JP2012010465A - Motor controller and vehicular steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller capable of achieving easy layout and stable motor driving.SOLUTION: A power substrate 49 mounted with a field effect transistor as a motor driving element and a control substrate 50 that controls the motor driving element are disposed to face each other at a predetermined interval. A bonding wire 711 corresponding to a part of a current route 71 of the power substrate 49 is connected with a pad 91 for bonding wire connection on the power substrate 49 and a bus bar 81. The control substrate 50 is provided with a contactless type current sensor 66 that faces the bonding wire 711 corresponding to the part of the current route 71 of the power substrate 49.

Description

  The present invention relates to a motor control device and a vehicle steering device.

  A current flowing through a winding terminal connected to an armature winding of an electric motor, comprising: a power board equipped with a semiconductor switching element for supplying electric power to the electric motor; and a control board equipped with a control circuit for controlling the switching element. Has been proposed (for example, the 39th to 43rd paragraphs of Patent Document 1 and the drawings in the drawings). 11 to FIG. 13).

Japanese Patent Laid-Open No. 2002-120739

In Patent Document 1, the winding terminal connected to the armature winding of the motor needs to face the current detection unit on the control board. For this purpose, the winding terminal is bent or extended. In some cases, it is necessary to change the layout of the winding terminals.
The present invention has been made under such a background, and an object of the present invention is to provide a motor control device and a vehicle steering device that are easy to lay out and can perform stable motor driving.

  To achieve the above object, the present invention provides a power board (49) on which motor drive elements (UH, UL; VH, VL; WH, WL) are mounted, and a control board (50) for controlling the motor drive elements. The power board and the control board are arranged so as to face each other with a predetermined distance therebetween, and a part (711, 71) of a current path (71, 72, 73) of the power board is disposed on the control board. 731; 740, 750) is provided with a motor control device (12) provided with a non-contact type current detector (66, 67; 66A, 67A).

  In the present invention, since the non-contact type current detector is provided on the control board, the temperature rise of the power board can be suppressed, so that stable motor driving can be performed. That is, if a detection unit using a resistor is arranged on the power board, the temperature of the power board is likely to rise, but this is not the case with the present invention. Further, the non-contact type current detection unit of the control board may be opposed to a part of the current path of the power board. For example, it may be arranged to face any of a large number of bonding wires, and the degree of freedom of layout of the current detection unit of the control board can be increased. In addition, the power board can be reduced in size as compared with the case where the resistor is arranged on the power board.

Here, in the present invention, the current path of the power board is a current path mounted on the power board. For example, a bonding wire whose one end is connected to a bonding wire connecting pad on the power board is also a power board. Are included in the current path.
In addition, the current path of the power board is a current path (71, 82, 83) connected to the bus bar (81, 82, 83) connected to the field coil (18U, 18V, 18W) of the electric motor and the motor driving element. 72, 73) (claim 2). In this case, the occurrence of abnormality in the motor drive element can be easily detected.

  The part of the current path may be a bonding wire (711, 731; 740, 750) connected to a bonding wire connection pad (91, 93; 94, 95) on the power substrate. (Claim 3). Since many bonding wires of this type exist on the control board, the degree of freedom in the layout of the current detection unit on the control board can be increased.

The present invention also provides a vehicle steering device (1) comprising the motor control device and an electric motor (18) driven by the motor control device to apply a steering force to a steering mechanism (claim). 4). In this case, it is possible to realize an electric power steering device that can perform a small and stable motor drive.
In addition, in the above, the numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

It is a mimetic diagram showing a schematic structure of an electric power steering device concerning one embodiment of the present invention. It is a schematic perspective view of a steering assist mechanism. It is sectional drawing of the principal part of an electric power steering device. It is a schematic circuit diagram of the principal part of a motor control apparatus. It is a schematic side view of the principal part of a motor control apparatus. It is a schematic circuit diagram of the principal part of the motor control apparatus of another embodiment of this invention. It is a schematic side view of the principal part of the motor control apparatus of embodiment of FIG.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of an electric power steering apparatus 1 as a vehicle steering apparatus according to an embodiment of the present invention.
Referring to FIG. 1, an electric power steering device 1 assists steering by a steering wheel 2 as a steering member, a steering mechanism 4 that steers the steered wheels 3 in conjunction with rotation of the steering wheel 2, and a driver. A steering assist mechanism 5 is provided. The steering wheel 2 and the steering mechanism 4 are mechanically connected via a steering shaft 6 and an intermediate shaft 7.

