Question

Question 4 (15 marks) Figure 4 shows a single-phase diode bridge rectifier supplied from the 230 V, 50 Hz mains via a step- down transformer D2 D SW + n: 1 + 230 V 33mF 20 0 Vo 50 Hz D3 D4 Figure 4 (a) Assuming that the switch SW is open, explain the operation of the rectifier in figure 4 with the aid of the waveforms of the input and output voltages (v, and v) [4 marks (b) With the switch SW open, show that the DC output voltage Vode) is given by 2max Volde) where v, inax sin ot and 2nf is the supply frequency [3 marks With the switch SW open and the DC output voltage Vode) = 24 V , calculate the transformer (c) turns-ratio n [4 marks (d) With the switch SW now closed and the transformer tums-ration found in part (c), calculate the output voltage ripple Avo 4 marks]

Answer 1

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Given V sinat Féom the tpt owefos (Vm Sinat) dut TT GST 2V TT hivend)24 24 TT 37.7V 37.7 26.66V 230 '> 8.63 26.66 n 8.63 9. Hnce nq

Ripple vatge 2PRC So H Nm3t. R 20 C 33mF 3구. 구 2(5e) (2) (33x 3Xlo AV 0.5t V