JP2014233182A - Controller of brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of a brushless motor in which responsiveness in a feedback control is improved, and vibration of the motor is suppressed in the region where input voltage of the motor is high voltage.SOLUTION: A controller of a brushless motor is provided with a feedback gain setting unit 1008 which, upon setting a feedback control amount, sets a feedback gain coefficient of the motor according to rotational speed of a motor. The feedback gain setting unit 1008 varies weighting of the feedback gain coefficient according to input voltage of the motor.

Description

  The present invention relates to a brushless motor control device.

  Conventionally, a brushless motor is used as a drive source to control the rotational speed of a gear pump (trochoid type) (see, for example, Patent Document 1).

  In such a brushless motor control device used for a pump or the like, a target rotational speed is given, and the rotational speed is controlled by feedback control so that the actual rotational speed converges to the target rotational speed. ing.

  As a feedback control method, PID control is widely used.

  FIG. 7 is a diagram showing a basic expression of PID control, in which a proportional amount that gives a correction amount proportional to the current deviation e, an integral that gives a correction amount proportional to the cumulative value of past deviations, and the deviation e It is a combination of the three components, that is, whether it is increasing or decreasing, and a differential component that produces a correction amount proportional to the magnitude of the tendency.

  Generally, it is said that when the coefficient of the feedback gain Kp is increased, the control amount of the motor is increased and the response time is shortened.

JP 2008-086117 A

  However, in such a conventional case, when the input voltage of the motor fluctuates, the feedback control response becomes unstable, and there is a problem that a desired motor rotation speed cannot be obtained.

  In particular, when the feedback gain coefficient is increased while the motor input voltage is high, motor vibration tends to increase.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an oil pump control device that improves convergence to a target rotational speed regardless of fluctuations in the input voltage of the motor. To do.

  In order to solve the above-mentioned problem, in the brushless motor control apparatus according to claim 1 of the present invention, the motor control amount is adjusted so that the rotational speed of the rotationally driven motor converges to the target rotational speed. In the brushless motor control apparatus that performs feedback control, the coefficient of the feedback gain in the PID control value calculated by the feedback control is varied according to the input voltage of the motor.

  Further, in the brushless motor control device according to claim 2, the brushless motor control device includes a period from when the motor starts from a rotation stop state until the actual rotation speed of the motor converges to a target rotation speed. The variable feedback gain coefficient is fixed to a value lower than the normal control value, and the feedback gain coefficient is input to the motor when the actual rotational speed of the motor converges to the target rotational speed at a predetermined rotational speed or higher. It was decided to vary according to the voltage.

  In the brushless motor control device according to claim 3, the brushless motor control device counts the actual rotation speed of the motor and the elapse of a predetermined time when the actual rotation speed of the motor is reached. The coefficient of the feedback gain was made variable.

  According to a fourth aspect of the present invention, there is provided the brushless motor control device, wherein the brushless motor control device is configured to adjust the feedback gain that is variable when the target rotational speed of the motor shifts to feedback control in a direction that reduces the actual rotational speed. The coefficient was fixed to a value lower than the normal control value.

  Furthermore, in the brushless motor control device according to the fifth aspect, the brushless motor control device is used for driving an electric liquid pump.

  As described above, in the brushless motor control apparatus according to the first aspect of the present invention, the convergence of the actual rotational speed to the target rotational speed is achieved by varying the feedback gain coefficient in accordance with the output voltage of the motor. On the other hand, it is possible to suppress the occurrence of vibration in the high rotation range and to stabilize the characteristics of the rotational speed control.

  In the brushless motor control device according to the second aspect, the feedback gain at the time of starting is suppressed to a value smaller than that at the normal time, so that the feedback gain coefficient at the time of starting from the rotation stop state is excessive. It is possible to reduce the occurrence of tone, and to improve the responsiveness and rotational speed control characteristics during rotational speed control at startup.

  In the brushless motor control device according to claim 3, the feedback gain coefficient is varied by counting the actual rotational speed of the motor and the lapse of a predetermined time when the actual rotational speed of the motor is reached. As a result, convergence to the target rotation speed in the high rotation range of the motor can be improved and control instability associated with inadvertent feedback gain switching can be suppressed.

  In the brushless motor control apparatus according to the fourth aspect, the convergence is improved when the deviation value between the target rotational speed and the actual rotational speed is large, while the target rotational speed is a deviation lower than the actual rotational speed. In some cases, the power consumption can be reduced by reducing the feedback gain.

