JP2009291005A - Motor control apparatus and motor control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the number of flux linkage of a magnet rotor which has a manufacture error. <P>SOLUTION: A control apparatus of a motor, which has a stator coil that generates magnetic field and the magnet rotor that is rotated by the magnetic field and that outputs torque to the steering shaft of a vehicle, has a detection means of the number of flux linkage, which detects the number of the flux linkage based on a voltage generated in the stator coil and the rotational speed of the magnet rotor, when the magnet rotor is rotated interlocking with the steering shaft in a state that a driving voltage is not supplied to the stator coil. Thus, the number of flux linkage of the magnet rotor having the manufacture error can be detected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device for deriving a target drive current supplied to a stator coil for a magnet rotor of a motor to output a predetermined target torque based on the number of flux linkages of the magnet rotor, and in particular, the magnet rotor. The present invention relates to a technique for detecting the number of flux linkages.

  2. Description of the Related Art An electric power steering (hereinafter referred to as EPS) system that is mounted on a vehicle such as an automobile and assists steering by a driver with a motor output is known. A general EPS system includes a torque sensor that detects a steering torque when a driver of a mounted vehicle operates a steering wheel, a motor control device that derives a magnitude of an auxiliary torque corresponding to the steering torque, and a motor An assist motor that outputs an assist torque in response to an instruction signal from the control device is provided, and assists the driver with the assist torque output by the assist motor. Patent Document 1 describes an example of a motor control device used in such an EPS system.

  FIG. 1 shows a configuration example of an EPS system. In this EPS system, when the driver operates the steering wheel 1 and the steering shaft 3 rotates, the torsion bar 4a included in the torque sensor 4 is twisted. The torque sensor 4 generates a voltage signal corresponding to the torque applied to the torsion bar 4a from the torsion degree of the torsion bar 4a and the spring constant of the torsion bar 4a, and uses this voltage signal as a steering torque signal to the motor control device 2. Output. The motor control device 2 derives the magnitude of the auxiliary torque corresponding to the steering torque indicated by the steering torque signal as the target torque, and further derives the drive voltage to be applied to cause the assist motor 8 to output the target torque, A drive voltage is applied to the assist motor 8. The auxiliary torque output by the assist motor 8 according to the drive voltage is transmitted to the pinion shaft 10 through the reduction gear 6 at a predetermined ratio. Then, when the pinion shaft 10 is rotated by the steering torque applied to the steering shaft 3 and the auxiliary torque output from the assist motor, the rack shaft 14 interlocked with the pinion shaft 10 is moved in the axial direction by the rack and pinion mechanism 12. Then, the movement of the rack shaft 14 is transmitted to the steering wheel 17 through the tie rod 15 and the knuckle arm 16, and the steering wheel 17 is steered.

  In the above configuration, the assist motor 8 includes a stator coil that generates a magnetic field by three-phase AC and a field magnet rotor (magnet rotor) that outputs torque by rotating by the magnetic field. Consists of a brushless motor.

  Further, the motor control device 2 is configured around a microcomputer, and derives the magnitude of the auxiliary torque corresponding to the steering torque as a target torque by map data calculation, and the magnet rotor of the assist motor 8 outputs the target torque. A target drive current to be supplied to the stator coil is derived.

  Here, in an EPS system using a brushless assist motor having a stator coil and a magnet rotor, a drive current i supplied to the stator coil of the assist motor, a target torque T, a pole pair number p of the stator coil, a magnet rotor The following relationship holds between the number of flux linkages Φ and the reduction gear ratio Gr of the reduction gear.

i = T / (p · Φ · Gr) Equation (1)
By utilizing this, the motor control device 2 uses the stator coil pole pair number p stored in a ROM (Read Only Memory) or the like inside the device, the linkage flux number Φ of the magnet rotor, and the reduction ratio Gr of the reduction gear 6. The design values of the assist motor 8 and the EPS system are read out, and a calculation for deriving a target drive current corresponding to the target torque is performed based on the equation (1).

