JP2016197015A - Rotor position detector abnormality determining device for electric motor control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably determine any abnormality in information on a rotor position detector 2 due to mechanical vibration, such as vibration resulting from its faulty fitting to a motor 1.SOLUTION: An electric motor control apparatus having a speed control system (a speed calculator 3 and a speed controller 4) that controls speed according to detection information from a rotor position detector 2 and a current control system (a current controller 8) that controls current with the output of a dq converter 6 that converts the three-phase detection current of a motor 1 into a d-q axis with reference to the detection information from the detector 2 is further equipped with a harmonic detector 11 that extracts from a d-axis current Id a vibration component Id_h of the d-axis current Id obtained by the dq converter 6, and an encoder information abnormality determining unit 12 that determines whether or not the vibration component of the d-axis current extracted by the harmonic detector 11 is caused by any mechanical factor and, if it is, determines that, when the vibration component remains for a set length of time or longer, the detection information from the rotor position detector 2 is abnormal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotor position detector abnormality determination device in a power converter that acquires rotor position / speed information of an electric motor using a rotor position detector such as a rotary encoder and controls the electric motor.

  As a device for controlling the electric motor based on detection information of a rotor position detector (position / speed sensor) attached to the electric motor, for example, a vector control type electric motor control device with a position / speed sensor shown in FIG. 4 is employed. .

  In FIG. 4, reference numeral 1 denotes a three-phase motor, and a rotor position detector 2 that detects a rotor position (rotation angle) is attached to the motor 1. Reference numeral 3 denotes a speed calculation unit that calculates the rotational speed of the motor from the detection signal of the rotor position detector 2. Reference numeral 4 denotes a speed control unit that controls the rotational speed calculated by the speed calculation unit 3 to be the speed command value of the speed command unit 5 and outputs a current command value.

  6 shows a three-phase detection current obtained by detecting a three-phase (u, v, w) current flowing in the motor 1 by a current transformer (current sensor) 7, and position information of the rotor obtained by the rotor position detector 2. That is, it is a dq conversion unit that performs three-phase to two-phase conversion and rotational coordinate conversion based on phase information.

  Reference numeral 8 denotes a current control unit that controls the dq-axis current converted by the dq conversion unit 6 to be a current command value output from the speed control unit 4 and outputs a dq-axis voltage command value.

  9 is a two-phase to three-phase conversion of the dq-axis voltage command value output from the current control unit 8 on the basis of the rotor position information obtained by the rotor position detector 2, that is, the phase information. And a three-phase converter that outputs voltage commands for each of the three phases.

  Reference numeral 10 denotes a power converter (inverter) that has, for example, a semiconductor switching element connected in a three-phase bridge, and supplies three-phase AC power to the motor 1 based on a voltage command from the three-phase converter 9. The PWM modulation unit is controlled by a control signal (gate signal of the semiconductor switching element) generated by PWM modulating the voltage command of the three-phase conversion unit 9.

  As described above, when vector control with a position / speed sensor (rotor position detector 2) is performed, speed control and current control are performed using sensor position / speed information.

  The UVW three-phase coordinate system, the αβ fixed coordinate system, and the dq rotational coordinate system in vector control in which three-phase to two-phase conversion and rotational coordinate conversion are performed are defined as shown in FIG. That is, each axis of the three-phase current UVW is converted to the αβ axis by three-phase to two-phase conversion, and converted to the dq axis by rotational coordinate conversion. Each of the dq axes is a direct current amount.

  At the steady speed, the dq axes each have a constant value, but when the speed command is changed, the value shifts to a value like the dq axis value at the speed command value. During this transition, the dq axis value has a vibration component in a transient state.

  In the dq converter 6, the dq coordinate axis can be arbitrarily defined after the uvw → dq conversion, but generally the d axis coincides with the magnetic flux of the motor in order to easily control the motor torque. To control. When coordinates for control are defined in the rotating coordinate system, coordinate conversion is performed based on position information of the rotor obtained from, for example, a rotary encoder (rotor position detector 2), that is, phase information. The dq axes rotate in synchronization with the rotation frequency in the case of a synchronous motor, and rotate in synchronization with the frequency on the primary winding side in the case of an induction motor (IM). The current value obtained by coordinate conversion on the dq axis is a direct current amount.

As the rotor position detector 2, for example, a rotary encoder (absolute encoder) shown in FIG. 6 is used. In FIG. 6, reference numeral 60 denotes a rotating disk provided rotatably by a rotating shaft 61. The rotating disk 60 displays a plurality of disk tracks D _{1 to} D _n (only two tracks are shown in the figure). Is formed).

  A light source 63 is provided above the rotating disc 60 via a lens 62, and a light receiving element 65 is provided below the rotary disc 60 via a fixed slit plate 64 having a plurality of fixed slits.

The light from the light source 63 is received by the light receiving element 65 through the lens 62, the disk tracks D _{1 to} D _n and the fixed slit plate 64, and an absolute position signal having a predetermined bit configuration is obtained from the output signal of each light receiving element 65. .

  In addition, the thing of the patent document 1 is proposed as an abnormality and deterioration diagnostic apparatus of the electrical equipment relevant to this invention, for example.

JP 2003-156547 A

  In the apparatus that performs speed control and current control using the detection information (position / speed information) of the rotor position detector 2 as shown in FIG. 4, the detection information of the rotor position detector 2 is incorrect. In addition, speed control and current control cannot be appropriately performed. For this reason, when a sudden speed fluctuation or load fluctuation occurs, an overcurrent failure or an overspeed failure may occur and the device may be broken.

  Furthermore, when the position / speed information of the rotor position detector 2 has oscillated, the output current includes harmonic components and the loss increases. In the case of a permanent magnet synchronous motor (PM motor), the increased loss becomes heat, and the temperature of the rotor magnet may rise and demagnetize.

  For example, in the control device of FIG. 4 in which the rotary encoder of FIG. 6 is adopted as the rotor position detector 2, when the rotary encoder causes a mounting failure and a coupling abnormality of the motor 2 occurs, the output signal of the rotary encoder May vibrate.

  As shown in FIG. 6, the rotating disk 60 attached to the rotating shaft 61 is a movable part, and other components are fixed. Therefore, when the rotary encoder itself is subjected to mechanical vibration, it should originally exist. Since the positional relationship among the fixed light source 63, the lens 62, the fixed slit plate 64, and the light receiving element 65 is blurred, phase blurring occurs in the output of the rotary encoder. For this reason, the phase signal input to the dq converter 6 is also blurred. For this reason, since the phase information used for coordinate conversion vibrates, the current on the dq axis also vibrates. This vibration component becomes a harmonic component, and the loss of the motor increases.

  In the case of a permanent magnet synchronous motor (PM motor), if the loss increases, the temperature of the rotor magnet may rise and demagnetize. Also in the case of an induction motor (IM), there is a risk of short circuit due to deterioration of the insulator or burning of some material. In addition, since the control performance is deteriorated, when a sudden speed fluctuation or load fluctuation occurs, an overcurrent failure or an overspeed failure may occur, and the device may be broken. At present, in order to prevent these problems, there is no function for determining whether or not there is an abnormality such as a failure by the encoder information regardless of the type of the rotary encoder.

  The present invention solves the above-described problems, and its purpose is to reliably determine that information on the rotor position detector is abnormal due to mechanical vibration, for example, vibration generated due to a mounting failure on the electric motor. An object of the present invention is to provide a rotor position detector abnormality determination device for an electric motor control device.

The rotor position detector abnormality determination device for an electric motor control device according to claim 1 for solving the above-mentioned problem is an electric motor control device for controlling an electric motor based on detection information of a rotor position detector attached to the electric motor. In
A vibration component extraction unit that extracts a vibration component of the d-axis current from the d-axis current obtained by converting the three-phase detection current of the electric motor into the dq axes;
It is determined whether or not the vibration component of the d-axis current extracted by the vibration component extraction unit is a vibration caused by a mechanical factor. When the vibration component is a vibration caused by a mechanical factor, the vibration component continues for a set time or more. A rotor position detector information abnormality determination unit that determines that the detection information of the rotor position detector is abnormal when the information is detected.

