JP2013031275A - Rotation characteristic detection device and driving characteristic inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor rotation characteristic detection device capable of detecting a rotation number in a non-contact manner with a DC brushless motor without coupling a gear and the like to an output axis of the DC brushless motor while eliminating a need for modification to a driving circuit.SOLUTION: A rotation characteristic detection device has: at least one of detectors 11-14 arranged in a magnetic field respectively generated by a plurality of excitation coils configuring a stator of a DC brushless motor that is an inspected target, and inducing a voltage depending on a change of the magnetic field; and a cycle measurement part 15 measuring a variation cycle of a voltage generated at both ends of each detector 11-14.

Description

  The present invention relates to a rotation characteristic detection device and a drive characteristic inspection device, and more particularly to a rotation characteristic detection device capable of measuring a rotation characteristic in a non-contact state with a DC brushless motor and a drive characteristic inspection of a DC brushless motor using the rotation characteristic detection device. Relates to the device.

  In recent years, DC brushless motors having no commutator have been widely used in the field of DC motors from the viewpoints of reliability and maintainability.

  In order to apply such a DC brushless motor to a drive source such as a hard disk for a computer or a server, it is necessary that the rotation characteristic value including the rotation unevenness of the DC brushless motor itself is not more than a predetermined reference value. Therefore, it is necessary to inspect the rotational characteristics of the DC brushless motor alone.

  Conventionally, electromagnetic pickups, optical interrupters, tachometers, and the like are well known as motor rotation speed measurement sensors.

  However, in order to apply electromagnetic pickups and optical interrupters, it is necessary to install gears on the motor shaft. To apply tachometers, it is necessary to combine the motor shaft and the tachometer generator. It is impossible to avoid the effects of gears and tacho generators.

  An optical stroboscope is also known as a device that can measure the rotation speed of a motor without contact.

  However, the optical stroboscope needs to apply a reflective tape to the rotating shaft of the motor, but it is difficult to apply the reflective tape in a situation where the motor itself is downsized.

  Furthermore, in order to automatically determine whether or not synchronization is established, complicated processing such as image processing is required, and application to an automatic inspection apparatus becomes difficult.

  Therefore, focusing on the fact that a drive circuit is essential in a DC brushless motor, the DC brushless motor itself is based on the logical product of the drive pulse output from the drive circuit and the voltage induced in the coil of the DC brushless motor. Has already been proposed for detecting the rotational speed in a non-contact manner (see, for example, Patent Document 1).

JP 2004-173360 A

  However, the invention described in Patent Document 1 has a problem that it is necessary to modify the drive circuit in order to draw the detection line from the drive circuit when measuring the rotation characteristics of the motor.

  The present invention has been made in view of the above-described problems, and it is not only unnecessary to modify the drive circuit, but is not different from a DC brushless motor without coupling a gear or the like to the output shaft of the DC brushless motor. An object of the present invention is to provide a motor rotation characteristic detection device capable of detecting the rotation speed by contact.

  In this specification, the DC brushless motor means all DC motors that do not have a commutator, and not only a narrowly defined DC brushless motor that forms a rotor with a permanent magnet, but also a switch that forms a rotor with a magnetic material. A reluctance motor (SRM) is also included.

  The rotational characteristic detection device according to the present invention is arranged in a magnetic field generated by each of a plurality of exciting coils constituting a stator of a DC brushless motor to be inspected, and at least induces a voltage according to a change in the magnetic field. It has a configuration including one detection unit 11 to 14 and a period measurement unit 15 that measures a fluctuation period of a voltage generated at both ends of the detection units 11 to 14.

  With the above configuration, the rotational speed of the DC brushless motor can be detected without contact with the DC brushless motor itself.

  The rotational characteristic detection apparatus according to the present invention has a configuration including a total voltage measurement unit that measures a total value of voltages generated at both ends of the detection units 11 to 14.

  With the above configuration, rotation unevenness of the DC brushless motor can be detected.

  In the rotation characteristic detection device according to the present invention, the detection units 11 to 14 have iron cores 11a to 14a arranged in a magnetic field generated by the excitation coil, and detection coils 11b to 14b wound around the iron cores 11a to 14a. And.

