JP2007252119A - Ac motor driving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an AC motor driving system suitable for a plurality of AC motors, mutually connecting output shafts of the AC motors, and driving a single load. <P>SOLUTION: An activation instruction and a speed instruction are applied to an upper level controller 11. The upper level controller 11 reads a rotor speed estimation ω<SB>R</SB><SP>#</SP>of an induction motor 3 at a predetermined elapsed time in accordance with the instructions while motor controllers 2, 4, 6 operate in a rotation mode, and compares the rotor speed estimation ω<SB>R</SB><SP>#</SP>with a speed instruction value ω<SP>*</SP>. If a difference between them exceeds a predetermined value, it determines that the motor controller 2 and the induction motor 3 abnormally operate, a gate blocking instruction is issued to a PWM inverter 24, the induction motor 3 freely runs once by blocking an output from the PWM inverter 24, and the motor controller 2 and the induction motor 3 restart by issuing a restart instruction to the motor controller 2. The problem that the total AC motor driving system becomes inoperative due to an increase in the difference is overcome. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention uses a plurality of AC motors and a plurality of motor control devices for variable speed control of the AC motors by a speed sensorless vector control method, and the same timing, the same amount of speed command values, etc. are assigned to each motor control device. The present invention relates to an AC motor drive system that includes a host control device that provides power and connects the output shafts of the motors to drive a load.

In this type of conventional AC motor drive system, each AC motor that drives a load by connecting output shafts to each other is individually provided with a speed sensor. In each motor controller, the speed command value from the host controller is By performing vector control based on the detected rotor speed value from the speed sensor, the voltage and current supplied to the motor from the motor control device, and the electric constant of the motor, each corresponding AC motor is operated in a desired manner. Was in control of the state.
Japanese Patent Laid-Open No. 11-150997

  In the above-described conventional AC motor drive system, each AC motor is individually provided with a speed sensor, the speed sensor is relatively expensive, and depending on the connection method of the output shaft of each AC motor, for example, It is necessary to provide a hollow structure speed sensor that can be mounted on the output shaft of the electric motor, and there is a problem that it is more complicated and expensive.

  An object of the present invention is to provide an AC motor drive system capable of controlling each of AC motors whose output shafts are connected to each other in a desired operation state using a speed sensorless vector control method of the AC motor.

The first invention uses a plurality of AC motors and a plurality of motor control devices for variable speed control of the AC motors by a speed sensorless vector control method, and the same timing and the same amount of speed for each motor control device. In an AC motor drive system that includes a host controller that gives command values and the like, and that connects the output shafts of the motors to drive a load,
The host controller compares the estimated speed value of each AC motor obtained from each motor controller with the speed command value, and outputs from the motor controller whose difference is greater than a preset value. After the motor is shut off, the motor control device is restarted.

2nd invention is the said AC motor drive system,
In the host controller, the torque current command value of each AC motor obtained from each motor controller is compared with the torque current command value in other motor controllers or the average value thereof, and the difference is based on a preset value. After the output from the increased motor control device is cut off, the motor control device is restarted.

3rd invention is the said AC motor drive system,
In the host controller, the rotor speed estimated value of each AC motor obtained from each motor controller is compared with the rotor speed estimated value or the average value in other motor controllers, and the difference is set in advance. After the output from the motor control device that has become larger than the value is cut off, the motor control device is restarted.

A fourth invention is the AC motor drive system of the first to third inventions,
After shutting off the output from the motor control device, the estimated value of the rotor speed in the other motor control device or the average value thereof, or the torque current command value in the other motor control device or the average value thereof in the motor control device The value is rewritten in advance and restarted.

  According to the present invention, when performing speed sensorless vector control on an AC motor, in particular, the undesirable behavior of each AC motor due to an arithmetic error in the estimated rotor speed of the motor that occurs when the motor rotates at a low speed. Therefore, in the AC motor drive system of the present invention, the speed sensor conventionally provided for each AC motor can be omitted, and as a result, the cost of the entire system can be reduced.

  FIG. 1 is a circuit configuration diagram of an AC motor drive system showing an embodiment of the present invention. In this figure, reference numeral 2 denotes an electric motor control device for variable speed control of an AC motor 3 by a speed sensorless vector control method, and reference numeral 4 denotes an AC motor. An electric motor control device for variable speed control of the electric motor 5 by the speed sensorless vector control method, an electric motor control device 6 for variable speed control of the AC electric motor 7 by the speed sensorless vector control method, and 11-16 are electric motor control devices 2, 4 and 6, respectively. As shown in the figure, the output shafts of the three AC motors 3, 5, 7 are connected to each other as shown in the figure. A load 8 such as an industrial machine such as a crane is driven.