In the present embodiment, a description will be given according to an example in which the steering assist mechanism 5 applies assist force (steering assist force) to the steering shaft 6. However, the present invention can also be applied to a structure in which the steering assist mechanism 5 applies an assist force to a pinion shaft described later, or a structure in which the steering assist mechanism 5 applies an assist force to a rack shaft described later.
The steering shaft 6 includes an input shaft 8 connected to the steering wheel 2 and an output shaft 9 connected to the intermediate shaft 7. The input shaft 8 and the output shaft 9 are connected via a torsion bar 10 so as to be relatively rotatable on the same axis.

  A torque sensor 11 disposed around the steering shaft 6 detects the steering torque input to the steering wheel 2 based on the relative rotational displacement amounts of the input shaft 8 and the output shaft 9. The torque detection result of the torque sensor 11 is input to an ECU (Electronic Control Unit) 12 as a motor control device for assisting steering. Further, the vehicle speed detection result from the vehicle speed sensor 90 is input to the ECU 12. The intermediate shaft 7 connects the steering shaft 6 and the steering mechanism 4.

The steering mechanism 4 includes a rack and pinion mechanism including a pinion shaft 13 and a rack shaft 14 as a steered shaft. A steered wheel 3 is connected to each end of the rack shaft 14 via a tie rod 15 and a knuckle arm (not shown).
The pinion shaft 13 is connected to the intermediate shaft 7. The pinion shaft 13 rotates in conjunction with the steering of the steering wheel 2. A pinion 16 is provided at the tip (lower end in FIG. 1) of the pinion shaft 13.

  The rack shaft 14 extends linearly along the left-right direction of the automobile. A rack 17 that meshes with the pinion 16 is formed in the middle of the rack shaft 14 in the axial direction. By the pinion 16 and the rack 17, the rotation of the pinion shaft 13 is converted into the axial movement of the rack shaft 14. The steered wheel 3 can be steered by moving the rack shaft 14 in the axial direction.

When the steering wheel 2 is steered (rotated), this rotation is transmitted to the pinion shaft 13 via the steering shaft 6 and the intermediate shaft 7. The rotation of the pinion shaft 13 is converted into an axial movement of the rack shaft 14 by the pinion 16 and the rack 17. Thereby, the steered wheel 3 is steered.
The steering assist mechanism 5 includes a steering assist electric motor 18 and a speed reduction mechanism 19 as a transmission mechanism for transmitting the output torque of the electric motor 18 to the steering mechanism 4. The speed reduction mechanism 19 includes a worm shaft 20 as a drive gear and a worm wheel 21 as a driven gear that meshes with the worm shaft 20. The speed reduction mechanism 19 is accommodated in the gear housing 22.

The worm shaft 20 is connected to a rotating shaft (not shown) of the electric motor 18 through a joint (not shown). The worm shaft 20 is rotationally driven by the electric motor 18. Further, the worm wheel 21 is connected to the steering shaft 6 so as to be integrally rotatable.
When the electric motor 18 rotationally drives the worm shaft 20, the worm wheel 21 is rotationally driven by the worm shaft 20, and the worm wheel 21 and the steering shaft 6 rotate integrally. The rotation of the steering shaft 6 is transmitted to the pinion shaft 13 via the intermediate shaft 7. The rotation of the pinion shaft 13 is converted into the axial movement of the rack shaft 14. Thereby, the steered wheel 3 is steered. That is, the steered wheels 3 are steered by rotating the worm shaft 20 by the electric motor 18.

  The electric motor 18 is a three-phase brushless motor, and is controlled by the ECU 12 as a motor control device. The ECU 12 controls the electric motor 18 based on the torque detection result from the torque sensor 11, the vehicle speed detection result from the vehicle speed sensor 90, and the like. Specifically, the ECU 12 determines a target assist amount using a map in which the relationship between the torque and the target assist amount is stored for each vehicle speed, and controls the assist force generated by the electric motor 18 to approach the target assist amount. To do.

