JP2016061713A - Rotation angle sensor, brushless motor including the same, and electric power steering device and vehicle mounting rotation angle sensor thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle sensor which does not require an additional installation of a mechanism for electrically connecting a sensor to a control unit, allows reduction in dimensions and costs, does not generate magnetic interferences between the sensors even when a multiple system is configured, and which can accurately detect an angle, and to provide an electric power steering device and a vehicle in which the rotation angle sensor is mounted.SOLUTION: A control unit 120 including a control board 121 is disposed at a one end side of a rotation axis 101, a magnet part 102 is fixed to the one end of the rotation axis 101, and a magnetic detection element 122 is arranged in a position of the control board 121 opposite the magnet part 102, and detects a rotation angle of the rotation axis 101.SELECTED DRAWING: Figure 4

Description

The present invention is a configuration in which a control unit having a control board is mounted on the side opposite to the output side of the rotor rotation shaft of the brushless motor, and a magnet portion is fixed to the shaft end of the rotor rotation shaft of the brushless motor. The present invention relates to a rotation angle sensor that magnetically detects a rotation angle by a magnetic detection element installed on a control board, a brushless motor equipped with the rotation angle sensor, an electric power steering apparatus equipped with the same, and a vehicle.

An electric power steering device mounted on a vehicle applies an assist force by a motor (for example, a brushless three-phase motor) to a steering system of the vehicle based on a current command value calculated based on at least a steering torque. It is driven and controlled by an inverter consisting of

  There is an electric power steering device (EPS) as a device equipped with a motor control device for controlling a motor. The electric power steering device applies a steering assist force (assist force) to the steering mechanism of a vehicle by the rotational force of the motor. Yes, the driving force of the motor controlled by the electric power supplied from the inverter is applied to the steering shaft or the rack shaft by a transmission mechanism such as a gear.

  Such a conventional electric power steering apparatus performs feedback control of the motor current in order to accurately generate the torque of the steering assist force. In feedback control, the motor applied voltage is adjusted so that the difference between the steering assist command value (current command value) and the motor current detection value is small. The adjustment of the motor applied voltage is generally performed by PWM (pulse width). Modulation) control duty is adjusted, and a brushless motor having excellent maintainability is generally used as the motor.

  The general configuration of the electric power steering apparatus will be described with reference to FIG. The tie rods 6a and 6b are connected to the steered wheels 8L and 8R via the hub units 7a and 7b. Further, the column shaft 2 is provided with a torque sensor 10 for detecting the steering torque of the handle 1 and a steering angle sensor 14 for detecting the steering angle θ, and the motor 20 for assisting the steering force of the handle 1 is provided with the reduction gear 3. Are connected to the column shaft 2 via The control unit (ECU) 30 that controls the electric power steering apparatus is supplied with electric power from the battery 13 and also receives an ignition key signal via the ignition key 11. The control unit 30 calculates a current command value of an assist (steering assist) command based on the steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the EPS motor 20 is controlled by the voltage control command value Vref subjected to.

  The steering angle sensor 14 is not essential and may not be provided, and the steering angle can be acquired from a rotational position sensor such as a resolver connected to the motor 20.

  The control unit 30 is connected to a CAN (Controller Area Network) 40 that transmits and receives various types of vehicle information, and the vehicle speed Vs can also be received from the CAN 40. In addition, the control unit 30 can be connected to a non-CAN 41 that exchanges communication, analog / digital signals, radio waves, and the like other than the CAN 40, and has a control board on which electronic components and the like are mounted.

  The control unit 30 is mainly composed of a CPU (including MCU, MPU, etc.). FIG. 2 shows general functions executed by a program inside the CPU.

  The function and operation of the control unit 30 will be described with reference to FIG. 2. The steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12 (or from the CAN 50) are expressed as a current command value Iref1. The current command value calculation unit 31 to be calculated is input. The current command value calculation unit 31 calculates a current command value Iref1, which is a control target value of the current supplied to the motor 20, using an assist map or the like based on the input steering torque Ts and vehicle speed Vs. The current command value Iref1 is input to the current limiter 33 through the adder 32A, and the current command value Irefm whose maximum current is limited is input to the subtractor 32B, and the deviation I (Irefm) from the fed back motor current value Im. -Im) is calculated, and the deviation I is input to the PI control unit 35 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics are improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is PWM driven via an inverter 37 as a drive unit. The current value Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction unit 32B. The inverter 37 uses a FET as a drive element, and is configured by a bridge circuit of the FET.

