JP5991264B2 - Electric power steering device - Google Patents

Description

  The present disclosure relates to an electric power steering apparatus.

  Conventionally, an AC servo motor having a rotor having a plurality of pairs of magnetic poles, a stator having two sets of three-phase windings wound on the circumference at 60 degrees apart from each other, and each of the three-phase windings. 2. Description of the Related Art An AC servo motor drive device is known that has a double redundant configuration using two sets of control devices that individually supply three-phase alternating currents to the wires (see, for example, Patent Document 1). . In this apparatus, during normal operation, two sets of three-phase windings are energized to generate a resultant torque in the motor.

  Further, a disc brake main body that generates a braking force by the operation of the motor, a three-phase winding of the motor, and a battery, which generate currents having different phases according to a pulse signal from the controller, A motor driver that operates the motor by supplying each of the three-phase windings, and the motor driver includes a series element body formed by connecting two switching elements that are turned on and off by the pulse signal in series. There are three sets corresponding to each winding of the wire, and the electric disk brake device is configured by interposing the three sets of series element bodies between the poles of the battery, An electric disc brake device that measures the voltage of the three-phase winding during a dead time provided so that two switching elements are not turned on at the same time, and detects a failure based on the measured voltage value Known (e.g., see Patent Document 2).

  An inverter that converts DC power into three-phase AC power, a permanent magnet synchronous motor that is connected to a three-phase AC output terminal of the inverter via a three-phase output line, and the inverter and the permanent magnet synchronous motor An electric vehicle control device having an opening means for opening the three-phase output line in between and a control means for closing the opening means in a normal state and opening the opening means when a failure of the inverter is detected is known. (For example, see Patent Document 3).

JP 2003-102189 A Japanese Patent Laid-Open No. 2002-058288 Japanese Unexamined Patent Publication No. 08-182105

  However, in the configuration described in Patent Document 1 above, normally, two sets of three-phase windings are energized at half the rated operation, and the resultant torque is generated in the motor. When an abnormality occurs suddenly in one of the systems, the assist torque may be temporarily reduced (50%).

  Therefore, the present disclosure aims to provide an electric power steering device that can determine whether or not there is an abnormality in the two windings in a manner that can reduce a temporary decrease in assist torque associated with the abnormality. .

According to one aspect of the present disclosure, an assist motor that includes a first-system winding and a second-system winding and generates assist torque;
A first-system drive circuit for energizing the first-system winding of the assist motor;
A second drive circuit for energizing the second winding of the assist motor;
A plurality of first energization paths for the windings of the first system via the first system drive circuit, wherein a plurality of first energization paths for generating rotational torque of the assist motor by sequentially switching the energization state. When,
A plurality of second energization paths for the windings of the second system via the drive circuit of the second system, and a plurality of second energization paths that generate rotational torque of the assist motor by sequentially switching the energization state. When,
A control device for controlling the drive circuit of the first system and the drive circuit of the second system,
The control device corresponds to a first energization path that is energized among the plurality of first energization paths among the plurality of second energization paths while sequentially switching energization states of the plurality of first energization paths. An electric power steering device that determines whether or not there is an abnormality in the second energization path by performing energization for abnormality detection in the same direction as the energization direction in the first energization path during energization with respect to the second energization path Is provided.

  According to the present disclosure, it is possible to obtain an electric power steering apparatus that can determine whether or not there is an abnormality in the two windings in a manner that can reduce a temporary decrease in assist torque associated with the abnormality.

1 is an overall view schematically showing an example of a vehicle steering apparatus 10 related to an electric power steering apparatus.
1 is an overall view schematically showing an example of a vehicle steering apparatus 10. FIG. It is a figure which shows an example of the input / output in ECU80. 2 is a diagram illustrating an example of an outline of a power supply system according to an electric power steering device 20. FIG. FIG. 2 is a diagram illustrating an example of a connection mode between a first inverter 71 and a second inverter 72 and the assist motor 22 together with an example of a configuration of the assist motor 22. 4 is a diagram illustrating an example of an energization pattern for the entire winding of the assist motor 22. FIG. FIG. 4 is a diagram illustrating an example of an energization pattern for a first system winding of an assist motor 22. It is a figure which shows an example of the electricity supply pattern with respect to the winding of the 2nd system | strain of the assist motor. 7 is a flowchart illustrating an example of an abnormality detection process executed by a microcomputer 81. It is a figure which shows the equivalent circuit of the 2nd type | system | group winding (U-phase coil U-V2, V-phase coil V-W2, and W-phase coil W-U2) at the time of each electricity supply for abnormality detection.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an overall view schematically showing an example of a vehicle steering apparatus 10. The vehicle steering apparatus 10 includes a steering column 12 including a steering wheel 11 operated by a driver. The steering column 12 rotatably supports a steering shaft 14 that serves as a rotating shaft of the steering wheel 11. The steering shaft 14 is connected to an intermediate shaft (intermediate shaft) 16 via a rubber coupling 13 or the like. The intermediate shaft 16 is connected to a pinion shaft (output shaft), and a pinion 17 of the pinion shaft is engaged with a steering rack (rack bar) 18 in the steering gear box 31. One end of a tie rod 19 is connected to each end of the steering rack 18 and a steered wheel (not shown) is connected to the other end of each tie rod 19 via a knuckle arm or the like (not shown). The intermediate shaft 16 or the steering shaft 14 has a steering angle sensor 26 that generates a signal corresponding to the steering angle of the steering wheel 11 and a torque sensor 15 that generates a signal corresponding to the steering torque applied to the steering shaft 14. Is provided. The torque sensor 15 is provided on each of the intermediate shaft 16 (input shaft) and the pinion shaft (output shaft) coupled by, for example, a torsion bar, and a total of 2 that detects torque based on the rotation angle difference between these shafts. It may be composed of a single resolver sensor.

  The configuration of the vehicle steering device 10 shown in FIG. 1 is merely an example, and the configuration of the vehicle steering device 10 may be arbitrary as long as it includes an electric power steering device 20 described later.

