JPS6048998B2 - speed command device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed command device, and is an improved starting means for a motor speed control device.

Conventionally, as a means of accelerating the electric crosspiece at a target acceleration and smoothly rotating the loaded machine, an acceleration regulator was used to vary the settings of the motor control device to match the target acceleration. . These acceleration regulators include those with constant acceleration and those with gentle acceleration only at startup and completion of acceleration (generally known as S-shaped acceleration regulators).
It is common that a However, conventional motor speed control devices, such as thyristor Leonard devices that control DC motors, have a current control loop in the minor loop, the speed control loop is outside of the current control loop, and the speed control amplifier has a speed and acceleration regulator. P which amplifies the output
- An I amplifier or a P, I--D amplifier (P is proportional, I is integral, D is differential) is used, and a system is implemented in which the output is added to the input of the current control loop.

For this reason, even if only the speed command is set for the desired acceleration, the speed control amplifier has an integral element as mentioned above, so even if the settings are varied smoothly, if the current does not reach the load torque at startup, the motor Since the motor does not start rotating, there is a delay in following the motor speed when starting.

Figure 1 is a characteristic diagram showing the relationship between the operations. Figure 1a is the characteristic of the acceleration setting A of the acceleration regulator, and Figure 1b is the characteristic of the motor current B.
, and FIG. 1c shows the characteristics of the motor speed C, respectively. In the figure, the horizontal axis is time, and at the time of timely start, the motor current B has characteristics as shown in FIG. As mentioned above, when starting, the motor will not rotate unless the current reaches the load torque, so there will be a delay in motor speed C as shown in Figure 1c, and the speed control amplifier will not follow the setting. Because it tries to work,
The acceleration becomes greater than the set value, and the time will eventually be accelerated to point 2 while following the setting. As described above, the conventional system not only causes a follow-up delay at the time of starting, but also has the disadvantage of causing a large mechanical shock because the motor rotates at an acceleration higher than a set value.

The present invention was conceived in view of the above-mentioned points,
Until the current that matches the load is reached and the motor begins to rotate, use a different setting to start flowing the current. Until then, the acceleration regulator command is set to zero, and only after the motor has rotated can the acceleration be adjusted. The goal is to operate the command of the motor and accelerate the electric motor by completely following the acceleration regulator.

The present invention will be explained below based on the drawings of the embodiments.

FIG. 2 is a wiring diagram showing an embodiment of the present invention, and FIG. 3 is a characteristic diagram for explaining the operation of the present invention. In FIG. 2, 1 is a speed setting device, and 2 is a contact or non-contact switch. 3 is an acceleration regulator, the output characteristics of which are shown in acceleration setting A'' in FIG. 3a.

The acceleration regulator 3 receives the setting signal output from the speed setting device 1 when the switch 2 is turned on. When the setting signal output is input at time T2, the output of the acceleration regulator 3 increases at a constant acceleration, and is finally proportional to the input (time T2
). Reference numeral 4 indicates a minute setting device for adding a minute compensation signal, 5 indicates a contact or non-contact operation switch that is turned on during operation, and 6 indicates a calculation point.

7 is an electric motor, 8 is a control device for the electric motor 7, and 9 is a speed detector.

Reference numeral 10 denotes a rotation detector for detecting rotation of the electric motor 7, and when the electric motor 7 starts rotating, the switch 2 is activated.

When the operation switch 5 is turned on now, a speed command is applied by the minute setting device 4, and the motor current B increases as shown in Fig. 3b.
” begins to play (time T.

). As described above, the control device 2 and 8 have an integral element, so even a small amount of human power can operate the integral element to control the motor current B.
3' starts to gradually increase as shown in FIG. 3b, and when the current reaches a value corresponding to the load torque (time 11), the motor 7 starts rotating as shown in FIG. 3c. When the rotation detector 10 detects that the electric motor 7 has started to rotate and the switch 2 is turned on, the signal from the speed setting device 1 is output to the acceleration regulator 3 to set a constant acceleration as shown in the acceleration setting A'' shown in FIG. 3a. The motor speed C'' is added as a command to the calculation point 6, and the motor speed C'' increases smoothly as shown in FIG. 3c in accordance with the constant acceleration command.

In this way, until the motor current reaches a current corresponding to the load torque and the motor 7 starts rotating, the motor current is made to flow according to the speed command of the minute setting device 4, and until then, the command of the acceleration regulator 3 is It is set to zero and waits for the electric motor 7 to rotate before operating the command for the acceleration regulator 3.

Since the present invention has the above-described configuration, it is possible to follow the command without causing the motor speed to suddenly accelerate only at the time of starting due to a delay in follow-up compared to the conventional example. Note that the setting value of the minute setting device 4 is set to a level that does not impair the acceleration characteristics. Further, in the embodiment of the present invention,
Although we have shown and explained an example in which a rotation detector is provided, it goes without saying that in other embodiments where the load is stable, equivalent performance can be obtained even if the device is replaced with one that detects and holds the load current. .

As described above, according to the present invention, the electric motor can be rotated smoothly and the shock on the machine side can be reduced, making a great contribution to industry.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram for explaining a conventional speed command device.
FIG. 2 is a wiring diagram showing one embodiment of the present invention, and FIG. 3 is a characteristic diagram for explaining the operation of the present invention. 1...Speed setting device, 2...Switch, 3
...Acceleration adjuster, 4...Minute setting device,
5... Operation switch, 6... Calculation point,
7...Electric motor, 8...Control device, 9.
... Speed detector, 10... Rotation detector.

Claims (1)

[Claims] 1. A speed control device for an electric motor, which includes a speed setter that sets the speed, a rotation detector that detects that the electric motor has started to rotate, a switch that operates according to a detection signal from the rotation detector, and the speed setter. Equipped with an acceleration regulator that issues an acceleration command based on a signal, and a minute setting device that adds a minute compensation signal, the motor current reaches a current commensurate with the load torque.
The speed command of the minute setting device is applied until the electric motor starts rotating, and when it is detected that the electric motor starts rotating, the output is added to the output of the acceleration regulator to obtain the speed command. A speed command device characterized by: