JPS6055877A - Overload protecting device of dc motor - Google Patents

Abstract

PURPOSE:To prevent a motor from burning out by interrupting the energization of the motor when a deviation between the speed command value and the actual rotating speed of the motor is the prescribed value or higher even if the prescribed time is elapsed. CONSTITUTION:An up-down counter UDCNT up or down counts the output of an encoder E coupled directly with the shaft of a motor M in response to the rotating direction signal of the motor M. A microcomputer MPU controls the rotating direction and the speed of the motor M in response to a speed command SC, a position command PC, an operation command CTL, and a counted value COUNT. Further, it calculates a deviation between the speed command and the rotating speed of the motor at every prescribed time, and judges that the motor is in an overload state if the deviation continues for the prescribed time or longer in the prescribed value or higher state, thereby stopping the energization of the motor.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates primarily to an overload protection device for a DC mode equipped with a detector, and in particular to prevent the mode rotation speed from reaching a certain speed command value due to overload. The present invention relates to an overload protection device for a DC mode that can reliably prevent burnout or the like due to non-detection when the detection is not possible.

[Background of the invention]

Conventionally, regarding the control of a DC mode, the rotation speed of the mode is detected from the change in the output pulse of a position detector (hereinafter referred to as an encoder) in the cabinet at a certain time in accordance with the speed command to the mode. It is known to control the mode rotation speed to match.

For example, speed and
Position control is performed by counting up or down the encoder pulses output as the modele rotates, depending on the direction of rotation, and detecting the rotational speed of the modele based on changes in the pulses over a certain period of time. Additionally, the number of pulses output from the encoder is used to detect and control the position movement.

This will be explained with reference to FIG. 1 in the case of a DC mode equipped with an encoder.

FIG. 1 is a block diagram of a DC mode control system.

That is, in the DC mode M, the transistor QA←3.
The four transistors QAH, Q++(g), and Qm(@) are connected to the center of the full bridge type, and the pace of each of these transistors is the resistance 几A(t) and 几A(→.

1LeO is connected to the microcomputer MPU via 11 (→).

Then, when the transistor Q^0→IQA (c) is turned on by the output of the microcomputer MPU, the DC moder M rotates forward and the transistor 11 (-1-).

When Qn (to) is turned on, the DC mode module MU is rotated in the opposite direction.

Further, an encoder E is directly connected to the axis of the DC modele M, and as the DC modele M rotates, the encoder E generates outputs φ and φB showing the respective waveform phase diagrams in FIG.
It outputs two-phase rectangular waves with different phases.

The outputs φA and φB have opposite phases, depending on the direction of rotation of the DC moder M. That is, when the DC moder M rotates in the forward direction, the output φ^ advances, while when the DC moder M rotates in the reverse direction, the phase of the output φB advances.

Thus, the up/down counter circuit UDCNT detects the rising and falling edges of the outputs φ^ and φB of the encoder E, as shown by pulse FC in FIG. The quadrupled pulse PC is counted up or down according to the rotation direction of the DC mode model M, and the counter value COUNT
is input to the microcomputer MPU as velocity or position information.

Further, the up/down counter circuit UDCNT converts the rotational direction signal of the DC mode M, that is, the rotational direction signal ROT in FIG. iL is input to the microcomputer I'vlPLT.

INF is an interface circuit, and this interface circuit INF and the above-mentioned microcomputer MPU are related to an instruction control section. In addition, l
B+ eye is 1) to the right of C modele M.

The current direction is on the left.

With such a configuration, the summer speed command SC5 position command PC and operation command CTL are transmitted via the interface circuit INF.
When inputted manually to the microcomputer MPU, the microcomputer MPU calculates the output signal fed back from the encoder E using the counter value processed by the up/down counter UDCNT and the speed commanded in the rotation direction. Move to the commanded position and stop.

However, if the load on the moder M is too heavy, as shown in Fig. 3, if the deviation of the actual moder rotational speed is f+lli or more with respect to the command method to the modele 1,
The actual mode rotation speed continues to differ by more than the deviation value. In this case, the microcomputer MPU turns on the drive transistor and tries to accelerate because the actual speed of the mode is low compared to the speed command, and eventually the state of applying full weight continues, causing the mode to heat up and the temperature to rise. Upper row limit 'f: If exceeded, a problem arises in that the moder coil is bent.

In other words, if the load on the moder is excessive, the rotational speed of the modele will not rise to the speed command value, and a deviation will continue to occur, and the full voltage will always be applied to the modele, resulting in the problem described above. .

[Purpose of the invention]

The present invention was made in view of the above circumstances, and it is possible to prevent mold burnout by detecting the abnormality and switching off the current to the mold when the mold continues to be overloaded. The purpose of the present invention is to provide a method for overload protection of a DC mode.

[Summary of the Invention] l) The C-mode overload protection device according to the present invention prevents a deviation of a certain amount or more between the speed command 1st shift and the actual mode 2 mode rotation speed even after a certain period of time has elapsed. If so, it is determined that the moder is in an overloaded state, and the connection to the modele is cut off as an abnormality.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 4.

In the DC mode overload protection device according to the present embodiment, the microcomputer MPU as the energization control device takes the continuous command SC w'C and further outputs the counter value C0UN'l.
Read L', counter value C0U at -1 constant time
It calculates the change in NT and outputs the model speed by '4. The microcomputer MPU is
In this way, due to the deviation between the speed command SC and the modele speed,
It performs speed 1 current control.

The speed control method used in this embodiment is based on changes in the output pulses of the encoder, and the rotation line of the moder is set to 9. Since the output is digitally controlled, the
Deviation f between the base speed command value and mode model speed 1ai:=
I try to count +. Therefore, the deviation that can be determined to be an overload of the moder is stored in the microcomputer MPU so that this deviation can be easily compared with the deviation between the modele speed command value and the modele actual speed.

Does a microcomputer calculate the total speed of 1 at regular intervals? Since, from this 05 period, the moder speed command value and
Condition 1 where the 11iil difference between the model speed and the speed is more than a certain value
It can be easily determined whether the process has continued for a certain period of time or not. If it continues for -2i hours or more, the moder is overloaded, so it is determined that there is an abnormality, all transistors are cut off, and power to the modele is stopped.

Usually, a determination time of one second is sufficient. If the difference between the speed command and the actual rotation speed of the moder remains above a certain value for several seconds during control, it is safe to assume that this is some kind of abnormality.

〔Effect of the invention〕

As described in detail in the above embodiments, the DC mode overload retaining device 6' according to the present invention calculates the actual rotational speed of the modele from the change in the output pulse of the position detector, and Since the power supply to the mold is stopped at certain times, an overloaded state of the mold can be quickly dealt with, and burnout can be reliably prevented, which is an excellent effect.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a DC mode control system showing a conventional example, Fig. 2 is a phase diagram of each waveform in Fig. 1, Fig. 3 is an explanatory diagram of speed for theoretically showing the present invention, Fig. 4
The figure is a flowchart showing one embodiment of the present invention. M...DC mode E...Encoder, MPU
...Microcomputer (Electrification tlill Shun 11↓
■１、C0UNT・・・笥 ２ Kasumi ROT 0 -Kuchidera Rulo

Claims (1)

[Claims] In a DC mode equipped with a 16-position detector and a control circuit that controls the rotation speed and position based on the position detection signal from the 1.delta. detector, the rotation speed command by the control circuit and the actual mode rotation are By detecting when the deviation from the number continues for a certain period of time below a certain value,
DC mode overload protection device whose function is to disconnect the rvcg.