JP2012223065A - Motor position detector and motor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the rotation position of a rotor even when a hall device detection signal changes due to a temperature change or a variation in device quality.SOLUTION: A motor position detector comprises hall devices which, upon detecting a magnetic field from magnets for magnetic fields disposed on a rotor, output a hall signal U in sinusoidal waveform; and a zero-cross detection circuit, having a first threshold (0(V)), a second threshold Th2 smaller than the first threshold and a third threshold Th3 larger than the first threshold, which compares the hall signal U with the thresholds and then outputs a position detection signal Spu indicating the rotation position of the rotor. The zero-cross detection circuit, while the first threshold having been set, switches its threshold to the second threshold synchronously when the hall signal U has increased to cross the first threshold and then restores it to the first threshold with prescribed timing, or switches its threshold to the third threshold synchronously when the hall signal U has decreased to cross the first threshold and then restores it to the first threshold with prescribed timing.

Description

  The present invention relates to a motor position detection device that detects the position of a mover of a motor and a motor using the same.

  The brushless motor includes a cylindrical stator and a cylindrical rotor that is provided to face the inner periphery or outer periphery of the stator and is rotatably provided with respect to the stator around a rotation axis. A field magnet is disposed along the circumferential direction of the rotor. A winding is wound around the stator core of the stator, and the rotor is rotated by the action of an electromagnetic field generated by passing a driving current through the winding and a magnetic field of the field magnet. In addition, the brushless motor includes a position detection sensor that detects the rotational position of the rotor in order to accurately control the rotation of the rotor.

  By the way, in a brushless motor, when a position detection error occurs in the position detection sensor, accurate rotation control of the brushless motor cannot be performed and efficiency is lowered. This position detection sensor generally uses a Hall element, and detects the rotational position of the rotor by detecting the zero cross of the detection signal (hereinafter referred to as “Hall signal”) output from this Hall element. ing. In this case, in order to prevent chattering of the zero cross detection circuit, the zero cross detection circuit has a hysteresis characteristic. However, due to the influence of this hysteresis, there arises a problem that the zero-cross detection position of the Hall signal deviates from the original zero-cross position.

  In order to cope with this problem, conventionally, a sensor magnet is provided for the Hall element to detect a magnetic pole change, separately from the field magnet. Then, the sensor magnet is shifted from the field magnet by a mechanical angle corresponding to the shift of the zero-cross detection position caused by hysteresis, thereby preventing the shift of the zero-cross detection position (for example, Patent Document 1). See).

JP 2004-23800 A

  By the way, the conventional method as described above can cope with the case where the amplitude of the Hall signal changes due to temperature, element variation, voltage supplied to the Hall element, current variation, etc., and the deviation of the zero cross position changes. It becomes difficult.

  9 and 10 are diagrams for explaining the operation of a conventional motor position detection apparatus. FIG. 9 shows a case where the amplitude of the Hall signal U is large, and FIG. 10 shows a case where the amplitude of the Hall signal U is small. As shown in FIG. 9, the threshold value Th1 and the threshold value Th2 are set on the positive side and the negative side of the center voltage 0 (V), respectively, so that the zero-cross detection circuit has hysteresis characteristics. In the conventional zero cross detection circuit, the polarity of the position detection signal Sp is changed at the timing when the Hall signal U crosses the threshold Th1 and the threshold Th2. Therefore, the zero-cross detection position is a time T01 that is delayed by a position detection error Te from the original time T0 of the zero-cross position. If the position detection error Te is always constant, the position detection error Te can be corrected by subtracting the position detection error Te from the zero-cross detection position to obtain a correct zero-cross position.

  However, when the amplitude of the Hall signal U changes due to a temperature change around the Hall element, the position detection error Te changes. For example, as shown in FIG. 10, when the amplitude of the Hall signal U becomes small, the slope of the sine wave signal at the zero cross point of the Hall signal U becomes small, so the position detection error Te is compared with the case of FIG. Become bigger. As described above, when the value of the position detection error Te changes due to a temperature change or the like, it is difficult to correct the error, and there is a problem that normal rotation control of the brushless motor cannot be performed.

  The present invention has been made to solve such problems, and can accurately detect the position of the motor mover even if the detection signal of the Hall element changes due to temperature change, element variation, or the like. An object of the present invention is to provide a motor position detection device capable of performing the above and a motor using the same.