FIG. 2 is a schematic perspective view of the steering assist mechanism 5. Referring to FIG. 2, a housing H for housing ECU 12 as a control device is configured by a first housing 23 and a second housing 24 that are in contact with each other.
The first housing 23 and the second housing 24 are each formed in a substantially square box shape with one end opened. The ends of the first and second housings 23 and 24 are abutted and fastened to each other by a fixing screw 25.

On the other hand, the motor housing 26 of the electric motor includes a cylindrical motor housing main body 27 and the first housing 23 described above.
The gear housing 22 includes a cylindrical drive gear housing 28 that houses the worm shaft 20, a tubular driven gear housing 29 that houses the worm wheel 21, and the second housing 24. Has been.

FIG. 3 is a cross-sectional view of the main part of the electric power steering apparatus 1. Referring to FIG. 3, the first housing 23 and the second housing 24 form a storage chamber 32 that stores the ECU 12.
The first housing 23 includes a first inner wall surface 33 that defines a part of the accommodation chamber 32, and the second housing 24 includes a second inner wall surface 34 that defines a part of the accommodation chamber 32, and these first inner wall surfaces 33 and the second inner wall surface 34 face the axial direction X1 of the rotating shaft 35 of the electric motor 18.

  The rotating shaft 35 and the worm shaft 20 of the electric motor 18 are arranged coaxially side by side, and both are coaxially connected via a joint 36 so that power can be transmitted. The worm shaft 20 is supported at both ends by the drive gear housing 28 via the first bearing 37 and the second bearing 38. The rotary shaft 35 is rotatably supported by a third bearing 46 held by the first housing 23 and a fourth bearing 47 held by the motor housing body 27.

In the present embodiment, a three-phase brushless motor is used as the electric motor 18. The electric motor 18 includes the motor housing 26, and a rotor 39 and a stator 40 accommodated in the motor housing 26. The rotor 39 is connected to the rotary shaft 35 so as to be integrally rotatable.
The stator 40 is fixed to the inner periphery of the motor housing body 27 of the motor housing 26. The stator 40 includes a stator core 41 fixed to the inner periphery of the motor housing body 27, and a plurality of field coils 18U, 18V, 18W. Stator core 41 includes an annular yoke of stator core 41 and a plurality of teeth protruding radially inward from the inner periphery of this yoke. Each field coil 18U, 18V, 18W is wound around the corresponding tooth.

  Further, in the motor chamber 43 defined by the motor housing main body 27 and the first housing 23 of the motor housing 26, bus bars 81, 82, 83 having an annular shape or a C shape are accommodated. Each phase field coil 18U, 18V, 18W wound around each tooth is connected to corresponding bus bar 81, 82, 83, respectively. Each bus bar 81, 82, 83 is a conductive connecting material used for a connection portion between the corresponding field coil 18U, 18V, 18W and a power board 49 described later. Each bus bar 81, 82, 83 functions as a power distribution member for distributing power from the power board 49 to the corresponding field coils 18U, 18V, 18W.

The first housing 23 includes a partition wall 59 that partitions the accommodation chamber 32 and the motor chamber 43 as a bottom wall. The partition wall 59 is provided with the first inner wall surface 33.
Further, a cylindrical portion 48 extending from the partition wall 59 toward the second housing 24 side is formed. An outer ring of the third bearing 46 is held on the inner periphery of the cylindrical portion 48.
In the accommodation chamber 32, a power board 49 and a control board 50 as a multilayer circuit board constituting a part of the ECU 12 are accommodated and held. A power board 49 as a circuit board is mounted with at least a part of a power circuit (for example, a field effect transistor) for driving the electric motor 18. Although not shown in detail in FIG. 3, some of the bus bars 81, 82, 83 connected to the field coils 18 U, 18 V, 18 W pass through the partition wall 59 of the first housing 23. It enters the storage chamber 32 and is connected to a bonding wire (not shown in FIG. 3) power substrate 49 described later.

  In the accommodation chamber 32, the power board 49 is disposed relatively close to the first inner wall surface 33 among the first inner wall surface 33 and the second inner wall surface 34. The partition wall 59 having the first inner wall surface 33 includes a thick portion 59a and a relatively thin portion 59b that are relatively thick in the axial direction X1 of the rotating shaft 35 of the electric motor 18. The thick portion 59a is provided so as to protrude into the accommodation chamber 32. The power board 49 is arranged in contact with the first inner wall surface 33 in the thick part 59a. The thick part 59 a is a seat part that receives the power board 49.