  According to the above configuration, the abnormality determination is performed based on the vibration component of the d-axis current obtained by converting the detected current of the motor to the dq axis, and therefore, it is generated due to mechanical vibration, for example, an attachment failure to the motor. It can be reliably determined that the information of the rotor position detector is abnormal due to the vibration.

Further, the rotor position detector abnormality determining device of the electric motor control device according to claim 2 is the rotor position detector information abnormality determining unit according to claim 1,
An effective value calculation unit for calculating an effective value of the vibration component of the d-axis current;
A first comparison unit that compares a first determination value set to a current value corresponding to noise other than vibration caused by a mechanical factor and the calculated effective value;
A counter that counts the time when the comparison result of the first comparison unit is larger in effective value than the first determination value;
A second comparison unit that compares the second determination value set to the allowable time of AC component generation and the count time of the counter;
When the comparison result of the second comparison unit shows that the count time of the counter is longer than the second determination value, it is determined that the detection information of the rotor position detector is abnormal.

  According to the above configuration, since the first comparison unit is provided, it is possible to prevent erroneous determination due to noise other than vibration caused by mechanical factors.

  In addition, since the second comparison unit is provided, it is erroneously determined based on the AC component generated within the AC component generation allowable time, for example, the high-frequency current component generated when a transient speed fluctuation occurs in the motor. Can be prevented.

According to a third aspect of the present invention, there is provided the rotor position detector abnormality determining device for the electric motor control device according to the first or second aspect, wherein the electric motor control device is:
A speed control system that controls the speed according to detection information of the rotor position detector;
And a current control system that controls the current by the output of a coordinate conversion unit that converts the three-phase detection current of the motor into dq axes with reference to detection information of the rotor position detector.

  According to the above configuration, speed control and current control are performed based on abnormal detection information output from the rotor position detector, and it is possible to prevent an overspeed failure or an overcurrent failure from occurring.

  According to a fourth aspect of the present invention, there is provided the rotor position detector abnormality determining device according to any one of the first to third aspects, wherein the vibration component extraction unit includes a high-pass filter.

  According to a fifth aspect of the present invention, there is provided the rotor position detector abnormality determining device of the motor control device according to any one of the first to third aspects, wherein the vibration component extraction unit is only in a frequency band corresponding to mechanical vibration. A band-pass filter that passes the filter is provided.

(1) According to the inventions of the first to fifth aspects, the abnormality determination is performed based on the vibration component of the d-axis current obtained by converting the detected current of the electric motor to the dq axis. It is possible to reliably determine that the information on the rotor position detector is abnormal due to vibration, for example, vibration generated due to a mounting failure in the electric motor.
(2) According to the invention described in claim 2, it is possible to prevent erroneous determination due to noise other than vibration caused by mechanical factors, and AC component generated within the allowable time of AC component generation, and improve determination accuracy. it can.
(3) According to the invention described in claim 3, speed control and current control are performed based on abnormal detection information output from the rotor position detector, thereby preventing an overspeed failure or an overcurrent failure from occurring. Can do.

The block diagram which shows the structure of the example of embodiment of this invention. The block diagram which shows the principal part detail in Example 1 of this invention. The block diagram which shows the principal part detail in Example 2 of this invention. The block diagram which shows an example of the electric motor control apparatus with which this invention is applied. Explanatory drawing which shows the definition of the control coordinate axis in vector control. The block diagram of the absolute encoder to which this invention is applied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. FIG. 1 shows the configuration of the present embodiment, and the same parts as those in FIG.

  1 differs from FIG. 4 in that harmonic detection is performed by extracting vibration components (alternating current components) of the d-axis current, that is, harmonics, from the d-axis current of the dq-axis current converted by the dq conversion unit 6. It is determined whether the vibration component of the d-axis current extracted by the unit 11 (vibration component extraction unit) and the harmonic detection unit 11 is a vibration caused by a mechanical factor, and is a vibration caused by a mechanical factor. In this case, an encoder information abnormality determination unit 12 (rotor position detector information abnormality determination unit) that determines that the detection information of the rotor position detector 2 is abnormal when the vibration component continues for a set time or longer, The other parts are the same as in FIG.