  In the rotation characteristic detection apparatus according to the present invention, the detection units 11 to 14 further include amplification units 11d to 14d that amplify voltages generated at both ends of the detection coils 11b to 14b.

  The drive characteristic detection apparatus according to the present invention is connected to a rotation characteristic detection apparatus 1 that detects the number of rotations of a DC brushless motor to be inspected, an input shaft connected to the output shaft of the DC brushless motor, and a stationary object. A powder brake 35 having an output shaft, a torque detector 36 for detecting torque generated on the output shaft of the powder brake 35, and a current value flowing through the exciting coil of the DC brushless motor while supplying driving power to the DC brushless motor , A driving force control unit 373 for controlling the braking force generated by the powder brake 35, a torque measuring unit 374 for measuring the output torque generated by the DC brushless motor from the output of the torque detecting unit 36, The rotational speed of the DC brushless motor output from the rotation characteristic detection device 1 and the excitation coil output from the drive unit 372 The current flowing, and a driving characteristic inspection unit 375 for detecting the driving characteristic of the DC brushless motor based on the output torque output from the torque measuring unit 374, a.

  According to the rotational characteristic detection device according to the present invention, measurement can be performed completely in a non-contact manner with the DC brushless motor main body, so that the rotational characteristic of the DC brushless motor itself can be accurately detected.

It is the upper side figure (a) and YY sectional drawing (b) of the DC brushless motor which equipped with the rotational characteristic detection apparatus based on this invention. It is a structural diagram of the detection part of the rotation characteristic detection apparatus which concerns on this invention. It is a wiring diagram of the measurement part corresponding to a detection coil, an amplification part, and an amplification part. It is a wave form diagram of an exciting coil and an amplification part. It is a wave form diagram of the voltage output from the detection part input into a measurement part, and a total voltage. It is a block diagram at the time of applying this invention to the DC brushless motor of 3 poles of 2 phase excitation. It is the schematic of the drive characteristic test | inspection apparatus of the DC brushless motor to which the rotation characteristic detection apparatus based on this invention is applied.

  FIG. 1 is a top view (a) and a YY sectional view (b) of a DC brushless motor 2 to be inspected, to which a rotational characteristic detection device 1 according to the present invention is attached.

  In the present embodiment, the DC brushless motor 2 to be inspected is composed of a stator 20 composed of four exciting coils 21 to 22 arranged every 90 degrees around a rotating shaft and a rotor 25 in which permanent magnets are embedded. Shall be.

  The rotational characteristic detection device 1 according to the present invention has four detection units 11 to 14 arranged corresponding to the respective excitation coils 21 to 24, and fluctuation periods of voltages induced at both ends of the detection units 11 to 14. A period measuring unit 15 for measuring.

  The detectors 11 to 14 need to be arranged in the magnetic field generated by each of the exciting coils 21 to 24 of the DC brushless motor 2, and are arranged close to the DC brushless motor 2.

  FIG. 2 is a structural diagram of the detection unit 11 which is one of the detection units 11 to 14 of the rotation characteristic detection device 1 according to the present invention, and a corresponding excitation coil 21 is also appended.

  In the present embodiment, the detection unit 11 includes an I-shaped iron core 11a and a detection coil 11b wound around the iron core 11a. The outer periphery of the detection coil 11b is covered with a magnetic shield material 11c.

  In the rotation characteristic detection device 1 according to the present invention, the detection unit 11 is arranged so that the iron core 11a is orthogonal to the magnetic field lines generated by the excitation coil 21 of the DC brushless motor 2.

  Furthermore, in the present embodiment, the detection unit 11 also includes an amplification unit 11d that amplifies the voltage induced in the detection coil 11b and generates a pulse signal.

  The pulse signal output from the amplifying unit 11d is guided to a frequency meter included in the period measuring unit 15, and displays the frequency of the pulse signal as the rotation speed of the DC brushless motor 2.

  FIG. 3 is a wiring diagram of the detection coil 11b, the amplification unit 11d, and the period measurement unit 15 corresponding to the amplification unit 11d. One end of the detection coil 11b is connected to one input terminal of the amplifier 112 via the coupling capacitor 111. ing. The output of the amplifier 112 is connected to one input terminal of the comparator 113.

