JP2007274849A - Electric power-steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power-steering device that executes abnormality diagnosis of a motor current detector, without rotating a motor, while vector-controlling a three-phase brushless motor at initial diagnosis. <P>SOLUTION: The abnormality of a current detector is detected from a motor current detection value detected, without rotating the motor, while utilizing that torque is not generated in the motor, even if a d-axis current component that is a magnetic-field component is flowing, if a q-axis current component that is a torque current component is zero, when vector-controlling of the motor is carried out. A d-axis detection current calculator 35 inputs an a-phase motor current ia, a b-phase motor current ib, a c-phase motor current ic, and rotor position information θ so as to convert each phase current detection value ia, ib, and ic into a d-axis detection current value id. An abnormality determining device 36 sets a d-axis current command value Id (a prescribed value) as a determining reference value, so as to determine whether the d-axis detection current value id is in the allowable range of the determining reference value. If the d-axis detection current value id lies in the allowable range, the current detectors 31, 32 are determined to be normal. If it is out of the allowable range, they are determined to be abnormal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus, and more particularly to an electric power steering apparatus capable of detecting a failure of a motor current detection means.

  An electric power steering device for a vehicle detects a steering torque and a vehicle speed generated in a steering shaft by operating a steering handle, and assists the steering force of the steering handle by driving a motor based on the detection signal. It is. Such an electric power steering apparatus is controlled by an electronic control unit composed of a CPU. The outline of the control is based on the steering torque detected by the torque sensor and the vehicle speed detected by the vehicle speed sensor. The magnitude of the current supplied to the motor is calculated, and the current supplied to the motor is controlled based on the calculation result.

  That is, when the steering wheel is operated and the steering torque is generated, the electronic control device supplies a large steering assist force when the detected vehicle speed is zero or low, and the detected vehicle speed is high. Can control the current supplied to the motor in accordance with the steering torque and the vehicle speed so as to supply a small steering assist force, thereby providing an optimum steering assist force according to the running state.

  In this type of device, feedback control is performed so that the current that actually flows through the motor matches the control target value of the motor current that is calculated based on the steering torque and vehicle speed. For this reason, the current that flows through the motor is detected. Motor current detecting means is provided.

  If the motor current detecting means described above fails, the accurate motor current cannot be measured. As a result, an excessive current flows to the motor to supply an excessive steering assist force, or the motor is not necessary. As a result, there is a problem that a sufficient amount of steering assist force cannot be supplied.

  Furthermore, if the motor rotates when a current is supplied to the motor and the operation of the motor current detecting means is confirmed, the steering handle rotates in a state where the motor shaft and the steering mechanism are coupled, and this is unexpected. An accident may occur.

  In response to this problem, the applicant is expected to apply a low voltage to the motor for a time sufficiently larger than the electrical time constant of the motor and sufficiently smaller than the mechanical time constant of the motor. Based on the current value and the motor current value detected by the motor current detection means, a failure determination means for determining a failure of the motor current detection means has been proposed (see Patent Document 1 and Patent Document 2).

In the above failure determination means, only for a limited time immediately after the engine start with the ignition key turned ON, that is, a time sufficiently larger than the electric time constant of the motor and sufficiently smaller than the mechanical time constant of the motor. A failure is determined by applying a low voltage to the motor, but this is necessary to prevent accidental accidents due to sudden rotation of the steering handle when the motor rotates immediately after starting the engine. It is.
Japanese Patent No. 3284785 Japanese Patent No. 3284786

  The failure determination means for determining the failure of the conventional motor current detection means described above was developed to be applied to a motor with a brush, and in order to apply to the current detection means of each phase of a three-phase brushless motor, Even though it is possible to configure based on the same concept, it is necessary to provide a plurality of current detection means corresponding to each phase, and any of the plurality of current detection means has a failure. If it occurs, troubles occur, and there is a disadvantage that the possibility of occurrence of a failure increases depending on the number of current detection means.

  In addition, the conventional failure determination means for determining the failure of the motor current detection means has a disadvantage that noise is generated during operation, but a plurality of current detection means are provided corresponding to each phase of the three-phase brushless motor. Sometimes, there is an inconvenience that the noise becomes louder.

  As in the case of the failure determination means for determining the failure of the conventional motor current detection means, the present invention can detect the failure of the motor current detection means for each phase of the three-phase brushless motor without rotating the motor immediately after starting the engine. It is an object of the present invention to provide a failure determination means that can solve the above inconvenience.

  The present invention solves the above-mentioned problems, and the invention of claim 1 is directed to a three-phase brushless motor having a permanent magnet and a field winding, and a d-axis that drives the motor based on at least steering torque and vehicle speed. Current command value calculating means for calculating the q-axis current command value, and a three-phase current command for calculating the phase current command value of each phase of the motor based on the d-axis and q-axis current command values and the motor rotation angle information Value calculating means, motor driving means for driving the motor based on a phase current command value for each phase of the motor, motor current detecting means for detecting a current flowing through the motor, and a rotational angle position of the motor A motor rotation angle detection means; an abnormality determination means for determining an abnormality of the motor current detection means; and a control device, wherein the control device is a permanent magnet according to a magnetic flux direction by the field winding and a motor rotation angle. When the the bundle direction is excited motor to be the same direction, an electric power steering apparatus characterized by detecting an abnormality in the motor current detecting means based on the detected motor current detection value.

  Then, the control device performs excitation based on the detected d-axis detection current value when exciting so that the magnetic flux direction by the field winding and the magnetic flux direction of the permanent magnet according to the motor rotation angle are the same direction. An abnormality of the motor current detection means is detected.

  The control device detects d when a predetermined voltage is applied to each phase of the motor so that the magnetic flux direction by the field winding and the magnetic flux direction of the permanent magnet according to the motor rotation angle are the same direction. An abnormality of the motor current detection means is detected based on the shaft detection current value.

  The control device includes abnormality determination current command value calculation means for calculating predetermined d-axis and q-axis current command values set in advance, and when the abnormality determination means detects an abnormality of the motor current detection means. Detects the abnormality of the motor current detection means based on the d-axis detection current value detected when the abnormality determination d-axis and q-axis current command values are output to the three-phase current command value calculation means And

  The motor current detection means is at least two phase motor current detection means for detecting a phase current flowing in the motor drive means for driving and controlling the motor.

