JP3962556B2 - Motor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a motor control device that switches a plurality of switching elements and outputs a driving current by controlling opening and closing of a current path to a winding of a permanent magnet type DC brushless motor.
[0002]
[Prior art]
  The direct current brushless motor is widely used as a control motor because it has a large torque generated at the time of start-up, little noise is generated, and rapid acceleration / deceleration is possible. In general, an inverter device is used for the drive, and the position of the rotor is detected by a hall sensor or the like to perform the switching control.
[0003]
  An example of such a motor control device is shown, for example, in Naoshi Mijo and Shigenobu Nagamori: New Brushless Motor, General Electronic Publishing Co., 2000, pp. 12-25. This motor control device drives a permanent magnet type DC brushless motor having three-phase windings with a three-phase inverter.
[0004]
  For this reason, this motor control device is provided with three position sensors using, for example, Hall elements, which detect the position of the rotor and generate a three-phase position signal. Then, each switching element constituting the inverter is turned on and off in a predetermined combination according to the combination of the position signals, whereby a drive current to the motor flows, torque is generated, and the rotor rotates. Furthermore, by sequentially changing the ON / OFF combination of the switching elements in accordance with the change in the combination of position signals accompanying the rotation of the rotor, a drive current flows through each winding continuously, Torque can be generated to continue the rotation.
[0005]
  In addition, the rotor can be rotated in either the forward or reverse direction by appropriately changing the on / off combination of the switching elements with respect to the current position signal combination.
[0006]
[Problems to be solved by the invention]
  In the above-described prior art, on / off of each switching element constituting the inverter is determined by the current combination of hall signals and the direction in which the rotor is to be rotated. However, when trying to rotate the motor in a certain direction, the direction in which the rotor tries to rotate in advance due to the inertia of the rotor and the motor load, the effect of external rotational force on the rotor, etc. May rotate in the opposite direction.
[0007]
  In such a case, when each switching element is turned on / off based only on the combination of the current Hall signal and the desired rotation direction, and each coil is energized by this on / off operation, it actually rotates. The direction in which the child rotates and the direction in which the voltage is applied to the winding are reversed, and the voltage applied to the winding and the counter electromotive force induced in the winding are in the same direction. . During this time, since the voltage applied to the winding and the back electromotive force induced in the winding are in the same direction, a voltage obtained by adding them is applied to the winding, and as a result, a large current is applied to the winding. Flows. And the strong magnetic flux which generate | occur | produced by this electric current penetrates the permanent magnet of a rotor against the magnetization direction, and there exists a problem that a permanent magnet demagnetizes and a motor performance falls.
[0008]
  The present invention has been made in view of the above problems, and prevents permanent magnets from demagnetizing even if the rotor of the DC brushless motor of the permanent magnet type rotates in the direction opposite to the direction of rotation. Reliable motor while preventing degradation of motor performanceAnd promptlyAn object of the present invention is to provide a motor control device that is reversed to rotate in the set rotation direction.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, the invention according to claim 1 detects a position of a rotor of a permanent magnet type DC brushless motor and outputs a multiphase position detection signal, and at least the rotor. A setting unit for setting the rotation direction ofThe time required for the rotor to naturally stop from the state where the rotor rotates in the direction opposite to the rotation direction set by the setting unit, and the time interval of the position detection signal determined by the rotation speed of the rotor. Based on the reference time interval of the position detection signal in the process of the natural deceleration of the rotor,The control unit determines the actual rotation direction of the rotor based on the position detection signal output from the position detection unit, and the determined actual rotation direction of the rotor and the setting set by the setting unit When it is determined that the rotation direction is opposite, the output of the drive current by the motor drive unit is prohibited, and after the prohibition control,The rotor is stopped when it is determined that the position detection signal does not change over the reference time interval.The motor driving unit is controlled so as to determine and rotate the rotor in the rotation direction set by the setting unit.
