JP2009261122A - Motor drive device and servo motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive device and a servo motor capable of achieving reductions in size and weight. <P>SOLUTION: The motor drive device includes a motor drive part 44 that has a bridge circuit for switching excitation of each phase coil, and a power circuit part 45 that is connected with an external power supply and that supplies current to the motor drive part 44. The power circuit part 45 is a drive device 7 that is configured to supply a prescribed current to the motor drive part 44 at a prescribed excitation switching timing based on a control signal of an external control device. The motor drive part 44 is mounted on an annular first rigid substrate 41 into which a rotation shaft can be inserted, the power circuit part 45 is mounted on an annular second rigid substrate 42 into which the rotation shaft can be inserted, and the first rigid substrate 41 and the second rigid substrate 42 are connected through a flexible substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor drive device and a servomotor using the same.

In general, a motor drive device that drives a servo motor is energized according to the rotation angle of the rotation shaft of the servo motor, a motor drive unit that energizes the servo motor, a power supply circuit unit that supplies external power to the motor drive unit, and the like. And a control unit for controlling the switching timing.
Here, a rotation angle detection device for detecting the rotation angle of the rotation shaft is provided at one end of the motor case of the servo motor, and a motor drive device is disposed on the end surface opposite to the servo motor of the rotation angle detection device. There is what I did. With this configuration, the servo motor, the rotation angle detection device, and the motor drive device are integrated to reduce the size and weight of the entire servo motor system (see, for example, Patent Document 1 and Patent Document 2). ).
JP 2004-201415 A JP 2004-208415 A

  However, in the above-described prior art, since the rotation angle detection device and the motor drive device are simply arranged at one end of the motor case, the servo shaft as a whole increases the motor shaft length, The diameter increases. For this reason, there exists a subject that the layout property of a servomotor deteriorates.

  Therefore, the present invention has been made in view of the above-described circumstances, and provides a motor drive device and a servo motor that can be further reduced in size and weight.

In order to solve the above problems, the invention described in claim 1 is directed to a motor drive unit having a bridge circuit for switching energization to the coils of each phase, and an external power source connected to supply current to the motor drive unit. A motor driving device configured to supply a predetermined current to the motor driving unit at a predetermined energization switching timing based on a control signal of an external control device. The motor drive unit is mounted on an annular first rigid board through which the motor shaft can be inserted, and the power supply circuit unit is mounted on an annular second rigid board through which the motor shaft can be inserted. One rigid board and the second rigid board are connected via a flexible board.
With this configuration, the first rigid board on which the motor drive unit is mounted and the second rigid board on which the power supply circuit unit is mounted are surrounded by the motor shaft within each shaft end of the motor shaft. It becomes possible to arrange.

According to a second aspect of the present invention, a rotation angle detection device for detecting a rotation angle of the motor shaft is provided in the power supply circuit unit, and the external control device is energized based on a detection result of the rotation angle detection device. The switching timing is determined.
With this configuration, it is not necessary to separately provide a rotation angle detection device for detecting the rotation angle of the motor shaft, and the rotation angle detection device and the motor drive device can be integrated. For this reason, the space occupied by the rotation angle detection device can be reduced.

According to a third aspect of the present invention, the motor drive device according to the first or second aspect is provided on one end side of the motor housing, and the flexible substrate is curved to form the first rigid substrate and the second rigid substrate. And a servo motor characterized by being arranged opposite to each other.
With this configuration, a small and lightweight servo motor can be provided.

  According to the first aspect of the present invention, the motor shaft is mounted in each shaft end of the motor shaft by connecting the first rigid substrate on which the motor drive unit is mounted and the second rigid substrate on which the power supply circuit unit is mounted. It becomes possible to arrange so that it may surround. For this reason, even if it is a case where a motor drive device is arrange | positioned at the one end side of a servomotor, motor shaft length can be shortened conventionally.

  According to the invention described in claim 2, it is not necessary to separately provide a rotation angle detection device for detecting the rotation angle of the motor shaft, and the rotation angle detection device and the motor drive device can be integrated. For this reason, the space occupied by the rotation angle detection device can be reduced. Therefore, it is possible to reduce the size of the entire motor.