  The motor current detecting means may be an all motor current detecting means for detecting a total current flowing through the motor driving means and at least two phase motor current detecting means for detecting a phase current of the motor.

  Then, the abnormality determination means detects an abnormality of the motor current detection means by comparing a predetermined determination reference value with the detected d-axis detection current value.

  The predetermined determination reference value used as a reference for abnormality determination by the abnormality determination unit is a predetermined d-axis current command value output from the abnormality determination current command value calculation unit.

  The predetermined determination reference value used as a reference for abnormality determination by the abnormality determination unit is based on a predetermined d-axis current command value set in advance and the rotation angle position of the motor detected by the motor rotation angle detection unit. Can be calculated.

  In addition, the predetermined determination reference value used as a reference for abnormality determination by the abnormality determination unit may be a predetermined value set in advance.

  In addition, the abnormality determination unit is configured to determine a motor based on a difference between the absolute value of the total motor current detection value detected by the total current detection unit and the absolute value of the phase motor current detection value detected by the phase motor current detection unit. An abnormality in the current detection means can also be determined.

  According to a twelfth aspect of the present invention, there is provided current command value calculating means for calculating a d-axis and q-axis current command value for controlling a three-phase brushless motor based on a steering torque and a vehicle speed, the d-axis and q-axis current command value, Three-phase current command value calculation means for calculating a phase current command value for each phase of the motor based on motor rotation angle information; and a motor drive means for driving and controlling the motor based on the phase current command value for each phase of the motor; A plurality of motor current detection means for detecting current flowing in the motor, motor rotation angle detection means for detecting the rotation angle position of the motor, and an abnormality for calculating predetermined d-axis and q-axis current command values set in advance A determination current command value calculation means; an abnormality determination means for determining an abnormality of the plurality of motor current detection means; and a control device, wherein the control device determines whether the motor current detection means is different from the abnormality determination means. Is detected, the abnormality determination d-axis and q-axis current command values are output to the three-phase current command value calculation means, and the motor current detection is performed based on the d-axis detection current value detected by the motor current detection means. An electric power steering apparatus characterized by detecting an abnormality of the means.

  According to a thirteenth aspect of the present invention, there is provided current command value calculating means for calculating a d-axis and q-axis current command value for controlling a three-phase brushless motor based on a steering torque and a vehicle speed, the d-axis and q-axis current command value, Three-phase current command value calculation means for calculating a phase current command value for each phase of the motor based on motor rotation angle information, motor drive means for driving the motor based on the phase current command value, and flow to the motor A plurality of motor current detection means for detecting current, a motor rotation angle detection means for detecting the rotation angle position of the motor, and a voltage of each phase of the motor based on predetermined d-axis and q-axis voltage command values set in advance An abnormality determination voltage command value calculation means for calculating a command value, an abnormality determination means for determining an abnormality of the plurality of motor current detection means, and a control device, wherein the control device uses the abnormality determination means. When detecting an abnormality in the motor current detecting means, the voltage command value of each phase of the motor output from the abnormality determining voltage command value calculating means is directly output to the motor driving means and detected by the motor current detecting means. An electric power steering apparatus that detects an abnormality of the motor current detection means based on a d-axis detection current value.

  The motor current detection means is motor current detection means for detecting two phase currents of the motor.

  The plurality of motor current detection means includes: a total motor current detection means for detecting a total current supplied from a power source to the motor drive means; and at least two phase motor current detection means for detecting a phase current of the motor. It may be composed of

  Then, the abnormality determination means detects an abnormality of the motor current detection means by comparing a predetermined determination reference value with the detected d-axis detection current value.

  The determination reference value used as a reference for abnormality determination by the abnormality determination unit is a predetermined d-axis current command value output from the abnormality determination current command value calculation unit.

  The determination reference value used as a reference for the abnormality determination by the abnormality determination means is calculated based on a predetermined d-axis current command value set in advance and the rotation angle position of the motor detected by the motor rotation angle detection means. May be.

  In addition, the determination reference value used as a reference for abnormality determination by the abnormality determination unit may be a predetermined value set in advance.

  In addition, the abnormality determination unit is configured to determine a motor based on a difference between the absolute value of the total motor current detection value detected by the total current detection unit and the absolute value of the phase motor current detection value detected by the phase motor current detection unit. You may determine abnormality of an electric current detection means.

  When the detected steering torque is equal to or less than a predetermined value or the motor rotation speed is equal to or less than the predetermined value, the control device performs an abnormality diagnosis by an abnormality determination unit.

  And the said control apparatus shall perform the abnormality diagnosis by an abnormality determination means in the initial diagnosis implemented before the steering assist operation immediately after engine starting is started.

  As described above, according to the present invention, when vector control of a three-phase brushless motor is performed, if the q-axis current component that is a torque current component is zero, the d-axis current component that is a magnetic flux vector component is flowing to the motor. By utilizing the fact that no torque is generated, it is possible to detect an abnormality in the motor current detection means from the motor current detection value detected without rotating the motor in the initial diagnosis mode immediately after the engine is started.

  In other words, in the present invention, when the motor is excited so that the magnetic flux direction by the field winding and the magnetic flux direction of the permanent magnet according to the motor rotation angle are the same direction, the above-described value is based on the detected motor current detection value. An abnormality of the motor current detection means is detected. Specifically, based on the d-axis detection current value detected when the abnormality determination d-axis and q-axis current command values are output to the phase current command value calculation means. To detect an abnormality in the motor current detecting means.

  Further, the voltage command value of each phase of the motor calculated based on the d-axis and q-axis voltage command values for abnormality determination is directly output to the motor drive means, and the motor current detection means of the motor current detection means is based on the detected d-axis detection current value. An abnormality is detected.

  According to these inventions, the q-axis current component is set to zero, and the abnormality of the motor current detection means is detected by the d-axis current component which is a magnetic flux vector component that does not generate torque in the motor. The current of each phase of the motor can be detected without rotating, and an abnormality of the motor current detecting means can be detected by comparing the detected current value with the determination reference value.

