SU909775A1 - Static converter - Google Patents

Description

(5) STATIC CONVERTER

I

The invention relates to electrical engineering, in particular to power converters of energy, and can be used in static converters of direct voltage to alternating, galvanically developed, with an approximately sinusoidal form.

A known static generator contains two or more power converter cells, which are made in a bridge circuit on controlled keys, the outputs of which are connected in series. In each of the cells, one key pair commutes according to a purely rectangular law, and the second key pair has additional commutations located symmetrically with the main one. the output voltage of this cell is also single stage and J.

The output voltage of such a converter has an improved form with an increased number of stages, but its disadvantage is the complication

circuits associated with an increase in the number of converter cells.

The closest to the present invention is a static converter containing a power converter cell, made by a bridge circuit on controlled keys, for example, transistors shunted by return diodes, and a power transformer, the primary winding of which

10 is included in the AC diagonal of the specified cell .2.

The disadvantage of such an inverter is the poor quality of the shape of the output voltage having a single-stage

tS form and pause at zero level.

The circuit of the invention is an improvement in the quality of the output voltage form.

The goal is achieved by the fact that in a static converter,

Claims (1)

1U containing the output transformer, the first pair of controllable keys connecting the first output of the primary winding of this transformer with the input terminals, and the second pair of controllable keys associated with the second output of the specified winding and input terminals of the converter, all the keys bypassing the return diodes in series with each key of the second pair, a capacitor is introduced in parallel to which the additional winding of the output transformer is connected through the rectifier, and between these capacitors the third ondensor. FIG. 1 shows an electrical circuit of the converter; FIG. 2 switching diagrams of transistors and voltage diagram Ua on the windings of the output transformer. The electrical circuit of the converter contains key transistors 1-, the power circuits of which are shunted by return diodes 58, the output transformer 9 is connected to the load diagonal 10, additional windings 11 and 12 of the output trans (| yurmator, which are rectified 13-16 in parallel to the first and the second capacitors 17 and 18, connected in series with the switch 3 and 4, the third capacitor 19 is connected between the capacitors 17 and 18. The output voltage U (Fig. 2) has a two-stage form. but the open state of the transistors 2 and when the primary winding of the transformer 9 is applied voltage between the plates of the capacitor 1 and the reduced load current closes on the circuit: the positive input terminal of the inverter, the transistor 2, the primary winding of the transformer 9. diode 7 and then branch out on two branches: the first is the capacitor 17 positive input terminal, the second through the series-connected capacitors 18 and 19 to the negative input terminal. A large level, the output voltage of the same sign (positive) corresponds to a simultaneously open state of transistors 2 and 3, when the total voltage of two series-connected capacitors 17 and 19 is applied to the primary winding of transformer 9, and the reduced load current is connected through the circuit : positive input terminal, transistor 2, the primary winding of the transformer 9, transistor 3, and then branch off along two circuits: one through the capacitor 18 into the negative input terminal, the other through two series-connected capacitors 17 and 19 to the positive input terminal. The magnitude of this higher output voltage level is equal to the sum of the voltages on two series-connected capacitors 17 and 191 The inverter works in a similar way, generating negative output voltage levels, the amplitudes of which correspond to the simultaneous open state of transistors 1 and 3 or 1 and are equal to the capacitor 18 or the sum of the voltages on the capacitors 19 and 18. The windings 11 and 12 with diodes 13-16 serve to charge the capacitors 17 and 18 during the formation of a higher level of output filler, while maintaining the voltage plates in their predetermined limits. These windings are made the same so that a lower level of output voltage of positive polarity, equal to the voltage on capacitor 1, is the same in absolute value with the corresponding voltage of negative polarity (on capacitor 18). At optimal angles of additional switching of the transistors 3 and,. equal to kS, 135, 225 and el. degrees, and the ratio of the number of turns of the additional winding to the number of turns of the primary winding of the output transformer, the third and fifth harmonic components are missing in the voltage spectrum U, i.e. the quality of the form is significantly improved compared to the known one, in which, with the exclusion of the third harmonic component, the ratio of the fifth harmonic component to the first is 20%: Thus, the invention allows to significantly improve the quality of the output voltage form by simpler means. The invention is a static converter containing an output transformer,