Improving Grid Inverter Reliability with Harmonic Control
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Summary
Problems
Grid-interactive inverters face challenges in maintaining high output current quality, power production, and reliability due to issues like total harmonic distortion and inefficiencies in DC-AC conversion, as well as reliability concerns such as inrush currents and overcurrent events.
Innovation solutions
The implementation of a grid-interactive inverter system that includes a controller for bidirectional switching across output terminals, performing frequency decomposition of output currents to subtract unwanted components, optimizing switching times in DC-DC conversion stages, and incorporating circuits for inrush current limiting and overcurrent protection, along with power line communication and error correction for improved reliability.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If frequency decomposition and harmonic cancellation are implemented, then output current quality is improved, but device complexity increases
Why choose this principle:
The controller measures the output current, performs frequency decomposition to identify harmonic components, and generates control signals to cancel unwanted harmonics. This closed-loop feedback mechanism continuously monitors and corrects output current quality, resolving the contradiction by automating the complex harmonic cancellation process through intelligent control rather than complex hardware.
Principle concept:
If frequency decomposition and harmonic cancellation are implemented, then output current quality is improved, but device complexity increases
Why choose this principle:
The patent replaces complex passive filtering hardware with active electronic control. Instead of using large, complex passive filters to remove harmonics, the system uses the controller to generate compensating signals that actively cancel harmonics, substituting mechanical/electrical filtering with electronic signal processing.
Application Domain
Data Source
AI summary:
The implementation of a grid-interactive inverter system that includes a controller for bidirectional switching across output terminals, performing frequency decomposition of output currents to subtract unwanted components, optimizing switching times in DC-DC conversion stages, and incorporating circuits for inrush current limiting and overcurrent protection, along with power line communication and error correction for improved reliability.
Abstract
Various enhancements to grid-interactive inverters in accordance with embodiments of the invention are disclosed. One embodiment includes input terminals configured to receive a direct current, output terminals configured to provide an alternating output current to the utility grid, a controller, an output current sensor, and a DC-AC inverter stage comprising a plurality of switches controlled by control signals generated by the controller. In addition, the controller is configured to: generate control signals that cause the switches in the DC-AC inverter stage to switch a direct current in a bidirectional manner; measure the alternating output current; perform frequency decomposition of the output current; and generate control signals that cause the switches in the DC-AC inverter stage to switch current in a way that the magnitude of a plurality of unwanted current components is subtracted from the resulting output current.