JPS60125186A - Controller of motor - Google Patents

Abstract

PURPOSE:To smoothly accelerate or decelerate a motor by limiting or setting to zero a current of the motor by a driven operation command and varying the speed of the motor in accordance with a speed reference signal. CONSTITUTION:A switch 15-1 inputs the speed set signal Vr of a speed setter 1 to an acceleration limiter 2 at the normal operation time, and a switch 15-2 inputs the voltage signals V1, V2 set by current limit setters 17, 18 to a current limiter 14-2. When switched to a driven operation, the switches 15-1, 15-2 are switched. Thus, an input signal of the limiter 2 is switched through a polarity inverting amplifier 16 to a speed feedback signal -Vsf, and current limit set voltage V1, V2 inputted to the limiter 14-2 are simultaneously switched to zero. Thus, even if switched to the normal operation from the madway of the driven operation, smooth acceleration or deceleration can be performed.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a control system for an electric motor, and in particular to a control device for an electric motor that enables coasting operation of a crane or the like when speed control is performed. Regarding.

[Technical background of the invention and its problems] A speed control device using a thyristor Leonardo using a DC motor is used as a traversing and traveling control system for general overhead cranes, steel manufacturing cranes, etc. In addition, recently, speed control using an inverter method using an induction motor 4#
et has come into widespread use.

As an example of a conventional speed control device, a thyristor Leonard system using a DC motor is shown in FIG.

This speed control system is configured with a minor (-) current control system. In other words, it is converted into speed setting circuit 1 or quasi-signal ■3. When the speed reference signal Vr is returned to zero in a stepwise manner Similarly, the converted speed reference signal Vs is compared with the feedback signal Vsf from the speed detector 11, and the speed deviation signal Ve is amplified by the speed control amplifier circuit 3, and its output signal is Vc becomes a current reference signal.

A current Id of the motor 9 is supplied from a current power source 12 via a thyristor device (power conversion device) 6, and a current feedback signal Vcf proportional to the current Id is detected via a current transformer 7 and a current detection circuit 8. . The current reference signal Vc is compared with the current feedback signal Vcf, and the current control amplifier circuit 4 is driven by the current deviation, and the phase control circuit 5 and the thyristor device 6 are controlled to control the current so that the current deviation is reduced.

When the conventional electric motor control device as described above is used to control the speed of a crane or the like, the following problems arise.

That is, the traversing and traveling of the crane includes an operation based on coasting called coasting operation (hereinafter referred to as coasting operation). If the crane is operated by coasting, when the load swings forward in the operating direction, the crane will also coast and be pulled forward, and if the stop operation is performed when the crane and the load are perpendicular, the load will not swing as much and the operation will be easier. It becomes easier. When moving a load, when the target position is approached, coasting is performed several times and the stop operation is performed as described above. However, in the conventional configuration, coasting operation is not possible because the deceleration occurs due to the rate β of the acceleration limit times M2, as shown by the broken line A (2) in Figure 3. Although coasting operation is possible, when the control is used to return to acceleration operation from the middle of coasting operation, the speed reference signal Vs is set to acceleration limit circuit 2.
is output from zero at a predetermined rate α. Therefore, immediately after the return operation, there is a considerable speed deviation between the speed reference signal Vs and the feedback signal Vsf (the value is approximately V
sf ), and the actual speed is once decelerated from the speed of the smiling leg B in FIG. 3 as indicated by the broken line C. and speed reference signal Vs
From the point in time when the feedback signal Vsf and the feedback signal Vsf become equal to each other, the acceleration is accelerated according to the rate α of the acceleration limiting circuit 2 as indicated by #D.

Such a speed change causes the actual speed to temporarily decelerate, contrary to the operator's will to increase the speed, and the deceleration at that time is the maximum deceleration torque the device has. Therefore, there is a problem in that S-strokes are applied to machines, etc.

[Object of the Invention] The present invention was made to solve the above-mentioned problems, and its purpose is to control an electric motor that makes use of speed control and enables coasting conduction without giving a shock to a machine, etc. The goal is to provide equipment.

[Summary of the Invention] In order to achieve the above object, the present invention provides a second speed reference signal that changes to the set value at a predetermined rate of change when the first speed reference signal is input and its setting 1- changes. In the device, the device includes an acceleration limiting circuit that outputs an acceleration limit circuit and controls the speed of the electric motor to a speed according to the second speed reference signal, in which the current of the electric motor is set to #JU# or zero by a creeping operation command, and the A cold operation control circuit is installed to control the second speed reference signal so that it follows the speed of the motor and changes from cold operation to normal speed control operation (so that smooth acceleration and deceleration can be achieved even when secondary speed is changed). This is a control device for an electric motor.

