JPH0221524A - Operating device of switch - Google Patents

Abstract

PURPOSE:To prevent the generation of high frequency waves by connecting in series a resistance and a capacitor in parallel to a series circuit of a changeover switch, a closing coil, and a field effect type transistor(FET). CONSTITUTION:In parallel to a series circuit of a changeover switch 3, a closing coil 4, and a field effect type transistor 5, a resistance 20 and a capacitor 21 are connected in series. And when the FET 5 is in the ON condition for a specific time T after the changeover switch 3 is closed, the making current flows to the closing coil 4 and a part of the current flows to the series circuit of the resistance 20 and the capacitor 21, to charge the capacitor 21. Moreover, when a maintenance current flows to the closing coil 4 to maintain the switch in a closed condition by the ON and OFF operation of the FET 5 after the switch is turned on, a temporary voltage drop is generated at the AC power source side following a starting delay of the secondary side inductive voltage of a transformer when the FET 6 is turned on, but this voltage drop is suppressed by supplying with the charged voltage of the capacitor 21. Consequently, a superposition of a high-frequency wave component to the secondary side voltage of the transformer can be prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention operates a switch by exciting a closing coil provided in a DC power supply circuit that converts AC power output into DC using a rectifier. The present invention relates to a switch operating device for closing the switch and supplying a holding current to the closing coil to maintain the switch in the closed state.

(Prior Art) A conventional operating device for this type of switch has a configuration as shown in FIG. In FIG. 2, 1 is an AC power supply, 2 is a rectifier that converts the output of this AC power supply 1 into DC, and on the DC side of this rectifier 2 there is a switch 31 and a closing coil 4 of a switch (not shown), the details of which will be described later. Field effect transistors (hereinafter simply referred to as FETs) 5 are connected in series, and are controlled on and off by a gate circuit.

Further, a flywheel diode 6 is connected in parallel to the series circuit of the open/close switch 3 and the closing coil 4, and the FET
A surge protection varistor 7 is connected between the source and drain of the transistor 5.

On the other hand, 8 is a gate circuit that provides a gate signal to FET 5, and this gate circuit 8 has a diode 8 connected to the gate of FET 5.
An unstable multi-by-break 8A provides a holding gate signal that is periodically turned on and off via diode 8-1, and a closing gate signal that turns on FET 5 for a certain period of time when the open/close switch 3 is closed is sent to FET 5 via diode 8-4. It is provided with a delay circuit 8B that provides a signal to the gate of the circuit. Unstable multi-by-break 8A is CMOS inverter 8-14°8-1
5.8-16, a diode 8-2.8-3, a capacitor 8-20, a resistor 8-7, and a variable resistor 8-13 to make the oscillation duty cycle variable. Furthermore, the delay circuit 8B is a CMOS inverter 8-17.8-1.
8.8-19, Zener diode 8-6, diode 8
-5, capacitor 8-21 and resistor 8-9.8-10
．． It is composed of 8-11.8-12.

In this case, the delay circuit 8B is connected so that when the on-off switch 3 is closed, the DC side voltage of the rectifier 2 is inputted via the resistor 8-11. Further, the output signal of this delay circuit 8B is on when the on-off switch 3 is in the open state, and the output signal is off when a predetermined time T has elapsed after the on-off switch 3 is closed. In addition, 8-8 is FET
This is a resistor provided between the gate and source of No. 5.

Next, the operation of the conventional switch operating device configured as described above will be explained with reference to the time chart shown in FIG.

When the open/close switch 3 is open (section a), the FE
Regardless of the gate signal of T5, the closing coil 4 is in a non-energized state, and therefore the switch (not shown) is open. Further, the output signal of the delay circuit 8B is in an on state.

In such a state, when the on-off switch 3 is closed at time to, the FET 5 is in an on state for a certain period of time T after the on-off switch 3 is closed, that is, the FET 5 is turned on from the delay circuit 8B.
Since it is turned on for a period of time due to the gate signal applied to the gate of
flows, and the switch is closed at time t1. And t2
At this point, that is, when a certain period of time T has passed since the open/close switch 3 was closed, the unstable multi-break 8A is activated.
An on/off holding gate signal is applied to the gate of the FET 5, and an intermittent current flows through the closing coil 4 as the FET 5 turns on and off. In this case, the excitation current flowing through the closing coil 3 is reduced to a holding current that is a fraction of the closing current determined by the on/off duty ratio of the holding gate signal, and this holding current holds the switch in the closed state.

Furthermore, when the open/close switch 3 is opened at time t3, the excitation current of the closing coil 4 becomes zero, and the state returns to the first section a.

In this way, when the switch is turned on, FET5 is connected to gate circuit 8.
Gate control is performed by a delay circuit 8A, and after the switch is closed, gate control is performed by an unstable multi-by-break 8B to maintain the closing operation and closed state of the switch.

(Problem to be Solved by the Invention) However, in a switch operating device with such a configuration, when the switch is in the holding state, the FET repeats on and off operations in a very short cycle, so When a small-capacity transformer 1, such as a voltage transformer, is installed, a voltage waveform distortion occurs in which a high frequency component is superimposed on the sine waveform of the secondary output of the transformer.

This phenomenon occurs when FET5 operates at a very high speed.
This is because the rise of the induced voltage on the secondary side of the transformer is delayed when the transformer is turned on, resulting in a temporary voltage drop and an overshoot due to transient phenomena during recovery.