  In addition, in the brushless motor control device according to claim 5, the brushless motor control device is used for driving an electric liquid pump, so that a change in fluid characteristics of the pump, for example, the temperature of the working fluid, Even if there is a mechanical variation such as viscosity or clearance near the pump chamber and fluctuations occur in the control of the flow characteristics, an appropriate feedback gain coefficient is determined by determining the numerical value in accordance with the fluid or mechanical characteristics. The efficiency can be adjusted by a simple method.

It is sectional drawing of the brushless motor type electric pump which shows one embodiment of this invention. It is a disassembled perspective view which shows the embodiment. It is a block diagram for showing operation of the brushless motor in the embodiment. It is a flowchart which shows the operation | movement which concerns on the feedback control of the brushless motor in the embodiment. It is explanatory drawing of the table regarding the coefficient setting of the feedback gain of the brushless motor in the embodiment. 6 is a timing chart showing changes in the target rotational speed, actual rotational speed, and feedback gain of the motor in the same embodiment from when the motor is started. It is a figure which shows the basic formula of PID control.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 and 2 are views showing an electric oil pump 1 whose rotational speed is controlled by a brushless motor control device according to the present embodiment. The electric gear pump 1 includes a motor 2 and a motor. The oil pump 3 driven by 2 is provided. As a result, the oil for cooling the motor is used for supplying, or used for the purpose of maintaining the hydraulic pressure which is attached to an automatic transmission such as an AT or CVT of an automobile and decreases at the time of idling stop at a predetermined pressure.

  That is, a hydraulic circuit is formed in the automatic transmission 4, and a hydraulic path 12 for forming the hydraulic circuit is formed in the casing 11 of the automatic transmission 4. A mounting hole 14 for mounting the electric gear pump 1 is opened on the outer surface 13 of the casing 11 so that the front end portion of the electric gear pump 1 is inserted into the mounting hole 14. It is configured.

  Oil 21 used for control of the automatic transmission 4 circulates in the hydraulic path 12, and a back surface 22 of the mounting hole 14 has a communication path 23 communicating with an oil storage portion (not shown) and an additional pressure. An output path 24 for outputting the pressurized oil 21 is opened.

  FIG. 2 is an exploded perspective view showing the electric gear pump 1. The electric gear pump 1 includes a pump component 31 constituting the trochoid oil pump and a motor for driving the pump component 31. A configuration unit 32 and a motor drive control unit 33 for controlling the motor configuration unit 32 are provided. The pump component 31, the motor component 32, and the motor drive controller 33 are arranged in the extending direction of the rotating shaft 34 that constitutes the motor component 32, and extend from the motor component 32. As shown in FIG. 1, the rotating shaft 34 is configured to be connected to the pump component 31 in the assembled state.

  The electric gear pump 1 includes a cylindrical case 41 constituting an outer peripheral portion, and the pump component 31 and the motor component 32 are fitted inside the case 41. In this internal fitting state, the outer peripheral surface of the pump component 31 and the outer peripheral surface of the motor component 32 are configured to contact the inner surface 42 of the case 41, and in this surface contact state, the pump The component 31 and the motor component 32 are configured to be positioned.

  A case flange portion 51 that extends outward is integrally formed at the base end of the case 41, and the electric gear pump 1 includes the case flange portion 51 as shown in FIGS. 1 and 2. The distal end side constitutes an insertion region to be inserted into the mounting hole 14 provided in the casing 11, and the proximal end side from the case flange portion 51 is configured to form a protruding region protruding from the casing 11. Yes.

  In a state where the electric gear pump 1 is mounted in the mounting hole 14, the case flange portion 51 is configured to contact the outer surface 13 of the casing 11, and the case flange portion 51 causes the electric motor pump 1 to be in contact with the outer surface 13. The gear pump 1 is configured to be fixed to the casing 11.

  The pump component 31 and the motor component 32 are arranged on the distal end side of the case 41 with respect to the case flange portion 51 constituting the insertion region, and the mounting state shown in FIG. , The front end surface of the pump component 31 protruding from the case 41 is configured to face the back surface 22 of the mounting hole 14.

