JP5083016B2 - Electric motor control device, control method, and elevator device - Google Patents

Description

  The present invention relates to a motor control device, a control method, and an elevator apparatus that control an AC motor, and more particularly to offset compensation of a current detector.

  When the elevator drive source is an electric motor, the electric motor is generally used to improve the landing accuracy and ride comfort of the elevator car and to enable smooth speed control in a wide range of rotation speeds (from start to stop). It is operated by a vector control type inverter.

  FIG. 5 is a block diagram showing an example of a conventional general elevator apparatus. As shown in FIG. 5, the elevator apparatus includes a converter 2 that converts AC power output from a power source (for example, a three-phase AC power source) 1 into DC power, and converts the converted DC power into a desired voltage and a desired voltage. Inverter 3 for converting to AC power having a frequency, electric motor 4 for generating power by the converted AC power, and each current detector 5a for detecting at least two-phase current among the three-phase current flowing through the motor 4. , 5b, a car 6 that travels (or stops) over each floor by driving the electric motor 4, an encoder 7 that detects the rotational speed of the electric motor 4, and a landing or a call of the car 6 to the corresponding floor. An operation control unit 8 that outputs an operation command for running (or stopping) and a speed command to the electric motor 4, and an inverter control that controls the current and speed of the electric motor 4. And part 9, the was composed mainly. Reference symbol A denotes an electric motor control device including the inverter 3, current detectors 5 a and 5 b, and an inverter control unit 9.

  The inverter control unit 9 includes a speed command output from the operation control unit 8, a speed detection signal output from the encoder 7, detection current values Iu and Iw output from the current detectors 5a and 5b, Is input, and feedback control is performed so as to eliminate the deviation between the speed command and the speed detection signal and the deviation between the current command and the detected current values Iu and Iw. That is, the inverter control unit 9 calculates the deviation between the speed command and the speed detection signal and converts it into a current command, calculates the deviation between the current command and the detected current values Iu and Iw, and controls the current of the motor 4. Do.

  It is known that the control accuracy in the motor control device A configured as described above largely depends on the detection accuracy of the current detectors 5a and 5b. However, in general, the detected current value detected by the current detectors 5a and 5b has a minute offset due to, for example, the influence of temperature change and aging deterioration (even when the output of the inverter 3 is actually zero). Exists. Since this offset is superimposed as a direct current component on the current output to the motor 4, torque ripple occurs in the motor 4. The torque ripple in the electric motor 4 causes vibrations in the car 6 and deterioration in riding comfort, abnormal noise generation in the electric motor 4, abnormal heat generation, and the like.

  In addition, in the motor control device A as described above, a current detector (Hall CT) having a combination of a Hall element and a magnetic material is necessary because it is necessary to detect a current from DC to AC of about 200 Hz. However, if a magnetic material (magnetic material) is used in this way, it will be affected by residual magnetism.

  When affected by the residual magnetism as described above, for example, a hysteresis characteristic of the detected current value with respect to the actual current appears as shown in FIG. 6 (the vertical axis is the detected current and the horizontal axis is the actual current), and the actual current is large (described later). If the actual current is small (smaller than a), the characteristic b occurs. That is, as shown in FIG. 6, when the actual current is large, the hysteresis errors Δd and −Δd are also large, and when the actual current is small, the hysteresis errors Δd ′ and −Δd ′ are also small values (however, Hysteresis is not necessarily proportional).

  In general motor control device A, in order to perform feedback control of the motor with high accuracy, for example, as shown in FIG. 7, an offset compensation unit (reference numerals 17a and 17b described later) including a circuit 10 and a subtraction unit 11 is provided. It is used. This circuit (hereinafter referred to as a sample and hold circuit) 10 samples (samples) the detected current values Iu and Iw detected while the inverter 3 is stopped as an offset value. The offset value can be held (stored). The subtracting unit 11 subtracts the offset value (the offset value stored in the sample and hold circuit 10) from the detected current values Iu and Iw detected during the inverter operation.

