JP3413547B2 - Power supply for electromagnetic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an energizing efficiency by improving a power supply feeding method to an electromagnetic equipment such as an electromagnetic clutch, and an electromagnetic brake, lower the effective value of a energizing current, and make a coil and a snubber element small in size. SOLUTION: When the coil 23 of an electromagnetic clutch is to be energized, voltage from a commercial AC power supply rectified in full wave, is applied to the coil at the over exciting time when energization is started for the definite period of time so as to allow responsiveness at the time of starting to be enhanced. In succession, at the normal time, full wave rectified voltage whose conduction angle is controlled by a FET 25, is applied to the coil. Since voltage is rectified in full wave, its effective value is small as compared with that of half wave rectification in the past, the exothermic of the coil 23 is thereby little. Besides, electromagnetic energy to be accumulated in the coil 23 at the time when electricity is turned off, is also little. Therefore, it is good enough that a varister 26 acting as a snubber element is made small in size.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic device used for supplying power to an electromagnetic clutch, an electromagnetic brake and the like widely used in various production machines, industrial robots and the like. Power supply to
It relates to a feeding device . 2. Description of the Related Art Some of the above-described electromagnetic devices are driven by a voltage other than a voltage obtained by rectifying a commercial power supply (voltage and current provided by a power company). FIG. 5 shows an example of a power supply circuit used in such a case, in which an electromagnetic clutch is used as an electromagnetic device (an electromagnetic brake can be similarly considered). This circuit is connected to a commercial power supply 1 on the input side of a bridge circuit 7 including diodes 2 to 5 and a thyristor 6. On the output side of the bridge circuit 7, a coil 8 of an electromagnetic clutch, which is one of the electromagnetic devices, and a varistor 9 as a snubber element are connected in parallel. The clutch coil 8 has an inductance component 10 and a resistance component 11. [0005] The gate of the thyristor 6 is connected to the output side of the full-wave / half-wave switching control circuit 12.
The current supplied to the load is switched between a full-wave current and a half-wave current. In the conventional circuit constructed as described above, the coil 8 of the electromagnetic clutch is used to operate an electromagnetic clutch (not shown) or to stop the operating electromagnetic clutch (negative operation). In the negative operation type, the thyristor 6 is controlled by the full-wave / half-wave switching control circuit 12, and at the start of energization, a fixed time of about 1 second (this period is called an overexcitation period). A current is supplied, and then a half-wave rectified current is supplied in a steady state (see the waveform diagram in FIG. 6). In the above operation, when the current supply to the coil 8 is turned off, the inductance component 10
Is absorbed by a varistor 9 as a snubber element. The above-described conventional power supply has the following problems. That is, since the voltage applied to the coil of the electromagnetic device in the steady state is a half-wave waveform, the effective value of the current is doubled as compared with the full-wave waveform, and the temperature rise of the coil becomes large. As a countermeasure to prevent this, it is inevitable to increase the winding diameter, and as a result, the size of the electromagnetic device is increased. Further, since the applied voltage supplied to the coil in a steady state has a half-wave rectified waveform, the current flowing through the coil cannot be controlled, and as a result, the surge power when the power is turned off cannot be reduced. SUMMARY OF THE INVENTION [0007] The present invention has been made to solve the above-mentioned problems of the conventional power supply device. In addition to being able to be set arbitrarily, the effective value of the current flowing through the coil can be reduced,
It is intended to provide a power supply device for an electromagnetic device. [0008] According to an aspect of the present invention, as means for solving the above problems, the power supply according to claim 1
In the invention of the power supply device , when the voltage is kept
During the steady state, and then applied during the overexcitation.
Power supply that applies a voltage lower than the
Is an electromagnetic clutch equipped with a rectified power
In a power supply device such as a rake,
A circuit that switches the threshold voltage that limits the fixed time
Monostable multivibrator having a conduction angle control
Supplies current to the load and supplies the first monostable
Power conducted in synchronization with the output signal of the multivibrator
-Detects positive and negative cycles of switch elements and commercial power
A photocoupler that outputs a detection signal
It is started at the timing of the detection signal of the
A second monostable multi-buy for determining the conduction angle of the switch element
It is characterized by having a brater . According to the present invention having the above-described structure, a voltage obtained by full-wave rectifying a commercial AC power supply at the time of overexcitation at the start of energization is applied to a coil of an electromagnetic device for a predetermined time. Responsibility improves because it is applied,
Thereafter, in a steady state, a full-wave rectified voltage whose conduction angle is controlled is applied. Energy saving operation is possible. Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are divided into three circuits, that is, a current supply circuit 13 for the coil, an overexcitation control circuit 14 and a timing control circuit 15 for the sake of convenience, but they are one circuit as a whole. Terminals A to E of these circuits are respectively connected to terminals having the same symbol. The description starts with the current supply circuit 13. The commercial power supply 16 has four diodes 17 to 20
Are connected to form a full-wave rectifier circuit 21. The output side of the full-wave rectifier circuit 21 is connected via a power switch 22 to a coil 23 of an electromagnetic clutch (24 is a winding resistor) and a power MOSF as a power switch element.
