JP6380268B2 - Electric motor control device - Google Patents

Description

  The present invention relates to an electric motor control device.

  2. Description of the Related Art Conventionally, a double redundant configuration electric motor including two windings is known (for example, Patent Document 1). The electric motor (three-phase AC motor) described in Patent Document 1 has the other three-phase winding even when one of the two sets of three-phase windings is abnormal and cannot be energized. The rated output can be output by using.

JP 2003-102189 A

  By the way, an open relay may be provided between a drive circuit (an inverter or the like) that drives the electric motor and the electric motor. For example, when the energization stop to the electric motor becomes impossible due to the abnormality of the drive circuit, the energization to the electric motor can be stopped by opening the open relay (fail-safe function).

  Since such an open relay is normally closed, there is a possibility that an ON failure occurs (a failure that does not return to OFF even if a command to turn OFF is issued), and such a fail-safe function may not be achieved. is there. Therefore, it is desirable to appropriately determine whether there is an abnormality due to an ON failure of the open relay. Specifically, the drive circuit is operated so that a current flows through the open relay in a state after outputting a command to switch the open relay to OFF. If no current flows through the path including the open relay, it can be confirmed that the open relay is normally open (turned off). If the current flows, the open relay has failed. It can be determined that there is an abnormality. In particular, by using the electric motor having the double redundant configuration described in Patent Document 1, the normal operation is performed using one of the two windings, while the other winding is connected to the drive circuit. It is possible to determine the ON failure of the open relay provided in.

  However, when the failure of the open relay provided between the other winding and the drive circuit is determined during the normal operation using one of the windings, the open relay has an ON failure. In addition, current may flow through the other winding. Therefore, there is a possibility that the operation of the electric motor by one winding may be influenced by the influence of the current flowing through the other winding.

  Therefore, in view of the above problems, an electric motor control capable of determining ON failure of an open relay provided between the drive circuit of the electric motor and the winding of the electric motor while suppressing the influence on the operation of the electric motor. An object is to provide an apparatus.

In order to achieve the above object, in one embodiment, an electric motor control device comprises:
An electric motor including two windings;
A drive circuit for energizing one of the two windings;
A relay provided between the one winding and the drive circuit;
A relay control unit for controlling the open / close state of the relay;
A drive control unit for controlling the operation of the drive circuit;
An abnormality determination unit that determines whether or not the relay has an ON failure, and when one of the windings is energized through the relay in a state in which an open command is output from the relay control unit to the relay An abnormality determination unit that determines that the relay has an ON failure,
The drive control unit is configured such that when the abnormality determination unit determines whether or not the relay has an ON failure, the first current that is defined in advance in the one winding flows through the relay. In addition to controlling the drive circuit, when the abnormality determination unit determines that the relay is in an ON failure, the second current in the direction opposite to the first current flows through the one coil through the relay. , Controlling the driving circuit.

  According to the present embodiment, an electric motor capable of determining ON failure of an open relay provided between the drive circuit of the electric motor and the winding of the electric motor while suppressing the influence on the operation of the electric motor. A control device can be provided.

It is a lineblock diagram showing roughly an example of a vehicle steering device relevant to an electric power steering device concerning this embodiment. It is a figure which shows an example of the input / output in ECU. It is a figure which shows an example of the outline | summary of the electric power supply system which concerns on an electric power steering apparatus. 2 is a diagram illustrating an example of a configuration of an assist motor and an example of a connection mode between a first inverter 71 and a second inverter 72 and the assist motor 22. FIG. It is a figure explaining the method of determining the presence or absence of ON failure. It is a figure showing an example of the aspect of the electric current which flows into an assist motor when it determines with the ON failure having generate | occur | produced. It is a timing chart which shows an example of operation of an electric power steering device at the time of judging the existence of ON failure.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram schematically illustrating 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 device 20 includes a steering assist actuator 22 (hereinafter referred to as an 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 direction. 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 or the like, and includes, for example, a CPU, a ROM storing a control program, a readable / writable RAM storing operation 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. Further, the target value related to the assist torque may be determined in an arbitrary 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. Each of the first inverter 71 and the second inverter 72 is an example of a drive circuit for driving one of two windings (see FIG. 4) included in the assist motor 22. 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 changes the switching pattern corresponding to the target value (the switching pattern of the 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 shown 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 constituent elements of the ECU 80. Is not limited. That is, the ECU 80 may include other components, or some components 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 to the power supply voltage in parallel corresponding to the first inverter 71 and the second inverter 72.

