JP2016096709A - Motor drive device and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an excessive current from flowing in an inverter or a coil group in a normal control system due to the affect of a faulty control system.SOLUTION: A motor drive device 30 includes a plurality of control systems 60A, 60B for individually supplying a drive current to a plurality of coil groups. The motor drive device sets a current command value individually for each of the control systems. A drive command is issued to drive circuits 63A, 63B of inverters 64A, 64B for each of the control systems on the basis of the current command value, and whereby a drive current is supplied from the inverters to the coil groups 22A, 22B. A fault in the inverters or the coil groups is detected for each of the control systems, and only the operation of the faulty control system is stopped or degraded. Therefor, an excessive current is prevented from flowing in an inverter or a coil group in a normal control system due to the affect of a faulty control system. Accordingly, there is no need of using a high rating component, and miniaturization and reduced costs in a motor drive device can be achieved.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a motor drive device and an electric power steering device.

2. Description of the Related Art Conventionally, an electric power steering device that assists a driver's steering is mounted on a transportation device such as an automobile. A conventional electric power steering device is described in, for example, Japanese Patent No. 5370139. The electric power steering apparatus of the document has a plurality of inverters and a plurality of sets of windings corresponding to the inverters (see claim 1, paragraph 0016, etc.). Then, feedback control is performed so that a current corresponding to the command value flows from the inverter to a plurality of sets of windings. In other words, the electric power steering device of the document assists the driver's steering force by driving the electric motor with a multi-system drive circuit.
Japanese Patent No. 5370139

  In addition, in the electric power steering apparatus disclosed in Japanese Patent No. 5370139, when an abnormality occurs in one of the multi-system drive circuits, current is continuously supplied from the normal power converter to the corresponding winding. To do. As a result, the steering force of the driver can be continuously supported (see paragraph 0007 and the like).

  However, in this document, the current command value set by the motor drive control device is the total value of the currents supplied by the two inverters to the two sets of three-phase windings (see paragraph 0017 and the like). For this reason, when an abnormality occurs in a certain drive circuit, feedback control based on an abnormal input value is performed before the motor drive control device recognizes the occurrence of the failure and takes a countermeasure. Then, in a normal system, excessive current temporarily flows in the inverter and the winding, which may cause an abnormal steering operation.

  Moreover, in the structure of the said literature, it is necessary to use the component with a high rating which can endure the overload of the electric current mentioned above for an inverter and a coil | winding. This is one of the factors that hinder downsizing and cost reduction of the apparatus.

  An object of the present invention is to provide a motor drive device that can prevent an excessive current from flowing to an inverter or a coil group of a normal control system due to the influence of a failed control system.

  An exemplary first invention of the present application is a motor drive device for driving a motor, wherein N is an integer of 2 or more, and any integer from 1 to N is n, and the first coil group included in the motor To the Nth coil group. The nth control system includes an nth inverter for supplying a drive current to the nth coil group, and an external control unit. An n-th current command value setting unit for setting an n-th current command value in accordance with an input signal from the input signal, and an n-th control unit for giving a drive instruction to the drive circuit of the n-th inverter based on the n-th current command value And an nth failure detection unit that detects a failure of the nth inverter or the nth coil group, and stops the operation of the nth control system when the nth failure detection unit detects the failure. Or degenerate.

  According to the exemplary first invention of the present application, the current command value is individually set for each control system. Further, a failure in the inverter or coil group is detected for each control system, and only the operation of the failed control system is stopped or degenerated. For this reason, it can prevent that an excessive electric current flows into the inverter or coil group of a normal control system by the influence of the failed control system. Therefore, it is not necessary to use high-rated parts, and the motor drive device can be reduced in size and cost.

FIG. 1 is a schematic diagram of an electric power steering apparatus. FIG. 2 is a block diagram showing the configuration of the motor drive device. FIG. 3 is a functional block diagram of the arithmetic device. FIG. 4 is a flowchart showing a flow of fail-safe processing. FIG. 5 is a flowchart showing a flow of fail-safe processing according to the modification. FIG. 6 is a functional block diagram of an arithmetic device according to a modification. FIG. 7 is a block diagram of a motor drive device according to a modification. FIG. 8 is a block diagram showing the configuration of the motor drive device according to the second embodiment. FIG. 9 is a functional block diagram of the main arithmetic unit and the preliminary arithmetic unit according to the second embodiment. FIG. 10 is a functional block diagram of the main arithmetic unit and the preliminary arithmetic unit according to the modification. FIG. 11 is a block diagram illustrating a configuration of a motor driving device according to a modification. FIG. 12 is a block diagram illustrating a configuration of a motor driving device according to a modification.

  Hereinafter, examples of the motor drive device and the electric power steering device will be described with reference to the drawings.

<1. First Embodiment>
<1-1. Configuration of electric power steering device>
FIG. 1 is a schematic diagram of an electric power steering apparatus 1 including a motor drive device 30 according to the first embodiment. The electric power steering device 1 is a device that assists the driver's steering in a transportation device such as an automobile. As shown in FIG. 1, the electric power steering device 1 according to the present embodiment includes a torque sensor 10, a motor 20, and a motor drive device 30.

  The torque sensor 10 is attached to the steering shaft 92. When the driver operates the steering wheel 91 to rotate the steering shaft 92, the torque sensor 10 detects the torque applied to the steering shaft 92. A torque signal that is a detection signal of the torque sensor 10 is output from the torque sensor 10 to the motor drive device 30. The motor drive device 30 drives the motor 20 based on the torque signal input from the torque sensor 10. The motor driving device 30 may refer to not only the torque signal but also other information (for example, vehicle speed).