  In the present invention, the three-phase brushless motor is controlled by vector control. In the vector control, the current flowing through the three-phase brushless motor is decomposed into a q-axis current component which is a torque current component and a d-axis current component which is a magnetic field current component, and the q-axis current component which is a torque current component is converted into an output torque. It controls to be proportional. If the amplitude of the magnetic flux vector of the rotating magnetic field that is the d-axis current component is constant, the torque current vector that is the q-axis current component orthogonal to the magnetic field is proportional to the torque.

  If the q-axis current component, which is a torque current component, is zero (0), the motor can be used even if the d-axis current component, which is the magnetic flux vector component of the rotating magnetic field, is not zero (0) (that is, even if current is flowing). Since no torque is generated, the abnormality of the motor current detector can be detected from the state of the current flowing through the motor current detector without rotating the motor.

  Therefore, in the embodiment of the present invention, in the initial diagnosis mode for detecting a failure of the motor current detector immediately after the ignition key is turned ON, the torque current component of the current command value that is normally calculated from the steering torque or the like is used. The q-axis current command value Iq and the d-axis current command value Id that is the magnetic field current component are not used, the constant value Id (Id = 20 A as an example) is used as the d-axis current command value Id, and the torque component current component A certain q-axis current command value Iq is set to zero, and an abnormality of the motor current detector is detected by flowing a phase current to the motor without rotating the motor which is the object of the present invention.

  Embodiments of the present invention will be described below. FIG. 1 is a diagram for explaining an outline of the configuration of an electric power steering apparatus suitable for carrying out the present invention. A shaft 2 of a steering handle 1 passes through a reduction gear 4, universal joints 5a and 5b, and a pinion rack mechanism 7. Coupled to the steering wheel tyrod 8. A torque sensor 3 for detecting the steering torque of the steering handle 1 is provided on the shaft 2, and a motor 9, which is a three-phase brushless motor that assists the steering force, is coupled to the shaft 2 via the reduction gear 4. ing.

  Control device 10 for controlling the power steering device (20 in the first embodiment, 40 in the second embodiment, 60 in the third embodiment, 70 in the fourth embodiment, 80 in the fifth embodiment, 80 in the sixth embodiment 90) is supplied with an ignition key signal from the battery 14 via an ignition key (IG key) 11, and is also supplied with power from a parallel power supply line. The control device 10 (20, 40, 60, 70, 80, 90) calculates the current command value based on the steering torque detected by the torque sensor 3 and the vehicle speed detected by the vehicle speed sensor 12, and the calculation is performed. The current i supplied to the motor 9 is controlled based on the current command value.

  As described above, the control device 10 has a plurality of embodiments (20, 40, 60, 70, 80, 90) from the first embodiment to the sixth embodiment. This will be described below.

[First embodiment of control device]
FIG. 2 is a block diagram illustrating the configuration of the control device 20 of the first embodiment. Here, the configuration and operation when performing abnormality diagnosis of the motor current detector that is executed in the initial diagnosis mode immediately after the ignition key is turned on will be described.

  The steering torque T detected by the torque sensor 3 (see FIG. 1) and the vehicle speed V detected by the vehicle speed sensor 12 are input to the characteristic compensator 21, and when the vehicle speed V exceeds a predetermined value, the steering torque T is a constant value. Is compensated to output. In the characteristic compensator 21, a current command value Iref corresponding to the steering torque T with the vehicle speed V as a parameter is stored in the memory.

  In the current command value calculator 22, the q-axis current command value Iq, which is a torque current component, and the d-axis current command value Id, which is a magnetic field current component, are based on the input characteristic-compensated current command value Iref. Calculated with an expression.

d-axis current command value Id = f (Iref, ω)
q-axis current command value Iq = {2/3 (Tref · ω−ed · Id)} / eq
However. Tref = Kt · Iref,
Kt: motor torque coefficient, ω: motor speed,
ed: d-axis counter electromotive voltage, eq: q-axis counter electromotive voltage The calculated q-axis current command value Iq and d-axis current command value Id are input to the three-phase current command value calculator 23 via a switch SWA described later. Is done.

  The three-phase current command value calculator 23 indicates the input q-axis current command value Iq and d-axis current command value Id, and the rotational angle position of the motor rotor output from the motor rotor position detector 33 described later. Based on the rotor position information θ, phase current command values Ia, Ib, and Ic for commanding currents to be supplied to the respective phases of the three-phase brushless motor are calculated.

  In the normal operation control mode, the current command value calculator 22 outputs a q-axis current command value Iq that is a torque current component and a d-axis current command value Id that is a magnetic field current component. In the initial diagnosis mode executed immediately after the ignition key is turned ON, the abnormality determination current command value calculator 24 receives the q-axis current command value Iq, which is a torque current component for abnormality determination, and the magnetic field current component. The d-axis current command value Id is output.

  In the normal operation control mode, the q-axis current command value Iq and the d-axis current command value Id output from the current command value calculator 22 by switching the switch SWA are transferred to the three-phase current command value calculator 23. Entered.

  In the initial diagnosis mode, the abnormality determination q-axis current command value Iq and the abnormality determination d-axis current command value Id output from the abnormality determination current command value calculator 24 by the switching of the switch SWA are as follows. It is input to the three-phase current command value calculator 23. Here, the q-axis current command value Iq for abnormality determination is zero (Iq = 0), and the d-axis current command value Id is a constant value (for example, Id = 20 A). By setting the q-axis current command value Iq to zero (Iq = 0), the phase current flows through the motor without rotating the motor, which is the object of the present invention, and an abnormality in the motor current detector of the motor drive control means is detected. It can be done.

  The adders 25a, 25b, and 25c are connected to the phase current command values Ia, Ib, and Ic of each phase output from the three-phase current command value calculator 23, and the a phase output from the a phase motor current detector 31 described later. The motor current detection value ia, the c-phase motor current detection value ic output from the c-phase motor current detector 32, and the b-phase motor current detection value ib output from the subtractor 34 are fed back to calculate the respective differences. And output to the proportional-plus-integral calculator 26. The subtractor 34 calculates and outputs a b-phase motor current detection value ib (ib = −ia−ic) from the a-phase motor current detection value ia and the c-phase motor current detection value ic. That is, the relationship (ia + ib + ic = 0) is established among the a-phase motor current detection value ia, the b-phase motor current detection value ib, and the c-phase motor current detection value ic.