  The open / close state of the first switch 73 and the second switch 74 is controlled by the microcomputer 81. The first switch 73 and the second switch 74 may be omitted. Further, 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 configuration of the DC-DC converter 90 may be arbitrary, 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. The open relays 71u, 71v, 71w are opened in response to an open command output from the microcomputer 81 when the energization stop to the assist motor 22 becomes impossible due to a failure of the switching elements S1 to S6. . In addition, open relays 72u, 72v, 72w are provided between the second inverter 72 and the assist motor 22. The open relays 72u, 72v, 72w are opened in response to an open command output from the microcomputer 81 when the energization stop to the assist motor 22 becomes impossible due to a failure of the switching elements S7 to S12 or the like. .

  The open relays 71u, 71v, 71w, 72u, 72v, 72w may be mechanical relays or semiconductor relays.

  FIG. 4 is a diagram illustrating an example of the 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 system winding and a second system winding that are independent of each other. For example, the first system winding and the second system winding are respectively wound around the stator of the assist motor 22. The winding method is arbitrary, and for example, a winding method such as concentrated winding, distributed winding or lap winding may be adopted.

  The winding of the first system includes a U-phase coil U-V-1, a V-phase coil V-W-1, and a W-phase coil W-U-1 that are energized via the first inverter 71. The winding of the second system includes a U-phase coil U-V-2 that is energized via the second inverter 72, a V-phase coil V-W-2, and a W-phase coil W-U-2.

  In the example shown in FIG. 4, the first system winding and the second system winding are each configured by star connection, but may be other configurations such as delta connection. U-phase coil U-V-1, V-phase coil V-W-1, W-phase coil W-U-1, U-phase coil U-V-2, V-phase coil V-W-2, W The phase coils W-U-2 may all be formed from coils having the same characteristics (for example, inductance). In the following, U-phase coil U-V-1, V-phase coil V-W-1, W-phase coil W-U-1, U-phase coil U-V-2, V-phase coil V-W-2, The description will be continued on the assumption that the W-phase coil W-U-2 is a coil having the same 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 energized states of UV, VW, and WU 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 the energized states of UV, VW, and WU 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. The switching pattern to be applied is applied to the switching elements S7 to S12. At this time, the current flowing through the U-V energization path, the V-W energization path, and the W-U energization path related to the first inverter 71, and the U-V energization path, the V-W energization path, and W associated with the second inverter 72 Although the currents flowing through the -U 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 generate the maximum assist torque alone.

  Next, an outline of processing for determining the presence or absence of an ON failure (failure that does not return to OFF) of the open relays 71u, 71v, 71w, 72u, 72v, 72w by the ECU 80 (microcomputer 81) will be described.

  The ON failure is used in a concept including both ON fixation in a mechanical relay and ON short-circuit in a semiconductor relay.

  As described above, the release relays 71u, 71v, 71w are operated in response to the release command output from the microcomputer 81 when the power supply to the assist motor 22 cannot be stopped due to the failure of the switching elements S1 to S6. Opened. Further, the open relays 72u, 72v, 72w are, as described above, the open command output from the microcomputer 81 when the energization stop to the assist motor 22 becomes impossible due to the failure of the switching elements S7 to S12 or the like. It is released according to That is, in a situation where no abnormality occurs in the first inverter 71 and the second inverter 72, the open relays 71u, 71v, 71w, 72u, 72v, 72w are switched from ignition on (IG-ON) to ignition off (IG-OFF). ) Is normally closed (normally closed state). Therefore, a so-called ON failure may occur due to some factor. If an ON failure occurs, the release relays 71u, 71v, 71w, 72u, 72v, 72w cannot be opened when an abnormality occurs in either the first inverter 71 or the second inverter 72. End up. Therefore, the microcomputer 81 determines whether or not an ON failure has occurred in the open relays 71u, 71v, 71w, 72u, 72v, 72w at a predetermined timing.

  FIG. 5 is a diagram for explaining a method of determining whether or not an ON failure has occurred in the open relays 71u, 71v, 71w, 72u, 72v, 72w.