The motor control device 2 derives a drive voltage to be applied to the assist motor 8 from the target drive current, and applies the drive voltage to the stator coil of the assist motor.
JP 2007-82315 A

  Since the number of pole pairs of the stator coil and the reduction ratio Gr of the reduction gear 6 used when the motor control device 2 derives the target drive current as described above are values determined by the structure of the EPS system, a manufacturing error occurs. Absent. However, since the number of flux linkages Φ of the magnet rotor is a value related to the physical properties of the magnet rotor, a manufacturing error with respect to the design value may occur. Then, when the number of flux linkages of the magnet rotor actually has a manufacturing error, if the target drive current is derived using the design value and the drive voltage corresponding to the target drive current is derived, the desired target torque is I can't get it. Further, depending on the size of the manufacturing error, there is a risk that the control will fail.

  Accordingly, an object of the present invention made in view of such a problem is to detect the number of interlinkage magnetic fluxes including a manufacturing error of a magnet rotor, and to use this to derive a target drive current and its control It is to provide a method.

  In order to achieve the above object, a motor control device according to a first aspect of the present invention is a motor having a stator coil that generates a magnetic field and a magnet rotor that rotates by the magnetic field and outputs torque to a steering shaft of a vehicle. A control device for deriving a target drive current supplied to the stator coil for the magnet rotor to output a predetermined target torque based on the number of flux linkages of the magnet rotor; and Drive voltage deriving means for deriving a drive voltage to be applied to the stator coil in order to supply a target drive current to the stator coil.

  The motor control device is configured to generate a voltage generated in the stator coil and a rotation speed of the magnet rotor when the magnet rotor rotates in conjunction with the steering shaft without supplying a driving voltage to the stator coil. And further comprising a linkage flux number detecting means for detecting the linkage flux number.

  According to the above aspect, by rotating the steering shaft in a state where no driving voltage is supplied to the stator coil, the linkage flux number detecting means is operated when the magnet rotor rotates in conjunction with the rotation of the steering shaft. Since the number of flux linkages is detected based on the voltage generated in the stator coil and the rotational speed of the magnet rotor, the number of flux linkages including manufacturing errors can be detected. Therefore, the target drive current can be derived using the detected number of flux linkages, and the target torque can be output to the magnet rotor by applying the drive voltage for supplying the target drive current to the stator coil.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

  FIG. 2 is a diagram illustrating a configuration of the assist motor and the motor control device that controls the assist motor in the present embodiment. The assist motor and the motor control device shown in FIG. 2 are applied to the EPS system shown in FIG.

  The assist motor 8 is a three-phase alternating current brushless motor as an example, and a stator coil that generates a magnetic field by supplying three-phase alternating currents of U phase, V phase, and W phase that are phase shifted by 2π / 3 each. 8b and a magnet rotor 8c that rotates by being attracted and repelled by the magnetic field generated by the stator coil 8b. The magnet rotor 8c is interlocked with the steering shaft 3 shown in FIG. 1, and torque is output to the steering shaft 3 when the magnet rotor 8c rotates. The assist motor 8 is provided with a rotation angle sensor 8 a that detects the rotation angle of the magnet rotor 8 c and outputs a rotation angle signal, and the rotation angle signal is taken into the motor control device 2.

  The motor control device 2 includes a motor drive circuit 22 that applies a drive voltage to the stator coil 8 b of the assist motor 8, and a control unit 40 that derives the drive voltage based on a steering torque signal input from the torque sensor 4.

  The motor drive circuit 22 uses, as an example, a 6-channel MOSFET as an active element, and inverts a DC voltage supplied from a vehicle-mounted power source (not shown) by an inverter, so that a U voltage corresponding to a drive voltage instruction signal supplied from the control unit 40 is obtained. -Generate a three-phase AC voltage in the V-W coordinate system. This AC voltage is applied to the stator coil 8b as a drive voltage. Note that the switch circuit 30 described in detail later is in a closed state at this time, and the three-phase drive voltage energization lines are connected.

  In addition, a current sensor 26 that detects a drive current supplied to the stator coil 8b when a drive voltage is applied is connected to each of the U-phase, V-phase, and W-phase energization lines of the motor drive circuit 22. The detected drive current (hereinafter referred to as detected drive current) is taken into the control unit 40 and used for drive voltage feedback control by the control unit 40.