  In order to achieve the above object, a motor position detection device according to the present invention includes a stator and a stator arranged opposite to the stator, and at least one pair of N-pole and S-pole permanent magnets along the moving direction. A motor position detection device including a plurality of movable elements arranged alternately, a magnetic sensor that detects a magnetic field from a permanent magnet and outputs a sine wave-shaped magnetic detection signal, and a first threshold value A zero cross that includes a second threshold value smaller than the first threshold value and a third threshold value greater than the first threshold value, and outputs a position detection signal indicating the position of the mover by comparing the magnetic detection signal with the threshold value. A zero-cross detection circuit, wherein the first threshold value is set, the magnetic detection signal increases, and the threshold value is switched to the second threshold value at the timing when the first threshold value is crossed. To return to the first threshold at the timing of The threshold at the timing when the output signal crosses the first threshold value decreases after switching to the third threshold value, characterized in that to return to the first threshold value at a predetermined timing.

  Accordingly, the position of the mover can be detected at the zero cross timing of the magnetic detection signal, and the threshold value of the zero cross detection circuit can be provided with a hysteresis characteristic to prevent chattering. Thereby, the exact position of the mover can be detected, the position control accuracy of the mover can be increased, and the high efficiency of the motor can be maintained.

  In the motor position detection apparatus of the present invention, the motor is a rotary three-phase motor, and the predetermined timing for returning the threshold value to the first threshold value is that the other-phase magnetic detection signal crosses the first threshold value. It is good also as a timing to do.

  As a result, since the return to the first threshold is performed at the zero cross timing of the magnetic detection signal of the other phase, the threshold can be reliably returned to the first threshold even if the rotation speed or the rotation direction of the rotor changes. Thus, the rotational position of the rotor can be reliably detected. In addition, since it is not necessary to create a special timing signal for returning the threshold value to the first threshold value, the circuit configuration can be simplified.

  In the motor position detection apparatus of the present invention, the predetermined timing for returning the threshold value to the first threshold is a timing that is delayed by a predetermined time from the timing at which the magnetic detection signal crosses the first threshold. Also good.

  As a result, the threshold value is returned to the first threshold value after a predetermined time set in advance from the time of zero cross detection, so that even in the case of a rotary three-phase motor, the magnetic detection signal of the other phase is unnecessary, and the magnetic sensor The present invention can also be applied to a single case. Even when the rotation direction of the rotor changes, no special control is required.

  In the motor position detection apparatus according to the present invention, the predetermined timing for returning the threshold value to the first threshold value is a timing that crosses the third threshold value when the magnetic detection signal is increased. When the detection signal is decreasing, it may be the timing when it crosses the second threshold.

  Thus, the return of the threshold value to the first threshold value is performed at the timing when the magnetic detection signal crosses the second threshold value or the third threshold value, so that the magnetic detection signal of the other phase can be obtained even in the case of a rotary three-phase motor. Is unnecessary, and can be applied to the case where there is one magnetic sensor. Even when the rotation direction of the rotor changes, no special control is required. Further, no special circuit for returning the threshold value to the first threshold value is required, and the circuit can be simplified and the cost can be reduced.

  A motor according to the present invention includes any one of the above-described motor position detection devices.

  According to the present invention, a motor position detecting device capable of accurately detecting the position of a motor mover even if a detection signal of a Hall element changes due to temperature change, element variation, or the like, and a motor using the same Can be provided.

The figure which shows the cross section of the brushless motor in Embodiment 1 of this invention. The figure which shows the inside of the motor case of the brushless motor from the top, and shows the arrangement relation between the stator iron core and the permanent magnet The figure which shows the inside of the motor case of the brushless motor from the top, and shows the arrangement relation between the stator iron core and the circuit board Block diagram showing the configuration of the drive control circuit of the brushless motor The figure which shows the structure of the motor rotor position detection apparatus in Embodiment 1 of this invention. The figure explaining position detection operation of the motor rotor position detection device The figure explaining the position detection operation | movement of the motor rotor position detection apparatus in Embodiment 2 of this invention. The figure explaining the position detection operation | movement of the motor rotor position detection apparatus in Embodiment 3 of this invention. The figure explaining the position detection operation | movement of the conventional motor rotor position detection apparatus. The figure explaining the position detection operation | movement of the conventional motor rotor position detection apparatus.