  The vehicle steering apparatus 10 includes an electric power steering apparatus 20. The electric power steering apparatus 20 includes an actuator 22 for assisting steering (hereinafter referred to as “assist motor 22”). The assist motor 22 may be composed of, for example, a three-phase brushless motor. The assist motor 22 may be provided in the steering gear box 31 coaxially with the steering rack 18. For example, the assist motor 22 may be engaged with the steering rack 18 via a ball screw nut. The assist motor 22 assists the movement of the steering rack 18 by its driving force. That is, when the assist motor 22 is operated, the ball screw nut is rotated by the rotation of the rotor, and thereby the steering rack 18 is moved (assisted) in the axial movement. The mechanical configuration itself of the electric power steering apparatus 20 may be arbitrary including the place where the assist motor 22 is disposed. For example, the assist motor 22 may be meshed with a steering shaft (pinion shaft or the like), or may transmit an assisting force via a hydraulic device. The assist motor 22 of the electric power steering device 20 is controlled by an ECU 80 described later. The control mode of the assist motor 22 will be described later.

  FIG. 2 is a diagram illustrating an example of input / output in the ECU 80. The vehicle steering apparatus 10 includes an ECU 80 that performs various controls described below. The ECU 80 is configured by a microcomputer, and includes, for example, a CPU, a ROM that stores a control program, a readable / writable RAM that stores calculation results, a timer, a counter, an input interface, an output interface, and the like.

  The ECU 80 may be realized by a single ECU that controls the steering system, or may be realized in cooperation with two or more ECUs. The ECU 80 receives information or data for realizing various controls described below. For example, various sensor values may be input to the ECU 80 at predetermined intervals from the torque sensor 15, the rotation angle sensor 24, the steering angle sensor 26, a vehicle speed sensor (not shown), and the like. Further, the ECU 80 is connected or built in a current sensor that detects a current flowing through each of the UV, VW, and WU energization paths described later. In addition, the assist motor 22 is connected to the ECU 80 as a control target.

  The ECU 80 determines a target value related to assist torque (assist force) to be generated by the assist motor 22 based on output signals from the torque sensor 15 and the rotation angle sensor 24. The target value related to the assist torque may be any physical quantity including current, voltage, and the like, and may be an assist motor current value (motor drive duty) applied to the assist motor 22, for example. The target value related to the assist torque may be determined in any manner. For example, the target value related to the assist torque may be determined such that the assist torque increases as the steering torque increases by the driver, and may be determined such that the assist torque becomes smaller when the vehicle speed is large than when the vehicle speed is small. The assist motor current value applied to the assist motor 22 may be feedback controlled based on an output signal of the rotation angle sensor 24 that detects the rotation angle of the assist motor 22 (rotor).

  FIG. 3 is a diagram illustrating an example of an outline of a power supply system according to the electric power steering apparatus 20.

  As shown in FIG. 3, a first inverter 71 and a second inverter 72 are connected in parallel to the assist motor 22. The first inverter 71 and the second inverter 72 are examples of a first system drive circuit and a second system drive circuit, respectively. The first inverter 71 and the second inverter 72 are each connected to a power supply voltage (+ B). The power supply voltage may be an in-vehicle battery or an alternator.

  The first inverter 71 may include a three-phase bridge circuit composed of six switching elements S1 to S6. The switching elements S1 to S6 may be arbitrary switching elements such as transistors. The direct current applied to the first inverter 71 is converted into three-phase AC power by a three-phase bridge circuit. The switching elements S1 to S6 of the first inverter 71 are controlled by the microcomputer 81 and the first pre-driver IC 82. Specifically, the microcomputer 81 determines a target value related to the assist torque, and the first pre-driver IC 82 sets a switching pattern corresponding to the target value (switching pattern of duty corresponding to the target value) to the switching elements S1 to S6. Apply to.

  Similarly, the second inverter 72 may include a three-phase bridge circuit including six switching elements S7 to S12. The switching elements S7 to S12 may be arbitrary switching elements such as transistors. The direct current applied to the second inverter 72 is converted into three-phase AC power by a three-phase bridge circuit. The switching elements S7 to S12 of the second inverter 72 are controlled by the microcomputer 81 and the second pre-driver IC 83. Specifically, the microcomputer 81 determines a target value related to the assist torque, and the second pre-driver IC 83 applies a switching pattern corresponding to the target value to the switching elements S7 to S12. Note that the first pre-driver IC 82 and the second pre-driver IC 83 may be integrated.

  In the example illustrated in FIG. 3, the first inverter 71, the second inverter 72, the microcomputer 81, the first predriver IC 82, the second predriver IC 83, and the power supply circuit 84 are components of the ECU 80. However, the ECU 80 may include other components or a part thereof may be provided outside. For example, the first inverter 71 and the second inverter 72 may be provided outside the ECU 80. Further, the ECU 80 may be modularized integrally with the assist motor 22.

  A first switch 73 is provided between the first inverter 71 and the power supply voltage. As shown in FIG. 3, the first switch 73 may be a relay-type switch (mechanical switch), or may be a semiconductor switching element such as a transistor.

  Similarly, a second switch 74 is provided between the second inverter 72 and the power supply voltage. As shown in FIG. 3, the second switch 74 may be a relay type switch (mechanical switch), or may be a semiconductor switching element such as a transistor. The first switch 73 and the second switch 74 are connected in parallel to the power supply voltage corresponding to the first inverter 71 and the second inverter 7. The first switch 73 and the second switch 74 may be omitted.

  Note that a DC-DC converter 90 may be connected as an arbitrary configuration between the first inverter 71 and the second inverter 72 and the power supply voltage. The DC-DC converter 90 boosts the power supply voltage and outputs it to the first inverter 71 and the second inverter 72 side. The DC-DC converter 90 may have any configuration, and may be, for example, a synchronous rectification type non-insulated DC / DC converter.

  Further, open relays 71u, 71v, 71w may be provided between the first inverter 71 and the assist motor 22. Note that the open relays 71u, 71v, 71w may be realized by semiconductor switching elements instead of mechanical relays. The open relays 71u, 71v, 71w are basically kept closed during the operation of the assist motor 22 (exception will be described later). Further, open relays 72u, 72v, 72w may be provided between the second inverter 72 and the assist motor 22. Note that the open relays 72u, 72v, 72w may be realized by semiconductor switching elements instead of mechanical relays. The open relays 72u, 72v, 72w are basically kept closed during the operation of the assist motor 22 (explained later).

