JPH10208575A - Relay controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable pointing during on and off of a contact to be constant from a second or subsequent relay operation by providing a contact operation detecting circuit, calculating time up to on or off of the contact due to nonexcitation or excitation of a relay coil, and establishing timing. SOLUTION: A contact operation detecting circuit 16 connects an AC photo- coupler in parallel to a relay contact 2, and this output is wave-rectified by a resistor, a diode and a capacitor, is inputted to a transistor base, and is outputted from the transistor collector. The relay contact 2 initially inputs an output wave at a contact part during on and off to a microcomputer 15, that delay time (first time) is calculated by the microcomputer 15, and second and subsequent relay outputs are performed considering that delay time. Thereby, the second and subsequent relay outputs make a relay contact openable at an ideal timing regardless of relay individual fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a relay of electric equipment.

[0002]

2. Description of the Related Art A microcomputer is used in a control circuit section, and a means for controlling a heater is a method of controlling a heater without a coil.
If an electrical device that uses a general relay that has no special function as an operating element when the contact instantaneously turns ON and OFF in response to excitation and the relay output timing aimed at just before the AC zero crossing is one pattern In the variation of each relay, the ON and OFF of the contacts are performed after passing the AC zero cross, and there is a problem that an arc is generated when the contacts are turned OFF and the contact life cannot be satisfied.

For example, as a countermeasure, the polarity of the contact is alternately turned on and off, or the contact is randomly opened and closed regardless of the AC zero cross.

[0004]

In the above conventional method,
Even if the polarity is changed alternately, the influence of the arc when the contact is turned off is large and may be affected by noise. In addition, it is complicated to randomly open and close the contacts, and in this case, there is also a problem that noise is affected.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a contact operation detecting circuit for operating the ON / OFF timing of a relay contact just before an AC zero crossing. The non-excitation of the relay coil, the contact by excitation, and the time until ON and OFF are calculated to determine the timing.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, an AC photocoupler is connected in parallel to a relay contact, the output is shaped by a resistor, a diode, and a capacitor, input to the base of the transistor, and output from the collector of the transistor. A contact operation detection circuit is provided so that the relay is turned on and off first.
The output waveform of the contact portion at this time is input to the microcomputer, the delay time (first time) is calculated by the microcomputer, and the second and subsequent relay outputs are performed in consideration of the delay time.

[0007] With the above configuration, the ON and OFF points of the contacts are fixed from the second and subsequent operations of the relay irrespective of the individual variations of the relay.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a relay drive circuit according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a relay contact operation detecting circuit, FIG. 3 is a flowchart for determining a relay output timing by a microcomputer, and FIG. Is a signal waveform of each section showing an example when the relay is OFF.

In FIG. 1, a load drives a heater 3 through a contact 2 of a relay, and a power supply unit lowers the voltage by a transformer 4 to make it DC by a rectifier circuit 5 and smoothes the output by a capacitor 6. It is further smoothed by a capacitor 8 through a constant voltage circuit 7 for relay. This is used as a power source for driving the relay, the emitter of the transistor 11 is connected to the high potential side, the collector is connected to the low potential side through the relay coil 10 from the collector, and the control circuit unit 15 comprising a microcomputer is connected.
To output a relay signal output to the base of the transistor 11 to turn on and off the relay. The Zener diode 9 is for back electromotive force protection by the relay coil 10, the resistor 12 is a bias resistor for surely turning off the transistor 11, and the resistor 13 is for limiting the base current. The power source for driving the relay is used as the power source for the control circuit unit 15 through the constant voltage circuit 14 for the control circuit. The signal is input from both ends of the relay contact 2 to the microcomputer 15 through the contact operation detecting circuit 16. A signal synchronized with the AC zero cross from the AC power supply 1 through the AC synchronization signal detection circuit 17 is input to the microcomputer 15. The microcomputer 15 calculates and determines the relay drive timing from the relay signal output, the contact operation detection signal, and the AC zero cross synchronization signal.

FIG. 2 shows an example of a relay contact operation detecting circuit 16, in which a light emitting portion of an AC photocoupler 19 is connected in parallel to the relay contact 2, and an emitter is connected to a reference point (GN).
Connect to D). Pull-up resistor 20 and diode 21
Is connected to the collector of the AC photocoupler 19, and a capacitor 22 is connected between the cathode of the diode 21 and GND. This output is input to the base of the transistor 24. The emitter of the transistor 24 is connected to GND, and the collector is connected to the pull-up resistor 25 for output. The resistor 23 is for surely turning off the transistor 24. As a result, the relay contact 2 is turned ON.
Then, the collector output of the transistor 24 becomes “L”, and when the relay contact 2 is turned off, the collector output of the transistor 24 becomes “H”.

FIG. 3 shows a flowchart of a method for determining the relay operation timing by the microcomputer, and FIG. 4 shows a change in the waveform of each part showing an example when the relay is OFF. Based on the signal synchronized with the AC power zero cross,
The period from the rise of this waveform to the next rise is defined as T1. Next, the time (T2) from the rising edge of the AC synchronizing signal waveform and the relay contact OFF are set so that the first (first) relay output OFF timing becomes the AC zero crossing portion.
It is set in advance that the target position is a portion before the time a from the AC zero cross.

The time T3 from the rise of the AC synchronizing signal waveform when the relay contact is turned off when the first relay OFF signal is output is read. The microcomputer turns off the relay for the first time (flow chart part 2
6) At time, the flowchart unit 27 first determines the four data, and if NO, the flowchart unit 28
And resets the relay output OFF timing T2 for the second and subsequent times, and proceeds to the flowchart section 32. If the determination in the flowchart section 27 is YES, the processing in the flowchart section 29 is performed and the relay output O
The FF timing T2 is reset and the flowchart section 30
Is determined, and if NO, the flow shifts to the flowchart section 32. If the determination in the flowchart section 30 is YES
If so, the process of the flowchart unit 31 is performed, the relay output OFF timing T2 for the second and subsequent times is set again, and the process proceeds to the flowchart unit 32.

The relay output ON timing is determined in the same manner as described above.

[0014]

According to the present invention, a relay contact operation detecting circuit is provided, and its output is input to a microcomputer and calculated, so that the second and subsequent relay ON and OFF operations are independent of the individual variations of the relay. The relay contacts can be operated at an ideal timing before the AC zero cross, so that damage to the relay contacts can be reduced, the life can be extended, and the influence of arc noise generated at the contacts can be reduced.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a relay drive circuit showing one embodiment of a relay control method of the present invention.

FIG. 2 is a circuit diagram of the relay contact operation detecting circuit.

FIG. 3 is a flowchart for determining the relay output timing.

FIG. 4 is a signal waveform diagram of each section showing an example when the relay is OFF.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Relay contact, 3 ... Heater, 15 ... Control circuit part (microcomputer), 16 ... Contact operation detection circuit.

Claims (1)

[Claims] A microcomputer is used for a control circuit unit, and a means for driving a heater includes a non-excitation coil,
In the relay control method in which the contacts are instantaneously turned ON and OFF in response to excitation, a contact operation detection circuit is provided to operate the ON and OFF timings of the relay contacts just before the AC zero crossing. A relay control method characterized in that the time until contact ON and OFF by excitation is calculated to determine the timing.