SU1094123A1 - Three-phase ac voltage-to-dc voltage converter - Google Patents

Abstract

) 1. THREE-PHASE ALTERNATING VOLTAGE CONVERTER. A ETHMED containing a three-phase transformer, the beginnings of the primary windings of which form input pins, twelve controllable valves, a three-phase current divider, a secondary winding connected to a three-phase unregulated bridge rectifier, characterized in that, in order to improve efficiency and improve the weight and size parameters, the windings the three-phase current divider is connected to the first triangle and is made with central taps, each of which is connected through a pair of counter-parallel-connected controlled gates to the split point of the two remaining windings of the current divider, and each primary winding of the transformer is made with a branch with a relative number of turns from beginning to branch, equal to, the other controlled valves form three pairs when they are connected in parallel and connected to the second triangle, with the ends and the taps of the primary windings are connected to the tops of the first or second triangle. i 2. The converter according to claim 1, characterized in that (L the secondary windings are connected in a star, the ends of the primary windings are connected to the vertices of the second triangle, and the outlets of the primary windings are the tops of the first triangle. J. The converter according to claim 1, which differs in that the secondary windings are connected in a triangle-i nickname, the ends of the primary windings are connected to the tops of the first triangle, and the outlets of the primary windings to the tops of the second triangle.

Description

The invention relates to converter technology and can be used in power supply systems with adjustable rectified voltage, where higher quality of output and input currents is required, and: controlled voltage from the primary side of the supply transformer.

Three-phase AC-to-DC converters are known, consisting of two or more three-phase valve blocks, the anodic voltages of which are shifted to obtain multi-pulse, for example, twelve-pulse rectified voltage and current supply l.

But such converters do not provide a multi-pulse, including twelve-pulse control of the output voltage from the primary side of the transformer.

AC / DC converters are known that contain a three-phase transformer, the primary windings of which, together with AC controlled keys. current, form a star connected to a three-phase power source, and the secondary windings are connected in a star and connected to an uncontrolled rectifier 1U1 bridge 2 ..

The disadvantage of the transducers is that they provide only the pole and: the pulse control of the rectified voltage.

The closest to the invention is a converter containing a three-phase transformer, the beginnings of the primary windings of which form the input terminals, twelve controlled valves connected to the ends and two taps of the windings of the three-phase current divider and the ends of the primary windings and secondary windings connected to the star and connected to three-phase / Iy uncontrollable bridge rectifier 3J, and a short distance. The converter is that when the converter is operated on the primary side of the transformer, three controls are simultaneously connected avl emyk valve that creates losses, reducing efficiency. Work, a three-phase divider of a current in. Kayysgdom interval of conductivity of gates leads to increase in its dimensions. The use of twelve controlled valves in the device also increases the size of the converter.

The aim of the invention is to increase the efficiency and improve the weight and size parameters.

This goal is achieved by the fact that in a three-phase South-to-constant voltage converter, a three-phase transformer, whose primary windings begin to form

input terminals, twelve controllable valves, a three-phase current divider, a secondary winding connected to a three-phase uncontrollable bridge rectifier, the windings of a three-phase current divider are connected to the first triangle and are made with central taps, each of which is connected through counter-parallel-connected controlled valves is connected to the common point of the two remaining windings of the current divider, and each of them is transient, the transformer winding is made with a tap with a relative number of turns from the beginning to the tap equal to -J3 / 2, o tal controllable valves form three pairs with their counter-parallel connection and connected in vtoroytreugolnik, the ends and the taps of the primary windings are connected to the tops of the first or second triangle.

The secondary windings are connected in a star, the ends of the primary windings are connected to the vertices of the second triangle, and the outlets of the primary windings - to the vertices of the first triangle.

In addition, the secondary windings are connected in a triangle, the ends of the primary windings are connected to the vertices of the first triangle, and the outlets of the primary windings are connected to the vertices of the second triangle.

FIG. .1 is a schematic diagram of a three-phase AC-to-constant voltage converter in the case of connecting secondary windings into a star; in fig. 2 - time diagrams of power supply voltage of one phase, power supply current of one phase with fully smoothed output current Ij and load voltage UH / as well as a table of switched on state of controlled gates, counter-parallel pairs KOTOprdx perform the function of two-directional controlled keys, and rectifier diodes.

A three-phase AC-to-DC converter from a three-phase transformer with primary windings 1-3. Connected to a three-phase network, and with secondary windings 4-6 connected in a star and connected to the AC terminals of a three-phase uncontrollable bridge rectifier. assembled on diodes 7-12 and connected to terminals 13 and 14. Three windings of a three-phase current divider 15 have central taps 16-18 and coe are connected to the first triangle, the vertices of which are connected to taps of 1921 primary windings ransformatora.