  FIG. 4 is a diagram illustrating an example of a configuration of the assist motor 22 and an example of a connection mode between the first inverter 71 and the second inverter 72 and the assist motor 22. In FIG. 4, the power supply circuit 84 and the like are not shown. In FIG. 4, the terminals U1 are electrically connected to each other, the terminals V1 are electrically connected to each other, and the terminals W1 are electrically connected to each other. Similarly, in FIG. 4, each terminal U2 is electrically connected to each other, each terminal V2 is electrically connected to each other, and each terminal W2 is electrically connected to each other.

  As shown in FIG. 4, the assist motor 22 has two windings (double winding configuration). Specifically, the assist motor 22 includes a first series of windings and a second series of windings that are independent of each other. For example, the first series winding and the second winding are wound around the stator of the assist motor 22, respectively. The winding method is arbitrary, and for example, a winding method such as concentrated winding, distributed winding or lap winding may be adopted.

  The first series of windings include a U-phase coil U-V1, a V-phase coil V-W1, and a W-phase coil W-U1 that are energized via first inverter 71. The second series of windings include a U-phase coil U-V2, a V-phase coil V-W2, and a W-phase coil W-U2 that are energized via second inverter 72. In the example shown in FIG. 4, the first series of windings and the second series of windings are each configured by star connection, but may be other configurations such as delta connection. U-phase coil U-V1, V-phase coil V-W1, W-phase coil W-U1, U-phase coil U-V2, V-phase coil V-W2, and W-phase coil W-U2 all have the same characteristics ( For example, an inductance). In the following, U-phase coil U-V1, V-phase coil V-W1, W-phase coil W-U1, U-phase coil U-V2, V-phase coil V-W2, and W-phase coil W-U2 are all the same. The description will be continued on the assumption that the coil has the above characteristics.

  According to the configuration shown in FIG. 4, since the first inverter 71 and the second inverter 72 are connected in parallel to the assist motor 22, only one of the first inverter 71 and the second inverter 72 is operated. Thus, the assist motor 22 can be operated.

  When operating the first inverter 71, when the microcomputer 81 determines the target value related to the assist torque to be generated by the assist motor 22 as described above, the microcomputer 81 turns on the first switch 73 and turns off the second switch 74. A switching pattern corresponding to the target value is applied to the switching elements S1 to S6 via the first pre-driver IC 82. When such a switching pattern is applied to the switching elements S1 to S6, the switching elements S1 to S6 are turned on / off according to the switching pattern, and the U1-V1 energization path (path between the terminal U1 and the terminal V1), the V1-W1 energization path. The energization states of (the path between the terminal V1 and the terminal W1) and the W1-U1 energization path (the path between the terminal W1 and the terminal U1) are sequentially switched.

  When operating the second inverter 72, when the microcomputer 81 determines the target value related to the assist torque to be generated by the assist motor 22 as described above, the microcomputer 81 turns off the first switch 73 and turns on the second switch 74. A switching pattern corresponding to the target value is applied to the switching elements S7 to S12 via the second pre-driver IC 83. When such a switching pattern is applied to the switching elements S7 to S12, the switching elements S7 to S12 are turned on / off according to the switching pattern, and a U2-V2 energization path (a path between the terminal U2 and the terminal V2) and a V2-W2 energization path. The energization states of (the path between the terminal V2 and the terminal W2) and the W2-U2 energization path (the path between the terminal W2 and the terminal U2) are sequentially switched.

  Moreover, according to the structure shown in FIG. 4, both the 1st inverter 71 and the 2nd inverter 72 can also operate | move simultaneously. In this case, the microcomputer 81 turns on the first switch 73 and turns on the second switch 74, determines a target value related to the assist torque, and sets a distribution target value obtained by distributing the target value at a predetermined ratio to the first target value. The pre-driver IC 82 and the second pre-driver IC 83 are provided. For example, when the first inverter 71 and the second inverter 72 are operated at a ratio of 1: 9, a switching pattern corresponding to 10% of the target value is applied to the switching elements S1 to S6 and corresponds to 90% of the target value. A switching pattern is applied to the switching elements S7 to S12. At this time, the current flowing through the U1-V1 energization path, the V1-W1 energization path, and the W1-U1 energization path according to the first inverter 71, and the U2-V2 energization path, the V2-W2 energization path, and W2 according to the second inverter 72. Although the currents flowing through the -U2 energization path flow independently of each other, they cooperate to form a rotating magnetic field. As a result, energization is performed to achieve 100% of the target value as a whole.

  The first inverter 71 and the second inverter 72 preferably have the same rating, and have the ability to independently generate the maximum value of assist torque (the maximum value intended by design). That is, both the first inverter 71 and the second inverter 72 can generate the maximum value of the assist torque when operating alone. The maximum value of the assist torque corresponds to the maximum value that can be taken by the target value related to the assist torque. Hereinafter, the description will be continued on the assumption that the first inverter 71 and the second inverter 72 have the same rating and have the ability to independently generate the maximum value of the assist torque.

  FIG. 5 is a diagram illustrating an example of energization patterns for the U-phase coil, the V-phase coil, and the W-phase coil of the assist motor 22. Here, the U-phase coil refers to the whole (total) of the U-phase coil U-V1 and the U-phase coil U-V2, and the same applies to the V-phase coil and the W-phase coil.

  In the example shown in FIG. 5, the energization pattern of the U-phase coil is shown in a mechanical angle range of 0 to 360 degrees, 120 degrees positive direction energization, 60 degrees non-energization, and 120 degrees negative direction energization. , Consisting of 60 degree de-energization. The same applies to the energization patterns of the V-phase coil and the W-phase coil. However, the energization patterns of the U-phase coil, V-phase coil, and W-phase coil are shifted by 120 degrees with respect to each other.

