Method and apparatus for supplying voltage to a three-phase voltage system having a load-carrying neutral conductor with a pulse width modulated three phase invertor

US5091839A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Hartmut Gaul · Königsee, DE
• Albert Mueller · Aschaffenburg, DE

Key dates

• Filing date: Sep 21, 1990
• Grant date: Feb 25, 1992
• Expiry date: Sep 21, 2010

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02E40/50
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

To maintain a defined three-phase voltage system at the output terminals of a transformer device TE, for example, a transformer in a delta/wye connection where the primary-side neutral point is unconnected, even when an asymmetrical load is connected to it and to the secondary-side neutral point, single-phase transformers are used, whose primary windings are supplied with voltage by a pulse-width modulated, three-phase invertor in a bridge connection. Through the use of voltage regulators, the actual values of the secondary-side line voltages form the control voltages for each bridge-arm pair. The closed-loop control circuits of the three phase voltages are broken down in accordance with the structure of the transformer device by means of a break-down element. The setpoint values can be calibrated to a synchronizing voltage, and/or a current control for the conductor currents is superposed on the voltage regulators.