JPH01255499A - Motor controller - Google Patents

Abstract

PURPOSE:To re-start a device without stopping all the lines, by closing a switch when a motor is tripped by any reason and when the terminal voltage of the motor coincides with the output voltage of a thyristor converter. CONSTITUTION:When a DC motor 1M is stopped due to the fault of an overload or the like, then the DC motor 1M is pulled by material and is rotated at a line speed 26. When the motor is reset after the cause of the fault is avoided, then a contact 23 is closed by the reset, and field current 28 ia gradually increased. Along with this increment, the terminal voltage 29 of the DC motor is also increased, and when this value coincides with the output voltage 27 of a thyristor converter 8, then the output of coincidence signal is generated, and a contactor 1L is made, and the DC motor 1M is re-started.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a motor control device for driving a plurality of motors, and particularly relates to control at the time of restart.

(Prior Art) A thyristor Leonard device will be described as an example of a conventional electric motor control device with reference to FIG.

As shown in FIG. 3, the voltage command from the voltage setting device 1 is
The acceleration limiting circuit 2 converts the signal into a signal having a constant rate of change, and inputs the signal to a control amplifier 3 as a voltage reference signal.

On the other hand, a signal from a voltage detector 4 that detects a DC voltage is input as a voltage feedback signal to a voltage control amplifier 3, and is compared and amplified with a voltage reference signal to perform voltage control. The output of this voltage control amplifier 3 becomes a current reference signal, and the current control amplifier 5
The main circuit current is controlled by Furthermore, the output of the current control amplifier 5 is input as a phase control signal to the positive and negative side phase control circuits 7a and 7b selected by the torque direction detector 6 which selects the positive or negative side thyristor converter 8 depending on the torque direction. be done. The positive or negative side phase control circuit 7a or 7b selected by the torque direction detector 6 sends a gate signal to the positive or negative side thyristor of the thyristor converter 8,
The thyristor is turned on and the AC power supply 9 is controlled and rectified to output a DC voltage.

A DC motor nM (n is rectification) is connected to the output side of the thyristor converter 8. Note that although the number varies depending on the mechanical configuration of the process line, the explanation here assumes that n pieces are connected and driven. These DC motors I
M to nM are contactors IL for opening/closing/shutoff, respectively.
Through nL, protection circuit 1 for DC motor IM~n1lI
It is connected to the output side of the thyristor converter 8 and is driven.

On the other hand, the field circuits of the DC motors IM~nM also perform constant current control, but since all of these circuits are the same, these operations will be explained only for the circuit of the DC motor IM, and the others are the same, so their explanations will be given below. is omitted. On the other hand, in field current control, a field current reference signal from a current setting device 10 is input to a field current amplifier 11, and is compared with a field current feedback signal from a field current detector 12. The output of the magnetic current control amplifier 11 is sent as a gate signal to each thyristor in the thyristor converter 14 via the field phase control circuit 13 to control and rectify the AC power source 15.

Here, when the protection circuit 101 detects an overload or an overcurrent of the DC motor IM, the contactor IL is opened at the open contact 17 by the operation of the protection circuit 10L to protect the DC motor IM. The operation of contact 17 is protection circuit 10L.
I am using one that is retained until reset.

Regarding the field circuit and protective operation above, please refer to the DC motor 1M
Although we have only explained about the use of other DC motors,
The same applies to usage.

In addition, in the figure, the circuit between DC motors 2M to nM is indicated by a dotted line to indicate that the same circuit exists, and the field circuit is also omitted because the circuit within the dashed line is the same.
The field circuit between ~nM is also represented by a dotted line, indicating that the same circuit exists.

(Problem to be Solved by the Invention) However, when the above-mentioned conventional thyristor Leonard device is used to drive auxiliary equipment in a process line, one or more motors may be damaged due to the protection circuit of each motor due to a failure such as overload. When tripped and stopped, the line is usually not stopped. At this time, when attempting to restart the tripped auxiliary after removing the cause of the failure, the auxiliary drive motor is pulled by the line and rotates at approximately line speed, and only the induced voltage of the motor is generated, causing the armature to Since there is no voltage drop, there is a sudden change in starting current equivalent to this armature voltage drop, which may adversely affect the line material until the motor completes starting, or when a tripped auxiliary machine is being pulled on the line. In the case of a slip, the difference between the output voltage of the thyristor converter and the induced voltage of the motor becomes large depending on the rotation speed, resulting in an electromotive current at restart, causing a problem of tripping again.

Therefore, in view of the above-mentioned problems, the present invention changes the field current of the motor until the start-up is completed at the time of re-excitation after tripping of the motor, makes the dielectric voltage of the motor equal to the output voltage of the thyristor converter, and changes the torque after the start-up is completed. An object of the present invention is to provide a motor control device that returns a field current to a predetermined value at a rate of change that does not affect the line and completes starting.

[Structure of the invention]

(Means for Solving the Problems) Therefore, in order to achieve the above object, the present invention provides changing means for changing the field current of the electric motor, and terminals of the electric motor based on output signals from the changing means. change the voltage,
Comparison means for comparing the terminal voltage of the motor and the output voltage from the motor control device; switching means provided between the motor and the motor control device; and opening/closing operations of the switching means based on the output signal from the comparison means. Provided is a motor control device equipped with a field current control means.

(Function) In a device configured in this way, the terminal voltage of the motor is detected, the output voltage of the thyristor converter is also detected, and these detected terminal voltages of the motor and the output voltage of the thyristor converter are compared. do.

