(a) ll is possible to find a design in which lhe iransistor peuk blocking volluge is less than 300 V, and the peak diode blocking vidtages aie all less (han 35 V, under steady-slale cunditiuns. Design lhe converter such (hat (his is (rue. Specify: (i) (he transistor duly cycle D. (ii] lhe magnetizing induc(ance Lf, referred lo (he primary, 0 ) the (urns ra(ios miiit-Jn.

(h) For yourdesign of pari (a), determine lhe rms currents of (he lour windings. Note thai they donl simply scale by the turns ralios.

6.11 Spreadshee( design.

(a) Develop (he analytical expressions for the Results and Worst-ease stresses of the forward conver(er spreadsheet design example of Table 6.2.

(b) Enter (he formulas you developed in part (a) in(o a согари(ег spreadshee(, and verify (ha( your computed values agree wi(h those ofTable 6.2.

(c) I( is desired (O reduce lhe forward converter peak transistor vohage (O a value no grea(er than 650 V. Modify lhe design numbers to accomplish (his, and briefly discuss the effect on lhe ()(her componen( stresses.

(d) For (hese specificaOtms, what is (be largest possible value uf the Iransistor Litilizadtm of (he CCM forward converter? How should the Spreadsheet design variables be chosen to attain tbe masimum transistor ulilizatiun?

6.12 Spreadsheet design of an isulated Cuk converter. The isolated liuk converter of Fig. 6.40(c) is to be designed to meet the specifications listed in Table 6.2. The converter is to be designed such thai it operates in continuous conduction mode at full load,

(a) Develop analytical expressions for the following quantities:

The maximum and minimum duty cycles, fin CCM operation

The peak voltages and rms currents of both semiconductor devices

The ripple magnitudes of the capacitor voltages and inductor currents

The rms capaciU)r currents

Thetransistorulilizalion f

(b) Enter the formulas you developed in part (a) into a computer spreadsheet. What are the design variables?

(c) For lhe specifications listed in Table 6.2, select lhe design variables to attain what you believe is the best design. Compare the performance ofyour design wilh lhe flyback and forward converter designs ofTable 6.2.

Part II

Converter Dynamics and Control

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