JP2003088154A - Control method of ac motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect whether a rotating direction signal outputted by an encoder and a real rotating direction of an AC motor are different from a rotating direction command or not, and to correct them if they are different. SOLUTION: If both a first decision which decides the agreement of a rotating direction signal from a PE 16 with a rotating direction command, and a second decision which decides the agreement of a real rotating direction of an induction motor 17 with the rotating direction command, are normal, it is decided that both the rotating direction signal from the PE 16 and the phase sequence of the induction motor 17 are normal. If the first decision is abnormal and the second decision is normal, it is decided that the rotating direction signal from the PE 16 is abnormal. If both the first decision and the second decision are abnormal, it is decided that the phase sequence of the induction motor 17 is abnormal. If the first decision is normal and the second decision is abnormal, it is decided that both the rotating direction signal from the PE 16 and the phase sequence of the induction motor 17 are abnormal. If the rotating direction signal from the PE 16 is abnormal, the rotating direction signal is automatically corrected and, if the phase sequence of the induction motor 17 is abnormal, the phase sequence is automatically corrected. The automatically corrected results are stored in a memory and the induction motor 17 is driven according to the stored results.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC electric motor equipped with an encoder and operating at a variable speed, and detects whether or not the rotational direction signal of the encoder or the electric motor rotational direction is different from the command direction and corrects it when different. The present invention relates to a method of controlling an AC motor.

[0002]

2. Description of the Related Art FIG. 7 is a block circuit diagram showing a vector control circuit as an example of a power converter for variable speed driving an AC motor having a pulse encoder. This Figure 7
The outline of the operation of the vector control circuit shown in FIG. That is, the AC power from the AC power supply 12 is converted into AC power having a desired voltage and frequency by the inverter 13, and the induction motor 17 as an AC motor is operated at a variable speed. A pulse encoder 16 is coupled. The signal fed back from the pulse encoder 16 becomes the motor rotation speed ω _r by the speed calculator 19, and further becomes the rotor frequency ω ₂ by the rotor frequency calculator 20. On the other hand, the slip frequency calculator 6 inputs the T-axis current command value I _T ^* and the secondary magnetic flux command value φ ₂ ^* to obtain the slip frequency ω _sl . An angle Γ ₂ formed by the U-phase winding and the secondary magnetic flux of the motor is obtained by integrating ω _l, which is the sum of the slip frequency ω _sl and the rotor frequency ω ₂ , by the integrator 15. This Γ ₂ is used for coordinate conversion calculation in the first coordinate converter 10 and the second coordinate converter 11 which will be described later.

The current sensor 14 detects the primary side currents of the induction motor 17, and the second coordinate converter 11 detects the detected currents of the respective phases in the M-axis current detection value I parallel to the secondary magnetic flux of the primary current.
_M and T-axis current detection value I _T perpendicular to the secondary magnetic flux of the primary current
And convert to. The T-axis current regulator 8 has a T-axis current command value I
_T ^* and T axis enter the deviation between the current detection value I _T, T-axis voltage command value V as a result of the adjustment operation for the input deviation to zero
_{The T} ^* is output to the first coordinate converter 10, and the M-axis current controller 9 is output.
Similarly, M-axis current command value I _M ^* and M-axis current detection value I _M
Deviation is input, and the M-axis voltage command value V _M ^* is set as the result of the adjusting operation for reducing the input deviation to zero.
Output to. The first coordinate converter 10 obtains the phase voltage command values V _U ^* , V _V ^* , V _W ^* from these inputs and controls the inverter 13 to operate the induction motor 17 at a variable speed. Reference numeral 22 is a voltage sensor such as an instrument transformer, reference numeral 23 is a voltage detection circuit, and reference numeral 24 is a voltage indicator.

The above is the outline of the vector control, but since the vector control is not the subject of the present invention, its detailed description is omitted.

[0005]

[Problem to be Solved by the Invention] Pulse encoder 16
Is generally a phase A, so that the rotational speed, position, or direction of rotation of the induction motor 17 coupled to it can be detected.
Three pulses of B phase and Z phase are output. The A phase and the B phase have a phase difference of 90 degrees with each other, the rotation direction can be detected from the advance and delay of these two pulses, and the rotation speed can be determined from the count value of either one of the pulses per unit time. Can be detected. However, depending on the (a) pulse encoder, the phase of the A-phase pulse and the phase of the B-phase pulse in the rotation direction may be different.