  The motor drive device 30 supplies drive current to the motor 20 by using power obtained from the power supply source 40. The driving force generated from the motor 20 is transmitted to the wheel 93 via the gear box 50. Thereby, the rudder angle of the wheel 93 changes. Thus, the electric power steering apparatus 1 amplifies the torque of the steering shaft 92 by the motor 20 and changes the steering angle of the wheel 93. Therefore, the driver can operate the steering wheel 91 with a light force.

<1-2. Configuration of Motor Drive Device>
Next, the configuration of the motor drive device 30 used in the electric power steering device 1 will be described. FIG. 2 is a block diagram showing the configuration of the motor drive device 30. As shown in FIG. 2, the motor driving device 30 is configured by an electric circuit having an arithmetic device 31 such as a microcontroller. The motor drive device 30 is electrically connected to the torque sensor 10, the motor 20, and the power supply source 40 (see FIG. 1).

  In the present embodiment, a three-phase synchronous brushless motor is used for the motor 20 of the electric power steering apparatus 1. When the motor 20 is driven, U-phase, V-phase, and W-phase currents are supplied from the motor drive device 30 to the plurality of coils 21 </ b> A and 21 </ b> B in the motor 20. Then, a rotating magnetic field is generated between the stator having the coils 21A and 21B and the rotor having the magnet. As a result, the rotor rotates with respect to the stator of the motor 20.

  As shown in FIG. 2, the motor 20 of the present embodiment has two sets of coil groups composed of U-phase, V-phase, and W-phase coils. Hereinafter, these two sets of coil groups are referred to as a first coil group 22A and a second coil group 22B, respectively. The three coils 21A of the first coil group 22A and the three coils 21B of the second coil group 22B are respectively connected by star connection. However, the first coil group 22A and the second coil group 22B may be connected by delta connection, respectively.

  The motor drive device 30 supplies drive currents individually to the first coil group 22A and the second coil group 22B. That is, the motor drive device 30 includes a first control system 60A that supplies a drive current to the first coil group 22A and a second control system 60B that supplies a drive current to the second coil group 22B. .

  FIG. 3 is a functional block diagram of the arithmetic device 31. As shown in FIGS. 2 and 3, the first control system 60A includes a first current command value setting unit 61A, a first feedback control unit 62A, a first inverter drive circuit 63A, a first inverter 64A, and a first current cut-off unit. 65A, a first current detection circuit 66A, and a first failure detection unit 67A. The functions of the first current command value setting unit 61A, the first feedback control unit 62A, and the first failure detection unit 67A are performed by the CPU in the calculation device 31 performing calculation processing based on a preset program. Realized.

  A torque signal output from the torque sensor 10 and other various signals are input to the first current command value setting unit 61A as an input signal 71A. Then, the first current command value setting unit 61A sets a first current command value 72A corresponding to the input signal 71A. In the arithmetic unit 31, reference data called an assist map that prescribes the correspondence between the input signal 71A and the first current command value 72A is stored in advance. The first current command value setting unit 61A determines a first current command value 72A corresponding to the input signal 71A based on the assist map.

  The first feedback control unit 62A is configured based on a first current command value 72A obtained from the first current command value setting unit 61A and a detection signal 76A of a first current detection circuit 66A described later, and a first inverter drive circuit 63A. Is given a drive instruction 73A. Specifically, the drive instruction 73A is generated so that the current value detected by the first current detection circuit 66A approaches the current value corresponding to the first current command value 72A. The drive instruction 73A includes information on the duty ratio of the PWM signal 74A supplied to the first inverter 64A. The generated drive instruction 73A is output as an electrical signal from the arithmetic device 31, and is provided to the first inverter drive circuit 63A.

  The first inverter drive circuit 63A is an electric circuit for operating the first inverter 64A. The first inverter drive circuit 63A supplies a PWM signal 74A, which is a pulse wave, to each of the six switching elements 68A of the first inverter 64A in accordance with the drive instruction 73A output from the arithmetic device 31. The PWM signal 74A supplied to each switching element 68A has a duty ratio specified by the drive instruction 73A.

  The first inverter 64A is a power converter that generates a drive current 75A based on the PWM signal 74A. As shown in FIG. 2, the first inverter 64A includes six switching elements 68A. For example, a transistor such as an FET is used as the switching element 68A. In the example of FIG. 2, three sets of two switching elements 68A connected in series are provided in parallel between the power supply voltage V1 and the ground voltage V0.

  One end of each of the three coils 21A of the first coil group 22A is connected to each other at a neutral point 23A. The other end of each of the three coils 21A is connected between the + side switching element 68A and the − side switching element 68A of each of the three sets of switching elements 68A of the first inverter 64A. When the six switching elements 68A are turned on / off by the PWM signal 74A, the drive current 75A is supplied from the first inverter 64A to the coils 21A of the respective phases of the first coil group 22A according to the on / off state.

  As shown in FIG. 2, the first inverter 64A has three first shunt resistors 69A. The three first shunt resistors 69A are interposed between the negative side switching elements 68A of the three sets of switching elements 68A and the ground voltage V0. When the drive current 75A is supplied to the first coil group 22A, currents of respective phases returning from the first coil group 22A to the first inverter 64A flow through the three first shunt resistors 69A.

  65 A of 1st electric current interruption parts are provided on the path | route of each current of three phases between 64 A of 1st inverters, and 22 A of 1st coils. For example, a mechanical relay or FET is used for the first current interrupting unit 65A. Based on the signal from the arithmetic device 31, the first current interrupting unit 65A can switch the current path between the energized state and the interrupted state for each phase.

  The first current detection circuit 66A is an electric circuit for detecting a current flowing through the first shunt resistor 69A. The first current detection circuit 66A generates a detection signal 76A indicating a current (shunt current) flowing through each first shunt resistor 69A by measuring a potential difference between both ends of the three first shunt resistors 69A. The generated detection signal 76A is sent from the first current detection circuit 66A to the arithmetic unit 31.