[0010]
  In the invention configured as described above, the control unit determines the rotation direction of the rotor of the DC brushless motor to be controlled based on the position detection signal, and the actual rotation direction determined by the setting unit is determined. If it is determined that the rotation direction is opposite, the output of the drive current by the motor drive unit is prohibited. For this reason, the permanent magnet demagnetization caused by an excessive current flowing in the winding is not applied to the winding in which the counter electromotive force is induced by the rotation of the rotor without applying a voltage in the same direction. Can be prevented.
[0011]
  Further, since the supply of drive current to the DC brushless motor to be controlled is stopped by the prohibition of output, the DC brushless motor to be controlled gradually decelerates and eventually stops. Since the controller starts driving the DC brushless motor to be controlled in the set rotation direction after determining the stop of the rotor, the controller prevents the permanent magnet from demagnetizing and prevents the motor performance from deteriorating. However, the rotation direction of the DC brushless motor to be controlled can be reliably reversed.
[0012]
  Moreover,As the rotor whose drive current is stopped decelerates, the time interval at which the position detection signal changes increases, but along with this, the time until the rotor stops stops. When this time interval reaches a certain value, the time until the rotor stops is zero. That is, when the position detection signal does not change over this time interval, it can be determined that the rotor has stopped.FromThe time interval is obtained in advance as a reference time interval, the time interval of the change of the position detection signal is measured, and when the value becomes this reference time interval, the stop is performed, so that the DC brushless motor to be controlled is The stop of the rotor can be determined reliably and in the shortest time.
[0013]
  Claims2The invention described in claim 11In the motor control device described in (1), the reference time interval is derived in advance for each DC brushless motor having different output characteristics and stored in a storage unit.
[0014]
  In the invention configured as described above, the reference time interval is derived for a plurality of DC brushless motors having different characteristics and stored in a storage unit inside the apparatus. Therefore, by selecting and using these reference time intervals according to the DC brushless motor to be controlled, it is possible to control a plurality of motors having different characteristics using the same control device. As a result, it is claimed without using a control device prepared for each DC brushless motor to be controlled.1 andThe same effect can be achievedAboveThe mass production efficiency of the apparatus can be increased and the cost can be reduced.
[0015]
  Claims3The invention described in claim 1Or 2When the actual rotation direction of the rotor determined by the control unit based on the position detection signal is the same as the rotation direction set by the setting unit, the rotor is set. The motor driving unit is controlled to rotate in the rotation direction.
[0016]
  In the invention configured as described above, if the actual rotation direction of the rotor of the DC brushless motor to be controlled is the same as the set rotation direction, there is no risk of demagnetization due to the drive current, so the control unit immediately sets. Drive control in the rotation direction. for that reason,In such a case,The motor operation control can be continuously performed without delay.There are also advantages.
[0017]
  Claims4The invention described in claim 1 to claim 13In the motor control device according to any one of the above, the setting unit sets the rotation direction of the rotor to be normal or reverse according to an external operation.
[0018]
  In the invention configured as described above, when the rotation direction is set in either the forward or reverse direction by the setting unit in accordance with an external operation, the control unit appropriately executes processing according to the rotation state of the rotor. Even if the external operation to set the rotation direction is performed in any rotation state of the DC brushless motor to be controlled, it does not cause problems such as demagnetization of permanent magnets or delays in starting, and it can be performed accurately. Can perform motor controlAlso has the effect.
[0019]
  Claims5The invention described in claim 1 to claim 14In the motor control device according to any one of the above, the DC brushless motor drives a hydraulic pump for power steering mounted on a vehicle to generate assist torque via a hydraulic cylinder, and the setting unit is controlled by a driver. The assist direction by the hydraulic cylinder is set according to a steering operation.
[0020]
  The invention thus configured is applied to drive control of a DC brushless motor as a power steering motor that is used by being connected to a hydraulic pump and an oil flow controlled by the hydraulic pump.The effects of the invention according to any one of claims 1 to 4 can be obtained.Prevents deterioration of motor performance due to demagnetization of permanent magnets during reversal,For power steeringThe motor durability of the DC brushless motor can be improved.