  As shown in FIGS. 1 and 2, the pump component 31 includes a pump base 71 that forms a distal end side, and a pump housing 72 that is disposed on the proximal end side of the pump base 71, An O-ring 73 is disposed between the pump housing 72 and the pump base 71. As shown in FIG. 1, a circular projecting portion 74 that is inserted into the circular hole of the case 41 and protrudes to the outside is integrally formed on the front end surface of the pump base 71. The protrusion 74 is configured such that the outer periphery of the protrusion 74 is supported by the bent portion 61 at the tip of the case 41 so that the protrusion 74 is prevented from coming off toward the tip.

  One end portion of a pin 91 is inserted into the base end surface of the pump base 71, and the other end portion of the pin 91 is placed on the front end surface of the pump housing 72 arranged to face the pump base 71. Has been inserted. Accordingly, the pump housing 72 is positioned with respect to the pump base 71. In this state, the pump housing 72 is press-fitted and fixed to the case 41, and the outer peripheral surface of the pump base 71 is The case 41 is fixed in close contact with the inner surface 42.

  As shown in FIG. 1, the central portion of the pump housing 72 is immersed, and a rotor accommodating portion 101 is formed between the pump housing 72 and the pump base 71. A pump rotor outer 102 is rotatably accommodated in the rotor accommodating portion 101, and a pump rotor inner 103 is rotatably accommodated in the pump rotor outer 102.

  A suction port 111 and a discharge port 112 provided in the pump base 71 communicate with the rotor accommodating portion 101, and both ports 111, 112 are opened at the end surface of the projecting portion 74 of the pump base 71. Is configured to do.

  The suction port 111 is configured to be connected to the communication path 23 provided in the inner surface 22 of the mounting hole 14 in a state where the electric gear pump 1 is mounted in the mounting hole 14. The discharge port 112 is configured to be connected to the output path 24 through an O-ring 121.

  As a result, the pump rotor outer 102 rotates as the pump rotor inner 103 rotates, so that the oil sucked from the communication passage 23 through the suction port 111 is pressurized, and the discharge port 112 A trochoid pump that outputs to the output path 24 is formed.

  On the base end side of the trochoid pump, as shown in FIG. 1, a DC brushless motor constituted by the motor constituting portion 32 is disposed. The motor includes a motor case 201 that forms an outer peripheral portion, and the outer peripheral surface of the motor case 201 is fixed in a state of being in close contact with the inner side surface 42 of the case 41.

  A coil 212 around which a motor winding 211 is wound is fitted inside the motor case 201, and a stator 213 excited by the coil is held in the coil 212. A motor rotor core 214 is rotatably accommodated inside the stator 213, and a magnet 215 is provided on the outer peripheral surface of the motor rotor core 214. The rotation shaft 34 is inserted into the motor rotor core 214, and the rotation shaft 34 is fixed in a state of penetrating the motor rotor core 214.

  The other end portion of the rotating shaft 34 extends toward the front end side, and the rotating shaft 34 is inserted through the center hole 222 of the pump housing 72 through the oil seal 221 to be inside the rotor accommodating portion 101. It is comprised so that it may protrude. A flat surface 223 is formed on the peripheral surface of the rotating shaft 34 protruding from the rotor accommodating portion 101, and a rotor connecting portion 224 having a D-shaped cross section is formed. This rotor connecting portion 224 is inserted into the D-shaped hole 225 of the pump rotor inner 103 accommodated in the rotor accommodating portion 101, and then freely rotatable into the counterbore hole 227 of the pump base 71 via the tip side bearing. Supported in a contained state.

  The motor drive control unit 33 is disposed on the base end side of the motor configured by the motor configuration unit 32, and the motor drive control unit 33 is connected to the base end portion of the motor configuration unit 32. Insulator 301 is provided (see FIG. 2).

  The insulator 301 is made of synthetic resin, and is integrally formed with a motor connecting portion 311 that is inserted into the base end portion of the motor case 201 of the motor constituting portion 32 and connected in an internally fitted state. One end portion of the rotating shaft 34 is rotatably supported by the motor connecting portion 311 via a base end side bearing 314.

  Bus bars 321,... For relaying energization to the motor winding 211 are insert-molded in the motor connection portion 311, and the bus bars 321,. The motor winding 211 is electrically connected.

  In addition, a connector portion 322 that protrudes upward and has a harness connection hole 324 opened to the side is integrally formed on the side edge portion of the motor connection portion 311, and is formed on the back surface of the connector portion 322. The connection terminals 323 and 323 that are electrically connected to the harness are insert-molded.

