JPH0456560B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a variable speed motor equipped with an electromagnetic clutch and an electromagnetic brake, and particularly to a device for detecting and protecting abnormal conditions of the motor such as load restraint. .

[Conventional technology]

A conventional device of this type is shown in FIG. The figure shows a feedback control circuit for a motor (not shown), which is equipped with an electromagnetic clutch 7 and an electromagnetic brake 8. 1 is a rotation speed detection circuit that detects the rotation speed on the output side of the motor, 2 is a command circuit that specifies the rotation speed on the output side of the motor, and 3 is an electromagnetic clutch that compares the commands from the rotation speed detector 1 and the command circuit 2. 7 and a control logic circuit for calculating and outputting the conduction time of the electromagnetic brake 8; and 4, when the conduction time of the electromagnetic clutch 7 or the electromagnetic brake 8 becomes abnormally long, the output is cut off to prevent burnout of the motor. 5 is a transistor for driving the electromagnetic clutch 7, and 6 is a transistor for driving the electromagnetic brake 8.

Next, the operation will be explained. The control logic circuit 3 compares the speed signal from the rotation speed detector 1 on the output side of the motor with the command signal from the command circuit 2, and if the speed signal is large, it drives the electromagnetic brake 8, and if the speed signal is small, it drives the electromagnetic clutch 7. If the speed signal and the command signal match, the electromagnetic clutch 7 and the electromagnetic brake 8 are configured so that neither is driven, and the rotation speed on the output side of the motor is set to the rotation determined by the command circuit 2. It is controlled so that it becomes a number. Therefore, during normal operation, the electromagnetic clutch 7 is ON/
The vehicle is operated in the OFF state, and the electromagnetic brake 8 is driven when reducing the speed or stopping the vehicle. The protection circuit 4 detects that the conduction time of the electromagnetic clutch 7 becomes abnormally longer than usual when the load on the motor becomes abnormally large, and stops driving the electromagnetic clutch 7. Further, even if a command signal is output from the command circuit 2, the drive of the electromagnetic clutch 7 is stopped even if the speed signal from the rotation speed detector 1 is not generated for a certain period of time or more. There is.

[Problems with conventional technology]

In the conventional protection circuit described above, it is essential to provide a protection circuit separate from the logic circuit for performing feedback control, and the disadvantage is that the circuit configuration of the protection circuit becomes complicated. Furthermore, even when the motor is restrained, the motor output shaft often makes small reciprocating movements, and the speed signal from the rotational speed detector does not reach zero, resulting in a serious drawback in that the protection circuit does not operate properly.

〔the purpose〕

This invention was made to eliminate the above-mentioned drawbacks of the conventional ones, and its purpose is to provide a device in which speed control is performed using a microcomputer, and at the same time, a protection circuit is also operated. .

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, numerals 1, 2, 5 to 8 indicate the same or equivalent parts as shown in FIG. 21 is a microcomputer that controls the motor speed and protects the motor; 22 is an interrupt circuit that provides a timing signal to the microcomputer 21 to control the speed and protect the motor; when the microcomputer 21 receives the timing signal from the interrupt circuit 22; It is configured to temporarily suspend other operations and give priority to speed control and protection operations.

FIG. 3 is a flowchart for explaining the operation of the embodiment shown in FIG.

Next, the operation will be explained. The interrupt circuit 22 generates an interrupt signal at regular intervals.
As soon as this interrupt signal is read by the microcomputer 21, the microcomputer starts interrupt processing, that is, motor speed control and protection operation.

First, speed control will be explained. When the interrupt signal is read, the microcomputer 21 executes the operations shown in the flowchart of FIG. That is, the central processing unit C compares the speed signal VNOW from the rotation speed detector 1 and the command signal VSET from the command circuit 2, and if VNOW-VSET<0, turns on the electromagnetic clutch CL7, and VNOW-VSET=0. If so, use electromagnetic clutch CL7 and electromagnetic brake BK8.
OFF, and if VNOW-VSET>0, the electromagnetic brake BK8 is turned ON. The operations described above are executed every time an interrupt signal is generated, and the controlled motor (not shown) is controlled to rotate at a constant speed. Also, the command signal
It is clear that if VSET changes, the speed will be controlled according to this signal. Next, the operation of the protection circuit will be explained. In the flowchart (Figure 3) of the motor speed control operation explained above, an auxiliary memory has a sequence memory section, a numerical value setting memory section, and a count value memory section for motor protection operation.
PROT is shown. This auxiliary memory PROT is associated with the number of interrupt operations performed at fixed time intervals. Initially PROT is cleared to 0
It's getting old. Next, when an interrupt signal is input and the microcomputer 21 executes the flowchart of FIG. 3, the auxiliary memory PROT receives the interrupt signal only when the electromagnetic clutch 7 and the electromagnetic brake 8 are ON. Count the number of times. Also, when the electromagnetic clutch 7 and electromagnetic brake 8 are turned off at the same time, the auxiliary memory
PROT is configured to be cleared to 0. Furthermore, if the above counting result is less than the numerical constant M, the normal speed control described above is performed, and if the counting result exceeds M, the electromagnetic clutch 7 and the electromagnetic brake 8 are turned off, and an alarm circuit is activated to protect the motor. It is designed to do this.

〔effect〕

As described above, according to the present invention, the speed of the motor is controlled by the interrupt operation of the microcomputer, and the overload protection of the motor is also performed in conjunction with this interrupt operation.
The electromagnetic clutch can be protected, there is no need to provide a separate protection circuit, and the reliability of the protection is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control device including a conventional motor protection circuit, FIG. 2 is a block diagram showing a control device including a motor protection circuit according to an embodiment of the present invention, and FIG. 3 is a block diagram showing a control device including a motor protection circuit according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating the operation of FIG. In the figure, 1 is a rotation speed detection circuit that detects the rotation speed of the motor, 2 is a command circuit that commands the rotation speed, 7 is an electromagnetic clutch, 8 is an electromagnetic brake, 21 is a microcomputer, 2
2 is an interrupt circuit, and PROT is an auxiliary memory.

Claims (1)

[Claims] 1. A variable speed motor equipped with an electromagnetic clutch 7 and an electromagnetic brake 8, a rotation speed detection means 1 for detecting the speed on the output side of the variable speed motor, and a command speed on the output side of the variable speed motor. When the interrupt signal is received, the command means 2 compares and calculates the signal from the rotation speed detection means 1 and the signal from the command means 2, and turns on and off the electromagnetic clutch 7 and the electromagnetic brake 8 according to the result of this calculation. A microcomputer 21 is provided which controls the speed of the variable speed motor by performing off control, and an interrupt signal is input to the microcomputer 21 only when the electromagnetic clutch 7 is in the on state and the electromagnetic brake 8 is in the on state. A counting section that adds up and counts the number of times the number of times has passed, a memory that presets numerical constants, and compares the setting value of this memory with the addition count value of the counting section, and when the value of this counting section exceeds the value set by the memory, It incorporates a processing section that issues a command signal to turn off both the clutch 7 and the electromagnetic brake 8, and resets the count value counted by the counter to 0 when both the electromagnetic clutch 7 and the electromagnetic brake 8 are in the off state. A protection device for a variable speed motor, characterized by: