JP2019170155A - Three-phase synchronous motor control device and drive device, and electric power steering device - Google Patents

Abstract

To provide a three-phase synchronous motor control device and a drive device capable of improving reliability of a rotational position detector of the three-phase synchronous motor without increasing a cost of the rotational position detector and an electric power steering device.SOLUTION: By comparing outputs of two rotational position detectors 41, 42, abnormalities of the rotational position detectors 41, 42 are detected. Then, a rotational position detector that is abnormal is identified by a rotational position estimating means 2. Using an output θ of the normal rotational position detector of either a first or second, drive of a three-phase synchronous motor 4 is controlled.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device and a drive device for a three-phase synchronous motor, and an electric power steering device.

  Small and highly efficient three-phase synchronous motors are widely used in various fields such as industry, home appliances, and automobiles. However, in a three-phase synchronous motor, in general, the rotational position of a rotor provided with a magnet is detected by a magnetic detection element such as a Hall IC, and the armature coil on the stator side is sequentially excited based on the detection result. Is rotating. In addition, by using a resolver, an encoder, a GMR sensor, or the like that is a precise rotational position detector, driving with a sine wave current can be realized, and vibrations such as torque ripple and noise can be reduced.

  However, if this rotational position detector fails, the three-phase synchronous motor cannot immediately rotate. The same applies to the case where a resolver, an encoder, or a GMR sensor is used as the rotational position detector. As described above, the failure of the rotational position detector causes a malfunction or abnormal operation in a driving device for a three-phase synchronous motor such as an electric power steering, and therefore, improvement has been demanded.

  The invention described in Patent Document 1 has rotational position estimation means for estimating the position from the voltage and current of the three-phase synchronous motor in addition to the rotational position detector when the rotational position detector fails. By using this rotational position estimating means as an alternative to the output of the rotational position detector, the three-phase synchronous motor can be stably driven even when the rotational position detector is out of order.

JP 2010-22196 A

  As in Patent Document 1, when the rotational position detector is used instead of the rotational position detector when the rotational position detector fails, the three-phase synchronous motor can be continuously driven. However, a difference occurs between the actual rotor position and the estimated rotor position, and the output of the three-phase synchronous motor decreases. Therefore, it is possible to use two rotational position detectors in the event of a failure of one rotational position detector by using two rotational position detectors such as a resolver, encoder, and GMR sensor with high rotational position detection accuracy. It is done. However, since this method cannot determine which of the two rotational position detectors is faulty, it is necessary to use three or more rotational position detectors, and increasing the cost of the rotational position detector is a problem. It was.

  An object of the present invention is to provide a control device and a drive device for a three-phase synchronous motor, and an electric power steering device that improve the reliability of the rotational position detector of the three-phase synchronous motor without increasing the cost of the rotational position detector. It is to provide.

  The control device for a three-phase synchronous motor according to the present invention is based on the signals from the first rotational position detector and the second rotational position detector that detect the rotor position of the three-phase synchronous motor. And a rotational position estimating means for computing a rotor position based on a neutral point potential or a virtual neutral point potential of the three-phase synchronous motor, and the first rotational position detector When the output signal is different from the output signal of the second rotational position detector, the output signal of the first rotational position detector and the second signal are based on the rotor position calculated by the rotational position estimating means. One of the output signals of the rotational position detector is selected, and the three-phase synchronous motor is controlled.

  A drive device for a three-phase synchronous motor according to the present invention includes a control device for a three-phase synchronous motor according to the present invention, and a three-phase synchronous motor controlled by the control device.

  An electric power steering device according to the present invention steers a tire by a three-phase synchronous motor control device according to the present invention, a three-phase synchronous motor controlled by the control device, and an output torque of the three-phase synchronous motor. A steering mechanism.