  The proportional-plus-integral calculator 26 is a difference (Ia-ia), (Ib-ib), or (Ic-ic) value between each phase current command value calculated by the adders 25a to 25c and each phase motor current detection value. A PI operation for calculating a proportional value and an integral value is performed on the motor and output to the motor drive circuit 27.

  The motor drive circuit 27 outputs a pulse signal (PWM signal) that drives the switching elements (six) of the inverter 28 based on the output from the proportional-plus-integral calculator 26. Based on the input pulse signal, the switching elements (six) of the inverter 28 are ON / OFF controlled, and the electric power supplied from the battery 14 sequentially excites the magnetic poles of the stator of the motor 9 in a predetermined order to rotate the magnetic field. And the rotor of the motor 9 is rotated.

  The motor 9 is provided with a motor rotor position detector 33 for detecting rotor position information θ, an a-phase motor current detector 31 for detecting a motor current ia for exciting an a-phase magnetic pole, and a c-phase motor current detector 31. A c-phase motor current detector 32 for detecting a motor current ic for exciting the magnetic poles is disposed, and a-phase motor current ia and c-phase motor current ic are detected, respectively.

  The a-phase motor current ia, b-phase motor current ib, and c-phase motor current ic are fed back to the adders 25a, 25b, and 25c, respectively.

  The d-axis detection current calculator 35 receives the a-phase motor current ia, the b-phase motor current ib, the c-phase motor current ic, and the rotor position information θ output from the motor rotor position detector 33, and inputs each phase. An operation for converting the current detection values (a-phase motor current ia, b-phase motor current ib, c-phase motor current ic) into the d-axis detection current value id is performed.

  The abnormality determiner 36 uses the d-axis current command value Id output from the abnormality determination current command value calculator 24 as a determination reference value, and determines the d-axis detected current value id calculated by the d-axis detected current calculator 35. It is determined whether or not it is within a predetermined allowable range centered on a d-axis current command value Id (for example, 20 A) that is a reference value.

  When the initial diagnosis mode is set, the output of the abnormality determination current command value calculator 29 is output to the three-phase current command value calculator 23 by switching the switch SWA. The abnormality determiner 36 determines whether or not the calculated d-axis detection current value id is within a predetermined allowable range centered on the determination reference value.

  When the d-axis detection current value id is within an allowable range centered on the predetermined determination reference value, the a-phase motor current detector 31 and the c-phase motor current detector 32 are determined to be normal, and the determination reference value Is outside the allowable range, the a-phase motor current detector 31 and / or the c-phase motor current detector 32 are determined to be abnormal. When it is determined that there is an abnormality, the failure signal Er is output to a fail safe processor (not shown), and fail safe processing for prohibiting steering assistance by the motor 9 is performed.

  For example, as illustrated above, that is, when the determination reference value Id is 20A, when the d-axis detection current value id is within the allowable ranges 18A to 22A, which is the allowable range of the determination reference value, the a-phase motor When the current detector 31 and the c-phase motor current detector 32 are normal and outside the allowable ranges 18A to 22A, the a-phase motor current detector 31 and / or the c-phase motor current detector 32 are determined to be abnormal.

[Second Embodiment of Control Device]
FIG. 3 is a block diagram illustrating the configuration of the control device 40 of the second embodiment. Here, the configuration and operation when performing abnormality diagnosis of the motor current detector that is executed in the initial diagnosis mode immediately after the ignition key is turned on will be described.

  The control device 40 of the second embodiment has similar components to the control device 20 of the first embodiment shown in FIG. 2, and only the configuration of the portion related to the abnormality diagnosis of the current detector is different. The members common to the control device 20 of the embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and different portions relating to abnormality diagnosis of the current detector will be described.

  In the second embodiment, a configuration corresponding to the d-axis detection current calculator 35 of the first embodiment is not provided, but instead, an abnormality determination value calculator 37 and an abnormality determiner 38 are provided.

  The abnormality determination value calculator 37 includes a d-axis current command value Id (for example, 20A) that is a magnetic field current component output from the abnormality determination current command value calculator 24 as a predetermined constant value, and a motor rotor position detector. The rotor position information θ output from 33 is input, and the determination reference value iae for the a-phase motor current and the determination reference value ice for the c-phase motor current are calculated.

  The abnormality determiner 38 compares the a-phase motor current detection value ia with the a-phase motor current determination reference value iae, and the c-phase motor current detection value ic and the above-described c-phase motor current determination reference value. Compare with ice.

  The a-phase motor current detector 31 is normal when the a-phase motor current detection value ia is within the allowable range centered on the determination reference value iae for the a-phase motor current, and the a-phase motor current detector when it is outside the allowable range. 31 is determined to be abnormal. The c-phase motor current detector 32 is normal when the detected c-phase motor current value ic is within an allowable range centered on the determination reference value ice of the c-phase motor current, and the c-phase motor current is detected when the detected value is outside the allowable range. The detector 32 determines that it is abnormal.

  When it is determined that the a-phase motor current detector 31 or the c-phase motor current detector 32 is abnormal, a fail-safe process is performed in which a failure signal Er is output to a fail-safe processor (not shown) and steering assist by the motor 9 is prohibited. Do.

  The a-phase motor current determination reference value iae and the c-phase motor current determination reference value ice are calculated using the following equations.

a-phase motor current judgment reference value iae = cos θ × Id
c-phase motor current determination reference value ice = cos (θ + 2 / 3θ) × Id
Where θ: Rotor position information
Id: d-axis current command value For example, when the d-axis current command value Id is 20 A and the rotor position information θ indicating the magnetic pole position of the motor rotor is 45 °, the a-phase motor current determination reference value iae = cos ( 45 °) × 20 = 14A
C-phase motor current determination reference value ice = cos (45 ° + 120 °) × 20 = 19 A
It becomes.

  If the allowable range of the determination reference value is ± 2A, when the a-phase motor current detection value is in the range of 12A to 16A, the a-phase motor current detector 31 is normal, and the a-phase motor current detection value is 12A to 16A. When out of the range, the a-phase motor current detector 31 determines that there is an abnormality. Similarly, the c-phase motor current detector 32 is normal when the c-phase motor current detection value is in the range of 17A to 21A, and the c-phase motor current detection is when the c-phase motor current detection value is outside the range of 17A to 21A. The device 32 determines that it is abnormal.

