JPS622873A - Home position stop controller of induction motor - Google Patents

Abstract

PURPOSE:To shorten a home position stopping time by resetting the integrating term of a speed loop during a period of switching to a position loop after arriving at an orient speed. CONSTITUTION:A 3-phase AC power source 1 is converted through a rectifier 2, a filter 3 and ain inverter 4 to the AC voltage of variable frequency to thereby drive an induction motor 5 of a load. This controller has a speed detector 6, a speed detector 9, a pulse oscillator 7, a pulse detector 10, a speed instructing circuit 8, a slip frequency calculator 11, a voltage/pulse converter 12, a voltage instructing circuit 13, a waveform forming circuit 14, an output voltage detector 15 and a PWM control circuit 16 to control a home position. In this case, a switch SW for switching the calculator 11 to a PI calculator 11A or a P calculator 11B is provided. Thus, the integrating term of a speed loop is reset during a period of switching to a position loop after arriving at an orient speed at the decelerating time after a home position stop/start command is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixed position stop control method for an induction motor driven by an inverter device, and is particularly aimed at stabilizing the fixed position stopping operation.

"Prior Art" Conventionally, there has been a method shown in FIG. 4 to explain this type of control method. In Fig. 4, (1) is a three-phase AC power supply, (2) is composed of diodes, cyristors, etc. (1) is a rectifier circuit that rectifies the alternating current supplied from rectifier circuit (2), (3) is a filter that smoothes the DC voltage of rectifier circuit (2), (0 is composed of switching elements such as transistors, and (5) is an inverter device that converts a DC voltage into a pulse width modulated (hereinafter referred to as Pwx) variable frequency AC voltage;
4) Induction motor (hereinafter referred to as motor) that serves as the load
, (8) is a speed detector that detects the rotation speed of the electric motor (5), and (7) is a mark pulse Pa generated every rotation of the electric motor (5), and an electric motor between the mark pulse and the next mark pulse. This is a pulse oscillator that generates an A-phase pulse P^ indicating the rotational position of a(5) and a B-phase pulse Lumi that is delayed by 90%.The A-phase and B-phase pulses are For example, 512 items are shipped each.

Therefore, (8) is a speed command circuit that provides a speed reference value as a speed command for the electric motor (5), and (9) is a speed detector (
8) A speed detection circuit that estimates the rotational speed of the electric motor (5) based on the signal from the pulse transmitter (7).
mark pulses P- and A sent out from ).

A pulse detection circuit outputs a current rotational position detection signal PP for detecting a position error based on the count of B-phase pulses P^ and PB. A slip frequency calculator that calculates the slip ratio S, (12) is the sum of the slip ratio S of the slip frequency calculator (11) and the estimated speed value H of the speed detection circuit (8).
Pulse P with a frequency proportional to the frequency command f from Tohi S
A voltage/pulse converter that outputs G, (13) is a frequency command f0 of the voltage/pulse converter (12) to the motor (5)
a voltage command circuit that outputs a voltage command Vo corresponding to the voltage frequency characteristic of (14), a waveform forming circuit that receives the pulse po and the voltage command VO and outputs a signal vr indicating a reference voltage waveform for PWM control; (15) is a voltage detection circuit that detects the signal Vl indicating the output voltage of the inverter device (4), and (1B) is an inverter device that detects the signal Vl indicating the output voltage of the inverter device (4). This is a PWM control circuit that outputs a signal Sl for operating the device (4).

Next, referring to the waveform diagram shown in Fig. 5, the rotating electric motor (
The operation of stopping 5) at a fixed position will be explained. Fifth
In the figure, the solid line shown in (a) is the speed command, the broken line is the estimated speed value, (b) is the fixed position stop command, and (C)
(d) is a speed attainment signal, and mark pulse P-1 (e), which is output one pulse per rotation of the motor, is an in-position signal indicating completion of stopping the motor (5) at a fixed position.

At time t1, when a fixed position stop command is input, the speed command circuit (8) changes the speed command from hir.
rp error). At time t2, the speed detector (9) detects that the rotational speed of the electric motor a (5) has reached the speed command V r l.
detects it and outputs a speed reaching signal.

Therefore, when the mark pulse P- of the pulse oscillator (7) is output at time t3, the pulse detection circuit (lO) detects A,
Start counting B-phase pulses, and at time t4, electric motor a (5
) has reached about 1800 points before the target stopping point, so the speed command circuit (8) transfers the speed command to h2 at the creep speed (approximately 20 to 30 rpm) as the second speed. At time t5, the electric motor (5
) reaches approximately 30 degrees before the target stopping point, the control loop consisting of the speed command circuit (8) to the waveform forming circuit (14) is switched from the speed loop to the position loop, and the speed command The position of the electric motor (5) reaches the target stopping point at time t6, which is the speed determined by the gain of the position loop, so an imposition signal is output and the electric motor (5)
) has stopped at the target stopping point.

FIG. 3(a) shows the calculation method of the slip frequency calculator (11). In the figure, KP is speed deviation=hi, -
H is multiplied by the proportionality constant (proportional term), and Kl/
S is a value obtained by multiplying the speed deviation by an integral constant and integrating the past value (integral term), and proportional + integral control (PI sub-control) is performed as in the normal speed control method.

