SU1543516A1 - Ac-to-dc voltage converter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power sources. The purpose of the invention is to expand the functionality and improve the power factor - due to the fact that between each phase and the zero bus network there are two single-ended rectifiers on different polarity transistors connected to their own loads, which ensures the loading of the network with a sinusoidal current. Due to additional loads, the functionality of the converter is expanded. 2 Il.

Description

The invention relates to electrical engineering and can be used in secondary power sources.

The purpose of the invention is to enhance the functionality and improve the power factor.

FIG. 1 is a circuit diagram of a converter; FIG. 02 is timing diagrams explaining it.

work

The converter contains a three-phase bridge thyristor rectifier 1, the output terminals of which are connected to the load 2, and the AC inputs through the primary windings of the current transformers 3-5 to the phase input terminals. Between each phase (input output and zero output included two single-ended rectifiers 6 and 7, made on opposite-transistors 8-10 and 11-13. The outputs of rectifiers 6 and 7 are connected

respectively, to the additional loads 14 and 15. The basic circuits of the transistors 8-13 are connected to the corresponding phase input terminals via control circuits 16-21, consisting of serially connected basic resistance and two parallel circuits. Each chain consists of two connected in series and according to photodiodes opto-pairs. The emitting diodes of these optocouplers, together with the emitting diodes of the optocouplers of the control circuit connected to another input phase output, form a series connection connected to the secondary circuits of the current transformer. In series with this emitting diode, the series-connected emitting diodes of the optocouplers of the respective control circuits of the reverse-conducting transistors are connected. Transformer

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current, to the secondary circuits of which the emitting diodes of optocouplers connected to the control circuits connected to the two phase input terminals are connected between the third input terminal and the corresponding input terminal of the rectifier

The Converter operates as follows.

In the time interval from the moment when the voltage Ux intersects the wt axis to the natural switching point (Fig. 2), the thyristors of one arm of rectifier 1 are turned on and the load current flows in phases B and C through the primary windings of the current transformers 4 and 5. At the same time, the emitting diodes of the respective optocouplers are turned on and, consequently, the corresponding photodiodes of the optocouplers are opened. A positive potential is applied to the bases of transistors 8 and 11 via control circuits 16 and 17. The transistor 8 is opened, the transistor 11 is closed. Phase L and load 14 current flows,.

In the interval from the natural switching point to the time when the voltage UE crosses the axis q and the t-current of load 2 flows through phases A and B through the primary windings of the current transformers 3 and 5. At the same time, the emitting diodes of the respective optocouplers are turned on and the corresponding photodiodes of the optocouplers are opened. A positive potential is applied to the bases of transistors 10 and 13 through control circuits 20 and 21. A transistor 10 will open. Phase C and load 14 are flowing i ± „

Similarly, the control of transistors 9-12 and the formation of a load current of 15 idt are provided. Therefore, phases A, B, C operate for the entire period, i.e. the converter consumes the sine-wave currents i, i- from the network ,; , il (J

This mode of operation has places irrespective of the magnitude of the thyristor control angle Ј (Fig. 2),

Thus, the proposed converter does not have a distorting effect on the network voltage of a limited power, i.e. possesses

improved power factor compared to the known. In addition, it is characterized by great functionality, since two

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Q 5

0

0

0

five

Additional single-ended transistor rectifiers are two additional DC sources, the average value of the rectified voltage at the outputs of which at a network voltage of 380/220 V and a (0 is 28 V. With increasing control angle .4 it is obvious that the output voltage of these sources will increase. To stabilize it, it is advisable to use parallel compensatory continuous stabilizers that can ensure the normal operation of the network rectifier in the absence of loads 14 and 15 (Fig. 1).

Claims (1)

Invention Formula t An ac voltage converter in nocTofHHoej containing a three-phase bridge rectifier on controllable valves with input terminals for connecting to the mains phases and output terminals for connecting 1 load, characterized in that, in order to expand the functionality and improve the power factor, two single-ended a rectifier on opposite-pole transistors, control circuits and three current transformers, the specified rectifiers are connected to each phase input terminal, and the outputs through All the loads are connected to the zero input terminal, and the base of each transistor is connected to the corresponding phase input terminal through a control circuit consisting of series-connected basic resistance and two parallel chains of two series-connected and according to photo-diode optocouplers, the emitting diodes of which, together with the emitting diodes the optocoupler of the control circuit connected to the other input phase output, form a series connection connected to the secondary circuit of the current transformer in connected between the third phase input output and the corresponding input output of the specified rectifier, and in parallel to the counter emitting diodes a series connection of the emitting diodes of the optocouplers of the corresponding control circuits of the reverse transistors Ti i is connected. about 9 fe-sh  I I n1 and 1 U I h about Ix And 4i and M J IKU1MI IF . ... and .and.   cgn it (4 Zg 00 Sf S , .i, .i. .and, 04  Ml IMJ 1M . and and N W- 9lS € fSl and  i  W I Mli mi ri IT i i i i j i j i Ft N -y ch i, kz im oi sign I about i i Hth III ill #T  . I gr. II - ( Lz L.X, im Ft N -y ch at cot  cut tH I ill #T - (- cut l-vt (pus.2