Through bidirectional controllable yuchi, made up of counter-parallel pairs of controllable gates 22-27, for example, thyristors, each tap of the 16-18 windings of the current divider is connected to a common point of the two remaining windings of the current divider, and thereby with one of the tap of 1921 transformers . The three ends of the primary windings of the transformer are interconnected through three bidirectional controlled switches connected in the second triangle and made up of counter-parallel pairs of controlled valves 28-33. In the case of connecting the secondary windings of the transformer into a triangle, the ends of the primary windings are connected to the tops of the first triangle, the current of the splitter current, and the outlets of the primary windings are connected to the tops of the second triangular connection of two directional switches, consisting of anti-parallel pairs of controlled gates 28-33. The device works as follows. In the basic mode of operation, at any one time, one of the controlled gates 22-33 is in the on state. Controlled valves 22-33 are turned on with a certain sequence and in each power period each valve is in the on state for 30 al-degrees. In this case, when one of the voltage valves 22-27 on all the windings of the transformer is turned on, it is in phase or out of phase with one of the phase supply voltages. When one of the wires 28-33 is turned on, the voltages on the windings of the two phases of the transformer are in phase or out of phase with the corresponding linear supply voltage I. Thus, a suitable alternate switching on of the valves 22-33 allows the AC terminals to be formed a three-phase bridge rectifier on diodes 7-12 alternating voltages shifted by 30 eh. The connection of a three-phase current divider to the taps of the primary windings of the transformer ensures the equality of the amplitudes of these voltages. As a result, both the output rectified voltage U, and the supply currents 1d, ig, ij, are twelve type pulses. Regulation of the output voltage, as in the known phase control schemes, by changing the phase shift of the control valves being turned on with respect to the supply voltage. In this case, regulation is possible both with backward and with leading current. In the first case, the thyristors operate in the natural switching mode, in the second case, a coercion is required to switch to the thyristors or to use fully controllable keys of other types. Consider the operation interval when controlled valve 22 is turned on. In this case, the tap 19 of the primary winding of the transformer is connected via tap 22 to the central tap 16 of the current divider, with the beginning and end of this winding of the current divider connected to the tap 20 and 21 of the primary windings of the transformer. As a result, the phase current supply in tap 16 is divided into two parts, equal in magnitude and opposite to the phase currents i and 1 (,, i.e.; C (.) Denote the number of turns of the primary and secondary windings of the transformer, respectively VV, and W, and the number of turns of the section between the beginning and the removal of the primary winding through Vj. Neglect in analyzing the magnetizing current of the transformer, based on the equality of the magnetizing forces of the primary and secondary windings 1. 1. 10, 2.. Vv;. Sun Under the influence of secondary current transformer ia and with considering Diodes 8, 9 and 10 are conducted at the maximum interval. Load voltage at the output terminals, terminals 13, 14 b WT n-i The next interval of operation begins by turning on the controlled valve 32 and, respectively, turning off the valve 22. In this interval, through the switched on valve 32 the ends of the transformer primary windings in phases A and C are interconnected and the linear voltage Bds is distributed over them. The currents in phases A and C are equal in magnitude and opposite in direction. Accordingly, in this interval of operation, H cHavj Under the action of currents 1d and if, diodes 9. and 10 are conducted, and the load voltage UH U, C From expressions (4) and (.6) it also follows the required relative number of turns from the beginning to the outlet primary winding, equal to Чз72. Indeed, since in order to obtain a twelve-pulse mode of operation, the output voltage should be formed from shifted by 30 electrical degrees. alternating voltages with equal amplitude, and the amplitude of the linear supply voltage exceeds by a factor of 10 times the amplitude of the phase voltage of the supply, then the equality of the output voltages after 30 el. degrees based on (4) and (.6) .4. from where (7) 2 × 2 2 During the supply period, the controlled valves (thyristors) 22–33 are included In the sequence: 24-3127-28-22-32-25-30-26-29-23-23333333 and each interval change is accompanied by step change in phase currents d, 5, p. When one of the valves 22-27 is turned on in the primary currents, the steps of height N2 / W, and 3 Wj j-ZW; are formed, and when one of the valves 28-33 is turned on - steps with height Ij NWj and 0. Accordingly, the ratio of the height of the step . its primary current is 1: -11з7з: 1/2: 0, which ensures the elimination of higher harmonics below the 11th. FIG. 2 shows the current 1d. The currents ig and Ic have the same form, but they are shifted respectively by 120 and 240 el.grad. The shape of the output voltage Uji) FIG. 2 corresponds to the adjustment angle of 45 al. In the case of connecting the secondary windings of the transformer to a delta, the controlled valves 22-33 are turned on in the same sequence and the device operates in the same way, but at a given control angle, the output voltage decreases by a factor of. Thus, due to the operation in each interval of only one controlled valve, the efficiency of the device is increased, as compared with the known one. The three-phase current divider is involved in operation for only six intervals out of twelve, for the remaining six intervals the current divider between the phases is controlled valves 28-33. This allows to reduce the weight and dimensions of the current divider: its typical power is equal to 0.80 of the typical power of the current divider in the prototype. The converter requires a simpler control system, since the control of one valve does not require the multiplication angle of control signals required in the control circuit of a known device. A reduction in mass and size parameters is also achieved in the device due to the possibility of using bidirectional triac keys as controllable gates.

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Sequence of switching on the valve 7- / g and IZ-33

1

Claims (3)

(57.) 1. THREE-PHASE CONVERTER OF AC VOLTAGE IN PERMANENT. CLEAN, containing a three-phase transformer, the beginnings of the primary windings of which form input terminals, twelve controlled valves, a three-phase current divider, a secondary winding connected to a three-phase uncontrolled bridge rectifier, characterized in that, in order to increase efficiency and improve> overall dimensions, windings of a three-phase divider current are connected into the first triangle and are made with central outlets, each of which is connected to a common by the other two windings of the current divider, and each primary winding of the transformer is made with a tap with a relative number of turns from the beginning to the tap, equal to -4 × 72, the remaining controlled valves form three pairs when they are turned on and parallel and connected to the second triangle, while the ends and tap primary windings connected to the vertices of the first or second triangle. 2. The converter according to π. 1, § characterized in that the secondary windings are connected to a star, the ends of the primary windings are connected to the vertices of the second triangle, and the tap of the primary windings is connected to the vertices of the first triangle. 3. The converter according to π. 1, characterized in that the secondary windings are connected in a triangular angle, the ends of the primary windings are connected to the vertices of the first triangle, and the tap of the primary windings · is connected to the vertices of the second triangle.