[0021]
  The present invention can also be applied to control of DC brushless motors for vehicles other than power steering motors, such as motors for power windows and door mirrors, and DC brushless motors other than those for vehicles. It is particularly suitable for controlling a direct current brushless motor connected to a load having a large inertia such as a power steering motor.
[0022]
  Furthermore, the present invention not only controls a permanent magnet type DC brushless motor that is rotationally driven in both forward and reverse directions, but also reverses from the outside with respect to the rotor and load even if the driven direction is constant. The present invention can also be applied to control of a permanent magnet type DC brushless motor used for applications in which the rotor may reversely rotate due to the action of the rotational force.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
  An embodiment in which the motor control device according to the present invention is applied to an electrohydraulic power steering device for an automobile will be described with reference to FIGS.
[0024]
  FIG. 1 is a connection diagram showing the configuration of the motor control device of this embodiment. As shown in FIG. 1, this motor control device is a permanent control target having three-phase windings as a power steering motor. In order to drive and control a magnet type DC brushless motor (hereinafter simply referred to as a motor) 40, an inverter 10 that is interposed between the motor 40 and the battery 30 and outputs a drive current to the windings of the motor 40; A control unit 50 is provided for controlling on / off of the switching elements constituting the inverter 10.
[0025]
  By the way, the motor 40 is integrated with a hydraulic pump (not shown), and the rotating shaft of the motor 40 drives the hydraulic pump to generate an oil flow. Then, by opening and closing a valve (not shown), an oil flow in a predetermined direction is introduced into a hydraulic cylinder provided in a steering gear box (not shown), thereby generating an assist thrust that reduces the steering operation.
[0026]
  Moreover, although the driving direction (rotating direction) of the motor 40 is one direction, depending on the state of the oil flow serving as the load, the motor 40 rotates by the action of the oil flow even when the motor 40 is not driven. The child may be spinning. The rotation direction may be opposite to the driving direction. In such a case, if a reverse drive current is unconditionally applied to the motor 40, demagnetization of the permanent magnet occurs as described above.
[0027]
  In addition, the stator of the motor 40 includes three Hall sensors 41, 42 and 43 that output a three-phase position detection signal as a position detection unit of the present invention. They are arranged radially at intervals. These three Hall sensors 41, 42 and 43 output H or L level position detection signals Hu, Hv and Hw according to the position of the magnetic poles of the rotor.
[0028]
  The inverter 10 corresponds to a motor drive unit according to the present invention, and is a switching element that controls opening and closing of a current path between the battery 30 and each winding of the motor 40 in accordance with switching control signals SG1 to SG6 from the control unit 50. And a flywheel diode that protects the transistors 11 to 16 from the back electromotive force generated in each winding, and returns the power generated in each winding to the battery 30 when the motor 40 operates as a generator. 21 to 26.
[0029]
  Further, a steering sensor 51 provided on a rotating shaft of a steering handle (not shown) operated by the driver is connected to the control unit 50. When the driver operates the steering handle, the steering sensor 51 is A steering operation signal corresponding to the rotation angle is output. Based on the steering operation signal output from the steering sensor 51, the control unit 50 determines opening / closing of the valve and driving / stopping of the motor 40 for generating assist thrust, and from the hall sensors 41, 42 and 43. Based on the output position detection signals Hu, Hv and Hw, switching control signals SG1 to SG6 for turning on and off the transistors 11 to 16 are output at a predetermined timing.
[0030]
  Further, the control unit 50 is a switching control signal for turning off all the transistors 11 to 16 when the actual rotation direction of the rotor detected based on the position detection signals Hu, Hv, and Hw is different from the driving direction. SG1 to SG6 are output. Further, when the control unit 50 determines that the motor 40 has been stopped by turning off all the transistors 11 to 16, the control unit 50 immediately outputs an on control signal to a predetermined transistor to start driving the motor 40. Thus, in this embodiment, the control unit 50 functions as the setting unit and the control unit of the present invention.
