JPS6315697A - Controlling method for ac spindle motor - Google Patents

Abstract

PURPOSE:To control a motor according to a loaded condition with a simple measure by providing a control circuit with an interface and changing according to a load a maximum torque and other characteristics of the motor directly by a command from an external command circuit. CONSTITUTION:An exciting current command circuit is provided with an interface X and a CPU Y and said CPU Y is connected with a memory ROM storing various kinds of information. Also, said interface is provided with a code signal inputting part to input a signal from an external command circuit A to the CPU Y via the interface to change according to a load motor characteristics, for example, a limiting value of torque limit as shown in the drawing. Moreover, a current vector arithmetic circuit h is also controlled directly by the CPU Y.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an AC spindle motor control method configured so that an external command circuit can directly issue commands to change the characteristics of the motor.

(Prior Art) With recent advances in computer control technology, control methods have been put into practical use that operate various electric motors with predetermined characteristics using command signals from a CPU (Central Processing Unit).
Figure 6 shows an example of a control circuit that performs such control. In Figure 0, which shows an example of vector control of an AC spindle motor (M), circuit, B is the numerical system 1f (NC) section, C is the excitation current command circuit, D is the spindle motor control circuit, E
is an AC power supply, and G is a pulse generator.

The excitation current command circuit C includes a comparator a that obtains a deviation signal from a speed command signal from the NC control section and a speed signal from the pulse generator G, a speed control amplifier b that amplifies the deviation signal, and a clamp for the maximum value of torque. a function generator C1 for automatic field weakening circuit d, a magnetic flux control amplifier e, a divider f for calculating torque component current iq by dividing the torque command T obtained by the function generator by the magnetic flux obtained by the magnetic flux control amplifier. , magnetizing current td
, and a current vector calculation circuit that calculates each phase command current io of the AC motor F from the torque component current iq and the magnetization current id.

In addition, the spindle motor control circuit has each phase command current io,
It is composed of a current control amplifier i, a pulse width modulator (PWM) j, and an inverter k, which calculate an deviation current ie based on a signal ir from a current transformer (CT) that detects the actual current of an AC motor F.

(Problems to be Solved by the Invention) In the AC motor control circuit as described above, the motor characteristics are defined by the automatic field weakening circuit for magnetic flux and the function generator for torque. The torque limiter, which limits the maximum value of the upper and lower limits of torque, is provided to limit the acceleration/deceleration torque and to ensure normal operation by preventing the slip frequency detection circuit (not shown) from exceeding its operating limits. There is. However, the motor is not always operated at the rated load, and even if you try to change the motor characteristics such as maximum torque or maximum rotation speed according to the light or weight of the load, the CPU will perform complex calculations and then issue commands. Therefore, there is a problem in that the processing capacity of the CPU is required to be extra, and the operation for rotating the motor in the M direction with the optimum characteristics suited to the load becomes complicated.

Therefore, the present invention aims to solve the problems of the prior art, and provides an AC spindle motor control method in which a command signal for changing motor characteristics is output directly from an external command circuit to an interface of a motor control circuit. It provides:

(Means for Solving the Problems) The AC spindle motor control method of the present invention is configured as follows. That is, in a device that controls an AC spindle motor by providing an arithmetic control unit having a central processing unit that is driven by a signal from an external command circuit and sends a control signal to an AC spindle motor control circuit, the interface of the control circuit includes: The AC spindle motor is characterized in that the AC spindle motor is controlled by directly inputting a signal that limits the characteristics of the motor from an external command circuit.

(Function) The present invention sends a control signal to the control circuit of an AC spindle motor by an arithmetic control unit having a CPU driven by an external command circuit. Since the AC spindle motor is controlled by applying a signal that limits the characteristics of the motor to the interface, the motor can be controlled according to the load condition through simple processing.

(Example) In the AC motor control circuit shown in Figure 0, an example of the present invention will be described below with reference to figures.In the present invention, an excitation current command circuit is provided with an interface It is configured to be connected to the stored memory ROM. Then, the interface is provided with a code signal input section of, for example, 8 bits or more, and the signal from the external command circuit A is input to the CPUY via the interface, and the motor characteristics, in the example shown in the figure, the limit value of the torque limit, are set as the load. This allows for changes to be made depending on the situation. Furthermore, the current vector calculation circuit is also configured to be directly controllable by the CPUY. In this case, the command signal from the external command circuit A may be a parallel input or a serial input, and the command signal from the external command circuit may be not only a program using a tape but also a setting of motor characteristics using a keyboard.

Note that the motor characteristic limitation command from the external command circuit may be maximum torque, maximum output, maximum rotation speed, etc. Furthermore, the AC motor control circuit is not limited to the configuration shown in the figure, and may be any of the following: It can be applied to other configurations as long as it is controlled by the CPU by providing an interface to the CPU.

(Effects of the Invention) As explained above, according to the present invention, when an AC spindle motor is controlled by a CPU, an interface is provided in the control circuit of the motor, and the maximum torque of the motor is directly controlled by a command from an external command circuit. Since these characteristics can be changed according to the load, the AC spindle motor can be controlled in an optimal state, and the spindle connected to the output shaft of the motor can be effectively adjusted.

[Brief explanation of drawings]

The figure shows a control circuit for an AC spindle motor.
External command circuit, B...NC control unit, C...excitation current command circuit, D...spindle motor control circuit, E...AC power supply, F...AC spindle motor, G...pulse Generator.

Claims (1)

[Claims] An AC spindle motor is controlled by providing an arithmetic control unit having a central processing unit, which is driven by a signal from an external command circuit and sends a control signal to an AC spindle motor control circuit, and an interface of the control circuit,
An AC spindle motor control method characterized by driving the AC spindle motor by directly inputting a signal that limits the characteristics of the motor from an external command circuit.