  In FIG. 5, energization in the direction from the U-phase terminal to the V-phase terminal is realized in the period t1, and in the period t2, energization in the direction from the U-phase terminal to the W-phase terminal is realized. Energization in the direction from the phase terminal to the W-phase terminal is realized, energization in the direction from the V-phase terminal to the U-phase terminal is realized in the period t4, and energization in the direction from the W-phase terminal to the U-phase terminal is realized in the period t5. In the period t6, energization in the direction from the W-phase terminal to the V-phase terminal is realized.

  FIG. 6 is a diagram illustrating an example of an energization pattern for the first system windings of the assist motor 22 (U-phase coil U-V1, V-phase coil V-W1, and W-phase coil W-U1). FIG. 7 is a diagram illustrating an example of an energization pattern for the second system winding (the U-phase coil U-V2, the V-phase coil V-W2, and the W-phase coil W-U2) of the assist motor 22. Note that when the energization pattern for the first system winding and the energization pattern for the second system winding are added together, the energization pattern (total energization pattern) shown in FIG. 5 is obtained. The energization patterns shown in FIGS. 6 and 7 are shown in a mechanical angle range of 0 to 360 degrees, and the same pattern is periodically generated every mechanical angle 360 degrees.

  The energization pattern for the first system winding of the assist motor 22 and the energization pattern for the second system winding of the assist motor 22 occur alternately as shown in FIGS. 6 and 7. In the example shown in FIGS. 6 and 7, the winding of the first system is responsible for the mechanical angle range of the rotor of the assist motor 22, and the winding of the second system is the machine of the rotor of the assist motor 22. It is responsible for a range of 180-360 degrees.

  More specifically, with respect to the energization pattern for the first-system winding, energization in the direction from the U-phase terminal (U1) to the V-phase terminal (V1) is realized in the period t1, and the U-phase terminal in the period t2. Energization in the direction from the (U1) to the W-phase terminal (W1) is realized, and in the period t3, energization in the direction from the V-phase terminal (V1) to the W-phase terminal (W1) is realized, and in the period t4, the V-phase terminal Energization in the direction from the (V1) to the U-phase terminal (U1) is realized, and in the period t5, energization in the direction from the W-phase terminal (W1) to the U-phase terminal (U1) is realized, and in the period t6, the W-phase terminal Energization in the direction from the (W1) to the V-phase terminal (V1) is realized. The energization pattern for the windings of the first system in the periods t1 to t6 is an energization pattern that realizes 100% of the target value (target value related to assist torque to be generated by the assist motor 22). From period t7 to t12, energization is not performed for the windings of the first system. However, at the time of abnormality detection, as will be described later, very little energization is performed for abnormality detection.

  About the energization pattern with respect to the winding of the 2nd system, energization is not performed to the winding of the 2nd system until the period t1-t6. However, at the time of abnormality detection, as will be described later, very little energization is performed for abnormality detection. In the period t7, energization in the direction from the U phase terminal (U2) to the V phase terminal (V2) is realized, and in the period t8, energization in the direction from the U phase terminal (U2) to the W phase terminal (W2) is realized. In the period t9, energization in the direction from the V-phase terminal (V2) to the W-phase terminal (W2) is realized, and in period t10, energization in the direction from the V-phase terminal (V2) to the U-phase terminal (U2) is realized. In the period t11, energization in the direction from the W-phase terminal (W2) to the U-phase terminal (U2) is realized, and in period t12, energization in the direction from the W-phase terminal (W2) to the V-phase terminal (V2) is realized. . The energization pattern for the windings of the first system in the period t7 to t12 is an energization pattern that realizes 100% of the target value (target value related to assist torque to be generated by the assist motor 22).

  In the example shown in FIGS. 6 and 7, the switching period of energization for the first system winding and the second system winding of the assist motor 22 is every 180 degrees in mechanical angle, but the switching period is It is not limited to 180 degrees and is arbitrary. The switching cycle may be dynamically changed. Further, the energization time for the first system winding and the energization time for the second system winding need not be the same periodically, and switching may be realized in such a manner that one is energized longer than the other. .

  FIG. 8 is a flowchart illustrating an example of an abnormality detection process executed by the microcomputer 81. The processing routine shown in FIG. 8 may be periodically executed while the target value related to the assist torque is larger than zero, for example. For example, the processing routine shown in FIG. 8 may be executed every energization period (for example, the period from t1 to t6 in FIG. 6) for the windings of the first system. Hereinafter, an example of the abnormality detection process for the winding of the first system will be described, but the same may be applied to the abnormality detection process for the winding of the second system (relationship between the first system and the second system). Is just the opposite). In this case, similarly, the abnormality detection process for the winding of the first system may be executed every energization period (for example, the period from t7 to t12 in FIG. 6) for the winding of the second system.

  In step 800, it is determined whether or not energization in the direction from the U-phase terminal (U1) to the V-phase terminal (V1) (energization to the U1-V1 energization path) is being performed on the first-system winding. . For example, in the example shown in FIG. 6, it is determined whether or not it is within the period t1. If the U1-V1 energization path is being energized, the process proceeds to step 802. Otherwise, the U1-V1 energization path is waited for energization.

  In step 802, as the abnormality detection energization, the energization in the direction from the U-phase terminal (U2) to the V-phase terminal (V2) (energization to the U2-V2 energization path) is performed on the windings of the second system. The abnormality detection energization may be a minimum energization necessary for the abnormality detection. For example, the abnormality detection energization pattern is equal to or less than 30% of the target value (target value related to assist torque to be generated by the assist motor 22), more preferably equal to or less than 20% of the target value, and most preferably 10% of the target value. The energization pattern is such that a considerable amount is realized. This is because the assist torque is generated even when the abnormality detection energization is performed, so that an unintended increase (variation) of the assist torque due to the generation of the assist torque is prevented. However, in anticipation of an increase in assist torque due to such abnormality detection energization, the energization pattern in the direction from the U-phase terminal (U1) to the V-phase terminal (V1) for the windings of the first system is less than 100% of the target value. It may be corrected to such an energization pattern. At this time, the energization pattern in the direction from the U-phase terminal (U1) to the V-phase terminal (V1) with respect to the winding of the first system is such that 100% of the target value is realized in the entire first system and second system. The energization pattern may be corrected.