  According to the invention described in claim 3, it is possible to provide a small and lightweight servo motor.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the servo motor 1 includes a cylindrical housing 2, a stator 3 fitted and fixed to the housing 2, and a rotor provided to be rotatable with respect to the stator 3. 4, the front end surface of the housing 2 (the left end in FIGS. 1 and 2) is closed by the front bracket 5, and the rear end surface of the housing 2 (the right end in FIGS. 1 and 2) is closed by the end bracket 6. Blocked. A driving device 7 for driving the servo motor 1 is provided on the end bracket 6 side of the rotor 4.

  On the outer peripheral surface of the housing 2, a reduced diameter portion 15 having a diameter reduced by a step is formed on the peripheral edge on the front bracket 5 side, while an enlarged diameter portion 17 having a diameter increased by a step on the peripheral edge on the end bracket 6 side. Is formed.

  The stator 3 is formed by laminating plate materials of magnetic material in the axial direction or pressurizing magnetic metal powder (powder magnetic core). The stator core 8 has a substantially cylindrical shape. Have. The stator core 8 is formed by integrally molding a core main body 9 that forms a peripheral wall and a plurality of teeth portions 10 that project from the core main body 9 inward in the radial direction.

The core body 9 is a portion that forms an annular magnetic path of the stator core 8 and is a portion that is fitted and fixed to the inner peripheral surface of the housing 2.
On the other hand, each teeth part 10 is a part which winds the coil | winding 11, Comprising: It is provided in the circumferential direction at equal intervals. The teeth portion 10 is formed in a substantially T shape in an axial direction plan view. Each tooth portion 10 is provided with an insulator 12, and a winding 11 is wound around each tooth portion 10 via the insulator 12.

  The rotor 4 includes a rotating shaft 13 and a substantially cylindrical ring magnet 14 that is externally fixed to the rotating shaft 13. A sensor magnet 28 is provided at one end of the rotating shaft 13 via an attachment member 26. The sensor magnet 28 constitutes one of the encoders 30 for detecting the rotation angle of the rotary shaft 13 and is magnetized in two poles. The mounting member 26 is formed by integrally molding a cylindrical portion 26a on which the rotary shaft 13 is fitted and fixed, and an outer flange portion 26b provided at the outer end of the cylindrical portion 26a. The outer flange portion 26b is for positioning the sensor magnet 28 in the axial direction. The sensor magnet 28 is fixed such that one end surface thereof is in contact with the outer flange portion 26b.

  The ring magnet 14 is magnetized so that the magnetic poles change in order in the circumferential direction. Under such a configuration, when a current flows through the winding 11 wound around the tooth portion 10 of the stator 3, a magnetic field is formed, and a magnetic attractive force generated between the magnetic field and the ring magnet 14. The rotating shaft 13 rotates due to the repulsive force.

The front bracket 5 is formed in a substantially disc shape, and is provided with a fitting portion 20 that fits into the reduced diameter portion 15 of the housing 2 on the outer peripheral edge.
The front bracket 5 is provided with female screw portions 21 at equal intervals in the circumferential direction (see FIG. 1). A bearing housing 23 is formed in the center of the front bracket 5 in the radial direction, and a bearing 22 for rotatably supporting the other end of the rotating shaft 13 is provided here.

  The end bracket 6 is formed in a substantially disk shape, and is provided with a cylindrical portion 27 formed so as to rise inward on the outer peripheral portion. An inlay portion 31 is formed at the tip of the cylindrical portion 27 so as to correspond to the enlarged diameter portion 17 of the housing 2. The end bracket 6 is positioned by fitting the inlay portion 31 into the housing 2.

  A bolt hole (not shown) is formed in a portion corresponding to the female screw portion 21 of the front bracket 5 on the inner side of the cylindrical portion 27 of the end bracket 6. The end bracket 6 and the front bracket 5 are fastened and fixed in such a manner that the housing 2 is sandwiched by inserting the bolt 18 from the bolt hole side and screwing it into the female screw portion 21.

