Rui Li - Soft-Switching Technology for Three-phase Power Electronics Converters

8 Chapter 8Figure 8.1 Topology of the CAC ZVS three‐phase grid inverter.Figure 8.2 Sectors of space vector diagram.Figure 8.3 Key waveforms in sector 1‐1.Figure 8.4 Equivalent circuit of the first steady stage.Figure 8.5 Equivalent circuit of the first resonant stage.Figure 8.6 Equivalent circuit of the diode freewheeling stage.Figure 8.7 Equivalent circuit of the Type 2 commutation stage.Figure 8.8 Equivalent circuit of the short‐circuit stage.Figure 8.9 Equivalent circuit of the second resonant stage.Figure 8.10 Equivalent circuit of the second steady stage.Figure 8.11 Equivalent circuit of the first Type 1 commutation stage.Figure 8.12 Equivalent circuit of the third steady stage.Figure 8.13 Equivalent circuit of second Type 1 commutation stage.Figure 8.14 Demonstration of conduction loss models.Figure 8.15 Turn‐off loss measurement circuit and key waveforms.Figure 8.16 Fitted turn‐off loss function of device 1.Figure 8.17 Definitions of the unified inductor model.Figure 8.18 Measurement setup of magnetic core loss.Figure 8.19 Core losses per volume under different frequencies.Figure 8.20 Demonstration of the filter inductor.Figure 8.21 Average value of the volume over capacitance.Figure 8.22 Shape and dimensions of selected heat sink.Figure 8.23 Thermal model of the heat sink.Figure 8.24 3D model of the heat sink with IGBT devices.Figure 8.25 Procedures of optimization design.Figure 8.26 Optimization results of different switching modules.Figure 8.27 Prototype of the improved resonant inductor.Figure 8.28 Prototype of the improved filter inductor.Figure 8.29 Prototype of the improved clamping capacitor.Figure 8.30 Experimental circuit.Figure 8.31 Measured conversion efficiency.Figure 8.32 Measured efficiency and power density.

9 Chapter 9Figure 9.1 Current and voltage waveforms of the resonant inductor.Figure 9.2 Inductor with air gap.Figure 9.3 Equivalent magnetic circuit model.Figure 9.4 Window area A eand cross‐section area A c.Figure 9.5 Triangular inductor current.Figure 9.6 Design flowchart.Figure 9.7 EE55A shape size.Figure 9.8 Sinusoidal components of different frequencies.Figure 9.9 The barrel winding structure.Figure 9.10 Winding loss of different frequencies.Figure 9.11 The definition of the winding.Figure 9.12 Winding loss of each turn in the first order AC component.Figure 9.13 Distribution of winding loss and magnetic field lines.Figure 9.14 The position definition in the core window: (a) 0%; (b) 100%.Figure 9.15 Winding loss in different positions.Figure 9.16 Distribution of winding loss in different positions.Figure 9.17 Winding loss under different winding thickness.Figure 9.18 Distribution of winding loss under different winding thickness....Figure 9.19 Flat winding structure.Figure 9.20 Different structures: (a) structure 1: laminated structure; (b) ...Figure 9.21 Winding loss in different structures.Figure 9.22 Distribution of winding loss in the laminated structure.Figure 9.23 Distribution of winding loss in the interleaved structure.Figure 9.24 Distribution of winding loss and magnetic field lines.Figure 9.25 The position defined in the core window: (a) 0%; (b) 100%.Figure 9.26 Winding loss in different positions.Figure 9.27 Winding loss under different winding thicknesses.Figure 9.28 Distribution of winding loss under different winding thicknesses...Figure 9.29 Comparison of the different winding structures: (a) winding loss...Figure 9.30 Simulation results in a switching period.Figure 9.31 Structure of the resonant inductor.Figure 9.32 Experimental prototype of the resonant inductor.Figure 9.33 Voltage and current of the resonant inductor at 30 kW.Figure 9.34 Experimental tests of winding and core temperature.