  A plurality of support columns 333,... Are erected on the end surface of the motor connection unit 311, and a control board 334 is supported by the support columns 333,. An electronic circuit is formed on the control board 334, and the bus bar 321 is based on a signal input from the connector unit 322 in a state where the harness extended from an external device is connected to the connector unit 322. ,... Is configured to control the motor drive by controlling the output signal to.

  The motor drive control unit 33 includes a container-like controller cover 331 attached to the base end portion of the case 41, and the control board 334 supported by the motor connection unit 311 is configured by the controller cover 331. It is comprised so that it may be covered with.

  The controller cover 331 is made of aluminum, and a plurality of cooling fins 341,... For releasing heat generated inside to the outside are provided on the outer surface of the controller cover 331.

  An engagement recess 351 is formed in the base end portion of the connector portion 322 of the insulator 301, and the end portion side of the engagement recess 351 is slightly lower than the general portion of the connector portion 322 base end. A step portion 352 is formed. An extension piece 353 on one end side of the controller cover 331 that overlaps with the base end portion of the connector portion 322 is configured to extend on the stepped portion 352, and at the tip of the extension piece 353. The engaging convex portion 354 that engages with the engaging concave portion 351 is bent.

  As a result, the meshing structure in which the engagement convex portion 354 of the controller cover 331 is engaged with the engagement concave portion 351 of the connector portion 322 is engaged with the engagement convex portion 354 and the engagement concave portion. 351, a sealant is applied to a joint portion between the engagement recess 351 and the engagement projection 354 so that the engagement projection 354 and the engagement recess 351 are engaged with each other at the time of assembly. It is configured.

  Further, on the other end side of the controller cover 331, a cover flange portion 371 extending in a lateral direction from a portion externally fitted to the motor case 201 in a mounted state corresponds to the case flange portion 51. The cover flange portion 371 and the case flange portion 51 are in contact with each other and the outer fitting portion that is externally fitted to the motor case 201 is applied with a sealant during assembly. ing.

  A bolt insertion hole 381 is formed in the cover flange portion 371 and the case flange portion 51 that is in contact with the cover flange portion 371, and a collar 382 is fitted in the bolt insertion hole 381.

  As a result, as shown in FIG. 1, the bolt 391 inserted through the collar 382 in the bolt insertion hole 381 in a state where the case flange portion 51 is in contact with the outer surface 13 of the casing 11 at the time of mounting. The electric gear pump 1 can be fixed to the casing 11 by being screwed into a screw hole 392 formed in the casing 11.

  FIG. 3 is a block diagram showing a brushless motor control device 1001 for driving the electric gear pump 1.

  The brushless motor control device 1001 includes a target rotational speed setting unit 1002 for setting a target rotational speed of the motor, a target motor rotational speed set by the target rotational speed setting unit, and an actual motor rotational speed. And a feedback control amount calculation unit 1003 for setting the motor feedback control amount based on the deviation of the motor and the rotational position of the motor, and the motor control amount such as the motor voltage and current set by the feedback control amount calculation unit as U An inverter unit 1004 for outputting to the V / W three-phase motor winding 211 is provided.

  On the other hand, in the brushless motor according to the present embodiment, the back electromotive force generated in each of the three phases of the motor winding is detected by the voltage detector 1005, and the rotational position and rotational speed of the motor are determined based on the back electromotive voltage of each phase. Sensorless control to estimate is used.

  Specifically, the PN input voltage of the inverter is a motor voltage.

  That is, a rotation position estimation unit 1006 that estimates the rotation position of the motor based on the input of the back electromotive voltage and an actual rotation speed estimation unit 1007 that estimates the motor rotation speed based on the estimated rotation position of the motor are provided. Based on the estimated rotation speed and rotation position, the control amount calculation in the feedback control amount calculation unit 1003 is performed.

  Similarly, a motor voltage is detected by a voltage detection unit 1005 from the three-phase motor winding 211 of U, V, and W.

  In setting the feedback control amount, a feedback gain setting unit 1008 is provided for setting a coefficient of the feedback gain of the motor in accordance with the rotation speed of the motor and the motor voltage. The feedback gain setting unit 1008 weights the feedback gain coefficient mainly by the motor voltage during steady operation of the motor. In addition, the feedback gain setting unit 1008 is in a state immediately after starting or a constant steady state after starting. A function is also provided for determining whether there is a weight and weighting the coefficient of the feedback gain.