  As shown in FIG. 5, when the microcomputer 81 determines whether an ON failure has occurred in the open relays 71u, 71v, 71w, an open command (OFF command) is sent to any of the open relays 71u, 71v, 71w. And the first inverter 71 is controlled via the first pre-driver IC 82 so that the windings of the first system are energized through the open relay. Further, when the microcomputer 81 determines whether or not an ON failure has occurred in the open relays 72u, 72v, 72w, the microcomputer 81 outputs an open command (OFF command) to any of the open relays 72u, 72v, 72w, The second inverter 72 is controlled via the second pre-driver IC 83 so that the second winding is energized through the open relay. When the microcomputer 81 detects that energization is not detected by a current sensor that detects currents flowing through the U-V, V-W, and W-U energization paths, the open relay is opened according to the open command. Since it can be determined, it is determined that no ON failure has occurred. On the other hand, when energization is detected by the current sensor, the microcomputer 81 can determine that the open relay is not normally opened according to the open command (it remains in the ON state), and therefore an ON failure has occurred. It is determined that

  When it is determined that there is an ON failure, the ECU 80 (microcomputer 81) may output warning information indicating that the ON failure has occurred in the in-vehicle LAN to which the ECU 80 is connected. As a result, for example, the meter ECU connected to the in-vehicle LAN can receive warning information and display a warning that an ON failure has occurred in the meter, so the driver can bring the vehicle to a dealer or the like for repair. I can have you.

  Next, one of the windings of the first system and the winding of the second system realizes the normal operation of the assist motor 22 (operation for assisting the steering operation by the driver) while the other winding. A method for determining ON failure of an open relay provided between the drive circuit (one of the first inverter 71 and the second inverter) will be described. Thereafter, by operating the first inverter 71, the open motors 72u, 72v, 72v, 72v provided between the second system winding and the second inverter 72 while operating the assist motor 22 with only the first system winding. A case where it is determined whether or not an ON failure has occurred in any of 72w will be described.

  As a matter of course, among the first system winding and the second system winding, the winding for realizing the normal operation of the assist motor 22 and used for determining the presence or absence of an ON relay failure. The windings may be interchanged. That is, while the normal operation of the assist motor 22 is realized by the winding of the second system, an ON failure occurs in any of the open relays 71u, 71v, 71w provided between the winding of the first system and the first inverter 71. It may be determined whether or not it has occurred.

  FIG. 6 is a diagram illustrating an example of a mode of a current flowing through the assist motor when it is determined that an ON failure has occurred. Specifically, whether or not an ON failure has occurred in any of the open relays 72u and 72w in a state where a current flows through the U-phase coil U-V-1 of the first system (solid line arrow in the figure). This indicates a mode of current (broken arrows and dotted arrows in the figure) flowing in the second phase W-phase coil W-U-2 when it is determined that an ON failure has occurred. .

  It should be noted that whether or not there is an ON failure in the open relays 72u, 72v, and 72w is determined not only in a state in which a current is flowing through the U-phase coil U-V-1 of the first system but also in the V-phase coil V-W-1 or You may perform in the state in which the electric current is flowing into W phase coil W-U-1. Further, when determining whether or not an ON failure has occurred in any of the open relays 72u, 72v, 72w, the second is set so that the microcomputer 81 causes a current to flow through the U-phase coil U-V-2 of the second system. By outputting a drive command to the inverter 72 (second pre-driver IC 83), it may be determined whether or not any of the open relays 72u and 72v has an ON failure. Similarly, the microcomputer 81 outputs a drive command to the second inverter 72 (second pre-driver IC 83) so that a current flows through the V-phase coil V-W-2 of the second system, whereby the open relays 72v and 72w The presence or absence of any ON failure may be determined.

  In the example shown in FIG. 6, in the state where current flows from the U phase (U1 phase) to the V phase (V1 phase) of the first system, an opening command is output to either of the opening relays 72u and 72w. It is determined whether or not an ON failure has occurred in the relay. Then, as indicated by the broken line arrow in FIG. 6, the current from the W phase (W2 phase) to the U phase (U2 phase) flows through the second phase W-phase coil W-U-2. Based on the detection signal of the sensor, it is determined that an ON failure has occurred in the open relay.