  For example, the control unit 40 includes a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). Each of the following means included in the control unit 40 is configured by a CPU that operates using the RAM as a work area according to a program stored in the ROM.

  The target torque deriving means 42 receives the steering torque signal from the torque sensor 4 and maps the magnitude of the auxiliary torque corresponding to the steering torque indicated by the steering torque signal as the target torque to be output by the magnet rotor 8c of the assist motor 8. Derived by data calculation. Further, when deriving the target torque, the target torque deriving means 42 may derive the target torque based on the speed of the mounted vehicle and the steering torque. In this case, the motor control device 2 is connected to another in-vehicle control device 80 via an in-vehicle LAN (Local Area Network), and the target torque deriving means 42 transmits a vehicle speed signal transmitted from the in-vehicle control device 80 via the network driver 70. The vehicle speed is detected from the vehicle speed signal.

  The target drive current deriving unit 44 executes a calculation for deriving a target drive current to be supplied to the stator coil 8b in order for the magnet rotor 8c to output a target torque. The target drive current is handled in the DQ coordinate system, which is a two-phase rotational coordinate system that rotates at an electrical angle with respect to the UVW coordinate system. Specifically, the target drive current deriving unit 44 sets the D axis target drive current to 0 amperes, and executes a calculation for deriving the Q axis target drive current. At this time, the target drive current deriving means 44 is connected to the pole pair number p of the stator coil 8b, the magnet rotor 8c from the storage unit 72 formed of a rewritable nonvolatile storage medium such as an EEPROM (Electronically Erasable and Programmable Read Only Memory). The number of interlinkage magnetic fluxes Φ and the gear ratio Gr of the reduction gear 6 in the EPS system are read out, and the Q-axis target drive current iq corresponding to the target torque T is derived as follows by using the above equation (1). Perform the operation.

iq = T / (p · Φ · Gr)
Next, the drive voltage deriving unit 46 derives the drive voltage in the UVW coordinate system from the target drive current in the DQ coordinate system. At this time, the drive voltage deriving unit 46 performs feedback control of the drive voltage based on the detected drive current detected by the current sensor 26. At this time, the rotation speed detection means 60 acquires a rotation angle signal from the rotation angle sensor 8a and derives the rotation angle θ of the magnet rotor 8c. Further, the rotational speed detection means 60 derives the rotational speed ω of the magnet rotor 8c from the time change of the rotational angle θ. Then, the rotation angle detection unit 60 passes the rotation angle θ and the rotation speed ω to the drive voltage deriving unit 46.

  Here, the detailed configuration and operation of the drive voltage deriving means 46 will be described with reference to FIG. First, the current coordinate conversion means 58 converts the detection drive current in the UVW coordinate system detected by the current sensor 26 into the detection drive current in the DQ coordinate system using the following coordinate conversion formula. Here, the rotation angle θ of the magnet rotor 8c is used as the electrical angle.

次に、電流偏差導出手段４８は、Ｄ−Ｑ座標系における目標駆動電流と検知駆動電流の偏差を算出する。そして、駆動電圧導出手段５０は、駆動電流の偏差に基づき比例積分制御を実行して、偏差がゼロになるようなＤ−Ｑ座標系での目標駆動電流を導出する。そして、駆動電圧導出手段５０は次のモータ電圧方程式により、Ｄ−Ｑ座標系での目標駆動電流を目標駆動電圧へ変換する。ここでは、マグネットロータ８ｃの回転速度ωが電気角速度として用いられる。

Next, the current deviation deriving unit 48 calculates a deviation between the target drive current and the detected drive current in the DQ coordinate system. Then, the drive voltage deriving unit 50 performs proportional-integral control based on the deviation of the drive current, and derives the target drive current in the DQ coordinate system such that the deviation becomes zero. Then, the drive voltage deriving means 50 converts the target drive current in the DQ coordinate system into the target drive voltage according to the following motor voltage equation. Here, the rotational speed ω of the magnet rotor 8c is used as the electrical angular speed.