  A motor position detection apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a cross section of a brushless motor 10 according to Embodiment 1 of the present invention. In this embodiment, an example of an inner rotor type brushless motor in which a rotor as a mover is rotatably disposed on an inner peripheral side of a stator as a stator will be described as a motor. As shown in FIG. 1, the brushless motor 10 includes a stator 11, a rotor 12, a circuit board 13, and a motor case 14. The motor case 14 is formed of a sealed cylindrical metal, and the brushless motor 10 has a configuration in which the stator 11, the rotor 12, and the circuit board 13 are accommodated in the motor case 14.

  In FIG. 1, the stator 11 is configured by winding a winding 16 for each phase around a stator core 15. In the present embodiment, an example will be described in which a winding 16 divided into three phases of a U phase, a V phase, and a W phase that are 120 degrees out of phase with each other is wound around the stator core 15. The stator iron core 15 has a plurality of salient poles protruding toward the inner peripheral side. Further, the outer peripheral side of the stator iron core 15 has a substantially cylindrical shape.

  A rotor 12 is inserted inside the stator 11 via a gap. The rotor 12 holds a cylindrical permanent magnet 18 on the outer periphery of the rotor frame 17, and is disposed so as to be rotatable around a rotating shaft 20 supported by a bearing 19. That is, the front end surface of the salient pole of the stator core 15 and the outer peripheral surface of the permanent magnet 18 are arranged to face each other.

  Further, in the brushless motor 10, a circuit board 13 on which various circuit components 31 are mounted is built in a motor case 14. These circuit components 31 constitute a drive control circuit for controlling and driving the motor. In addition, in order to detect the rotational position of the rotor 12, a Hall element 38 as a magnetic sensor is also mounted on the circuit board 13. A support member 21 is attached to the stator core 15, and the circuit board 13 is fixed in the motor case 14 via the support member 21. Ends of the U-phase, V-phase, and W-phase windings 16 are led out from the stator 11 as lead wires 16 a, and the lead wires 16 a are connected to the circuit board 13.

  2 and 3 are views showing the inside of the motor case 14 of the brushless motor 10 according to the present embodiment from above. 2 and 3 show the stator core 15 in a state where the winding 16 is not wound. 2 shows the positional relationship between the stator core 15 and the permanent magnet 18, and FIG. 3 shows the positional relationship between the stator core 15 and the hall element 38. As shown in FIG.

  First, as shown in FIG. 2, the stator iron core 15 includes an annular yoke 15a and teeth 15b as salient poles. In the present embodiment, an example having twelve teeth 15b with 12 salient poles is given. The outer periphery of the stator core 15 is fixed to the inner surface of the motor case 14. Each of the teeth 15b extends and protrudes toward the inner peripheral side, and is disposed at equal intervals in the circumferential direction while forming slots that are spaces between the teeth 15b. The teeth 15b are sequentially associated with any one of the U phase, the V phase, and the W phase. A U-phase winding 16 is wound around the U-phase teeth 15b, a V-phase winding 16 is wound around the V-phase teeth 15b, and a W-phase winding is wound around the W-phase teeth 15b. 16 is wound.

  Further, the rotor 12 is disposed on the inner peripheral side facing the tip portions of the twelve teeth 15b. The permanent magnet 18 held by the rotor 12 is magnetized at equal intervals in the circumferential direction which is the moving direction (rotation direction) of the mover so that at least a pair of S poles and N poles are alternately arranged. . As shown in FIG. 2, the permanent magnet 18 of the present embodiment is magnetized so that there are four pairs of S poles and N poles, that is, eight poles in the circumferential direction. As described above, the brushless motor 10 has an 8-pole 12-slot configuration.

  Next, as shown in FIG. 3, three Hall elements 38, which are Hall elements 38 U, 38 V, and 38 W, are mounted on the circuit board 13 together with various circuit components 31. The Hall elements 38U, 38V, 38W are arranged on the circuit board 13 so as to face one end face of the cylindrical permanent magnet 18. On the circuit board 13, the Hall elements 38U, 38V, and 38W are disposed on the extending direction side of the teeth 15b corresponding to the U phase, the V phase, and the W phase, respectively. Thereby, Hall element 38U, 38V, 38W detects the magnetic pole of permanent magnet 18 corresponding to U phase, V phase, and W phase, respectively.

