JP3996066B2 - Excitation control circuit for non-excitation brake - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetically actuated brake, and more particularly to an excitation control device for a non-excitation actuated brake.
[0002]
[Prior art]
In general, in a motor with an electromagnetic brake known as a brake motor, the brake is actuated by turning off the power, that is, de-energizing, to perform a rapid stop.
[0003]
In FIG. 3, a rectifier circuit composed of diodes D1 and D2 is connected to the power source side of the magnetic contactor MC, and an auxiliary contact of the electromagnetic contactor MC is inserted between the diode and the brake.
[0004]
[Patent Document 1]
Japanese Patent Application No. 2002-258832
[Problems to be solved by the invention]
The circuit shown in FIG. 3 is a measure against the problem of delay in brake operation time because the contacts between the diodes D1 and D2 and the brake B are disconnected by the contact of the magnetic contactor MC.
[0006]
However, the circuit configuration becomes complicated, and when the distance between the magnetic contactor MC and the motor M is large, the cost of wiring wires and the construction cost are required.
[0007]
Further, as a drive control circuit for the motor M, there is one using an inverter as shown in FIG. In this method, an inverter INV is inserted between the magnetic contactor MC1 and the motor M to perform soft start and soft stop when the motor M is started and stopped.
[0008]
In this case, since the output of the inverter INV decreases at the time of starting and stopping, the brake B cannot be operated by the output of the inverter INV. Therefore, the power source of the brake B is branched from the power source side of the inverter INV, and a relay RY and an electromagnetic contactor MC2 that respond to the operation of the inverter INV are provided for power supply control to the brake B.
[0009]
As a result, the circuit configuration associated with the inverter INV becomes considerably complicated.
[0010]
The present invention has been made in view of the above points, and an object thereof is to provide an excitation control device for a non-excitation operation type brake having a stable operation and a simple circuit configuration.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
Excitation of a non-excitation actuated brake that operates a non-excitation actuated electromagnetic brake attached to the motor when the power is turned off, and releases the brake when the power is turned on. In the control device,
A current transformer for detecting an energization current of the motor;
Light emitting diodes connected in antiparallel, light emitting means connected in series to the current transformer and forming a light emission signal according to the output of the current transformer ;
A light receiving means for receiving a light emission signal from the light emitting means;
A brake energization circuit having a switching element with an appropriate input time constant, and when the light receiving means receives a light emission signal, turns on the switching element and supplies a brake release current to the brake;
Excitation control device for non-excitation brakes, characterized by
Is to provide.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a circuit configuration of an embodiment of the present invention. In FIG. 1, a portion surrounded by an alternate long and short dash line is configured as a unit including a motor with a brake, and is used by being connected to a secondary side of an electromagnetic contactor MC that turns on and off the motor. That is, this unit is provided with motor power terminals U, V, W and circuit power terminals u, v. When this connection is made, the unit becomes operable.
[0013]
In the unit, a non-excited operation brake B is mechanically connected to the motor M, and the brake B is excited during the driving operation of the motor M to be in an inoperative state. When power supply to the motor M is stopped, the power supply to the brake B is stopped and the motor M is stopped by the operating force of the brake B.
[0014]
The brake B is energized and stopped by turning on and off a field effect transistor FET as a switching element. The field effect transistor FET is turned on and off by detecting the presence or absence of a current flowing to the motor M by the current transformer CT and operating the photocoupler PH according to the detection output. In response to the operation of the photocoupler PH, the field effect transistor This is done by turning the FET on and off.
[0015]
In the photocoupler PH, since two light emitting diodes LED are connected in antiparallel on the light emitting side, when an alternating current is applied from the current transformer CT, the two light emitting diodes LED alternately emit light, The generated light is given to the light receiving transistor PT. Thereby, the light corresponding to the full-wave rectified signal of the alternating current flowing through the current transformer CT is given to the light receiving transistor PT. The light receiving transistor PT energizes the brake B with the field effect transistor FET turned on.
