JPS6369475A - Motor controller - Google Patents

Abstract

PURPOSE:To suppress rush current to be low, by interrupting the output of a current detection circuit within the lagging time of the current detection circuit, and by controlling the gradual increment of rotational frequency control voltage. CONSTITUTION:By a one-shot multi-vibrator g interlocked with the operation command signal of a motor 6 and with a trigger, a current detection voltage keying circuit 11 is released just for a time T corresponding to the lagging time of a current detection circuit 4, and for the time, a current control circuit 2 is contrived to be controlled just by the output voltage of a rotational frequency control voltage gradual-increment circuit 10. A switch 7 is interlocked with motor operation command signal to he connected to, and so the output voltage of the rotational frequency control voltage gradual-increment circuit 10 is always started from the minimum rotating state on, and rush current flowing to the motor 6 is suppressed to be the lowest. After the time T, the current detection voltage keying circuit 11 is closed, and so the driving current of the motor 6 is controlled to be constant.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motor JII control device that automatically controls drive current.

2. Description of the Related Art In general, in order to obtain stable rotational operation of a motor despite load fluctuations, it is necessary to perform speed control to control the rotational speed of the motor and current control to control the drive current. Figure 2 is a configuration diagram of a conventional motor control device that performs current control.
is a current control circuit, which has a rotation speed control voltage 1 and a current detection circuit 4.
The control system operates so that the motor drive current flowing to the current detection circuit 4 becomes constant by comparing the output voltages of the power control circuit 3 and the control 1 to the current detection circuit 4. Therefore, even when the load on the motor 6 changes, the motor drive current remains constant, and the motor 6 operates stably with a constant output.

However, in the conventional configuration, the current detection circuit 4 does not follow the inrush current at the time of starting the motor due to the delay time required for control, and therefore the control system Since the power control circuit 3 starts shifting from a state where the drive current is zero and supplies the maximum power, there is a period when an even larger inrush current flows.

In order to solve the above problems, the present invention reduces inrush current by controlling the output voltage of the current detection circuit in conjunction with the motor operation command signal. The purpose is to provide all motor and tilj control devices with a soft start circuit.

Means for Solving Interval Points In order to achieve the above object, the motor control bag fiR of the present invention
compares the current detection circuit that detects the motor drive current, the output voltage of the current detection circuit, and the motor rotation speed control voltage,
a current control circuit that controls the power control circuit to keep the drive current of the motor constant; a current detection circuit that is controlled by the output of the current control circuit Yj and controls the power supplied to the motor; This configuration includes a soft start circuit that opens and closes the output of the current detection circuit and gradually increases the rotation speed control voltage in conjunction with a motor operation command signal.

Function The present invention has the configurations 1 to 1 above, so that the delay f1 of the current detection circuit is
During this time, the output of the current detection circuit is cut off to open the control loop, and at the same time, the rotational speed control voltage is gradually increased (511 is controlled) to start the motor from a low rotational speed, making it possible to prevent excessive inrush current.

Embodiment FIG. 1 is a configuration diagram showing an embodiment of the present invention. Components having the same functions as those in the configuration diagram of a conventional motor control device in FIG. do. Reference numeral 12 indicates the entire soft start circuit, which will be explained below along with its constituent elements. , A, 8 is a switch that is linked to the motor operation command signal, switch 7 opens and closes the rotation speed control voltage 1 input to the rotation speed control voltage gradual increase circuit 10, and the switch 7 is connected. Trigger the one-shot multivibrator 9. The one-shot multivibrator 9 triggered in conjunction with the operation command signal of the motor 6 generates an output signal for a time T corresponding to the delay time of the current detection circuit 4. During this period, the current control circuit 2 is brought into a state in which avT can be controlled only by the output voltage of the rotation speed control voltage gradual increase circuit 10. Switch 7 (ri, connected to ground potential when the motor is stopped,
Since it is connected to the rotation speed control 7E pressure 1 in conjunction with the motor operation command signal, the output voltage of the rotation speed control voltage gradual increase circuit 10 always starts from the lowest rotation state, and the rush current flowing to the motor 6 is kept to a minimum. . Since the current detection voltage switching circuit 11 is closed after time T, an automatic control loop for current control is formed, and control is performed to keep the drive current of the motor 6 constant.

As is clear from the embodiment described in "The Childhood of the Invention", the present invention allows the output of the current detection circuit to be set to 1 during the delay time of the current detection circuit to open the control loop, and at the same time gradually increases the rotation speed control voltage. death,
Since the motor is configured to start at low rotation speeds, it is possible to suppress the inrush current when starting the motor, and the power supply and power control circuit ratings can be designed to be small, reducing costs and eliminating excessive It is possible to realize a current control motor control device that has excellent effects in that circuits and motor failures caused by inrush currents are reduced and reliability is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a morph control device showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional motor control device. 1... Rotation speed control voltage, 2... Current control circuit, 3
...Power control circuit, 4...Current detection circuit, 1
2...7 Start [J3゜Name of agent: Patent attorney Toshio Nakao and 1 other person7-
Rotation control voltage 2 - Current control circuit 3 - 77% recirculation Circuit 4 - Current control circuit 5 - 9i circuit 6 - Motor IZ - Soft start circuit Fig. 1 Fig. 2

Claims (1)

[Claims] A current detection circuit that detects the motor drive current is compared with the output voltage of the current detection circuit and a rotation speed control voltage that determines the motor rotation speed, and the power control circuit is controlled to keep the motor drive current constant. a current control circuit that controls the output of the current control circuit; a power control circuit that is controlled by the output of the current control circuit and controls the power supplied to the motor; and a power control circuit that opens and closes the output of the current detection circuit in conjunction with a motor operation command signal. A motor control device characterized in that it is equipped with a soft start circuit that performs gradual increase control of a rotation speed control voltage.