  In addition, when it is set as the structure of 8 poles 12 slots like this Embodiment, detailed description is abbreviate | omitted, However, by arrange | positioning Hall elements 38U, 38V, and 38W at 120 degree intervals in a mechanical angle, respectively, From the hall elements 38U, 38V, and 38W, U-phase, V-phase, and W-phase position detection signals having different electrical angles of 120 degrees can be obtained. That is, as shown in FIG. 3, the Hall element 38U is opposed to the U-phase tooth 15b along the u-axis, and the Hall element 38V is opposed to the V-phase tooth 15b along the v-axis. The Hall element 38W is disposed along the W-phase tooth 15b. Accordingly, as can be seen with reference to FIG. 2, the Hall elements 38U, 38V, 38W are arranged so as to deviate from the magnetic poles of the permanent magnet 18 every 120 degrees in electrical angle. The rotational positions of the U phase, V phase, and W phase can be detected from 38V and 38W.

  By supplying a power supply voltage and a control signal from the outside to the brushless motor 10 configured as described above, a drive current flows through the winding 16 by the control circuit and the drive circuit of the circuit board 13, and the stator core 15 Magnetic field is generated. The magnetic field from the stator iron core 15 and the magnetic field from the permanent magnet 18 generate an attractive force and a repulsive force according to the polarities of the magnetic fields, and the rotor 12 rotates around the rotating shaft 20 by these forces.

  Next, a drive control circuit constituted by the Hall element 38 and the circuit component 31 mounted on the circuit board 13 will be described.

  FIG. 4 is a block diagram showing the configuration of the drive control circuit 40 of the brushless motor 10 in the present embodiment.

  The drive control circuit 40 includes a rotation control unit 41, a drive waveform generation unit 42, a PWM circuit 43, an inverter 44, a position data generation unit 45, a phase control unit 46, and a zero cross detection circuit 50 along with the three Hall elements 38. Here, the three rotor elements 38 and the zero cross detection circuit 50 constitute a motor rotor position detection device 60 as a motor position detection device. The drive control circuit 40 is notified of rotation command data Dr for instructing a rotation speed, a rotation position, and the like from, for example, an external host device.

  The rotation command data Dr is notified to the rotation control unit 41. The rotation control unit 41 is notified of the detected position data Dp generated by the position data generation unit 45. The detected position data Dp is basically data obtained by detecting the rotational position of the rotor 12.

  The Hall element 38 detects a change in the magnetic pole of the rotating permanent magnet 18, and the detection signal is input to the zero cross detection circuit 50, and the rotation position detection signals Spu, Spv, Spw generated by the zero cross detection circuit 50 are the position data generation unit 45. And supplied to the phase controller 46. The position data generator 45 generates rotational position data Dp from the rotational position detection signal Sp. Detailed operation of the zero cross detection circuit 50 will be described later.

  The rotation control unit 41 generates rotation control data Dd indicating the drive amount to the winding 16 based on the rotation command data Dr and the detected position data Dp.

  Specifically, when speed control of the brushless motor 10 is performed, the rotation control unit 41 obtains a speed deviation between the rotation command data Dr indicating the speed command and the detected speed data calculated from the detected position data Dp by differentiation or the like. . And the rotation control part 41 produces | generates the rotation control data Dd which shows the torque amount according to a speed deviation so that it may become an actual speed according to a speed command. When the brushless motor 10 is subjected to position control, the rotation control unit 41 obtains a position deviation between the rotation command data Dr indicating the position command and the detected position data Dp so that the position conforms to the position command. Rotation control data Dd indicating a torque amount corresponding to the position deviation is generated. The rotation control unit 41 supplies such rotation control data Dd to the drive waveform generation unit 42.

  The drive waveform generator 42 generates a waveform signal Wd for driving the winding 16 for each phase, and supplies the generated waveform signal Wd to the PWM circuit 43. When the winding 16 is driven with a sine wave, the waveform signal Wd is a sine wave signal. When the winding 16 is driven with a rectangular wave, the waveform signal Wd is a rectangular wave signal. The amplitude of the waveform signal Wd is determined according to the rotation control data Dd. The timing for supplying the waveform signal Wd to the PWM circuit 43 is a reference timing for driving the winding 16 based on the waveform signal Wd, and this reference timing is determined according to the phase control data Dtp from the phase control unit 46. Is done.