[0016]
A constant voltage power supply circuit is formed by two diodes D1, D2, a resistor R1, an electrolytic capacitor C, and a Zener diode ZD as an operation power supply for the brake B by switching of the field effect transistor FET. The signal is applied to the field effect transistor FET through the light receiving transistor PT of the photocoupler PH.
[0017]
When the light receiving transistor PT of the photocoupler PH responds to an optical signal from the light emitting diode LED of the photocoupler PH connected to the secondary circuit of the current transformer, a voltage signal is applied to the gate G of the field effect transistor FET to turn it on. . The field effect transistor FET has a time constant determined by the resistor R2 connected to the gate of the field effect transistor FET and the gate capacitance Cg of the field effect transistor FET, and the on / off operation is performed according to the time constant. If this capacity Cg is not sufficient, a capacitor having an appropriate capacity may be added.
[0018]
In the circuit of FIG. 1, VZ1 and VZ2 are arresters for protecting each element used in the circuit from a high voltage.
[0019]
2A to 2D show voltage and current waveforms at various parts in the circuit of FIG. 2A and 2B show the voltage and current of the motor M. FIG. The motor voltage rises and maintains a constant value when the electromagnetic contactor MC is turned on, and gently falls when the electromagnetic contactor MC is turned off. On the other hand, the motor current rapidly increases when the magnetic contactor MC is turned on and then settles to a constant value, and immediately falls when the magnetic contactor MC is turned off.
[0020]
2 (c) and 2 (d) show the current and voltage of the brake B. The current of the brake B rises gently when the electromagnetic contactor MC is turned on, and immediately falls when the electromagnetic contactor MC is turned off. Then, the voltage of the brake B rises quickly with some gentleness when the electromagnetic contactor MC is turned on, and falls with an impulse voltage when the electromagnetic contactor MC is turned off.
[0021]
(Modification)
The semiconductor elements such as the photocoupler PH and the field effect transistor FET in the above embodiment may be replaced with other elements having the same function.
[0022]
【The invention's effect】
As described above, the present invention detects the motor current in the motor with a brake and applies it to the photocoupler to operate the switching element. Therefore, the auxiliary contact of the electromagnetic contactor is not used as in the prior art, and the motor Even if an inverter is used as the power source, a brake power source branched from the motor power source is not required, and a stable brake operation can be realized with a simple configuration.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a timing chart showing changes in voltage and current of a motor M and current and voltage of a brake B in the circuit of FIG. 1;
FIG. 3 is a connection diagram of a brake motor using a conventional electromagnetic contactor with an auxiliary contact.
FIG. 4 is a power supply system diagram of a brake motor using a conventional inverter as a motor power supply.
[Explanation of symbols]
M Motor B Brake MC Magnetic contactor RY Relay CT Current transformer D Diode ZD Zener diode PH Photocoupler LED Light emitting diode FET Field effect transistor R Resistance C Electrolytic capacitor

Claims (3)

Excitation of a non-excitation actuated brake that operates a non-excitation actuated electromagnetic brake attached to the motor when the power is turned off, and releases the brake when the power is turned on. In the control device,
A current transformer for detecting an energization current of the motor;
Light emitting diodes connected in antiparallel, light emitting means connected in series to the current transformer and forming a light emission signal according to the output of the current transformer ;
A light receiving means for receiving a light emission signal from the light emitting means;
A brake energization circuit having a switching element with an appropriate input time constant, and when the light receiving means receives a light emission signal, turns on the switching element and supplies a brake release current to the brake;
An excitation control device for a non-excitation actuated brake characterized by comprising: The excitation control device for a non-excitation brake according to claim 1,
The light emission means is an excitation control device for a non-excitation actuating brake having at least a pair of light emitting elements connected in antiparallel to each other. In the excitation control device of the non-excitation operation brake according to claim 1,
The switching element is an excitation control device for a non-excitation operation brake, which is a field effect transistor.

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