  FIG. 4 is a flowchart showing the operation of the brushless motor control device 1001, and the operation related to the setting of the feedback gain coefficient in accordance with conditions such as the rotational speed of the motor and the elapsed time after reaching a predetermined rotational speed after starting. It is shown.

  First, when starting from the motor stop state, the start is determined (S1), and when the start is determined, the start flag Fst = 1 is set (S2). If it is determined that it is not at the time of startup, this flow is skipped and the process proceeds to the next.

  Next, the target rotational speed Nt is set based on various operating conditions (S3), and the actual rotational speed N is estimated based on the motor back electromotive current and the like (S4).

  Here, the actual rotational speed N and the threshold value Nsl for switching the feedback gain coefficient are compared (S5). If the actual rotational speed N is equal to or lower than the threshold value Nsl, the feedback gain coefficient is set to Kp = Kp1. Set (S6). The coefficient Kp1 is set to a value smaller than a normal coefficient Kp2 described later.

  When the feedback gain coefficient Kp is set, based on the deviation e between the target rotational speed Nt and the actual rotational speed N and the coefficient Kp, the feedback control amount is calculated by the basic equation of PID control shown in FIG. S7), current and voltage for motor control are output to the coil 211 (S8).

  On the other hand, if the actual rotational speed N exceeds the threshold Nsl in step S5, it is determined whether or not the activation flag Fst is set (S9). If Fst = 1 is set, the timer T is counted. Start (S10).

  Next, it is determined whether or not the deviation e between the target rotational speed Nt and the actual rotational speed N is e = 0, that is, in a converged state (S11). If e = 0 is not satisfied, the feedback gain coefficient is set to Kp = Kp1 (S6). If e = 0, it is determined that the steady state is being reached, and the elapsed time of the timer T is determined.

  When the start flag Fst = 1 is set and the actual rotation speed N subsequently increases and exceeds the threshold value Nsl, it is determined whether the elapsed time of the timer T has exceeded a predetermined value Tsl. (S12) If the predetermined value Tsl has not elapsed, the feedback gain coefficient is set to Kp = Kp1 (S6).

  On the other hand, when the elapsed time of the timer T exceeds the predetermined value Tsl, the activation flag Fst is reset to Fst = 0 (S13), and the count of the timer T is reset (S14). The feedback gain at this time is given the normal coefficient Kp2 described above (S15).

  Since the feedback gain coefficient Kp2 at this time is determined by the motor input voltage V, the input of the motor voltage is received (S16), and the feedback gain coefficient Kp2 is determined by the motor input voltage V as shown in FIG. A numerical value is referred to by a simple table T. (S17)

  At this time, the feedback gain coefficient Kp2 is increased in a region where the input voltage V of the motor is small to ensure responsiveness, while the feedback gain coefficient Kp2 is decreased as the motor input voltage V decreases. The occurrence of vibration of the motor is suppressed by reducing. In this embodiment, the minimum value of the feedback gain coefficient Kp2 is set to the same value as the feedback gain coefficient Kp1 at the time of startup.

  When the feedback gain coefficient Kp2 is determined, calculation of the coefficient feedback control amount (S7) and output of motor control current and voltage (S8) are performed.

  In this embodiment, in the setting determination (S9) of the start flag Fst = 1, when the start flag Fst = 0, the deviation e between the target rotational speed Nt and the actual rotational speed N is positive. It is determined whether the value is a negative value or a negative value, and the feedback gain coefficient Kp is varied (S18). In this case, when the deviation e ≧ 0, that is, when the control direction is in the increasing direction and the constant rotational speed is maintained, the feedback gain is given the normal coefficient Kp2 (S15), and the deviation e < When 0, that is, when the control direction is in the decreasing direction, the feedback gain coefficient is given by Kp = Kp1. (S6).

  FIG. 5 is a timing chart showing time-series numerical changes of the target rotational speed Nt, the actual rotational speed N, and the feedback gain coefficient Kp from the time of starting the motor.

  At the time of start-up from the motor rotation stop, the feedback gain coefficient is always given as Kp = Kp1 while it is increased to the target rotation speed Nt2 in the high rotation range, and feedback control is performed to prevent motor step-out. Yes.