[Third embodiment of control device]
FIG. 4 is a block diagram illustrating the configuration of the control device 60 of the third embodiment. Here, the configuration and operation when performing abnormality diagnosis of the motor current detector that is executed in the initial diagnosis mode immediately after the ignition key is turned on will be described.

  The control device 60 of the third embodiment has similar components to the control device 20 of the first embodiment shown in FIG. 2, and only the configuration of the portion related to abnormality diagnosis of the current detector is different. The members common to the control device 20 of the embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and different portions relating to abnormality diagnosis of the current detector will be described.

  The third embodiment is not provided with a configuration corresponding to the d-axis current detector 35 of the first embodiment, is provided with an abnormality determination device 50, and is provided in the first and second embodiments. A total motor current detector 30 that detects the total current idc flowing through the motor 9 that is not connected is disposed between the battery 14 and the inverter 28.

  FIG. 5 is a block diagram for explaining the configuration of the abnormality detector 50 of the third embodiment. The abnormality detector 50 includes an a-phase motor current detection value ia detected by the a-phase motor current detector 31, a c-phase motor current detection value ic detected by the c-phase motor current detector 32, and a total motor current detection. The total current detection value idc detected by the detector 30 is input. Then, the subtractor 34 calculates and outputs a b-phase motor current detection value ib (ib = −ia−ic) from the a-phase motor current detection value ia and the c-phase motor current detection value ic.

  Next, in the absolute value calculation units 52, 53, 54, and 55, the absolute value | ia | of the a-phase motor current detection value ia, the absolute value | ib | of the b-phase motor current detection value ib, and the c-phase motor current detection, respectively. The absolute value | ic | of the value ic and the absolute value | idc | of the total motor current detection value idc are calculated.

  The absolute value of the calculated a-phase motor current detection value ia, the absolute value of the b-phase motor current detection value ib, and the absolute value of the c-phase motor current detection value ic are input to the maximum value detection unit 56, and the phase current detection value The maximum value | imax | (the maximum value among | ia |, | ib |, | ic |) is output.

  In the subtractor 57, a deviation Δi (= | idc | − | imax |) between the maximum value | imax | of the phase current absolute value output from the maximum value detecting unit 56 and the absolute value | idc | Further, the absolute value calculation unit 58 calculates the absolute value | Δi | of the deviation.

  Next, the comparator 59a compares the absolute value | Δi | of the deviation with a preset criterion value Sr stored in the memory 59b. When the absolute value | Δi | of the deviation is larger than the determination reference value Sr, the total motor current detector 30, the a-phase motor current detector 31 that detects the a-phase motor current, and the c-phase motor current that detects the c-phase motor current It is determined that at least one current detector of the detector 32 is abnormal, and if the absolute value of deviation | Δi | is smaller than the determination reference value Sr, it is determined that all the motor current detectors are normal.

  When it is determined that the all-motor current detector 30, the a-phase motor current detector 31 or the c-phase motor current detector 32 is abnormal, a failure signal Er is output to a fail-safe processor (not shown) to assist steering by the motor 9. Fail-safe processing is prohibited.

  The determination reference value Sr takes into account manufacturing variations of control devices, motors, harnesses, etc., so that the abnormality of the motor current detector can be detected reliably and no false detection is detected. A constant value is used regardless of the rotor position information θ). For example, when the determination reference value Sr = 10 A and the deviation absolute value | Δi | is smaller than 10 A, it is determined that all the motor current detectors 30, 31, 32 are normal.

[Fourth Embodiment of Control Device]
FIG. 6 is a block diagram illustrating the configuration of the control device 70 of the fourth embodiment. Here, the configuration and operation when performing abnormality diagnosis of the motor current detector that is executed in the initial diagnosis mode immediately after the ignition key is turned on will be described.

  The control device 70 of the fourth embodiment has a similar part to the control device 20 of the first embodiment shown in FIG. 2, does not have the switch SWA of the first embodiment, and has a current for abnormality determination of the first embodiment. In place of the command value calculator 24, an abnormality determination voltage command value calculator 29 is arranged, and a switch SWB is arranged on the output side of the proportional-plus-integral calculator 26. The output of the value calculator 29 is input to the motor drive circuit 27 via the switch SWB.

  Since other configurations are the same as those of the control device 20 of the first embodiment, members common to the control device 20 of the first embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and different portions are described. To do.

  The steering torque T detected by the torque sensor 3 (see FIG. 1) and the vehicle speed V detected by the vehicle speed sensor 12 are input to the characteristic compensator 21, and when the vehicle speed V exceeds a predetermined value, the steering torque T is a constant value. Is compensated to output. In the characteristic compensator 21, a current command value Iref corresponding to the steering torque T with the vehicle speed V as a parameter is stored in the memory.

  The current command value calculator 22 calculates a q-axis current command value Iq, which is a torque current component, and a d-axis current command value Id, which is a magnetic field current component, based on the input characteristic-compensated current command value Iref. The calculated q-axis current command value Iq and d-axis current command value Id are input to the three-phase current command value calculator 23.

  The three-phase current command value calculator 23 indicates the input q-axis current command value Iq and d-axis current command value Id, and the rotational angle position of the motor rotor output from the motor rotor position detector 33 described later. Based on the rotor position information θ, phase current command values Ia, Ib, and Ic for commanding currents to be supplied to the respective phases of the three-phase brushless motor are calculated.

  The adders 25a, 25b, and 25c respectively add a phase current command value Ia, Ib, and Ic output from the three-phase current command value calculator 23 to an a-phase motor current detector 31 and a c-phase motor current detection described later. The phase motor current detection values ia, ib, and ic of the phases a, b, and c are output from the counter 32 and the subtractor 34 that calculates the b-phase current value, and the difference between them is calculated. And output to the proportional-plus-integral calculator 26. The subtractor 34 calculates and outputs a b-phase motor current detection value ib (ib = −ia−ic) from the a-phase motor current detection value ia and the c-phase motor current detection value ic.

