JPS60101829A - Relay drive unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a relay driving device that drives a relay near the maximum value of an AC power supply voltage.

Conventional configurations and their problems In general, in relays with mechanical contacts, the power loss due to the contact resistance of the relay contacts is sufficiently smaller than the power loss due to the on-resistance of the semiconductor switching element, so large load currents cannot be achieved. It has the advantage of being able to flow heat and not requiring the use of a heat sink.

However, arc discharge occurs between the contacts when the load current is switched on and off, resulting in significant deterioration of the contacts, making it difficult to switch on and off frequently, and still having poor reliability.

OBJECTS OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a relay drive device that can open and close relay contacts near the maximum value of AC power supply voltage for inductive loads. be.

Structure of the Invention The relay driving device of the present invention comprises: a power synchronization signal generation means for generating a signal synchronized with zero volts of an AC power supply; an opening/closing phase input means for inputting a phase in which a relay contact opens or closes; and said power synchronization signal generation means. a control section having a drive phase determining means for inputting a synchronization signal from the synchronous signal and an opening/closing signal from the opening/closing phase input means and determining a driving phase of the relay contact; and a control section for driving the relay by an output signal from the control section 3. The relay drive means is configured to open and close the relay contacts near the maximum value of the AC power supply voltage.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which 1 is an AC power supply, 2 is a DC power supply, 3 is a load, 4 is a relay contact connected in series with the load 3, and 6 is a relay contact of the AC power supply 1. Power synchronization signal generation means for generating a signal synchronized with zero volts, 6 is a relay contact 4
7 is a control section consisting of a microcomputer, and 8 is a relay drive means for driving a relay by an output signal from the control section 7. The power synchronization signal generating means 6 is composed of a diode bridge 5a, resistors csb, sc, and a photocoupler 6d, and the opening/closing phase input means 6 is composed of a diode bridge 6a,
It is composed of resistors eb and ec, a photocoupler ad, and a capacitor 6e, and the relay driving means 8 includes a relay coil 8a,
A surge absorbing diode 8b1 is composed of a transistor 8c and a resistor 8d. The control unit 7 includes a CPU, I(O
M,,RAM.

It is composed of an input/output board and the like, and inputs the synchronizing signal from the power synchronizing signal generating means 6 and the opening/closing signal from the opening/closing phase input means 6 into the ROM. Inside, there is a drive phase determining means for determining the drive phase of the relay and outputting a drive signal. FIG. 2 shows a flowchart illustrating an example, and FIG. 3 explains the operation.

Next, the operation of the relay drive device configured as described above will be explained. As shown in the flowchart of FIG. 2, when the synchronization signal is input (step 1Q), the delay time is counted (step 11) L, and the value stored in the RAM is reached (
Step 12) and output or stop the drive signal (
Step 13).

In steps 14, 15 and 16, the time from when the drive signal is output or stopped until the change in the state of the open/close signal is input (drive signal ton, stop: toff) is measured, and in step 17 the next delay is determined. Calculate time. This delay time is the time ton (IJ syringe operation time), to
Compare ff (IJ Schiller return time) and the % cycle of the synchronization signal page 5 (corresponding to the cycle of AC power supply),
If the times ton and toff are shorter than the % period,
It is the value obtained by subtracting the time ton, toff from the % cycle, and if the time ton, toff is longer than the % cycle, the time ton, toff is calculated from 3//2 cycle of the synchronization signal.
is the value obtained by subtracting . In general, the operating time of a relay is ton
Since the late time toff and the late time toff have different values, the delay times determined by the above-described subtraction are also stored in the RAM as the delay time to1 for the time ton and the delay time t1 for the time toff.

As shown in FIG. 3, when the relay contact is closed, there is a delay time t from the synchronization signal C synchronized to zero volts of the power supply voltage a-b. drive signal d with a phase delayed by . and outputs the opening/closing signal e. The time ton until the fall of t is measured and the above calculation is performed to determine the delay time t≦ for the next time the contact is closed and store it in the RAM. On the other hand, when opening the relay contact, stop the drive signal at a phase delayed by the delay time t from the synchronizing signal C (Fig. 3 d1), measure the time toff until the rise of the opening/closing signal e, and then open the contact. Delay when opening 6
Determine the page extension time t4.

As described above, the relay drive device in the embodiment determines the drive phase of the relay so that the phase in which the relay contacts open and close is close to the maximum value of the AC power source by repeating the operation of the flowchart shown in FIG. Therefore, in the case of an inductive load, since the current becomes zero near the maximum value of the AC power supply, the occurrence of arc discharge that occurs when the relay contacts open and close can be significantly reduced. (In the case of an inductive load, opening the contacts at a point other than the zero phase of the current will generate a large back electromotive force, making arcing particularly likely.) In the embodiment of the present invention, the operating time and return time of the relay are measured each time the relay is opened and closed to determine the next delay time, but it is also possible to store them as predetermined values in the ROM.

Effects of the Invention As is clear from the above description, according to the relay drive device of the present invention, in order to open and close the relay contacts near the maximum value of the AC power supply, the arc that occurs between the contacts when opening and closing the inductive load is reduced. Discharge is suppressed, the life of the contacts is significantly improved, and the variation in life can be reduced by 7 pages, improving reliability. It is also possible to reduce the excitation current when turning on a transformer or the like.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a relay driving device showing one embodiment of the present invention, FIG. 2 is a flowchart of the same, and FIG. 3 is an explanatory diagram of the operation of the same device. 1...AC power supply, 2...DC power supply, 3
...Load, 4...Relay contact, 6...
. . . Power synchronization signal generation means, 6 . . . Opening/closing phase input means, 7 . . . Control unit, 8 . Name of agent: Patent attorney Toshio Nakao and 1 other person
2 Diagram

Claims (1)

[Claims] A power synchronization signal generation means for generating a signal synchronized with zero volts of the AC power supply, an opening/closing phase input means for inputting the open/close phase of the relay contact, and a synchronization signal from the power synchronization signal generation means and an opening/closing phase input means. a control section having a drive phase determining means for inputting an opening/closing signal and determining a drive phase of the relay contact; and a relay drive means for opening and closing the relay contact near the maximum value of the AC power supply voltage based on an output signal from the control section. Equipped with a relay drive device.