  The first failure detector 67A detects the presence or absence of a failure in the first inverter 64A or the first coil group 22A based on the detection signal 76A obtained from the first current detection circuit 66A. Here, it is determined for each phase whether or not the values of the three shunt currents indicated by the detection signal 76A are values within the allowable range. If there is a shunt current that is out of the allowable range, it is determined that a failure has occurred in the phase corresponding to the shunt current of the first inverter 64A or the first coil group 22A. The detection result 77A of the first failure detection unit 67A is input to the first feedback control unit 62A.

  A sensor (not shown) for monitoring the operating state of the switching element 68A is provided inside the first inverter 64A. The first failure detector 67A may detect the presence or absence of a failure in the first inverter 64A based not only on the shunt current but also on the detection signal of the sensor in the first inverter 64A. Further, the first failure detection unit 67A may detect the presence or absence of a failure in the first coil group 22A based on the voltage value of each part of the first coil group 22A.

  The second control system 60B has a configuration equivalent to that of the first control system 60A. That is, as shown in FIGS. 2 and 3, the second control system 60B includes a second current command value setting unit 61B, a second feedback control unit 62B, a second inverter drive circuit 63B, a second inverter 64B, and a second current. It has the interruption | blocking part 65B, the 2nd electric current detection circuit 66B, and the 2nd failure detection part 67B. The second control system 60B supplies the drive current 75B to the second coil group 22B by operating these components. In addition, since detailed operation | movement of each part in the 2nd control system 60B is the same as that of the 1st control system 60A mentioned above, duplication description is abbreviate | omitted. In FIGS. 2 and 3, reference numerals 71 </ b> B to 77 </ b> B corresponding to signals 71 </ b> A to 77 </ b> A between the respective parts of the first control system 60 </ b> A are attached to signals exchanged between the respective parts in the second control system 60 </ b> B.

<1-3. About the fail-safe function of the motor drive device>
This motor drive device 30 is electrically driven while preventing malfunction of the device due to failure when any of the first inverter 64A, the first coil group 22A, the second inverter 64B, and the second coil group 22B fails. A fail-safe function for continuing the operation of the power steering apparatus 1 is provided. Below, the said fail safe function is demonstrated, referring the flowchart of FIG.

  As shown in FIG. 4, during the operation of the motor drive device 30, the arithmetic device 31 repeatedly monitors the presence / absence of a failure in the first control system 60A and the presence / absence of a failure in the second control system 60B (step S11, S14). Specifically, the first failure detection unit 67A in the arithmetic device 31 monitors whether or not there is a failure in the first inverter 64A or the first coil group 22A in the first control system 60A (step S11). Then, the first failure detection unit 67A notifies the detection result to the first feedback control unit 62A. In addition, the second failure detection unit 67B in the arithmetic device 31 monitors whether or not there is a failure in the second inverter 64B or the second coil group 22B in the second control system 60B (step S14). Then, the second failure detection unit 67B notifies the detection result to the second feedback control unit 62B.

  Note that the arithmetic device 31 may execute the detection process of the first failure detection unit 67A and the detection process of the second failure detection unit 67B in parallel with each other or sequentially and alternately. If the detection process of the first failure detection unit 67A and the detection process of the second failure detection unit 67B are executed in parallel with each other, the processing time required for the failure detection can be shortened. On the other hand, if the detection process of the first failure detection unit 67A and the detection process of the second failure detection unit 67B are executed alternately in sequence, the failure can be detected with simple logic.

  When the first failure detection unit 67A has not detected a failure (no in step S11), the first feedback control unit 62A continues normal operation (step S12). That is, the first feedback control unit 62A gives a drive instruction 73A to the first inverter drive circuit 63A based on the first current command value 72A and the detection signal 76A of the first current detection circuit 66A.

  When a failure occurs in the first inverter 64A or the first coil group 22A, the first failure detector 67A detects the failure (yes in step S11). Then, the first failure detection unit 67A notifies the first feedback control unit 62A of a detection result indicating a failure. Then, the first feedback control unit 62A stops the operation of the first control system 60A (Step S13).

  In step S13, the first feedback control unit 62A stops, for example, a drive instruction 73A to the first inverter drive circuit 63A. As a result, the operation of the first inverter 64A is stopped so that the drive current 75A is not supplied to the first coil group 22A. In addition, the first feedback control unit 62A may block the path of the drive current 75A in the first current blocking unit 65A. If the path of the drive current 75A is interrupted, the occurrence of electromagnetic braking by the first coil group 22A can be prevented. Therefore, it is possible to prevent a load from being applied to the rotation of the motor 20 due to the influence of the stopped first coil group 22A.

  On the other hand, the second control system 60B performs failure detection and operation stop determination independently of the first control system 60A. When the second failure detection unit 67B has not detected a failure (no in step S14), the second feedback control unit 62B continues normal operation (step S15). That is, the second feedback control unit 62B gives a drive instruction 73B to the second inverter drive circuit 63B based on the second current command value 72B and the detection signal 76B of the second current detection circuit 66B.

  When a failure occurs in the second inverter 64B or the second coil group 22B, the second failure detector 67B detects the failure (yes in step S14). Then, the second failure detection unit 67B notifies the second feedback control unit 62B of the detection result indicating the failure. Then, the second feedback control unit 62B stops the operation of the second control system 60B (Step S16).

  In step S16, for example, the second feedback control unit 62B stops the drive instruction 73B to the second inverter drive circuit 63B. As a result, the operation of the second inverter 64B is stopped so that the drive current 75B is not supplied to the second coil group 22B. Further, the second feedback control unit 62B may block the path of the drive current 75B in the second current blocking unit 65B. If the path of the drive current 75B is interrupted, the occurrence of electromagnetic braking by the second coil group 22B can be prevented. Therefore, it is possible to prevent a load from being applied to the rotation of the motor 20 due to the influence of the stopped second coil group 22B.