次に、駆動電圧変換手段５２は、次の座標変換式によりＤ−Ｑ座標系の駆動電圧をＵ−Ｖ−Ｗ座標系の駆動電圧に変換する。

Next, the drive voltage conversion means 52 converts the drive voltage of the DQ coordinate system into the drive voltage of the UVW coordinate system by the following coordinate conversion formula.

そして、ＰＷＭ手段５４は、２π／３ずつ位相がずれたＵ−Ｖ−Ｗ座標系の交流電圧を直流電圧で形成するようなデューティ比を導出し、かかるデューティ比を示すＰＷＭ信号を駆動電圧指示信号としてモータ駆動回路２２に出力する。

Then, the PWM means 54 derives a duty ratio that forms an AC voltage in the UVW coordinate system whose phase is shifted by 2π / 3 by a DC voltage, and outputs a PWM signal indicating the duty ratio as a drive voltage instruction. The signal is output to the motor drive circuit 22 as a signal.

  Here, the operation procedure of the control unit 40 configured as described above is shown in the flowchart of FIG. When the steering torque signal is input from the torque sensor 4 (S100), the target torque deriving means 42 derives the target torque by map data calculation (S102). Next, the target drive current deriving unit 44 performs a calculation for deriving the Q axis target drive current (S104). Then, the rotational speed detection means 60 derives the rotational angle and rotational speed of the magnet rotor 8c (S106).

  Next, the current coordinate conversion means 58 converts the detection drive current of the UVW coordinate system into the detection drive current of the DQ coordinate system (S108). Then, the current deviation deriving unit 48 calculates the deviation between the target drive current and the detected drive current in the DQ coordinate system (S110). Then, the drive voltage deriving unit 50 performs proportional-integral control based on the deviation of the drive current, derives a target drive current in the DQ coordinate system such that the deviation becomes zero, and the drive voltage deriving unit 50 The target drive voltage is converted (S112). Then, the drive voltage conversion means 52 converts the drive voltage in the DQ coordinate system into the drive voltage in the UVVW coordinate system (S114), and the PWM means 54 converts the AC voltage in the UVW coordinate system. Is derived (S116), and a PWM signal indicating the duty ratio is output to the motor drive circuit 22 as a drive voltage instruction signal (S118).

  In the above operation, design values are stored in advance in the storage unit 72 for the pole pair number p of the stator coil 8b and the gear ratio Gr of the reduction gear 6, which are coefficients used by the target drive current deriving means 44 when deriving the target drive current. Is done. However, since the interlinkage magnetic flux number Φ of the magnet rotor 8c may include a manufacturing error, if the target drive current is detected using the design value, the intended target torque may not be obtained. Therefore, in order to avoid such a situation, the motor control device according to the present embodiment detects the actual number of flux linkages of the magnet rotor 8c and stores it in the storage unit 72, and is used when deriving the target drive current. Set as a coefficient.

  Returning to FIG. 2, as a configuration for setting the number of interlinkage magnetic fluxes, the motor control device 2 includes a switch circuit 30 for opening and closing a drive voltage line from the motor drive circuit 22 to the stator coil 8b, and generation of the stator coil 8b. And a voltage sensor 32 for detecting a voltage. The voltage sensor 32 detects the generated voltage of the stator coil 8b in a state where the energization line to the stator coil is opened by the switch circuit 30 as will be described later, so that the U phase and V phase with respect to the ground potential of the control unit 40 are detected. Instead of detecting the voltage value for each W phase, the potential difference between any two phases is detected. Therefore, the voltage sensor 32 is configured by a differential amplifier circuit using an operational amplifier or the like.

  Further, the control unit 40 detects the number of interlinkage magnetic fluxes Φ based on the generated voltage of the stator coil 8b and the rotational speed of the magnet rotor 8c when the magnet rotor 8c rotates without supplying a drive voltage to the stator coil 8b. The magnetic flux linkage number detecting means 66 is provided.

  The operation in which the motor control device 2 configured as described above sets the number of flux linkages will be described.