  According to the three-phase synchronous motor control device and drive device, and the electric power steering device according to a preferred embodiment of the present invention, the rotational position estimation means determines which of the two rotational position detectors is faulty. To do. By doing so, it is possible to operate without reducing the output of the three-phase synchronous motor due to the failure of one of the two rotational position detectors.

  Other objects and features of the present invention will be made clear in the embodiments described below.

It is a block diagram of the drive device of the three-phase synchronous motor which concerns on 1st Embodiment. This is processing of the detection position determination means 1. It is the block diagram which showed the position estimation means 2 based on a neutral point electric potential. It is a block diagram of the drive device of the three-phase synchronous motor which used the shunt current detection part 36 for electric current detection. It is a block diagram of the electric power steering device which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the drive device of the three-phase synchronous motor in connection with 2nd Embodiment. This is processing of the detection position selection means 9.

  Hereinafter, an embodiment of a power conversion device according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is described about the same element and the overlapping description is abbreviate | omitted.

(First embodiment)
A first embodiment of a three-phase synchronous motor driving apparatus according to the present invention will be described with reference to FIGS.

  FIG. 1 shows the configuration of a drive device 6 for a three-phase synchronous motor. The three-phase synchronous motor drive device 6 is intended to drive the three-phase synchronous motor 4. A driving device 6 for a three-phase synchronous motor according to the present embodiment is configured to include a detection position determination means 1, a rotational position estimation means 2, a power converter 3, a three-phase synchronous motor 4 to be driven, and a control unit 5. The

  A feature of the drive device according to the present embodiment is that the rotational position estimating means 2 determines a failure (abnormality) of the first rotational position detector 41 and the second rotational position detector 42 and correctly outputs the rotational position. It is to drive the three-phase synchronous motor 4 using a detector.

  As shown in FIG. 1, the detection position determination means 1 receives the output θ1 of the first rotational position detector 41, the output θ2 of the second rotational position detector 42, and the output θ3 of the rotational position estimation means 2. The And the detection position determination means 1 outputs rotation position (theta).

  FIG. 2 is a diagram illustrating a processing flow of the detection position determination unit 1. The detection position determination means 1 first determines whether θ1 and θ2 that are the outputs of the two rotational position detectors are substantially the same. When the outputs are substantially matched, θ1 is used. In the present embodiment, θ1 is used, but a configuration using θ2 may be used.

  When θ1 and θ2 are different, it can be determined that either the rotational position detector 41 or the rotational position detector 42 is out of order. However, it cannot be determined which of the rotational position detector 41 and the rotational position detector 42 is out of order.

  Therefore, the output θ3 of the rotational position estimating means 2 is used to determine which is outputting correctly. First, it is determined whether θ1 and θ3 are substantially the same. If the outputs substantially match, it is determined that θ1 is an output from a normal rotational position detector, and θ1 is used. On the other hand, if the outputs of θ1 and θ3 are different, it is determined whether θ2 and θ3 are substantially the same. If the outputs substantially match, it is determined that θ2 is an output from a normal rotational position detector, and θ2 is used. If θ2 and θ3 are different, θ3 is used.

  The comparison targets θ1, θ2, and θ3 are corrected at the same time by correcting the three positions by correcting the detection timing of the rotational position detector. By doing in this way, since the rotation position at the same timing can be detected appropriately, it is possible to prevent erroneous detection of a failure of the rotation position detector when comparing the rotation positions.

  By configuring the detection position determination means 1 as shown in FIG. 2, even if the first rotational position detector 41 or the second rotational position detector 42 fails, a normal rotational position detector can be used. It is possible to select and output the torque of the three-phase synchronous motor similar to that in the normal state. Furthermore, even if both the first rotational position detector 41 and the second rotational position detector 42 fail, the rotational position estimation means 2 is used to maintain the drive of the three-phase synchronous motor. Therefore, redundancy can be ensured.

