CS210004B1 - Connection for regukation of alterners in the paralell operation - Google Patents

Abstract

The wiring for inverter control in parallel operation consists of controllers and a compensating transformer. One alternating output of each inverter is connected to the corresponding equalizing current transformer windings. Its opposite pins are star-connected and connected to the load. On it are connected alternating alternators of inverters. Each inverter is connected to the output of separate voltage and current controllers, which are connected in parallel to the AC outputs of the corresponding inverters. Each inverter is equipped with an independent voltage and current regulator to ensure system redundancy. The equalizing current transformer provides for balancing the output currents of all inverters and minimizing equalization currents between the inverters.

Description

BACKGROUND OF THE INVENTION The present invention relates to a circuit for controlling inverters in parallel operation of a load consisting of controllers and a buffer transformer.

Regulece output voltage inverter operating in a redundant system must be such that, when failure of any of the inverters, or control b _ft loci, no violation of the function-enhancing left j * s třídače or inverter, which take the load or by impaired inverter. The wiring must ensure that each inverter is independently controlled, evenly distributed across the loads connected to the power supplies that do not have the same voltage across the output terminals.

The controller controlling the output voltage of the inverter receives the output voltage and current from the voltage sensor and from the current sensor to the load. However, if we interconnect two inverters to the load while ensuring frequency and phase matching, the inverter's output voltage does not correspond to the control signal from the controller, parasitic coupling occurs and the voltage at the common output oscillates around the set values. This is due to the fact that the inverter's internal resistances are close to zero and the small differences in source voltages cause uncontrolled equalization currents, which are manifested in the saturation of the winding elements in the inverters and eventual inverter failure.

Connections for controlling inverters in parallel operation using a common controller are known. With this connection, the inverter can achieve full current symmetry. However, the common feature of the two inverters in this circuit is the failure to meet the basic redundancy condition, since failure occurs, for example, in the event of failure to comply with the output voltage tolerance limits of one inverter.

Another known circuit for controlling inverters working in parallel is the so-called current lift used mainly in the control of rectifier units, in which one of the regulators operates as a control unit, while the other operates only in the current regulation mode.

Even this connection does not meet the redundancy requirement.

Claims (1)

SUBJECT Wiring for inverter control in parallel operate? a load consisting of controllers and an equalizing transformer, characterized in that one alternating output of each inverter (11, 12, 13) is connected to the corresponding winding of the equalizing current transformer (3), whose opposite terminals are connected and connected to the load (4), on The above-mentioned drawbacks are substantially eliminated by the invention which consists in the fact that one AC output of each inverter is connected to the corresponding winding of the equalizing current transformer, whose opposite terminals are connected to a star and connected to a load. The second AC inverter terminals are connected to it. Each inverter is connected to the output of separate voltage and current regulators, which are connected in parallel to the AC outputs of the corresponding inverters. The circuit according to the invention is further described by way of example with reference to the drawing in which 11, 12, 13 indicates three inverters operating in a redundant system, connected in parallel to the load 4 by means of an equalizing current transformer 3. In each case, the same output pole of each of the inverters 11, 12, 13 is connected to one end of the winding of the equalizing current transformer 3 and the other ends of the winding are connected to each other and connected to one load terminal 4 while the other is connected to the other terminals inverters. A separate voltage and current regulator 21, 22, 23 is connected to the output of each inverter 11, 12, 13. Since each inverter is equipped with an independent voltage and current regulator, system redundancy is ensured. The equalization current transformer 3 provides equalization of the output currents of all inverters and minimizes the equalization currents between the inverters within a range of output voltage variations due to inaccurate adjustments, temperature instabilities of the control circuits, or various internal inverter resistances. The equalizing current transformer 3 operates in such a way that the current flowing through each of the windings generates a magnetic flux in the respective transformer column, which closes over the other columns and excites the remaining windings against the voltage. Current imbalance in the transformer coils, for example due to different voltage values at the inverter outputs or different differential resistances, results in counter-voltages compensating for current symmetry variations. The design of the buffer current transformer is not the essence of the invention, is for those skilled in the art and does not need further explanation. OF THE INVENTION whose second outlet is connected to the second alternating terminals of the inverters (11, 12, 13), wherein the input of each inverter (11, 12, 13) is connected to the output of separate voltage and current regulators (21, 22, 23). connected in parallel to the AC outputs of the corresponding inverters / 11, 12, 13/.