driving unit 26 are turned off. As a result, the rotor 32 enters a free-run state. The free-run state is a state in which inertia is rotating without depending on the rotating magnetic field. The free-run state includes a state where the current loop R1 is formed by the short brake control, that is, a state where the rotational energy is consumed by heat generation and the inertial rotation is braked.

  If activation (reactivation) is requested during the free-run state (YES in # 16), a reactivation process is executed (# 17). The restart process includes first to fifth examples described later. If the free run ends without requiring a restart (NO in # 16), the process returns to step # 11 to wait for a new start request.

  FIG. 8 shows a first example of the transition of the rotational speed MV from the stop of the drive to the restart, FIG. 9 shows an example of the transition of the current before and after the restart and the excitation pattern after the restart, and FIG. The flow of the first example of the restart process is shown respectively.

  In FIG. 8, a stop command is input from the rotation speed control unit 22 to the drive control unit 23 at time t1, and the drive control unit 23 stops driving by the motor drive unit 26 at time t2. As indicated by a broken line in the figure, free run starts from time t2, and the rotational speed MV gradually decreases.

  A start command (restart command) is input to the drive control unit 23 at time t3 within a period during which the free run continues. When the activation command is input, the drive control unit 23 starts estimating the magnetic pole position PS and the rotation speed MV. At time t4, when the magnetic pole position PS and the rotational speed MV are estimated (detected), the driving of the brushless motor 3 is resumed using the excitation pattern drawn into the next magnetic pole position in the rotation direction.

  In other words, it is assumed that the currents Iu and Iv having the phases shown in FIG. 9A are detected in the process of estimating the magnetic pole position PS, for example. The magnetic pole position PS at time t4 can be determined from the phases of the currents Iu and Iv. In this case, for example, as shown in the left part of FIG. 9C, the magnetic pole position PS at time t4 is a position of 180 °.

  The drive control unit 23 controls the motor drive unit 26 by using an excitation pattern (current pattern) for rotational driving so that the rotation at that time is smoothly continued corresponding to the detected magnetic pole position PS.

  In other words, the motor drive unit 26 causes a current to flow through the windings 33 to 35 so as to obtain, for example, an excitation pattern for rotation drive illustrated in FIG. 9B from time t4. As a result, the rotor 32 continues to rotate smoothly from time t4, and the rotational speed is increased to reach the target speed. In this way, the brushless motor 3 is restarted.

  As shown in FIG. 8, according to the present embodiment, since the restart is performed at time t4 before the free run is stopped, the response time T1 from the time t3 of the start command to the time t4 of restart is set as the conventional response time. It can be significantly shortened than T1z.

  Conventionally, as indicated by a one-dot chain line in FIG. 8, the magnetic pole position PS is estimated by inductive sensing from time t6 later than time t5 when the free run actually stops, and restarted at time t7 when the estimation is finished. . For this reason, the response time T1z is long. The period from time t5 to time t6 is a margin set in consideration of the increase / decrease of the free run time depending on the load.

  As shown in FIG. 10, in the first example of the restart process, the current loop R1 is formed by the short brake control (# 101), and the currents Iu and Iv flowing through the current loop R1 are detected (# 102). The magnetic pole position PS and the rotational speed MV are estimated based on the detected currents Iu and Iv (# 103), and the brushless motor 3 is restarted (# 104).

  FIG. 11 shows a second example of the transition of the rotational speed MV from the stop of the drive to the restart, and FIG. 12 shows a flow of the second example of the restart process.

  At time t2, driving stops and free run begins. An activation command is input at time t31 within a period during which the free run continues. The drive control unit 23 estimates the magnetic pole position PS and the rotation speed MV. Then, the estimated rotational speed MV is compared with a predetermined value Va. The predetermined value Va is, for example, a sufficiently large current Iu. It can be set to a value at which Iv cannot be obtained.

  When the estimated rotation speed MV is equal to or less than the predetermined value Va, the arrival of time t51 when the rotor 32 is stopped is awaited. Whether the rotor 32 has stopped is determined whether the elapsed time from the time t2 has exceeded a predetermined time, or the current Iu. The determination can be made based on whether the maximum value of Iv is equal to or less than a certain value.