[0031]
  Next, the operation of the motor control device of this embodiment will be described with reference to FIGS. FIG. 2 is a truth table showing the correspondence between the combination of the position detection signals Hu, Hv, and Hw and the combination of the switching control signals SG1 to SG6 for turning on / off each transistor, and FIG. 3 shows the position detection signals Hu, Hv. , Hw, switching control signals SG1 to SG6, and a timing chart showing changes in drive current. FIG. 4 is a flowchart showing the operation of the control unit in this embodiment, and FIG. 5 is a flowchart showing the operation during motor drive processing.
[0032]
  Here, as shown in FIG. 3, the rotation direction in which the combination of the position detection signals from the hall sensors 41 to 43 changes in the order of Hu, Hv, and Hw is the forward direction, and the opposite direction is the reverse direction. It is defined as At this time, in the combination of the position detection signals Hu, Hv, and Hw shown in the truth table of FIG. 2, the direction of transition from the upper row to the lower row corresponds to the forward direction, and the direction of transition from the lower row to the upper row corresponds to the reverse direction. The driving direction of the motor 40 set by the control unit 50 is assumed to be the positive direction.
[0033]
  In this embodiment, the control unit 50 performs the processing steps S1 to S11 shown in the flowchart of FIG. 4 for each processing cycle, and outputs the position detection signals Hu, Hv, Hw is detected to determine the rotation direction of the rotor.
[0034]
  First, the control unit 50 detects the current position detection signals Hu, Hv, Hw output from the hall sensors 41, 42, and 43, and stores the combination (hereinafter referred to as the current pattern) in the internal memory (step). S1). A combination of position detection signals Hu, Hv, and Hw one cycle before that is detected in the immediately preceding processing cycle and stored in the internal memory (hereinafter referred to as the previous pattern), and the current pattern detected in step S1 Are compared (step S2). As a result of comparing the previous pattern and the current pattern (step S3), if there is a change in the pattern of the position detection signals Hu, Hv, Hw, the rotational direction of the rotor is determined as follows based on the change. (Step S4).
[0035]
  For example, it is assumed that the current pattern of the position detection signals Hu, Hv, and Hw is a combination of (H, L, H) at time t1, as shown in FIG. At this time, the control unit 50 compares this pattern with the previous pattern stored in the internal memory to determine the rotation direction of the rotor. That is, if the previous pattern is (L, L, H) shown in the first column of FIG. 2 with respect to the current pattern (H, L, H) located in the second column of the truth table of FIG. Since the patterns of the position detection signals Hu, Hv, and Hw shift from the upper row to the lower row in FIG. 2 as the rotor rotates, it is determined that the rotor is rotating in the positive direction at this time. . If the previous pattern is (H, L, L) shown in the third column of FIG. 2, the patterns of the position detection signals Hu, Hv, Hw are shifted from the lower column to the upper column of FIG. From this, it is determined that the rotor is rotating in the opposite direction at this time. Similarly, when the current pattern is in another combination, the rotation direction of the rotor is determined by comparing the current pattern with the previous pattern. Subsequently, the control unit 50 resets an internal timer (not shown) described later (step S5).
[0036]
  On the other hand, when there is no change in the pattern of the position detection signals Hu, Hv, and Hw in step S3 described above, that is, when the current pattern and the previous pattern are the same pattern, the control unit 50 performs the following process. Determine if the rotor is stopped.
[0037]
  First, it is confirmed whether or not it has been determined in the previous processing cycle that the rotor is in a stopped state (step S8). As a result, if the rotor is already stopped, the processing step proceeds to step S6. On the other hand, if the determination that the vehicle is in the stopped state has not been made yet, the control unit 50 increments the internal timer (step S9).
[0038]
  By the way, this internal timer is configured to continue counting if there is no change in the combination of the position detection signals Hu, Hv, Hw (step S9), and is reset when there is a change (step S5). In other words, this internal timer measures the time during which the position detection signals Hu, Hv, Hw are not changed and hold a certain combination. And if this combination does not change over the predetermined time mentioned later, the control unit 50 will determine with the rotor having stopped.
