SU765980A1 - Method of shaping staircase sinusoid-approximating inverter output voltage - Google Patents

Description

I

The invention relates to electrical engineering, namely to inverters with a stepwise approximated sinusoidal form of the output voltage, and can be used in secondary power sources of automation and electric drive systems.

There is a known method of forming a step voltage by dividing the inverter into two identical converter cells operating at the main frequency, the output voltages of which are phase-shifted and summed in load circuit 1.

The disadvantage of this method is that the output transformers of both cells operate at the fundamental frequency and therefore have increased dimensions.

The closest technical solution to the present invention is a method of forming a stepwise approximating sinusoid voltage of an inverter containing a main converter cell, at the output of which a square voltage of the fundamental frequency is formed, and an additional converter cell, at the output of which a square frequency signal of higher frequency, multiple primary and summarize them with C23.

The disadvantage of this known method is the low quality of the output voltage form.

The purpose of the invention is to improve the shape of the output voltage by increasing the number of its steps.

This is achieved by the fact that

10 of the indicated frequencies are taken in different 2, where I, such an integer, in the output voltage of the main converter cell at each transition through the zero level form a pause symmetrically relative to the half-period boundary, and the output voltage of the additional cell is shifted in phase relative to the output voltage the main cell at an angle of 20 45 / pell. hail, on the main frequency.

At the same time, when and 1 in the output voltage of the main cell, the specified pause is formed with a duration of 30 el.

25, in the output voltage of the additional cell, at h s 1, at each transition through the zero level, a pause is formed; the duration is h 30 e. hail, on the main frequency, and also when h- 1 in

Claims (2)

The 30 output voltage of the main cell is formed by a pause of duration 9O / and el. hail, on the main frequency. FIG. 1 shows a block diagram and voltage diagrams of a single phase inverter; in fig. 2 is a block diagram and diagrams of three-phase inverter voltages. The inverter (Fig. Id) contains the main 1 and additional 2 converter cells. Cell 1, and in some cases cell 2, is performed according to a scheme that provides a pause at the zero level of the output voltage. The output voltage Od of cell 2 with a frequency of twice (Fig. Id, c) or vchet probably (Fig. 1d) higher than the fundamental frequency of the inverter is summed up using output transformer 3 cell 2 with the supply voltage UB of the inverter, and the supercharger voltage Ubjk + IJA It is used to power the main cell 1, the keys of which are clogged on the main frequency with a shift of 22.5 al. (Fig. 1G) or with a shift of 45 e. hail, at the fundamental frequency (Fig. 1 (5, в) and so that, apart from the usual inversion of voltage 6 JA), at the beginning and at the end of each half-cycle of the fundamental frequency, a pause at zero level with duration, HanpiiMep, 30 el. (Fig. 16, 6) and 45 e. degrees (Fig. 1d). The cell keys are controlled by signals from the control unit 4. The three-phase inverter (Fig. 2a) has three main converter cells 1, 5, 6, conclusions which are connected by a star, and one common additional cell 2 with an output transformer 3, the secondary winding It is connected in series to the power supply circuit of the main cells, and the frequency of the output voltage Od of cell 2 is six times higher than the output frequency of the inverter. The sum of voltages Ue + Od is inverted by cells 1, 5, 6 so that the output voltages of these cells have pause at the zero level of 30 e.h.d.d.circuit .sdvir on.phase 120.degree, and phase shift relative to the voltage of Od cell 2 by 15 e.d.These output voltages have the form of rectangles with two protrusions on top ( FIG. 2 ($), and the linear output voltage Udr, equal to the difference of the voltages and UB, has a three-step form. Thus, in the proposed method / with a given number of converter cells, the shape of the inverter output voltage is more close to a sine wave, since it has a greater number of stages. Claim 1. Method of forming a stepwise approximating sinusoidal output voltage of an inverter containing a main converter cell, the output of which forms a fundamental voltage of the fundamental frequency and an additional converter cell, the output of which generates a voltage of higher frequency, a multiple of the fundamental, and summ1 them, characterized in that, in order to improve the shape of the output voltage by increasing the number of its steps, the multiplicity of these frequencies is taken hydrochloric 2h, where h - any integer a. the output voltage of the main converter cell at each transition through the zero level forms a pause symmetrically with respect to the half-cycle boundary, and the output voltage of the additional cell is shifted in phase relative to the output voltage of the main cell by an angle of 45 / I el. hail, on the main frequency. 2. Method according to Claim 1, which means that, with Claim 1, the indicated pause in the output voltage of the main cell is 30 e. degrees 3. Method POP.2, I differ by the fact that in the output voltage of the additional cell with each transition Through a zero level a pause of 30 zl is formed. degrees on the basis frequency. 4. A method according to claim 1, characterized in that, at AND i: 1, said pause in the output voltage of the main cell is 90 / and electric. degrees on the main frequency. Sources of information taken into account during the examination 1. USSR author's certificate number 124517, cl. H 02 M 7/537, 1959. 2. US patent 3002142, cl. 321-9, 1961 (prototype). GM iirti ex : ± and" a) fug./l n-. one one five at W. Tj Det U) .tiei-te t /: U AND L TJTJTJTjrTJbTLT