  A PWM (Pulse Width Modulation) circuit 43 performs pulse width modulation on each waveform signal Wd supplied from the drive waveform generation unit 42 for each phase as a modulation signal. The PWM circuit 43 supplies the drive pulse signal Pd, which is a pulse train signal pulse-width-modulated with the waveform signal Wd as described above, to the inverter 44.

  The inverter 44 energizes the winding 16 for each phase based on the drive pulse signal Pd to drive the winding 16. The inverter 44 includes a switching element connected to the positive side of the power source and a switching element connected to the negative side for each of the U phase, the V phase, and the W phase. Further, the opposite power supply sides of both the positive electrode side and the negative electrode side are connected to each other, and this connection portion becomes a drive output end portion 4 d that drives the winding 16 from the inverter 44. The U-phase drive output end 4du is connected to the winding 16U, the V-phase drive output end 4dv is connected to the winding 16V, and the W-phase drive output end 4dw is connected to the winding 16W via the lead wire 16a. Connected. In each phase, when the switch element is turned on / off by the drive pulse signal Pd, a drive current flows from the drive output end 4d to the winding 16 via the switch element turned on from the power supply. Here, since the drive pulse signal Pd is a signal obtained by performing pulse width modulation on the waveform signal Wd, the respective windings 16 are energized with the drive current corresponding to the waveform signal Wd when the switch elements are turned on and off in this way. Is done.

  With the above-described configuration, a feedback control loop for controlling the rotation speed and rotation position of the rotor 12 according to the rotation command data Dr is formed, and the brushless motor 10 has a motor rotor position detection constituted by the Hall element 38 and the zero cross detection circuit 50. It is rotationally driven by a position detection signal Sp from the device 60.

  Next, the operation of the motor rotor position detection device 60 of the present embodiment will be described in detail. FIG. 5 is a diagram showing the configuration of the motor rotor position detection device 60 of the present embodiment. In FIG. 5, for simplicity of explanation, the permanent magnets 18 arranged along the outer periphery of the rotor 12 have four poles, and three Hall elements 38U, 38V, and 38W as magnetic sensors are opposed to the permanent magnets 18. Will be described as being arranged at an electrical angle of 120 degrees. From the hall elements 38U, 38V, 38W, hall signals are output as magnetic detection signals having a sine waveform having a phase difference of 120 electrical degrees. The hall signal is composed of two-phase signals of normal phase and reverse phase. The hall signals from the hall elements 38U, 38V, and 38W are input to the zero-cross detection circuits 50U, 50V, and 50W, respectively, and the position detection signals Spu, Spv, and Spw are output. The zero-cross detection circuits 50U, 50V, and 50W are provided with hysteresis characteristics to prevent chattering. Since the Hall elements 38U, 38V, and 38W perform the same position detection operation, the operation of the motor rotor position detection device 60 will be described using the Hall element 38U as an example.

  FIG. 6 is a diagram illustrating a position detection operation of the motor rotor position detection device 60 according to the first embodiment of the present invention. 6A shows the signal waveform of the Hall signal U, FIG. 6B shows the time variation of the threshold value of the zero-cross detection circuit 50U, and FIG. 6C shows the position detection signal Spu output from the zero-cross detection circuit 50U. In FIG. 5, when the rotor 12 makes one revolution, the Hall element 38U detects the magnetic field from the permanent magnet 18 in the order of N pole → S pole → N pole → S pole, and as shown in FIG. Hall signal U (U = (U +) − (U−)) is generated. In the zero-cross detection circuit 50U, a first threshold Th0, a second threshold Th1 that is smaller than the first threshold, and a third threshold Th2 that is larger than the first threshold are set. The first threshold Th0 can be set to an arbitrary voltage, but here, the threshold Th0 will be described as 0 (V) for the sake of simplicity. The threshold value Th1 and the threshold value Th2 are desirably set to be larger than the maximum amplitude of noise superimposed on the hall signal U. This is for reliably preventing chattering of the zero cross detection circuit. First, the threshold Th of the zero cross detection circuit 50U is set to 0 (V). At the timing (time T0) at which the rotor 12 rotates and the detection point of the hall element 38U passes from the north pole 18d to the south pole 18a and the amplitude of the hall signal U increases from the negative peak of the sine wave to zero cross. The detection signal Spu changes from L (low level) to H (high level). At the same time, the threshold Th is switched to the negative threshold Th1. At this time, since the amplitude of the Hall signal U changes in an increasing direction, even if noise is superimposed, it does not fall below the threshold value Th1, and chattering does not occur. Thereafter, the W-phase hall signal W advanced by 120 degrees from the U-phase returns the threshold value Th to 0 (V) at time T0w when the first zero crossing occurs after time T0. Time T0w is a time delayed by a time corresponding to 60 degrees in electrical angle from time T0.

