JPH0116115B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] This invention relates to a speed control method for controlling the line speed of multiple electric motors that are mechanically coupled or uncoupled depending on materials etc. to be constant in the general industrial field. It is related to.

[Prior art and its problems]

Conventionally, a large number of transfer means with drive rolls and idle rolls arranged facing each other are installed with a predetermined distance between them.
2. Description of the Related Art A device is known that transfers a material in a fixed direction while sandwiching the material between the driving roll and an idle roll.

In this type of transfer device, when material of a predetermined size is intermittently fed and transferred, the line speed of the electric motor that drives each drive roll becomes unstable due to load fluctuations, so the line speed must always be kept constant. Therefore, various speed control methods have been proposed to stably control the speed of multiple electric motors.

For example, as a conventional speed control method for multiple electric motors, one having a circuit configuration shown in FIG. 1 is known. That is, FIG. 1 shows a drive roll 12 and an idle roll 14 driven by an electric motor 10.
This shows the case where two transport means equipped with
A speed regulator 16 and a torque regulator 18 are connected to each electric motor M ₁ and M ₂ to adjust the speed based on a speed setting signal. In addition, each electric motor
A speed detector 20 is provided for each of M ₁ and M ₂ , and the speed detector 20 is connected to feed back the detected value to the speed regulator 16 . Further, a material detector 24 for detecting the material 22 is provided adjacent to each of the drive rolls 12, and signals obtained by detecting the material by these detectors 24 are supplied to a material tracking circuit 26,
It is configured to determine whether the material 22 is caught in both drive rolls 12, 12. Therefore, when the material tracking circuit 26 determines the tracking state of the material described above, the electric motor (M ₂ in this case) other than the electric motor (M ₁ in this case) serving as the speed reference
The configuration is such that an ON signal is output to a switch circuit 30 of a droop characteristic circuit 28 provided for a speed regulator 16 to give a droop characteristic to the motor speed. Therefore, with the conventional speed control method, the line speed can be controlled to be constant and the load balance can be stably maintained by the above-described configuration.

However, according to the conventional speed control method having the above configuration, in order to track the material, a switch circuit is required to connect and disconnect the material detector and the droop characteristic circuit, and furthermore, tracking malfunctions may occur. There is a risk of load imbalance leading to a trip state due to overload. In addition, when material gets caught in both motors, one motor becomes subject to constant speed control while the other motor exhibits drooping characteristics, resulting in problems such as load imbalances except under specific load conditions. There is.

In addition, as another speed control method, each speed regulator 1 of the electric motors M ₁ and M ₂ configured as shown in FIG.
It has also been proposed that motors 6 and 16 are configured to have drooping characteristics, respectively, so that the load is not concentrated on one of the motors.

However, according to this type of speed control method, it is extremely difficult to maintain the line speed at a target value.

Therefore, in a line speed control system using multiple electric motors that repeats this type of mechanical coupling and non-coupling, it is necessary to maintain a stable load balance regardless of whether the material is mechanically coupled or not. It is required to be able to control the line speed so that it can be maintained at the target value at all times.

[Purpose of the invention]

An object of the present invention is to achieve constant speed control of the line speed with a simple circuit configuration, and to maintain stable load balance at all times, and to achieve this at low cost through mechanical coupling and non-contact. The object of the present invention is to provide a speed control method for multiple electric motors that repeats coupling.

[Key points of the invention]

The speed control method for multiple electric motors according to the present invention provides a speed setting signal to each electric motor via a speed regulator and a torque regulator, and a speed detection signal detected via a speed detector provided in the electric motor. In a speed control system for multiple motors configured to perform speed control by feedback to speed regulators, a droop characteristic circuit is connected to each speed regulator, and a speed setting signal supply line is connected to these speed regulators. A line speed regulator that uses the speed setting signal as a target value is connected in parallel to the motor, and the output value of the speed detector provided in each motor is input to adjust the low-speed operation state according to the load fluctuation of each motor. A low-speed side priority circuit for detection is provided, and the output signal of this low-speed side priority circuit is input to the line speed regulator, and the output of the line speed regulator is set so that the actual speed value of the motor in the low-speed operation state becomes the set value. The speed setting signal is added to the speed setting signal supply line to make the line speed match the target value.