  Here, since the assist motor 22 performs a normal operation using the winding of the first system, that is, an operation of assisting the steering operation by the driver, a current as indicated by a broken line arrow flows in the second system. If it does, it will affect the operation by the winding of the first system. Therefore, when the microcomputer 81 determines that an ON failure has occurred in the open relay, the microcomputer 81 immediately stops the drive command to the second inverter 72 (second pre-driver IC 83) for performing the ON failure determination, A drive command that suppresses the influence on the operation of one winding is output to the second inverter 72 (second pre-driver IC 83). Specifically, the second inverter 72 is controlled so that a current in a direction opposite to the current direction corresponding to the drive command for performing the ON failure determination flows in the second system winding (second pre-driver IC 83). Drive command).

  In the example shown in FIG. 6, as indicated by a dotted arrow, in accordance with a drive command from the microcomputer 81, a current in the opposite direction to the current that flows in the second phase W-phase coil W-U-2 at the time of ON failure determination ( Current flowing from the U2 phase to the W2 phase).

  In this way, in order to cancel the magnetic field due to the current flowing in the second system winding at the time of ON failure determination, a current in the opposite direction flows through the second system winding. The influence of the flowing current on the operation of the first system winding can be suppressed. That is, whether or not an ON failure has occurred in the open relays 72u, 72v, 72w provided between the second system winding and the second inverter 72 while suppressing the influence of the first system winding on the operation. Can be determined.

  Next, one of the windings of the first system and the winding of the second system realizes the normal operation of the assist motor 22 (operation for assisting the steering operation by the driver) while the other winding. The details of the operation of the electric power steering apparatus 20 in the case where it is determined whether there is an ON failure of the open relay provided between the drive circuit (one of the first inverter 71 and the second inverter) will be described.

  FIG. 7 is a timing chart showing an example of the operation of the electric power steering device 20 (ECU 80) when determining whether there is an ON failure of the open relay 72u provided between the winding of the second system and the second inverter 72. is there. Specifically, the total output (FIG. 7A) of both the first system winding and the second system winding in the assist motor 22 and a drive command to the first inverter 71 (first pre-driver IC 82). (FIG. 7 (b)), a current monitor (FIG. 7 (c)) showing the state of the current flowing through the windings of the first system, and the state of the command (ON command / OFF command) to the open relay 72u (FIG. 7 ( d)), a drive command (FIG. 7 (e)) to the second inverter 72 (second pre-driver IC 83), and a current monitor (FIG. 7 (f)) showing the state of the current flowing through the windings of the second system, respectively. This represents the time change.

  Prior to time t1 in the figure, the open relay 72u is in a closed state (ON state) based on a close command (ON command) from the microcomputer 81. Further, an ON failure has occurred in the open relay 72u at time t5 in the figure.

  As shown in FIGS. 7A and 7B, the assist motor 22 operates from time t1 to time t4 according to the steering operation by the driver. During this time, the assist motor 22 is operated only by the first system winding out of the first system winding and the second system winding. Specifically, the microcomputer 81 causes the current to flow through the U-phase coil U-V-1 from the U1 phase to the V1 phase from the time t1 to the time t2, and from the time t2 to the time t3, the V1 phase. From the time t3 to the time t4, further, the current flows from the W1 phase to the U1 phase to the W phase coil W-U-1 so that the current flows from the W1 phase to the W1 phase. Thus, a drive command is output to the first inverter 71 (first pre-driver IC 82).

  On the other hand, as shown in FIGS. 7D, 7E, and 7F, the presence or absence of an ON failure of the open relay 72u is determined between time t1 and time t2, using the second system winding. ing.

  At time t1, the microcomputer 81 outputs an open command (OFF command) to the open relay 72u. Then, a drive command is output to the second inverter 72 (second pre-driver IC 83) so that a current flows through the U-phase coil U-V-2 from the U2 phase to the V2 phase from time t1 to time t2. doing. At this time, since no current flows through the U-phase coil U-V-2 through the open relay 72u from time t1 to time t2, the microcomputer 81 determines that no ON failure has occurred in the open relay 72u. judge.