[0039]
  Thus, the control unit 50 checks whether or not the time during which the combination of the position detection signals Hu, Hv, and Hw measured by the internal timer does not change has reached the time required for the preset stop determination (step S10). ). If the predetermined time has elapsed, it is determined that the rotor is in a stopped state (step S11), and the processing step proceeds to step S6. On the other hand, if it is determined in step S10 that the predetermined time has not elapsed, it cannot be determined that the rotor is stopped at this time, and the process directly proceeds to step S6.
[0040]
  As described above, the control unit 50 executes the above-described steps S1 to S11 based on the position detection signals Hu, Hv, and Hw output from the hall sensors 41, 42, and 43, thereby rotating the rotor. (Either forward rotation, reverse rotation, or stop) is determined.
[0041]
  Thereafter, based on the output signal from the steering sensor 51, it is determined whether or not the motor 40 needs to be driven in accordance with the steering operation by the driver (step S6). If it is not necessary to drive the motor 40, the processing step returns to step S1, and the above series of operations are repeated. If it is necessary to drive the motor 40, a motor drive process (step S7), which will be described in detail later, is executed, and the process returns to step S1.
[0042]
  Here, the “predetermined time” for performing the stop determination can be obtained as follows. That is, since the time intervals of changes in the position detection signals Hu, Hv, and Hw are inversely proportional to the rotational speed of the rotor, this time interval increases as the rotor decelerates, but eventually the rotor stops and the position is detected. The signals Hu, Hv, Hw do not change. That is, this time interval is maximized immediately before the rotor stops. On the other hand, as the rotor decelerates, the time until the rotor stops is shortened, and this time is minimized immediately before the rotor stops. Therefore, in a rotor that is rotating in reverse at a certain rotational speed, if the total time of the time interval of the change of the position detection signals Hu, Hv, Hw at that rotational speed and the time until the rotor stops is elapsed, It can be determined that the motor is stopped. Since it can be determined that the rotor has stopped unless a change in the position detection signals Hu, Hv, Hw is detected during the minimum value of the total time, this minimum value is obtained in advance as a reference time interval in the present invention, This reference time interval is set as the “predetermined time” necessary for stop determination.
[0043]
  Specifically, a position detection signal determined by the rotor deceleration characteristics obtained from the output and load characteristics of the motor 40, the structure of the motor 40 (the arrangement of the magnetic pole structure of the rotor and the Hall sensor), and the rotational speed of the rotor. The reference time interval can be obtained from the period of change of.
[0044]
  Since the reference time interval is determined by the characteristics of the motor 40 as described above, the reference time interval is different for each motor 40 having different characteristics. Therefore, for each motor 40 having a plurality of characteristics, a reference time interval for each motor 40 having each characteristic is derived in advance and stored in the internal memory of the control unit 50, and a reference time interval corresponding to the motor 40 to be used is determined. It can be read and used for control. By doing so, it becomes possible to control the motor 40 having different characteristics using the same control unit. At this time, the internal memory storing these reference time intervals corresponds to the storage unit referred to in the present invention.
[0045]
  Next, the operation of the motor drive process (step S7 in FIG. 4) will be described with reference to FIG.
[0046]
  When it is necessary to drive the motor 40 by the driver's steering operation (step S6), first, it is confirmed whether or not the rotor is already stopped (step S71). If the rotor is in a stopped state, the process proceeds to step S73, and the drive of the motor 40 is permitted. If the rotor is not stopped, that is, if the rotor is rotating in any direction, the direction of rotation is checked (step S72). If the rotation direction is the reverse direction, the control unit 50 prohibits driving of the motor 40 (step S74). If the rotational direction is the positive direction, the drive of the motor 40 is permitted (step S73).
[0047]
  Thus, when the drive of the motor 40 is permitted, the control unit 50 turns on a predetermined transistor based on the truth table of FIG. That is, as shown in FIG. 3, the transistors 11 and 16 are turned on as shown in FIGS. 2 and 3 with respect to the combination (H, L, H) of the position detection signals Hu, Hv, and Hw at time t1. An ON control signal (that is, SG1 and SG6) is output. At this time, when the transistor 11 and the transistor 16 are turned on, the positive side terminal of the battery 30 passes through the transistor 11, the U-phase motor winding, the W-phase motor winding, and the transistor 16 to the negative side terminal of the battery 30. A returning conductive path is formed, and a current flowing along the conductive path generates a torque in the positive direction, and the rotor rotates in the positive direction.
