Inverter and drive key components


Avnet Abacus offers a comprehensive portfolio of EPCOS and TDK branded products for state-of-the-art inverter and drive design


PROTECTION


High inrush currents occur when an inverter or drive is turned on. Such high currents are caused by the extremely low impedance of smoothing capacitors or coils which almost produce short circuits at the moment of switching on. Thermistors acting as inrush current limiters are a low cost solution to this problem whilst input varistors are used to provide surge protection against voltage spikes on the input. Gas surge arresters provide protection for N-PE applications.


Inrush current limiters • Leaded NTC thermistors


Varistors • Leaded varistors • Housed varistors


INPUT FILTERING


EMC requirements include limitation of conducted and radiated emissions, immunity to transients and surges on the power lines, and immunity to levels of external electromagnetic radiation and electrostatic discharge. A combination of EMI filters, line filter capacitors (X and Y) and common-mode chokes combat the effect of common-mode noise produced by the power supply and prevents it from flowing back to the mains line.


Filters and capacitors • EMI filters • X and Y capacitors


Common-mode chokes • Power line chokes • Ferrite cores


• PFC line chokes


Leakage current compensation • Hybrid filters


Arresters • Gas-filled surge arresters


RECTIFICATION


Each AC input phase is rectified by 3 diodes (top diode in the positive direction and the low side diode of the other two phases) so that the peak of the negative half cycle appears positive. The smoothing capacitor smooths the rectified voltage and will be charged to V=√2 x Veff (e.g. for 380V: 380V x √2 = 537V).


Smoothing capacitors • MKP capacitors


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