  The proportional-plus-integral calculator 26 is a difference (Ia-ia), (Ib-ib), or (Ic-ic) value between each phase current command value calculated by the adders 25a to 25c and each phase motor current detection value. A PI operation for calculating a proportional value and an integral value is performed, and the obtained phase voltage control values are output to the motor drive circuit 27 via a switch SWB described later.

  The abnormality determination voltage command value calculator 29 is used for abnormality determination based on the q-axis current command value Iq used for abnormality determination, the abnormality determination d-axis current command value Id, and the rotor position information θ. In addition to calculating the a-phase motor voltage command value, b-phase motor voltage command value, and c-phase motor voltage command value to be output to the motor drive circuit 27 via the switch SWB, the d-axis current command value Id for abnormality determination is also output. It outputs to the abnormality determination device 36 as a determination reference value. Here, the abnormality determination d-axis current command value Id is a constant value (Id = 20 A as an example).

  When the a-phase motor voltage command value, the b-phase motor voltage command value, and the c-phase motor voltage command value are calculated by the abnormality determination voltage command value calculator 29, zero (Iq = 0) is used as the q-axis current command value Iq. By doing so, the phase current can be supplied to the motor without rotating the motor which is the object of the present invention, and an abnormality of the motor current detector of the motor drive control means can be detected.

  In the normal operation control mode, the switch SWB outputs the output of the proportional-plus-integral calculator 26 to the motor drive circuit 27 by switching the switch SWB. In the initial diagnosis mode, the switch SWB switches the switch SWB. Thus, the output of the abnormality determination voltage command value calculator 29 is directly output to the motor drive circuit 27.

  The motor drive circuit 27 is a pulse signal (PWM signal) that drives the switching elements (six) of the inverter 28 based on the inputted a-phase motor voltage command value, b-phase motor voltage command value, and c-phase motor voltage command value. Is output. Based on the input pulse signal, the switching elements (six) of the inverter 28 are ON / OFF controlled, and the electric power supplied from the battery 14 sequentially excites the magnetic poles of the stator of the motor 9 in a predetermined order to rotate the magnetic field. And the rotor of the motor 9 is rotated.

  The motor 9 is provided with a motor rotor position detector 33 for detecting rotor position information θ, an a-phase motor current detector 31 for detecting a motor current ia for exciting an a-phase magnetic pole, and a c-phase motor current detector 31. A c-phase motor current detector 32 for detecting a motor current ic for exciting the magnetic poles is disposed, and a-phase motor current ia and c-phase motor current ic are detected, respectively.

  The a-phase motor current ia, b-phase motor current ib, and c-phase motor current ic are fed back to the adders 25a, 25b, and 25c, respectively.

  The d-axis detection current calculator 35 receives the a-phase motor current ia, the b-phase motor current ib, the c-phase motor current ic, and the rotor position information θ as input to each phase current detection value (a-phase motor current ia, b-phase motor). An operation for converting the current ib and the c-phase motor current ic) to the d-axis detected current value id is performed.

  The abnormality determiner 36 uses the d-axis current command value Id output from the abnormality determination voltage command value calculator 29 as a determination reference value, and determines the d-axis detected current value id calculated by the d-axis detected current calculator 35. It is determined whether or not it is within a predetermined allowable range centered on a d-axis current command value Id (for example, 20 A) that is a reference value.

  When the initial diagnosis mode is set, the output of the abnormality determination voltage command value calculator 29 is directly output to the motor drive circuit 27 by switching the switch SWB. The abnormality determiner 36 determines whether or not the calculated d-axis detection current value id is within a predetermined allowable range centered on the determination reference value.

  When the d-axis detection current value id is within a predetermined allowable range, the a-phase motor current detector 31 and the c-phase motor current detector 32 are determined to be normal, and when outside the predetermined allowable range, the a-phase motor The current detector 31 and / or the c-phase motor current detector 32 are determined to be abnormal. When it is determined that there is an abnormality, the failure signal Er is output to a fail safe processor (not shown), and fail safe processing for prohibiting steering assistance by the motor 9 is performed.

  For example, as illustrated above, that is, when the determination reference value Id is 20 A, the a-phase motor current detector 31 when the d-axis detection current value id is within the permissible ranges 18A to 22A. And when the c-phase motor current detector 32 is normal and outside the allowable ranges 18A to 22A, the a-phase motor current detector 31 and / or the c-phase motor current detector 32 are determined to be abnormal.

[Fifth embodiment of control device]
FIG. 7 is a block diagram illustrating the configuration of the control device 80 of the fifth embodiment. Here, the configuration and operation when performing abnormality diagnosis of the motor current detector that is executed in the initial diagnosis mode immediately after the ignition key is turned on will be described.

  The control device 80 of the fifth embodiment has similar components to the control device 70 of the fourth embodiment shown in FIG. 6, and only the configuration of the portion relating to abnormality diagnosis of the current detector is different. Since the configuration of the part relating to the abnormality diagnosis of the current detector is the same as the configuration of the second embodiment, common members are denoted by the same reference numerals and detailed description thereof is omitted, and abnormality diagnosis of the current detector is performed. The difference part about is described.

  In the fifth embodiment, a configuration corresponding to the d-axis detection current calculator 35 of the fourth embodiment is not provided, but instead, an abnormality determination value calculator 37 and an abnormality determiner 38 are provided.

  The abnormality determination value calculator 37 includes a d-axis current command value Id (for example, 20A) that is a magnetic field current component output from the abnormality determination voltage command value calculator 29 as a predetermined constant value, and a motor rotor position detector. The rotor position information θ output from 33 is input, and the determination reference value iae for the a-phase motor current and the determination reference value ice for the c-phase motor current are calculated.

  The abnormality determiner 38 compares the a-phase motor current detection value ia with the a-phase motor current determination reference value iae, and the c-phase motor current detection value ic and the above-described c-phase motor current determination reference value. Compare with ice.

  The a-phase motor current detector 31 is normal when the a-phase motor current detection value ia is within the allowable range centered on the determination reference value iae for the a-phase motor current, and the a-phase motor current detector when it is outside the allowable range. 31 is determined to be abnormal. The c-phase motor current detector 32 is normal when the detected c-phase motor current value ic is within an allowable range centered on the determination reference value ice of the c-phase motor current, and the c-phase motor current is detected when the detected value is outside the allowable range. The detector 32 determines that it is abnormal.