  The coupling capacitor 111 is for removing the DC component of the voltage across the detection coil. The other end of the detection coil 11b, the other input terminal of the amplifier 112, and the other input terminal of the comparator 113 are connected to a common ground. It is connected to the.

  FIG. 4 is a waveform diagram of the excitation coil and the amplifying unit. The excitation voltage waveform (A) applied to the excitation coil, the current waveform (B) flowing through the excitation coil, the rotor side polarity (C) of the excitation coil, and the detection A voltage waveform (d) induced in the coil and a pulse signal waveform (e) output from the amplifying unit are shown.

  That is, when a pulsed excitation voltage (A) is applied to the excitation coil 21, an excitation current (B) that flows at the maximum when the excitation voltage rises and becomes the minimum when the excitation voltage falls flows through the excitation coil 21. The rotor side end of the excitation coil 21 is alternately excited (c) to the S and N poles.

  Since the detection coil 11b is disposed in the magnetic field generated by the excitation coil 21, a voltage (d) in phase with the excitation current flowing through the excitation coil 21 is induced at both ends of the detection coil 11b.

  This induced voltage is amplified by about 100 times (40 decibels) in the amplifier d2 and supplied to one input terminal of the comparator d3.

  The comparator d3 compares the voltage induced in the detection coil 11b with the ground voltage and outputs a pulse signal (e).

  The period measurement unit 15 includes a frequency meter 151, measures the frequency of the pulse signal output from the amplification unit 11d, and outputs the measured frequency as the rotation speed of the DC brushless motor 2.

  Note that the period measuring unit 15 also includes a power source 152, and supplies driving power (for example, 24 VDC) to the amplifier d2 and the comparator d3 of the amplifying unit 11d.

  Here, in FIG. 4, it has been described that one period measuring unit 15 is provided corresponding to one detecting unit 11, but one period measuring unit 15 is provided for the four detecting units 11 to 14, and the switch In this case, the detection unit may be selected.

  Furthermore, if the physical configuration of the DC brushless motor 2 is the same for each excitation phase, the total voltage obtained by adding the voltages induced in the detection coils 11b to 14b in the same phase should be zero.

  Therefore, by measuring the total voltage obtained by adding the voltages induced in the detection coils 11b to 14b in the same phase, it is possible to detect a physical configuration difference between the excitation phases of the DC brushless motor 2 as rotation unevenness.

  Various factors can be considered as the difference in the physical configuration between the excitation phases of the DC brushless motor 2. For example, bending of the rotor spindle, imbalance of the permanent magnets constituting the rotor, disconnection of the excitation coil, etc. are assumed. can do.

  FIG. 5 shows voltage waveforms and total voltage waveforms output from the detection units 11 to 14 that are input to the period measurement unit 15 of the rotational characteristic detection device 1 shown in FIG. 1, and are output from the detection units 11 to 14. In the case of two-pole excitation, the voltages induced in the A phase and the C phase are in phase, and the voltages induced in the B phase and the D phase are in reverse phase.

  Therefore, the total voltage of the voltages induced in the detection coils 11 to 14 is theoretically zero, and actually has fluctuations due to rotation unevenness of the DC brushless motor 2.

  Therefore, whether or not the DC brushless motor 2 is assembled with a predetermined accuracy by detecting whether or not the total voltage of the voltages induced in the detection coils 11 to 14 is within a predetermined upper limit value and lower limit value range. It becomes possible to evaluate whether or not.

  Although the case where a four-pole DC brushless motor is two-phase excited has been described above, the present invention can be applied to other types of DC brushless motors.

  FIG. 6 is a configuration diagram when the present invention is applied to a two-phase excitation three-pole DC brushless motor, and three detection units are used corresponding to the three excitation coils of the DC brushless motor.

  FIG. 7 is a schematic diagram of a DC brushless motor drive characteristic inspection apparatus 3 to which the rotational characteristic detection apparatus according to the present invention is applied. One side plate of the concave substrate 30 is detected by the rotational characteristic detection apparatus according to the present invention. Part 31 is attached.

  A DC brushless motor 32 to be inspected is installed on the motor fixing block 33 with a predetermined distance from the detection unit 31.

  The output shaft of the DC brushless motor 32 is connected to the input shaft of the powder brake 35 via the joint 34.