  FIG. 2 is a partial detailed circuit configuration diagram of the AC motor drive system shown in FIG. 1, and this figure shows any one of the host control devices 11 to 16, the motor control device 2, and the induction motor as the AC motor 3. An example of the configuration of the related part is shown. This motor control device 2 includes a speed regulator 21, a current regulator 22, a vector rotator 23, a PWM inverter 24, a magnetic flux command unit 25, a current calculator 26, a vector rotator 27, and a current detection. It comprises a calculator 28, a vector rotator 29, a voltage detector 30, a slip frequency calculator 31, an adder calculator 32, an integrator 33, and a primary frequency estimator 34. The motor control devices 4 and 6 shown in FIG. 1 have the same configuration as that of the motor control device 2 shown in FIG. 2, and these components are formed by using well-known techniques.

The primary frequency estimator 34 shown in FIG. 2 detects the current flowing from the PWM inverter 24 to the induction motor 3 by the current detector 28 in order to derive the primary frequency estimated value ω ₁ ^# of the induction motor 3. voltage values and current detection values I _T of the torque shaft of the induction motor 3 by a vector rotator 27 and the value obtained by coordinate transformation to the current detection value I _M of the magnetization axis, the voltage applied to the induction motor 3 from the PWM inverter 24 The value detected by the detector 30 and coordinate-converted by the vector rotator 29 to the detected voltage V _T of the torque shaft of the induction motor 3 and the secondary magnetic flux of the induction motor 3 obtained from the magnetic flux commander 25. The following formulas 1 to 3 based on the command value φ ₂ ^* and the electrical constant of the induction motor 3 are used.
(Equation 1)
V _T = r ₁ · I _T + ω ₁ ^# · Lσ · I _M + ω ₁ ^# {φ ₂ ^* / (σ + 1)}
Here, r ₁ is a primary resistance of the induction motor 3, Lσ is a leakage inductance (converted to the stator side) of the induction motor 3, and φ ₂ ^* / (σ + 1) is an induced voltage coefficient of the induction motor 3.

That is, in the speed sensorless vector control of the induction motor 3, focusing on the fact that the torque axis component V _T of the terminal voltage of the induction motor 3 is substantially proportional to the rotor speed ω _R of the induction motor 3 from the above equation 1, voltage detection The terminal voltage taken in by the electric machine 30 is calculated using the electric constant of the electric motor, and the rotor speed of the induction motor 3 is estimated.

Therefore, when the above equation 1 is modified, the following equation 2 is obtained.
(Equation 2)
^{_{ω 1 # = (V T -r}} 1 · I T -ω 1 # · Lσ · I M) / K
Here, K is {φ ₂ ^* / (σ + 1)}.

Further, in order to perform the calculation of the above formula 2 by a discrete value calculation using a microcomputer, the approximate calculation of the following formula 3 is performed.
(Equation 3)
ω ₁ ^# (0) = {V _T −r ₁ · I _T −ω ₁ ^# (1) · Lσ · I _M } / K
Here, ω ₁ ^# (0) represents the current estimated value, and ω ₁ ^# (1) represents the previous estimated value.

That is, when the discrete time (calculation cycle) is sufficiently short, ω ₁ ^# (0) ≈ω ₁ ^# (1) is established, and thus the above formula 2 and formula 3 are equal.

In the slip frequency calculator 31 shown in FIG. 2, the torque axis current detection value _IT and the magnetization axis current detection value I _M obtained by the vector rotator 27 and the electric constant of the induction motor 3 are obtained. Based on the above, the slip frequency calculation value ω _S ^# is derived.

Accordingly, adders 32 induction is the rotor speed estimate value of the electric motor 3 omega _R ^# is obtained from the induction motor 3 in the rotational speed of the rotor speed estimation value omega _R ^# obtained at zero speed near the induction motor It is known that the calculation error increases because the value related to the primary resistance r ₁ of 3 and the detection error of the voltage and current to the motor become relatively large.

As a result, the torque current command value I _T ^* which is the adjustment calculation result in the speed regulator 21 is also greatly deviated from the appropriate value, and this deviation further falls into a vicious circle of error expansion, making the entire AC motor drive system inoperable. There was a fear.