  When it is determined that the a-phase motor current detector 31 or the c-phase motor current detector 32 is abnormal, a fail-safe process is performed in which a failure signal Er is output to a fail-safe processor (not shown) and steering assist by the motor 9 is prohibited. Do.

  Since the a-phase motor current determination reference value iae and the c-phase motor current determination reference value ice are the same as those described in the second embodiment, description thereof is omitted here.

[Sixth embodiment of control device]
FIG. 8 is a block diagram illustrating the configuration of the control device 90 of the sixth embodiment. Here, the configuration and operation when performing abnormality diagnosis of the motor current detector that is executed in the initial diagnosis mode immediately after the ignition key is turned on will be described.

  The control device 90 of the sixth embodiment has similar components to the control device 70 of the fourth embodiment shown in FIG. 6, and only the configuration of the portion related to the abnormality diagnosis of the current detector is different. Since the configuration of the part relating to the abnormality diagnosis of the current detector is the same as the configuration of the third embodiment, the same reference numerals are given to the common members and the detailed description is omitted, and the abnormality diagnosis of the current detector is performed. The difference part about is described.

  In the sixth embodiment, a configuration corresponding to the d-axis current detector 35 of the fourth embodiment is not provided, an abnormality determination device 50 is provided, and a motor not provided in the fourth embodiment. 9 is disposed between the battery 14 and the inverter 28. The total motor current detector 30 for detecting the total current idc flowing through

  The configuration and operation of the abnormality detector 50 of the sixth embodiment are the same as the configuration and operation of the abnormality detector 50 of the third embodiment described above with reference to FIG. .

  When it is determined that the all-motor current detector 30, the a-phase motor current detector 31 or the c-phase motor current detector 32 is abnormal, a failure signal Er is output to a fail-safe processor (not shown) to assist steering by the motor 9. Fail-safe processing is prohibited.

  In the fourth to sixth embodiments described above, the abnormality determination voltage command value calculator 29 uses the q-axis current command value Iq used for abnormality determination, the abnormality determination d-axis current command value Id, and the motor 9. The a-phase motor voltage command value Ea, b-phase motor voltage command value Eb, and c-phase motor voltage command value Ec used for abnormality determination are calculated on the basis of the rotor position information θ of the motor, and the motor is passed through the switch SWB. A configuration for directly outputting to the drive circuit 27 is provided.

  In the configurations of the first to third embodiments, since the proportional-plus-integral calculator 26 controls the d-axis current to be a predetermined value, for example, even when a failure such as an inter-phase short circuit in which the motor resistance is halved occurs. The motor current detector detects a predetermined value of current and cannot detect an abnormality. However, in the fourth to sixth embodiments, each phase motor voltage command value (a phase motor voltage command value Ea, b phase motor voltage command value Eb, c phase motor) output from the abnormality determination voltage command value calculator 29 is used. Since the voltage command value Ec) is directly input to the motor drive circuit, for example, when a failure such as a short circuit between phases that reduces the motor resistance by half occurs, the motor current flows twice as long as normal, and an abnormality is detected. be able to. However, in this configuration, an appropriate determination reference value is set because there is a risk of erroneous determination unless the allowable range of the determination reference value for determining an abnormality in the motor current is set.

  In an initial diagnosis mode immediately after the ignition key is turned on, an electric power steering device for a vehicle that diagnoses an abnormality of a motor current detector, and when a three-phase brushless motor is vector-controlled, a torque current component q If the shaft current component is zero, the fact that no torque is generated in the motor even if the d-axis current component, which is a magnetic field component, flows can be used to detect the current from the detected motor current detection value without rotating the motor. This is an electric power steering device for diagnosing the abnormality of the device.

BRIEF DESCRIPTION OF THE DRAWINGS The figure explaining the outline of a structure of the electric power steering apparatus suitable for implementing invention. The block diagram explaining the structure of the control apparatus of 1st Example. The block diagram explaining the structure of the control apparatus of 2nd Example. The block diagram explaining the structure of the control apparatus of 3rd Example. The block diagram explaining the structure of the abnormality detector of 3rd Example. The block diagram explaining the structure of the control apparatus of 4th Example. The block diagram explaining the structure of the control apparatus of 5th Example. The block diagram explaining the structure of the control apparatus of 6th Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Axis 3 Torque sensor 4 Reduction gear 5a, 5b Universal joint 7 Pinion rack mechanism 8 Tyrode 9 Motor (three-phase brushless motor)
10, 20, 40, 60, 70, 80, 90 Controller 11 Ignition key (IG key)
12 vehicle speed sensor 14 battery 21 characteristic compensator 22 current command value calculator 23 three-phase current command value calculator 24 current command value calculator for abnormality determination 25a, 25b, 25c adder 26 proportional integral calculator 27 motor drive circuit 28 inverter 29 Abnormality determination voltage command value calculator 31 a-phase motor current detector 32 c-phase motor current detector 33 motor rotor position detector 35 d-axis detection current calculator 36 abnormality determiner 37 abnormality determination value calculator 38 abnormality determination 50 Abnormality determination unit 51 Subtractor 52, 53, 54, 55 Absolute value calculation unit 56 Maximum value detection unit 57 Subtractor 58 Absolute value calculation unit 59a Comparator 59b Memory SWA, SWB switcher

Claims (22)

