Transformerless 3 phase power inverter
AssigneeSemikron GmbH & Co., KG
InventorRichard Shaun Welches
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Abstract
The invention in the simplest form is an improved transformerless 3 phase power inverter topology and control method for power distribution systems. This 3 phase power inverter system provides the necessary output voltage and current waveform regulation, harmonic distortion rejection, very low output impedance, and ultra low DC offset of the output AC power, even when exposed to a high magnitude of the non-linear, single phase, or the unbalanced loading.
Claims21
A transformerless power inverter system for generating a balanced, regulated three phase AC output comprising:
- a DC source;
- a DC-DC converter for regulating said DC source, wherein said DC-DC converter comprises a pair of independent paths having a common neutral;
- a control section with a voltage loop and a current loop for each phase of said three phase AC output, wherein a controller processes a plurality of pulse width modulated switching signals;
- and
- an inverter section coupled to said DC-DC converter and to said control section, wherein said inverter section uses said switching signals to generate said three phase AC output.
A transformerless power inverter system for generating a balance regulated AC output, comprising:
- a DC power source;
- a DC-DC converter having a high frequency (HF) transformer with a center tap coupled to a common neutral, wherein said HF transformer is coupled to said DC source, and wherein said DC-DC converter includes a pair of independent charging paths coupled to said common neutral;
- an inverter section coupled to said DC-DC converter for generating said regulated AC output from said DC source;
- and
- a control section coupled to said inverter section, wherein said control section comprises a phase output controller for each phase of said AC source each said phase output controller having a voltage loop and a current loop, and wherein a processor generates a pulse width modulated signal to said inverter section.
A method for generating a regulated three phase AC output from an inverter, comprising the steps of:
- providing a DC source as an input to said inverter;
- calculating a voltage feedback for each phase of said regulated output with reference to a common neutral;
- calculating a current feedback for each phase of said regulated output;
- comparing a voltage command to said voltage feedback to produce a voltage error;
- multiplying said voltage error by a voltage proportional and integral tern to produce a proportioned voltage signal;
- comparing said proportioned voltage signal to said current feedback and calculating a current error;
- multiplying a current error by a current proportional and integral term to produce a proportioned current signal;
- and
- calculating a pulse width modulated signal for said inverter.
The method for generating a regulated three phase AC output according 14, further comprising a step of rectifying an AC source to generate said DC source.
Dependencies are inferred from the claim text.