  In the following, referring to the flowcharts of FIGS. 3 to 8 for explaining the embodiment of the present invention, the motor control device 2 has an estimation error in the operation of the AC motor drive system that has solved the above-mentioned problems. A case will be described as an example.

  3 is a flowchart for explaining the operation of the host control apparatus 11 shown in FIG. 1 showing the first embodiment of the present invention.

A start command and a speed command ω are instructed to the host controller 11, and the same speed command value ω ^{* as} the operation command is issued to the motor control devices 2, 4 and 6 at the same timing in accordance with these commands. While the induction motors 3, 5, and 7 are rotating, the estimated rotor speed value ω _R ^# of the induction motor 3 is read at every predetermined elapsed time (step S11) and compared with the speed command value ω ^{* at} this time ( In step S12), if the difference is less than 10%, for example, it is determined that the motor control device 2 and the induction motor 3 are operating normally, and waits until the next elapsed time.

On the other hand, when the difference exceeds 10% in step S12, it is determined that the motor control device 2 and the induction motor 3 are operating abnormally, and a gate cutoff command is issued to the PWM inverter 24 (step S13). The induction motor 3 is temporarily free run by shutting off the output of the motor, and thereafter the rotor speed estimation value ω _R ^# of the induction motor 3 is reset, and the gate shutoff command is released to the motor control device 2. By issuing a restart command (step S14), the motor control device 2 and the induction motor 3 are brought into the operating state again, and the entire AC motor driving system is not disabled due to the increase in the difference. .

  FIG. 4 is a flow chart for explaining the operation of the host controller 12 shown in FIG. 1 showing the second embodiment of the present invention.

A start command and a speed command ω are instructed to the host control device 12, and the same speed command value ω ^{* as} the operation command is issued to the motor control devices 2, 4, 6 at the same timing in accordance with these commands. While each of the induction motors 3, 5, and 7 is rotating, the rotor speed estimated value ω _R ^# of the induction motor 3 and the torque current command value I _T ^* that is the adjustment calculation result in the speed regulator 21 at every predetermined elapsed time ^. (Step S21) and compared with the speed command value ω ^{* at} this time (step S22). If the difference is, for example, less than 10%, it is determined that the motor control device 2 and the induction motor 3 are operating normally. Then, the average value of the value read in step S21 and each value in the other machine, that is, the motor control device 4 or the motor control device 6 is obtained and stored (step 26).

On the other hand, when the difference exceeds 10% in step S22, it is determined that the motor control device 2 and the induction motor 3 are operating abnormally, and a gate cutoff command is issued to the PWM inverter 24 (step S23). The induction motor 3 is once free-runned by shutting off the output of the motor, and at this time, the speed controller 21 of the motor controller 2 does not have a large deviation between the speed command value ω ^* and the estimated speed value ω _R ^#. Rotor speed estimation value ω _R ^# , torque current command value I _T ^* obtained from one of the other machines, that is, motor control device 4 or motor control device 6, or rotor obtained from motor control devices 4 and 6 speed estimation value omega _R ^#, forcibly rewritten to the respective average torque current command value I _T ^* (step S24), and then, is released with a gate blocking instruction restart command By issuing (step S25), and by the electric motor control unit 2 and the induction motor 3 is again operating conditions, the entire AC motor drive system in accordance with the enlargement of the difference is to eliminate falling into inoperable.

  FIG. 5 is a flow chart for explaining the operation of the host controller 13 shown in FIG. 1 showing the third embodiment of the present invention.

A start command and a speed command ω are instructed to the host control device 13, and the same speed command value ω ^{* as} the operation command is issued to the motor control devices 2, 4, and 6 at the same timing in accordance with these commands. While each of the induction motors 3, 5, and 7 is rotating, a torque current command value I _T ^* that is an adjustment calculation result in the speed regulator 21 of the induction motor 3 is read at every predetermined elapsed time (step S31). Torque current command value I _T ^* is compared with the average value of torque current command values I _T ^* obtained from the other machines, that is, the motor control device 4 and the motor control device 6 (step S32). If it is less than%, it is determined that the motor control device 2 and the induction motor 3 are operating normally, and the values read in step S31 and the values in the other devices, that is, the motor control device 4 or the motor control device 6, respectively. Storing the average value (step 35).

On the other hand, when the difference exceeds 10% in step S32, it is determined that the motor control device 2 and the induction motor 3 are operating abnormally, and a gate cutoff command is issued to the PWM inverter 24 (step S33). The induction motor 3 is temporarily free run by shutting off the output of the motor, and thereafter the rotor speed estimation value ω _R ^# of the induction motor 3 is reset, and the gate shutoff command is released to the motor control device 2. By issuing a restart command (step S34), the motor control device 2 and the induction motor 3 are put into an operation state again, and the entire AC motor drive system is prevented from being disabled as the difference increases. .

