Rectifier Diode Characteristics
Technically, ? rectifier diode ?s ?n? diode us?d ?n ? rectifier circuit. In fact, m??t diodes u??d ?n power rectification applications ar? n?thing m?re th?n common switching diodes. However, th?r? ?r? diodes mad? ?speciall? f?r u?? ?n rectifiers th?t mu?t convert large amounts ?f power. Th?se rectifier diodes, al?? called power diodes, ?r? essentially ju?t simple switching diodes, however, th?? h?ve ? mu?h mor? robust ?nd heavy-duty construction th?n d? standard diodes t? handle mu?h heavier workloads.
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Rectifier Operation
AC power?s voltage continuously chang?s fr?m positive t? negative th?n ba?k again, allowing electrical current t? flow ?n tw? directs ?? well, forming ? sort ?f continuous wave. However, DC devices require power maintained ?t ? continuous voltage level ?nd h?s current flowing ?n ?nly on? direction l?ke ? straight line. Th? process ?f converting th? AC wave t? ? DC straight line ?? rectification, wh??h literally means t? put ?t straight. Th? ability ?f diodes t? ?llow current t? flow ?n ?nly ?ne direction ?s key t? th? operation ?f ?ll rectifiers.
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Types ?f Rectifiers
Th?re ?re tw? basic types ?f rectifiers: h?lf wave rectifiers ?nd full wave rectifiers. H?lf wave rectifiers, ?s th? nam? suggests convert h?lf ?f th? AC wave t? DC power u??ng ?s f?w a? ? single diode. Full wave rectifiers convert th? full AC wave ?nd c?n us? ?s f?w ?s tw? diodes. Th?r? ar? variations ?n b?th ?f th?se types ?f rectifiers ?u?h ?? th? full wave bridge rectifier, whi?h us?s f?ur diodes.
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Full Wave Rectifiers
In ? simple full wave rectifier, tw? diodes ?nd ? center-tapped transformer m?k? u? th? circuit. Wh?n th? positive h?lf ?f th? AC wave passes, ?ne diode all?ws current flow ?ust ?s ?n ? h?lf wave rectifier. However, wh?n th? ?e?ond h?lf ?f th? wave passes, ?t travels thr?ugh th? s?c?nd diode ?n ? reversed polarity. In th?? way, b?th th? positive ?nd negative halves ?f th? AC wave ?r? rectified, ?nd combined, providing continuous current flow.
Full Wave Rectifier
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H?lf Wave Rectifiers
In ? simple h?lf wave rectifier, th? diode all?ws th? positive h?lf ?f th? wave t? pass thr?ugh it. Wh?n th? wave reaches it? negative half, th? current reverses ?nd th? diode blocks th?t portion. Th?? creates ? sort ?f ?n ?nd ?ff pattern wh?r? th? positive h?lf ha? current flow but th?re ?s n?ne dur?ng th? time ?t takes f?r negative h?lf ?f th? wave t? pass. Oth?r types ?f devices, ?u?h a? capacitors, ?an h?lp average th?? out, however, f?r man? types ?f devices th?? i? adequate rectification.
Half Wave Rectifier
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Peak Loss
An aspect ?f m??t rectification ?s ? loss fr?m peak input voltage t? th? peak output voltage, caused b? th? threshold voltage ?f th? diodes (around 0.7 V f?r ordinary diodes ?nd 0.1 V f?r Schottky Diodes). H?lf wave rectification ?nd full wave rectification u?ing tw? separate secondaries w?ll h?ve ? peak voltage loss ?f ?ne diode drop. Bridge rectification w?ll hav? ? loss ?f tw? diode drops. Th?? ma? represent significant power loss ?n ver? l?w voltage supplies. In addition, th? diodes w?ll n?t conduct bel?w thi? voltage, s? th? circuit i? ?nl? passing current thr?ugh f?r ? portion ?f e?ch half-cycle, causing short segments ?f z?r? voltage t? ??p??r betwe?n ?ach ?pump?.
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Rectifier Diode ?n Circuit
Rectifier diode circuits ?bv?ousl? rely ?n diodes f?r the?r operation. Diodes ?re devices th?t onl? pass current ?n on? direction. Wh?n Ambrose Fleming invented th? fir?t diode, h? called ?t ? valve b???us? ?f ?ts on? wa? action. Semiconductor devices ?re n?w us?d ?nd th?se provide ?x?ctly th? ?am? function.
In th? f?rw?rd direction, ? small voltage i? required a?ros? th? diode b?f?re ?t conducts - th? turn ?n voltage. Th? actual voltage depends ?n th? type ?f rectifier diode ?nd th? material used. F?r ? standard silicon rectifier diode thi? turn ?n voltage ?? ?r?und 0.6 volts.
In th? reverse direction, th? diode rectifier w?ll ultimately break down. Th? breakdown voltage ?? n?rmall? w?ll ?n excess ?f th? turn ?n voltage.
Ther? ?re m?n? d?ff?r?nt types ?f rectifier diodes th?t ??n b? us?d - ??ch on? w?th ?t? ?wn properties, advantages ?nd disadvantages.
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