That is, in the present invention, when a plurality of electric motors are mechanically coupled and uncoupled due to materials and the line speed fluctuates, the speed regulator is provided with drooping characteristics and the low speed operating state of the electric motors is detected. By providing a line speed regulator that receives the output signal of the low-speed side priority circuit as input, and operating the line speed so that the line speed matches the target value according to the load condition of the motor,
It is possible to realize speed control of multiple electric motors that can always control the line speed constant and maintain stable load balance.

[Embodiments of the invention]

Next, an embodiment of the speed control method for multiple electric motors according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is a circuit diagram showing an embodiment of the speed control method according to the present invention. For convenience of explanation, the same reference numerals are given to the same components as those of the conventional control circuit shown in FIG. 1, and detailed explanation thereof will be omitted. That is, in this embodiment, the electric motor 10 is controlled via the speed regulator 16 and the torque regulator 18, the speed of the electric motor 10 is detected by the speed detector 20, and this detected speed value is fed back to the speed regulator 16. This configuration is the same as the conventional control circuit shown in FIG. However, in this embodiment, each electric motor
Droop characteristic circuits 28 and 28 are connected to the speed regulators 16 of M ₁ and M ₂ , respectively, and a line speed regulator 34 is connected in parallel to the speed setting signal supply line for each of the speed regulators 16 and 16. Furthermore, the output signals of speed detectors 20, 20 provided for each of the electric motors M ₁ and M ₂ are connected to a low speed side priority circuit 36, and the output terminal of this low speed side priority circuit 36 is connected to the line speed regulator 34. It is connected to the input end of the

Next, regarding the operation of the speed control circuit of this embodiment configured in this way, the operation explanatory diagrams of the materials shown in FIGS. 3 to 5 and the operation waveform diagrams of the motor shown in FIGS. 6 and 7 will be explained. This will be explained with reference to.

Now both drive roll 12 and idle roll 1
4, the electric motors M ₁ and M ₂ are both at the point shown in FIG. 7.
A ₁ has the speed characteristic, and the speed setting values for the motors M ₁ and M ₂ are values [speed commands] that compensate for no-load torque loss. That is, the speed setting value in this case is a value obtained by adding the correction output of the line speed regulator 34 to the speed setting signal.

Then, when the material 22 is caught between the drive roll 12 and the idle roll 14 driven by the electric motor M ₁ as shown in FIG. 3, only the electric motor M ₁ moves at the speed at point B ₁ in FIG. characteristics and the speed decreases. The actual speed value of the motor M ₁ is detected by the low speed side priority circuit 36 and fed back to the line speed regulator 34, and the speed command is set to the motor by comparing the actual speed value of the motor M ₁ with the speed setting value.
given to M ₁ and M ₂ . That is, to explain this state based on FIG. 7, the motor M ₁ shifts to the speed characteristic at point B ₂ , and the motor M ₂ shifts to the speed characteristic at point A ₂ .

Furthermore, as _shown in _FIG .
Both _M2 share the load torque and shift to the speed characteristics of point _C1 . As a result, the line speed regulator 34 operates so that the speeds of the electric motors M ₁ and M ₂ detected by the low-speed side priority circuit 36 match the set values, and finally become a speed command, and the speeds of the electric motors M ₁ and M 2 are adjusted to match the set values. ₂ is point C ₂
Shift to the speed characteristics of

Then, from the above state, the material 22 is connected to the electric motor M ₁
When the motor M 1 passes through the drive roll 12 driven by and reaches the state shown in FIG. 5, the motor M ₁ has only no-load loss torque and shifts to the speed characteristic at point A ₃ . Therefore, the load torque is applied only to the electric motor _M2 , and the electric motor _M2 shifts to the speed characteristic at point _B3 . As a result, the actual speed value of electric motor _M2 is changed to the low speed side priority circuit 3.
6 and fed back to the line speed regulator 34, and a speed command is given to the motors _M1 and _M2 by matching the actual speed value of the motor _M2 with the speed setting value. That is, to explain this state based on FIG. 7, the motor M ₂ shifts to the speed characteristic at point B ₂ , and the motor M ₁ shifts to the speed characteristic at point A ₂ .