  FIG. 6 is a flow chart for explaining the operation of the host controller 14 shown in FIG. 1 showing the fourth embodiment of the present invention.

A start command and a speed command ω are instructed to the host controller 14, and an operation command and the same speed command value ω ^* are issued to the motor control devices 2, 4, and 6 at the same timing according to these commands. While each of the induction motors 3, 5, and 7 is rotating, the rotor speed estimated value ω _R ^# of the induction motor 3 and the torque current command value I _T ^* that is the adjustment calculation result in the speed regulator 21 at every predetermined elapsed time ^. (Step S41), and the torque current command value I _T ^{* at} this time is compared with the average value of the torque current command value I _T ^* obtained from the other machine, that is, the motor control device 4 and the motor control device 6 ( In step S42), if the difference is less than 10%, for example, it is determined that the motor control device 2 and the induction motor 3 are operating normally, and the value read in step S41 and the other device, that is, the motor control device 4 or the motor control. Storing the average value of the respective values at location 6 (step 46).

On the other hand, when the difference exceeds 10% in step S42, it is determined that the motor control device 2 and the induction motor 3 are operating abnormally, and a gate cutoff command is issued to the PWM inverter 24 (step S43). In this case, the induction motor 3 is once free-runned by shutting off the output of the motor. At this time, the speed controller 21 of the motor control device 2 has a difference that the difference between the torque current command value I _T ^* and the average value is not large. Rotor speed estimation value ω _R ^# , torque current command value I _T ^* obtained from one of the motors, that is, motor control device 4 or motor control device 6, or rotation speed estimation obtained from motor control devices 4 and 6 value omega _R ^#, forcibly rewritten to the respective average torque current command value I _T ^* (step S44), then, as to release the gate opening command, restarts the finger By emitting (step S45), and the electric motor control unit 2 and the induction motor 3 is again operating conditions, the entire AC motor drive system in accordance with the enlargement of the difference is to eliminate falling into inoperable.

  FIG. 7 is a flow chart for explaining the operation of the host controller 15 shown in FIG. 1 showing the fifth embodiment of the present invention.

A start command and a speed command ω are instructed to the host controller 15, and the same speed command value ω ^{* as} the operation command is issued to the motor control devices 2, 4 and 6 at the same timing in accordance with these commands. While each of the induction motors 3, 5, and 7 is rotating, the estimated rotor speed value ω _R ^# of the induction motor 3 is read at every predetermined elapsed time (step S51). At this time, the estimated rotor speed value ω _R ^# and The average value of the rotor speed estimated value ω _R ^# obtained from the other machine, that is, the motor control device 4 and the motor control device 6 is compared (step S52), and if the difference is less than 10%, for example, this motor It is determined that the control device 2 and the induction motor 3 are operating normally, and an average value between the value read in step S51 and the value in the other device, that is, the motor control device 4 or the motor control device 6, is obtained and stored (step 55). )

On the other hand, when the difference exceeds 10% in step S52, it is determined that the motor control device 2 and the induction motor 3 are operating abnormally, and a gate cutoff command is issued to the PWM inverter 24 (step S53). The induction motor 3 is temporarily free run by shutting off the output of the motor, and thereafter the rotor speed estimation value ω _R ^# of the induction motor 3 is reset, and the gate shutoff command is released to the motor control device 2. By issuing a restart command (step S54), the motor control device 2 and the induction motor 3 are put into an operation state again, and the entire AC motor drive system is prevented from being disabled as the difference increases. .

  FIG. 8 is a flow chart for explaining the operation of the host controller 16 shown in FIG. 1 showing the sixth embodiment of the present invention.

A start command and a speed command ω are instructed to the host controller 16, and in accordance with these commands, the motor control devices 2, 4, 6 are each issued with the same speed command value ω ^{* as} the operation command at the same timing, and the induction motor While each of 3, 5 and 7 is rotating, it reads the estimated rotor speed value ω _R ^# of the induction motor 3 and the torque current command value I _T ^* which is the adjustment calculation result in the speed regulator 21 at every predetermined elapsed time. (Step S61) The rotor speed estimated value ω _R ^{# at} this time is compared with the average value of the rotor speed estimated value ω _R ^# obtained from the other machine, that is, the motor control device 4 and the motor control device 6 ( In step S62), if the difference is less than 10%, for example, it is determined that the motor control device 2 and the induction motor 3 are operating normally, and the value read in step S61 and the other device, that is, the motor control device 4 or the motor control. With device 6 The average value of each value is obtained and stored (step 66).