  As described above, in the motor drive device 30 of the present embodiment, the current command values 72A and 72B are individually set in the first control system 60A and the second control system 60B. Further, the first control system 60A and the second control system 60B individually detect the failure of the inverter or the coil group, and stop only the operation of the failed control system. For this reason, when a failure occurs in one of the first control system 60A and the second control system 60B, the operation of the electric power steering apparatus 1 can be continued by the other control system. Further, since the feedback path is independent for each control system, an excessive current does not flow through the inverter or coil group of the normal control system due to the influence of the failed control system. Therefore, it is not necessary to use high-rated parts, and the motor drive device 30 can be reduced in size and cost.

  In particular, in the present embodiment, in one arithmetic unit 31, the first current command value setting unit 61A, the first feedback control unit 62A, the first failure detection unit 67A, the second current command value setting unit 61B, the second feedback The functions of the control unit 62B and the second failure detection unit 67B are executed. For this reason, the operation of the two control systems 60 </ b> A and 60 </ b> B can be realized without arranging a plurality of arithmetic devices 31 in the motor drive device 30. Thereby, the motor drive device 30 can be further reduced in size and cost.

<1-4. Modification>
Subsequently, a modification of the first embodiment will be described.

  FIG. 5 is a flowchart showing a flow of fail-safe processing according to a modification. In the example of FIG. 5 as well, as in the above embodiment, the arithmetic unit 31 repeatedly monitors the presence or absence of a failure in the first control system 60A and the presence or absence of a failure in the second control system 60B (step S21). , S26).

  When the first failure detection unit 67A has not detected a failure (no in step S21), the first feedback control unit 62A continues normal operation (step S22). In addition, when the second failure detection unit 67B has not detected a failure (no in step S26), the second feedback control unit 62B continues normal operation (step S27).

  When a failure occurs in the first inverter 64A or the first coil group 22A, the first failure detector 67A detects the failure (yes in step S21). At this time, in the example of FIG. 5, the first failure detection unit 67A analyzes the state of the detected failure. Specifically, it is determined whether or not so-called two-phase energization that generates a rotating magnetic field with only the two-phase drive current 75A out of the three-phase drive current 75A of the first control system 60A is possible (step). S23).

  If two or more of the three phases have failed and it is determined that two-phase energization is impossible (no in step S23), the first feedback control unit 62A stops the operation of the first control system 60A (step S24). If it is determined that two of the three phases are normal and two-phase energization is possible (yes in step S23), the first feedback control unit 62A drives the first inverter drive circuit 63A with two-phase energization. Give instructions. As a result, only the two-phase drive current is supplied from the first inverter 64A to the first coil group 22A.

  Moreover, as shown in FIG. 5, also in the 2nd control system 60B, the process of step S26-30 similar to step S21-25 in the 1st control system 60A is performed. In this way, when the first control system 60A or the second control system 60B fails, even in the failed control system, the degenerate operation by two-phase energization is performed without completely stopping the function of the coil group. be able to. That is, even in a failed control system, the operation can be continued while reducing the function.

  That is, in the example of FIG. 5, when only one phase of one control system of the first control system 60A and the second control system 60B fails, not only the three phases of the normal control system but also the failed control system. Torque can be generated in the motor 20 using a total of five phases including two normal phases of the system. Therefore, higher torque can be obtained than when only three phases of a normal control system are used. At this time, the three phases of the normal control system and the normal two phases of the failed control system may be controlled independently, or a total of five phases may be controlled comprehensively.

  FIG. 6 is a functional block diagram of an arithmetic device 31 according to another modification. In the example of FIG. 6, a first arithmetic unit 31A in charge of the first control system 60A and a second arithmetic unit 31B in charge of the second control system 60B are separately provided in the motor drive device 30. Yes. The first arithmetic device 31A executes the functions of the first current command value setting unit 61A, the first feedback control unit 62A, and the first failure detection unit 67A of the first control system 60A. The second arithmetic unit 31B executes the functions of the second current command value setting unit 61B, the second feedback control unit 62B, and the second failure detection unit 67B of the second control system 60B.

  Thus, in the example of FIG. 6, one arithmetic unit is used for each control system. Therefore, even if one of the first arithmetic device 31A and the second arithmetic device 31B fails, if the other arithmetic device is normal, the control system in charge of the other arithmetic device can be operated normally. it can. Therefore, the operation can be continued without completely stopping the electric power steering apparatus 1.

  FIG. 7 is a block diagram of a motor drive device 30 according to another modification. In the example of FIG. 7, a main arithmetic device 31 and a preliminary arithmetic device 32 are provided in the motor drive device 30. For the main arithmetic unit 31 and the preliminary arithmetic unit 32, for example, a microcontroller having a CPU is used. The main arithmetic unit 31 performs the same operation as the arithmetic unit 31 in the above embodiment. That is, the main arithmetic unit 31 controls both the first control system 60A and the second control system 60B in normal times. When the main arithmetic unit 31 breaks down, the preliminary arithmetic unit 32 performs only the control of the second control system 60B as an emergency measure.

  The preliminary calculation device 32 can execute functions equivalent to those of the second current command value setting unit 61B, the second feedback control unit 62B, and the second failure detection unit 67B described above by a preset program. In addition, the standby arithmetic device 32 always communicates with the main arithmetic device 31 during normal times to monitor whether the main arithmetic device 31 is operating normally. When the preliminary arithmetic unit 32 determines that the main arithmetic unit 31 has failed, it gives a switching signal to the switching circuit 33. Then, in the switching circuit 33, the connection between the main arithmetic unit 31 and the second inverter drive circuit 63B is cut off, and the preliminary arithmetic unit 32 and the second inverter drive circuit 63B are connected. Thereby, it becomes possible to supply a drive instruction from the preliminary arithmetic unit 32 to the second inverter drive circuit 63B.