  That is, a method of subtracting the offset value sampled when the inverter 3 is stopped (when stopped before starting again) from the detected current values Iu and Iw when the inverter 3 is operated next time (when it is restarted and then restarted). is there.

  However, the offset value sampled when the inverter 3 is stopped is a value different from the original offset value because the hysteresis error is not taken into consideration. Therefore, when the offset is compensated by the above method (the method of subtracting the offset value sampled when the inverter 3 is stopped from the detected current values Iu and Iw at the next operation of the inverter 3), the desired compensation (the original offset value is compensated). ) Is not effective, and as a result, a DC component is superimposed on the current output to the motor, and torque ripple occurs in the motor 4.

  Further, since the offset value sampled through a general current detector (current detector using Hall CT) is influenced by the hysteresis characteristic, the actual current value before the inverter 3 is stopped. The size and polarity vary depending on the polarity. That is, for example, in the case of an apparatus such as an elevator apparatus in which the load condition varies depending on the driving direction and the load condition in the car 6, the hysteresis error due to the influence of the residual magnetism becomes a different value each time. The sampled offset value also changes every time.

In recent years, several proposals have been made as methods for calculating the offset value in order to solve the above-described problems. For example, there is a method of calculating the offset value (DC component) by averaging the detected current value (AC signal) of the motor during constant speed operation for an integer multiple of the period (for example, Patent Document 1). In addition, there is a method of storing a detected current value in an internal memory every time the inverter stops, and using an average value of a plurality of detected current values stored in the past as an offset value (for example, Patent Document 2).
JP 07-170799 A (paragraphs [0012] to [0040], FIG. 1) JP-A-10-164485 (paragraphs [0011] to [0020], FIG. 1)

  However, in Patent Document 1, the detected current value during constant speed operation is averaged to calculate the offset value (DC component). For example, the constant speed period of the motor in the elevator apparatus is usually long and is one minute. Therefore, sufficient averaging processing cannot be performed, and the calculated offset value may have a low accuracy, resulting in an error.

  Moreover, in patent document 2, since the influence of a residual magnetism becomes small when an inverter stop period is long, the devices, such as using the offset value just before a driving | operation start, are made | formed. However, when the offset values (DC components) for the past multiple times sampled when the inverter is stopped are averaged, it is not assumed what kind of operation state the offset value is stored after. That is, when the past operating state is biased (for example, when the detected current value is continuously stored in a state where the maximum amplitude value is large), it differs from the original offset value due to the influence of the hysteresis error (for example, Large) offset values are stored, which may cause errors.

  As described above, the object of the present invention is to compensate for the influence of the hysteresis characteristic, calculate a highly accurate offset value so that the above error does not occur, and to accurately calculate based on the true detected current value. The object is to provide an electric motor control device.

  The present invention has been devised in view of the conventional problems, and the invention according to claim 1 is directed to an inverter for outputting a three-phase alternating current for driving an electric motor, and at least of the three-phase alternating current. A current detector for detecting a two-phase current; and an offset compensator for compensating for an offset value included in the detected current value detected by each of the current detectors and outputting a compensated detected current value. The offset compensator is configured to divide and define the entire range of the compensation detection current value that can be detected during inverter operation into a plurality of storage areas corresponding to the divided ranges. Each time the operation of the inverter is stopped, each of the divided ranges is selected based on the magnitude and polarity of the maximum amplitude value before the inverter is stopped. Together, it stores the detected current value after the inverter stops the storage area according to the selected divided range, and calculates the average value of the detected current value in the stored entire storage area has been as an offset value.

  According to a second aspect of the present invention, in the first aspect of the present invention, data is stored so that the number of data stored in each storage area among the data in the detected current values stored in all the storage areas is the same. Extracting, summing the extracted data, and dividing the sum by the total number of the extracted data, calculating an average value of the detected current values in all the storage areas.