  The setting of the number of flux linkages Φ is executed in an inspection process or the like when the EPS system is mounted on the vehicle. In this process, an input device 82 outside the vehicle constituted by a personal computer or the like is connected to the in-vehicle LAN. The motor control device 2 is connected to the input device 82 via the network driver 70 and receives a setting instruction signal from the input device 82. Then, the linkage flux number detecting means 66 opens the switch circuit 30 in response to the setting instruction signal. As a result, the energization path of the stator coil 8b is eliminated, so that the drive current supplied to the stator coil 8b is held at 0 A (ampere).

  In this state, for example, when the setting operator rotates the steering wheel 1 of the EPS system from the outside, the magnet rotor 8 c rotates in conjunction with the rotation of the steering shaft 3 that is the “steering shaft”. Then, since the magnetic flux generated by the magnet rotor 8c rotates, an induced voltage is generated in the stator coil 8b by electromagnetic induction. The voltage sensor 32 detects the voltage generated by the stator coil 8 b and passes it to the linkage flux number detecting means 66. On the other hand, the rotation speed detection means 60 detects the rotation speed ω of the magnet rotor 8c from the time change in the discrete value of the rotation angle of the magnet rotor 8c.

  Here, according to the motor voltage equation showing the relationship between the drive current and the drive voltage in the DQ coordinate system, the relationship of the above-described formula (2) is established between the drive current and the drive voltage of the stator coil 8b.

At this time, since the drive current of the stator coil 8b is 0 amperes, id = 0 and iq = 0 in the above equation (2), the following equation is derived.
Vq = Φ · ω Equation (3)
In order to detect the number of flux linkages of the magnet rotor 8c using this fact, the flux linkage number detecting means 66 first generates the generated voltage Vq in the DQ coordinate system from the generated voltage in the UVW coordinate system. Is derived. At this time, the linkage flux number detecting means 66 derives the effective value of the generated voltage between the U phase and the V phase obtained by the following equation as the generated voltage Vq of the Q axis.

そして、鎖交磁束数検出手段６６は、上記の発生電圧Ｖｑと回転速度ωを用いて上述の式（３）を鎖交磁束数Φについて解く演算を実行し、鎖交磁束数Φ（＝Ｖｑ／ω）を検出する。

Then, the linkage flux number detecting means 66 performs an operation for solving the above equation (3) for the linkage flux number Φ using the generated voltage Vq and the rotational speed ω, and the linkage flux number Φ (= Vq). / Ω) is detected.

  Thus, according to the present embodiment, even when there is a manufacturing error in the magnet rotor 8c of the assist motor 8, the actual number of flux linkages including the manufacturing error can be detected. The interlinkage magnetic flux number detection means 66 stores the detected interlinkage magnetic flux number (hereinafter referred to as the detected interlinkage magnetic flux number to distinguish it from the design value) in the storage unit 72, and is used for deriving the target drive current. Set as a coefficient. As described above, once the number of detected flux linkages is set as a coefficient, the target drive current can be derived using the detected number of flux linkages, and therefore the desired auxiliary torque can be output to the magnet rotor 8c. it can.

  In the present embodiment, the magnet rotor 8c is rotated to detect the voltage generated by the stator coil 8b and the rotation speed of the magnet rotor 8c, and the number of interlinkage magnetic fluxes is obtained based on the detected voltage. There is no need to provide a special inspection device for detecting the number of magnetic fluxes. Since the operator can rotate the magnet rotor 8c by steering the steering wheel 1, it is not necessary to additionally provide a drive mechanism for rotating the magnet rotor 8c, and the diameter is large. By rotating the steering wheel 1, uneven rotation of the magnet rotor 8c having a small diameter can be reduced. Furthermore, according to the present embodiment, the number of interlinkage magnetic fluxes can be detected even after the EPS system is mounted on a vehicle, so that the inspection process time can be saved.

  Here, an operation procedure when the motor control device 2 detects the number of flux linkages and sets it as a coefficient for deriving the target drive current will be described with reference to FIGS.

  FIG. 5 is a flowchart showing the procedure of the inspection process as the entire EPS system. When the ignition switch of the vehicle is turned on by the operator (S2) and a setting instruction signal is input from the input device (S4), the inspection process is started. In the inspection process, first, the midpoint correction of the torque sensor 4 is executed (S6). When the midpoint correction ends normally (YES in S8), the correction of the rotation angle sensor 8a is then executed (S10). When the correction of the rotation angle sensor 8a is normally completed (YES in S12), the number of flux linkages is set (S14). When the setting of the number of flux linkages ends normally (YES in S16), the inspection process ends.

