SU657550A1 - Dc-to-three-phase ac voltage converter for frequency-controlled electric drive - Google Patents

Description

the coil, the beginnings of two of which, belonging to carved transformers, are attached to the inputs of the first diode bridge, and the ends of the 8TVC windings are connected to codes; the second diode bridge, and the outputs of the diode bridges shuntira. The key elements, the control of the seam, the inputs are connected to the secondary generator with a different frequency generator, and the output terminals of the converter are formed by common points of the secondary windings of the transio. formatters.

The disadvantages of such a converter include the complexity of its power section due to the use of three output transformers.

The aim of the invention is to simplify the converter and improve its energy performance.

The goal is achieved by the fact that in a DC to three-phase converter for a frequency-controlled electric drive two other secondary windings are located on the core of another transformer, the third secondary winding is connected to the third input of the first diode bridge with its end, k to the third input of the second diode The bridge is the beginning, aupou chickpea cell is filled in as a two-phase inverter.

FIG. Figure 1 shows a print scheme of the proposed converter with an intermediate high-frequency inverting link, made in the form of two single-phase inverters (a) and in the form of a three-phase bridge inverter (b), the key element control algorithm of which provides a linear shift of 90 linear. hail. FIG. 2 - timing diagrams, the most recent work of the converter (according to the scheme of Fig. 1a); in fig. 3 timing diagrams, according to the principle of operation of a rebel (according to the scheme of Fig. 1b).

The proposed transistor converter contains an intermediate high-frequency inverting element 1, output; None in the form of two single-phase inverters 2, 3 (({wg. 1a). The control inputs of the key elements of the inverters are connected to the output of the oscillator 4 at the frequency 11. secondary windings 9-11 of which are connected to the input terminals of two diode bridges 12, 13. Moreover, windings 9, 10 and 11 are connected to the input voltages of diode bridges

opposite ends. For example, the windings 10, 11 are connected to the input waters 14 ″ -16 of the diode bridge 13 with their beginnings, and the winding 9 to the output 15 by the end. At the outputs of these diode bridges, magneto-transistor elements with current feedback are included. The primary windings of current transformer 19 are connected in series with emitte1-collector junctions of power transistors 17, 18, the secondary windings of which are connected to control junctions of power transistors through auxiliary transioopbi 20, 21. The control & ny inputs 22, 23 of said auxiliary transistors are connected to a master oscillator 24 of frequency i. Midpoints 25, 26, 27 of the secondary windings of transformers 5, 6 form a three-phase converter output. As mentioned above, the inverting link 1 can also be made in the form of a three-phase bridge inverter (Fig. 1b) on transistors 28-33, the output terminals of which are connected to the main windings of transformers (Fig. 1b).

The formation of the output voltages of the converter is illustrated by the timing diagrams. FIG. 2 shows diagrams for the operation of the converter in FIG. 1a It presents:

 - voltage form on hanks 9, 10, 11 of transformers 5, 6 with frequency i (input 1 1 /);

  control signals applied to the inputs of the auxiliary transistors 20, 21 with a frequency f. d- (period

VliJ.

 ° P output phase voltage converter for each phase. & 1 frequency of the main harmonic f 2 1 fj-IM / (period (Т 1 / f 2).

FIG. 3 shows diagrams explaining the operation of the converter of FIG. 16. It presents:

Uj.g-TTjj - control signals that are fed to the inputs of inverters 28-33 transistors;

 The voltages obtained in this case on the windings of transformers 5, 6;

 control supplied to the inputs of the auxiliary transistors 2O, 21;

26 27 forms of output phase voltages for each phase of transforming bodies, the main harmonic frequency f,

Claims (1)

l i-iM /. 565 Entry angle 2 1, -1 equal to 60 el. hail., in voltages on windings of transformers 5, 6 (see fig. 2, h). It allows eliminating harmonics of multiples of 3 from the spectrum of output voltages of frequency ij, thereby improving the quality of output voltages and current of the converter. Regulation of the output voltage can be carried out in a high-frequency inverting link in two different ways. In the case when the consumer of electricity is not critical to the circulation of the above-mentioned harmonics of multiples of 3, from the voltage spectrum of frequency t, the regulation is made by changing the angle of control of the oscillator ,. The use of appropriate switching algorithms for key elements of the inverting link eliminates these harmonics and, at the same time, performs regulation, however, the number of switches of the inverting link increases, and the energy performance of the converter deteriorates. Compared with the known transform of the waves, the intermediate inverting variable, but whose high frequencies; made in the form of three single-phase inverters and three transformers, the proposed converter has one inverter circuit and one less-phase transformer. This simplifies the device. With the implementation of an intermediate high-frequency link in the form of a three-phase bridge inverter, instead of a three-phase transformer, two single-phase transformers are included, which also simplifies the converter and makes it more technologically advanced (HARDWARE at ten-ten-kHz frequency meets much more technological trueness than toroidal single-phase trannoformatrr). Since the intermediate high-frequency transmittance traversors operate at frequencies about an order of magnitude higher than the maximum output frequency of the npeo6pai 0 receiver and independent of it when controlling this frequency (fj), the latter has a reduced mass and size. In addition, transducer provides improved output current quality. The converter can be applied in all cases where conversion of a constant voltage is required, from one level to three-phase voltage of another level specified fixed or adjustable frequency from Hz to HI units with simultaneous regulation of Hairi. The formula of the invention of a DC / DC converter to a three-phase AC power frequency converter, comprising, a control unit, a high-frequency inverter cell of the same frequency with output transformers, one of the three secondary windings located on the heart of one of which which belong to different transformers, are connected to the inputs of the first diode bridge, and the ends of the same windings are connected; to the inputs of the second diode bridge, where the outputs / diode bridges are bounded by key elements, the control inputs of which are connected to a master oscillator of a different frequency, and the output terminals of the converter are formed by the middle points of the secondary windings of the transformers, so that simplifying and improving energy performance; two other secondary coils are located on the core of another transformer, one third; The btorp winding is connected to the third input of the first diode bridge with its end, to the third input of the second diode bridge, with the beginning, and the cell is made as a two-phase inverter. fa T, n p n n U lj lj u and, 23 one yt Fbi 25 26 ... f fkD :} ytJt D: -one “B