Puls and Drive Transformers

Pulse transformers are used in high frequency power converters, when it is required to trasfer an electrical pulse from the control to the power stage, keeping the galvanic isolation between the circuits, according to the safety standards related to each different application fields. The electrical signal is applied to the primary side and transferred to the secondary side, to fire power BJTs, power MOSFETs, IGBTs, SCRs, GTOs, TRIACs.

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Switch Mode Transformers

These transformers are the basic part of high frequency power converters. Like standard 50 Hz transformers, they transfer the electrical power from the primary to the secondary side, by changing voltage and current levels and keeping the galvanic isolation of the load from the mains, according to the safety standards related to the different application fields. Usually the mains voltage is rectified by a full-wave diode bridge and a capacitor, the DC link feeds the transformer through an electronic switch (or more than one, depending on the topology) controlled in the range of some tens or some hundreds of kHz.

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Current Transformers

By considering the final application and the purpose, several current transformer kinds are available. Each type has its own specific features, but they all have the same goal: to convert, the input current value in a proportional signal; the accuracy of the measurement depends on the application. Tipically, the current will be the primary current of the transformer, while the secondary winding will be connected to a burden resistance, in order to obtain a voltage signal with the same information of the measured current.

Sirio is specialized in the development and production of three types of current transformers.

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Inductors

The term "inductor" refer to a wide category of inductive components, with a big variety of applications and goals, but they all act like “energy tanks”. For example, by considering the output filtering stage of a high frequency DC/DC converter, the output inductor continuously swaps the electrical energy with the output capacitor. As the inductor function is to contain the variation of current, the current through the inductor is normally mainly direct current with a superimposed high frequency current ripple (at the switching frequency, or its double value, depending on the topology).  Similarly, by considering the Power Factor Correction (PFC) stage of a high frequency converter, there is a high frequency energy swap involving the inductor and the capacitor; in that case, the current through the inductor is mainly composed by the mains frequency harmonic and a superimposed current ripple at the working frequency of the PFC stage. Similar inductors are also used in non-isolated high frequency conversion topologies (Buck, Boost, Buck-Boost), in which the current waveforms change depending on the mode of conduction, that is if the converter works in continuous or discontinuous mode.

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