SU1744777A1 - Three-phase frequency multiplier - Google Patents

Description

In this case, the bias winding is eliminated, and the transformer core is made in the form of a three-phase magnetically connected magnet core of the core type.

FIG. 1 is a schematic diagram of a frequency multiplier; in fig. 2 - variation of the phase and line voltage curves induced in the transformer windings at different thyristor switching angles and provided that there is no self-induction EMF and the converter operates without load; in fig. 3 — oscillograms of voltage curves on one of the windings of the multiplier at different thyristor switching angles and operating on an inductive load.

A three-phase frequency multiplier (Fig. 1) consists of a transformer core 1, made in the form of a three-phase magnetically coupled core-type magnetic core with primary windings 2-13 and secondary windings 14-16, thyristors 17-28 wound on its terminals, which are controlled from phase shifter (not shown)

The frequency multiplier works as follows.

Consider the work of the first group of windings 2-7. connected through thyristors 17-22 according to the star circuit to three-phase shogi. At time ti (Fig. 2), the supply of the control pulse turns on the thyristor 17 and a current begins to flow through the primary winding 2 of phase A. At the ends of the terminals of the windings of phase A, EMF is induced, and since the magnetic conductor is magnetically coupled and has a symmetrical system, then the windings of phase B and C will also induce an emf of two times smaller and opposite in sign. At time t2, ts, respectively, the thyristors of phase 22 and phase 19 are switched on. The sequence of switching on the thyristors for this circuit is ...- 17-22 -19-18-21 -20- ...

FIG. Figure 2 shows the voltage curves at the input of the multiplier (a) the variation of the phase voltage curves induced in the windings of the transformer when the listed thyristors B are turned on. The times are ti 12 gz 14 t j-t6-. (B) at a larger control angle (c), as well as a change in the linear voltage curves for different thyristor switching angles (g e). For windings 8-13, included in the delta circuit, the sequence of their connection through the thyristors to the power source will be the same. The order of turning on the thyristors, respectively ...- 23 - 28 - 25 - 24 - 27 - 26 -... When operating three-phase

The multiplier of the multiplier mode simultaneously uses the primary circuits of the star circuit and the triangle circuit. The order of switching on the thyristors for phase A ...- 17-23-18-24 -... For phase B and phase C, the turning on of the thyristors is performed in the same sequence with a phase shift of control pulses, respectively, by 2/3 and 4 / 3 p.

On oscillograms of voltages one

of the windings of the multiplier of FIG. 3, one can follow the process of forming the resultant voltage of the quadruple frequency. Thyristor switching angle is

165 °, the EMF generated in each of the windings is not superimposed on each other, the resulting voltage curve is sharply non-sinusoidal. The turning-on angle of the thyristors is reduced and is 160 °; the emf of self-induction of the main phase is superimposed on the additional emf closest in phase. formed in a different phase, the resulting voltage curve is sharply non-sinusoidal, the oscillogram shows that

the amplitude of the additional emf is about half of the amplitude of the main emf. The switching angle is 155 °, both additional emf are superimposed on the emf of the main phase, the shape of the resulting voltage curve decreases slightly. Reducing the switching angle to 150 ° leads to a rather significant change in the shape of the resulting voltage curve, in which

the main output harmonic obviously predominates (the quadruple frequency), however, the content of higher harmonics is rather large, the curve is obviously asymmetrical about the x-axis. The switching angle is reduced to 145 °, the resulting voltage curve is close to sinusoidal, there are characteristic teeth in it, corresponding to the switching times of the thyristors. Firing angle reduced to

a limit value of 140 °. The resulting voltage curve varies smoothly, it is close to a sine wave and is almost symmetrical about the abscissa axis.

To obtain at the output of the doubled clock, windings 2-7 are used, connected through thyristors 17-22 according to the star to a three-phase network or windings 8-13, connected according to the triangle through thyristors 23-28.

Claims (1)

A three-phase frequency multiplier comprising a three-phase transformer, on each of three rods of which two pairs of primary windings connected to the network through the thyristors are located, and an output winding characterized in that, in order to simplify due to the failure of the demagnetizing circuit with the auxiliary power These rods are made magnetically interconnected in the form of a three-phase magnetic circuit. UA UB UB a one v v K K eight Tv / d $ Ј / g. 2 TP7 GL / b. / ATT A-f /