  When the time t51 arrives, the magnetic pole position PS is estimated by inductive sensing, and the driving of the brassless motor 3 is resumed at the time t71 when the estimation is finished.

  Also in the second example, when the rotational speed MV is equal to or higher than the predetermined value Va, the restart is accelerated before the free run is stopped, so that the restart is accelerated.

  When the rotational speed MV is equal to or less than the predetermined value Va, the point of restarting after waiting for the free run is the same as in the conventional case, but unlike the conventional case, the rotational speed MV is estimated during the free run. The time t51 when the free run ends can be estimated with a certain degree of accuracy. In other words, unlike the conventional case, there is no need to increase the margin. Therefore, the response time T11 from the start command time t31 to the restart time t71 can be made shorter than the conventional response time T1z (see FIG. 8).

  As shown in FIG. 12, in the second example of the restart process, similarly to the first example, the current loop R1 is formed by the short brake control (# 201), and the currents Iu and Iv flowing through the current loop R1 are detected. (# 202). Then, the magnetic pole position PS and the rotational speed MV are estimated based on the detected currents Iu and Iv (# 203).

  If the estimated rotational speed MV is not less than or equal to the predetermined value Va (NO in # 204), the brushless motor 3 is restarted (# 207).

  On the other hand, if the rotational speed MV is equal to or lower than the predetermined value Va (YES in # 204), the process waits for the rotor 32 to stop (# 205), and estimates the magnetic pole position PS after the stop (# 206). Thereafter, the brushless motor 3 is restarted (# 207).

  FIG. 13 shows a third example of the transition of the rotational speed MV from the stop of the drive to the restart, and FIG. 14 shows the flow of the third example of the restart process.

  An activation command is input at time t32 within a period during which the free run continues. The drive control unit 23 estimates the magnetic pole position PS and the rotation speed MV. Then, the estimated rotational speed MV and the target speed Vx are compared.

  The target speed Vx is a speed command value input from the rotation speed control unit 22. For example, when printing in the high image quality mode, the conveyance of the paper 9 may be made slower than when printing in the normal mode. In this case, a speed smaller than normal is given as the target speed Vx.

  When the estimated rotational speed MV exceeds the target speed (speed command value) Vx at the time of restart, from time t42 when the estimated rotational speed MV becomes the target speed Vx at the time of restart. Perform a restart.

  Since the restart is performed at time t42 earlier than the time t52 at which the free run is stopped, the response time T12 from the start command time t32 to the restart time t42 can be significantly shortened from the conventional response time T1z. .

  As shown in FIG. 14, in the third example of the restart process, the current loop R1 is formed by the short brake control (# 301), and the currents Iu and Iv flowing through the current loop R1 are detected (# 302). Then, the magnetic pole position PS and the rotational speed MV are estimated based on the detected currents Iu and Iv (# 303).

  If the estimated rotational speed MV exceeds the target speed Vx (YES in # 304), the process returns to step # 303 to estimate the magnetic pole position PS and the rotational speed MV again.

  On the other hand, when the rotational speed MV does not exceed the target speed Vx (NO in # 304), the brushless motor 3 is restarted (# 305).

  FIG. 15 shows a fourth example of the transition of the rotational speed MV from the stop of the drive to the restart, and FIG. 16 shows a flow of the fourth example of the restart process.

  An activation command is input at time t33 within a period during which the free run continues. The drive control unit 23 estimates the magnetic pole position PS and the rotation speed MV. Then, the estimated rotational speed MV and the target speed Vx are compared.

  If the estimated rotational speed MV exceeds the target speed Vx at the time of restart, the short brake control is interrupted and the current loop R1 is released. This release state is maintained over the period Tb. The length of the period Tb is set so as to secure a period Ta for once again estimating the magnetic pole position PS and the rotational speed MV until the rotational speed MV reaches the target speed Vx.

  After maintaining the release state over the period Tb, short brake control is performed again to estimate the magnetic pole position PS and the rotational speed MV. And it restarts from the time t43 which is the timing when the estimated rotational speed MV becomes the target speed Vx at the time of restart.