An ET (hereinafter referred to as FET) 25 is connected in series. A varistor 26 is connected to the coil 23 in parallel so as to absorb electromagnetic energy stored in the coil 23. A diode 27 is connected between a connection point between the coil 23 and the varistor 26 and a positive output terminal of the full-wave rectifier circuit 21. The commercial power supply 16 is connected in parallel with a series circuit of a resistor 28 and a diode 29 and a series circuit of a resistor 30, a switch 31 and a diode 32. The photodiode 29 of the photocoupler 33 is connected in parallel to the diode 29, and the photodiode 36 of another photocoupler 35 is connected in parallel to the diode 32 . First and second photocouplers 33, 3
The emitters of the fifth phototransistors 37 and 38 are connected to the input terminals of a waveform shaping inverter 39. The bases of the phototransistors 37 and 38,
Resistors 40 and 41 are connected between the emitters, and a resistor 42 is connected between the input terminal of the inverter 39 and the ground circuit. The collectors of the phototransistors 37 and 38 are connected to the terminals B and D, the output terminal of the inverter 39 is connected to the terminal C via the capacitor 43, and the power supply terminal is full-wave.
The positive output terminal of the rectifier circuit 21, that is, the power of the diode 48
Connected to sword terminal . [0019] The gate terminal of the FET 25 is connected to a resistor 44 in parallel, the resistor 45 is connected between the gate terminal and the pin A of FET 25. A resistor 46 is connected between the terminals A and B. A resistor 47 and a diode 48 are connected in series between the output side of the power switch 22 and the terminal B, and the cathode side of the diode 48 and the negative output terminal (ground circuit) of the full-wave rectifier circuit 21 are connected to each other. Between the Zener diode 49 and the capacitor
5 0 are connected in parallel. The overexcitation control circuit 14 will be described with reference to FIG. This circuit has a terminal D connected to the full-wave rectifier circuit 2 shown in FIG.
1, the positive output terminal , that is, the cathode terminal of the diode 48
To the output terminal of the transistor 66.
The resetter of the monostable multivibrator 67 shown in FIG.
Connected to the terminal. It has a timer function for limiting a predetermined time from the start of energization to the coil 23 of the electromagnetic clutch as a load. Between the positive line 51 connected to the terminal D and the negative line 52 of the ground circuit, a capacitor 55 and a resistor 56 are connected in series in a parallel circuit of a diode 53 and a resistor 54. A transistor 57 is provided between the capacitor 55 and the resistor 56.
The base is connected. The collector of the transistor 57 is connected to the positive line 51 via the resistor 58, and the emitter is connected to the negative line 52. The reference numeral 59 designates a monostable multivibrator. As illustrated, the power supply terminal (VCC) and ground point element in monostable multivibrator 59 (GND), trigger terminal, a reset terminal, a control terminal, a threshold terminal and discharge terminal and an output terminal is provided. The power supply terminal is connected to the positive line 51, and the ground terminal is connected to the negative line 52. The trigger terminal is connected to the connection point between the resistor 58 and the collector of the transistor 57 and the positive line 52 through the resistor 60.
It is connected to the. A resistor 61 is connected between the reset terminal and the positive line 51. The control terminal is connected to the negative line 52 via a capacitor 62, and the threshold terminal and the discharge terminal are connected to a capacitor 63.
Is connected to the negative side line 52 via the. A resistor 64 is connected between the threshold terminal and the positive line 51. The monostable multivibrator 59 starts a time limit (approximately 1 second) when there is an input to the trigger terminal, and sets the output terminal to high level. A resistor 6 is connected to this output terminal.
5 is connected to the base of the transistor 66. The collector of the transistor 66 is connected to the terminal E, and the emitter is connected to the negative line 52. Next, referring to FIG.
5 will be described. This circuit has terminals A, B, C and E
Is provided, and FET as a power switch element
25 (see FIG. 1). At the center is a monostable multivibrator 67. The monostable multivibrator 67 has exactly the same terminal also monostable multivibrator 59 described above, the power supply terminal to the terminal B, the ground pin is connected to the ground circuit. One end of each of the resistors 68 to 71 is connected to the terminal B. The other end of the resistor 68 is connected to one end of the resistor 73 together with the other end of the resistor 69 via the switch 72. Connected to poles. The other end of the resistor 73 and the other pole of the switch 72 are connected. And resistor 73
Is connected to the switch 74 by the monostable multivibrator 6.