[0048]
  Then, as the pattern of the position detection signals Hu, Hv, and Hw sequentially changes with the rotation of the rotor, the ON control signal pattern is sequentially changed in accordance with the truth table of FIG. 2, as shown in FIG. The three-phase driving currents Iu, Iv, and Iw flowing through the three-phase windings by 120 ° flow to each other, and torque is continuously generated, so that the rotor continues to rotate in the positive direction.
[0049]
  On the other hand, if the rotation direction of the rotor is the reverse direction in step S72, the control unit 50 prohibits driving of the motor 40 and outputs an off control signal for turning off all the transistors 11-16. As a result, all transistors are cut off, and at this time, the motor 40 enters a regenerative braking state. That is, the motor 40 operates as a generator, converts its kinetic energy into electrical energy, and returns the energy to the battery 30 via the flywheel diodes 21 to 26, so that the rotational speed is rapidly reduced. I will stop.
[0050]
  Thus, even when the motor 40 should be driven according to the driver's steering operation, if the rotation of the rotor at that time is in the reverse direction, the control unit 50 prohibits drive current output by the inverter 10. is doing. For this reason, the drive current in the rotation direction opposite to the rotation of the rotor is not passed, and the demagnetization of the permanent magnet that has occurred in the prior art can be suppressed.
[0051]
  For example, in order to verify the demagnetization effect at this time, as a result of calculating the demagnetization factor by measuring the effective value of the induced voltage of the motor winding, the demagnetization when the transistors 11 to 16 are not forcibly turned off as in the prior art. While the magnetic susceptibility was 3.4%, the demagnetization factor when the transistors 11 to 16 were forcibly turned off as in this embodiment was reduced to about 1%, which was within the measurement error range.
[0052]
  Further, when the magnetic flux density distribution of the permanent magnet of the rotor is measured, the magnetic flux density when the transistors 11 to 16 are not forcibly turned off as in the prior art is as shown in FIG. Disturbance of the distribution representing the influence of demagnetization occurs near the boundary, whereas the magnetic flux density when the transistors 11 to 16 are forcibly turned off as in this embodiment is as shown in FIG. It was found that there was no disturbance and no demagnetization occurred.
[0053]
  In this embodiment, the rotor stop determination is performed in the minimum necessary time based on changes in the position detection signals Hu, Hv, and Hw, so that the rotor rotating in the reverse direction is in the forward direction. Time delay until inversion can be reduced.
[0054]
  Further, since the inverter 10 immediately outputs a drive current when the rotor is stopped or rotating in the positive direction, an assist thrust can be generated immediately following the driver's steering operation.
[0055]
  In the above, one combination of the three-phase position detection signals Hu, Hv, and Hw has been described. Even when the combination of the position detection signals Hu, Hv, and Hw is another pattern, the current pattern and the previous pattern , The rotation direction is determined, and the transistors 11 to 16 are turned on and off based on the result, whereby the motor 40 can be appropriately controlled.
[0056]
  By the way, in the above example, the rotation direction set by the control unit 50 is only the forward direction. However, even when the set rotation direction is the reverse direction, the truth table of FIG. It is possible to control the rotation of the motor 40 in the same way only by changing the signal waveform change order.
[0057]
  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.
[0058]
  For example, in the present embodiment, each of the transistors 11 to 16 constituting the inverter 10 is switched by a simple on / off signal determined by a combination of the position detection signals Hu, Hv, and Hw, and as a result, flows in each winding. The waveform of the current is a rectangular wave as shown in FIG. 3, but as a method for driving the inverter 10, for example, PWM driving for switching a transistor at a high frequency may be used. At this time, torque pulsation is reduced, and smoother rotation can be obtained.
[0059]
  In the present embodiment, the three hall sensors 41, 42 and 43 as the position detection unit are arranged at an angular interval of 40 °, but this interval is not limited to this, and another angle is provided. It may be an interval. Further, the position detection unit of the present invention may be optical means using a photo interrupter, for example, besides the above-described Hall sensor.