On the other hand, when the difference exceeds 10% in step S62, it is determined that the motor control device 2 and the induction motor 3 are operating abnormally, and a gate cutoff command is issued to the PWM inverter 24 (step S63). In this case, the induction motor 3 is once free-runned by shutting off the output of the motor. At this time, the speed controller 21 of the motor control device 2 is the other machine in which the deviation between the estimated speed value ω _R ^# and the average value is not large. That is, the estimated rotor speed value ω _R ^# , the torque current command value I _T ^* obtained from either the motor controller 4 or the motor controller 6, or the estimated rotor speed obtained from the motor controllers 4, 6. value omega _R ^#, forcibly rewritten to the torque current command value I _T ^* each average value (step S64), then, as to release the gate blocking instruction, the restart command (Step S65) by, in the electric motor control unit 2 and the induction motor 3 is again operating conditions, the entire AC motor drive system in accordance with the enlargement of the difference is to eliminate falling into inoperable.

  In the description of the embodiment of the present invention based on the flowcharts of FIG. 3 to FIG. 8 described above, an example with three or more units is performed. However, in FIG. 4 to FIG. It is only necessary to perform processing based on values read from other machines.

Circuit diagram of AC motor drive system showing an embodiment of the present invention Partial detailed circuit configuration diagram of FIG. Operation flow chart of AC motor drive system showing first embodiment of this invention Operation flow diagram of AC motor drive system showing second embodiment of this invention Operation flow diagram of AC motor drive system showing third embodiment of the present invention Operation flow diagram of AC motor drive system showing fourth embodiment of the present invention Operation flow diagram of AC motor drive system showing fifth embodiment of the present invention. Operation flow diagram of AC motor drive system showing sixth embodiment of the present invention.

Explanation of symbols

  2, 4, 6 ... motor controller, 3, 5, 7 ... AC motor, 8 ... load, 11-16 ... host controller, 21 ... speed regulator, 22 ... current regulator, 23 ... vector rotator, 24 ... PWM inverter, 25 ... magnetic flux command device, 26 ... current calculator, 27 ... vector rotator, 28 ... current detector, 29 ... vector rotator, 30 ... voltage detector, 31 ... slip frequency calculator, 32 ... addition Arithmetic unit, 33... Integrator, 34.

Claims (4)

High-order control using a plurality of AC motors and a plurality of motor control devices for variable speed control of the AC motors by a speed sensorless vector control method, and giving the same timing, the same amount of speed command values, etc. to each motor control device In an AC motor drive system comprising a device and driving a load by connecting output shafts of the motors to each other,
The host controller compares the estimated speed value of each AC motor obtained from each motor controller with the speed command value, and outputs from the motor controller whose difference is greater than a preset value. The AC motor drive system is characterized in that the electric motor control device is restarted after being shut off. High-order control using a plurality of AC motors and a plurality of motor control devices for variable speed control of the AC motors by a speed sensorless vector control method, and giving the same timing, the same amount of speed command values, etc. to each motor control device In an AC motor drive system comprising a device and driving a load by connecting output shafts of the motors to each other,
In the host controller, the torque current command value of each AC motor obtained from each motor controller is compared with the torque current command value in other motor controllers or the average value thereof, and the difference is based on a preset value. An AC motor drive system characterized by restarting the motor control device after the output from the increased motor control device is shut off. High-order control using a plurality of AC motors and a plurality of motor control devices for variable speed control of the AC motors by a speed sensorless vector control method, and giving the same timing, the same amount of speed command values, etc. to each motor control device In an AC motor drive system comprising a device and driving a load by connecting output shafts of the motors to each other,
In the host controller, the rotor speed estimated value of each AC motor obtained from each motor controller is compared with the rotor speed estimated value or the average value in other motor controllers, and the difference is set in advance. A control method for an AC motor drive system, comprising: shutting off an output from a motor control device that has become larger than a value, and then restarting the motor control device. In the AC motor drive system according to any one of claims 1 to 3,
After shutting off the output from the motor control device, the estimated value of the rotor speed in the other motor control device or the average value thereof, or the torque current command value in the other motor control device or the average value thereof in the motor control device. The AC motor drive system is characterized in that the value is rewritten in advance and restarted.

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