For this reason, if the amplitude of the high frequency component superimposed on the sine waveform on the secondary side of the transformer is large, the peak value of the voltage waveform on the secondary side of the transformer will also be large, and therefore the effective value of the entire waveform will be high. If instruments are connected to the secondary side of the transformer, errors may occur in the indicated values of the instruments, and high frequency components become induced noise, so this 71! If the circuits of other elements are commonly connected to the source, there are problems such as malfunctions.

In the present invention, when the switch is in the holding state, the FET is turned on,
It is an object of the present invention to provide a switch operating device capable of suppressing a voltage drop on the secondary side of a transformer caused by off control and preventing the generation of high frequency waves caused by this.

[Structure of the Invention (Means for Solving the Problems)] In order to achieve the above object, the present invention provides a method for turning on a switch provided via a switch on the DC side of a rectifier that converts AC power output into DC. a coil, a field effect transistor provided in series with the closing coil, and controlling the field effect transistor to be turned on for a certain period of time after the opening/closing switch is closed to supply the current necessary to close the switch. The closing coil is energized, and after a certain period of time has elapsed since the opening/closing switch is closed, the closing coil is energized with a current necessary to turn on and off the field effect transistor and bring the switch into a holding state. In a switch operating device comprising a gate circuit, the opening/closing switch;
It has a configuration in which a resistor and a capacitor are connected in series in parallel to a series circuit of an input coil and a field effect transistor.

(Function) Therefore, in the switch operating device having such a configuration, when controlling the FET on and off when the switch is in the holding state, the secondary side of the transformer installed on the AC power supply side When the voltage drops, the voltage drop is suppressed by the charging voltage of the capacitor connected in parallel to the series circuit of the open/close switch, closing coil, and field effect transistor via a resistor, thereby eliminating voltage waveform distortion on the secondary side of the transformer. It becomes possible to do so.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the circuit configuration of a switch operating device according to the present invention, and the same parts as in FIG. 2 are shown with the same symbols. Note that the configuration and operation of the gate circuit are the same as those of the conventional circuit, so a description thereof will be omitted. In Figure 1, 1
is an alternating current power source, and a small capacity transformer (not shown) is used for this alternating current power source 1, and circuits for instruments and other elements are connected to the secondary side of the transformer. Reference numeral 2 denotes a rectifier that converts the output of the AC power supply 1 into DC. On the DC side of the rectifier 2, an on/off switch 31 is turned on by a closing coil 4 of a switch (not shown) and a gate circuit 8 similar to the conventional circuit.

FETs 5 which are turned off are connected in series.

Further, a flywheel diode 6 is connected in parallel to the series circuit of the open/close switch 3 and the closing coil 4, and the FET
A surge protection varistor 7 is connected between the source and drain of the transistor 5.

In this embodiment, in such a switch operating device, the on/off switch 3. A resistor 20 and a capacitor 2 are connected in parallel to the series circuit of the input coil 4 and the field effect transistor 5.
1 are connected in series.

In the switch operating device having such a configuration, when the FET 5 is in the ON state for a certain period of time T after the on/off switch 3 is closed, a closing current flows through the closing coil 4 and a portion of the current flows through the resistor 20 and It also flows through the series circuit of the capacitor 21, and the capacitor 21 is charged. After the switch is closed, the FET 5 turns on and off, causing a holding current to flow through the closing coil 4 and holding the switch in the closed state.
When the FET 5 is turned on, a primary voltage drop occurs due to the delay in the rise of the secondary side induced voltage of the transformer on the AC power supply side, but this voltage drop is caused by the charging of the capacitor 21? It can be completely suppressed by replenishing the voltage with voltage, so there is no possibility of high frequency components being superimposed on the secondary voltage of the transformer.

Therefore, noise does not occur in the voltage waveform on the secondary side of the instrument transformer, etc., so there is no error in the indicated value indicated by the instruments, and there is also no possibility that the secondary side of the transformer is connected to the circuits of other elements. Malfunctions due to inductive noise can be avoided even when the inductive noise is connected.

[Effects of the Invention] As described above, according to the present invention, the voltage drop on the secondary side of the transformer of the AC power supply caused by the on/off control of the FET when the switch is in the holding state is suppressed, and the voltage drop caused by this is suppressed. It is possible to provide a switch operating device that can prevent the generation of high frequency waves.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a switch operating device according to the present invention;
FIG. 2 is a circuit configuration diagram of a conventional switch operating device, and FIG. 3 is a diagram showing a time chart for explaining the operation of the conventional device. 1... AC power supply, 2... Rectifier, 3.
... Open/close switch, 4... Closing coil,
5...FET. 6...Flywheel diode, 7...
...Varistor for surge protection, 8...Gate circuit, 20...Resistor, 21...Capacitor. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A closing coil of a switch is provided via an on/off switch on the DC side of a rectifier that converts an AC power output into DC, a field effect transistor is provided in series with this closing coil, and this field effect transistor is connected to the After the on-off switch is closed, the closing coil is energized with a current necessary to close the switch by performing on-control for a certain period of time after the on-off switch is closed, and when a certain period of time has elapsed after the on-off switch is closed, the field effect transistor is turned on. A switch operating device comprising: a gate circuit that energizes the closing coil with a current necessary to put the switch in a holding state through on/off control; A switch operating device characterized by having a configuration in which a resistor and a capacitor are connected in series in parallel to a series circuit.