  In this way, even if the main arithmetic unit 31 out of the main arithmetic unit 31 and the preliminary arithmetic unit 32 fails, if the preliminary arithmetic unit 32 is normal, only the second control system 60B is used for the electric power steering apparatus 1. Can be continued.

  In the example of FIG. 7, the second current cut-off unit 65B opens or cuts off the current path based on a signal from the preliminary calculation device 32 instead of the main calculation device 31. In this way, there is no possibility that the second current interrupting unit 65B receives an abnormal on / off operation from the main arithmetic unit 31 when the main arithmetic unit 31 fails. Therefore, the current path of the second control system 60B controlled by the preliminary calculation device 32 can be reliably opened when the main calculation device 31 fails.

  In the example of FIG. 7, if both the main arithmetic unit 31 and the preliminary arithmetic unit 32 fail, the driver has to operate the steering wheel 91 without receiving the assistance of the electric power steering device 1. Absent. At this time, if the first current interrupting part 65A or the second current interrupting part 65B is opened, the steering wheel 91 may become heavier due to the electromagnetic brake. Therefore, when both the main arithmetic unit 31 and the preliminary arithmetic unit 32 fail, both the first current interrupting unit 65A and the second current interrupting unit 65B may be switched to the interrupting state.

  Further, in the above embodiment, the motor 20 has two sets of coil groups 22A and 22B, and the motor drive device 30 has two control systems 60A and 60B corresponding thereto. However, the motor 20 may have three or more sets of coils, and the motor driving device 30 may have three or more control systems correspondingly.

  That is, when N is generalized as an integer of 2 or more, the motor 20 may include the first coil group to the Nth coil group. In that case, it is only necessary that the motor driving device 30 be provided with a first control system to an Nth control system for supplying a drive current to each coil group individually. Further, when an arbitrary integer from 1 to N is n, the n-th control system that is each control system from the first control system to the N-th control system is the same as each control system in the above embodiment. It only needs to have an n-th current command value setting unit, an n-th feedback control unit, an n-th inverter drive circuit, an n-th inverter, an n-th current cut-off unit, an n-th current detection circuit, and an n-th fault detection unit.

  The nth current command value setting unit sets a current command value in the nth control system. The nth failure detection unit detects a failure in the nth inverter or the nth coil group. Then, only the operation of the control system in which the failure is detected is stopped or degenerated. If it does in this way, it can prevent that an excessive electric current flows into the inverter or coil group of a normal control system by the influence of the failed control system. Therefore, it is not necessary to use high-rated parts, and the motor drive device can be reduced in size and cost.

  Moreover, you may apply said motor drive device 30 to apparatuses other than a power steering apparatus. For example, you may drive the motor used for the other site | part of transport equipment with said motor drive device 30. FIG. Moreover, you may drive the motor mounted in apparatuses other than motor vehicles, such as an industrial robot, by said motor drive device 30. FIG.

  Further, the detailed configuration of the motor drive device may be different from the configuration shown in each drawing of the present application. For example, part of the functions of the arithmetic device may be realized by an electric circuit. Moreover, you may combine suitably each element which appeared in said embodiment and modification in the range which does not produce inconsistency.

<2. Second Embodiment>
<2-1. About Configuration and Operation of Motor Drive Device>
Next, the motor drive device 30 according to the second embodiment will be described. FIG. 8 is a block diagram showing the configuration of the motor drive device 30 according to the second embodiment. The motor drive device 30 in FIG. 8 is used in the electric power steering device 1 as in the first embodiment. Below, it demonstrates centering around difference with 1st Embodiment, and duplication description is abbreviate | omitted about the part which is common in 1st Embodiment.

  Also in the present embodiment, the motor 20 includes a first coil group 22A and a second coil group 22B. The motor drive device 30 includes a first control system 60A that supplies a drive current to the first coil group 22A and a second control system 60B that supplies a drive current to the second coil group 22B. The motor drive device 30 drives the motor 20 by supplying drive currents individually to the two coil groups 22A and 22B using the first control system 60A and the second control system 60B.

  In the present embodiment, a main arithmetic unit 31 and a preliminary arithmetic unit 32 are provided in an electric circuit constituting the motor driving device 30. For the main arithmetic unit 31 and the preliminary arithmetic unit 32, for example, a microcontroller having a CPU is used. The main arithmetic unit 31 performs the same operation as the arithmetic unit 31 in the above embodiment. That is, the main arithmetic unit 31 controls both the first control system 60A and the second control system 60B in normal times. When the main arithmetic unit 31 breaks down, the preliminary arithmetic unit 32 performs only the control of the second control system 60B as an emergency measure.

  FIG. 9 is a functional block diagram of the main arithmetic unit 31 and the preliminary arithmetic unit 32 according to the second embodiment. As shown in FIGS. 8 and 9, the first control system 60A includes a first current command value setting unit 61A, a first feedback control unit 62A, a first inverter drive circuit 63A, a first inverter 64A, and a first current cutoff unit. 65A, a first current detection circuit 66A, and a first failure detection unit 67A. Each function of the first current command value setting unit 61A, the first feedback control unit 62A, and the first failure detection unit 67A is performed by the CPU in the main arithmetic device 31 based on a preset program. Is realized. The first control system 60A supplies the drive current to the first coil group 22A by operating these units 61A to 67A.