  That is, in the fourth example, the formation of the current loop R1 by the short brake control unit 25 is divided into two, and the period in which the current loop R1 is formed is shortened by providing the period Tb in the release state. According to this, the influence of heat generation due to the current flowing through the current loop R1 can be reduced.

  As in the third example, the restart is performed at a time t43 earlier than the time t53 at which the free run is stopped. Therefore, the response time T13 from the start command time t33 to the restart time t43 is set to the conventional response time T1z. Can be significantly shortened.

  As shown in FIG. 16, in the fourth example of the restart process, the current loop R1 is formed by the short brake control (# 401), and the currents Iu and Iv flowing through the current loop R1 are detected (# 402). Then, the magnetic pole position PS and the rotational speed MV are estimated based on the detected currents Iu and Iv (# 403).

  If the estimated rotational speed MV exceeds the target speed Vx (YES in # 404), deceleration estimation that determines the length of the period Tb is performed (# 406), and the short brake control is released (# 407). The process waits for a predetermined time to end the period Tb (# 408), and when the predetermined time arrives (YES in # 408), the process returns to step # 401 to estimate the magnetic pole position PS and the rotational speed MV again.

  On the other hand, when the rotational speed MV does not exceed the target speed Vx (NO in # 404), the brushless motor 3 is restarted (# 405).

  FIG. 17 shows a fifth example of the transition of the rotational speed MV from the stop of the drive to the restart, and FIG. 18 shows a flow of the fifth example of the restart process.

  An activation command is input at time t34 within a period during which the free run continues. The drive control unit 23 estimates the magnetic pole position PS and the rotation speed MV. Then, the estimated rotational speed MV is compared with a predetermined value Vb. The predetermined value Vb can be a value that can quickly hold the magnetic pole position PS.

  When the estimated rotation speed MV is equal to or lower than the predetermined value Vb, hold control is performed. The hold control is a process of pulling the rotor 32 to a specific magnetic pole position PS by controlling the motor driving unit 26 using a predetermined excitation pattern for holding.

  As shown in FIG. 17, restart is performed from time t44 when the holding of the magnetic pole position PS is completed. Since the magnetic pole position PS is determined by the hold control, it is not necessary to estimate the magnetic pole position PS again by inductive sensing. Therefore, the response time T14 from the start command time t34 to the restart time t44 can be made shorter than the conventional response time T1z.

  As shown in FIG. 18, in the fifth example of the restart process, the current loop R1 is formed by the short brake control (# 501), and the currents Iu and Iv flowing through the current loop R1 are detected (# 502). Then, the magnetic pole position PS and the rotation speed MV are estimated based on the detected currents Iu and Iv (# 503).

  If the estimated rotational speed MV is not less than or equal to the predetermined value Vb (NO in # 504), the brushless motor 3 is restarted (# 506).

  On the other hand, if the rotational speed MV is equal to or lower than the predetermined value Vb (YES in # 504), hold control is performed (# 505), thereby forcibly positioning the rotor 32. Thereafter, the brushless motor 3 is restarted (# 506).

  According to the above embodiment, the response time T1, T11, T12, T13, T14 from the command to the restart when the restart is instructed in the free-run state can be shortened.

  In the embodiment described above, when a start command is issued when the brushless motor 3 is in the free-run state, the short brake control is performed to form the current loop R1, thereby detecting the currents Iu and Iv. Therefore, the rotational speed MV and the magnetic pole position PS of the brushless motor 3 at that time can be easily detected, and the responsiveness is good and smooth restart can be performed. In this regard, in Patent Document 1, since the induced voltage is detected by inputting the three-phase neutral point side potential and the non-neutral point side potential to the differential amplifier, once the detection is stopped. The neutral point becomes high impedance and cannot be determined, and the magnetic pole position cannot be detected.

  In the embodiment described above, the motor control device 21 can be applied to control of a sensorless permanent magnet synchronous motor mounted on a device other than the image forming apparatus 1.

  In addition, the configuration of the whole or each part of the motor control device 21, the contents of processing, the order or timing, the predetermined values Va and Vb, the structure of the brushless motor 3, and the like can be appropriately changed in accordance with the spirit of the present invention.

