RU1795533C - Bridge-type inverter - Google Patents

Abstract

Usage: the invention relates to electrical engineering and can be used in secondary power sources. SUMMARY OF THE INVENTION: The inverter comprises first, second, third, and fourth switching elements forming a bridge inverter. The first and second switching elements are made in the form of thyristors with control through thyristor optocouplers. The third and fourth switching elements are made on bipolar transistors, which are controlled by matching transformers. The use of bipolar transistors as the third and fourth switching elements simplifies the inverter circuit without affecting the remaining parameters of the device. 2 ill.

Description

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. The invention relates to a converter technique and can be used in the development of direct current to DC converters of a given frequency, power amplifiers, secondary power supplies.

Voltage inverters are known which are designed according to a single-phase bridge circuit, each rack of which consists of either single thyristors or transistors. The main disadvantage of thyristor inverters is the need to have additional nodes of artificial switching, which leads to a decrease in the reliability of their operation. A drawback of transistor inverters is the need to generate high-power control signals, which complicates the control circuit of such inverters and, therefore, reduces the reliability of their operation.

Known bridge transistor DC / DC Converter, containing four switching elements, shunted by reverse diodes, an output transformer, series control circuits connected to the control inputs of these switching elements, a master oscillator, to the output terminals of which are connected two resistive circuits from evetodiodov optron pairs of the corresponding sequential control circuits (prototype). The undoubted advantage of the prototype is the lack of winding products in the control system and the possibility of remote (optical) control, which greatly expands the functionality of the prototype. The disadvantage of the prototype is a large number of sequential control circuits, which

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greatly complicates the control circuit and reduces its reliability.

The purpose of the invention is to increase the reliability of the bridge inverter a by simplifying the control circuit.

The bridge inverter comprises by simplifying the control circuit.

The bridge inverter contains the first 6, second 8, third 7 and fourth 9 switching elements, shunted by reverse diodes 10, -11, 12 and 13, the first power terminals of the first 6 and second 8 of which are connected to the first input terminal + Ip connected through the first and the second sequential control circuit of the first resistors 1 and 14, the photothyristors 2 and 15, 3 and 16 of the first 2-24 and 15-23 and the second 3-22 and 16-25 optocouplers and the second resistors 4 and 17 with control inputs respectively, of the first and second switching elements, the second power terminals of which are connected respectively, through the third 7 and fourth 9 switching elements with the second input terminal — Ip output, transformer 1.9, the oscillator 20, to the output terminals of which are connected via a resistor two serial circuits of LEDs 22 and 23, 24 and 25, respectively, of the first optocoupler of the first a sequential control circuit and a second optocoupler of a second serial control circuit, as well as a matching transformer 26, 27, is primary, the winding of which is connected to the output of the master oscillator either directly or more through an amplifier, and the secondary windings are connected to the control inputs of the third and fourth switching elements, respectively, made on transistors 7 and 9, while the first 5 and second 18 capacitors are connected between the connection points of the photo thyristors 2 and 3, 15 and 16 of the first and second optocouplers, respectively, of the first and a second sequential control circuit and second power terminals of the first and second switching elements, respectively, made on thyristors 6 and 8.

Figures 1 and 2 show a circuit diagram of a bridge inverter and voltage diagrams explaining the principle of its operation.

The following symbols are adopted in the drawing: 6 and 8 - thyristors; 7 and 9 - transistors; 10. 11, 12 and 13 are reverse diodes; the first resistor 1, the photothyristor 2 of the first optocoupler, the photothyristor 3 of the second optocoupler, the second resistor 4 form the first sequential control circuit. The first resistor 14, the photo-thyristor 15 of the first optocoupler, the photo-thyristor 16 of the second optocoupler form a second series

control circuit; 19 - output transformer; 20 - master oscillator; 21 - limiting resistor; 5 and 18, respectively, the first and second capacitors; 23 and 24 - LEDs, respectively, of the first

an optocoupler of both a first and second sequential control circuit; 22 and 25 are the LEDs of the second optocouplers of the first and second sequential control circuit, respectively; 26 and. 27 - matching

transformers. A master oscillator (GG) 20 generates bipolar pulses, for the case under consideration, with a duration equal to the half-periods of the output voltage of the converter. The output 20 of points a and b in Fig. 1 is connected to the primary windings of transformers 26 and 27 to control the transistors 7 and 9 lbs directly, or through a preamplifier (not shown in Fig. 1) and through a resistor 21 to the input circuits of the optocouplers (on figure 1 is a series-connected LEDs 22, 23 and 24, 25). Photo thyristors 2, 3, 15 and 16, being outputs of optocouplers

2-24.3-22.15-23.15-23.16-25. are essentially outputs of CS. The bridge inverter operates normally, i.e. 6, 9 work in one half-cycle, 7, 8 in the second. Figure 1 shows a diagram when

each bridge inverter rack consists of a thyristor and a transistor.