(B) The phases of the A-phase pulse and the B-phase pulse may be inverted depending on the mounting direction. (c) Phase A and B
The phase of the A-phase pulse and the phase of the B-phase pulse are inverted due to incorrect wiring of the phase signal line. Due to such reasons, the pulse encoder 16
In some cases, the rotation direction detected in 1 and the actual rotation direction of the induction motor 17 do not match, which may cause the induction motor 17 to not operate normally.
Further, even if all of the mounting and wiring of the pulse encoder 16 are normal, if the phase sequence of the voltages applied to the induction motor 17 is incorrect due to incorrect wiring of the power circuit, or if the phases of the inverter 13 If the control of the operation sequence is not correct, the induction motor 17 may rotate in the direction opposite to the command rotation direction.

Further, although the pulse encoder 16 outputs a signal in a direction opposite to the command rotation direction, that is, a signal in an incorrect direction, the induction motor 17 causes the incorrect rotation direction signal command due to incorrect wiring or the like. If the pulse encoder 16 outputs a signal in the same direction as the command rotation direction as a result of rotation in the opposite direction, there is a risk that it will be determined to be normal operation, but it is not the intended command rotation direction. Therefore, if you want to continue operation, load 1
There is also the risk of damaging 8.

Therefore, an object of the present invention is to detect whether or not the rotation direction signal output from the encoder and the actual rotation direction of the AC motor are different from the command rotation direction, and if they are different, correct them.

[0009]

In order to achieve the above-mentioned object, a method of controlling an AC electric motor according to the present invention is an AC electric motor having a signal fed back from an optical pulse encoder or a magnetic encoder connected to the AC electric motor. In a method for controlling an AC electric motor for performing variable speed operation, a first judgment as to whether or not a rotation direction command signal obtained from the operation command signal of the AC electric motor and a feedback rotation direction signal obtained from the feedback signal match, A second judgment is made as to whether or not the rotation direction command signal and the actual rotation direction signal of the AC motor match, and from the results of the first judgment and the second judgment, the control of the rotation direction is normal or abnormal. To determine.

If both the first judgment and the second judgment are normal, it is judged that the phase sequence of the feedback rotation direction signal and the AC motor applied voltage are both normal, and the first judgment is abnormal and the second judgment is normal. If so, it is determined that the feedback rotation direction signal is abnormal. If both the first determination and the second determination are abnormal, it is determined that the phase sequence of the AC motor applied voltage is abnormal, and the first determination is normal and the second determination is If it is abnormal, it is determined that the feedback rotation direction signal and the phase sequence of the AC motor applied voltage are both abnormal.

When the feedback rotation direction signal is determined to be abnormal from the first and second determinations, the feedback rotation direction signal is automatically corrected and the phase sequence of the voltage applied to the AC motor is determined to be abnormal. If so, the phase sequence of the voltage applied to the AC motor is automatically corrected. The automatic correction of the feedback rotation direction signal and the automatic correction of the phase sequence of the AC motor applied voltage are stored, and the AC motor is operated in accordance with this storage.

Abnormality determination of the feedback rotation direction signal and automatic correction thereof according to the first determination and second determination, or abnormality determination of the AC motor and automatic phase sequence correction of applied voltage are performed off-line.

[0013]

1 is a flow chart showing a first embodiment of the present invention. In this flowchart, the rotation direction is given by the operation command signal (process 3
1) However, the feedback rotation direction signal output from the rotating pulse encoder 16 is detected (process 32).
To do. Whether or not the feedback rotation direction signal and the operation command signal are in the same direction is determined in a determination 45. If they are in the same direction (that is, yes), then the actual rotation direction of the induction motor 17 is detected (process 33). Then, it is judged at judgment 46 whether or not this motor actual rotation direction and the above-mentioned operation command signal are in the same direction. Judgment result is in the same direction (that is, yes)
If so, the pulse encoder 16 and the induction motor 17
Are all normal (process 34), which is case 1
(See FIG. 2).