21 Motor controller (permanent magnet synchronous motor controller)
23 Drive control unit (control unit)
24 Estimating unit 25 Short brake control unit 26 Motor driving unit (driving unit)
27 Current detector 32 Rotors 33, 34, 35 Winding wires Iu, Iv, Iw Current MV Rotational speed PS Magnetic pole position R1 Current loop Va, Vb Predetermined value Vx Target speed (speed command value)

Claims (11)

A control device for a permanent magnet synchronous motor in which a rotor using a permanent magnet is rotated by a rotating magnetic field caused by a current flowing in the winding,
A driving unit for driving the rotor by passing a current through the winding;
A current detector for detecting a current flowing in the winding;
An estimation unit that estimates the magnetic pole position and rotation speed of the rotor based on the detected current;
The drive unit is controlled to generate the rotating magnetic field based on the magnetic pole position and the rotation speed estimated by the estimation unit, and the drive unit is started and stopped based on the input start command and stop command. A control unit for controlling
When the start command is input when the rotor is in a free-run state due to the drive unit being stopped by the input of the stop command, the control unit is estimated based on the current detected at that time Restarting the drive unit to generate the rotating magnetic field based on the magnetic pole position and the rotation speed of the rotor
A control device for a permanent magnet synchronous motor. When the estimated rotational speed is less than or equal to a predetermined value in performing the restart, the control unit, when the rotor is stopped, the magnetic pole position estimated at that time Controlling the drive unit based on
The controller for a permanent magnet synchronous motor according to claim 1. A short brake control unit that controls the drive unit so as to form a current loop due to a counter electromotive force generated in the winding;
In performing the restart, the control unit forms the current loop by the short brake control unit when the stop command is input, and the magnetic pole estimated based on the current detected in the current loop Controlling the driving unit based on the position and the rotation speed;
The controller for a permanent magnet synchronous motor according to claim 1 or 2. The estimation unit estimates the magnetic pole position and the rotation speed of the rotor based on the detected zero cross point of the current.
The control device for a permanent magnet synchronous motor according to any one of claims 1 to 3. The estimation unit estimates the magnetic pole position and the rotation speed of the rotor based on the zero cross points for a plurality of phases.
The controller for a permanent magnet synchronous motor according to claim 4. The control unit, when performing the restart, controls the drive unit using an excitation pattern that is pulled into the next magnetic pole position in the rotation direction.
The control device for a permanent magnet synchronous motor according to any one of claims 1 to 5. The control unit controls the driving unit so that the rotating magnetic field is generated according to the input speed command value, and the estimated rotational speed is the value at the time of restarting when performing the restarting. In a case where the speed command value is exceeded, the restart is performed after the estimated rotational speed becomes the speed command value at the time of restart,
The control device for a permanent magnet synchronous motor according to claim 3. When the speed command value at the time of restart is low, the current loop is formed by the short brake control unit a plurality of times.
The controller for a permanent magnet synchronous motor according to claim 7. In performing the restart, when the estimated rotation speed is equal to or less than a predetermined value, the control unit controls the drive unit using a predetermined excitation pattern to identify the rotor. Hold control that pulls in the magnetic pole position, and restarts from the specific magnetic pole position that is pulled in,
The control device for a permanent magnet synchronous motor according to any one of claims 1 to 5. A method for controlling a permanent magnet synchronous motor in which a rotor using a permanent magnet is rotated by a rotating magnetic field generated by a current flowing through a winding,
When the drive of the rotor is stopped by the input of a stop command and the start command is input when the rotor is in a free-run state, the current flowing through the shoreline is detected, and the detected current The rotor magnetic pole position and the rotational speed are estimated based on the current, and the rotor is driven by passing a current through the winding so that the rotating magnetic field is generated based on the estimated magnetic pole position and the rotational speed. ,
A control method of a permanent magnet synchronous motor, characterized in that. When detecting the current flowing through the winding, a current loop is formed by a counter electromotive force generated in the winding and a short brake is applied, and the magnetic pole position of the rotor and the rotor based on the current detected in the current loop Estimate the rotational speed,
The method for controlling a permanent magnet synchronous motor according to claim 10.

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