DC power transmission system of voltage source converter using pulse-interleaving auxiliary circuit

• US 7,499,291 B2
• Filed: 01/12/2007
• Issued: 03/03/2009
• Est. Priority Date: 07/06/2006
• Status: Expired due to Fees

• Current Assignee: Myongji University Industry and Academia Cooperation Foundation
• Original Assignee: Myongji University Industry and Academia Cooperation Foundation
• Inventors: Han, Byung Moon
• Primary Examiner(s): Han; Jessica
• Assistant Examiner(s): PHAM, EMILY P
• Application Number:
  US11/652,983
• Publication Number:
  US 20080007978A1
• Time in Patent Office: 781 Days
• Field of Search: 363/17, 363/35, 363/37, 363/98
• US Class Current: 363/17
• CPC Class Codes: H02M 7/19 arranged for operation in series, e.g. for voltage multiplication
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters
• CPC Class Codes: H02M 7/7575 for high voltage direct transmission link
• CPC Class Codes: Y02E 60/60 Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

A DC power transmission system of a voltage source converter using a pulse-interleaving auxiliary circuit is disclosed. The converter system comprises an IGBT converter for converting an AC power to a DC power or the DC power to the AC power; an open Y-Y transformer and a Y-Δ transformer for stepping up or stepping down the AC power having a predetermined magnitude; a capacitor for dividing a DC voltage; and a DC Auxiliary circuit composed of a normal transformer and half-bridge for overlapping a pulse type input voltage to increase the number of pulses of an output waveform. In using a DC auxiliary circuit composed of normal transformer and 3-level half-bridge to increase the number of pulses of the output waveform by superposing the voltage in the form of the pulse, a normal transformer may be used instead of the tapped transformer to reduce the size thereof and to obtain an accurate transformer ratio, and a 3-level half-bridge may be used instead of the H-bridge to reduce the switching loss.

Claims

1. A converter system comprising:

an IGBT converter for converting an AC power to a DC power or the DC power to the AC power;

an open Y-Y transformer and a Y-Δ

transformer for stepping up or stepping down the AC power having a predetermined magnitude;

a capacitor for dividing a DC voltage; and

a DC auxiliary circuit comprising a normal transformer and a half-bridge for overlapping a pulse type input voltage to increase the number of pulses of an output waveform,

wherein the IGBT converter comprises a first converter connected to the Y-Y transformer and a second converter connected to the Y-Δ

transformer,

the capacitor comprises a first DC capacitor connected between a primary side terminal of the transformer of the DC auxiliary circuit and a positive terminal of the first converter, and a second DC capacitor connected between the primary side terminal of the transformer of the DC auxiliary circuit and a negative terminal of the second converter, and

the half-bridge of the DC auxiliary circuit comprises a 3-level half-bridge consisting of first through fourth switching elements connected to the first DC capacitor and the second DC capacitor in parallel and connected to secondary side terminals of the transformer.

2. The converter system in accordance with claim 1, wherein the transformer comprises a primary side coil and a secondary side coil, the primary side coil being connected between a point where a negative terminal of the first converter and a positive terminal of the second terminal are connected and a point where the positive terminal of the first converter and the negative terminal of the second converter are connected, and the secondary side coil being connected to the 3-level half-bridge such that a difference of output voltages are provided,

wherein the 3-level half-bridge comprises a first clamping diode and a second clamping diode, the first clamping diode being connected between a connection point of the first and the second switching elements and a connection point of a second terminal of the primary side coil and a first terminal of the secondary side coil, and the second clamping diode being connected between a connection point of the third and the fourth switching elements and the connection point of the second terminal of the primary side coil and the first terminal of the secondary side coil, and

wherein a second terminal of the secondary side coil is connected to a connection point of the second and the third switching elements.

3. A DC transmission system comprising a back-to-back converter wherein the back-to-back converter includes two of the converter systems in accordance with claim 2, the two of the converter systems being connected to an AC voltage side in serial and connected to a DC voltage side in parallel.