JPH08171843A - Relay controlling circuit - Google Patents

Abstract

PURPOSE: To extend the life of a relay circuit by making the timing to open or close a relay contact point be conformed to a zero crossing point of an a.c. current electric power source. CONSTITUTION: When a program instruction to close a relay point 4a of a relay circuit 4 is given to a microcomputer 5, at first a zero crossing point of an a.c. electric power source is detected from the output of a photocoupler 8. Further a correction time read out of a registor 15 is set as a time-up value in a liner to start the timer. At the time when the value of the timer reaches the time-up value, the timer is stopped. A relay controlling signal to start the relay circuit 4 is sent out of an output port 6 and thus the timing to open or close of the relay contact point of the relay circuit is conformed to the zero crossing point and relay control is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay control circuit which can prevent deterioration of a relay contact and extend the life of the relay contact.

[0002]

2. Description of the Related Art In electrical equipment and the like, when an inductance load or a large current load is opened and closed by a relay circuit that has mechanical contacts in a relay circuit that is frequently used such as on / off of an AC power supply, the contact between the contacts Due to the potential difference between the two electrodes, gas discharge generated in the gap between the two electrodes, such as glow discharge or arc discharge, causes contact welding or contact failure, which is a cause of shortening the life of the relay contact. Further, also in a relay control circuit such as a microcomputer or a sequencer for controlling the opening / closing of such a relay circuit, the timing for controlling the opening / closing of the relay circuit should be a necessary operation required for the electric device by a program. It has only been decided to do so. That is, the life of the relay circuit is not taken into consideration.

[0003]

Since the conventional relay control circuit is constructed as described above, the life of the contact of the controlled relay circuit is determined by the characteristic peculiar to the contact as long as it is used at the rated value. There has been a problem that means for extending the life of the contacts of the circuit have not been taken into consideration.

The present invention has been made to solve the above problems, and an object thereof is to provide a relay control circuit capable of extending the life of the contacts of the relay circuit.

[0005]

A relay control circuit according to the present invention is a relay control circuit for controlling a relay for turning on / off an AC load, and an AC power source applied to a relay contact for turning on / off the AC load. Of zero cross points, a time width detecting means for detecting a time width between the zero cross points detected by the zero cross detecting means, and a delay time detecting means for detecting an operation delay time when the relay operates. And, based on the time width between the zero cross points detected by the time width detecting means and the delay time detected by the delay time detecting means, for matching the opening timing or the closing timing of the relay contact with the zero cross point. Calculate the correction time amount of the output timing of the control signal that controls the relay A correction amount of time calculating means, characterized in that an output means for outputting a corrected said control signal output timing by the correction amount of time determined by calculating by the correction amount of time calculating means.

[0006]

The relay control circuit according to the present invention detects the zero cross point of the AC power source applied to the relay contacts,
A time width between the detected zero cross points, that is, a half cycle of the AC power supply is detected, and an operation delay time when the relay operates is further detected, and the relay is obtained from the time width between the zero cross points and the delay time. By calculating the correction time amount for the output timing with reference to the zero cross point of the control signal for controlling, by outputting a control signal for controlling the relay after the correction time has elapsed with reference to the zero cross point, Matching the timing of opening and closing the relay contact with the zero cross point, and suppressing gas discharge that occurs in the relay contact when opening and closing the relay contact, therefore glow discharge or arc discharge does not occur and the relay contact Prolong life.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an electric circuit diagram showing the configuration of the relay control circuit of this embodiment. In the figure, 1 and 2 are terminals connected to an AC power source, and 3 is an AC load. Reference numeral 4 denotes a relay circuit, which has a relay contact 4a that is opened and closed and an exciting coil 4b. One end of the exciting coil 4b is connected to the ground, and the other end is connected to the output port 6 of the microcomputer 5. Reference numeral 7 is a rectifying circuit for rectifying the AC voltage across the relay contact 4a, 8 is a photocoupler circuit, 8a is a light emitting diode on the input side of the photocoupler circuit 8, and 8b is a phototransistor on the output side of the photocoupler circuit 8.
The series circuit of the light emitting diode 8a and the current limiting resistor 9 is
It is connected to the DC output terminal of the rectifier circuit 7 that outputs the rectified DC voltage.

A load resistor 10 is connected between the collector terminal of the phototransistor 8b on the output side of the photocoupler circuit 8 and the DC power supply of the microcomputer 5. Then, the load resistor 10 and the phototransistor 8b
The connection point with the collector terminal of
Is connected to the input port 11. A RAM 12 is provided in the microcomputer 5, and registers 13, 14, 15 are set in the RAM 12. Register 13
Stores the time data indicating the half cycle of the AC power supply,
Further, the register 14 stores the correction data indicating the correction time for adjusting the output timing of the control signal for controlling the relay circuit 4. Further, the register 15 stores the value of the timer indicating the operation delay time of the relay circuit 4. The microcomputer 5 includes an RO (not shown).
M and the like are also provided, and a program for generation processing of correction data shown in FIG. 2 and a program for control signal output processing of the relay circuit shown in FIG. 5 are stored therein.