  During energization for anomaly detection in the U2-V2 energization path, preferably open to prevent current flow to or from the second inverter 72 through the W-phase terminal (W2). The relay 72w (see FIG. 4) is opened.

  In step 803, the presence / absence of abnormality in the winding of the second system is determined based on the current sensor value obtained when the abnormality detection energization in step 802 is performed. In addition, the abnormality here is mainly the disconnection of the 2nd winding (U-phase coil U-V2, V-phase coil V-W2, and W-phase coil W-U2). The disconnection of the second winding may occur independently in the U-phase coil U-V2, the V-phase coil V-W2, and the W-phase coil W-U2. An abnormality determination method based on the current sensor value is arbitrary, but an example will be described later.

  In step 804, it is determined whether or not energization in the direction from the V-phase terminal (V1) to the W-phase terminal (W1) (energization to the V1-W1 energization path) is being performed on the first-system winding. . For example, in the example shown in FIG. 6, it is determined whether or not it is within the period t3. If the V1-W1 energization path is being energized, the process proceeds to step 806. Otherwise, the process waits for energization of the V1-W1 energization path.

  In step 806, as abnormality detection energization, energization in the direction from the V-phase terminal (V2) to the W-phase terminal (W2) (energization to the V2-W2 energization path) is performed on the windings of the second system. Similarly, the abnormality detection energization to the V2-W2 energization path may be the minimum energization necessary for the abnormality detection. Similarly, during the energization for detecting an abnormality in the V2-W2 energization path, it is preferable to prevent a current flow to or from the second inverter 72 via the U-phase terminal (U2). In order to do this, the open relay 72u (see FIG. 4) is opened.

  In step 807, the presence / absence of abnormality in the winding of the second system is determined based on the current sensor value obtained during the abnormality detection energization in step 806. An abnormality determination method based on the current sensor value is arbitrary, but an example will be described later.

  In step 808, it is determined whether or not energization in the direction from the W-phase terminal (W1) to the U-phase terminal (U1) (energization to the W1-U1 energization path) is being performed on the first-system winding. . For example, in the example shown in FIG. 6, it is determined whether or not it is within the period t5. If the W1-U1 energization path is energized, the process proceeds to step 810. Otherwise, the W1-U1 energization path is waited for energization.

  In step 810, energization in the direction from the W-phase terminal (W2) to the U-phase terminal (U2) (energization to the W2-U2 energization path) is performed on the second-system winding as abnormality detection energization. Similarly, the abnormality detection energization to the W2-U2 energization path may be the minimum energization necessary for the abnormality detection. Similarly, during the energization for abnormality detection in the W2-U2 energization path, preferably to prevent the flow of current to or from the second inverter 72 via the V-phase terminal (V2). In addition, the open relay 72v (see FIG. 4) is opened.

  In step 812, the presence / absence of abnormality in the winding of the second system is determined based on the current sensor value obtained when the abnormality detection energization in step 810 is performed. An abnormality determination method based on the current sensor value is arbitrary, but an example will be described later.

  As a result of the processing shown in FIG. 8, an abnormality is detected in at least one of the second windings (U-phase coil U-V2, V-phase coil V-W2, and W-phase coil W-U2). In such a case, the energization state for the windings of the first system may be maintained. That is, switching from energization of the first system winding to energization of the second system winding may not be performed, and energization of the first system winding may be continued. For example, in the example shown in FIGS. 6 and 7, the energization pattern similar to that from the period t1 to the period t6 may be applied to the first system windings from the period t7 to the period t12. Thereby, the temporary fall of the assist torque which may arise at the time of energization switching to the winding of the 2nd system with an abnormality can be reduced.

  Next, an example of an abnormality determination method that may be used in the processing of Step 803, Step 807, and Step 812 in FIG. 8 will be described. Here, a current sensor that detects a current flowing through the U2-V2 energization path, a current sensor that detects a current flowing through the V2-W2 energization path, and a current sensor that detects a current flowing through the W2-U2 energization path are used. An example of the abnormality determination method will be described. Note that these current sensors may be incorporated in the second inverter 72. Similarly, an example of an abnormality determination method for the first system winding will be described below, but the same may be applied to the abnormality determination method for the second system winding.

  FIG. 9A shows an equivalent circuit of the second-system winding (the U-phase coil U-V2, the V-phase coil V-W2, and the W-phase coil W-U2) when the abnormality detection energization in step 802 is performed. FIG. 9B shows an equivalent circuit of the winding of the second system when the abnormality detection energization is performed in step 806, and FIG. 9C shows the second circuit when the abnormality detection energization is performed in step 810. The equivalent circuit of a system winding is shown.

At the time of abnormality detection energization in step 802, that is, energization from the U-phase terminal (U2) to the V-phase terminal (V2) (energization to the U2-V2 energization path), the equivalent shown in FIG. A circuit is formed. When the winding of the second system is normal (when there is no disconnection in any of the U-phase coil U-V2, V-phase coil V-W2 and W-phase coil W-U2), the current is the U-phase terminal (U2) To the V-phase terminal (V2) through the U-phase coil U-V2, and the V-phase coil V-W2 and the W-phase connected in series from the U-phase terminal (U2) to the V-phase terminal (V2). It flows through the coil W-U2. At this time, the combined resistance Ru-v between the U-phase terminal (U2) and the V-phase terminal (V2) is as follows.
Ru−v = (R1 + R2 + R3) / {R1 × (R2 + R3)} Formula (1)
Here, R1, R2, and R3 represent resistance line segments of the U-phase coil U-V2, the V-phase coil V-W2, and the W-phase coil W-U2, respectively.
On the other hand, when the U-phase coil U-V2 is disconnected, current does not flow from the U-phase terminal (U2) to the V-phase terminal (V2) via the U-phase coil U-V2, and the U-phase terminal ( It flows only from U2) to V-phase terminal (V2) via V-phase coil V-W2 and W-phase coil W-U2 connected in series. Therefore, the combined resistance Ru-v at this time is as follows.
Ru-v = R2 + R3 Formula (2)
On the other hand, when there is no abnormality in the U-phase coil U-V2 and the V-phase coil V-W2 and / or the W-phase coil W-U2 is disconnected, the current is supplied from the U-phase terminal (U2) to the V-phase terminal ( V2) does not flow through the V-phase coil V-W2 and W-phase coil W-U2 connected in series, and the U-phase coil U-V2 is connected from the U-phase terminal (U2) to the V-phase terminal (V2). Flows only through. Therefore, the combined resistance Ru-v at this time is as follows.
Ru-v = R1 Formula (3)
Therefore, in step 803, the voltage Vu-v (control value or detection value) between the U-phase terminal (U2) and the V-phase terminal (V2) and the current sensor that detects the current flowing through the U2-V2 energization path are displayed. Based on the sensor value Iu-v, the combined resistance Ru-v (= Vu-v / Iu-v) is calculated, and the calculated combined resistance Ru-v is calculated by the formulas (1), (2), and ( It suffices to check which combined resistance Ru-v of 3) corresponds. When it corresponds to Formula (1), it can be determined that none of the U-phase coil U-V2, the V-phase coil V-W2, and the W-phase coil W-U2 is disconnected, that is, normal. In this case, the processing after step 804 in FIG. 8 may be omitted. When the calculated combined resistance Ru-v corresponds to the equation (2), there is no abnormality in the V-phase coil V-W2 and the W-phase coil W-U2, and there is an abnormality (disconnection) in the U-phase coil U-V2. Judgment can be made. Also in this case, the processing after step 804 in FIG. 8 may be omitted. On the other hand, when the calculated combined resistance Ru-v corresponds to Equation (3), there is no abnormality in the U-phase coil U-V2, and there is an abnormality (disconnection) in the V-phase coil V-W2 and / or the W-phase coil W-U2. ). Which of the V-phase coil V-W2 and the W-phase coil W-U2 is disconnected is determined by the subsequent processing in step 807 and the like as described below. However, if it is not necessary to specify which coil has an abnormality, the processing after step 804 in FIG. 8 may be omitted.

  At the time of abnormality detection energization in step 806, that is, energization from the V-phase terminal (V2) to the W-phase terminal (W2) (energization through the V2-W2 energization path), the equivalent shown in FIG. A circuit is formed. When the winding of the second system is normal (when there is no disconnection in any of the U-phase coil U-V2, V-phase coil V-W2 and W-phase coil W-U2), the current is the V-phase terminal (V2). From the V-phase terminal V2 to the W-phase terminal (W2), the U-phase coil U-V2 and the W-phase are connected in series from the V-phase terminal V2 to the W-phase terminal W2. It flows through the coil W-U2.

When the V-phase coil V-W2 is disconnected, current does not flow from the V-phase terminal (V2) to the W-phase terminal (W2) via the V-phase coil V-W2, but the V-phase terminal (V2). To the W-phase terminal (W2) through only the U-phase coil U-V2 and the W-phase coil W-U2 connected in series. At this time, the combined resistance Rv-w between the V-phase terminal (V2) and the W-phase terminal (W2) is as follows.
Rv−w = R1 + R3 Formula (4)
However, when the disconnection of the U-phase coil U-V2 is already known, no current flows.
On the other hand, when there is no abnormality in the V-phase coil V-W2 and the U-phase coil U-V2 and / or the W-phase coil W-U2 is disconnected, the current is supplied from the V-phase terminal (V2) to the W-phase terminal ( W2) does not flow through U-phase coil U-V2 and W-phase coil W-U2 connected in series, and V-phase coil V-W2 is connected from V-phase terminal (V2) to W-phase terminal (W2). Flows only through. Accordingly, the combined resistance Rv-w at this time is as follows.
Rv−w = R2 Formula (5)
Therefore, in the above step 807, the voltage Vv-w (control value or detection value) between the V-phase terminal (V2) and the W-phase terminal (W2) and the current sensor that detects the current flowing through the V2-W2 energization path. Based on the sensor value Iv-w, the combined resistance Rv-w (= Vv-w / Iv-w) is calculated, and the calculated combined resistance Rv-w is any of the expressions (4) and (5). What is necessary is just to check whether it corresponds to synthetic | combination resistance Rv-w. When it corresponds to Formula (4), it can be judged that there is no abnormality in the U-phase coil U-V2 and the W-phase coil W-U2, and there is an abnormality (disconnection) in the V-phase coil V-W2. Also in this case, the processing after step 808 in FIG. 8 may be omitted. On the other hand, when the calculated combined resistance Rv-w corresponds to the equation (5), there is no abnormality in the V-phase coil V-W2, and there is an abnormality (disconnection in the U-phase coil U-V2 and / or the W-phase coil W-U2). ). In this case, when it is determined in step 803 that there is no abnormality in the U-phase coil U-V2, it can be determined that there is an abnormality (disconnection) in the W-phase coil W-U2. When it is determined in step 803 that there is an abnormality in the U-phase coil U-V2, the processes after step 808 in FIG. 8 are executed in order to determine whether the W-phase coil W-U2 is abnormal. Good. Further, when no current flows through the V2-W2 energization path when energizing the V2-W2 energization path (when there is an abnormality in the U-phase coil U-V2 and the V-phase coil V-W2), the W-phase coil W In order to determine whether there is an abnormality in -U2, the processing after step 808 in FIG. 8 may be executed.

  At the time of abnormality detection energization in step 810, that is, energization from the W-phase terminal (W2) to the U-phase terminal (U2) (energization to the W2-U2 energization path), the equivalent shown in FIG. A circuit is formed. When the winding of the second system is normal (when there is no disconnection in any of the U-phase coil U-V2, the V-phase coil V-W2, and the W-phase coil W-U2), the current is the W-phase terminal (W2). The U-phase coil U-V2 and the V-phase are connected in series from the W-phase terminal (U2) to the U-phase terminal (U2) through the W-phase coil W-U2 and from the W-phase terminal (W2) to the U-phase terminal (U2). It flows through the coil V-W2.

When the W-phase coil W-U2 is disconnected, current does not flow from the W-phase terminal (W2) to the U-phase terminal (U2) via the W-phase coil W-U2, but the W-phase terminal (W2). To the U-phase terminal (U2) only through the U-phase coil U-V2 and the V-phase coil V-W2 connected in series. At this time, the combined resistance Rw-u between the W-phase terminal (W2) and the U-phase terminal (U2) is as follows.
Rw−u = R1 + R2 Formula (6)
However, when the disconnection of the U-phase coil U-V2 and / or the V-phase coil V-W2 is already known, no current flows.
On the other hand, when there is no abnormality in the W-phase coil W-U2 and the U-phase coil U-V2 and / or the V-phase coil V-W2 is disconnected, the current is supplied from the W-phase terminal (W2) to the U-phase terminal ( U2) does not flow through the U-phase coil U-V2 and V-phase coil V-W2 connected in series, and the W-phase coil W-U2 is connected from the W-phase terminal (W2) to the U-phase terminal (U2). Flows only through. Therefore, the combined resistance Rw-u at this time is as follows.
Rw−u = R3 Formula (7)
Accordingly, in step 812, the voltage Vw-u (control value or detection value) between the W-phase terminal (W2) and the U-phase terminal (U2) and the current sensor that detects the current flowing through the W2-U2 energization path are displayed. Based on the sensor value Iw-u, a combined resistance Rw-u (= Vw-u / Iw-u) is calculated, and the calculated combined resistance Rw-u is determined by any one of the expressions (6) and (7). It may be checked whether it corresponds to the combined resistance Rw-u. When it corresponds to the equation (6), it can be determined that there is no abnormality in the U-phase coil U-V2 and the V-phase coil V-W2, and there is an abnormality (disconnection) in the W-phase coil W-U2. Moreover, when corresponding to Formula (7), it can be determined that there is no abnormality in the W-phase coil W-U2.

  As described above, according to the processing shown in FIG. 8, the abnormality detection energization is performed on the second system winding while the assist motor 22 is energized on the first system winding, whereby the second system winding. The presence / absence of an abnormality in the wire can be determined while assist torque is generated by energization of the first system winding of the assist motor 22. Thereby, when abnormality of the winding of the second system is detected, by energizing the winding of the first system (by not switching the energization to the winding of the second system) Further, it is possible to reduce the temporary decrease of the assist torque due to the abnormality of the second system winding.

  By the way, if the voltages (Vu−v, Vv−w, Vw−u) at the time of energization for detecting an abnormality are too small, the influence of noise becomes relatively large, and the reliability of the calculated value of the combined resistance R described above is high. It becomes worse and the abnormality determination accuracy becomes worse. On the other hand, when the voltage at the time of energization for abnormality detection is too large, the influence on the assist torque of the assist motor 22 becomes large. For example, when the abnormality detection energization is performed with an energization pattern in which 50% of the target value (target value related to the assist torque to be generated by the assist motor 22) is realized, 150% of the target value is realized at the time of abnormality detection energization. As a result, the assist torque increases rapidly. On the other hand, in order to prevent such a sudden increase, when the abnormality detection energization is performed with an energization pattern that achieves 50% of the target value, the energization pattern for the windings of the first system is realized to be 50% of the target value. It is also possible to correct the energization pattern. However, in such a configuration, if there is an abnormality in the winding of the second system, the energization pattern for the winding of the first system is 50% of the target value until the energization pattern is restored to 100% of the target value. However, the assist torque is temporarily reduced.

  In this regard, according to the process shown in FIG. 8, the abnormality detection energization is the minimum energization necessary for the abnormality detection with respect to the windings of the second system. Here, the minimum energization necessary for abnormality detection may be adapted from the balance between the abnormality determination accuracy and the influence of the assist motor 22 on the assist torque. For example, as described above, the abnormality detection energization pattern is equal to or less than 30% of the target value (target value related to assist torque to be generated by the assist motor 22), more preferably equal to or less than 20% of the target value, and most preferably the target. The energization pattern is such that 10% or less of the value is realized. As a result, it is possible to detect the abnormality in the windings of the second system, and to reduce the variation in the assist torque of the assist motor 22 that accompanies the occurrence of abnormality or that accompanies power supply for abnormality detection.

  Moreover, according to the process shown in FIG. 8, only the predetermined open relay of the open relays 72u, 72v, and 72w is opened at the time of abnormality detection energization. For example, when the U2-V2 energization path is energized, the open relay 72w related to the W phase is opened. As a result, no current flows from the second inverter 72 or through the W-phase terminal (W2) to the second inverter 72 when the abnormality detection energization is applied to the U2-V2 energization path, so the combined resistance Ru-v Can be improved, and the abnormality determination accuracy can be increased. Similarly, when the V2-W2 energization path is energized, the open relay 72u related to the U phase is opened, so that the calculation accuracy of the combined resistance Rv-w can be increased and the abnormality determination accuracy can be increased. . Similarly, when the W2-U2 energization path is energized, the open relay 72v related to the V phase is opened, so that the calculation accuracy of the combined resistance Rw-u can be increased, and the abnormality determination accuracy can be increased. it can.

  In the process shown in FIG. 8, as an example, abnormality detection energization includes energization in the direction from the U-phase terminal (U2) to the V-phase terminal (V2) (energization to the U2-V2 energization path), and the V-phase terminal (V1). ) In the direction of the W-phase terminal (W1) (energization in the V1-W1 energization path), and energization in the direction of the U-phase terminal (U2) from the W-phase terminal (W2) to the windings of the second system ( The energization of the W2-U2 energization path) is executed in this order, but the execution order may be arbitrary.

  Further, in the process shown in FIG. 8, for example, the abnormality detection energization includes energization in the direction from the U-phase terminal (U2) to the V-phase terminal (V2) (energization to the U2-V2 energization path), V-phase terminal (V1). ) In the direction of the W-phase terminal (W1) (energization in the V1-W1 energization path), and energization in the direction of the U-phase terminal (U2) from the W-phase terminal (W2) to the windings of the second system ( This is realized by energization of the W2-U2 energization path), but the abnormality can be detected by energization in the other direction. For example, during energization in the direction from the V-phase terminal (V1) to the U-phase terminal (U1) (energization to the U1-V1 energization path) is being performed on the winding of the first system (see period t4 in FIG. 6). The energization in the direction from the V-phase terminal (V2) to the U-phase terminal (U2) (energization to the U2-V2 energization path) may be executed as the abnormality detection energization for the windings of the second system. In addition, while energization in the direction from the W-phase terminal (W1) to the V-phase terminal (V1) (energization to the V1-W1 energization path) is being performed on the winding of the first system (see period t6 in FIG. 6), Energization in the direction from the W-phase terminal (W2) to the V-phase terminal (V2) (energization to the V2-W2 energization path) may be executed as the abnormality detection energization for the windings of the second system. In addition, while energization in the direction from the U-phase terminal (U1) to the W-phase terminal (W1) (energization to the W1-U1 energization path) is being performed on the winding of the first system (see period t2 in FIG. 6), Energization in the direction from the U-phase terminal (U2) to the W-phase terminal (W2) (energization to the W2-U2 energization path) may be performed as abnormality detection energization for the second-system winding.

  Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes can be made within the scope described in the claims. It is also possible to combine all or a plurality of the components of the above-described embodiments.

  For example, in the examples shown in FIGS. 5 to 7, a rectangular waveform energization pattern is simply shown, but the phase currents of the U-phase coil, V-phase coil, and W-phase coil of the assist motor 22 are 120 to each other. An energization pattern that has a sinusoidal waveform with a phase difference may be used.

  Moreover, although the patterns shown in FIGS. 5 to 7 have been described as energization patterns, they can also be considered as switching patterns applied to the switching elements S1 to S6 and the switching elements S7 to S12. In this case, the plus-side pulse waveform may be considered as an on signal of the upper arm switching element, and the minus side pulse waveform may be considered as an on signal of the lower arm switching element. At this time, the height (amplitude) of the pulse waveform may be considered to represent a ratio to the duty at which 100% of the target value is realized.

  In the embodiment described above, a current sensor that detects the current in the U2-V2 energization path, a current sensor that detects the current in the V2-W2 energization path, and a current sensor that detects the current in the W2-U2 energization path are used. However, instead of these, a current sensor for detecting a current flowing through the winding of each phase of the second system (U-phase coil U-V2, V-phase coil V-W2 and W-phase coil W-U2) is provided. May be used.

  In the above-described embodiment, the assist motor 22 is a three-phase motor, but may be a motor other than the three-phase motor.

  Further, in the above-described embodiment, the energization pattern for the first system winding of the assist motor 22 and the energization pattern for the second system winding of the assist motor 22 are mutually different, as shown in FIGS. It occurs alternately without overlapping. However, the energization pattern for the first system winding of the assist motor 22 and the energization pattern for the second system winding of the assist motor 22 may alternately occur while overlapping each other. In this case, it is also possible to detect abnormality using the overlap period.

DESCRIPTION OF SYMBOLS 10 Vehicle steering device 11 Steering wheel 12 Steering column 13 Rubber coupling 14 Steering shaft 15 Torque sensor 16 Intermediate shaft 17 Pinion 18 Steering rack 19 Tie rod 20 Electric power steering device 22 Assist motor 24 Rotation angle sensor 26 Steering angle sensor 71 1st Inverter 72 Second inverter 73 First switch 74 Second switch 80 ECU
81 Microcomputer 90 DC-DC converter

Claims (4)

An assist motor having a first system winding and a second system winding and generating assist torque;
A first-system drive circuit for energizing the first-system winding of the assist motor;
A second drive circuit for energizing the second winding of the assist motor;
A plurality of first energization paths for the windings of the first system via the first system drive circuit, wherein a plurality of first energization paths for generating rotational torque of the assist motor by sequentially switching the energization state. When,
A plurality of second energization paths for the windings of the second system via the drive circuit of the second system, and a plurality of second energization paths that generate rotational torque of the assist motor by sequentially switching the energization state. When,
A control device for controlling the drive circuit of the first system and the drive circuit of the second system,
The control device corresponds to a first energization path that is energized among the plurality of first energization paths among the plurality of second energization paths while sequentially switching energization states of the plurality of first energization paths. An electric power steering device that determines whether or not there is an abnormality in the second energization path by performing energization for abnormality detection in the same direction as the energization direction in the first energization path during energization with respect to the second energization path . The assist motor is a three-phase motor, and the windings of the first system and the second system are respectively three-phase windings,
The first system drive circuit includes a first inverter;
The second system drive circuit includes a second inverter;
The plurality of first energization paths include a U-V energization path, a V-W energization path, and a W-U energization path formed between the U-phase, V-phase, and W-phase terminals of the assist motor,
The plurality of second energization paths include a U-V energization path, a V-W energization path, and a W-U energization path formed between the U-phase, V-phase, and W-phase terminals of the assist motor,
The control device energizes the abnormality detection power to the U-V energization path related to the winding of the second system during energization of the U-V energization path related to the winding of the first system, During the energization of the VW energization path related to the winding of the first system, the abnormality detection energization is performed to the VW energization path related to the winding of the second system, and the first system during energization of W-U current path of the windings to energize for the abnormality detection against W-U current path according to the winding of the second system, the electric power steering apparatus according to claim 1 . Between the second-system drive circuit and the U-phase, V-phase, and W-phase terminals of the second system, U-phase, V-phase, and W-phase open switches are respectively included.
When the control device energizes the abnormality detection power to the U-V energization path related to the winding of the second system during energization of the U-V energization path related to the winding of the first system Opens a W-phase opening switch among the plurality of opening switches,
During energization of the VW energization path related to the winding of the second system during energization of the VW energization path related to the winding of the first system, Open the U-phase release switch among the release switches,
During energization of the W-U energization path related to the winding of the second system during energization of the W-U energization path related to the winding of the first system, The electric power steering apparatus according to claim 2, wherein the V-phase opening switch among the opening switches is opened.   The said control apparatus performs electricity supply for the said abnormality detection, operating the said 1st drive circuit so that electricity supply corresponding to 100% of the target value regarding assist torque is implement | achieved. The electric power steering device according to any one of the above.

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