  For example, a rotary encoder shown in FIG. 6 is used for the rotor position detector 2. In the following description, the rotor position detector may be simply referred to as an encoder.

  The current information obtained by detecting the current flowing through the motor 1 with a current transformer 7 (current sensor) is subjected to three-phase to two-phase conversion and rotational coordinate conversion by the dq conversion unit 6. There are two components: a detection value (Id) and a q-axis current detection value. In the present embodiment example, as shown in FIG. 1, the correctness / incorrectness of the encoder information is determined from the information of the detected d-axis current value.

  The d-axis current detection value (Id) after the rotational coordinate conversion by the dq conversion unit 6 is a direct current amount and normally does not vibrate. Therefore, the vibration detection component (Id_h) of the d-axis current is extracted by the harmonic detection unit 11, and the encoder information abnormality determination unit 12 determines whether or not the vibration component is a vibration caused by a mechanical factor. The correctness / incorrectness of the information is determined. If there is an error, it is determined that the information is abnormal.

  The harmonic detection unit 11 and the encoder information abnormality determination unit 12 will be described in detail in Examples 1 and 2 below.

  FIG. 2 shows a detailed configuration of the harmonic detection unit 11 and the encoder information abnormality determination unit 12 in FIG. Reference numeral 11a denotes a harmonic detection unit including a high-pass filter (HPF) that performs high-band pass processing on the d-axis current detection value Id to extract a vibration component Id_h of the d-axis current.

  The vibration component Id_h of the d-axis current, which is the output of the harmonic detection unit 11a, becomes an AC component waveform and is input to an effective value calculation (Root Mean Square; RMS) unit 21 of the encoder information abnormality determination unit 12. The effective value calculator 21 calculates an effective value of the vibration component Id_h and extracts an effective value component.

  22 compares the effective value component output from the effective value calculation unit 21 with the first determination value (determination value 1) for preventing erroneous determination due to noise. When the effective value is larger, “1” Is a first comparison unit that outputs "." Note that the first comparison unit 22 outputs “0” when the first determination value is larger.

  The first determination value is set to a value having an amplitude of, for example, about 5% with respect to the rated current value. That is, the harmonic component of the d-axis current basically does not occur except for the vibration component of the speed sensor (encoder: rotor position detector 2) and the current sensor (current transformer 7).

  Therefore, the first determination value may be set to about 5% of the rated current value in order to prevent erroneous detection and erroneous determination due to noise other than vibration components caused by mechanical factors. This improves the determination accuracy.

  The output of the first comparison unit 22 is input to the up counter 23 (counter). In the up counter 23, when the first comparison unit 22 outputs “1” (a harmonic is generated), the state continues. Calculate (count) the time to perform.

  24 compares the count time output from the up-counter 23 with the second determination value (determination value 2) for preventing erroneous determination due to the AC component generated within the allowable time. This is a second comparison unit that outputs “1” when it is large (the harmonic generation duration exceeds the allowable time) and determines that the encoder information is abnormal. Note that the second comparison unit 24 outputs “0” when the second determination value is larger.

  The second determination value is set to a value in minutes. That is, for example, when a transient speed fluctuation occurs in the motor 1, a high-frequency current component is generated, but the electric time constant of the motor is not as long as minutes. Therefore, by setting the second determination value in minutes, there is no erroneous determination due to the transient speed fluctuation of the motor, and vibration due to abnormal mechanical attachment of the encoder (rotor position detector 2). It can be determined that there is. This improves the determination accuracy.

  When it is determined that the encoder information is abnormal, for example, the motor 1 can be stopped.

  According to the first embodiment, speed control and current control are performed based on abnormal detection information output from the rotor position detector 2, and it is possible to prevent an overspeed failure or an overcurrent failure from occurring.

  The vibration component Id_h of the d-axis current that is the output of the harmonic detection unit 11 has a frequency in a band close to the output frequency component of the motor, not an AC component such as noise. That is, vibrations caused by mechanical factors do not become high frequency components such as noise.