  A compensation signal CM from the compensation signal generator 34 is added to the adder 32A, and the compensation of the steering system system is performed by adding the compensation signal CM to improve the convergence and inertia characteristics. . The compensation signal generator 34 adds the self-aligning torque (SAT) 34-3 and the inertia 34-2 by the adder 34-4, and further adds the convergence 34-1 to the addition result by the adder 34-5. The addition result of the adder 34-5 is used as the compensation signal CM.

  As a motor used in such an electric power steering apparatus, a brushless motor is usually adopted because of demands for higher output, smaller size, and lower noise. The brushless motor requires a magnetic pole position detection sensor of the rotor. When a resolver is used as the magnetic pole position detection sensor of the rotor, it is necessary to adjust the position of the resolver in the rotational direction of the stator with respect to the rotor. .

  For this reason, in consideration of assembly, a resolver is arranged outside the motor case on the output side, and the position of the resolver stator can be adjusted from the outside (for example, Japanese Patent No. 3881351 (Patent Document 1)). In addition, a structure in which a resolver is housed in a motor case and a resolver stator in the motor case is rotated from the outside (for example, Japanese Patent Laid-Open No. 2006-320189 (Patent Document 2)) has been proposed.

  However, when the resolver is provided on the output side from which the rotor rotation shaft protrudes, for example, the flange on the output side of the motor case becomes larger, the shape becomes complicated, and the number of parts increases. Further, in the case of a structure in which the resolver is housed inside the motor case, the resolver stator inside the motor case has to be rotated from the outside, resulting in a complicated structure and an increased number of parts. For this reason, in any case, cost increase, assembling property, and deterioration in mounting property are inevitable. In addition, in the latter case in which the resolver is disposed inside, problems such as the resolver being easily affected by heat from the motor coil occur.

  Japanese Unexamined Patent Publication No. 2009-177968 (Patent Document 3) discloses a brushless motor (angle sensor) that solves this problem. That is, the brushless motor (angle sensor) of Patent Document 3 has a structure in which a rotor rotating shaft 101 of a rotor is accommodated in a brushless motor main body 100 via a bearing as shown in FIG. Is also housed. The front side of the motor case is an output side that outputs the rotational force of the rotor by the rotating shaft 101. The rotating shaft 101 passes through the wall portion on the back side of the motor case, and the rotating shaft 101 is connected to the motor case. A resolver 110 is coaxially connected to the protruding portion of the rotating shaft 101 as an angle sensor.

  In addition, a control unit (ECU) 120 is disposed on the back side of the brushless motor 100 (outside the resolver 110), and the drive signal and the angle detection signal of the resolver 110 are exchanged via the harness 111 and the connector 112. This is performed with the control board 121.

Japanese Patent No. 3881351 JP 2006-320189 A JP 2009-177968 A

  Thus, in the conventional configuration, a resolver is used as a rotation angle sensor of a brushless motor. Therefore, connecting parts such as a harness and a connector are required to electrically connect the resolver and the control unit. Further, in the conventional configuration, when configuring a multiplex system for function continuation, it is necessary to arrange two resolvers in series, so that there is a problem that the size required for the sensor is doubled and the size is increased. . Furthermore, when a plurality of resolvers are used to form a multiplex system, each resolver generates an alternating magnetic field, so that magnetic interference occurs between the resolvers, resulting in a problem that detection accuracy deteriorates.

  The present invention has been made under the circumstances described above, and the object of the present invention is to eliminate the need for a separate mechanism for electrically connecting the sensor and the control unit, and to reduce the size and cost. A rotation angle sensor capable of accurately detecting an angle without causing magnetic interference between the sensors even when a multiplex system is configured, a brushless motor including the rotation angle sensor, and an electric motor equipped with the rotation angle sensor To provide a power steering device and a vehicle.

  The present invention relates to a rotation angle sensor, and the object of the present invention is to provide a control unit having a control board on one end side of a rotating shaft, a magnet portion fixed to one end of the rotating shaft, and the magnet on the control board. This is achieved by providing a magnetic detection element at a position facing the part and detecting the rotation angle of the rotary shaft by the magnetic detection element.