  According to a third aspect of the invention, in the first aspect of the invention, the average value of the latest detected current values for each storage area is calculated for each storage area, and the average value in the entire range is calculated from the average value in each of the storage areas. It is characterized by calculating.

  According to a fourth aspect of the present invention, in the invention of the third aspect, when calculating the average value in all the storage areas from the average value in the storage area, the weights for differently weighting the average values in the respective storage areas A moving average process is performed.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the storage means is configured by a separate memory for each storage area.

The invention according to claim 6 is the invention according to claims 1 to 5, wherein the storage means is a nonvolatile memory. The invention according to claim 7 is any one of claims 1 to 6. It is an elevator apparatus provided with the control apparatus of the electric motor of description, Comprising: The said motor drives the winding machine which drive | works a passenger car, It is characterized by the above-mentioned.

  The invention according to claim 8 is included in a current detector that detects at least two-phase current out of three-phase alternating current output from the inverter to the motor, and a detected current value detected by each of the current detectors. And an offset compensator for compensating the offset value, and a method for controlling the electric motor that performs current feedback control using the offset compensator, wherein the offset compensator divides the entire range of compensation detection current values that can be detected during inverter operation into a plurality of ranges. Each of the divided ranges based on the magnitude and polarity of the maximum amplitude value before the inverter is stopped each time the operation of the inverter is stopped. A selection step for selecting one of them, a storage step for storing the detected current value after the inverter stops in the storage area related to the selected divided range, And an offset value calculation step of calculating an offset value the average value of the detected current value in the stored entire storage area has been in the process, and performing.

  The invention according to claim 9 is the invention according to claim 8, wherein the selection step includes a polarity determination step for determining the polarity of the compensation detection current value during inverter operation, and a maximum amplitude value in the compensation detection current value. A maximum value update processing step for updating and a division range determination step for determining a division range based on a polarity and a maximum amplitude value in the compensation detection current value are performed.

  According to the configuration of the first to ninth aspects of the present invention, even when the past operating state is biased, it is possible to compensate for the influence of the hysteresis characteristic and suppress the error of the offset value.

  According to the configuration of the sixth aspect of the invention, even if the control power is turned off, the data stored in the memory does not disappear.

  According to the configuration of the fourth aspect of the invention, even when the absolute value of the compensation detection current value during inverter operation is large, it is possible to compensate for the influence of the hysteresis characteristic and suppress the error of the offset value. .

  As apparent from the above description, according to the first to ninth aspects of the present invention, the offset included in the detected current value of the inverter can be compensated with high accuracy, and the occurrence of torque ripple in the motor is suppressed. It becomes possible to do. Moreover, since it can respond also to aged deterioration and a temperature change of a current detector, it can suppress that a torque ripple generate | occur | produces in a motor over a long period of time.

  According to the seventh aspect of the present invention, it is possible to suppress the occurrence of torque ripple in the electric motor and to suppress the deterioration of the riding comfort of the elevator.

  Hereinafter, an electric motor control device and an elevator apparatus according to embodiments of the present invention will be described in detail based on examples. 5 and 6 are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

  In the present embodiment, a current detector that detects at least two-phase current out of three-phase AC current output from the inverter to the motor, and an offset value included in the detected current value detected by each of the current detectors Current feedback control is performed by providing an offset compensator that compensates for.

  In the offset compensator, the entire range of the maximum amplitude value of the compensation detection current value that can be detected during inverter operation can be defined by dividing it into a plurality of ranges (divided ranges r1 to r6 in the embodiments described later). A plurality of data (detected current values after the inverter is stopped) can be classified and stored (for example, stored in a storage area corresponding to each divided range) for each range (hereinafter, each is referred to as a divided range). For example, the detection current value after the inverter is stopped is stored by first selecting any one of the divided ranges based on the magnitude and polarity of the maximum amplitude value of the compensation detection current value before the inverter is stopped. And stored as related to the divided range. Then, the average value of the detected current values stored as described above is calculated as an offset value (for example, the average value of the latest detected current values for each divided range is calculated, and the average value of each divided range is calculated. To calculate the average value in the entire range.

