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+// chapter 8
+// example 8.9
+// fig. Ex. 8.9
+// Find the chopping frequency
+// page-463
+clear;
+clc;
+// given
+Edc=400; // in V (dc source)
+L=0.05; // in H
+R=0; // in ohm
+alpha=0.3; // duty cycle
+dI0=8; // in A (load current excursion)
+// calculate
+E0=alpha*Edc;
+Eb=E0;
+// Since VT_area=L*dI0 and VT_area=(Edc-Eb)*Ton, therefore we get
+// (Edc-Eb)*Ton=L*dI0 or 
+Ton=L*dI0/(Edc-Eb); // calculation of ON period of chopper
+// Since alpha=Ton/T, therefore
+T=Ton/alpha; // calculation of chopping period
+f=1/T; // calculation of chopping frequency
+printf("\nThe chopping frequency to limit the load current excursion to %.f A is \t f=%.2f Hz",dI0,f);
+// Note: The answer varies slightly due to precise calculation
+\ No newline at end of file