  The present invention also relates to a brushless motor, and the object of the present invention is to provide a magnet unit fixed to one end of the rotor rotating shaft opposite to the output side, and a control unit having a control board on the back side of the motor body. The magnetic detection element is installed on the control board disposed so as to face the magnet portion, and has a function of detecting the rotation angle of the rotor rotation shaft by the magnetic detection element. Is achieved.

  The object of the present invention is that the magnet part is formed in a disk shape or a structure in which a magnet is disposed on the disk, or the magnet part is disposed in a polygonal shape or a polygonal shape of a multiple of two. This is achieved more effectively by the structure in which the magnetic sensing elements are provided or by providing a plurality of magnetic sensing elements.

  According to the rotation angle sensor of the present invention, the control unit having the control board is disposed on one end side of the rotation shaft, the magnet part is fixed to one end of the rotation shaft, and the magnetic detection is performed at a position facing the magnet part of the control board. An element is installed, and the rotation angle of the rotation shaft is detected by the magnetic detection element. In the brushless motor, the magnet portion is fixed to the shaft end of the rotor rotation shaft, and the magnetic detection element is installed on the control board of the control unit.

  For this reason, according to this invention, it is not necessary to comprise separately the mechanism for electrically connecting a magnet part and the magnetic detection element of a control unit, and a dimension and cost can be suppressed.

It is a lineblock diagram showing an outline of an electric power steering device. It is a block diagram which shows the structural example of the control unit (ECU) of an electric power steering apparatus. It is sectional drawing which shows the structural example of the conventional brushless motor with an angle sensor. It is sectional drawing which shows the structural example of the brushless motor with an angle sensor (1st Embodiment) of this invention. It is a top view which shows the structural example of a magnet part. It is sectional drawing which shows the structural example of the brushless motor with an angle sensor of this invention (2nd Embodiment).

  In the present invention, a control unit having a control board is arranged on one end side of a rotating shaft, and a disc-shaped or polygonal polygon part having a multiple of 2 is fixed to one end of the rotating shaft. 1 and 2 or more magnetic sensing elements such as magnetoresistive effect elements (MR, AMR, GMR, etc.), magneto-impedance elements, etc. A plurality of rotation angle sensors are provided which detect the rotation angle of the rotation shaft as an absolute angle by a magnetic detection element.

  In addition, a brushless motor equipped with a rotation angle sensor having such a structure includes a magnet portion fixed to one end opposite to the output side of the rotor rotation shaft, and a control unit having a control board is mounted on the back side of the motor body. One or two or more magnetic detection elements are installed on a control board arranged to face a magnet portion having N and S poles. A function of detecting the rotation angle of the rotor rotation shaft as an absolute angle is provided.

  By installing a magnetic detection element on the control board of the control unit, there is no need for a separate mechanism for electrically connecting the rotation angle sensor and the control unit, so the size and cost can be reduced compared to the conventional structure, In particular, the brushless motor is suitable for application to an electric power steering apparatus. Further, by installing two or more magnetic detection elements, it is possible to easily configure a multiplex system for continuing functions such as assist control.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 4 shows the first embodiment corresponding to FIG. 3, and a disc-shaped magnet portion 102 is fixed to one end of the brushless motor main body 100 opposite to the output side of the rotor rotation shaft 101. A plan view of the magnet portion 102 is, for example, as shown in FIG. 5A, and the upper half of the disk member is composed of the N pole and the lower half is composed of the S pole. It may be composed of N-pole and S-pole magnets themselves, or may be constructed by arranging (embedding) magnets in a disk. Further, as shown in FIG. 5 (B) or (C), the magnet portion may have a polygonal shape with a multiple of 2. In this case, the upper half of the polygonal shape is N pole and the lower half is S. It may be composed of poles and may be composed of N-pole and S-pole magnets themselves, or may be constructed by arranging (embedding) magnets on a polygonal substrate. In addition, the up-and-down relationship shown in the drawing is an example, and it is only necessary to divide it into other arbitrary directions.

