ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 1 Lecture 23 Operating Modes of the Series Resonant Converter Lecture 23 Resonant and Soft-Switching Techniques in Power Electronics ECEN 5817

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 2 Lecture 23 Next Homework Assignment Problem 1 Conventional hard-switched flyback converter Ringing caused by transformer leakage inductance Limit peak transistor voltage using a dissipative snubber circuit Analyze performance via state plane analysis

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 3 Lecture 23 Series resonant converter

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 4 Lecture 23 Discontinuous Conduction Modes In the “type k” discontinuous conduction mode, the tank rings through k complete half cycles during each half switching period. The output diode rectifiers then become reverse-biased, and remain off until the input bridge transistors switch to initiate the next half switching period. Q: Why do the diodes decide to interrupt the ringing after k half-cycles, instead of k– 1, or k+1, or...?

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 5 Lecture 23 The k = 1 DCM

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 6 Lecture 23 Why the diodes become reverse-biased State-plane explanation

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 7 Lecture 23 Why the diodes become reverse- biased Inductor voltage waveform explanation

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 8 Lecture 23 Summary of results k = 1 DCM M = 1 J < 4/ 

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 9 Lecture 23 The k = 2 DCM

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 10 Lecture 23 Charge Arguments and Averaging

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 11 Lecture 23 State Plane Diagram k = 2 DCM

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 12 Lecture 23 Summary of Results: k = 2 DCM Solution for radii Output plane characteristics Control plane characteristics

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 13 Lecture General Solution for the Steady-State Characteristics of the Series Resonant Converter Mode index k and subharmonic number 

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 14 Lecture 23 Type k CCM Steady-State Solution Elliptical output characteristic with Control plane characteristic

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 15 Lecture 23 Type k CCM Waveforms Switch network output voltage Tank inductor current, odd k (ZCS) Tank inductor current, even k (ZVS)

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 16 Lecture 23 Type k DCM Steady State Solution Type k DCM, odd k Mode boundaries Output voltage and Type k DCM, even k Mode boundaries Output current and Steady-state equivalent circuit model for even DCM: an effective gyrator. The converter exhibits current source characteristics.

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 17 Lecture 23 CCM and DCM Boundaries

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 18 Lecture 23 Complete SRC Characteristics Control Plane

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 19 Lecture 23 SCR Output Characteristics Above Resonance

ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics 20 Lecture 23 SRC Output Characteristics Selected Modes Below Resonance