Electricity: motive power systems – Positional servo systems – Plural servomotors
Patent
1986-10-16
1989-06-06
Ro, Bentsu
Electricity: motive power systems
Positional servo systems
Plural servomotors
318 51, G05B 1132
Patent
active
048374911
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Background of the Invention
This invention relates to a motor velocity control apparatus and, more particularly, to a motor velocity control apparatus used in a changeover control circuit of a spindle motor in a machine tool.
In machine tools, such as machining centers, a plurality of motors are employed. These motors ordinarily have different characteristics so that they can operate as high-output and low-output motors or as high-velocity and low-velocity motors, etc. However, since these motors perform differently on account of their output and velocity characteristics, each motor requires an exclusive servoamplifier for control. Moreover, in a case where one of the motors is used, there are many instances in which the other motors are at rest, so that control circuits of the servoamplifiers belonging to these motors also are at rest. Therefore, the cost of the equipment is high and the equipment is not utilized efficiently.
SUMMARY OF THE INVENTION
An object of the present invention is to lower the cost and raise the efficiency by utilization of a motor velocity control apparatus wherein the hardware for one servoamplifier is shared by each of the motors in an arrangement where a spindle, or the like, of a machine tool is driven and controlled by a plurality of motors which perform differently.
According to the present invention, there is provided a motor velocity control apparatus having a servoamplifier capable of controlling plural types of motors having different characteristics, the motor velocity control apparatus being characterized in that at least one of the following is included in the servoamplifier: storage circuit.
In accordance with the motor velocity control apparatus of the present invention, a single servoamplifier is adjusted so as to conform to the characteristic of each motor is changed over and connected when controlling a plurality of motors which differ in terms of characteristics and performance. The invention therefore has the following advantages: (e.g. 10 V); and large and small output.
In addition, since the apparatus can be constructed by arranging the amplifier on a single circuit chip, mass productivity can be enhanced and cost reduced. It is also easy to replace the amplifier should the amplifier malfunction.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating an embodiment of the present invention;
FIG. 2 is a flowchart illustrating an operation sequence of the present invention;
FIG. 3 is a schematic diagram of a changeover signal generating circuit;
FIG. 4 is a schematic diagram of a current feedback gain changeover circuit; and
FIG. 5 is a schematic diagram of a velocity feedback gain changeover circuit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention will now be described in detail with reference to the drawings.
FIG. 1 is a block diagram illustrating an embodiment of a motor velocity control apparatus acccording to the present invention.
In the FIGURE, spindle drive motors M.sub.1, M.sub.2 are for a machine tool, or the like. It is assumed that a first motor is characterized by a higher output or higher rotational velocity in comparison with a second motor, which is characterized by a different output or velocity. These motors are driven by a converting circuit (e) including a transistor inverter, or the like, controlled by an output signal from a PWM circuit (c). The supply of power to the converting circuit (e) is performed by a rectifying circuit (d) connected to a three-phase AC power supply R, S, T.
The rotational velocities of the motors M.sub.1, M.sub.2 are sensed by pulse generators PG.sub.1, PG.sub.2, which apply signals indicative of the sensed velocities to a velocity feedback gain changeover circuit (f). Also provided are a velocity loop gain changeover circuit (a) and a ROM changeover circuit (b) having a changeover circuit of a current loop amplitude and phase table storage circuit. The ROM changeover circuit (b) is provided with a plurality of memories. For example,
REFERENCES:
patent: 4257103 (1981-03-01), Suzuki et al.
patent: 4297624 (1981-10-01), Komiya
patent: 4464615 (1984-08-01), Rodi
patent: 4641069 (1987-02-01), Fujioka et al.
patent: 4644232 (1987-02-01), Nojiri et al.
Fujioka Yoshiki
Hirota Mitsuhiko
Fanuc Ltd.
Ro Bentsu
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