Increases Modulation Index Range of Selective Harmonic Elimination/Compensation
This circuit design based on four-quadrant modulation improves upon the main failing of both selective harmonic elimination/compensation (SHC/SHE), limited modulation index range. Conventional solutions that use SHC and SHE in power conversions to control undesired harmonics are restricted by this limited range. Because University of Florida researchers have found that the constraint of switching angle range is the most critical factor limiting the modulation index range, they have developed a design using four-quadrant modulation transforming transcendental equations to geometry-based diagrams, to significantly extend the modulation index range. This allows for broader industrial applications of SHC/SHE because it provides more efficient and controlled power conversion for systems that require high switching efficiency, control and current quality. Embodiments of this design can be applied to a wide range of devices and topologies.
Application
A four-quadrant switching angle modulation technique for a larger modulation range in power conversion
Advantages
- Much lower switching frequency, offering higher efficiency and less power loss
- Improved current quality, protecting electronic equipment from surges
Technology
A variety of electrical applications are increasingly using multilevel power. Selective harmonic elimination and compensation (SHC/SHE) can optimize performance of electronic devices by reducing unwanted harmonics. However, these techniques have a limited effective modulation index range, restricting their potential applications. By converting the transcendental equations into geometry-based diagrams, UF researchers have discovered that the crucial limiting factor is the constraint of the switching angle range. To remove this limitation, they have developed a design that uses four-quadrant modulation to extend the modulation index range. The four-quadrant design can determine switching angles without limitations, detect switching angles in undesired states, and transform them into desired states while leaving other angles alone. The improved control over the switching angles and lack of constraint increases the modulation index range, allowing SHC and SHE to be applied much more broadly.
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