1 Quasi-square-wave ZVS converters A quasi-square-wave ZVS buck Resonant transitions but transistor and diode conduction intervals are similar to PWM Tank capacitor is in parallel with all semiconductor devices, hence all semiconductors operate with ZVS Peak currents are increased, and are similar to DCM Peak voltages applied to semiconductors are same as PWM Magnetics are small, and are similar to DCM

2 Quasi-square-wave versions of other converters Boost Flyback Single transistor version of switch is restricted to 0.5 < µ < 1 So for boost, M > 2 For flyback, M > n Boost inductor and flyback transformer are very small, and are similar to DCM devices

3 Interleaved quasi-square-wave buck converters as VRM

4 Waveforms

5 State plane

6 Interval 1 Q1 conduction

7 Interval 2 Resonant transition

8 Interval 3 Diode D2 conduction

9 Interval 4 Resonant Transition

10 Interval 5 D1 conduction

11 Average switch input current

12 Length of switching period

13 Another approach: Find dc component of output current

14 Average output current, p. 2

15 Control input: transistor/diode conduction angle 

16 A way to solve and plot the characteristics

17 Solving, p 2

18 Results: Switch conversion ratio µ vs. F

19 Switch conversion ratio µ vs.  Course website contains Excel spreadsheet (with function macros) that evaluates the above equations and can plot the above characteristics.