JP2002013567A - Control method of electromagnetic brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable shortening of brake operation time, without generating mechanical noise at the time of switching of an electromagnetic brake. SOLUTION: At step S1, after high frequency voltage is imposed on an electromagnetic brake coil, electric current which flows in a circuit is detected with current detector. Current response then is detected in step S2, and by using an ON gate signal, namely, a voltage command and a current value detected by the current detector, inductance L is computed at step S3, by a formula v=Ldi/dt. Next, at step S4, the inductance L computed at step S3 is examined for the period in which the inductance is changing or not, and if it is the period wherein the inductance L is changing, then at step S5 the electromagnetic brake is judged to be in switching operation. Then, if the electromagnetic brake is in switching operation, at step S6 current variation is made gradual and the mechanical noise generated at the time of switching of the brake is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic brake control method using a DC power supply.

[0002]

2. Description of the Related Art FIG. 5 is a schematic diagram illustrating the construction of an electromagnetic brake. In FIG. 5, reference numeral 1 denotes a rotating body, 2 denotes a movable iron piece and brake pad for applying an electromagnetic brake to the rotation of the rotating body 1, and 3 denotes a yoke. The yoke 3 has an electromagnetic brake coil 4
Is wound, and the brake is turned on / off depending on whether a DC voltage is applied to the coil 4 or not.

The electromagnetic brake coil 4 is shown in FIG.
Is connected to a DC power supply 5 via a switch 6, and this switch 6 is controlled by an ON / OFF command from a control unit 7. During this control, a step-like voltage as shown in FIG. 6B is applied to the electromagnetic brake coil 4. When such a step-like voltage is applied to the electromagnetic brake coil 4, there is a problem that a loud mechanical noise is generated because the opening and closing operation of the brake is sudden.

[0004]

In order to suppress the above problem, a switching element 6a made of a semiconductor element is used as the switch 6 as shown in FIG.
By applying a voltage having a pattern having a trapezoidal slope as shown in FIG. 7B to the element 6a, a sudden change in current is not applied to the electromagnetic brake coil 4 so that a large machine generated when the brake is opened and closed. Means for suppressing sound are taken.

[0005] In order to suppress the loud mechanical noise when the electromagnetic brake is opened and closed in this way, the slope of the change in the current flowing through the electromagnetic brake coil may be made gentle. However, in the method of opening and closing the brake with a specific voltage or current pattern, the timing of opening and closing the brake is not clear, so the slope must be gentle over the entire area of zero current → rated current, rated current → zero current, The time required to open and close the brake becomes longer, which causes a new problem that the dead time increases.

The present invention has been made in view of the above circumstances, and has as its object to provide an electromagnetic brake control method capable of shortening the brake operation time without generating mechanical noise when opening and closing the electromagnetic brake. Make it an issue.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a circuit in which a switching element is connected in series to an electromagnetic brake coil. When controlling the electromagnetic switching element by controlling the switching element, an inductance of the electromagnetic brake coil is calculated from a current response after applying a high-frequency voltage to the electromagnetic brake coil, and the calculated inductance is changed according to a change in the calculated inductance. The switching element is controlled so that the current flowing through the electromagnetic brake coil changes slowly.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the electromagnetic brake described above,
If the gap length of the magnetic circuit differs between when the movable iron piece is attracted and when the electromagnetic brake separates, the value of the inductance L of the brake coil also differs. From this, by applying the high-frequency voltage v to the electromagnetic brake coil and measuring the change in the inductance L from the relationship with the current i, which is the response, using the following equation (1), You will be able to see if you are in a state.

V = Ldi / dt (1) FIG. 1 is a schematic configuration diagram of an electromagnetic brake control circuit used in an embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a DC power supply. A series circuit of the electromagnetic brake coil 12 and the switching element 13 is connected. The switching element 13 is controlled as described later by a gate signal from the control unit 15 to which the detected value of the brake coil current detected by the current detector 14 is supplied.

FIG. 2 is a flowchart showing an electromagnetic brake control method in which the embodiment of the present invention is applied to an electromagnetic brake control circuit. In FIG. 2, a high-frequency voltage is first applied to the electromagnetic brake coil 12 in step S1.

To this end, a gate signal which is a voltage obtained by superimposing a voltage for flowing an opening / closing current from the control unit 15 to the electromagnetic brake coil 12 and a high-frequency voltage for measuring the inductance is supplied to the switching element 13. As shown in FIG. 3, the gate signal is created by comparing a signal wave obtained by superimposing a harmonic component on a DC component with a carrier wave, and provides an ON gate signal to the switching element 13 during a period of signal wave> carrier wave.

When the ON gate signal is supplied, the current flowing in the circuit is detected by the current detector 14. The current response at that time is detected in step S2, and the inductance L is calculated in step S3 using the ON gate signal, that is, the voltage command, and the current value detected by the current detector 14 in accordance with the above equation (1).

Next, it is checked in step S4 whether the inductance L calculated in step S3 is changing. If the inductance L is changing, the electromagnetic brake is opened and closed in step S5. When you are.
Then, a gentle current change and a period T _1, T ₂ shown in FIG. 4 at step S6 if the electromagnetic brake is in the opening and closing operation, suppress mechanical noise generated during brake closing.

[0014]

As described above, according to the present invention,
There is an advantage that the generation of mechanical noise when opening and closing the electromagnetic brake can be suppressed as much as possible, and the brake operation time can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electromagnetic brake control circuit used in an embodiment of the present invention.

FIG. 2 is a flowchart showing an electromagnetic brake control method in which the embodiment of the present invention is applied to an electromagnetic brake control circuit.

FIG. 3 is an explanatory diagram of a method for creating a gate signal for superimposing a high-frequency voltage.

FIG. 4 is an explanatory diagram of a current pattern in a case where a current gradient is made gentle only when an electromagnetic brake is opened and closed.

FIG. 5 is a schematic configuration diagram of an electromagnetic brake.

6A is a circuit configuration diagram when a step-like voltage pattern is applied to the electromagnetic brake coil, and FIG. 6B is a voltage waveform diagram showing the step-like voltage pattern.

FIG. 7A is a circuit configuration diagram when a voltage pattern having a slope is applied, and FIG. 7B is a voltage waveform diagram illustrating the voltage pattern having a slope.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... DC power supply 12 ... Electromagnetic brake coil 13 ... Switching 14 ... Current detector 15 ... Control part

Claims (1)

[Claims] When a DC current is applied to a circuit in which a switching element is connected in series to an electromagnetic brake coil, the DC current is detected, and the switching element is controlled in accordance with the detected value to control the electromagnetic brake. A switching element that calculates an inductance of the electromagnetic brake coil from a current response after applying a high-frequency voltage to the electromagnetic brake coil, and that a change in current flowing through the electromagnetic brake coil becomes gentle according to a change in the calculated inductance. Controlling the electromagnetic brake.