[0060]
  In this embodiment, the motor 40 has a three-phase stator winding, and the rotor is a six-pole permanent magnet type rotor in which six permanent magnets are provided on the periphery thereof. The present invention can also be applied to motors having different numbers of winding phases and rotor poles.
[0061]
  Further, in this embodiment, the control unit 50 is configured by a microprocessor having an internal memory, for example, and the determination of the rotation direction of the rotor and the output / stop of the switching control signal are all performed by software. In addition, the present invention can be realized by hardware. For example, an output limiting circuit may be provided at the gate terminal of each transistor, and the output limiting circuit may forcibly turn off the output of each transistor when the actual rotation direction of the rotor is the reverse direction.
[0062]
  Although the case where the motor control device of the present invention is applied to control of a permanent magnet type DC brushless motor as a power steering motor of an automobile has been described here, the object to which the present invention can be applied is limited to this. The present invention can be similarly applied to control of various types of motors other than the on-vehicle and non-on-vehicle motors, in which the motor to be controlled is a permanent magnet type DC brushless motor. .
[0063]
【The invention's effect】
  As described above, according to the first aspect of the present invention, the control unit determines the rotation direction of the rotor of the permanent magnet type DC brushless motor to be controlled based on the position detection signal, and is set by the setting unit. If it is determined that the determined rotation direction is opposite to the determined actual rotation direction, output of the drive current by the motor drive unit is prohibited. For this reason, the permanent magnet demagnetization caused by an excessive current flowing in the winding is not applied to the winding in which the counter electromotive force is induced by the rotation of the rotor without applying a voltage in the same direction. Can be prevented.
[0064]
  Further, since the supply of driving current to the permanent magnet type DC brushless motor to be controlled is stopped by prohibiting the output, the DC brushless motor to be controlled gradually decelerates and eventually stops. Then, after the control unit determines and confirms that the rotor of the DC brushless motor to be controlled is stopped, the controller starts driving the DC brushless motor to be controlled in the set rotation direction, thereby preventing demagnetization of the permanent magnet. Thus, it is possible to reliably reverse the rotation direction of the DC brushless motor to be controlled while preventing the motor performance from deteriorating.
[0065]
  Moreover,The maximum value of the time interval of the change of the position detection signal is obtained in advance as a reference time interval, the time interval of the change of the position detection signal is measured, and when the value reaches the maximum value, it is determined that the rotor is stopped.To doThe stop of the rotor of the DC brushless motor to be controlled can be determined reliably and in a short time. Based on this determination, the DC brushless motor to be controlled can be reliably and promptly prevented while preventing demagnetization of the permanent magnet. It is possible to shift to reverse operationwear.
[0066]
  Therefore, even if the rotor of the permanent magnet type DC brushless motor rotates in the direction opposite to the direction in which it is intended to rotate, the permanent magnet is prevented from demagnetizing and the motor performance is not deteriorated. Reverses reliably and quickly and rotates in the set rotation directionThere is a unique effect.
[0067]
  Claims2According to the invention described in claim1The maximum time interval as the reference time interval is derived for a plurality of DC brushless motors having different characteristics, and these values are stored in a storage unit inside the device. Therefore, since a plurality of motors having different characteristics can be controlled using the same control device, the DC brushless motors having different properties can be claimed without using a control device prepared for each motor.Invention of 1Can have the same effect asMoreover,Increases mass production efficiency of equipment and reduces costsThere are also advantages.
[0068]
  Claims3According to the invention described in claim 1,Or 2In the motor control described above, if the rotation direction of the rotor is the same as the set rotation direction, there is no risk of demagnetization due to the drive current, so the control unit immediately performs drive control in the set rotation direction. Therefore, claim 1Or invention of 2In addition to the above effect, when the actual rotation direction of the rotor is the same as the set rotation direction, the operation control of the DC brushless motor to be controlled can be continuously performed without delay.