7 is connected to the threshold terminal of
4, a series circuit of a switch 75 and a resistor 76 is connected in parallel. The control terminal of the monostable multivibrator 67 is connected to a ground circuit via a capacitor 77, and the threshold terminal and the discharge terminal are connected to a ground circuit via a capacitor 78. The trigger terminal of the monostable multivibrator 67 is connected to the terminal C, the reset terminal is connected to the terminal E, and the output terminal is connected to the transistor 80 via the resistor 79.
Connected to the base. The collector of the transistor 80 is connected to the terminal A, and the emitter is connected to the ground circuit. Next, the operation of the circuit (the whole circuit connecting the components shown in FIGS. 1 to 3) will be described. When the power switch 22 is turned on, the alternating current of the commercial power supply 16
1 and smoothed by a resistor 47, a diode 48 and a capacitor 50, and becomes a power supply (VCC) of the timing control circuit 15. Zener diode 49
Is for constant voltage. Next, the overexcitation control circuit 14 will be described. The capacitor 55 is charged with the current limited by the resistor 54, and the charging current causes the transistor 57 to charge.
Turns on. When the charging of the capacitor 55 is completed, the transistor 57 is turned off. The collector of the transistor 57 is connected to the trigger terminal of the monostable multivibrator 59. Since the input of the monostable multivibrator 59 is low active, it is triggered when the transistor 57 is turned on. Thus when the input signal enters the trigger pin, between the time constant (about 1 second) which is determined by resistor 64 and capacitor 63, the output of the monostable multivibrator 59 becomes high level, transistor capacitor
66 turns on. On the other hand, the trigger terminal of the monostable multivibrator 67 of the timing control circuit 15
Is detected by the two photocouplers 33 and 35, the polarity is inverted by the inverter 39, and a signal via the capacitor 43 is input. Here, since the power supply voltage VCC of the inverter 39 and the rising voltage of the transistor 57 are substantially equal, the monostable multivibrator 67 is reset, the output becomes low level, and the transistor 80 is turned off. FET2
Since the gate of No. 5 is connected to the power supply by the resistors 46 and 45, the gate of the No. 5 becomes high level, and the FET 25 is turned on. When the FET 25 is turned on, a DC voltage obtained by full-wave rectification of the commercial power supply 16 is applied to the coil 23, and the coil 23 is deactivated (in the case of a negative operation type electromagnetic device). That is, FE
T25 conducts in all the positive and negative cycles of the commercial power supply 16 (conduction angle 180 °, FIG. 4). This period is the overexcitation period. When the output of the monostable multivibrator 59 becomes low level, the transistor 66 is turned off and the monostable multivibrator 67 is released from the reset state. Next, a description will be given of the timing control circuit 15 which takes on and off timings of the FET in the steady state. When the photocoupler 33 is turned on by the polarity of the commercial power supply 16, the emitter voltage is as shown in FIG. This voltage is inverted in polarity by the inverter 39 and triggers the monostable multivibrator 67 via the capacitor 43. The output voltage of the monostable multivibrator 67 becomes a high level time constant (about 5 msec) determined by the resistors 69 and 73 and the capacitor 78. This corresponds to a quarter cycle when the power supply frequency is 50 Hz. When the power supply frequency is 60 Hz, it is 4.2 msec. In order to make the power applied to the clutch in a steady state constant even when the power supply frequency changes, the ON time constant of the monostable multivibrator 67 may be switched in accordance with the power supply frequency. Specifically, it is sufficient to switch between the resistors 69 and 73 and the capacitor 78. In this circuit, the switch 72 is turned on and off, and whether or not the resistor 68 is connected in parallel to the resistor 69 is controlled. I have to. During this steady period, the transistor 80 is turned on, so that the gate of the FET 25 becomes low level,
Therefore, it is turned off. Monostable multivibrator 67
Becomes low, the transistor 80 turns off and the FET 25 turns on. That is, 1/2 of the voltage of the commercial power supply 16 is applied to the coil 23 of the electromagnetic clutch, and the applied power is 1/4 that of the overexcitation.
become. However, this is only an example, and the time constant at this time can be set arbitrarily, so that the power applied to the coil 23 in the steady state can be set freely. In a negative-acting type electromagnetic device, it is possible to operate even at a power supply below the rated power in a steady state.