A bearing housing 33 is formed at the center in the radial direction of the end bracket 6, and a bearing 34 for rotatably supporting one end side of the rotating shaft 13 is provided here.
Further, an opening 35 for routing a flexible substrate 43 of the driving device 7 to be described later is formed near the outer periphery of the end bracket 6.

As shown in FIGS. 2 to 6, the driving device 7 includes a first rigid substrate 41 made of a hard material such as glass epoxy formed in a substantially annular shape, and an annular portion 42 a and a rectangular portion 42 b that are integrally molded. It has the 2nd rigid board | substrate 42 which consists of hard materials, such as an epoxy, and the flexible substrate 43 which can connect these rigid boards 41 and 42.
3 and 4 are plan views of the driving device 7. FIG. 3 shows the configuration of the front surface, and FIG. 4 shows the configuration of the back surface.

The first rigid substrate 41 is disposed in each axial end of the rotating shaft 13 and on the inner side in the axial direction from the end bracket 6, and each winding 11 wound around the tooth portion 10 of the stator 3. Terminal portions (winding start end and winding end end) 11a are connected. That is, the diameter of the hole 37 formed in the center in the radial direction of the first rigid board 41 is set to a size that allows the rotation shaft 13 to be inserted, and the outer diameter of the first rigid board 41 is set to the end bracket. 6 is set to be smaller than the inner diameter of the cylindrical portion 27.
Further, the first rigid board 41 is formed with notches 38 at equal intervals in the circumferential direction, thereby preventing interference between the first rigid board 41 and the bolts 18 for fixing the brackets 5 and 6. It can be avoided.

  On the other hand, the second rigid substrate 42 is located in each axial end of the rotary shaft 13 and outside the end bracket 6 in the axial direction, and further inward in the axial direction than the sensor magnet 28 provided at one end of the rotary shaft 13. Is arranged. The second rigid board 42 is fixed to the end bracket 6 via stud bolts 39. The diameter of the hole 40 formed in the annular portion 42a of the second rigid substrate 42 is also set to a size that allows the rotation shaft 13 to be inserted.

  The flexible substrate 43 is routed between the first rigid substrate 41 and the annular portion 42 a of the second rigid substrate 42. In other words, the first rigid substrate 41 and the second rigid substrate 42 are arranged to face each other with the end bracket 6 sandwiched by curving the flexible substrate 43.

Here, as shown in FIGS. 3, 4, 7, and 8, a motor driving unit that supplies current to each winding 11 wound around the tooth portion 10 of the stator 3 is provided on the first rigid board 41. 44 is implemented.
The motor drive unit 44 includes a plurality of pre-drive circuits 46 mounted on the surface of the first rigid board 41, a current sensor 47, a plurality of switching elements 48 mounted on the back surface of the first rigid board 41, and the like. Have.

  The switching element 48 has a configuration in which a transistor such as a field effect transistor (FET) and a diode that prevents reverse flow between the drain and source of the FET (transistor) are connected in parallel to the motor drive power supply E1. (See FIGS. 7 and 8). A bare chip is used as the FET, and the space occupied by the FET is reduced by resin molding the bare chip (see FIG. 4).

  The switching element 48 forms an H-bridge circuit for each phase using four adjacent switching elements 48. That is, as shown in FIG. 7, since the servo motor 1 of this embodiment is supposed to drive a U-phase, V-, and W-phase three-phase motor, a first current is supplied to the U-phase winding 11. A bridge circuit 51, a second bridge circuit 52 that supplies current to the V-phase winding 11, and a third bridge circuit 53 that supplies current to the W-phase winding 11, each using four switching elements 48. Forming.

  More specifically, as shown in FIG. 8, the first bridge circuit 51 connects two switching elements 48 in series with the motor drive power source E1 to form one arm 54. Two motor drive power supplies E1 are connected in parallel. A terminal portion of the U-phase winding 11 is connected to a midpoint between the switching elements 48 of the arms 54 and 54, respectively.