  Next, at the timing (time T1) at which the detection point of the Hall element 38U passes from the S pole 18a to the N pole 18b and the amplitude of the Hall signal U decreases from the positive peak of the sine wave to zero cross (time T1). Changes from H to L. At the same time, the threshold Th of the zero cross detection circuit 50U is switched to the positive threshold Th2. At this time, since the amplitude of the Hall signal U changes in a decreasing direction, even if noise is superimposed, the threshold Th2 is not exceeded and chattering does not occur. Thereafter, the threshold Th is returned to 0 (V) at the timing (time T1w) when the W-phase hall signal W crosses zero. The time T1w is a time delayed by a time corresponding to 60 degrees in electrical angle from the time T1. Thereafter, this operation is repeated. The timing at which the threshold value Th is returned to 0 (V) may be the time T0v or T1v at which the V-phase hall signal V delayed by 120 degrees from the U-phase is zero-crossed. In order to follow the change as soon as possible, it is preferable to use the W phase.

  As described above, according to the motor rotor position detection device 60 of the present embodiment, the rotation position of the rotor 12 can be detected at the zero cross timing of the hall signal U, and the threshold value of the zero cross detection circuit 50 has a hysteresis characteristic. It is possible to prevent chattering. Thereby, the exact rotation position of the rotor 12 can be detected, the accuracy of the rotation control of the rotor 12 can be increased, and the high efficiency of the brushless motor 10 can be maintained. In addition, since the threshold value Th is returned to 0 (V) at the zero cross timing of the hall signal of the other phase, the threshold value Th is reliably returned to 0 (V) even if the rotation speed or the rotation direction of the rotor 12 changes. Thus, the rotational position of the rotor 12 can be reliably detected. Further, since it is not necessary to create a special timing signal for returning the threshold Th to 0 (V), the circuit configuration can be simplified.

(Embodiment 2)
Next, the motor rotor position detection device 60 according to the second embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the first embodiment only in the timing generation method for returning the threshold value Th to 0 (V), and the rest is the same as in the first embodiment, and the description of the overlapping parts is omitted. To do.

  FIG. 7 is a diagram for explaining the position detection operation of the motor rotor position detection device 60 according to the second embodiment of the present invention. As shown in FIG. 7, in the present embodiment, the threshold value Th of the zero-cross detection circuit 50U is first set to 0 (V). At the timing (time T0) when the amplitude of the Hall signal U increases from the negative peak of the sine wave and zero-crosses (time T0), the threshold Th is switched to the negative threshold Th1. At this time, since the amplitude of the Hall signal U changes in an increasing direction, even if noise is superimposed, it does not fall below the threshold value Th1, and chattering does not occur. Thereafter, the threshold value Th is returned to 0 (V) at time T02. Time T02 is a time delayed by a predetermined time tq set in advance from time T0. The predetermined time tq is preferably set to be longer than the time tp from the time T0 to the time T01 when the hall signal U crosses the positive threshold Th2, and is equal to or less than ½ of the period of the hall signal U. By setting in this way, chattering can be reliably prevented after the threshold Th is returned to 0 (V). Further, since the time tp varies depending on the rotation speed of the rotor 12, it is desirable to change tq so as to satisfy the relationship of tq> tp in conjunction with the rotation speed of the rotor 12. For this, a correspondence table of the rotation speed (rotation cycle) and the predetermined time tq is prepared in advance, and when the rotation speed changes, the predetermined time tq may be determined with reference to this table. Further, since the time tp also changes due to the change in the amplitude of the Hall signal U, the predetermined time tp may be corrected according to this amplitude.

