SU557460A1 - Multiphase controlled rectifier - Google Patents

Description

(54) MULTI-PHASE CONTROLLED RECTIFIER

one

The invention relates to the field of electrical engineering and can be used to control electrical installations, which require long-term deep control of a constant voltage, for example, to control direct-current drives.

A two-bridge rectifier is known to be partially controlled, in which by parallel connection through an equalization reactor of two bridges connected to two stars of the transformer secondary windings, it is possible to slightly increase the power factor, eliminate triple frequency pulsations and eliminate even harmonics in the primary current.

However, an increase in power efficiency and a decrease in voltage ripple on the load are not so significant.

The purpose of the invention is to increase the power factor and reduce the ripple voltage on the grid.

The goal is achieved by the fact that between the zeros of the winding stars of the transfomator, an additional leveling reactor is turned on, the average output of which is connected to the extreme points of the equalization through two separating valves

reactor bridges. In this case, only bridges valves directly connected to a surge reactor, or only bridges valves, or all valves can be controlled.

FIG. I shows a diagram of the proposed supra miter with symmetric control; in fig. 2 shows diagrams explaining the operation of the top-view circuit for the case when only valves directly connected to the reactor are made controlled.

The multiphase controlled expander contains valves 1–6 and valves 7–12, two return stars 13, 14, the primary winding 15 of the transformer, load 16, valves 17.18, equalization reactors 19 and 20.

The following notation is used in the diagram:

a) network voltage

b) the voltage between the zero star 14 and the anodes of the valves 7-12,

c) the voltage between the anodes of the valves 17, 18 and the aiodes of the valves 7-12,

d) voltage at the surge reactor 20,

e) the voltage between the cathodes of the valves 4-6 and the anodes of the valves 7-12,

g) load voltage 16,

g) voltage at the equilibrium reactor 19,

h) the current through the valve 18, and) the current through the valve 5,

k) the current of the zero wire of the star 14 (the same for the star 13),

l) the current through the valve 7,

m) dermal current phase A.

The proposed three-phase rectifier consists of two three-phase valve bridges connected in parallel through the fusion reactor 19 on valves 1–12. The valve bridges are connected to two reverse stars of the secondary windings 13, 14 of the transformer with primary winding 15, made according to the star-triangle scheme. Between the zeros of the stars of the windings 13, 14 of the transformer, an additional leveling reactor 20 is switched on, the converting output of which is connected to the extreme ends of the equalization reactor 19 of the bridges through two separation valves 17, 18. The load 16 of the rectifier is connected between the average output of the surge reactor 19 and the anode of the valves 7 - 12.

The circuit will work without any violations while simultaneously switching all the valves to the opposite direction of the current (i.e. when changing the location of the anodes and cathodes).

When the required voltage control range is 50–100% of nominal and recovery is not required, only valves 1–6 are actuated. When the required voltage control range, O, is 100% and the recovery is carried out to counter-em. with. the inverter up to 50% of the rated voltage, the valves are controlled 1 - G2. When the required range of regulated voltage O is 100% and recovery is carried out on counter-emf. up to 100% of the nominal voltage {and, controlled, all valves 1–12, 17, 18 are executed. For the nominal load, the load is received when the valves 1–12 are fully turned on (voltage of the uncontrolled bridge circuit).

The operation of the circuit, when controlled (thyristors) are performed only on gates 1-6, and osgals are diodes, with symmetric control 1O1 and gates 1-6, as shown by the diagrams (Fig. 2). The load voltage 16 lies somewhere in the range of 50-100% of nominal. Valves 7-12, windings 13, 14, and a balancing reactor 20 form a rectifier circuit of two reverse stars with a balancing reactor. Equalizing reactor 20 ensures the simultaneous operation of two zero rectifying circuits (in Fig. 2c, the voltage at the output of this rectifying circuit is shown) and the simultaneous and equal consumption of currents from the zeros of the windings 13, 14 (Fig. 2k). If for some period of time the valves 1-6 are simultaneously disconnected, then the voltage of the rectifier circuit of two reverse stars with a balancing reactor is applied to the load 16. In this mode, the current of the average output of the reactor 20 is exactly divided by.

lam between gates 17,18 thanks to equalizing reactor 19. At that time, no voltage was applied to equalization reactor 19 (the difference between the first and the same voltage drops of the valves 17, 5 18 — that is, the fraction of a volt) —for the diagram (FIG. 2g) the time intervals are absent for the voltage on the reactor 19. When switching on any valve 4-6 between: the channels of the valves 4-6 and the anodes of the valves 7-12 (Fig. 2e), the voltage of the bridge circuit appears higher, and valve 18 is closed. If at this time all valves 1-3 are disconnected, then between the cathodes of the valves 1-3 and the anodes of the valves 7-12 there is a voltage applied to the output circuit of two reverse stars with a balancing reactor. With a large sequential inductance in the load circuit 16, the current through the load does not change. Thanks to reactor 19, this current is exactly halved and, accordingly, half of the current is consumed from

0 of the bridge circuit, half of the two reverse star circuit with a balancing reactor. Since before switching on any of the valves 4-6, the two reverse stars gave the entire load current, after switching on any of the valves 4-6

5 twin-star returns only half the current. These variations in the zero point current of stars 13, 14 are clearly visible in the diagram of FIG. 2k The unbalance voltage of different rectifying circuits is applied to the choke 19 (Fig. 2g). Obtained by

In this case, the load voltage (Fig. 2e) has a pulsation amplitude of six times the frequency (moreover, due to the reactor 19, these pulsations are 2 times less than if the circuit simply switched the load from the circuit level two

5, the return stars with an equalizing reactor on the pavement), and the current (Fig. 2m) has an amplitude smaller than the amplitude of the load current, a shape sufficiently close to a sine wave and a slight shift. The circuit does not cause a forced flow.

There is a transformer magnetisation, and in the primary current there are no even harmonics.

With asymmetrical control, the circuit allows for an even greater increase in power factor, however, in the primary current

5 even harmonics appear and the secondary windings 13, 14 are to be designed according to the scheme two identical zigzags. Even harmonics with asymmetric control can be eliminated by the parallel operation of another asymmetric one.

over the top of the transformer or with a secondary transformer with four secondary windings.

The effect obtained in the circuit is achieved by switching the load from one circuit to another and by providing equalization reactors with simultaneous operation of different rectifier circuits.

Claims (4)

Invention Formula Q1. A multiphase controlled expander containing two multi-phase bridges connected in parallel through an equalization reactor, connected to two stars of transformer secondary windings, zero points of which are connected through an additional equalization reactor, q, different in order to increase the power factor and reduce output pulsations voltage, the average output of the additional reactor through two separation valves is connected to the extreme terminals of the bridge-leveling reactor. 2. The actuator according to claim 1, characterized in that it is performed on controllable valves. 3. The actuator according to claim 1, characterized in that the bridges on the controllable valves are filled. 4. The expander according to claim 1, characterized in that only the bridges that are connected directly to the equalization reactor are executed on the controlled valves.