  The second control system 60B includes a second current command value setting unit 61B, a second feedback control unit 62B, a second inverter drive circuit 63B, a second inverter 64B, a second current cutoff unit 65B, a second current detection circuit 66B, and It has the 2nd failure detection part 67B. Each function of the second current command value setting unit 61B, the second feedback control unit 62B, and the second failure detection unit 67B is performed by the CPU in the main arithmetic unit 31 based on a preset program. Is realized. The second control system 60B supplies a drive current to the second coil group 22B by operating these units 61B to 67B.

  Note that detailed operations of the respective units 61A to 67A and 61B to 67B of the first control system 60A and the second control system 60B are the same as those in the first embodiment, and thus redundant description is omitted. In FIGS. 8 and 9, the same reference numerals 71 </ b> A to 77 </ b> A and 71 </ b> B to 77 </ b> B as those in the first embodiment are attached to signals exchanged between the respective parts in the first control system 60 </ b> A and the second control system 60 </ b> B.

  In the motor drive device 30, when the main arithmetic device 31 is not out of order, the main arithmetic device 31 is used to execute the operations of the first control system 60A and the second control system 60B. That is, the same processing as the processing of FIG. 4 described in the first embodiment is performed. Main processing unit 31 sets current command values 72A and 72B individually for each control system. The main arithmetic unit 31 detects a failure of the inverters 64A and 64B or the coil groups 22A and 22B for each control system, and stops or degenerates only the operation of the failed control system. For this reason, it can prevent that an excessive electric current flows into the inverter or coil group of a normal control system by the influence of the failed control system. Therefore, it is not necessary to use high-rated parts, and the motor drive device 30 can be reduced in size and cost as in the first embodiment.

  However, as shown in FIGS. 8 and 9, in the motor drive device 30, even when the main arithmetic unit 31 is operating normally, the detection signal of the sensor in the second inverter 64B, the second The voltage value of each part of the coil group 22B is input to the main arithmetic unit 31 via the preliminary arithmetic unit 32. Further, a signal for switching the second current interrupting unit 65B is output from the main arithmetic unit 31 to the second current interrupting unit 65B via the preliminary arithmetic unit 32. As described above, in the motor drive device 30, the main arithmetic device 31 performs a part of input / output of information with respect to the second control system via the preliminary arithmetic device 32. In this way, the number of terminals of the main arithmetic unit 31 can be suppressed. As a result, for example, it is possible to use semiconductor elements having the same number of terminals for the main arithmetic unit 31 and the preliminary arithmetic unit 32. Thereby, the manufacturing cost of the motor drive device 30 can be further reduced.

  On the other hand, as shown in FIG. 9, the preliminary calculation device 32 includes a preliminary second current command value setting unit 61b, a preliminary second feedback control unit 62b, and a preliminary second failure detection unit 67b. The spare second current command value setting unit 61b, the spare second feedback control unit 62b, and the spare second failure detection unit 67b are the second current command value setting unit 61B, the second feedback control unit 62B, and the second failure described above. Each of the detection units 67B has the same function. Each function of the spare second current command value setting unit 61b, the spare second feedback control unit 62b, and the spare second failure detection unit 67b is calculated by the CPU in the spare arithmetic device 32 based on a preset program. It is realized by doing.

  In addition, the preliminary calculation device 32 includes a monitoring unit 80 b that monitors the presence or absence of a failure in the main calculation device 31. The function of the monitoring unit 80b is also realized by the CPU in the preliminary calculation device 32 performing calculation processing based on a preset program. When the main arithmetic unit 31 is operating normally, the preliminary arithmetic unit 32 does not control either the first control system 60A or the second control system 60B. That is, the preliminary arithmetic unit 32 outputs neither the drive instruction 73A to the first inverter drive circuit 63A nor the drive instruction 73B to the second inverter drive circuit 63B. However, the monitoring unit 80b of the preliminary calculation device 32 constantly monitors the presence or absence of a failure in the main calculation device 31.

  Further, as shown in FIG. 8, the motor driving device 30 has a switching circuit 33. For example, a logic IC is used for the switching circuit 33. The switching circuit 33 alternatively connects the main arithmetic unit 31 and the preliminary arithmetic unit 32 to the second inverter drive circuit 63B based on the switching signal 78b output from the monitoring unit 80b of the preliminary arithmetic unit 32. That is, the switching circuit 33 outputs the drive instruction 73B output from the main arithmetic unit 31 to the second inverter drive circuit 63B connected to the second inverter 64B, and outputs from the preliminary arithmetic unit 32. The second state in which the drive instruction 73b is input is switched based on the switching signal 78b.

  When the monitoring unit 80b of the preliminary arithmetic unit 32 detects a failure of the main arithmetic unit 31, the monitoring unit 80b outputs a switching signal 78b instructing the switching circuit 33 to switch from the first state to the second state. When the switching circuit 33 receives the switching signal 78b, the connection between the main arithmetic device 31 and the second inverter drive circuit 63B is cut off, and the preliminary arithmetic device 32 and the second inverter drive circuit 63B are connected. As a result, the backup second current command value setting unit 61b, the backup second feedback control unit 62b, and the backup second failure detection unit 67b in the backup computing device 32 are replaced with the second current command value setting unit in the main computing device 31. The functions of 61B, second feedback control unit 62B, and second failure detection unit 67B can be substituted. The motor drive device 30 includes a backup second current command value setting unit 61b, a backup second feedback control unit 62b, a second inverter drive circuit 63B, a second inverter 64B, a second current cut-off unit 65B, a second current detection circuit 66B, And the 2nd control system 60B is operated urgently using the preliminary arithmetic unit 32.

  As described above, in the motor drive device 30 of the present embodiment, the second control system 60B out of the first control system 60A and the second control system 60B uses the preliminary calculation device 32 for emergency when the main calculation device 31 fails. It is set as an emergency control system that operates automatically. For this reason, even if the main arithmetic unit 31 breaks down, if the preliminary arithmetic unit 32 is normal, the driving of the motor 20 can be continued using the second control system 60B which is an emergency control system.