[Problem to be Solved by the Invention 1] In the conventional control system as described above, PI sub-control is always performed in the speed loop, so when an electric motor is used for the main spindle of a machine tool, When GO' is very large (for example, 5 times or more) compared to the motor's GO', the acceleration/deceleration time becomes longer, the PI sub-control integral term increases, and even after reaching the speed, the speed overshoot decreases. Particularly in the fixed position stopping function which requires smooth operation, there is a problem in that a sufficiently smooth stopping operation cannot be achieved, as shown by the broken line in FIG. 5 (11).

This invention was made in order to solve the problems of the conventional ones as described above, and it makes it possible to smoothly stop the electric motor in a fixed position, thereby increasing the orientation speed, and as a result, it is possible to increase the orientation speed. The purpose of this invention is to provide a control method that shortens the time required for stopping.

``Means for Solving the L Problem'' The fixed position stop control method for an induction motor according to the present invention has two speed operations (normal speed Hiro - Orient speed Hirrl and Orientation speed 1/r, % creep speed Hrl), for the purpose of preventing speed overshoot reduction, the period t2 to t5 from when the orientation speed is reached until switching to the position loop.
The integral term of the speed loop is reset, that is, slip control is performed using only the proportional term.

[Operation] When a fixed position stop command is input to a motor rotating at a given speed, it will operate smoothly without speed overshoot, regardless of the magnitude of GD2 on the machine side, which is the load of the motor.
The shaft of the electric motor can be stopped at the target stopping point.

[Embodiment] FIG. 1 is a block diagram illustrating a fixed position stop control system according to an embodiment of the present invention. The same reference numerals as in FIG. The operation method of the P operation unit (IIB) can be changed to the operation method of the P operation unit (IIB) by switching to the operation circuit (IIA) or the P operation circuit (IIB) as shown in Figure 3 (b).
As a means of reducing only the P (proportional) term in the figure, IC! Section A) is being reset.

Next, the operation will be explained with reference to the waveform diagram shown in FIG. In FIG. 2, (a) to (e) show signals in the same portions as those shown in FIG.

The operation from time t1 to t2 is the same as that described in FIG.
t5 corresponds to the present invention, and the operation is the same as the explanation in FIG. 5, but at this time, by setting the switch SW to the 0 position B, the speed loop
As shown in the broken line in Fig. 2(a), the electric 4m (
5) The speed (/r) is a smooth waveform with no overshoot.

The operation from time t5 to t6 is similar to that described in FIG. 5, and at this time the switch Sw is switched to A again.

That is, in the deceleration operation that is executed twice after the fixed position stop F start command is input (normal speed &"6S orientation speed Hcl and orientation speed H"1\crip speed trr2), after reaching the orientation speed. The integral term of the speed loop is reset during the period until switching to the position loop, and slip control is performed using only the proportional term. Therefore, by increasing the orientation speed, stable fixed position stop control can be performed, and arbitrary When a fixed position stop command is input to a motor rotating at high speed, GD2 on the machine side, which becomes the load of the motor,
Regardless of the size of the motor, the shaft of the motor can be stopped at the target stopping point with smooth operation without speed overshoot.

[Effects of the Invention] As explained above, the present invention is capable of executing a fixed position stop with smooth motion without overshoot when a fixed position stop command is input, so that the fixed position stop can be executed by increasing the orientation speed. This has the effect that the stopping time can be shortened and stable and highly efficient fixed position stopping control can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a fixed position stop control method according to an embodiment of the present invention, FIGS. 2(a) to (e) are waveform diagrams according to the fixed position stop control method shown in FIG. 1, and FIG. A speed loop block diagram is shown, (a) is a conventional example, (b) is an example of the present invention, FIG. 4 is a block diagram of a conventional fixed position stop control system, and FIGS. 5 (a) to (e) 4 is a waveform diagram based on the fixed position stop F control method shown in FIG. 4. FIG. In the figure, (4) is an inverter device, (5) is an induction motor, (7)
is a pulse transmitter, (8) is a speed command circuit, (9) is a speed detection circuit, (lO) is a pulse detection circuit, , (
11) is a slip frequency calculation unit, (IIA') is a PI calculation circuit, and CIIB) is a P calculation circuit. (15) is a voltage detection circuit. (18) is a pulse width modulation control circuit. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa Figure 2 Figure 3 (a) Figure 5 Procedural amendment (voluntary) 1. Indication of case Japanese Patent Application No. 139469/1982 2.
Name of the invention: Induction motor position control system stop control system 3, person making the amendment 5, detailed description of the invention in the specification to be amended. Contents of the 6° correction (1) The statement "80%" on page 2, line 20 of the specification is corrected to "90°". (2) The statement "512 shots" on page 3, line 2 of the specification is corrected to "r1024 shots." (3) The statements "overshoot reduction" on page 6, line 10 and page 7, line 6 of the specification are corrected to "overshoot phenomenon."that's all

Claims (1)

[Claims] Until the in-position signal indicating the position where the induction motor should stop is output based on the detection pulse indicating the rotational position of the induction motor driven by the inverter device, the speed reference and the estimated value of the induction motor are In a fixed position stop control method for an induction motor in which the inverter device is pulse width modulated controlled to perform deceleration operation of the induction motor based on the output slip value of a slip frequency calculator that calculates the slip based on the deviation, during the deceleration operation A fixed position stop control method for an induction motor, characterized in that the integral term of the speed loop is reset during the period from when orientation speed is reached until switching to the position loop, and slip control is performed using only the proportional term.