If the result of determination 45 is NO, that is, if the feedback rotation direction signal and the operation command signal indicate different rotation directions, then the actual rotation direction of the induction motor 17 is detected (process 35), It is judged in the judgment 47 whether or not the actual rotation direction of the motor and the above-mentioned operation command signal are in the same direction.
If so, the pulse encoder 16 is abnormal (process 3
6). Therefore, it is necessary to perform processing such as replacing the output lines of the pulse encoder 16 (processing 37), which corresponds to Case 2 (see FIG. 3). This result is stored in the storage device (process 38).

Further, the judgment result in judgment 45 is NO, that is, the feedback rotation direction signal and the operation command signal are different from each other, and the judgment result in judgment 47 is NO, that is, the actual motor rotation direction and the operation command signal are different. If it is the direction, the induction motor 17 is abnormal (process 39). Therefore, the phase sequence of the voltage applied to the motor is changed (process 40),
This corresponds to case 3 (see FIG. 4). The result is stored in the storage device (process 41).

Further, the determination result of the determination 45 is YES, that is, the feedback rotation direction signal and the operation command signal are the same rotation direction, and the determination result of the determination 47 is no, that is, the actual motor rotation direction and the operation command signal are different. If directional, this is pulse encoder 16 and induction motor 17
Are abnormal (process 42). Therefore, the output line of the pulse encoder 16 is replaced and the phase sequence of the motor applied voltage is also changed (process 43), which corresponds to case 4 (see FIG. 5). This result is stored in the storage device (process 4).
4) Allow it.

FIG. 2 is a circuit diagram showing the connection when both the pulse encoder and the induction motor are normal.
This corresponds to case 1 in the flowchart described in 1.
FIG. 3 is a circuit diagram showing the connection when the pulse encoder is abnormal and the induction motor is normal, and corresponds to case 2 in the flowchart described in FIG. FIG. 4 is a circuit diagram showing the connection when the pulse encoder is normal and the induction motor is abnormal, and corresponds to case 3 in the flowchart described in FIG.

FIG. 5 is a circuit diagram showing the connection when the pulse encoder and the induction motor are both abnormal.
This corresponds to case 4 in the flowchart described in.
FIG. 6 is a block circuit diagram showing a second embodiment of the present invention. In FIG. 6, the output signal of a pulse encoder (hereinafter abbreviated as PE) 16 coupled to the induction motor 17 is transmitted through the speed / motor rotation direction detection circuit 51.
It becomes the motor rotation direction signal. The output signals of the current sensor 14 and the voltage sensor 22 for detecting the current / voltage of the induction motor 17 become a speed / motor rotation direction estimation signal via the speed / motor rotation direction estimation calculation circuit 52. By inputting these signals and the speed command signal with polarity to the PE / motor rotation direction judgment circuit 54, it is judged whether the rotation directions of the PE 16 and the induction motor 17 are normal to the speed command signal. . By storing this determination result in the storage element 55, it is not necessary to perform this determination each time.

When the output signal of the PE 16 is abnormal, the judgment result output from the storage element 55 is given to the speed / motor rotation direction detection circuit 51 via the detection rotation direction change circuit 56 to correct the output signal of the PE 16. However, when the rotation direction of the induction motor 17 is abnormal, the determination result output from the storage element 55 is given to the PWM (pulse width modulation) control circuit 50 via the output voltage command phase sequence changing circuit 57,
The phase sequence of the voltage applied to the induction motor 17 is changed. The second switch 61 is normally on the "normal time" side, and at this time, the deviation between the speed command signal with polarity and the speed / motor rotation direction signal or the speed / motor rotation direction estimation signal is speed controlled. Induction motor 17
To the desired speed.

Since it is not necessary to give a speed command signal to the PE / motor rotation direction judging circuit 54 to constantly judge the rotation directions of the PE and the motor, this judgment can be carried out offline at a necessary time. For that purpose, the circuit is configured so that the speed command signal and the forward / reverse rotation signal which are patterned in advance are given to the PE / motor rotation direction determination circuit 34 via the second switch 61 switched to the "offline" side. .

Note that the on / off of the third switch 62 and the switching of the fourth switch 63 are used to control the induction motor 17 in vector or open-loop V / F.
Either of the constant controls can be selected, but the detailed description thereof will be omitted. The present invention has been described by taking an induction motor as an example of an AC motor, but it goes without saying that the present invention can be applied to a synchronous motor.