After that, the material 22 advances further and the electric motor M ₁ ,
When the drive rolls ₁₂ , 12 driven by M2 are removed, both the electric motors _M1 and _M2 have only no-load loss torque, and the speeds of the electric motors _M1 and _M2 shift to the speed characteristics at point _A2 . As a result, the line speed regulator 34 operates so that the speeds of the electric motors M ₁ and M ₂ detected by the low-speed side priority circuit 36 match the set values, and finally become a speed command, and the speeds of the electric motors M ₁ and M ₂ is point A ₁
Shift to the speed characteristics of

In this way, according to the circuit of this embodiment, the sixth
In the operating state where the load fluctuates as shown in the figure, the electric motors M ₁ and M ₂ can maintain the line speed at the set value while properly maintaining the load balance in either case.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the speed control method for multiple electric motors according to the present invention, a droop characteristic circuit is connected to the speed regulator of each electric motor without providing a material detector, and a droop characteristic circuit is connected to the speed regulator of each electric motor. By providing a low-speed side priority circuit and a line speed regulator in the connected speed setting signal line, the line speed can be reliably set to the target value even when the load torque fluctuates due to mechanical coupling or non-coupling of the motors depending on the material. In addition, the load balance can be maintained stably. Therefore, the speed control method of the present invention has a simpler configuration than conventional methods, and can stabilize the balance between line speed and load easily and at low cost.

Furthermore, the speed control method according to the present invention allows a computer to maintain the functions of some of the circuits that implement this (for example, the low speed side priority circuit and the line speed regulator), thereby making it possible to control the speed of this type of electric motor. It is possible to have versatility as

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a control circuit diagram showing a conventional speed control method for multiple electric motors, FIG. 2 is a speed control circuit diagram showing an embodiment of the speed control method for multiple electric motors according to the present invention, and FIGS. 3 to 5 is an explanatory diagram showing a state in which multiple electric motors are mechanically coupled or uncoupled by materials, FIG. 6 is a waveform diagram showing load torque sharing characteristics of multiple electric motors shown in FIG. 2, and FIG. FIG. 3 is a waveform diagram showing speed control characteristics of multiple electric motors shown in FIG. DESCRIPTION OF SYMBOLS 10... Electric motor, 12... Drive roll, 14... Idle roll, 16... Speed regulator, 18... Torque regulator, 20... Speed detector, 22... Material, 24... Material detector, 26... Material tracking circuit, 28...
Drooping characteristic circuit, 30... switch circuit, 34... line speed regulator, 36... low speed side priority circuit.

Claims (1)

[Scope of Claims] 1. A speed setting signal is supplied to each motor 10 via a speed regulator 16 and a torque regulator 18, and a speed detection signal detected via a speed detector 20 provided in the motor is In a speed control system for multiple electric motors configured to perform speed control by feedback to a regulator, a droop characteristic circuit 2 is provided for each speed regulator.
A line speed regulator 34 whose target value is the speed setting signal is connected in parallel to the speed setting signal supply line connected to these speed regulators, and a speed detector provided in each of the motors. A low-speed side priority circuit 36 is provided which inputs the output value of and detects the low-speed operating state according to the load fluctuation of each motor, and inputs the output signal of this low-speed side priority circuit to the line speed regulator, and controls the line speed. The speed of multiple electric motors, characterized in that the output of the regulator is added to the speed setting signal supply line so that the actual speed value of the electric motor in a low speed operation state becomes the set value, so that the line speed matches the target value. control method.