Then, when the terminal voltage of the motor matches the output voltage of the thyristor converter, a closing operation is performed with the opening/closing means, and the motor is restarted. At the same time, a part of the opening/closing means is required to be opened, the field strengthening signal is cut off, and the field strengthening signal becomes zero at a constant rate of change.

As a result, even if the electric motor trips for some reason, the entire line will not be stopped, and
Even when restarting, the line will not be adversely affected.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

Electric IM will stop. At this time, the contact 21 is opened and the contact 22 is closed due to the fall of the contactor IL. When the protection circuit 10L is reset at time t2, the contact 23 is reset.
is closed, and the field strengthening signal is inputted from the field strengthening setting device 24 through the rate circuit 25 to the field current control amplifier 11 at the rate of change set by the rate circuit 25, increasing the field current and causing direct current. The induced voltage of the motor IM increases and at time 5,
When the output signals of the voltage detector 4, which detects the output voltage of the thyristor converter 8, and the voltage detector 18, which detects the terminal voltage of the DC motor IM, match, a match signal is output from the comparator 18, and the contact 20 When closed, the contactor IL is turned on, the contact 21 is closed, the contact 20 is held, and the DC motor IM
is restarted, the contact 22 is opened by turning on the contactor IL, and the field strengthening signal is cut off, and thereafter the field current decreases at the rate of change set by the rate circuit 25 until the restart is completed at time t.

In a device configured in this way, first, the DC motor 1M fails at time t due to a failure such as overload (the protection circuit 10L operates).
When the contactor IL opens and stops at step 1, the DC motor IM is pulled by the material and rotates at the line speed 26. In this state, the armature current of the DC motor IM is 30
is zero due to the fall of the contactor IL, and the terminal voltage 29 of the DC motor IM is reduced by the armature voltage drop (equivalent to the induced voltage).

After removing the cause of the failure, when the failure is reset at time t1, the reset closes the contact 23, and since the contact 22 was already closed when the contactor IL fell, the field strength setting device 24 The magnetic strengthening signal is added to the field current control amplifier 11 via the rate circuit 25, and the field current 2
8 increases at a rate of change set by the rate circuit 25.

Along with this, the terminal voltage 29 of the DC motor also increases, and when this value matches the output voltage 27 of the thyristor converter 8 at time t3, that is, when the output values of the voltage detectors 4 and 8 match, the comparator 19 A coincidence signal is output, and contact 20 is closed (at this time, contact 17 is closed due to fault reset).

), and the contactor L L.

The contact 21 is closed when the contactor IL is closed.
The contact 20 is held, the contact 22 is opened, the field strengthening signal from the field strengthening setting device 24 is cut off, and the rate circuit 2
The field strengthening signal decreases toward zero at the rate of change set in 5.

At this time, the terminal voltage 29 of the DC motor LM also decreases, and due to the difference with the output voltage of the thyristor converter 8, the armature current 3
0 flows and generates torque to start driving the auxiliary equipment.

At time t4, the DC motor IM returns to its pre-trip state and enters normal operation, completing the restart.

At this time, the rate of change of increase/decrease in the rate circuit 25 is set to a value that does not affect the material. Furthermore, the time of change is selected so that it is larger than the time constant of the field, and the withstand capacity of the field due to the increase in field current during field strengthening is increased at time t2. From t4
This is not a problem since the period of time required for this is short (usually only a few seconds).

The above operation has been explained for one circuit for the DC motor 1M, but the operation of the circuits for the other DC motors 2M to nM is similar.

Also, a circuit for DC motors 2M to nM (including a field circuit).

) are also similar, so it is the same as in FIG. 3 - the dotted chain line and the dotted line represent the existence of similar circuits.

As described above, in this embodiment, after detecting a fault in the DC motor, the cause of the fault is removed and the fault is reset (time tz).
When this is done, the field current is increased so that it matches the output voltage of the thyristor converter (voltage during operation of other DC motors) and the terminal voltage of the DC motor to be restarted (induced voltage in this state), At the time when they match (time t3), the contactor is turned on, the DC motor is started, the field current is weakened from time t to t4, and the actual load is applied to restart, so it is possible to do this without affecting the line. can. Also, time t
2 to time t can be prevented from affecting the material by the rate circuit.

〔Effect of the invention〕

As described above, according to the present invention, when the DC motor driven by the thyristor Leonard device trips due to a failure or the like, the entire line is not stopped, and the restart is performed without any adverse effect on the line. This makes it possible to stabilize line operations and improve operating efficiency.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. FIG. 2 is a time chart showing the operation of the embodiment of the present invention shown in FIG. 1, and FIG. 3 is a conventional thyristor Leonard device. FIG. 1ton/DC motor Ratio ~ nL... Contactor... Voltage setter 4, 18... Voltage detector 8.14... Thyristor converter 9, 15...
・AC power supply 17.20-23...Contact 1
9... Comparator agent Patent attorney Nori Ken Chika Yudo Ken Daishimaru Figure 2

Claims (1)

[Claims] In a motor control device that drives and controls a plurality of electric motors, a changing means changes the field current of each of the electric motors, and a terminal voltage of the electric motor is changed based on an output signal from the changing means, and the terminal voltage of the electric motor is changed. a comparison means for comparing the terminal voltage and the output voltage from the motor control device; a switching means provided between the motor and the motor control device; A motor control device characterized by comprising control means for controlling opening and closing operations and controlling the field current.