[0022]

According to the present invention, the rotation direction of the AC motor coupled with the pulse encoder is different from the command rotation direction, and the rotation direction signal output from the pulse encoder is different from the command rotation direction. It is possible to detect whether or not the rotation direction is normal or abnormal without requiring a particularly large additional component because it is possible to detect whether or not the AC motor is controlled by using the sensor used for controlling the AC motor. . If the rotation direction is different from the command rotation direction, it can be corrected automatically.
It is also possible to obtain the effect of saving the trouble of performing the correction work each time.

[Brief description of drawings]

FIG. 1 is a flowchart showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing connection when both the pulse encoder and the induction motor are normal.

FIG. 3 is a circuit diagram showing the connection when the pulse encoder is abnormal and the induction motor is normal.

FIG. 4 is a circuit diagram showing the connection when the pulse encoder is normal and the induction motor is abnormal.

FIG. 5 is a circuit diagram showing connection when both the pulse encoder and the induction motor are abnormal.

FIG. 6 is a block circuit diagram showing a second embodiment of the present invention.

FIG. 7 is a block circuit diagram showing a vector control circuit as an example of a power converter that drives an AC electric motor equipped with a pulse encoder at a variable speed.

[Explanation of symbols]

6 Sliding frequency calculator 10 First coordinate converter 11 Second coordinate converter 12 AC power supply 13 Inverter 14 Current sensor 15 Integrator 16 PE (pulse encoder) 17 Induction motor as AC motor 19 Speed calculator 20 Rotor frequency calculator 31-44 processing 45-47 Judgment 50 PWM (pulse width modulation) control circuit 51 Speed / motor rotation direction detection circuit 52 Speed / motor rotation direction estimation calculation circuit 53 First switch 54 PE / motor rotation direction judgment circuit 55 Memory element 56 Detection rotation direction change circuit 57 Output voltage command phase order change circuit

Continued front page    F term (reference) 5H576 BB07 DD02 EE01 EE11 FF10                       GG02 GG04 HB01 LL07 LL13                       LL22 LL24 MM08

Claims (5)

[Claims] 1. A method for controlling an AC electric motor, wherein a variable speed operation of the AC electric motor is performed by a signal fed back from an optical pulse encoder or a magnetic encoder coupled to the AC electric motor, wherein a rotation obtained from an operation command signal of the AC electric motor. A first judgment is made as to whether or not the direction command signal and the feedback rotation direction signal obtained from the feedback signal match, and whether or not the rotation direction command signal and the actual rotation direction signal of the AC motor match. The method for controlling an alternating-current motor is characterized in that the control of the rotation direction is normal or abnormal based on the results of the first and second determinations. 2. The AC motor control method according to claim 1, wherein both the first judgment and the second judgment are normal, it is judged as normal, and the first judgment is abnormal and the second judgment is normal. For example, it is determined that the feedback rotation direction signal is abnormal, and if the first determination and the second determination are both abnormal, it is determined that the phase sequence of the voltage applied to the AC motor is abnormal, and the first determination is normal. 2. If the determination is abnormal, it is determined that both the feedback rotation direction signal and the phase sequence of the voltage applied to the AC motor are abnormal, and the AC motor control method. 3. The method for controlling an AC motor according to claim 1, wherein when the feedback rotation direction signal is determined to be abnormal from the first determination and the second determination, the feedback rotation is concerned. An AC motor characterized by automatically correcting the direction signal and automatically correcting the phase sequence of the voltage applied to the AC motor when the phase sequence of the voltage applied to the AC motor is determined to be abnormal. Control method. 4. The AC motor control method according to claim 1, wherein automatic correction of the feedback rotation direction signal and automatic correction of a phase sequence of a voltage applied to the AC motor are stored. Let
A method of controlling an AC electric motor, comprising: operating the AC electric motor according to the memory. 5. The method for controlling an AC electric motor according to claim 1, wherein the feedback rotation direction signal is determined to be abnormal by the first determination and the second determination and the AC correction is performed, or the AC is corrected. A method for controlling an alternating-current motor, characterized in that an abnormality determination of the electric motor and a phase sequence automatic correction of an applied voltage are performed off-line.