[Example 1]
FIG. 1 is a block diagram of an elevator apparatus according to the present embodiment. In the figure, each calculation and conversion block is shown separately in the drawing, but in actuality, it is constituted by a hardware configuration or a control computer and its software.

In FIG. 1, the speed control of the electric motor 4 is output from the operation control unit 8 according to the speed command corresponding to the calling floor or landing floor of the car 6, the acceleration command at the time of starting up and down, and the number of passengers (weight measurement). The speed control unit 13 performs the load command and the speed detection signal ωr output from the encoder 7 via the speed detection unit 12. That is, the speed control unit 13 obtains a speed set value by digital calculation from the speed command, acceleration command, and load command from the operation control unit 8, and calculates the difference between the speed set value and the speed detection signal ωr (for example, The result of proportional integration (PI) calculation) is output as a torque command T ^* . The torque control unit 14 separates the torque command T ^* into a torque current command Id ^* and an excitation current command Iq ^* .

  The angular velocity detection unit 16 adds a velocity detection signal ωr and a slip angular frequency (not shown) to obtain a primary angular frequency ω, and outputs the primary angular frequency ω to a current control unit 15 described later. The detected current values Iu and Iw detected by the current detectors 5a and 5b are subtracted from the offset values by the u-phase offset compensator 17a and the w-phase offset compensator 17b in the offset compensator 17. Converted to Iu ′ and Iw ′. The compensation detection current values Iu ′ and Iw ′ are determined by the three-phase / two-phase conversion unit 19 based on the rotational phase θ of the electric motor 4 detected by the position detection unit 18 and d and q-axis feedback current values Id and Iq. And is input to the current control unit 15.

The torque current command Id ^* and the excitation current command Iq ^* are converted into voltage commands Vd ^* and Vq ^* on the basis of the feedback current values Id and Iq and the primary angular frequency ω by the current control unit 15 to obtain two-phase / Output to three-phase converter 20. The voltage commands Vd ^* and Vq ^* are converted into three-phase voltage control signals Vu ^* and Vv based on the value of the rotational phase θ of the motor 4 detected by the position detector 18 in the two-phase / three-phase converter 20. ^* , Converted to Vw ^* . The PWM control unit 21 receives voltage control signals Vu ^* , Vv ^* , and Vw ^{* and} performs PWM control of the inverter 3 based on the values of the voltage control signals Vu ^* , Vv ^* , and Vw ^* .

  The offset compensator 17a of the offset compensator 17 in the electric motor control apparatus A according to the first embodiment can be defined by dividing the entire range of the compensation detection current value Iu ′ that can be detected during the operation of the inverter 3 into a plurality of divided ranges. The storage means (not shown) having a storage area corresponding to is stored, and the maximum amplitude value and polarity of the compensation detection current value Iu ′ during operation of the inverter 3 are stored every time the polarity changes. Further, when the inverter 3 is stopped, any one of the divided ranges is selected based on the magnitude and polarity of the maximum amplitude value of the compensation detection current value Iu ′ before the inverter 3 is stopped, and the detection when the inverter 3 is stopped is detected. The current value Iu is stored in the storage area related to the selected division range. Further, average values of the detected current values Iu stored in the respective storage areas (for example, average values calculated by moving average processing of the latest detected current values Iu for a plurality of times) are calculated, respectively. From the value, an average value in the entire range of the detected current value Iu ′ that can be detected is calculated.