[Embodiment of the Invention] An electric motor control device according to the present invention will be explained based on an embodiment shown in FIG. 1. In FIG. 4, the same reference numerals as in FIG. 1 represent the same elements, so the explanation will be omitted and only the different parts will be explained. 14 is a speed control amplifier which has a new function according to the present invention, 15-1 is a switch that is switched during cold operation, and 16 is a polarity inversion amplifier. FIG. 5 is a circuit diagram showing an example of the speed control amplifier 14 in detail. In Fig. 5, 14-1 is a speed control operational amplifier;
Reference numeral 2 denotes a current limiting circuit, which is composed of an operational amplifier 14-3, 14-4 and a diode 14-5, 14-6. 15-
2 is a switch which is switched during cold operation and operates in conjunction with switch 15-1; 17 and 18 are current limit setters for limiting the flow reference number VcO value.

In the above (d configuration) 1 During normal operation, switch 15-
1.15-2 is left in the state shown. That is, the switch 5-1 inputs the speed setting 4m Vr of the speed setting circuit 1 to the acceleration limiting circuit 2, and the switch 15-2 inputs the pressure signal 1 set by the current limit setting device 17.18.

vB is inputted to the current limiting circuit 14-2. Therefore, 1
The current Id of the motor 9 is allowed to flow up to the current set by the current limit setting a17.18, and normal speed control operation can be performed at the set speed of the speed setting circuit 1.

When the vehicle is operated at a constant speed and the vehicle is switched to cruising mode, the switch 15-1.1b-2 is switched to the opposite side as shown in the figure. As a result, the input signal I''i of the acceleration limiting circuit 2 is switched to the speed feedback signal -Vsf via the polarity inverting amplifier 16, and at the same time, the current limit setting voltage ■l+V2 input to the current limiting circuit 14-2 becomes zero. Therefore, the current reference A No. Vc becomes zero and the electric motor 9
The current Id is controlled in a controlled manner, resulting in continuous operation using only inertial energy. However, since the speed change due to the driving is slower than the acceleration/deceleration rate of the acceleration/deceleration limiting circuit 2, the speed reference signal Vsld, which is the output of the acceleration/deceleration limiting circuit 2, changes by following the speed feedback (t3 - Vsf). Even when switching to normal operation in the middle of driving, smooth acceleration/deceleration operation can be performed from the current speed.Third.
The solid line E shown in the figure is a diagram showing an example when the vehicle is accelerated after returning to normal driving from the middle of cruising driving.

Effects of the Invention As explained above, according to the present invention, when a crane or the like is operated such as traversing or traveling using a speed control device,
Enables coasting operation and returns from coasting to normal speed JK
It is possible to obtain a rational electric motor control device that accelerates and decelerates at a predetermined rate according to the operator's will even when returning to mi-controlled operation and does not cause shock to machines and electrical equipment.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a conventional control device by Siris Leonard for a DC motor, Fig. 2 is a time chart explaining the operation of the acceleration limiting circuit 2, and Fig. 3 is a detailed explanation of the conventional control device and the present invention. The operating characteristic diagram, Fig. 4 is a configuration diagram showing an embodiment of the present invention, and Fig. 5 1 is the speed of Fig. 4! DIj
2 is a detailed circuit diagram of the ml amplifier 14. FIG. 1... Speed setting circuit 2... Acceleration limiting circuit 3... Speed j! ili control i\V-circuit 4... stealth current control amplifier circuit 5... phase control circuit 6... thyristor device 7.
・'Rkt device 8... Electric υIL detection circuit 9... Motor IO... Field 11... Speed detector 12... AC power supply 13... Field power supply 14... Speed control amplifier 1
4-1.3.4...Operation amplifier. ]4-2... Current limiter circuit 14-5.6... Diode 15-1.2... Switch L6... Polarity inversion amplifier 17.18... Current limit setting device agent Patent attorney Kensuke Chika (1 person) Figure 1 Figure 2 Figure 3 Figure 4/2 Figure 5

Claims (1)

[Claims] an acceleration limiting circuit that outputs a second speed reference signal that changes to the set value at a constant change rate b1 when the first speed reference signal is input and the set value thereof changes; In a device that controls the speed of an electric motor to a speed according to the speed of the electric motor, the current of the motor is limited or zeroed by a time-striking operation command, and the second speed reference signal is changed to follow the speed of the electric motor. What is claimed is: 1. A control device for an electric motor, characterized in that it is provided with a driving operation control circuit that controls the operation so as to perform the following operation.