  Next, at the timing (time T1) when the amplitude of the Hall signal U decreases from the positive peak of the sine wave and zero-crosses (time T1), the threshold value Th of the zero-cross detection circuit 50U is switched to the positive-side threshold value Th2. At this time, since the amplitude of the Hall signal U changes in a decreasing direction, even if noise is superimposed, the threshold Th2 is not exceeded and chattering does not occur. Thereafter, the threshold value Th is returned to 0 (V) at time T12. Time T12 is a time delayed by a predetermined time tq set in advance from time T1.

  As described above, according to the motor rotor position detection device 60 of the present embodiment, the rotation position of the rotor 12 can be detected at the zero cross timing of the hall signal U, and the threshold value of the zero cross detection circuit 50 has a hysteresis characteristic. It is possible to prevent chattering. Thereby, the exact rotation position of the rotor 12 can be detected, the accuracy of the rotation control of the rotor 12 can be increased, and the high efficiency of the brushless motor 10 can be maintained. Further, since the threshold value Th is returned to 0 (V) after a predetermined time set in advance from the time point of zero cross detection, the Hall signal of the other phase is not necessary, and can be applied to the case where there is one Hall element. Even when the rotation direction of the rotor 12 changes, no special control is required.

(Embodiment 3)
Next, a motor rotor position detection device 60 according to Embodiment 3 of the present invention will be described with reference to FIG. The difference between the present embodiment and the first embodiment is only the timing generation method for returning the threshold value Th to 0 (V), and the others are the same as those of the first embodiment, so that the overlapping parts are described. Is omitted.

  FIG. 8 is a diagram for explaining the position detection operation of the motor rotor position detection device 60 according to the third embodiment of the present invention. As shown in FIG. 8, in the present embodiment, the threshold value Th of the zero-cross detection circuit 50U is first set to 0 (V). At the timing (time T0) when the amplitude of the Hall signal U increases from the negative peak of the sine wave and zero-crosses (time T0), the threshold Th is switched to the negative threshold Th1. At this time, since the amplitude of the Hall signal U changes in an increasing direction, even if noise is superimposed, it does not fall below the threshold value Th1, and chattering does not occur. Thereafter, the threshold value Th is returned to 0 (V) at time T01. The time T01 is a time at which the hall signal U crosses the positive threshold Th2, and then the hall signal U becomes larger than the threshold Th2, so that chattering is reliably prevented after the threshold Th returns to 0 (V). can do.

  Next, at the timing (time T1) when the amplitude of the Hall signal U decreases from the positive peak of the sine wave and zero-crosses (time T1), the threshold value Th of the zero-cross detection circuit 50U is switched to the positive-side threshold value Th2. At this time, since the amplitude of the Hall signal U changes in a decreasing direction, even if noise is superimposed, the threshold Th2 is not exceeded and chattering does not occur. Thereafter, the threshold value Th is returned to 0 (V) at time T11. Time T11 is a time at which the Hall signal U crosses the negative threshold Th1, and then the Hall signal U becomes smaller than the threshold Th1, so that chattering can be reliably prevented after the threshold Th is returned to 0V. it can.

  As described above, according to the motor rotor position detection device 60 of the present embodiment, the rotation position of the rotor 12 can be detected at the zero cross timing of the hall signal U, and the threshold value of the zero cross detection circuit 50 has a hysteresis characteristic. It is possible to prevent chattering. Thereby, the exact rotation position of the rotor 12 can be detected, the accuracy of the rotation control of the rotor 12 can be increased, and the high efficiency of the brushless motor 10 can be maintained. In addition, since the threshold value Th is returned to 0 (V) with the positive threshold value Th2 or the negative threshold value Th1, the Hall signal of the other phase is unnecessary, and can be applied even when there is one Hall element. is there. Even when the rotation direction of the rotor 12 changes, no special control is required. Further, no special circuit for returning the threshold value to 0 (V) is required, so that the circuit can be simplified and the cost can be reduced.