  The output shaft of the powder brake 35 is fixed to the other side plate of the concave substrate 30. A torque detector 36 for detecting torque transmitted to the output shaft is attached to the output shaft of the powder brake 35.

  The drive characteristic inspection device 3 further includes a control measurement unit 37.

  The control measurement unit 37 measures the rotation number of the DC brushless motor 32 to be inspected based on the output of the detection unit 31, the drive unit 372 that supplies drive power to the DC brushless motor 32, and the powder brake 35. A braking force control unit 273 that controls power, a torque measurement unit 374 that measures torque generated by a DC brushless motor based on the output of the torque detection unit 36, a measurement unit 371, a drive unit 372, a braking force control unit 373, and torque It comprises a drive characteristic inspection unit 375 that controls the measurement unit 374 and inspects the drive characteristic of the DC brushless motor 32.

  When the DC brushless motor 32 is inspected using the drive characteristic inspection device 3 having the above-described configuration, the DC brushless motor 32 is rotated by outputting an excitation voltage of a predetermined frequency from the drive unit 372 to detect the rotation characteristic according to the present invention. The actual number of revolutions is detected by the device.

  A voltage corresponding to a predetermined load is supplied from the braking force control unit 373 to the powder brake 35, and a load is applied to the brushless motor 32 by controlling the density of the magnetic fluid in the powder brake 35.

  Then, the output torque of the DC brushless motor 32 is detected from the output of the torque measuring unit 374.

  Since the drive unit 372 also outputs an excitation current value, the rotational speed, excitation current, and output torque of the DC brushless motor 32 can be detected at the same time, and the drive characteristics of the DC brushless motor 32 can be inspected.

  As described above, the rotational characteristic detection device according to the present invention can measure the rotational speed without contact with the DC brushless motor itself, and is useful for detecting the rotational characteristic and driving characteristic of the DC brushless motor. is there.

DESCRIPTION OF SYMBOLS 1 Rotation characteristic detection apparatus 2 DC brushless motor 3 Drive characteristic inspection apparatus 11-14 Detection part 11a-14a Iron core 11b-14b Detection coil 11c-14c Magnetic shield material 11d-14d Amplification part 15 Period measurement part 20 Stator 21-24 Excitation Coil 25 Rotor 30 Substrate 31 Detection unit 32 DC brushless motor 33 Motor fixed block 34 Joint 35 Powder brake 36 Torque detection unit 37 Control measurement unit 111 Coupling capacitor 112 Amplifier 113 Comparator 151 Frequency meter 152 Power supply 371 Measurement unit 372 Drive unit 373 Control Power control unit 374 Torque measurement unit 375 Drive characteristic inspection unit

Claims (5)

At least one detector that is arranged in a magnetic field generated by each of a plurality of exciting coils constituting a stator of a DC brushless motor to be inspected and induces a voltage in accordance with a change in the magnetic field;
A rotation characteristic detecting device including a period measuring unit that measures a fluctuation period of a voltage generated at both ends of the detecting unit.   The rotational characteristic detection apparatus according to claim 1, further comprising a total voltage measurement unit that measures a total value of voltages generated at both ends of the detection unit. An iron core disposed in the magnetic field generated by the excitation coil,
The rotation characteristic detection device according to claim 1 or 2, comprising a detection coil wound around the iron core.   The rotational characteristic detection device according to claim 3, wherein the detection unit further includes an amplification unit that amplifies a voltage generated at both ends of the detection coil. The rotational characteristic detection device according to any one of claims 1 to 4, wherein the rotational speed of a DC brushless motor to be inspected is detected.
A powder brake comprising: an input shaft connected to the output shaft of the DC brushless motor; and an output shaft connected to a stationary object;
A torque detector for detecting torque generated on the output shaft of the powder brake;
A driving unit that supplies driving power to the DC brushless motor and outputs a current value flowing through an excitation coil of the DC brushless motor;
A braking force control unit for controlling a braking force generated by the powder brake;
A torque measuring unit for measuring an output torque generated by the DC brushless motor from an output of the torque detecting unit;
The DC brushless motor based on the rotational speed of the DC brushless motor output from the rotation characteristic detection device, the current value flowing through the excitation coil output from the drive unit, and the output torque output from the torque measurement unit. And a drive characteristic inspection unit that detects the drive characteristic of the drive characteristic inspection device.

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