SU1415370A1 - Device for controlling a.c. voltage - Google Patents

Abstract

This invention relates to the field of power conversion technology. The purpose of the invention is to ensure the linearity of the adjustment characteristic, increase the efficiency and expand the scope of use by organizing a high-current output. The device contains a transformer 1 with a primary winding 2 and secondary windings 3-5, keys 6-11, connected in pairs between the terminals of the secondary windings 3-5. The terminals of the keys 7, 9, 11 form the terminals of the adjusting sections connected in parallel through the windings 13 located on the three-core closed magnetic circuit 14. A feature of the device operation is the phase shift between the control pulses of the keys related to the neighbor sections. tt-, ea by which the supplied circuit is achieved. 1 hp f-ly, 6 ill. with (L

Description

At i /, N I t / i

  Mr.JJ C

FST | /

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FIG.

one

This invention relates to the field of power conversion technology.

The purpose of the invention is to ensure the linearity of the regulating characteristic, efficiency and expansion of the field of use.

FIG. 1 shows a variant of the power part of the proposed device; in fig. 2 shows an embodiment of the control unit in FIG. 3 - timing diagrams explaining the operation of the device i in FIG. 4 - timing diagrams explaining the operation of the control unit i in FIG. 5; timing diagrams explaining the possibility of implementing in a device the properties of the frequency converter and the number of phases (from one in M 3); in fig. 6 - adjustment characteristics 1, f (ci), and U} (, j fCot), where,), U (5, V) is the relative voltage value of the first, third and fifth harmonics, respectively, for the main and auxiliary outputs (and ) f and the dependence of the magnitude of the distortion of the output current, measured by the harmonic current coefficient Kp,;., on the angle of control oi at different angles of phase shift Cpc according to the main harmonic of the RL-load (b); in fig. 7 is another variant of the power part of the device.

The power part of the device (Figs. 1 and 7) contains a transformer 1 with primary winding 2 with secondary windings 3-5 (the number of which, for definiteness, is subsequently taken to be 3). Between the outputs of each of the windings are included chains of series-connected keys 6–11 of the main and shunt keys. A set of keys 6-11 forms a switch 12. A secondary winding with a key chain forms an adjustment section. In the embodiment of FIG. 1 the outputs of the sections formed by the power terminals of the keys 7, 9 and 11 are connected through the windings 13 located on the M rods of the M-core closed magnetic wire 14 with the output voltages. The outputs of the additional M-phase winding 15 form additional output terminals, from which the M-phase voltage can be removed, the nearest harmonics in the spectrum of which are harmonics with multiplicity relative to the network frequency f

15370

(a-1) and (a + 1), where a -r is the ratio of 1

frequency switching key switch 12 to the frequency f, the network. In the FIG. 3 and 5 examples a 6.

The control unit (Fig.2) contains a control input 16, a frequency adjuster 17 with an output signal U- - (Fig.4), the first and second M-channel pulse distributors (RI) 18 and 19 according to a scaling circuit with paraphase outputs, clock inputs connected to the output of the frequency adjuster 17 directly and through controlled phase-shifting (FSC) 20, respectively. To enable one hundred percent adjustment of the output voltage of the FSA 20, it is implemented in the form of serially connected identical FSA 21-23, connected via control input 16. Each of the FSU 21-23, which is a controllable delay unit, provides in the limiting case the maximum -

Tm

hold for a time equal to ut

M

0

five

0

five

0

five

where 1 f is the regulation period, and the entire FSU 20 is M times larger (by JBrem, equal to T). The outputs a, a, b, b, c, c of the distributor 18 and the outputs a, a, b, b, c, of the distributor 19 are connected to the inputs of the M-channel logical node. Each of its channels 24-26 is made up of logic gates 2and 27 and 28, logic gamut 2ILI 29, and a logic circuit HE 30. From the outputs 31-36 of the control unit, signals are fed to the inputs of the corresponding keys 6-11,

The algorithmic characteristic of the power section, defined by the control unit, is explained by the diagrams in FIG. 3, where U ,, - U, are the signals at the outputs 31-36 of the control unit, respectively, supplied to the control inputs of the keys 6-11, respectively, and characterizing them condition. As a result of switching the keys according to the indicated algorithm, voltages U, uj and having the form of signals with pulse width control (WID) are formed at the outputs of the adjusting sections of the device. Roman numerals with signals indicate the section number when counting down from top to bottom.