  As described above, according to the motor position detection apparatus of the present invention, the zero detection timing of the Hall signal can be used for position detection, and the occurrence of chattering can be prevented by providing the threshold with hysteresis characteristics. As a result, the accurate rotational position of the rotor can be detected and the accuracy of the rotor rotation control can be increased, so that high efficiency of the motor can be maintained. In addition, it is possible to suppress changes in efficiency especially at high temperatures, and to improve motor characteristics. Furthermore, since consideration for the output amplitude of the Hall signal can be relaxed, the Hall element current can be reduced, the current capability of the peripheral circuit can be reduced, and the distance conditions with the field permanent magnet can be relaxed.

  In the above embodiment, the center threshold value of the zero-cross detection circuit 50 has been described as 0 (V), but the center threshold value may be any voltage. The threshold Th1 and the threshold Th2 may be set with substantially the same voltage difference above and below the central threshold.

  In addition, the three methods described in the first to third embodiments may be combined, and the threshold may be returned to 0 (V) using the earliest timing at which the threshold Th is returned to 0 (V). .

  In the above embodiment, the Hall element 38 detects the magnetic field of the field permanent magnet disposed in the rotor 12. However, another magnet (sub magnet) may be disposed for detecting the rotational position. Good.

  In the above-described embodiment, the brushless motor including the 8-pole 12-slot rotor has been described as an example. However, the present invention is not limited to this structure. The present invention can be applied not only to detecting the rotational position of the rotor of a rotary motor in which the mover rotates, but also to detecting the position of the mover of a linear motor in which the mover moves linearly.

  In the third embodiment, the timing at which the threshold is returned to the first threshold Th0 is the timing at which the Hall signal U crosses the second threshold Th1 and the third threshold Th2, but the second and third Instead of the threshold value, new fourth and fifth threshold values may be set.

  The motor position detection device of the present invention and the motor using the motor can accurately detect the rotational position of the rotor even when the amplitude of the detection signal of the Hall element changes due to temperature and element variations. It can be widely applied to motors that require high output and high efficiency, such as electronic components.

4d Drive output end 10 Brushless motor 11 Stator 12 Rotor 13 Circuit board 14 Motor case 15 Stator core 15a Yoke 15b Teeth 16, 16U, 16V, 16W Winding 16a Lead wire 17 Rotor frame 18 Permanent magnet 19 Bearing 20 Rotating shaft 21 Support Member 31 Circuit parts 38, 38U, 38V, 38W Hall element 40 Drive control circuit 41 Rotation control unit 42 Drive waveform generation unit 43 PWM circuit 44 Inverter 45 Position data generation unit 46 Phase control unit 50, 50U, 50V, 50W Zero cross detection circuit 60 Motor rotor position detection device

Claims (5)

A stator,
A motor position detection device comprising: a mover arranged opposite to the stator and having at least a pair of N-pole and S-pole permanent magnets arranged alternately along the moving direction;
A magnetic sensor for detecting a magnetic field from the permanent magnet and outputting a sinusoidal magnetic detection signal;
A first threshold value; a second threshold value that is smaller than the first threshold value; and a third threshold value that is greater than the first threshold value, the magnetic detection signal being compared with the threshold value, A zero-cross detection circuit that outputs a position detection signal indicating the position,
The zero cross detection circuit switches the threshold to the second threshold at a timing when the magnetic detection signal increases and crosses the first threshold in a state where the first threshold is set. Return to the first threshold at the timing,
A motor position, wherein the threshold value is returned to the first threshold value at a predetermined timing after the threshold value is switched to the third threshold value at a timing when the magnetic detection signal decreases and crosses the first threshold value. Detection device. The motor is a rotary three-phase motor, and the predetermined timing for returning the threshold value to the first threshold value is a timing at which the magnetic detection signal of another phase crosses the first threshold value. The motor position detection apparatus according to claim 1, wherein The predetermined timing for returning the threshold value to the first threshold value is a timing delayed by a predetermined time from a timing at which the magnetic detection signal crosses the first threshold value. Item 2. The motor position detection device according to Item 1. The predetermined timing for returning the threshold value to the first threshold value is a timing that crosses the third threshold value when the magnetic detection signal is increased, and the magnetic detection signal is decreased. 2. The motor position detection apparatus according to claim 1, wherein the timing is a timing crossing the second threshold value. A motor comprising the motor position detection device according to claim 1.

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