  The switching element 48 of each arm 54 is connected to the pre-drive circuit 46, respectively. The pre-drive circuit 46 controls ON / OFF of each switching element 48. A current in a desired direction flows through the U-phase winding 11 by switching each switching element 48 between ON and OFF by the pre-drive circuit 46.

  The second bridge circuit 52 and the third bridge circuit 53 have the same configuration as the first bridge circuit 51. Each arm 54, 54 of the second bridge circuit 52 is connected to the end of the V-phase winding 11 at the midpoint between the switching elements 48, 48, respectively. Each arm 54, 54 of the third bridge circuit 53 is connected to the end of the W-phase winding 11 at the midpoint between the switching elements 48, 48.

As shown in FIG. 7, a current sensor 47 is provided between the terminal portion of the winding 11 and each bridge circuit 51, 52, 53. The current sensor 47 is for detecting each phase current (winding current). The current sensor 47 outputs a detection signal of each phase current (winding current) to the second rigid board 42.
In addition, the motor drive unit 44 is provided with a temperature sensor 65. The temperature sensor 65 is for detecting the temperature of the first rigid substrate 41.
The first rigid board 41 configured in this manner is arranged with the switching element 48 facing the stator 3 (see FIG. 2).

A power supply circuit unit 45 that supplies a desired current to the motor drive unit 44 is mounted on the second rigid board 42. For this reason, the first rigid substrate 41 and the second rigid substrate 42 are connected to each other by the flexible substrate 43, and also supply power from the motor drive power supply E1 from the power supply circuit unit 45 to the motor drive unit 44. Lead wires 71 are connected (see FIGS. 1 and 2). A pin header may be provided in place of the lead wire 71.
The power supply circuit unit 45 includes a motor drive power supply connector 56, a control circuit power supply connector 57, an aluminum electrolytic capacitor 58 for smoothing the power supply, an insulating interface circuit 59, an internal power supply circuit 60, and the like mounted on the surface of the second rigid board 42. The communication circuit 61, the Hall element 29, the rotation angle detection circuit 63, the overcurrent detection circuit 64, and the like mounted on the back surface of the second rigid board 42 are provided.

  Further, the motor drive power supply E1 is connected to the power supply circuit section 45 through a motor drive power supply connector 56, and a control circuit power supply E2 for driving each circuit is connected through a control circuit power supply connector 57. Further, in addition to the power sources E1 and E2, an ECU circuit board 55 for controlling the drive of the servo motor 1 is connected.

  The aluminum electrolytic capacitor 58 is a circuit for smoothing the pulsating current contained in the rectified current to a state closer to direct current. Aluminum electrolytic capacitor 58 is connected to motor drive power connector 56. That is, the motor drive power supply E1 supplies a smoothed current to each bridge circuit 51, 52, 53 of the motor drive unit 44 via the motor drive power supply connector 56 and the aluminum electrolytic capacitor 58.

  The internal power supply circuit 60 is a circuit for driving each circuit constituting the drive device 7 and is connected to the control circuit power supply connector 57. In other words, the control circuit power supply E2 supplies power to each circuit via the control circuit power supply connector 57 and the internal power supply circuit 60.

  The hall element 29 constitutes the other of the encoder 30 for detecting the rotation angle of the rotary shaft 13. The hall element 29 is a portion corresponding to the sensor magnet 28 and is provided in the annular portion 42a of the second rigid substrate 42 with a 90 ° interval in the circumferential direction around the rotation shaft 13 (FIG. 4). reference). That is, the servo motor 1 of this embodiment does not need to separately provide an encoder for detecting the rotation angle of the rotary shaft 13, and is in a state where the encoder 30 is incorporated in the drive device 7.

