SU1367142A1 - Shaper of signal of voltage passing through zero - Google Patents

Abstract

The invention relates to a pulsed technique, in particular to electronic switching devices at zero crossing, and is intended to control power electronic switches, such as thyristors, symmetrical triode thyristors, in electric drive devices, electric heating, and other areas of AC power control. The purpose of the invention is to avoid interference with the operation of the former, simplifying its implementation in integrated design and reducing the number of DC sources necessary for its operation. The shaper contains current limiting elements 1–4, diodes 5 and 6, inverter 7, key transistor 8, control and input bus lines 9 and 10, output bus 11, and 12 and 13 dc sources. When the input voltage of the inverter 7 reaches a certain value, the inverter opens and the transistor 8 closes. This state is maintained for the entire duration of the control signal on bus 9, since zero, and even more positive, its value increases the input current of the inverter 7 and the degree of its opening. 2 hp f-ly, 1 ill. 12 -0 WITH 4 Yu in //

Description

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The invention relates to a pulsed technique, in particular to electronic switching devices at a zero-level intersection, and is intended to control power electronic switches, such as thyristors, symmetrical triode thyristors, in electric drive devices, electrical heating and other areas of variable-frequency power control. current.

The aim of the invention is to avoid interference with the operation of the former, simplifying its implementation in an integrated manner and reducing the number of DC sources necessary for its operation.

The drawing shows the scheme

ripple or alternating input on bus 10 to zero.

For the variant shown in the drawing, a formatatap in which pnp type transistors are used, the power supply bus 12 and the control signal on bus 9 have a positive potential relative to bus 13. If pnpr transistors are used in the former, the bus 12 and the signal on bus 9 must have a negative polarity with respect to bus 13, and the polarity of turning on the diodes is reversed (relative to that shown in the drawing).

Consider the first mode of operation.

When fed to the bus 9 control

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The shaper contains the first 1, second 2, third 3, and fourth 4 current-limiting elements, the first 5

proposed shaper.

accurate to provide the input current of the inverter 7, which keeps it in the on state, a low level output 25 is generated at the output of the inverter 7. It closes the key-hole transistor 8 and stops the flow of current from the bus 12 of the direct current source to the output bus 11. The magnitude of the potential of the control signal necessary to provide this mode of operation (.1 depends on the ratio of the resistances of the first to second 6 diodes, inverter 7, key transistor 8, busbars 9 and 10 of the control and input signals, output bus 11, first 12 and second 13 buses of the DC source, the first input of the inverter 7 connected to the first bus 12 of the DC source, inverter information input 7 is connected to the first output of the first current-limiting element 1 and through the second current-limiting element 2 nd bus 9 of the control signal, the output of the inverter 7 is connected to the base of the key transistor 8, the second output of the first current limiting element J is connected to the input signal bus 10, the second input the inverter 7 through the second diode 6 is connected to the second bus 13 of the DC source and through the current

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first, second and third current-limiting elements, the amplitude of the input signal and the input characteristic of the inverter.

The shaper operates in the second mode if on the bus 9 the control signal has a zero potential relative to the bus 13 or a potential not sufficient to ensure that the inverter is turned on. When the potential of the alternating limiting element 4 is approached — with a bus 10, a 45 or pulsing signal, the diodes are connected to the bus with 13 opposite electrodes.

Shaper has two modes of operation,

The first mode is characterized by a permanently closed state of the key transistor 8 at any polarity and amplitude of the input signal on the bus 10. The second mode of operation of the driver is characterized by periodic opening of the key transistor 8 and applying current to the load of the driver at the times corresponding to the amplitude approximation

first, second and third current-limiting elements, the amplitude of the input signal and the input characteristic of the inverter.