  In particular, in this motor drive device 30, not the main arithmetic device 31 itself but the preliminary arithmetic device 32 monitors the failure of the main arithmetic device 31. Thereby, the failure of the main arithmetic unit 31 can be detected with high accuracy. In addition, the motor drive device 30 is provided with a switching circuit 33 separately from the main arithmetic device 31 and the preliminary arithmetic device 32. For this reason, switching from the main arithmetic unit 31 to the preliminary arithmetic unit 32 can be reliably performed by the logic circuit. Furthermore, the switching circuit 33 performs the switching operation based on the switching signal 78b from the spare arithmetic device 32 that is not in failure, instead of the signal from the failed main arithmetic device 31. Thereby, the switching circuit 33 can be switched more reliably.

  In the motor drive device 30, the preliminary calculation device 32 controls the second control system with priority over the main calculation device 31. That is, when signals are input to the switching circuit 33 from both the main arithmetic unit 31 and the preliminary arithmetic unit 32, the switching circuit 33 preferentially adopts the signal from the preliminary arithmetic unit 32 and performs the switching operation. The drive instruction is supplied to the second inverter 64B. For this reason, even if an abnormal signal is input from the main arithmetic unit 31 to the switching circuit 33 when the main arithmetic unit 31 fails, the switching circuit 33 blocks the signal. Therefore, the second inverter 64B can be normally controlled based on the signal input from the normal preliminary calculation device 32.

<2-2. Modification>
Subsequently, a modification of the second embodiment will be described.

  FIG. 10 is a functional block diagram of the main arithmetic unit 31 and the preliminary arithmetic unit 32 according to a modification. In the example of FIG. 10, a first power supply circuit 311 and a first monitoring circuit 312 are provided outside the main processing unit 31 instead of the monitoring unit 80 b in the preliminary processing unit 32. The first power supply circuit 311 supplies power to the main arithmetic unit 31 and the first monitoring circuit 312. The first monitoring circuit 312 monitors the presence or absence of a failure in the main arithmetic unit 31. 10 also includes a second power supply circuit 321 and a second monitoring circuit 322 outside the preliminary calculation device 32. The second power supply circuit 321 supplies power to the preliminary calculation device 32 and the second monitoring circuit 322. The second monitoring circuit 322 monitors the presence or absence of a failure in the preliminary calculation device 32.

  As described above, in the motor drive device 30 of FIG. 10, the power supply circuits 311 and 321 are individually provided for the main arithmetic device 31 and the preliminary arithmetic device 32. For this reason, even if one of the two power supply circuits 311 and 321 fails, if the other power supply circuit is normal, the driving of the motor 20 can be continued using an arithmetic unit that receives power from the power supply circuit. it can.

  FIG. 11 is a block diagram showing a configuration of a motor drive device 30 according to another modification. In the example of FIG. 11, a single semiconductor element 34 including a main arithmetic unit 31 and a preliminary arithmetic unit 32 is provided in an electric circuit constituting the motor driving device 30. Thus, if the main arithmetic unit 31 and the preliminary arithmetic unit 32 are incorporated in the semiconductor element 34 as a single package, the motor drive unit 30 can be further downsized.

  FIG. 12 is a block diagram showing a configuration of a motor drive device 30 according to another modification. In FIG. 12, the detection circuit is not shown in order to avoid complication of the drawing. In the example of FIG. 12, two switching circuits 33 </ b> A and 33 </ b> B are provided in the electric circuit constituting the motor drive device 30. The main arithmetic unit 31 is connected to the first inverter drive circuit 63A and the second inverter drive circuit 63B via two switching circuits 33A and 33B, respectively. The preliminary arithmetic unit 32 is also connected to the first inverter drive circuit 63A and the second inverter drive circuit 63B via the two switching circuits 33A and 33B, respectively.

  When a limited failure occurs such that only a terminal for outputting a drive instruction to the inverter drive circuit is fixed to the main arithmetic unit 31, two switching is performed by a switching signal from the main arithmetic unit 31 and the preliminary arithmetic unit 32. The circuits 33A and 33B are switched to the preliminary arithmetic unit 32 side. Thereby, the preliminary arithmetic unit 32 controls both the first control system 60A and the second control system 60B. That is, in the example of FIG. 12, both the first control system 60A and the second control system 60B are emergency control systems.

  In the example of FIG. 12, the switching circuit 33 </ b> A connected to the first inverter drive circuit 63 </ b> A performs a switching operation based on a switching signal from the main arithmetic device 31. Then, the switching circuit 33B connected to the second inverter drive circuit 63B performs a switching operation based on the switching signal from the preliminary calculation device 32. In this way, if two or more switching circuits are controlled by separate arithmetic devices, even if any of the arithmetic devices fails, at least one switching circuit is normally operated by a normal arithmetic device. Can be switched. Therefore, at least one control system can be controlled by a normal arithmetic device.

  In the second embodiment, the motor 20 has two sets of coil groups 22A and 22B, and the motor driving device 30 has two control systems 60A and 60B corresponding thereto. However, the motor 20 may have three or more sets of coils, and the motor driving device 30 may have three or more control systems correspondingly.

  That is, when N is generalized as an integer of 2 or more, the motor 20 may include the first coil group to the Nth coil group. In that case, it is only necessary that the motor driving device 30 be provided with a first control system to an Nth control system for supplying a drive current to each coil group individually. In addition, the main arithmetic unit, from the first current command value setting unit to the Nth current command value setting unit, from the first control unit to the Nth control unit, and from the first failure detection unit to the Nth failure detection unit, is normal. Just execute the function. Further, when an arbitrary integer from 1 to N is set to n, the preliminary arithmetic unit, at the time of failure of the main arithmetic unit, the n-th current command of at least one emergency control system included in the first to N-th control systems. The functions of the value setting unit, the nth control unit, and the nth fault detection unit may be executed.