  The average value calculated as described above is used as offset value data to be subtracted from the detected current value Iu during operation of the inverter 3. In addition, in the method of calculating the offset value from the detected current value stored in each storage area, the same number of data is extracted from all the storage areas and summed, and the summed value is divided by the number of extracted data. It is also possible to do it.

  Since the offset compensator 17b has the same configuration as the offset compensator 17a, a detailed description thereof is omitted here.

  The offset compensator 17 in the first embodiment has, for example, a range equal to or less than six divided ranges (first divided range r1: current detector rated current value (current during rated speed operation) in the positive electrode) as shown in FIG. Second divided range r2: Current detector constant current value at positive electrode not more than 150% and exceeding current detector rated current value, third divided range r3: Range above current detector rated current value 150% at positive electrode, first Divided range r4: Range above current detector rated current value at negative electrode, Fifth divided range r5: Range below current detector rated current value at negative electrode and current detector rated current value 150% or more, Sixth divided range r6 : Compensation detection current values Iu ′ and Iw ′ at the time of operation of the inverter 3 are divided into the current detector rated current of 150% in the negative electrode).

  Further, for example, four data (detected current values Iu and Iw when the inverter is stopped) are stored in each storage area of the storage means in the first embodiment. Assume that old data is erased. In order to prevent the data stored in each storage area from being lost even when the control power is turned off, the storage means is a nonvolatile memory. Further, even if the actual current is turned off, the influence of the residual magnetism of the magnetic material is not lost, so the above operation is performed even for the first operation after turning on the current.

  Next, a specific operation in the offset compensator 17 of the first embodiment will be described with reference to the flowchart of FIG. 3A (steps S1 to S9) shows an operation performed during operation of the inverter 3, and FIG. 3B (steps S11 to S17) shows an operation performed while the inverter 3 is stopped. In addition, since the same operation is performed in each phase in which the offset compensation unit 17 is provided, only the offset compensation unit 17a (u phase) will be described.

  As shown in FIG. 3A, first, during the operation of the inverter 3, after the detection current value Iu is read in the current reading processing step S1, the compensation detection current value calculation processing step S2 is based on the following equation (1). A compensation detection current value Iu ′ (used in control) is calculated and output to the three-phase / two-phase converter 19.

(Detected current value Iu) − (Offset value calculated while the inverter 3 is stopped) = (Compensated detected current value Iu ′) (1)
Next, in the first polarity determination step S3, the polarity of the compensation detection current value Iu ′ calculated by the equation (1) is determined. When it is determined that the compensation detection current value Iu ′ is positive, the process proceeds to the minimum value 0 clear processing step S4, and the minimum value of the compensation detection current value Iu ′ stored in the previous reading from the start of the inverter 3 operation. Is cleared to zero. Thereafter, in the maximum value determination step S5, the maximum value of the compensation detection current value Iu ′ cleared to 0 by the minimum value 0 clear processing step S4 and the compensation detection current value stored in the previous reading from the start of the inverter 3 operation. The maximum value of Iu ′ is compared. In the maximum value determination step S5, when it is determined that the maximum value of the compensation detection current value Iu ′ cleared to 0 by the minimum value 0 clear processing step S4 is larger, the process proceeds to the maximum value update processing step S6. The cleared maximum value of the compensation detection current value Iu ′ is stored (the maximum value of the compensation detection current value Iu ′ in the previous reading is updated from the start of operation of the inverter 3).

  In the maximum value determination step S5, when it is determined that the maximum value of the compensation detection current value Iu ′ stored in the previous reading from the start of the operation of the inverter 3 is larger, the maximum of the compensation detection current value Iu ′ is determined. The value is not updated.