Energy saving operation becomes possible. Needless to say, the overexcitation time can also be set arbitrarily. When the waveform of the commercial power supply 16 is opposite to that of FIG. 4, the photocoupler 35 is turned on, and the emitter voltage of the phototransistor 38 becomes as shown in FIG. This voltage is inverted in polarity by the inverter 39 and triggers the edge stable multivibrator 67 via the capacitor 43. As a result, half the voltage of the commercial power supply 16 is applied to the coil 23. That is, the full-wave rectified DC voltage of the commercial power supply 16 is applied to the coil 23. Next, the operation of the snubber circuit will be described. While the power switch 22 is on and the FET 25 is on, the electromagnetic energy stored in the coil 23
When the switch 25 is turned off, the terminal voltage polarity of the coil 23 is reversed, and the power switch 22 and the coil 23
Current flows through the system path, and the electromagnetic energy is converted into heat energy by the winding resistance 24 of the coil 23. Power switch 22
Is off, the electromagnetic energy becomes maximum when the timing at the moment of turning off is the maximum of the power supply voltage,
An extremely large surge voltage is generated at both ends of the coil 23 . Since this voltage destroys the FET 25, the varistor 2
Absorb at 6. At this time, since the power switch 22 is off, no current flows through the diode 27. When operating as described above, the emitter voltage of the phototransistor 38 of the photocoupler 35 becomes as shown in FIG. 4 and the trigger input waveform of the monostable multivibrator 67 becomes as shown in FIG. With respect to this input, the output waveform is as follows. As a result, the drain voltage of the FET 25 and the voltage applied to the coil 23 are as shown in FIG. Next, application to a full-wave / half-wave switching system will be described. In this case, if the photocoupler 33 or 35 is deactivated, a voltage obtained by half-wave rectifying the commercial power supply is applied to the coil 23 of the electromagnetic clutch in a steady state. Further, by setting the time constant of the monostable multivibrator 67 to a half cycle (10 msec) when the power supply frequency is 50 Hz, the FET can be almost half the length of the commercial power supply.
25 can be turned on, so that the same operation as the conventional method can be performed. In the present embodiment, the photocoupler 35 is turned off by turning off the switch 31. When the switch 74 connected to the threshold terminal of the monostable multivibrator 67 is turned on, full-wave rectification is performed. When the switch 74 is turned off, the time constant becomes larger than that in full-wave rectification, so that half-wave rectification is performed. When the power supply frequency is 50 Hz, when the switch 75 is turned on, the resistor 76 is connected in parallel to the resistor 73, and the time constant is shortened. When the power supply frequency is 60 Hz, the switch 75
Turning off turns the time constant longer. By operating the switch 75 in this manner, even if the frequency of the commercial power supply fluctuates, the current supply to the coil 23 in a steady state can be controlled, so that it is not affected. Since the present invention is a power supply device for an electromagnetic device configured as described above, according to the invention of the device described in claim 1, full-wave rectification in a steady state By changing the conduction angle of the applied voltage and supplying the voltage to the coil of the electromagnetic device, the effective value of the current does not increase as in the conventional half-wave rectifier. Therefore, the heat generated by the coil is small,
The size of the coil and thus the size of the electromagnetic device can be reduced. Further, since the conduction angle of the power switch in the steady state can be arbitrarily set, it is possible to set the power applied to the electromagnetic device to be equal to or less than the rated power, thereby enabling energy saving operation. By setting the applied power in the steady state to the rated power or less, the surge power when the power is turned off can be reduced, and the snubber element can be made small and inexpensive.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a current supply circuit to a coil of an electromagnetic device according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing an overexcitation control circuit according to the embodiment of the present invention. FIG. 3 is a circuit diagram showing a timing control circuit in the embodiment of the present invention. FIG. 4 is a graph showing waveforms at various points during operation. FIG. 5 is a circuit diagram showing a conventional circuit. FIG. 6 is a graph showing an operation waveform of FIG. [Description of Signs] 13 Current supply circuit 14 Overexcitation control circuit 15 Timing control circuit 16 Commercial power supply 21 Full-wave rectification circuit 22 Power switch 23 Coil 25 FET 33 Photocoupler 35 Photocoupler 39 Inverter 59 Monostable multivibrator 67 Monostable multi Vibrator

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-52-76553 (JP, A) JP-A-3-12000 (JP, A) JP-A-62-144563 (JP, A) JP-A-10-107 164845 (JP, A) Shokai 56-115038 (JP, U) Shokai 4-97313 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16D 48/06 F16D 65 / 21 H02M 7/06

Claims (1)

(57) [Claims] [Claim 1] Voltage is applied for a certain period of time at the time of overexcitation at the start of energization
Then, in the steady state, the voltage applied during the overexcitation is
Full-wave rectification or half-wave of commercial power supply applying lower voltage
Electromagnetic clutch and electromagnetic brake with rectified rectified power supply
In a power supply device such as
Circuit for switching threshold voltage to time limit
First monostable multivibrator, by controlling conduction angle
A current is supplied to a load and the first monostable
A power switch that is turned on in synchronization with the output signal of the
Switch, detects positive and negative cycles of commercial power
A photocoupler that outputs a detection signal;
Activated at the timing of the detection signal, the power switch
Second monostable multivibrator for determining conduction angle of element
Electromagnetic clutch and electromagnetic brake
Power supply device such as key.