Mipango ya Umeme Inayohusishwa: Ramani ya Mzunguko & Aina
Ni ni Regulated Power Supply?
Regulated power supply hutoa unregulated AC (Mwendo wa umbo) hadi constant DC (Direct Mwendo wa umbo). Regulated power supply hutumika ili kuhakikisha kuwa output ina baki na upimaji wakati input unabadilika.
Regulated DC power supply pia inatafsiriwa kama linear power supply, ni embedded circuit na ina maeneo mbalimbali.
Regulated power supply itatambua AC input na kutokana na constant DC output. Figu ya chini inaelezea block diagram ya typical regulated DC power supply.
Vitamba viwili muhimu vya regulated DC power supply ni kama yafuatayo:
Transformer wa kurudia
Rectifier
DC filter
Regulator
(Tafadhali tuma kwamba digital electronics MCQs yanayojumuisha maswali mengi ya electrical yenye shughuli zinazohusiana na mada hizi)
Ufanyikio wa Regulated Power Supply
Transformer wa Kurudia
Transformer wa kurudia utarudia voltage kutoka kwenye ac mains hadi kiwango cha voltage kinachohitajika. Turn’s ratio ya transformer imebadilishwa kwa njia ambayo inaweza kupata thamani ya voltage inayohitajika. Output ya transformer inatumika kama input kwa rectifier circuit.
Rectification
Rectifier ni circuit ya electronic unaojumuisha diodes ambayo huchukua process ya rectification. Rectification ni process ya kurudia alternating voltage au current hadi direct (DC) quantity. Input kwa rectifier ni AC lakini output ni unidirectional pulsating DC.
Ingawa half wave rectifier inaweza kutumika, matumizi yake ya nguvu ni mingi zaidi kuliko full wave rectifier. Kwa hivyo, full wave rectifier au bridge rectifier hutumika kurektify half cycles zote za ac supply (full wave rectification). Figu ya chini inaelezea full wave bridge rectifier.
Bridge rectifier una diodes nne za p-n junction vilivyoelekezwa kama inavyoonekana hapo juu. Katika positive half cycle ya supply, voltage iliyotokana kwenye secondary ya electrical transformer i.e. VMN ni positive. Hivyo basi point E ni positive kulingana na F. Hivyo, diodes D3 na D2 ni reversed biased na diodes D1 na D4 ni forward biased. Diode D3 na D2 watatenda kama switches zilizofungwa (kwa ujumla kuna voltage drop) na diodes D1 na D4 watatenda kama switches zilizofunguka na wataanza kusimamia. Hivyo rectified waveform itaonekana katika output ya rectifier kama inavyoonekana kwenye figu ya pekee. Waktu voltage iliyotokana kwenye secondary i.e. VMN ni negative, D3 na D2 ni forward biased na wengine mbili ni reversed biased na voltage positive itaonekana kwenye input ya filter.
DC Filtration
Rectified voltage kutoka kwa rectifier ni pulsating DC voltage una ripple content sana. Lakini hii siyo tunavyotaka, tunataka ripple free DC waveform. Hivyo, filter inatumika. Aina mbalimbali za filters zinatumika kama capacitor filter, LC filter, Choke input filter, π type filter. Figu ya chini inaelezea capacitor filter unaoelekea output ya rectifier na output waveform.