  On the other hand, when the compensation detection current value Iu ′ is determined to be negative in the first polarity determination step S3, the process proceeds to the maximum value 0 clear processing step S7, and the compensation stored in the previous reading from the start of the inverter 3 operation is stored. The maximum value of the detected current value Iu ′ is cleared to zero. Thereafter, in the minimum value determination step S8, the minimum value of the compensation detection current value Iu ′ cleared to 0 by the maximum value 0 clear processing step S7 and the compensation detection current value stored in the previous reading from the start of the inverter 3 operation. The minimum value of Iu ′ is compared. In this minimum value determination step S8, when it is determined that the minimum value of the compensation detection current value Iu ′ that has been cleared to 0 by the maximum value 0 clear processing step S7 is smaller, the process proceeds to the minimum value update processing step S9. The cleared minimum value of the compensation detection current value Iu ′ is stored (the minimum value of the compensation detection current value Iu ′ at the previous reading is updated from the start of operation of the inverter 3).

  In the minimum value determination step S8, if it is determined that the minimum value of the compensation detection current value Iu ′ stored since the previous start of operation of the inverter 3 is smaller, the minimum of the compensation detection current value Iu ′ is determined. The value is not updated. Moreover, the operation | movement to process S1-S9 shall be repeated by a predetermined space | interval (for example, electric current control space | interval).

  Next, as shown in FIG. 3B, in the operation while the inverter 3 is stopped, first, the current polarity of the compensation detection current value Iu ′ immediately before the inverter 3 is stopped is determined to be positive by the second polarity determination step S11. In this case, the process proceeds to the third divided range r3 determination step S12, and it is determined whether or not the maximum value of the compensation detection current value Iu ′ during operation of the inverter 3 falls within the third divided range r3. Here, when the maximum value is not determined to be the third divided range r3, the process proceeds to the second divided range r2 determination step S13, and the second maximum value of the compensation detection current value Iu ′ during the operation of the inverter 3 is determined. It is determined whether or not the division range r2.

  Next, if the maximum value of the compensation detection current value Iu ′ during the operation of the inverter 3 is not determined to be the second divided range r2 in the second divided range r2 determining step S13 by the moving average processing step S14, the first divided range is determined. The range r1 is determined, and the detected current value Iu after the inverter 3 is stopped is stored in the storage area m1 related to the first divided range r1. Conversely, in the second divided range r2 determination step S13, when the maximum value of the compensation detection current value Iu ′ during the operation of the inverter 3 is determined to be the second divided range r2, the storage area m2 related to the second divided range r2 The detected current value Iu after the inverter 3 is stopped is stored. When the maximum value of the compensation detection current value Iu ′ during the operation of the inverter 3 is determined to be the third divided range r3 in the third divided range r3 determining step S12, the inverter is stored in the storage area m3 related to the third divided range r3. The detected current value Iu after 3 stops is stored. Then, the latest detected current values Iu for a plurality of times stored in each storage area as described above are subjected to moving average processing, and an average value in each storage area is calculated.

  Similarly, when it is determined in the second polarity determination step S11 that the current polarity of the compensation detection current value Iu ′ immediately before the inverter 3 stops is negative, the process proceeds to the sixth divided range r6 determination step S15, and the inverter 3 is operated. It is determined whether or not the minimum value of the compensation detection current value Iu ′ is within the sixth division range r6. If the minimum value of the compensation detection current Iu ′ during the operation of the inverter 3 is not determined to be the sixth division range r6 in the sixth division range r6 determination step S15, the process proceeds to the fifth division range r5 determination step S16. It is determined whether or not the minimum value of the compensation detection current value Iu ′ during the three operations is within the fifth divided range r5.

  Next, if the minimum value of the compensation detection current value Iu ′ during the operation of the inverter 3 is not determined to be the fifth division range r5 in the fifth division range r5 determination step S16 by the moving average processing step S14, the fourth division is performed. The range is determined as r4, and the detected current value Iu after the inverter 3 is stopped is stored in the storage area m4 related to the fourth divided range r4. On the other hand, in the fifth divided range r5 determination step S16, when the minimum value of the compensation detection current value Iu ′ during the operation of the inverter 3 is determined to be the fifth divided range r5, the storage area m5 related to the fifth divided range r5. The detected current value Iu when the inverter 3 is stopped is stored. Further, in the sixth divided range r6 determination step S15, when the minimum value of the compensation detection current value Iu ′ during the operation of the inverter 3 is determined to be the sixth divided range r6, the storage area m6 related to the sixth divided range r6 is stored. The detected current value Iu after the inverter 3 is stopped is stored. Then, the latest detected current values Iu for a plurality of times stored in each storage area as described above are subjected to moving average processing, and an average value in each storage area is calculated.