In Fig. 2, Uy is the voltage at the 3G output and the inputs of transformers 26.27 and optocouplers; b, 9 - currents through thyristor 6, transformer

19 and transistor 9; i, 8 - currents through a transistor 7, a transformer 19 and a thyristor 8; Uc5 is the voltage shape across capacitor 5; UCIB- voltage across capacitor 18; 11ts- voltage at the output of the transformer 19.

The circuit operates as follows. The master oscillator 20 generates bipolar pulses Uy of the same duration. With a positive polarity Uy and t: O, the LEDs 22 and 23 open and simultaneously their photothyristors 3 and 15, as well as the transistor 9. At this moment (t 0), the capacitor 5 is charged in the previous interval to The DCS circuit (see Fig. 2c) starts to quickly discharge through the photo-thyristor 3, the resistor 4, the control electrode - the cathode of the thyristor 6. The thyristor 6 switches from the closed state to the open state and the formation of a positive voltage half-wave at the load begins (see Fig.Zz).

At the same moment (t 0), since the photo-thyristor 15 is open and the transistor 9 starts charging the capacitor 18 through + Un, the resistor 14, the photo-thyristor 15, the capacitor 18, the emitter-collector of the transistor 9, is Un (see fig.2d) . After charging the capacitor 18 to Un, the thyristor 15 closes and turns off the 18th type.

In the next half-cycle Uy, the transistor 7 and the other group of LEDs 24, 25 and their photo-thyristors 2 and 16 are unlocked and bit 18 starts at 16.17, the control electrode is the cathode of thyristor 8, which transfers 8 from the closed to the open state. From this moment t, the formation of the negative half-wave UH begins (see Fig. 2a, d, d, h). At the same moment (t), the charge СЗ begins along the circuit + Un.Resistor 1, photo-thyristor 2, capacitor 5, emitter-collector of transistor 7, - Op. In the next period, in each half-cycle, the processes in the circuit will be repeated.

If it is necessary to control the output voltage of the inverter, it is possible to use known methods, for example, changing the conductivity time of transistors 7 and 9.

Known methods can be used to eliminate through-current mode.

Obviously, the turning on times of thyristors 6 and 8 are determined by the moments

Claims (1)

The claims A bridge inverter containing the first, second, third and fourth switching elements, shunted by reverse diodes, the first power terminals of the first and second of which are connected to the first input terminal connected through the first and second serial control circuits of the first resistors, photothyristors, first and second optocouplers and second resistors with control inputs, respectively, of the first and second switching elements, the second power terminals of which are connected respectively through the third and fourth switching connecting elements with a second input terminal, an output transformer whose secondary winding is connected to the output terminals, and the primary winding is connected to the connection points of the first and third, as well as the second and fourth switching elements, to open the phytotrietors 3 and 16, and the turning off times of the thyristors 6 and 8 are determined by the turn-off times of transistors 7 and 9, respectively. Photothyristors 3 and 16 they are locked after the discharge of the corresponding capacitors 5 or 18, and the shutdown of the photo thyristors 2 and 15 are determined by the moments when the voltage of 5 and 18 reaches the value Un. The time of bit 5 and 18 is set by resistors 4 and 17 and is selected so that during the time of bit 4 and 18 the thyristors have time to turn on. These times are in the order of 100-150 μs. Charge times 5 and 18 are determined by resistors 1 and 14, respectively, and usually less than a half period is selected so that 6 and 8 have time to restore their locking properties before the end of the half period. As the master oscillator 20, any generator circuit of bipolar rectangular pulses can be used. Thus, the control of the inverter is greatly simplified since it excludes two reinforcing decoupling units; manufacturability is improved since transformer equipment is simplified. All this leads to an improvement in weight and dimensions, an increase in operational reliability, manufacturability and ease of adjustment and replacement of elements. a generating generator, to the output terminals of which are connected two serial circuits of LEDs, respectively, of the first optocoupler of the first serial control circuit and the second optocoupler of the second serial control circuit, as well as the first optocoupler of the second serial control circuit and the second optocoupler of the first serial control circuit, first and second capacitors, characterized in that, in order to increase reliability by simplifying the circuit, a matching transformer is introduced, the primary winding of the cat The second one is connected to the output of the master oscillator, and the secondary windings are connected respectively to the control inputs of the third and fourth switching elements made on biopolar transistors, while the first and second capacitors are connected between the connection points of the photo thyristors of the first and second optocouplers, respectively, of the first and second 71795533 8 consecutive control circuits, but the first and second switching elec- tric power leads of the corresponding connections made on thyristors. Uc C7.8 s, 8 U ,. 6 -i t 9