  Therefore, in this second embodiment, instead of the harmonic detection unit 11a of the first embodiment (FIG. 2), as shown in FIG. 3, the vibration component of the d-axis current is extracted for the low frequency region and the high frequency region is extracted. Employs a harmonic detection unit 11b having a band pass filter (BPF) having a pass band for cutting a band like noise. In FIG. 3, the encoder information abnormality determination unit 12 is configured in the same way as in FIG.

  3 also operates in the same manner as in FIG. 2, and from the d-axis current (Id) obtained by converting the three-phase detection current of the motor 1 to the dq axis, the vibration component ( Id_h) is extracted, it is determined whether or not the vibration component is a vibration caused by a mechanical factor, and when the vibration component duration when the vibration component is a vibration caused by a mechanical factor exceeds an allowable time, an encoder ( It can be determined that the detection information of the rotor position detector 2) is abnormal.

  As described above, according to the present embodiment, it is possible to monitor an encoder attachment abnormality and appropriately perform motor control based on the abnormality determination result.

  Further, when an encoder attachment abnormality occurs, the motor loss increases. In the case of a permanent magnet synchronous motor (PM), if the loss increases, the temperature of the rotor magnet may rise and demagnetize. In the case of an induction motor (IM), a short circuit due to deterioration of an insulator or burning of some substances However, according to the present embodiment, the electric motor can be protected from them.

  The present invention is not limited to the motor control device shown in FIG. 1, and can be applied to motor control devices having other configurations. In this case, the same operations and effects as described above can be achieved.

DESCRIPTION OF SYMBOLS 1 ... Motor 2 ... Rotor position detector 3 ... Speed calculation part 4 ... Speed control part 5 ... Speed command part 6 ... dq conversion part 7 ... Current transformer 8 ... Current control part 9 ... Three-phase conversion part 10 ... Power conversion 11, 11 a, 11 b... Harmonic detection unit 12... Encoder information abnormality determination unit 21... Effective value calculation unit 22... First comparison unit 23 ... up counter 24 ... second comparison unit 60. axis 62 ... lens 63 ... light source 64 ... fixed slit plate 65 ... light-receiving element D ₁ to D _n ... disk track

Claims (5)

In the motor control device that controls the motor based on the detection information of the rotor position detector attached to the motor,
A vibration component extraction unit that extracts a vibration component of the d-axis current from the d-axis current obtained by converting the three-phase detection current of the electric motor into the dq axes;
It is determined whether or not the vibration component of the d-axis current extracted by the vibration component extraction unit is a vibration caused by a mechanical factor. When the vibration component is a vibration caused by a mechanical factor, the vibration component continues for a set time or more. The rotor position detector information abnormality determination unit for determining that the detection information of the rotor position detector is abnormal,
A rotor position detector abnormality determination device for an electric motor control device comprising: The rotor position detector information abnormality determination unit is
An effective value calculation unit for calculating an effective value of the vibration component of the d-axis current;
A first comparison unit that compares a first determination value set to a current value corresponding to noise other than vibration caused by a mechanical factor and the calculated effective value;
A counter that counts the time when the comparison result of the first comparison unit is larger in effective value than the first determination value;
A second comparison unit that compares the second determination value set to the allowable time of AC component generation and the count time of the counter;
The comparison result of the second comparison unit determines that the detection information of the rotor position detector is abnormal when the count time of the counter is longer than the second determination value. Rotor position detector abnormality determination device of the electric motor control device. The motor controller is
A speed control system that controls the speed according to detection information of the rotor position detector;
A current control system for controlling the current by the output of the coordinate conversion unit that converts the three-phase detection current of the motor into the dq axes with reference to the detection information of the rotor position detector;
The rotor position detector abnormality determination apparatus of the electric motor control apparatus of Claim 1 or 2 provided with these.   The rotor position detector abnormality determination device for an electric motor control device according to any one of claims 1 to 3, wherein the vibration component extraction unit includes a high-pass filter.   The rotor position detector abnormality determination of the motor control device according to any one of claims 1 to 3, wherein the vibration component extraction unit includes a band-pass filter that passes only a frequency band corresponding to mechanical vibration. apparatus.

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