Harmonic neutralization of static inverters by successive stagger

• US 5,337,227 A
• Filed: 04/15/1992
• Issued: 08/09/1994
• Est. Priority Date: 04/15/1992
• Status: Expired due to Term

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Stacey, Eric J., Rosa, John
• Primary Examiner(s): Voeltz, Emanuel T.
• Application Number:
  US07/870,128
• Time in Patent Office: 846 Days
• Field of Search: 363/5, 363/39, 363/40, 363/41, 363/43, 363/64, 363/71, 323/361, 307/105
• US Class Current: 363/71
• CPC Class Codes: H02M 1/0064 Magnetic structures combining different functions, e.g. storage, filtering or transformation
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters

Abstract

Quasi-harmonic neutralized inverter systems are provided with interphase transformers connected in a waffle tree configuration and each having a pair of inputs for receiving staggered voltage waveforms, wherein the stagger angle of the voltage waveforms reduces a harmonic component of an output voltage on an output terminal of each interphase transformer. Inverters produce voltage waveforms at phase angles necessary to provide the required stagger angles at the inputs of the interphase transformers in a first stage of the waffle tree configuration. A method for quasi-harmonic neutralization of voltages in an inverter system is also provided, in which interphase transformers, each having a pair of inputs for receiving staggered voltage waveforms, are connected in a waffle tree configuration, such that the stagger angle of the voltage waveforms reduces a harmonic component of an output voltage on an output terminal of each interphase transformer. Voltage waveforms at phase angles necessary to provide the stagger angles are applied to the inputs of the interphase transformers in a first stage of the waffle tree configuration.

Claims

1. A quasi-harmonic neutralized inverter system comprising:

a plurality of center tapped interphase transformers each having first and second inputs for receiving staggered voltage waveforms, wherein a preselected stagger angle of said voltage waveforms reduces a predetermined harmonic component of an output voltage on an output terminal of one of the interphase transformers;

said interphase transformers being connected in a waffle tree configuration; and

a plurality of inverters for producing voltage waveforms at phase angles necessary to provide the preselected stagger angles of the voltage waveforms at the first and second inputs of the interphase transformers in a first stage of said waffle tree configuration.

2. A quasi-harmonic neutralized inverter system according to claim 1, wherein said voltage waveforms are square waves.

3. A quasi-harmonic neutralized inverter system according to claim 1, wherein said inverters are six-pulse inverters.

4. A quasi-harmonic neutralized inverter system comprising:

three output circuits, each including a plurality of center tapped interphase transformers connected in a waffle tree configuration, each of said interphase transformers having first and second inputs for receiving staggered voltage waveforms, wherein a preselected stagger angle of said voltage waveforms reduces a predetermined harmonic component of an output voltage on an output terminal of one of the interphase transformers; and

a plurality of three phase inverters for producing voltage waveforms at phase angles necessary to provide the preselected stagger angles of the voltage waveforms at the first and second inputs of the interphase transformers in a first stage of each of said waffle tree configurations.

5. A quasi-harmonic neutralized inverter system according to claim 4, wherein said voltage waveforms are square waves.

6. A quasi-harmonic neutralized inverter system according to claim 4, wherein said inverters are six-pulse inverters.

7. A method for quasi-harmonic neutralization of voltages in an inverter system, said method comprising the steps of:

connecting a plurality of center tapped interphase transformers each having first and second inputs for receiving staggered voltage waveforms, in a waffle tree configuration, wherein a preselected stagger angle of said voltage waveforms reduces a predetermined harmonic component of an output voltage on an output terminal of the interphase transformer; and

applying voltage waveforms at phase angles necessary to provide the preselected stagger angles of the voltage waveforms to the first and second inputs of the interphase transformers in a first stage of said waffle-tree configuration.

8. A quasi-harmonic neutralized inverter system comprising:

a first center tapped interphase transformer having first and second inputs for receiving first and second voltage waveforms, said first voltage waveform lagging a fundamental component of an output voltage waveform by a first preselected stagger angle and said second voltage waveform leading said fundamental component of said output voltage waveform by said first preselected stagger angle;

a second center tapped interphase transformer having first and second inputs for receiving third and fourth voltage waveforms, said third voltage waveform lagging said first voltage waveform by a second preselected stagger angle and said fourth voltage waveform leading said first voltage waveform by said second preselected stagger angle, said second interphase transformer having an output for producing said first voltage waveform and being connected to the first input of said first interphase transformer;

a third center tapped interphase transformer having first and second inputs for receiving fifth and sixth voltage waveforms, said fifth voltage waveform lagging said second voltage waveform by a third preselected stagger angle and said sixth voltage waveform leading said second voltage waveform by said third preselected stagger angle, said third interphase transformer having an output for producing said second voltage waveform and being connected to the second input of said first interphase transformer; and

four inverters for producing said third, fourth, fifth and sixth voltage waveforms.

9. A quasi-harmonic neutralized inverter system according to claim 8, wherein said voltage waveforms are square waves.

10. A quasi-harmonic neutralized inverter system according to claim 8, wherein said inverters are six-pulse inverters.