SU471668A1 - Device for switching the AC circuit - Google Patents

Description

one

The invention relates to circuit switching devices at the points where the source voltage passes through zero and can be used in automation devices as output amplifiers.

Devices are known for switching an AC circuit containing two parallel-connected thyristors, two successive chains formed by a resistor, a diode, a storage capacitor, and a switch.

In the proposed device, an additional diode is connected to the power circuit of each thyristor, and between the power supply terminals there is a series circuit formed by a key and a parallel chain, each branch of which consists of a series circuit formed by a resistor, a storage capacitor and a diode, to the anode of which the cathode of the diode is connected connected to one of the thyristors through a diode connected by the cathode to the anode of the diode of the connected branch, one branch being connected to the key pole of the diode cathode, the other and - capacitor plate, and the resistors connected to the output terminal device and a control electrode of the thyristor, the anode of which is connected to a pole switch, coupled through a resistor to the junction point of the storage capacitor resistor of said n branch.

and the control electrode of the second thyristor - through a resistor with the anode of the first thyristor.

FIG. 1 shows the basic electrical circuit of the proposed device; in fig. 2 - voltage diagrams.

The device contains thyristors 1, 2, storage capacitors 3, 4, diodes 5-10, resistors 11-14, switch 15, load 16.

In the initial state, the thyristors 1, 2 are closed, since with the open key 15, there are no signals on their control electrodes. When the key 15 is closed, for example, at time ti (see Fig. 2), due to the positive half-wave voltage, the capacitor 3 is charged through resistor 11, diode 5 and key 15, but the thyristor 1, despite the fact that time / i, a signal is applied to its control electrode, does not open, since the apolu tion of this half wave is negative relative to its anode. Storage capacitor 4 is not charged. Somewhat later than the time t corresponding to the passage of a positive half-wave through zero, a positive voltage begins to increase at the anode of the thyristor 1.

The parameters of the charging circuit are chosen in such a way that the storage capacitor 3 continues to discharge in a circuit: resistor 12 is a transition of the control electrode-cathode of the thyristor 1-diode 6.

When the storage capacitor 3 is discharged, a positive signal is applied to the control electrode of the thyristor 1, which opens the thyristor 1, the last stop, which is a low resistance for this half-wave of alternating voltage. During the same half-wave, from the time t the storage capacitor 4 is charged and a positive signal is applied to the control electrode of the thyristor 2, but the thyristor 2 remains closed, since the voltage of this half-wave is negative with respect to its anode. The storage capacitor 4 is charged along the circuit: switch 15 — diode 10 —resistor 14.

At time / 3 when the voltage of the anode of the thyristor 2 is changed, the latter opens, since the discharge of the storage capacitor 4 still continues, which ensures the passage of a positive signal through the control electrode of the thyristor 2.

Thus, the thyristors 1, 2 when the key 15 is closed, at any moment of time are turned on at very low voltages at their anodes, i.e., this device switches the circuit when the voltage passes through zero.

When the key .15 is opened, the control signals are removed from the control electrodes of the thyristors I, 2. Thyristors 1, 2 are closed when the polarity on their power electrodes is changed and the voltage and load becomes zero.

Similarly, the device commutes an alternating current circuit of various frequencies. When the frequency and voltage form of the power supply network vary within sufficiently wide limits, the device parameters practically remain unchanged.

five

Subject invention

A device for switching an alternating current circuit when a power supply voltage passes through an ilul containing two oppositely connected thyristors, two consecutive circuits formed by a resistor, a diode, a storage capacitor, and a switch, characterized in that

5 in order to simplify it, reduce power consumption and eliminate overvoltages, an additional diode is connected to the power circuit of each thyristor, and between the terminals of the power supply includes a sequential circuit formed by a key and a parallel chain, each branch of which consists of a series circuit formed a resistor, a storage capacitor and a diode connected to one of the three stresses through a diode connected by a cathode to the anode of the diode of the connected branch, one branch connected to the pole of a cell ca diode cathode, other - capacitor plate, and the resistors connected to the output terminal

0 of the device controlling the thyristor electrode, the anode of which is connected to the key pole, is connected via a resistor to the connection point of the storage capacitor and resistor of the branch, and the control electrode of the second thyristor is connected to the anode of the first thyristor.

and

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