  FIG. 3 shows the configuration of the rotational position estimating means 2. The rotational position estimation means 2 estimates the rotational position estimated value θ3 from the virtual neutral point Vn. There are known techniques for estimating the rotational position estimation value θ3 from the detected virtual neutral point Vn at this time, and one of them will be introduced. The rotational position estimation means 2 includes a neutral point potential detection unit 21, a sample / hold unit 22, and a rotational position estimation unit 23.

  The neutral point potential detector 21 detects a virtual neutral point potential Vn0 according to the pulse width modulation signal output from the pulse width modulation signal output means 33. At this time, there is a known technique for detecting the virtual neutral point potential Vn0 from the three-phase synchronous motor 4, and it is omitted because it is not a main part of the present invention.

  The sample / hold unit 22 is an A / D converter for sampling and quantizing the analog signal output of the neutral point potential detection unit 21. The sample / hold unit 22 samples this Vn0 in synchronization with the pulse width modulation signal output from the pulse width modulation signal output means 33. The sample / hold unit 22 outputs the sampled result (Vn0h) to the rotational position estimation unit 23 as a digital signal.

  The rotational position estimation unit 23 calculates an estimated value θ3 of the rotational position of the three-phase synchronous motor 4 based on the neutral point potential sampled by the sample / hold unit 22. This estimation result is output as the output θ3 of the rotational position estimation means 2.

  A feature of the rotational position estimating means 2 is that torque can be produced when the rotational speed of the three-phase synchronous motor is zero. As the rotational position estimating means 2, in this embodiment, a means for estimating the rotational position estimated value θ 3 from the virtual neutral point Vn has been introduced. There is known a method of using one of them, and any one of these methods may be used. Further, instead of the virtual neutral point, the three-phase winding connection point (neutral point) may be directly pulled out and detected. Even when the three-phase synchronous motor 4 is stopped, the rotational position estimating means 2 can detect the rotational position and output torque.

  Further, the abnormality of the first rotational position detector 41 and the second rotational position detector 42 is detected by comparing the output θ3 of the rotational position estimating means 2 with θ1 and θ2. Thereby, the three-phase synchronous motor 4 can be started from the stopped state using the output θ3 of the normal rotational position estimating means 2.

  Returning to FIG. The control unit 5 generates a pulse width modulation signal from the output θ of the detection position determination unit 1. The power converter 3 applies a voltage to the three-phase synchronous motor 4 based on the pulse width modulation signal output from the control unit 5. The power converter 3 includes a DC power supply 31, a power conversion circuit 32, a pulse width modulation signal output means 33, a virtual neutral point potential detection circuit 34, a three-phase current detector 35, and a shunt current detector 36.

  The DC power supply 31 is a DC power supply that supplies current to the power conversion circuit 32. The power conversion circuit 32 is a power conversion circuit configured by six switching elements Sup to Swn. The pulse width modulation signal output means 33 is a driver that inputs the pulse width modulation signal output from the control unit 2 to the power converter 32. The neutral point potential detector 34 detects a virtual neutral point Vn used for the rotational position estimating means. Instead of the virtual neutral point Vn, the neutral point potential of the three-phase synchronous motor 4 may be directly detected. The three-phase current detector 35 is a current detector that detects three-phase currents Iu, Iv, and Iw flowing through the three-phase synchronous motor 4. As for the current detection of the three-phase synchronous motor 4, it is desirable to directly detect the three-phase current supplied from the power conversion circuit 32 to the three-phase synchronous motor 4 like the current detector 35. However, as shown in FIG. The currents Iu, Iv, and Iw in which the DC current Idc flowing through the resistor 36 is detected and the three-phase current is reproduced may be used. There are known techniques regarding a method for reproducing the three-phase currents Iu, Iv, and Iw from the direct current Idc, and they are omitted because they are not the main part of the present invention.