When summing the voltages U, and and and the resulting output to

l

The strap is determined by

II II pg m g Ui + Uj). Stress

and (,, and Ujci which are applied to phases A1, B1, C1 of the winding 13 of a three-phase transformer, have the form shown in Fig. 3 (and in more detail in Fig. 5).

The operation of the control unit is illustrated in FIG. four.

Each of the FSU 21-23 can be performed according to any well-known scheme. Most often, the FSU is made in the form of a series-connected sawtooth voltage generator (GGTN) with voltage f (Fig. 4) and a comparator, whose control input is given a signal Un. As a result of the comparison, in the comparator, signals U | .f and U | j receive a signal Uji, the leading edge of which is lagging behind the input, clocking FSU signal U, by an angle about (figure 4).

RI 19 is triggered by the leading edge of these pulses and., As a result of which its output signals are shifted by an angle oi, with respect to the output signals of RI 18. The single-channel construction principle used in the control system allows for synchronous (symmetric in angle of rotation) regulation in all adjustment sections and 1ETIM, it is the most possible to realize the advantages of the control algorithm used.

To extend the functionality, the M-rod closed magnetic circuit 14 is provided with an additional M-phase winding 15, from which the M-phase voltage system is removed, and in the nearest harmonics in which are harmonics (in the example U, (5) and U (7 )) frequencies (al) f, f and (a + 1) f, having the same phase rotation order (Fig.5). Despite the not very high quality of this voltage (which can be improved by the filter), it can nevertheless be used directly, for example, to power asynchronous type (BP) motors installed in the ventilation cooling system of the same device. The increased frequency of supplying blood pressure, set by an appropriate choice of the parameter a, allows the implementation of

to incorporate a cooling system with improved mass-dimensional indicators. Adjustment characteristics

u (0). UMO f / «) and U, V, f, (oi) layer is the main one and for these two minor (which have become useful 1) harmonics in relative units are presented in FIG. 6a.

The change in the quality indicator, the output current for different angles of the RL-load (C), according to the main harmonic as a function of the control angle od, is shown in FIG. 6b.

As can be seen, the values of the angles o / 0 are 0.333, 0.566 and the regulation area is divided into three zones, moreover, at points oi о К p (.j 0. In contrast to the known solutions, in which the non-ideal characteristics used in the control unit of the element base during transitions from one control zone to another entails a jump in the regulation characteristic, in

the proposed solution, this characteristic is fundamentally strictly linear in nature (fig.ba).

0

five

0

five

0

five

Claims (1)

1. An alternating voltage control device comprising a transformer with primary and M number of secondary windings, between the terminals of each of which a chain H j of two main and shunt alternating current keys connected in series, forming together with the corresponding secondary winding an adjusting section, as well as a unit control, wherein the power outputs of the shunt keys form the outputs of the adjusting sections, which are interconnected according to a summation scheme, characterized in that, in order to ensure linearity of the adjustment characteristic, increasing the efficiency and expanding the area of use by organizing a high-current output while reducing the installed power, it is equipped with an M-rod closed magnetic circuit with windings of identical number of turns on its rods, one of the same polarity output outlets of the adjustment sections are combined among themselves, the image of the first output output of each of the other output outputs 1 & f 77 20 21  NI I L R J / FIG. 2 and, Usi Un% Uy, and and 3S  3g i / t tft (coy) out1 U "1 Fig.z Uf ruH 6 with about AT WITH ahh Ss a 8 with a 8 s jg jz 35 3S f1 / g. fit9.f 1) 1.0 0.8 0.6 0, 0.2 ABOUT % gi) 0.2 Q, t 0.6 0.8 1.0 O 0.2 0. 0.6 0.6 1.0 Rag. 6 GGI: H s1 eight th „. & 1. FIG. four one. and L