  Finally, in the offset value calculation step S17, the average value in each storage area obtained in the moving average processing step S14 is summed and divided by 6, thereby calculating the offset value.

  By configuring as in the first embodiment, it is possible to compensate for the influence of the hysteresis characteristic and suppress the error of the offset value even when the past operation state is biased. Therefore, the offset value included in the detected current values Iu and Iw can be compensated with high accuracy, and the occurrence of torque ripple in the electric motor 4 can be suppressed. Further, it is possible to cope with aging deterioration and temperature change in the current detectors 5a and 5b, and it is possible to suppress the occurrence of torque ripple in the electric motor 1 over a long period of time.

[Example 2]
Next, another example of the motor control device in the present embodiment will be described. Since the second embodiment has the same configuration as that of the first embodiment except for the operation of the offset compensation unit 17, a detailed description thereof will be omitted here.

  The offset compensator 17 in the motor control device A of the second embodiment has a divided range in which the compensation detection current values Iu ′ and Iw ′ during operation of the inverter 3 exceed the current detector rated current value (for example, the second embodiment). In this case, the average value of the storage area over the second divided range r2, the third divided range r3, the fifth divided range r5, and the sixth divided range r6) decreases the weight before calculating the offset value (ie, The offset value is calculated by the weighted moving average process). For example, in the second embodiment, the storage areas m1 and m4 are weighted 100%, the storage areas m2 and m5 are 50%, and the storage areas m3 and m6 are 25%. In an actual calculation, the average value of the storage areas m1 and m4 is quadrupled, the average value of the storage areas m2 and m5 is doubled, the average value of the storage areas m3 and m6 is multiplied by 1, and then divided by 14. Good.

  Next, a specific operation in the offset compensator 17 of the second embodiment will be described with reference to the flowchart of FIG. Since steps S1 to S9 in FIG. 4A and steps S11 to S16 in FIG. 4B are the same operations as those in the first embodiment, detailed description thereof is omitted here. In addition, since the same operation is performed in each phase in which the offset compensation unit 17 is provided, only the offset compensation unit 17a (u phase) will be described.

  In the second embodiment, as in the first embodiment, the average value in each storage area is calculated by steps S1 to S9 and steps S11 to S16. Thereafter, the average value in the storage areas m1 and m4 is quadrupled by the first weighting process step S18, and the average value in the storage areas m2 and m5 is doubled by the second weighting process step S19.

  Finally, in the offset value calculation step S20, the data in the storage areas m1 and m4 calculated in the first weighting process step S18, the data in the storage areas m2 and m5 calculated in the second weighting process step S19, and the moving average processing step S14 The data in the storage areas m3 and m6 calculated by the above is added and divided by 14 to calculate the offset value.

  By configuring as in the second embodiment, when the absolute value of the compensation detection current value during operation of the inverter 3 is large, the influence of the hysteresis characteristic becomes strong, but the weighted moving average process is adopted. The same effects as those of the first embodiment are obtained.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

  For example, in the first and second embodiments, the configuration in which the storage unit is divided into six storage areas has been described. However, the number of storage areas is not limited to this number, and may be increased or decreased as appropriate depending on the operating conditions of the motor. Is possible. Further, the data stored in the storage area is not limited to four, and can be increased or decreased as appropriate.

