SU860240A2 - Inverter with stepped shape of input voltage - Google Patents

Description

 The invention relates to converter equipment and can be used in power supply systems for radio electronics, automation and electric drive devices.

According to the main author. St. 699627 is known an inverter with a stepped output voltage, containing in each phase 2N bridge converter cells (where N is any integer), in the diagonal of which are main chokes with an average output winding, and in which N groups of additional chokes are inserted with an average output winding , the extreme conclusions of the chokes of the first group are connected with the average conclusions of the main throds of adjacent cells, the extreme conclusions of the chokes of each subsequent groups are connected with the average conclusions of the chokes of the previous group, and cf The single output of the throttles of the Nth group is connected to the output terminal of the inverse phase of the inverter;

A disadvantage of the known inverter is the need to complicate the circuit and significantly increase the weight in order to obtain a sufficient degree of phase voltage sine wave in the presence of zero output.

power source. For example, to obtain 5 steps in phase voltage, it is necessary to have 48 power switches and 21 chokes in the power circuit of a three-phase frequency converter. 96 power switches and 45 chokes are required to obtain 9 steps.

The purpose of the invention is the improvement of mass-dimensional parameters and the coefficient of non-linear distortion of phase voltage.

This goal is achieved by the fact that in the device each phase is additionally equipped with two successively connected key elements connected to a constant voltage source and a transformer, the primary winding of which is connected between the additional connection points

There are 20 key elements of this and the next phase, and the secondary winding is connected to a tap from the middle point of an additional throttle of this phase.

Claims (1)

FIG. 1 shows a diagram of a lagged inverter with a stepped form of the output voltage using B as the power switches of the transistors) in FIG. 2 - voltage diagrams at the main sections of the scheme. FIG. Figure 1 also shows a power supply providing a constant voltage on the converter power supply buses having a zero point output. Each of the inverter phases A, B, C is composed of four main and additional racks of key elements (transistors). For phase A, the main racks consist of transistors 1-8, and additional - from transistors 9 and 10. For phase B, the main racks consist of transistors 11-18, additional - 19 and 20. For phase C, the main racks consist of transistors 21-28, additional - 29 and 30 (Fig. 1). In the diagonal of each rack, chokes 31-36 are included, and the taps from the midpoint of the windings of these chokes are connected via half-windings of additional chokes 37-39. important racks of this and its neighbor phase. The ratio of the number of secondary turns to primary is assumed to be 0.075: 1. The transistor 1MI is controlled from the pulse distributor, having in its composition a divider by 15. In accordance with the curves of FIG. 2, a high-frequency voltage with an amplitude equal to with a fill factor of one. At the same time, the voltage on the winding of the additional wire has landed 37 is zero. The voltage between A (3 and power zero (Fig. 2) is zero. In the interval from 12 to 48, the high-frequency voltage 12 remains on the windings of chokes 31 and 32, but the filling factor becomes 0.5. At the same time a high-voltage voltage appears with an additional winding, with an amplitude equal to half the voltage. In the interval from 48 to 132 °, all the upper or correspondingly lower transistors of the main racks of the phase A are open. and 37 are equal to zero. Half of the Next, the processes are repeated in reverse order (Fig. 2). Simultaneously with the control of the main racks, the pulse distributor controls the transistors of the additional racks, so that the secondary windings of transformers 40 - 42 cause voltage (40 f +2 (Fig. 2). These facilities are algebraically collapsed with voltages miU QQ. As a result, a voltage UAO and its equivalent voltages UgQ f UCQ are obtained between the power zero and the outputs of the inverter, and a series of control signals of the last phase is equivalent to control signal for a phase A, but shifted by 120 Phase voltage has six steps and harmonic distortion not exceeding 8%. The linear voltage has eight steps and a non-linear distortion factor of about 7%. The frequency at which the throttles operate is determined by calculation, based on the frequency properties of the elements. Since each phase with a power zero forms a self-contained converter, the circuit can be used in various p-phase variants. In this inverter, on 30 power switches, 9 droplets and three transformers, it is possible to obtain six steps in the voltage between the zero output of the power supply and the phase with a non-linear distortion factor of phase voltage not exceeding 8%. Formula of Invention Inverter with a stepped form of output voltage according to the aut. St., No. 699b27, characterized in that, in order to improve the weight and dimensions and the nonlinear distortion factor of the phase voltage, each phase is additionally equipped with two series-connected key elements connected to a constant voltage source, and a transformer, the primary winding of which is connected between the points of connection of additional key elements of this and the next phase, and the secondary winding is connected with a tap from the midpoint of the additional throttle of this phase. Sources of information taken into account during the examination 1. USSR author's certificate I 699627, cl. H 02 M 7/515, 1972.