SU964912A1 - Three-phase ac voltage-to-dc voltage converter - Google Patents

Description

(5) THREE PHASE ALTERNATING VOLTAGE CONVERTER TO PERMANENT

one

The invention relates to power converter technology and can be used in the design of secondary power sources for electrical and electronic equipment, for various purposes.

AC / DC converters are known that contain two single-phase transformers and a three-phase bridge rectifier. Each transformer is made with one primary and one secondary windings. Some of the primary windings of transformers are interconnected and their common point together with other free leads of these windings form leads for connecting the three phases of the power supply, and the common point of the secondary windings connected in series and their loose leads serve for connecting the input of a three-phase bridge rectifier GT.

The disadvantages of the known devices are the impossibility of their use in single-point mid-point rectifiers due to the absence of a symmetric multi-phase voltage system relative to the common (middle) point, as well as the inexpediency of their use in rectifiers designed for low output voltage and more. load current, since bridge rectifiers have large volumes of diodes with heat sinks

10 and mass.

Closest to the invention is a variable voltage adjustable voltage constant-to-current converter containing two single-phase transformers with a primary and a secondary with a middle point windings, the primary windings of which are sequentially interconnected to each other and through a voltage regulator connected to one of the supply phases

Claims (1)

20 of the network, and the other two phases of the mains are connected to the free terminals of the primary windings. The secondary windings together with the valves form two radial filters through their own filter choke C2. However, in the known device there is no symmetric multi-phase voltage system with respect to the midpoint, which degrades the output characteristics of the device. The purpose of the invention is to improve the output characteristics by obtaining a three-fold frequency of voltage pulsations at the output. This goal is achieved by the fact that in a three-phase AC / DC converter, with two single-phase transformers, the primary windings of which are connected in series, their connection point is connected to one of the three phases of the power supply, the free terminals are connected to two other phases supply network, one output of the main secondary windings are connected to the anodes of the main valves, an additional secondary winding is inserted into each single-phase transformer, and both of these windings are connected to each other edovatelno one free end being connected to the anode further inputted gate, whose cathode with the cathodes s.oed nen main valves of Rasun first output terminal and second output terminal formed by the other main terminals of the secondary windings and the other terminal of series-connected additional secondary windings. FIG. 1 is a circuit diagram of a converter; in fig. 2 is a vector diagram of load stress. The converter contains two single phase transformers 1 and 2 with the primary windings 3 and connected in series and connected to the power supply networks A, B, C of the mains, the main secondary windings 5 and 6 are connected to the anodes of the main valves 7 and 8, as well as between each other in series and with the output of additional secondary windings 9 and 10, connected in series according to another output connected to the additional input valve 11. The output terminals for connecting the load 12 are formed by the combined cathodes of the valves and union of basic and additional secondary windings. at once. When the primary windings ZIL of single-phase transformers 1 and 2 are connected to a three-phase mains supply, the main secondary windings 5 and 6 and additional secondary windings 9 and 10 form voltages whose vectors Ua and (Jc are shifted relative to each other by 120 e. Degrees. Vectors voltages UQ and (Jf p, complete x. secondary windings 9 and 1 (K, add up and the resulting BeKropV t ecre with the voltage vectors Uo and the main secondary windings 5 and 6 form a symmetrical three-phase system of voltage vectors HQ, U, Uc shifted relative to each other by 1 20 el. Degrees, as shown in the vector diagram (above (fig.). Voltages (JQ and -Uc are rectified by valves 7, 8 and 11, and a constant voltage with a three-fold voltage is formed at load 12 ripple frequency over the period of the frequency of the supply voltage. Obtaining a symmetrical three-phase voltage system leads to an improvement in the output characteristics of the described device. Formula of Invention and their connections are connected to one of the three phases of the power supply network, free terminals are connected to two other phases of the power supply network, one terminals of the main secondary "windings are connected to the anodes of the main valves, in order to improve the output characteristics each single-phase transformer cc, secondary additional winding, and both windings are connected in series with each other, one free output is connected to the anode of an additionally inserted valve, the cathode of which is connected to the cathodes of the main ventilation the first output pin, and the second output pin is used by other outputs of the main secondary windings and other outputs