Experiment 3Power Supply Design ProjectEE 310, Section 001Tianyu LiTA: Mei LeiIntroductionIn this experiment, we are going to design a power supply which includes the input transformer, rectifier, filter and voltage regulation blocks. And the power supply we use in this experiment is 120 volt 60 Hz input, and we are going to convert it to a 12 volt dc voltage output voltage and the maximum ripple voltage should not excess 15% of Vc with rated load resistance attached. The nominal DC voltage at regulator input is 24 V, and DC output voltage should be 150.5V.Circuit Design and ReasoningBlock Diagram of power supply:

1. Power Transformer:

The ratio of this transformer is 12:1:1, VAC = 120 * 2 / 120 = 20 VRMS2. Schematic of rectifier without filter capacitor:

The full-wave bridge rectifier is use in this experiment to make the output voltage 24V. The current goes from D1, Rtest, and D4. 3. Schematic of rectifier with filter capacitor:

Capacitor is on parallel with Rtest making a capacitor filter circuit. The calculated value of capacitor is 130, but we only have 47, 100, 220, and 470. So we put 47 and 100 together to make the 147 and its work. 4. Schematic of zener diode regulator:

The circuit above, the voltage is 24 volts and the breakdown voltage of zener diode is 15 V. We use 1N4738 and 1N4736 which add together are exactly 15V breakdown voltage.5. IC Voltage regulator

Supporting Analysis1. Power transformer.The ratio of this transformer is 12:1:1 = Vrms:VAB:VBC.VAB = VBC = 10 Vrms, VAC = 20.7 Vrms. 2. PIVPIV = 2Vs Vo = 2*10 1 = 19 v3. Resistor and CapacitorRtest = (VAC2)/1W = 202/1 = 400 ohmsWe use 552 ohms in experiment. Rw = Rtest( (Vwithout Rtest Vwith Rtest)/(2* Vwithout Rtest))= 3.14 ohmsVm = 28.2 V VL = 24.3 V Vr = 15%* VL = 3.6 VVc =24VRL=(Vc)2 /1w = (24)2 /1= 576 ohmsC = 120 4. Maximum diode currentVmax= 220mVIdmax=Vm/Rl(1+2pi*sqrt(Vm/2Vr)= 275mA (Vm and Vr in magnitude value)

The measured value much smaller than this value which is 0.22A.The reason is there might be some resistance on the wire but its almost correct, and they are almost same. 5. Multism simulation of diode current

The iDmax is 27.35mA.6. Regulator parameterVz=3*8.2+3*0.7=26.7VIzmax = Pz/Vz=18.73mAIzmin = 30%Izmax=5.619mARi=(Vc-Vz)/Izmax= 144 ohmsRiactual=142.5 ohmsRL = Vz/(Izmax- Izmin)= 2036ohmsRLactual=1.97 kohmsData1. Transformer:VAB= 10 Vrms VBC= 10 Vrms VAC= 20 VrmsRw = 3.14 ohms1. Plot of rectifier input and output

1. Plot of transformer output:

1. Zener diode regulator waveform:Full load:

Without load:1. IC regulator waveformWith load

Without load

1. IC regulator with AC ripple waveform

1. Calculations and comparison:Zener voltage regulator:=1.67%IC voltage regulator:=0.067%RL=VL/Izmax = 801 ohmsRLactual=808 ohms1. Power dissipation and marginPRtest= (IRtest)2 * Rtest = (27.4mA)2 * 500ohms=0.38WPdiode= Vturn on * I= 0.7 * 0.0274= 0.019WAs the datasheet of diode 1N4004 mentioned, the power dissipation is 3W. The value in experiment is 0.019W which is much lower than the margin level. 2 watts 500ohms Rtest is used, which indicates that the safety margin should below 2W. The calculated value is 0.38 watt which is lower than 2 watt. DiscussionThe 120 Vrms 60 Hz input is used and 12:1:1 step down transformer is placed in the circuit to reduce the voltage from 120 Vrms to 20 Vrms. The power dissipations are all in the safe values which component values are at least 2 times greater than the calculated values. Our groups percentage error is under 2%, and its really nice data we got. And the outputs we got are almost matching the design specifications we made before the lab, so anyway, our design is being success. Conclusion and SummaryFrom this experiment, we learn that how to design the input transformer, rectifier, and filter circuits of the simple linear regulated power supply, and also learn that how the zener diode works in its breakdown voltage, and the comparison its performance with 3-terminal IC voltage regulator, and for this experiment our data is really accurate, the percentage error is only about 1.5%, we think we can doing better in the future labs.