  As shown in FIGS. 7A and 7B, after an ON failure occurs in the open relay 72u at time t5, the assist motor is operated according to the steering operation by the driver from time t6 to time t11. 22 is activated. As in the period from time t1 to time t4, the assist motor 22 is operated only by the first system winding among the first system winding and the second system winding. Specifically, the microcomputer 81 causes the current to flow through the U-phase coil U-V-1 from the U1 phase to the V1 phase from time t6 to time t9, and from the time t9 to time t10. From the time t10 to the time t11, the current further flows from the W1 phase to the U1 phase to the W phase coil W-U-1 so that the current flows from the W1 phase to the W1 phase. Thus, a drive command is output to the first inverter 71 (first pre-driver IC 82).

  On the other hand, as shown in FIGS. 7 (d), (e), and (f), between time t6 and time t7 (before reaching time t9), a second system winding is used to open relay 72u. It is determined whether or not there is an ON failure. Specifically, during the period from time t6 to time t7, the microcomputer 81 causes the second inverter 72 (second pre-driver) so that current flows through the U-phase coil U-V-2 from the U2 phase to the V2 phase. IC 83) is outputting a drive command. At this time, since the current flows through the U-phase coil U-V-2 through the open relay 72u from time t6 to time t7, the microcomputer 81 determines that an ON failure has occurred in the open relay 72u. At the same time, the drive command to the second inverter 72 (second pre-driver IC 83) for flowing a current through the U-phase coil U-V-2 from the U2 phase to the V2 phase is stopped. In the period from time t7 to time t8 (period having the same length as from time t6 to time t7), the microcomputer 81 causes the current in the opposite direction to flow in the U-phase coil U-V-2 (V2-phase). The second inverter 72 is controlled (a drive command is output to the second pre-driver IC 83) so that a current flows through the U-phase coil U-V-2 from U to the U2-phase). Therefore, as shown in FIG. 7 (f), between time t7 and time t8, current in the opposite direction (current from the V2 phase to the U2 phase) flows through the open relay 72u to the U-phase coil U-V-2. ing.

  As shown in FIG. 7A, since current flows from the U2 phase to the V2 phase in the second phase U-phase coil U-V-2 between time t6 and time t7, The total output of the assist motor 22 increases. On the other hand, since the current in the opposite direction flows from the V2 phase to the U2 phase in the second phase U-phase coil U-V-2 between time t7 and time t8, from time t6 to time t7. The total output decreases so as to cancel out the increase in output. Thereby, the output (integrated value) as a whole period during which the assist motor 22 operates from time t6 to time t11 can be kept constant, and the total output of the assist motor 22 can be stabilized.

  As mentioned above, although the form for implementing this invention was explained in full detail, this invention is not limited to this specific embodiment, In the range of the summary of this invention described in the claim, various Can be modified or changed.

  For example, the electric power steering device in the above-described embodiment is an example of an electric motor control device that controls an electric motor including two windings, and the contents disclosed in the above-described embodiment (in particular, an ON relay failure) The contents relating to the determination of the presence or absence of) can be applied to any electric motor control device.

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 (electric motor control device)
22 Assist motor (electric motor)
24 Rotation angle sensor 26 Rudder angle sensor 71 First inverter (drive circuit)
71u, 71v, 71w Open relay (relay)
72 Second inverter (drive circuit)
72u, 72v, 72w Open relay (relay)
73 1st switch 74 2nd switch 80 ECU
81 Microcomputer (relay control unit, drive control unit, abnormality determination unit)
90 DC-DC converter

Claims (1)

An electric motor including two windings;
A drive circuit for energizing one of the two windings;
A relay provided between the one winding and the drive circuit;
A relay control unit for controlling the open / close state of the relay;
A drive control unit for controlling the operation of the drive circuit;
An abnormality determination unit that determines whether or not the relay has an ON failure, and when one of the windings is energized through the relay in a state in which an open command is output from the relay control unit to the relay An abnormality determination unit that determines that the relay has an ON failure,
The drive control unit is configured such that when the abnormality determination unit determines whether or not the relay has an ON failure, the first current that is defined in advance in the one winding flows through the relay. In addition to controlling the drive circuit, when the abnormality determination unit determines that the relay is in an ON failure, the second current in the direction opposite to the first current flows through the one coil through the relay. Controlling the drive circuit;
Electric motor control device.

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