  In the second embodiment, as the weighted moving average process, the storage areas m1 and m4 are weighted 100%, the storage areas m2 and m5 are 50%, and the storage areas m3 and m6 are weighted 25%. The breakdown of the weighting can be appropriately changed depending on the operation status of

  Further, in the first and second embodiments, the configuration including the current detector and the offset compensator in two phases of the three-phase inverter outputs has been described. However, the current detector in the three phases of the three-phase inverter outputs. And a configuration including an offset compensation unit.

The block diagram of the electric motor control apparatus in a present Example. The figure which shows the division | segmentation range of the correction | amendment detection electric current during the inverter 3 driving | operation. 5 is a flowchart in the offset compensation unit of the first embodiment. 10 is a flowchart of an offset compensation unit according to the second embodiment. The block diagram of a common motor control device. General sample and hold circuit. The offset characteristic figure of a general current detector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Inverter 4 ... Electric motor 5a, 5b ... Current detector 9 ... Inverter control part 17a, 17b ... Offset compensation part Iu, Iw ... Detection current value Iu ', Iw' ... Correction detection current value

Claims (9)

An inverter for outputting a three-phase alternating current for driving the electric motor;
A current detector for detecting a current of at least two phases of the three-phase alternating current;
And an offset compensator that compensates an offset value included in the detected current value detected by each of the current detectors and outputs a compensation detected current value. ,
The offset compensation unit can be defined by dividing the entire range of the compensation detection current value that can be detected during inverter operation into a plurality of divisions, and includes storage means having a storage area corresponding to each division range,
Each time the operation of the inverter stops, one of the divided ranges is selected based on the magnitude and polarity of the maximum amplitude value before the inverter is stopped, and the inverter is stopped in the storage area related to the selected divided range. A control device for an electric motor which stores a subsequent detected current value and calculates an average value of the detected current values in all the stored storage areas as an offset value.   The data is extracted so that the number of data stored in each storage area is the same among the data in the detected current values stored in all the storage areas, and the extracted data is summed, and the sum is obtained. The motor control device according to claim 1, wherein an average value of detected current values in all storage areas is calculated by dividing the value by the total number of the extracted data.   2. The motor control device according to claim 1, wherein an average value of the latest detected current values for a plurality of times is calculated for each storage area, and an average value in the entire range is calculated from the average value in each storage area. .   4. The electric motor according to claim 3, wherein when calculating an average value in all the storage areas from an average value in the storage area, weighted moving average processing is performed in which different weights are applied to the average values in the storage areas. Control device.   The motor control device according to claim 1, wherein the storage unit includes a separate memory for each storage area.   6. The motor control apparatus according to claim 1, wherein the storage means is a nonvolatile memory.   An elevator apparatus comprising the motor control device according to any one of claims 1 to 6, wherein the motor drives a hoisting machine that travels a car. A current detector that detects at least two-phase current out of three-phase alternating current output from the inverter to the motor;
An offset compensation unit that compensates for an offset value included in a detected current value detected by each current detector, and a method for controlling an electric motor that performs current feedback control using an offset compensation unit,
The offset compensation unit can be defined by dividing the entire range of the compensation detection current value that can be detected during inverter operation into a plurality of divisions, and includes storage means having a storage area corresponding to each division range,
Each time the operation of the inverter stops, a selection step of selecting any one of the divided ranges based on the magnitude and polarity of the maximum amplitude value before the inverter stops,
A storage step of storing the detected current value after stopping the inverter in the storage area related to the selected divided range;
And an offset value calculating step of calculating an average value of detected current values in all storage areas stored in the storing step as an offset value. The selection step includes
A polarity determination step for determining the polarity of the compensation detection current value during inverter operation;
A maximum value update processing step of updating the maximum value of the amplitude value in the compensation detection current value;
9. The motor control method according to claim 8, wherein a division range determination step of determining a division range based on a polarity and a maximum amplitude value in the compensation detection current value is performed.

Images