  According to the drive device for a three-phase synchronous motor according to the present embodiment described above, the rotational position estimating means determines which of the two rotational position detectors is malfunctioning. By doing so, even if one of the two rotational position detectors fails, the operation can be continued without lowering the output of the three-phase synchronous motor. Since the rotational position estimating means as shown in the present embodiment can be realized without adding hardware such as a rotational position detector, the three-phase synchronous motor can be realized without increasing the cost of the rotational position detector. The reliability of the rotational position detector can be improved.

(Second Embodiment)
A second embodiment of the electric power steering according to the present invention will be described with reference to FIGS.

  FIG. 5 shows the configuration of the electric power steering apparatus 8. When the driver operates the steering wheel 81, the torque sensor 82 detects the rotational torque of the steering wheel 81. Torque detected by the torque sensor 82 is input to the driving device 6 and the three-phase synchronous motor 4 outputs torque based on a command corresponding to the torque. The output torque of the three-phase synchronous motor 4 assists the steering force via the steering assist mechanism 83 and is output to the steering mechanism 84. Then, the tire 85 is steered by the steering mechanism 84.

  FIG. 6 shows the configuration of the drive device 6 for a three-phase synchronous motor according to the present embodiment. In this embodiment, it has the 1st rotation position estimation means 2 and the 2nd rotation position estimation means 2 as a rotation position estimation means. The second embodiment is different from the first embodiment in that the second rotational position estimating means 7 is provided.

  The first rotational position estimating means 2 and the second rotational position estimating means 7 include a method based on the virtual neutral point Vn introduced in the first embodiment, a method based on the magnetic saturation electromotive voltage, and a three-phase synchronous motor. Any two of the methods using a saliency of 4 may be used. The feature of these three rotational position estimating means is that the drive control of the three-phase synchronous motor is possible even when the rotational speed of the three-phase synchronous motor is 0, and torque can be output. In the electric power steering apparatus provided with such a rotational position estimating means, torque can be output even when the rotational speed of the three-phase synchronous motor is 0. For example, even when the tire of the vehicle runs on a step, the handle of the driver Can be assisted.

  From the above characteristics, the first rotational position estimation means 2 can estimate the rotational position even when the three-phase synchronous motor 4 is stopped. Therefore, the first rotational position is detected by comparing θ3 with θ1 and θ2. The abnormality of the detector 41 and the second rotational position detector 42 can be detected. Further, even when the speed of the automobile is equal to or lower than the predetermined speed and the three-phase synchronous motor 4 is stopped, the first rotational position estimating means 2 can estimate the rotational position. Therefore, by comparing θ3 with θ1 and θ2. The abnormality of the first rotational position detector 41 and the second rotational position detector 42 can be detected.

  Even when the rotational speed of the three-phase synchronous motor 4 is 0 and the vehicle is below a predetermined speed, the first rotational position detection is performed by comparing the output θ3 of the first rotational position estimating means 2 with θ1 and θ2. By detecting an abnormality in the detector 41 and the second rotational position detector 42, the three-phase synchronous motor 4 can be continuously driven and the steering force can be assisted using the normal output θ3 of the first rotational position estimating means 2. .

  FIG. 7 shows the processing of the detection position selection means 9 which is a feature of the second embodiment. The detection position selection means 9 receives θ1 to θ4 which are outputs of the first rotation position detector 41, the second rotation position detector 42, the first rotation position estimation means 2 and the second rotation position estimation means 7. Then, the estimated rotational position value θ is output. The detection position selection means 9 first determines whether θ1 and θ2 that are the outputs of the two rotational position detectors are substantially the same. When the outputs are substantially matched, θ1 is used. However, when θ1 and θ2 are different, it cannot be determined which rotational position detector is out of order. Therefore, the output θ3 of the rotational position estimating means 2 is used to determine which is outputting correctly. Next, it is determined whether or not θ1 and θ3 substantially match. If the outputs substantially match, θ1 is used. If the outputs of θ1 and θ3 are different, it is determined whether θ2 and θ3 are substantially the same. When the outputs are almost the same, θ2 is used. If θ2 and θ3 are different, it is determined whether θ3 and θ4 are substantially the same. When the outputs are almost the same, θ3 is used. When the outputs of θ3 and θ4 are different, θ4 is used.