The Hall element 29 detects information indicating a change in the magnetic field generated from the sensor magnet 28, and outputs a sine wave analog signal with a 90 ° phase shift to the rotation angle detection circuit 63. The rotation angle detection circuit 63 detects the rotation angle of the rotary shaft 13 based on the output signal from the hall element 29 and outputs it to the communication circuit 61.
In addition, the power supply circuit unit 45 includes an A / D converter circuit 66, and a detection signal of each phase current (winding current) output from a current sensor 47 provided in the motor drive unit 44 is an A / D converter. The data is output to the communication circuit 61 via the circuit 66.

  The communication circuit 61 performs signal communication by converting into a differential signal conforming to the LVDS (Low Voltage Differential Signaling) method. The communication circuit 61 outputs an output signal from the rotation angle detection circuit 63, an output signal from the temperature sensor 65, And a detection signal of each phase current (winding current) output from the current sensor 47 via the A / D converter circuit 66 to the ECU circuit board 55 and based on a control signal output from the ECU circuit board 55. Then, a PWM (pulse width modulation) signal is output to the pre-drive circuit 46 via the insulation interface circuit 59.

The ECU circuit board 55 is a control device provided outside the drive device 7. The ECU circuit board 55 is connected to the communication circuit 67, which converts the differential signal in accordance with the LVDS method to perform signal communication, and the communication circuit 67. And a servo control circuit 68. Further, the servo control circuit 68 is connected to the host control device via the communication circuit 69.
The servo control circuit 68 outputs an output signal from the rotation angle detection circuit 63, an output signal from the temperature sensor 65, and each phase current (winding current) output from the current sensor 47 via the A / D converter circuit 66. Based on the detection signal, an appropriate PWM (pulse width modulation) signal is output to the pre-drive circuit 46 via the communication circuits 67 and 61 and the insulation interface circuit 59.

The insulation interface circuit 59 cuts the edge of the signal voltage system between the interfaces (between the communication circuit 61 and the insulation interface circuit 59).
In addition to the signal from the communication circuit 61, the output signal from the overcurrent detection circuit 64 is input to the insulation interface circuit 59. The overcurrent detection circuit 64 has a resistor R provided in the motor drive power supply line, and outputs a current value detected here to the insulation interface circuit 59. The insulation interface circuit 59 also functions as a fail-safe circuit that stops the output of the PWM signal to the pre-drive circuit 46 when the current value detected by the overcurrent detection circuit 64 exceeds a preset threshold value. is doing.

The pre-drive circuit 46 controls ON / OFF of each switching element 48 based on the output signal from the insulation interface circuit 59.
The second rigid board 42 configured in this way is disposed so that the surface faces the first rigid board 41 side (see FIGS. 1, 3, and 6).

  Here, an opening 70 is formed in the end bracket 6 at a portion corresponding to the aluminum electrolytic capacitor 58 mounted on the second rigid substrate 42. By forming the opening 70, interference between the aluminum electrolytic capacitor 58 and the end bracket 6 can be avoided, and the second rigid board 42 can be further disposed on the end bracket 6 side.

Next, the operation of this embodiment will be described.
Power is supplied to the power supply circuit unit 45 from the motor drive power supply E1 and the control circuit power supply E2. In the power supply circuit unit 45, the power of the control circuit power supply E2 is supplied to each circuit through the internal power supply circuit 60. On the other hand, the motor drive power supply E 1 is supplied to the motor drive unit 44 via the aluminum electrolytic capacitor 58.

When current is supplied to each bridge circuit 51, 52, 53 of the motor drive unit 44 and the rotary shaft 13 of the servo motor 1 is rotated, the current flowing through the windings 11 of the U phase, V phase, and W phase is supplied to the motor drive unit. It is detected by 44 current sensors 47. The current values of the phases U, V, and W are input to the A / D converter circuit 66 as analog signals. The A / D converter circuit 66 converts the analog signal into a pulsed digital signal and serially outputs it to the communication circuit 61.
Simultaneously with the current detection of the current sensor 47, a rotation angle detection signal is output from the hall element 29 of the power supply circuit unit 45 to the communication circuit 61 via the rotation angle detection circuit 63. Further, a temperature detection signal of the first rigid board 41 by the temperature sensor 65 is also output to the communication circuit.

