91download.com supports a wide range of platforms, including YouTube, Facebook, Twitter, TikTok, Instagram, Dailymotion, Reddit, Bilibili, Douyin, Xiaohongshu and Zhihu, etc. Click the download button below to parse and download the current video
In the realm of power electronics, inverters play a pivotal role in converting DC power to AC power. The quest for a pure sine wave output has driven engineers to explore various techniques, and two standout methods are harmonic elimination and harmonic cancellation. In this article, we'll delve into these fascinating strategies that enhance inverter performance.
Inverters, typically equipped with four switches like MOSFETs, generate waveforms across a load. By manipulating these switches, we can create positive, negative, or zero voltages across the load, approximating a sine wave. This pursuit is crucial for applications like UPS inverters, where replicating the grid's sine wave is essential.
To shape the waveform's harmonic content, we turn to the Fourier series, which decomposes a signal into its constituent sine and cosine waves. Half-wave symmetry, a key concept, ensures that even harmonics are eliminated, simplifying the filtering process.
Harmonic elimination involves introducing carefully timed pulses to cancel specific harmonics. By adjusting the angle delta, we can control the fundamental component and selectively eliminate harmonics like the third, fifth, or seventh. This technique, while effective, increases switching losses due to the higher frequency of switching.
Harmonic cancellation takes a different approach, utilizing two inverters with phase-shifted waveforms. By adding these waveforms, specific harmonics cancel out, resulting in a waveform closer to a pure sine wave. This method requires precise control of phase shifts but offers a more efficient solution compared to harmonic elimination.
Three-level waveforms, with three voltage levels (0, VDC/2, VDC), provide greater flexibility in harmonic cancellation. By carefully selecting the phase shifts, engineers can eliminate multiple harmonics simultaneously.
Interleaving, another technique, involves using multiple converters with phase-shifted switching to reduce the ripple current and increase the ripple frequency. This results in easier filtering and improved performance.
Harmonic elimination and cancellation are widely used in various applications, from inverters to DC-DC converters. As technology advances, we can expect more sophisticated circuits and techniques to further refine these methods, leading to even purer waveforms and improved efficiency.
Harmonic elimination and cancellation are powerful tools in the quest for a pure sine wave output from inverters. By understanding and applying these techniques, engineers can unlock the full potential of inverter technology, paving the way for a more efficient and sustainable future.
Share on Twitter Share on Facebook