  A control unit 120 having a control board 121 can be mounted on the back side of the brushless motor main body 100, and a magnetoresistive effect element (MR, AMR) is provided on the control board 121 facing the magnet portion 102. , GMR, etc.), a magnetic detection element 122 such as a magnetic impedance element is provided. Since the magnetic detection element 122 can detect the rotation of the magnet unit 102 without contact, wiring between the magnetic detection element 122 and the magnet unit 102 is unnecessary.

  With such a structure, when the brushless motor is driven, the rotor rotation shaft 101 rotates, and the magnet portion 102 fixed to one end of the rotor rotation shaft 101 also rotates in conjunction with it. The rotation of the magnet unit 102 can be detected magnetically by the magnetic detection element 122, and the rotation angle can be detected.

  In the conventional configuration, since a resolver is used as a rotation angle sensor of a brushless motor, connecting parts such as a harness and a connector are required to electrically connect the resolver and the control unit. However, in the present invention, since the magnet portion is installed on the shaft end of the rotation shaft of the brushless motor and the magnetic detection element is installed on the control board of the control unit, the rotation angle sensor and the control unit are electrically connected. Therefore, it is not necessary to separately configure a mechanism for the purpose, and the size and cost can be reduced.

  The rotation angle sensor of the present invention can be detected by an absolute value, and the angle can be detected only by turning on the power of the sensor. Therefore, the angle can be detected even if the rotating shaft 101 does not rotate.

  FIG. 6 shows the second embodiment corresponding to FIG. 4, and in this embodiment, two magnetic detection elements 123A and 123B are installed on the control board in order to constitute a multiplex system. Since the two magnetic detection elements 123A and 123B are installed, even if one of the magnetic detection elements 123A or 123B fails or malfunctions, the angle detection can be continued and the function can be continued.

  In a configuration using a conventional resolver, when a multiplex system is configured for function continuity, it is necessary to arrange two resolvers in series, so that the size required for the sensor is doubled, and each resolver is further reduced. Since an alternating magnetic field is generated at this point, magnetic interference occurs between the resolvers, and the detection accuracy deteriorates. However, in the present invention, by using a plurality of magnetic detection elements, it is possible to configure a multiplex system for function continuity with a simple and simple structure while suppressing the size and cost.

  In addition, since the rotation angle of the magnet part fixed to the rotating shaft is detected by a plurality of magnetic detection elements, magnetic interference between the sensors due to the multiplex system does not occur, so the angle can be detected accurately. Is possible.

1 Handle 2 Column shaft (steering shaft, handle shaft)
10 Torque sensor 12 Vehicle speed sensor 14 Rudder angle sensor 20 Motor 30, 120 Control unit (ECU)
100 Brushless motor body 101 Rotating shaft (output shaft)
102, 102A, 102B Magnet part 110 Resolver 111 Harness 112 Connector 121 Control board 122, 123A, 123B Magnetic detection element

Claims (10)

A control unit having a control board is disposed on one end of the rotating shaft, a magnet portion is fixed to one end of the rotating shaft, a magnetic detection element is installed at a position facing the magnet portion of the control board, and the magnetic A rotation angle sensor configured to detect a rotation angle of the rotation shaft by a detection element. The rotation angle sensor according to claim 1, wherein the magnet portion has a disk shape or a structure in which a magnet is disposed on the disk. The rotation angle sensor according to claim 1, wherein the magnet portion has a structure in which magnets are arranged in a polygonal shape of a multiple of 2 or a polygonal shape. The rotation angle sensor according to claim 1, wherein a plurality of the magnetic detection elements are installed. It has a magnet part fixed to one end on the opposite side of the output side of the rotor rotation shaft, and can be mounted on the back side of the motor body with a control unit, and is arranged to face the magnet part A magnetic detection element is installed on the control board,
A brushless motor having a function of detecting a rotation angle of the rotor rotation shaft by the magnetic detection element. The brushless motor according to claim 5, wherein the magnet portion has a disk shape or a structure in which a magnet is disposed on the disk. The brushless motor according to claim 5, wherein the magnet part has a structure in which magnets are arranged in a polygonal shape of a multiple of 2 or a polygonal shape. The brushless motor according to claim 5, wherein a plurality of the magnetic detection elements are installed. An electric power steering apparatus, which is equipped with the brushless motor according to any one of claims 5 to 8, and applies an assist force to a steering system of a vehicle by a current command value calculated based on at least a steering torque. A vehicle equipped with the electric power steering device according to claim 9.

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