  Each output signal is output from the communication circuit 11 to the ECU circuit board 55. In the ECU circuit board 55, the signal input to the communication circuit 67 is output to the servo control circuit 68. The servo control circuit 68 determines the energization switching timing and energization phase for the winding 11 based on each output signal. As a result, PWM signals corresponding to the phases U, V, and W are output. These PWM signals are output to the motor drive unit 44 via the communication circuits 67 and 61 and the insulation interface circuit 59.

  In the motor drive unit 44, each PWM signal is input from the insulation interface circuit 59 to the pre-drive circuit 46, and ON / OFF control of the switching elements 48 of the bridge circuits 51, 52, 53 is performed. A current from the motor drive power source E1 flows through the winding 11 of the servo motor 1 connected to the path where the switching element 48 is turned on. As a result, current flows through the predetermined phases U, V, and W of the corresponding servo motor 1 to rotate the rotating shaft 13.

  Therefore, according to the above-described embodiment, the first rigid board 41 on which the motor driving unit 44 is mounted and the second rigid board 42 on which the power supply circuit unit 45 is mounted are arranged in each shaft end of the rotary shaft 13. Thus, it can be arranged so as to surround the rotation shaft 13. For this reason, even if it is a case where the drive device 7 is arrange | positioned at the housing 2 one end side of the servomotor 1 conventionally, a motor shaft length can be shortened.

  Further, since the Hall element 62 for detecting the rotation angle of the rotation shaft 13 and the rotation angle detection circuit 63 are mounted on the second rigid board 42, a separate rotation angle detection device (encoder) as in the prior art is provided. Therefore, the encoder 30 and the drive device 7 can be integrated (see FIG. 2). For this reason, the space occupied by the encoder 30 can be reduced. Therefore, it is possible to reduce the size and weight of the entire servo motor 1.

It is a disassembled perspective view of the servomotor in embodiment of this invention. It is a longitudinal cross-sectional view of the servomotor in embodiment of this invention. It is a top view which shows the surface of the drive device in embodiment of this invention. It is a top view which shows the back surface of the drive device in embodiment of this invention. It is a perspective view of the servomotor in the embodiment of the present invention. It is a perspective view of the servomotor in the embodiment of the present invention. It is a block diagram of the drive device in the embodiment of the present invention. It is a circuit diagram of the H bridge circuit in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Servo motor 2 Housing 3 Stator 4 Rotor 5 Front bracket 6 End bracket 7 Drive device (motor drive device)
13 Rotating shaft (motor shaft)
28 Sensor magnet 29 Hall element 30 Encoder (rotation angle detector)
41 First rigid substrate 42 Second rigid substrate 42a Ring portion 42b Rectangular portion 43 Flexible substrate 44 Motor drive portion 45 Power supply circuit portion 48 Switching element 51 First bridge circuit (bridge circuit)
52 Second bridge circuit (bridge circuit)
53 Third bridge circuit (bridge circuit)
54 Arm 55 ECU circuit board (external control device)
E1 Motor drive power supply E2 Control circuit power supply

Claims (3)

A motor drive unit having a bridge circuit for switching energization to the coils of each phase;
An external power supply is connected and a power supply circuit section for supplying current to the motor drive section,
The power supply circuit unit is a motor drive device configured to supply a predetermined current to the motor drive unit at a predetermined energization switching timing based on a control signal of an external control device,
The motor drive unit is mounted on an annular first rigid substrate that can be inserted through a motor shaft, and the power supply circuit unit is mounted on an annular second rigid substrate that can be inserted through the motor shaft.
A motor driving device characterized in that the first rigid substrate and the second rigid substrate are connected via a flexible substrate. A rotation angle detection device for detecting a rotation angle of the motor shaft is provided in the power supply circuit unit,
The motor drive device according to claim 1, wherein the external control device determines an energization switching timing based on a detection result of the rotation angle detection device. The motor drive device according to claim 1 or 2 is provided on one end side of the motor housing,
A servo motor, wherein the flexible substrate is curved and the first rigid substrate and the second rigid substrate are arranged to face each other.

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