In the present embodiment, the power board 49 is in contact with the first inner wall surface 33 in the thick part 59a so as to be able to conduct heat, and the thick part 59a is for releasing the heat of the power board 49. It functions as a heat sink.
The control board 50 is disposed between the second inner wall surface 34 of the second housing 24 and the power board 49 with respect to the axial direction X1 of the rotating shaft 35 of the electric motor 18. The power board 49 and the control board 50 are arranged at a predetermined interval with respect to the axial direction X1 of the rotating shaft 35 of the electric motor 18.

Next, FIG. 4 is a schematic diagram of a main part of the ECU 12 as a motor control device. The electric motor 18 includes a stator having a U-phase field coil 18U, a V-phase field coil 18V, and a W-phase field coil 18W, and a permanent magnet that receives a repulsive magnetic field from these field coils 18U, 18V, and 18W. And a rotor that has been made.
The power circuit 52 is a three-phase bridge inverter circuit, and includes a series circuit 53 of field effect transistors UH and UL as a pair of motor driving elements corresponding to the U phase of the electric motor 18 and a pair of motors corresponding to the V phase. A series circuit 54 of field effect transistors VH and VL as a driving element, and a series circuit 55 of field effect transistors WH and WL as a pair of motor driving elements corresponding to the W phase, a DC power supply 56 and a ground 57 Are connected in parallel.

The U-phase field coil 18U of the electric motor 18 is connected to a connection point 53a between the field effect transistors UH and UL, and the V-phase field coil 18V is connected to a connection point 54a between the field effect transistors VH and VL. The W-phase field coil 18W is connected to a connection point 55a between the series circuits WH and WL of the field effect transistor.
A shunt resistor 62 for detecting current consumption of the electric motor 18 is disposed in a DC circuit 61 that connects the ground 57 and the three-phase bridge inverter circuit. The shunt resistor 62 detects current consumption of the electric motor 19 during normal control.

  Also, three series circuits 63, 64, which connect the field effect coils U, 18V, 18W of the corresponding phase field effect transistors UH, UL; VH, VL; Current sensors 66 and 67 as non-contact type current detection units for detecting the current of the corresponding phases are arranged opposite to any two series circuits of 65, for example, DC circuits 63 and 65, respectively. Yes.

  Specifically, each of the series circuits 63, 64, 65 includes bus bars 81, 82, 83 connected to the current paths 71, 72, 73 of the power board 49 and the field coils 18U, 18V, 18W of the respective phases. Including. The current paths 71, 72, 73 of the power board 49 include bonding wires 711, 721, 731 connected to bonding wire connection pads 91, 92, 93 on the power board 49.

In the present invention, the current path of the power board 49 is a current path mounted on the power board 49. For example, one end is connected to bonding wire connection pads 91, 92, 93 on the power board 49. Bonding wires 711 and 731 are also included in the current path of the power board 49.
As shown in FIG. 4, non-contact type current sensors 66 and 67 are arranged so as to face bonding wires 711 and 721 as a part of current paths 71 and 72 of the power substrate 49, respectively. Output signals of the current sensors 66 and 67 are mounted on the control board 50 and input to a control circuit 68 that controls driving of the field effect transistors UH, UL; VH, VL; WH, WL as motor driving elements. It has become.

  As shown in FIG. 5, one end 711 a of the bonding wire 711 is connected to the bonding wire connecting pad 91 on the power substrate 49, and the other end 711 b of the bonding wire 711 is connected to the corresponding bus bar 81. Although not shown, the bonding wires 721 and 731 similarly connect the bonding wire connection pads 92 and 93 on the power substrate 49 to the corresponding bus bars 82 and 83.

As the non-contact type current sensors 66 and 67, for example, a known configuration using a Hall element can be used. Moreover, you may make it use a toroidal coil as a non-contact-type electric current sensor.
According to the present embodiment, the power board 49 and the control board 50 are arranged so as to face each other with a predetermined distance therebetween, and the non-contact type current sensors 66 and 67 are provided on the control board 50. , 67 are opposed to bonding wires 711, 731 corresponding to part of the current paths 71, 73 of the power substrate 49.

