Question

As a power electronics engineer, you have been contracted by a mobile phone manufacturing company, STK Mobile, to design a converter to supply power to the microprocessors for the mobile phones. Your task is to design a converter to meet the following specifications:

1. the microprocessors operate effectively at 8 V and 1 A.

2. continuous current conduction mode at all the time.

3. peak-to-peak inductor current should not be more than 30% of its average value at all operating conditions.

4. output voltage ripple should not be more than 2%.

NOTE: Typical output voltage of batteries for the mobile phones range from 3.6 V to 12 V DC, depending on the charge state.

(a) block diagram, explaining how the whole system would operate.

(b) your choice of converter(s) and its (their) circuits. Explain the operation of your choice of converter(s).

(c) derive expressions for the relationships between output and input voltages and currents for your choice of converter (s).

Answer 1

a) •> Block Diagram TDC-DC convoy LOAD y switch mode + Full Bridge LC type { filtered Feedback <Rectifier)

by Full Bridge Rectifier *) Explanation ~ from the AC power supply, sinusoidal voltage will be converted to de filter will reduce ripple of de wave sm de-de converter will reduce the magnitude of de voltage. → Feedback will help to maintain constant de output voltage LI To RL AP3 Vo(+) -C2 D5 EN 263 DI + GolZ L2 D4 D2 OF Gate eek v=230V <ce=Control circuity Di, D2, D3, D4 - Normal diodes D5 = High frequency diode: so power mosfet (IRFP450) Ti = Flyback transformer,

exeplanation through diagram 个 Vo 'N2 The converter used as de-de conversion medium is - Flybaew converted, Design of flyback converter Assuming V2 → purede, ID V2} {D = Duty ratio) Lets set, (Nz/N1) (1:10) so, As, V2 = 2(%) 2 for, Vo= qV; vo 207.07 V

De Ni IN2 z (Vo/v2) 0:38 whew, soni N2 2) V2 = 22.11n {t,= D/) + Vo Whew, st off: di tvo=0 dta {+2. =(-D)) 2 12 di using equeo and (di) = A IL = N2 x VzxD(1-0) mi fekk 2010) 0.3 A Lets, say, f = 100 kHz ( switching freq. ofs) for, AIL = 307, of IA Nz V₂ D (1-D) Ny f L₂ 50, < 013 so, L2 > 48.78 MH Lets, take, L2 = 50ult

Again, it can be shown that AVO N2 V2.D(ID) Ni 8 frezLz As, given that, avo 2. Of 8V 0.16V Sog C3 ) 1.21 MF so, Lets take, C3 = 13 MFI Filter design! L1 = 10,MH 1 This will give smooth C2 = I'm F de output. *> explanation Flyback conv. through graph I 229 [EDIf Iole