  Further, as in the example of FIG. 12, two or more emergency control systems may be included in the first to Nth control systems. In that case, the electric circuit which comprises a motor drive device may have two or more switching circuits corresponding to each of two or more emergency control systems. If it does so, when a main arithmetic unit fails, operation of a motor can be continued using two or more control systems.

  In the second embodiment, a part of information input / output to / from the second control system is performed via the preliminary calculation device 32. However, a part of the input / output of information with respect to the first control system may be performed via the preliminary calculation device 32. By doing so, the number of terminals of the preliminary arithmetic unit 32 can be further reduced. Further, the motor driving device 30 may be reduced in size by making the number of terminals of the preliminary computing device 32 smaller than the number of terminals of the main computing device 31.

  Moreover, you may apply said motor drive device 30 to apparatuses other than a power steering apparatus. For example, you may drive the motor used for the other site | part of transport equipment with said motor drive device 30. FIG. Moreover, you may drive the motor mounted in apparatuses other than motor vehicles, such as an industrial robot, by said motor drive device 30. FIG.

  Further, the detailed configuration of the motor drive device may be different from the configuration shown in each drawing of the present application. For example, part of the functions of the arithmetic device may be realized by an electric circuit. Moreover, you may combine suitably each element which appeared in said embodiment and modification in the range which does not produce inconsistency.

  The present invention can be used for a motor drive device and an electric power steering device.

DESCRIPTION OF SYMBOLS 1 Electric power steering apparatus 10 Torque sensor 20 Motor 21A, 21B Coil 22A 1st coil group 22B 2nd coil group 23A Neutral point 30 Motor drive unit 31 Arithmetic unit, main arithmetic unit 31A 1st arithmetic unit 31B 2nd arithmetic unit 32 Preliminary computing device 33 switching circuit 33A switching circuit 33B switching circuit 34 semiconductor element 40 power supply source 50 gear box 60A first control system 60B second control system 61A first current command value setting unit 61B second current command value setting unit 61b reserve Second current command value setting unit 62A First feedback control unit 62B Second feedback control unit 62b Preliminary second feedback control unit 63A First inverter drive circuit 63B Second inverter drive circuit 64A First inverter 64B Second inverter 65A First current Shut off Unit 65B second current cut-off unit 66A first current detection circuit 66B second current detection circuit 67A first failure detection unit 67B second failure detection unit 67b preliminary second failure detection unit 68A switching element 69A first shunt resistor 71A, 71B input Signal 72A, 72B Current command value 73A, 73B Drive instruction 74A, 74B PWM signal 75A, 75B Drive current 76A, 76B Detection signal 77A, 77B Detection result 80b Monitoring unit 91 Steering wheel 92 Steering shaft 93 Wheel 311 First power supply circuit 312 First 1 monitoring circuit 321 second power supply circuit 322 second monitoring circuit V0 ground voltage V1 power supply voltage

Claims (8)

A motor driving device for driving a motor,
N is an integer of 2 or more, and any integer from 1 to N is n,
The first control system to supply the drive current individually from the first coil group included in the motor to the Nth coil group, the Nth control system,
The nth control system is
An nth inverter for supplying a driving current to the nth coil group;
An nth current command value setting unit for setting an nth current command value according to an input signal from the outside;
An nth control unit that gives a drive instruction to a drive circuit of the nth inverter based on the nth current command value;
An n-th fault detection unit for detecting a fault in the n-th inverter or the n-th coil group;
Have
A motor drive device that stops or degenerates the operation of the n-th control system when the n-th failure detection unit detects the failure. The motor driving device according to claim 1,
The n-th failure detection unit, when detecting the failure, determines whether or not a degenerate operation is possible in the n-th control system,
A motor drive device that performs a degeneracy operation in the n-th control system when the degeneration operation is possible. The motor drive device according to claim 2,
The motor is a three-phase synchronous motor;
The n-th failure detection unit, when detecting the failure, determines whether or not two phases out of three phases are normal in the n-th control system,
A motor drive device that performs a degeneration operation by two-phase energization in the n-th control system when two of the three phases are normal. The motor drive device according to any one of claims 1 to 3, wherein
The nth control system is:
An n-th current cut-off unit provided on a path of drive current from the n-th inverter to the n-th coil group;
When the n-th failure detecting unit detects the failure, the n-th current interrupting unit interrupts at least a part of the path current. The motor drive device according to any one of claims 1 to 4, wherein
It has one arithmetic device that performs arithmetic processing based on a preset program,
The one arithmetic unit includes the first current command value setting unit to the Nth current command value setting unit, the first control unit to the Nth control unit, and the first failure detection unit to the Nth failure detection. A motor drive device that executes the function of the unit. The motor drive device according to any one of claims 1 to 4, wherein
It has a plurality of arithmetic devices that perform arithmetic processing based on a preset program,
Each of the plurality of arithmetic devices is a motor drive device that executes the functions of one n-th current command value setting unit, one n-th control unit, and one n-th failure detection unit. The motor drive device according to any one of claims 1 to 6, wherein
The nth inverter has an nth shunt resistor,
The n-th failure detection unit detects a failure of the n-th inverter or the n-th coil group based on a shunt current flowing through the n-th shunt resistor. An electric power steering device for assisting a driver's steering,
A torque sensor for detecting torque by steering;
The motor drive device according to any one of claims 1 to 7,
A motor driven by the motor driving device;
Have
The n-th current command value setting unit sets an n-th current command value according to a torque signal input from the torque sensor.

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