The shaper operates in the second mode if on the bus 9 the control signal has a zero potential relative to the bus 13 or a potential not sufficient to ensure that the inverter is turned on. As the potential of the alternating shape on the bus 10 approaches the zero level, the input current of the inverter and the current through the inverter decrease, the potential at the output of the inverter increases,

opening the key transistor 8. A current flows through the driver to the driver and, if its load is a control semiconductor gate, it will be switched on at the very beginning of the supply voltage period. In this case, there will not be an abrupt change in the current in the load of the valve, accompanied by electronic noise.

With a further increase in the amplitude of the input signal on bus 10 (when using a driver in: devices operating in AC networks, the input voltage can be used as the input voltage), the input current of the inverter increases, it opens, and the potential at the output decreases. the inverter and the closing of the key transistor 8,

Let us consider two possible modes of changing the input signal: an increase in the potential of the bus 10 relative to the I3 bus and a decrease in this potential.

If the potential of bus 10 increases, then the current through elements 1 and 3 increases and, consequently, the voltage drops across element 3, diode 6 and element 4, if it contains only a resistor, current is flowing from bus 10 to the mud 13. Fall the voltage on the diode 6 displaced in the forward direction with increasing current through it increases slightly. Therefore, increasing the voltage drop across the element 3 increases the potential difference at the input of the inverter.7, opening and closing the transistor 8, If the current limiting element 4 to reduce the power consumption is made in the form of series-connected resistors and a diode connected oppositely diode 6, then at a positive potential of the bus 10, the current through the element 4 does not flow, the voltage drop across the diode 6 is less and the inverter starts to open at a slightly lower potential of the bus 10. The inverter is turned on and 7 and the closed state of the transistor 8 are maintained during the entire period of the positive potential on the bus 10 and do not depend on the level of the control signal on the bus 9, since both at zero and at its positive value the inverter is open applied to its information input potential difference on the element 3 and the diode 6.

If the potential of bus 10 decreases with - after crossing the zero level, the current flowing through the current limiting element 1 lowers the potential of the information input of the inverter to a level whose minimum is determined by the voltage drop on the straight-line diode 5. Secondary The point of the power supply circuit of the inverter 7, which is connected to the common point of the diode 6 and the current-limiting element 4, is shifted to the region of negative potential, since the diode 6 is shifted in the opposite direction, and the inverter current flows through the element 4 to the bus 10. The potential difference s between this point and the inverter informa- tsionnm input is the input voltage of the inverter, and upon reaching op redeleynogo values inverter 7 is opened and transistor 8 is closed. This state is maintained throughout the entire period of the negative potential on the I / O bus, regardless of the action of the control signal on the bus 9, since its zero value, and all the more positive, increases the input current of the inverter and the degree of its opening.

Claims (1)

1. A voltage zero crossover signal generator comprising an inverter, a key transistor, first and second current-limiting elements, first and second diodes, a control bus and an input signal bus, a first and second DC source, and the first input of the inverter is connected to the first bus of the DC source, the information input of the inverter is connected to the first output of the first current-limiting element and through the second current-limiting element to the control signal bus, the output of the inverter is connected to the ba The second key transistor, characterized in that, in order to avoid interference with the driver and simplify it, the third and fourth current-limiting elements are additionally introduced, the second output of the first current-limiting element is connected to the input signal bus, the information input of the inverter is connected through a parallel-connected first diode and the third current-limiting element is connected to the second bus of the DC source, the second input of the inverter is connected via the second diode to the second bus of the DC source and through the fourth current-limiting 51367142 6 element - with the input signal bus, instruction, as the current-limiting diodes are connected to the second element; a resistor is used, not a constant current source different-3. The former according to any one of the electrodes, and the second diode due to the fact that It has a low impedance for an inverse-current reduction of power consumption, torus relative to this bus, the key-current-limiting element contains th transistor is connected between the output-series-connected resistor busbar and one constant-current busbar diode, the diodes of the first, second current, 10 o and the third current-limiting elements included oppositely Shaper shaper according to claim 1, about the first diode, and the diode of the fourth due to the fact that, for the purpose of the limiting element, minimization of the number of elements of the counter-in relation to the second diode.