Power electronics Chapter 7 Soft-Switching Techniques
PPoowweerr EElleeccttrroonniiccss Chapter 7 Soft-Switching Techniques
PEREE Pursuing of higher switching frequency Better waveform PWM waveform will be closer to expected waveform Harmonics is easier to be filtered Benefits Smaller volume and weight 4. 44fN0=4.44fNAB 2√LC Faster response 2
Power Electron cs i 2 Pursuing of higher switching frequency Pursuing of higher switching frequency Better waveform • PWM waveform will be closer to expected waveform • Harmonics is easier to be filtered Faster response Smaller volume and weight • 4.4 4fNφ =4.44fNAB • LC f 2 π 1 = Benefits
PEREE Disadvantages of higher switching frequency Disadvantages 4 Higher power losses on power semiconductor devices Power loss=f x Energy loss at each switching More severe electromagnetic interference(EMD) Steeper edges introduce more noises Easier to be radiated Solution 4 Soft-switching techniques 3
Power Electron cs i 3 Disadvantages of higher switching frequency Disadvantages of higher switching frequency Disadvantages Disadvantages Higher power losses on power semiconductor devices Higher power losses on power semiconductor devices – Power loss= Power loss=f x Energy loss a f x Energy loss a t each switching each switching More severe electromagnetic interference (EMI) More severe electromagnetic interference (EMI) – Steeper edges introduce more noises Steeper edges introduce more noises – Easier to be radiated er to be radiated Solution Solution Soft -switching techniques switching techniques
PEREE Outline 7. 1 Basic concepts on soft-switching 7. 2 Classification of soft-switching techniques 7. 3 Typical soft-switching circuits and techniques
Power Electron cs i 4 Outline Outline 7.1 Basic concepts on soft Basic concepts on soft-switching switching 7.2 Classification of soft 7.2 Classification of soft-switching techniques switching techniques 7.3 Typical soft 7.3 Typical soft-switching circuits and techniques switching circuits and techniques
PEREE 7.1 Basic concepts on soft-switching Hard-switching u a)Turning-on b)Turning-off The process of power semiconductor device hard-switching 5
Power E l ect r o n cs i 5 7.1 Basic concepts on soft Basic concepts on soft-switching switching Hard-switching switching t u i u i t u i u i t p t p O O O O a) Turning-on b) Turning-off The process of power semiconductor device The process of power semiconductor device hard-switching switching
PEREE The concept of soft-switching Soft-switching u a)Turning-on b)Turning-off The process of power semiconductor device soft-sWItching
Power E l ect r o n cs i 6 The concept of soft The concept of soft-switching switching Soft-switching switching a) Turning-on b) Turning-off t u i u i t u i u i t p t p O O O O The process of power semiconductor device The process of power semiconductor device soft-switching switching
PEREE Two types of soft-switching ZVs--Zero-voltage switching 4 Specifically means zero-voltage turn-on, i.e,the voltage across the device is reduced to zero before the current increases Zcs-Zero-current switching Specifically means zero-current turn-off, i.e., the current flowing through the device is reduced to zero before the voltage increases 7
Power Electron cs i 7 Two types of soft Two types of soft -switching switching ZVS —Zero -voltage switching voltage switching Specifically means zero Specifically means zero -voltage turn voltage turn -on, i.e., the on, i.e., the voltage across the device is reduced to zero before the voltage across the device is reduced to zero before the current increases current increases ZCS —Zero -current switching current switching Specifically means zero Specifically means zero -current turn current turn -off, i.e., the off, i.e., the current flowing through the device is reduced to zero current flowing through the device is reduced to zero before the voltage increases before the voltage increases
aeRe 7.2 Classification of soft-switching techniques 4 Quasi-resonant soft-switching ZVS PWM(zero-voltage-switching PWM)and ZCS PWM(zero-current-switching PWM) ZVT PWM(zero-voltage-transition PWM) and ZCT PWM zero-current-transition PWM)
Power Electron cs i 8 7.2 Classification of soft Classification of soft -switching switching techniques techniques Quasi -resonant soft resonant soft-switching switching ZVS PWM (zero ZVS PWM (zero -voltage voltage -switching PWM) and ZCS switching PWM) and ZCS PWM (zero PWM (zero -current current-switching PWM) switching PWM) ZVT PWM (zero ZVT PWM (zero -voltage voltage -transition PWM) and ZCT transition PWM) and ZCT PWM (zero PWM (zero -current current-transition PWM) transition PWM)
PEREE The concept of basic switch cell S VD VD a) b S d)
Power E l ect r o n cs i 9 The concept of basic switch cell The concept of basic switch cell VD S L a) L S VD L S VD c) d) VD S L b)
PEREE Quasi-Resonant Converter--QRc 4 ZVS QRC ◆ ZCS QRO 4 ZVS MRC (multi-resonant converter) Resonant DC link converter VD 2)不VD a)ZVS QRC b)ZCS QRC c)ZVS MRC Basic switching cells for QRC
Power Electron cs i 10 Quasi -Resonant Converter Resonant Converter—QRC ZVS QRC ZVS QRC ZCS QRC ZCS QRC ZVS MRC (multi ZVS MRC (multi -resonant converter) resonant converter) Resonant DC link converter Resonant DC link converter S VD Lr L Cr S VD Lr L Cr1 Cr2 S Lr Cr VD L a) ZVS QR C b) ZCS QRC c) ZVS MRC Basic switching cells for QRC