  If a detection unit using a resistor is arranged on the power board, the power board easily rises in temperature, and a wiring for connecting the detection unit made of the resistor and the control board is necessary, and the power board is large. There is a problem of becoming. On the other hand, in the present embodiment, since the non-contact type current detection units 66 and 67 are provided on the control board 50, the temperature rise of the power board 49 can be suppressed to stabilize the operation of the power board 49. In addition, the above wiring can be omitted, and the power board 49 can be downsized. As a result, it is possible to provide the electric power steering apparatus 1 that is small and can perform motor driving with stable operation.

Further, the non-contact type current sensors 66 and 67 on the control board 50 may be opposed to a part of the current paths 71 and 73 of the power board 49. For example, it may be made to face any of a large number of bonding wires, and the degree of freedom of layout of the current sensors 66 and 67 on the control board 49 can be increased.
The current paths 71, 72, 73 of the power board 49 include bus bars 81, 82, 83 connected to the field coils 18U, 18V, 18W of the electric motor 18, and electrolytic effect transistors UH, UL as motor driving elements. VH, VL; WH, WL, and non-contact current sensors 66, 67 are opposed to two current paths (current paths 71, 73 in this embodiment). As a result, control can be continued even when an abnormality occurs in the shunt resistor 62.

In addition, a part of the current paths 71 and 73 that are current detection targets are bonding wires 711 and 713 that are connected to bonding wire connection pads 91 and 93 on the power substrate 49. Since there are many power boards 49, the control board 50 can increase the degree of freedom in layout of the current sensors 66 and 67.
Specifically, as shown in FIGS. 6 and 7, non-contact current sensors 66A and 67A may be opposed to bonding wires 740 and 750 on the power substrate 49, respectively. In this example, bonding wires 740 and 750 have one end connected to bonding wire connection pads 94 and 95 on the power substrate 49 and the other end connected to a field effect transistor (for example, UH or WH).

  The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims. For example, in the above-described embodiment, an example in which the present invention is applied to a so-called column assist type electric power steering apparatus has been described. The present invention may be applied to the electric power steering apparatus.

  In the above-described embodiment, the example in which the present invention is applied to the electric power steering apparatus that outputs the output of the electric motor as the steering assist force has been described, but the present invention is not limited thereto. For example, a transmission ratio variable mechanism that includes a transmission ratio variable mechanism capable of changing a ratio of a steered wheel turning angle to a steering angle of a steering member, and that uses an output of an electric motor to drive the transmission ratio variable mechanism, is used for vehicle steering. Even if the present invention is applied to a device, a steer-by-wire type vehicle steering device in which the mechanical connection between the steering member and the steered wheel is released and the steered wheel is steered by the output of the electric motor, etc. Good.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (vehicle steering device), 2 ... Steering member, 4 ... Steering mechanism, 12 ... ECU (motor control device), 18 ... Electric motor, 49 ... Power board, 50 ... Control board, 52 ... Power Circuit 56 ... DC power source 57 ... Grounding 66, 67; 66A, 67A ... Current sensor (non-contact type current detection unit) 68 ... Control circuit 71, 72, 73 ... Current path of power board, 711, 721, 731; 740, 750 ... bonding wires (part of the current path of the power substrate), 81, 82, 83 ... busbar, UH, UL; VH, VL; WH, WL ... field effect transistor (motor drive element )

Claims (4)

A power board on which a motor driving element is mounted;
A control board for controlling the motor drive element,
The power board and the control board are arranged so as to face each other with a predetermined distance therebetween,
A motor control device, wherein the control board is provided with a non-contact type current detection unit facing a part of the current path of the power board.   The motor control device according to claim 1, wherein the current path of the power board is a current path that connects the bus bar connected to the field coil of the electric motor and the motor driving element.   3. The motor control device according to claim 1, wherein the part of the current path is a bonding wire connected to a bonding wire connecting pad on the power substrate.   A vehicle steering apparatus comprising: the motor control apparatus according to any one of claims 1 to 3; and an electric motor that is driven by the motor control apparatus and applies a steering force to a steering mechanism.

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