Within a power converter, multiple currents are usually measured for control, protection, and/or monitoring. They are therefore important sources of information, which must unquestionably be measured accurately to maintain continuous and reliable operation of the power converter. Accurate current measurement has however become tougher with the introduction of wide band-gap (WBG) devices with switching frequency tending towards the Megahertz (MHz) range. Because of that, the installed current sensors must have a significantly widened bandwidth. Moreover, they must be nonintrusive and compact, in order not to degrade fast switching characteristics and high power density of the WBG converter. Presently, these features are not collectively obtainable from existing commercial current sensors. Consequently, many new current sensing techniques have surfaced in the literature for usage with the more demanding MHz power converter. These new techniques, some classical techniques, and their hybrid integrations are now reviewed, after overviewing functionalities made possible by current sensors in a power converter. Last but importantly, some future developmental trends aimed at matching MHz current sensors with MHz power converters are described, before concluding the paper.
Two bandpass filters (BPFs) are implemented on a single dual‐mode square‐shaped substrate‐integrated waveguide (SIW) cavity with two etched coplanar waveguides. The proposed BPFs can achieve two transmission zeros (TZs) using dual modes in the SIW cavity (i.e. TE102 and TE201) with non‐resonating mode (i.e. fundamental TE101), which provides a direct input‐to‐output coupling. Moreover, the positions of the two TZs can be tuned by changing the positions of input and output ports. Moreover, an extra TZ with controllable position is also achieved by using controllable electric and magnetic mixed coupling; and the TZ also can be split into two TZs for the mixed cross‐coupling paths. The BPFs with the controllable TZs improve the selectivity and out‐of‐band rejection. The designed BPFs have a centre frequency of 5.8 GHz. The measured results agree with the simulated ones.
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