  FIG. 6 is a flowchart for explaining an operation procedure in which the motor control device 2 sets the number of flux linkages. This corresponds to the subroutine of step S14 shown in FIG. In response to the input of the correction instruction signal in step S4 of FIG. 5, the flux linkage number detecting means 66 first opens the switch circuit 30 (S30). Here, the linkage flux number detecting means 66 transmits a signal indicating, for example, that the switch circuit 30 is opened to the input device, and a procedure for displaying the opening of the switch circuit 30 on the display unit attached to the input device. May be added. Then, the operator steers the steering wheel (S32).

  Then, the rotation speed detection means 60 detects the rotation angle of the magnet rotor 8c (S34), and detects the rotation speed from the time variation of the discrete value (S36). Then, the linkage flux number detecting means 66 detects the generated voltage of the stator coil 8b (S38) and derives the generated voltage of the Q axis (S40). The interlinkage magnetic flux number detecting means 66 detects the interlinkage magnetic flux number of the magnet rotor 8c from the rotation speed of the magnet rotor 8c and the generated voltage of the Q axis (S42).

  Then, the linkage flux number detecting means 66 determines whether or not the detected linkage flux number is within an allowable range (S44). For example, the average value and the standard deviation σ of the number of flux linkages of the magnet rotor 8c in a predetermined production lot are stored in the storage unit 72 in advance, and if the detected number of flux linkages is the average value ± 3σ, it is within the allowable range. It can be. When the determination result is “YES”, the number of detected flux linkages is stored in the storage unit 72 (S46) so as to be set as a coefficient for deriving the target drive current, and the setting process of the number of flux linkages is normal. The process ends (S48). On the other hand, when the determination result in step S44 is “NO”, the process ends abnormally (S50).

  According to such a procedure, the actual number of flux linkages including manufacturing errors can be detected, and the detected number of flux linkages can be set as a coefficient for deriving the target drive current. Therefore, by using the detected number of interlinkage magnetic fluxes, a target drive current is derived so that the magnet rotor 8c of the assist motor actually incorporated in the EPS system can output the desired auxiliary torque, and the drive voltage based on this is derived. Can be derived.

  In addition, according to the motor control device 2 in the present embodiment, it is possible to execute fail-safe processing when an abnormality occurs in the storage unit 72 and data on the number of detected flux linkages once stored is destroyed.

  FIG. 7 is a diagram illustrating a configuration example of the motor control device 2 that executes fail-safe processing. In addition to the configuration example of FIG. 2, a storage unit 73 that is a ROM of the control unit 40 is illustrated. The storage unit 73 stores a design value of the number of flux linkages in advance.

  In such a configuration, the interlinkage magnetic flux number detecting means 66 mirrors the data when storing the detected interlinkage magnetic flux number Φ in the storage unit 72, and stores the data in different storage areas 72 a and 72 b in the storage unit 72. , Φb.

  Then, the target drive current deriving unit 44 obtains the detected flux linkage numbers Φa and Φb mirrored from the storage areas 72a and 72b of the storage unit 72, for example, when the ignition is turned on and the motor control device 2 is started. And collate the two data. If the two data match, the storage unit 72 confirms that it is operating normally. In that case, the target drive current deriving means 44 performs a calculation for deriving the target drive current using the detected number of flux linkages Φ. On the other hand, when the two data do not match, it is determined that an abnormality has occurred in the storage unit 72 and, as a result, the data on the number of detected flux linkages has been destroyed. In this case, the target drive current deriving unit 44 reads and uses the design value Φ1 of the number of flux linkages stored in advance in the storage unit 73 different from the storage unit 72. By doing so, it is possible to execute safer control than performing control based on at least the destroyed data.

  FIG. 8 is a flowchart showing an operation procedure of the motor control device when fail-safe processing is performed. The procedure of FIG. 8 is executed when the ignition switch of a vehicle on which the motor control device 2 is mounted is turned on and the motor control device 2 is activated.