  On the other hand, when the actual rotational speed N exceeds the threshold value Nsl for feedback gain coefficient switching determination, the elapsed time is counted, and the state where the actual rotational speed N converges to the target rotational speed Nt is continued for a certain period. The feedback gain coefficient is in a normal control state with Kp = Kp2, and feedback control is performed with an emphasis on responsiveness.

  Thereafter, when the target rotational speed Nt becomes equal to or less than the threshold value Nsl and converges in the direction in which the actual rotational speed N decreases, the power consumption of the motor is suppressed by setting the feedback gain coefficient to Kp = Kp1 again. When the control is shifted from the low rotation range where the actual rotation speed N of the motor is equal to or less than the threshold value Nsl to the direction exceeding the threshold value Nsl, the feedback gain coefficient immediately becomes Kp = Kp2, while the target rotation speed Nt is If the motor is 0 and the motor is stopped, the feedback gain coefficient setting Kp = Kp1 at the time of startup is returned to the same as at the beginning.

  Since the value of the feedback gain coefficient Kp2 at this time varies depending on the motor input voltage V as described above, the value of Kp2 is limited in a high voltage region where the motor vibration is likely to occur. It is possible to optimize the feedback control of the motor.

  The feedback gain coefficients Kp1 and Kp2 can be set in consideration of individual variations such as the load on the output side of the motor, that is, the flow characteristics of the electric pump and the clearance of the gear pump in this embodiment. Therefore, the desired feedback control amount can be optimized regardless of the form of the load.

  In particular, in the present embodiment, a low feedback gain coefficient Kp1 is used at the time of feedback control of the motor rotation speed at start-up, while a high feedback gain coefficient Kp2 is used in a high rotation range of the motor. While the former performs feedback control to prevent step-out, the latter allows feedback control with an emphasis on responsiveness.

  Further, even in the feedback control in the deceleration direction such that the target rotational speed Nt is lower than the actual rotational speed N, the low feedback gain coefficient Kp1 is used, so that the power consumption of the motor can be reduced.

  In the present invention, an electric gear pump is used as a load of the motor. However, the present invention is not limited to this, and another rotary pump may be used or a load other than the pump may be used.

  Further, in this embodiment, when the motor rotation speed reaches the threshold value Nsl in the determination from the starting time to the steady time, the timer count is set as the starting point of the timer count, but in a high rotation region exceeding the threshold value Nsl. The timer may start counting when the actual rotational speed N converges to the target rotational speed Nt.

  In this embodiment, the deviation e = 0 is set as the convergence condition. However, the present invention is not limited to this.

  In the present embodiment, the timing of resetting the start flag Fst = 0 is performed with the elapse of the predetermined value Tsl of the timer T, but the start flag Tst is reset when the motor is stopped after the start. You may make it do.

DESCRIPTION OF SYMBOLS 1 Electric gear pump 2 Motor 3 Oil pump 31 Pump component 32 Motor component 34 Rotating shaft 1001 Controller 1002 Target rotation speed setting unit 1003 Feedback control amount calculation unit 1004 Inverter unit 1005 Voltage detection unit 1006 Rotation position estimation unit 1007 Rotation speed Estimator 1008 Feedback gain setting unit

Claims (5)

A brushless motor control device that performs feedback control by adjusting a motor control amount so as to converge a rotational speed of a rotationally driven motor to a target rotational speed,
A brushless motor control apparatus, wherein a coefficient of a feedback gain in a PID control value calculated by the feedback control is varied in accordance with an input voltage of the motor.   The control device for the brushless motor has a variable feedback gain coefficient lower than a normal control value until the actual rotational speed of the motor converges to a target rotational speed after the motor starts from a rotation stop state. 2. The feedback gain coefficient is varied according to the input voltage of the motor when the actual rotational speed of the motor converges to the target rotational speed at a predetermined rotational speed or higher. Brushless motor control device.   3. The brushless motor according to claim 2, wherein the brushless motor control device varies the coefficient of the feedback gain based on an actual rotation speed of the motor and an elapsed time converged to a target rotation speed of the motor. Control device.   The brushless motor control device fixes the variable feedback gain coefficient to a value lower than a normal control value when the target rotational speed of the motor shifts to feedback control in a direction in which the actual rotational speed decreases. The brushless motor control device according to claim 1, wherein:   5. The brushless motor control device according to claim 1, wherein the brushless motor control device is used for driving an electric liquid pump.

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