JPS6188793A - Field controller of induction motor - Google Patents

Abstract

PURPOSE:To control so that the responding time of a magnetic flux becomes shortest by using the primary delay element equivalent to the delay by the secondary time constant of the cause of delay of a response of the magnetic flux in a simulated manner to from a closed loop. CONSTITUTION:A field instructing circuit 1 outputs a field command phiS. The primary delay element 3 has the primary delay equivalent to the delay by the secondary time constant T2 of an induction motor, and outputs a signal phiX. A differential amplifying element 4 amplifies the difference between the output phiX of the element 3 and the field command phiS by K times. An adding element 5 with limit adds the output phiD of a differential amplifying element 4 and the field command phiS, limits the upper and lower limits, and outputs an output phiO to the primary delay element 3 and the field output circuit 2. The circuit 2 outputs a field command to an induction motor in response to phiO.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a field control device for an induction motor that maintains an orthogonal relationship between a torque component current and a field component current of the induction motor and controls them independently.

[Conventional technology]

In vector control of an induction motor, the magnetic flux generated in response to the field command follows the induction motor's second-order time constant (second-order delay), so in order to speed up the response of this magnetic flux,
In the conventional field control device, as shown in FIG. 4, the differential output ΦD from the differential element 22 (T2 is a secondary time constant) is added to the field command S of the field command circuit 21 to reduce the delay in magnetic flux response. The field command output circuit 26 outputs the differential compensation corresponding to the following.

[Problem that the invention seeks to solve]

However, in this conventional field control device, when the field command ΦS changes quickly or when the secondary time constant T2 is large, the field command ΦB saturates (overflows in the case of digital processing) and cannot make sufficient correction. Therefore, there is a problem that the desired responsiveness cannot be obtained, and there is also a problem that if the change in the field command is slowed down to eliminate the saturation, the coordination of the field control is impaired.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a field control device for an induction motor that controls the magnetic flux response time of the field of the induction motor to be the shortest.

[Failure to solve the problem]

The present invention takes into account the saturation of the field component output by total heat by creating a closed-loop configuration by pseudo-using a first-order delay element equivalent to the delay due to the second-order time constant, which is the cause of the delay in magnetic flux response. This system automatically controls the response to be the shortest at the amount determined by the limit value of the field component output without causing any disturbance, and is a first-order lag element equivalent to the delay due to the second-order time constant of an induction motor. , a difference amplification element that amplifies the difference between the output of the first-order lag element and the field current command or the field command; and a difference amplification element that amplifies the difference between the output of the first-order lag element and the field current command or the field command; The present invention is characterized in that it includes a restriction addition element that performs a lower limit restriction and outputs the output to the first-order lag element and as a field component current command output or field command output of the induction motor.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a field control device for an induction motor according to the present invention.

The field suppression device for the induction motor of this embodiment has a first-order delay element 6 equivalent to the delay due to the second-order time constant T2 of the field induction motor.
Then, add the difference amplification element 4 that doubles the difference between the output ΦX of this first-order lag element 6 and the field command Φ8, and the output ΦD of this difference amplification element 4 and the field command Φ3, and then It is comprised of a limiting addition element 5 that performs lower limit limiting (in this embodiment, the upper limit is 200% and the lower limit is 0%) and outputs the output Φ0 to the first-order delay element 6 and the field output circuit 2.

Next, an example of the operation of this embodiment will be explained with reference to the time chart of FIG.

Figure 2 shows the time t when the field command is applied. from zero to 100 (', o
) Since the output ΦX of the first-order lag element 6 is initially zero, the differential amplification element 4 outputs an output ΦD that is twice the field command ΦS. . From the limit addition addition element 5, the field command Φ8 and the output Φ of the differential amplification element 4 are output. is added, and the limit value 200 ('
, 10). is output. -The output ΦX of the second-order lag element 6 inputs the output Φ0 of the limited addition addition element 5 and rises with a first-order lag.

Then, time t, (: -T2 0.6 in 0.5
93T2), the output ΦX of the first-order lag element 3 is the field command ΦS
When it becomes equal to , the output ΦD of the differential amplification element 4 becomes zero, the operation is completed, and the response time of the magnetic flux is controlled to be the shortest.

The field component current output circuit 12 (composed of a first-order delay element 16, a differential amplification element 14, and a limit addition addition element 15) operates in the same manner as in FIG.

〔Effect of the invention〕

As explained above, the present invention uses a pseudo first-order delay element equivalent to the delay due to the second-order time constant, which is the cause of the delay in magnetic flux response, to create a closed-loop configuration, so that the field component output @
(2) It has the effect that the response of the magnetic flux becomes the shortest at l, which is determined by the limit value of the field component output, without considering J as the total heat.

[Brief explanation of the drawing]

FIG. 1 shows the field 1fi'J I of the induction electric reed according to the present invention.
A block diagram of one embodiment of the wholesale device, the second section is a time chart showing the output of each part of FIG. 1, and FIG. 6 is a block diagram of another implementation of the field side m device of the induction motor according to the present invention. ,
FIG. 4 is a block diagram of a conventional example of a field control device for an induction motor. 5.15: Limit addition addition element, 4.14: Differential amplification element, 3.13: First-order lag element, 2: Field command output circuit, 12: Field current command output circuit. Patent applicant Yaskawa Electric Co., Ltd. +, Mi//+: Figure 1 Figure 3

Claims (1)

[Claims] In a field control device for an induction motor that maintains an orthogonal relationship between a torque component current and a field component current of the induction motor and controls them independently, a delay element, a difference amplification element that amplifies the difference between the output of the first-order delay element and the field current command or the field command, and adds the output of the difference amplification element and the field component current command or the field command; An induction motor characterized in that it is provided with a limiting addition element that limits the upper and lower limits of this and outputs it to the first-order lag element and outputs it as a field component current command output or field command output of the induction motor. Field control device.