  The target drive current deriving unit 44 reads the mirrored flux linkage number data stored in the storage areas 72a and 72b of the storage unit 72 (S60) and collates the two data (S62). If the data match (YES in S64), it is determined that the number of flux linkages is normal, and the process ends. In this case, the state where the detected number of flux linkages is set as a coefficient for deriving the target drive current is maintained. On the other hand, when the data do not match (NO in S64), the target drive current deriving unit 44 reads the design value of the number of flux linkages from the storage unit 73 and uses it as a coefficient for deriving the target drive current (S66). .

  According to such a procedure, even when the data stored in the storage unit 72 is abnormal, the motor control device 2 can execute the control based on the design value. Safe control can be executed.

  As described above, according to this embodiment, even if there is a manufacturing error in the magnet rotor of the assist motor, the actual number of flux linkages including the manufacturing error can be detected. Therefore, the target drive current can be derived using the detected number of flux linkages, and the target torque can be output to the magnet rotor by applying a drive voltage that supplies the target drive current to the stator coil. it can.

It is a figure which shows the structural example of a general EPS system. It is a figure which shows the structure of the assist motor in this embodiment, and the motor control apparatus which controls this. A detailed configuration and operation of the drive voltage deriving means 46 will be described. FIG. 4 is a flowchart illustrating an operation procedure of a control unit 40. It is a flowchart figure which shows the procedure of the inspection process as the whole EPS system. It is a flowchart explaining the operation | movement procedure in which the motor control apparatus 2 detects and sets the number of flux linkages. It is a figure which shows the structural example of the motor control apparatus 2 which performs a fail safe process. It is a flowchart figure which shows the operation | movement procedure of a motor control apparatus when performing a fail safe process.

Explanation of symbols

1: steering wheel, 2: motor control device, 3: steering shaft, 8: assist motor,
8b: Stator coil, 8c: Magnet rotor, 44: Target drive current deriving means, 46: Drive voltage deriving means, 66: Linkage magnetic flux number detecting means

Claims (4)

A motor control device having a stator coil that generates a magnetic field and a magnet rotor that rotates by the magnetic field and outputs torque to a steering shaft of a vehicle,
Target drive current deriving means for deriving a target drive current supplied to the stator coil for the magnet rotor to output a predetermined target torque based on the number of flux linkages of the magnet rotor;
Drive voltage deriving means for deriving a drive voltage to be applied to the stator coil in order to supply the target drive current to the stator coil;
When the magnet rotor rotates in conjunction with the steering shaft in a state where no driving voltage is supplied to the stator coil, the linkage flux is generated based on a generated voltage generated in the stator coil and a rotation speed of the magnet rotor. A control device further comprising linkage flux number detecting means for detecting the number. In claim 1,
The linkage flux number detecting means derives a generated voltage of a two-phase coordinate system from the generated voltage of three-phase alternating current, and uses the motor voltage equation from the derived generated voltage and the rotation speed to calculate the linkage flux number. A control device for detecting In claim 1,
A first storage unit in which the number of designed flux linkages is stored; and a second storage unit in which the detected number of detected flux linkages is stored;
The interlinkage magnetic flux number detecting means stores a plurality of data of the detected interlinkage magnetic flux number in the second storage unit,
The target drive current deriving means uses the detected number of flux linkages when the plurality of data of the detected number of flux linkages read from the second storage unit match, and the plurality of data matches. If not, the control device derives the target drive current using the designed number of flux linkages read from the first storage unit. A stator rotor and a magnet rotor that rotates by a magnetic field generated by the stator coil and outputs a predetermined target torque to a vehicle steering shaft, and a target drive current is derived based on the number of flux linkages of the magnet rotor, A motor control method in which a drive voltage for supplying the target drive current to the stator coil is applied to the stator coil,
Rotating the steering shaft without supplying a driving voltage to the stator coil;
Detecting the number of flux linkages based on the generated voltage generated in the stator coil when the magnet rotor rotates in conjunction with the rotation of the steering shaft and the rotational speed of the magnet rotor. Characteristic control method.

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