A three-phase brushless motor with permanent magnets and field windings;
Current command value calculation means for calculating d-axis and q-axis current command values for driving the motor based on at least steering torque and vehicle speed;
Three-phase current command value calculating means for calculating a phase current command value of each phase of the motor based on the d-axis and q-axis current command values and rotation angle information of the motor;
Motor driving means for driving the motor based on a phase current command value of each phase of the motor;
Motor current detecting means for detecting current flowing in the motor;
Motor rotation angle detection means for detecting the rotation angle position of the motor;
An abnormality determining means for determining an abnormality of the motor current detecting means;
A control device,
When the motor is excited so that the direction of the magnetic flux by the field winding and the direction of the magnetic flux of the permanent magnet according to the motor rotation angle are the same direction, the control device is configured to detect the motor based on the detected motor current value. An electric power steering apparatus characterized by detecting an abnormality in current detection means. The controller controls the motor current based on the detected d-axis detection current value when excitation is performed so that the magnetic flux direction by the field winding and the magnetic flux direction of the permanent magnet according to the motor rotation angle are the same direction. The electric power steering apparatus according to claim 1, wherein an abnormality of the detecting means is detected. The control device detects a d-axis detected when a predetermined voltage is applied to each phase of the motor so that the magnetic flux direction by the field winding and the magnetic flux direction of the permanent magnet according to the motor rotation angle are the same direction. 2. The electric power steering apparatus according to claim 1, wherein an abnormality of the motor current detection means is detected based on a current value. The control device includes abnormality determination current command value calculation means for calculating predetermined d-axis and q-axis current command values set in advance, and when detecting abnormality of the motor current detection means by the abnormality determination means, An abnormality of the motor current detection means is detected based on a d-axis detection current value detected when the abnormality determination d-axis and q-axis current command values are output to the three-phase current command value calculation means. The electric power steering apparatus according to claim 1. 5. The motor current detection unit according to claim 1, wherein the motor current detection unit is at least two phase motor current detection units that detect a phase current flowing in a motor drive unit that drives and controls the motor. Electric power steering device. The motor current detection means is a total motor current detection means for detecting a total current flowing through the motor driving means, and at least two phase motor current detection means for detecting a phase current of the motor. The electric power steering apparatus according to any one of 1 to 4. 5. The electric power according to claim 1, wherein the abnormality determination unit detects an abnormality of the motor current detection unit by comparing a predetermined determination reference value with a detected d-axis detection current value. 6. Steering device. The predetermined determination reference value used as a reference for abnormality determination by the abnormality determination unit is a predetermined d-axis current command value output from the abnormality determination current command value calculation unit. Electric power steering device. The predetermined determination reference value used as a reference for abnormality determination by the abnormality determination unit is calculated based on a predetermined d-axis current command value set in advance and the rotation angle position of the motor detected by the motor rotation angle detection unit. The electric power steering apparatus according to claim 7. The electric power steering apparatus according to claim 7, wherein the predetermined determination reference value used as a reference for abnormality determination by the abnormality determination unit is a predetermined value set in advance. The abnormality determination means detects the motor current based on the difference between the absolute value of the total motor current detection value detected by the total current detection means and the absolute value of the phase motor current detection value detected by the phase motor current detection means. 5. The electric power steering apparatus according to claim 1, wherein abnormality of the means is determined. Current command value calculating means for calculating d-axis and q-axis current command values for controlling the three-phase brushless motor based on the steering torque and the vehicle speed;
Three-phase current command value calculating means for calculating a phase current command value for each phase of the motor based on the d-axis and q-axis current command values and motor rotation angle information;
Motor driving means for driving and controlling the motor based on a phase current command value of each phase of the motor;
A plurality of motor current detecting means for detecting a current flowing through the motor;
Motor rotation angle detection means for detecting the rotation angle position of the motor;
An abnormality determination current command value calculating means for calculating predetermined d-axis and q-axis current command values set in advance;
An abnormality determining means for determining an abnormality of the plurality of motor current detecting means;
A control device,
When the abnormality determination unit detects an abnormality in the motor current detection unit, the control device outputs the abnormality determination d-axis and q-axis current command values to a three-phase current command value calculation unit, and detects the motor current detection. An electric power steering device characterized by detecting an abnormality of the motor current detection means based on the d-axis detection current value detected by the means. Current command value calculating means for calculating d-axis and q-axis current command values for controlling the three-phase brushless motor based on the steering torque and the vehicle speed;
Three-phase current command value calculating means for calculating a phase current command value for each phase of the motor based on the d-axis and q-axis current command values and motor rotation angle information;
Motor driving means for driving the motor based on the phase current command value;
A plurality of motor current detecting means for detecting a current flowing through the motor;
Motor rotation angle detection means for detecting the rotation angle position of the motor;
An abnormality determination voltage command value calculating means for calculating a voltage command value of each phase of the motor based on predetermined d-axis and q-axis voltage command values set in advance;
An abnormality determining means for determining an abnormality of the plurality of motor current detecting means;
A control device,
When the abnormality determining means detects an abnormality of the motor current detecting means, the control device directly outputs the voltage command value of each phase of the motor output from the abnormality determining voltage command value calculating means to the motor driving means. An electric power steering apparatus that detects an abnormality of the motor current detection means based on a d-axis detection current value detected by the motor current detection means. The electric power steering apparatus according to claim 12 or 13, wherein the motor current detection means is motor current detection means for detecting two phase currents of the motor. The plurality of motor current detection means includes: a total motor current detection means for detecting a total current supplied from a power source to the motor drive means; and at least two phase motor current detection means for detecting a phase current of the motor. The electric power steering apparatus according to claim 12 or 13, wherein the electric power steering apparatus is configured. The electric power according to claim 12 or 13, wherein the abnormality determination means detects an abnormality of the motor current detection means by comparing a predetermined determination reference value with a detected d-axis detection current value. Steering device. 17. The electric motor according to claim 16, wherein the determination reference value used as a reference for abnormality determination by the abnormality determination unit is a predetermined d-axis current command value output from the abnormality determination current command value calculation unit. Power steering device. A determination reference value used as a reference for abnormality determination by the abnormality determination unit is calculated based on a predetermined d-axis current command value set in advance and the rotation angle position of the motor detected by the motor rotation angle detection unit. The electric power steering apparatus according to claim 16. The electric power steering apparatus according to claim 16, wherein a determination reference value used as a reference for abnormality determination by the abnormality determination unit is a predetermined value set in advance. The abnormality determination means detects the motor current based on the difference between the absolute value of the total motor current detection value detected by the total current detection means and the absolute value of the phase motor current detection value detected by the phase motor current detection means. 14. The electric power steering apparatus according to claim 12, wherein abnormality of the means is determined. 21. The controller according to any one of claims 1 to 20, wherein when the detected steering torque is equal to or less than a predetermined value or when the motor rotation speed is equal to or less than a predetermined value, the controller performs an abnormality diagnosis by an abnormality determination unit. The electric power steering device described in 1. 21. The control device according to claim 1, wherein the control device performs an abnormality diagnosis by an abnormality determination unit in an initial diagnosis performed before the steering assist operation immediately after the engine is started. The electric power steering apparatus as described.

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