  By configuring the detection position selection means 9 as shown in FIG. 7, even if either the first rotational position detector 41 or the second rotational position detector 42 fails, the normal one Rotational position detectors can be used. Thereby, the steering force can be assisted as usual in the electric power steering.

  When both the first rotational position detector 41 and the second rotational position detector 42 fail, the steering force can be assisted by using the first rotational position estimation means 2. In addition, even when the output of the first rotational position estimating means 2 is abnormal, the second rotational position estimating means 7 can be used, so that a quadruple redundant system can be provided at low cost.

  When both the output θ1 of the first rotational position detector 41 and the output θ2 of the second rotational position detector 41 become abnormal and malfunction, the detection position selection means 9 uses the first rotational position estimation means 2 and the first rotational position estimation means 2. Θ3 and θ4, which are the outputs of the rotational position estimating means 7 of No. 2, are used. At this time, the driver is notified of the failure, and the output of the three-phase synchronous motor is gradually decreased. In this way, even when the electric power steering system fails, the driver can safely stop the vehicle.

  The comparison targets θ1, θ2, θ3, and θ4 are corrected at the same time by correcting the three positions by correcting the detection timing of the rotational position detector. By doing in this way, since the rotation position at the same timing can be detected appropriately, erroneous detection can be prevented when comparing the rotation positions.

1: Detection position determination means 2: Rotation position estimation means (first rotation position estimation means)
21: Neutral point potential detection unit 22: Sample / hold unit 23: Rotation position estimation unit 3: Power converter 31: DC power supply 32: Power conversion circuit 33: Pulse width modulation signal output means 34: Virtual neutral point potential detection Circuit 35: Three-phase current detector 36: Shunt current detector 4: Three-phase synchronous motor 41: First rotational position detector 42: Second rotational position detector 5: Control unit 6: Driving of three-phase synchronous motor Device 7: Second rotational position estimating means 8: Electric power steering device 81: Steering wheel 82: Torque sensor 83: Steering assist mechanism 84: Steering mechanism 85: Tire 9: Detection position selecting means

Claims (5)

A control device that controls the three-phase synchronous motor based on signals from a first rotational position detector and a second rotational position detector that detect a rotor position of the three-phase synchronous motor,
A rotational position estimating means for calculating a rotor position based on a neutral point potential or a virtual neutral point potential of the three-phase synchronous motor;
When the output signal of the first rotational position detector is different from the output signal of the second rotational position detector, the first rotational position is based on the rotor position calculated by the rotational position estimating means. A control apparatus for a three-phase synchronous motor, wherein either one of an output signal of a detector or an output signal of the second rotational position detector is selected to control the three-phase synchronous motor. A control device for a three-phase synchronous motor according to claim 1,
When the output signal of the first rotational position detector substantially coincides with the output signal of the second rotational position detector, the three-phase synchronous motor is based on the output signal of the first rotational position detector. A control device for a three-phase synchronous motor, characterized by controlling the motor. A control device for a three-phase synchronous motor according to claim 1 or 2,
When an abnormality is detected in either the first rotational position detector or the second rotational position detector, both the first rotational position detector and the second rotational position detector are normal. The three-phase synchronous motor control device controls the three-phase synchronous motor so as to output a torque equivalent to that of the case. A control device for a three-phase synchronous motor according to any one of claims 1 to 3,
And a three-phase synchronous motor controlled by the control device. A control device for a three-phase synchronous motor according to any one of claims 1 to 3,
A three-phase synchronous motor controlled by the control device;
An electric power steering apparatus comprising: a steering mechanism capable of turning a tire by output torque of the three-phase synchronous motor.

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