[0069]
  Claims4According to the invention described in claim 1, the claims 1 to3In the motor control described in any one of the above, when the rotation direction is set in either the forward or reverse direction by the setting unit according to an external operation, the control unit appropriately executes a process according to the rotation state of the rotor Therefore, regardless of the rotation state of the DC brushless motor to be controlled, the external operation for setting the rotation direction can be performed accurately without causing problems such as demagnetization of the permanent magnet or delay in startup. Motor control can be performedAlso has the effect.
[0070]
  Claims5According to the invention described in claim 1, the claims 1 to4In the motor control device according to any one of the above, the present invention is applied to drive control of a DC brushless motor for power steering which has a large inertia load of a hydraulic pump and an oil flow controlled by the hydraulic pump and which requires high durability.The effect of any one of claims 1 to 4 can be achieved.Prevents deterioration of motor performance due to demagnetization of permanent magnets during reversal,For power steeringThe motor durability of the DC brushless motor can be improved.
[Brief description of the drawings]
FIG. 1 is a connection diagram illustrating a configuration of a motor control device according to an embodiment of the present invention.
FIG. 2 is a truth table showing correspondence between position detection signals and switching control signals.
FIG. 3 is a timing chart showing the relationship between a position detection signal, a switching control signal, and a drive current.
FIG. 4 is a flowchart showing the operation of the motor control device of this embodiment.
FIG. 5 is a flowchart showing an operation of motor drive processing.
FIG. 6 is a distribution diagram of magnetic flux density measured at an outer peripheral portion of a permanent magnet type rotor in a comparative example.
FIG. 7 is a distribution diagram of magnetic flux density measured at the outer peripheral portion of the permanent magnet type rotor according to the embodiment of the present invention.
[Explanation of symbols]
  10 Inverter (motor drive unit)
  11-16 Transistor (switching element)
  21-26 Flywheel diode
  30 battery
  40 DC brushless motor
  41, 42, 43 Hall sensor (position detector)
  50 Control unit (control unit, setting unit)
  51 Steering sensor
  Hu, Hv, Hw Position detection signal
  SG1 to SG6 switching control signal

Claims (5)

A plurality of switching elements constituting the motor drive unit are switched by a control signal of the control unit, and the energization path to the winding of the permanent magnet type DC brushless motor is controlled to open and output a drive current to the DC brushless motor. In the motor control device,
A position detector that detects the position of the rotor of the DC brushless motor and outputs a multi-phase position detection signal; and
A setting unit for setting at least the rotation direction of the rotor,
The time required for the rotor to naturally stop from the state where the rotor rotates in the direction opposite to the rotation direction set by the setting unit, and the time interval of the position detection signal determined by the rotation speed of the rotor. Based on the reference time interval of the position detection signal in the process of the natural deceleration of the rotor,
The control unit is
Determine the actual rotation direction of the rotor based on the position detection signal output from the position detection unit,
When it is determined that the determined actual rotation direction of the rotor and the set rotation direction set by the setting unit are opposite, the output of the drive current by the motor drive unit is prohibited and controlled,
After the prohibition control, when it is determined that the position detection signal does not change over the reference time interval, it is determined that the rotor has stopped, and the rotor is rotated in the rotation direction set by the setting unit. A motor control device for controlling a motor drive unit. The motor control device according to claim 1, wherein the reference time interval is derived in advance for each DC brushless motor having different output characteristics and stored in a storage unit. The control unit is
When the actual rotation direction of the rotor determined based on the position detection signal is the same as the rotation direction set by the setting unit, the rotor is rotated in the set rotation direction without determining stoppage. The motor control device according to claim 1 or 2 , wherein the motor driving unit is controlled to perform the control. 4. The motor control device according to claim 1 , wherein the setting unit sets the rotation direction of the rotor to be normal or reverse according to an external operation . 5. The DC brushless motor drives a hydraulic pump for power steering mounted on a vehicle and generates assist torque via a hydraulic cylinder.
The motor control device according to any one of claims 1 to 4, wherein the setting unit sets an assist direction by the hydraulic cylinder in accordance with a steering operation by a driver .

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