Next, the correction data generation processing operation of the relay control circuit will be described with reference to the flowchart of FIG. 2 and the timing chart of FIG. First, in step S1, initial settings are made and the input / output ports and registers of the microcomputer 5 are reset. As a result, the relay contact 4a of the relay circuit 4 is initially set to the open state. Next, in step S2, half cycle time data of the AC power supply is detected. The half cycle time data of the AC power supply is detected by the collector terminal of the phototransistor 8b on the output side of the photocoupler circuit 8 and the load resistor 10.
Since the signal output to the connection point with is a spike-shaped pulse signal as shown in (b) of FIG. 3, which becomes'H 'level in agreement with the zero-cross timing of the AC power supply, this spike It is obtained by detecting the interval between the pulse signals. As a result, the obtained half cycle time data of the AC power supply is stored in the register 13 in step S3.

Next, in steps S4 and S5, relay-on control for closing the relay contact 4a of the relay circuit 4 at the timing of the zero cross point learned from the spike-shaped pulse signal input to the input port 11 is performed. The signal is output from the output port 6. Further step S
At 6, the timer is started. The relay circuit 4 operates by the relay-on control signal and closes the relay contact 4a.
The closing timing of this relay contact 4a is fixed at the'H 'level as shown in FIG. It can be detected by the rising edge of the signal output to. After the rising edge is detected in step S7, the timer started in step S6 is stopped in subsequent step S8.

Since the value indicated by the stopped timer represents the operation delay time of the relay circuit 4, this operation delay time is known from the value indicated by the timer in step S9, and further in step S10. The value indicated by the timer is stored in the register 15. Then, in the next step S11, correction data indicating a correction time for adjusting the output timing of the control signal for controlling the relay circuit 4 is calculated and obtained. The correction data is obtained from the time data indicating the half cycle of the AC power supply stored in the register 13 as shown in FIG.
It is obtained by subtracting the operation delay time of the relay circuit 4 stored in 5. The correction data obtained as a result is stored in the register 14 in the next step S12.

After the correction data is obtained in this way, the relay circuit 4 is deenergized and the relay contact 4
a is again in the open state, and the value of the timer is reset.

Next, the output process of the relay control signal which can be turned on / off at the zero cross point using the correction data thus obtained will be described with reference to the flowchart of FIG. 4 and the timing chart of FIG.
The on / off timing of the relay circuit 4 in the program including the on / off of the relay circuit 4 required for the operation required for the electric device is processed as follows. That is, when a program command for closing the relay contact 4a of the relay circuit 4 is given to the microcomputer 5 as shown in (a) of FIG. Detect the zero cross point. Further, in the subsequent step S22, the obtained correction data is read from the register 15 by the timer, the correction time is set as a time-up value, and the timer is started in step S23. Then, in the subsequent step S24, it is determined whether or not the value of the timer has reached the time-up value, and in step S24, the timer is stopped when the time-up value is reached. The time t1 in (b) of FIG. 5 indicates the time when the time-up value is reached. Proceeding to step S26, which is shown in FIG.
A relay control signal for operating the relay circuit 4 is output from the output port 6 as shown in FIG. 5C shows the time point when the relay circuit 4 is actually turned on / off by the relay control signal, and as a result, FIG.
As shown in (f), it operates at the zero cross point A of the AC power supply.

[0014]

As described above, according to the present invention, the timing of opening or closing the relay contact is made to coincide with the zero cross point of the AC power supply, so that the gas discharge generated at the relay contact is suppressed and the relay contact is suppressed. Has the effect of extending the life of the.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing a configuration of a relay control circuit according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a correction data generation process in a relay control circuit according to an embodiment of the present invention.

FIG. 3 is a timing chart for explaining a process of generating correction data in the relay control circuit according to the embodiment of the present invention.

FIG. 4 is a flowchart showing an output process of a relay control signal in the relay control circuit according to the embodiment of the present invention.

FIG. 5 is a timing chart illustrating an output process of a relay control signal in a relay control circuit according to an exemplary embodiment of the present invention.

[Description of symbols] 3 AC load 4 Relay circuit (relay) 4a Relay contact 5 Microcomputer (delay time detection means, correction time amount calculation means, output means) 7 Rectifier circuit 8 Photocoupler circuit (zero cross detection means, delay time detection) means)

Claims (1)

[Claims] 1. A relay control circuit for controlling a relay for turning on / off an AC load, and a zero-cross detecting means for detecting a zero-cross point of an AC power source applied to a relay contact for turning on / off the AC load, and the zero-cross. Between the time width detecting means for detecting the time width between the zero cross points detected by the detecting means, the delay time detecting means for detecting the operation delay time when the relay operates, and the zero cross point detected by the time width detecting means. Of the output timing of the control signal for controlling the relay to match the opening timing or the closing timing of the relay contact with the zero cross point based on the delay time detected by the delay time detecting means and the delay time. A correction time amount calculation means for calculating the time amount and the correction time amount calculation means A relay control circuit, comprising: an output unit that outputs the control signal whose output timing is corrected according to the correction time amount obtained by calculation.