10 Chapter 10Figure 10.1 Topology of traditional hard‐switching SiC three‐phase grid inve...Figure 10.2 Grid voltages and grid currents waveforms of unity power factor ...Figure 10.3 Voltage space vector diagram with 12 subsectors.Figure 10.4 Switching patterns of SVM 12: (a) sector 1‐1 and (b) sector 1‐2....Figure 10.5 Topology of soft‐switching SiC three‐phase grid inverter.Figure 10.6 Switching patterns of ZVS‐SVM in sector 1‐1.Figure 10.7 Waveforms of the key components in one switching period in secto...Figure 10.8 Equivalent circuit of the resonant stage for ZVS of the main swi...Figure 10.9 Equivalent circuit of the three‐phase bridges' short‐circuit sta...Figure 10.10 Equivalent circuit of the resonant stage for ZVS of the auxilia...Figure 10.11 Relationship between AC filter inductance L and switching frequ...Figure 10.12 Region for selecting resonant parameters.Figure 10.13 Relationship between DC filter capacitance C dcand switching fr...Figure 10.14 Waveform of clamping capacitor current i Ccin one switching per...Figure 10.15 Values of clamping capacitor current i clat different instants ...Figure 10.16 Two kinds of waveforms of clamping capacitor current i clin one...Figure 10.17 The relationship between the maximum value of clamping capacito...Figure 10.18 Switching loss testing scheme: (a) double‐pulse test and (b) si...Figure 10.19 Pictures of experimental DPT setup: (a) top view and (b) side v...Figure 10.20 Probes calibration: (a) scheme, (b) delay caused by stray induc...Figure 10.21 Switching energy test results of C2M0025120D from DPT setup: (a...Figure 10.22 Loss distributions of hard‐switching SiC inverter with differen...Figure 10.23 Loss distributions of ZVS‐SVM inverter with different switching...Figure 10.24 Loss distributions comparison of hard‐switching inverter ( f s= ...Figure 10.25 Comparison of theoretical conversion efficiencies of hard‐switc...Figure 10.26 Volumes comparison of the key passive components of hard‐switch...Figure 10.27 Waveforms of hard turn‐on and ZVS turn‐on at 40 A: (a) hard tur...Figure 10.28 Measured conversion efficiency of hard‐switching SiC inverter w...Figure 10.29 (a) Prototypes of inductors and (b) volume comparison of the ke...Figure 10.30 Equivalent circuit of the oscillation after the second resonant...Figure 10.31 Simplified high frequency equivalent circuit.Figure 10.32 Topology of the 7‐in‐1 SiC MOSFET module.Figure 10.33 3D model of the 7‐in‐1 SiC MOSFET power module.Figure 10.34 Critical power loop in soft‐switching inverter.Figure 10.35 Layout sizes comparison of original seven discrete devices and ...Figure 10.36 Stray inductance comparison of simulation results.Figure 10.37 Prototype of 7‐in‐1 SiC MOSFET module: (a) DBC top view and (b)...Figure 10.38 Stray inductance measurement of 7‐in‐1 SiC MOSFET power module:...Figure 10.39 Waveforms of the voltage across the effective terminals and the...Figure 10.40 Simulation scheme of stray inductance: (a) two P 1terminals, fo...Figure 10.41 Waveforms of the maximum voltage overshoots after the second re...Figure 10.42 Comparison of maximum voltage overshoot after second resonant s...Figure 10.43 Waveform of resonant inductor current in one switching period....Figure 10.44 Current density comparison of different air gap arrangements at...Figure 10.45 Simulated loss comparison of different air gap arrangements.Figure 10.46 Optimal flux density design for resonant inductor: (a) three tu...Figure 10.47 Fast Fourier Transform (FFT) result of resonant inductor curren...Figure 10.48 Winding loss vs. different copper foil thickness d .Figure 10.49 Prototypes of original resonant inductor and the new designed r...Figure 10.50 Scheme of resonant inductor loss measurement.Figure 10.51 Prototype of the resonant inductor loss measurement circuit.Figure 10.52 Waveforms under 300 kHz and 25.4 Arms current excitation.Figure 10.53 (a) Loss reduction with distributed air gaps and (b) loss reduc...

11 Chapter 11Figure 11.1 Hard‐switching single‐phase full‐bridge inverter.Figure 11.2 Commonly used modulation strategies for single‐phase inverter: (...Figure 11.3 Key output waveforms of single‐phase inverter.Figure 11.4 Traditional single‐phase inverter.Figure 11.5 Single‐phase inverter with APD.Figure 11.6 Typical waveforms of APD capacitor voltage and current.Figure 11.7 Control schematic of the APD bridge.Figure 11.8 Single‐phase ZVS inverter with APD.Figure 11.9 Conventional modulation method for single‐phase inverter with AP...Figure 11.10 Implementation of EA‐PWM for soft‐switching single‐phase invert...Figure 11.11 Comparison of traditional modulation method and EA‐PWM method w...Figure 11.12 Key waveforms of ZVS inverter with APD.Figure 11.13 Equivalent circuit of stage 1 (t 0– t 1): initial stage.Figure 11.14 Equivalent circuit of stage 2 (t 1– t 2): first resonant stage.Figure 11.15 Equivalent circuit of stage 3 (t 2– t 3): freewheeling stage.Figure 11.16 Equivalent circuit of stage 4 (t 3– t 4): current commutation stag...Figure 11.17 Equivalent circuit of stage 5 (t 4– t 5): current boost stage.Figure 11.18 Equivalent circuit of stage 6 (t 5– t 6): second resonant stage.Figure 11.19 Equivalent circuit of stage 7 (t 6– t 7): steady stage 1.Figure 11.20 Equivalent circuit of stage 8 (t 7– t 8): Type 1 commutation stage...Figure 11.21 Equivalent circuit of stage 9 (t 8– t 9): steady stage 2.Figure 11.22 Equivalent circuit of stage 10 (t 9– t 10): Type 1 commutation sta...Figure 11.23 Equivalent circuit of stage 11 (t 10– t 11): energy output stage 3...Figure 11.24 Circuits of the first resonance in stage 2: (a) original circui...Figure 11.25 Circuits of the second resonance in stage 6: (a) original circu...Figure 11.26 Approximate triangular waveforms of i Lr.Figure 11.27 Circuit of the prototype.Figure 11.28 Design of resonant parameters.Figure 11.29 Driving signal‐producing diagram of ZVS single‐phase inverter w...Figure 11.30 Typical driving signal sequence of the ZVS inverter.Figure 11.31 Diagram of the EA‐PWM module.Figure 11.32 Experimental EA‐PWM driving signals.Figure 11.33 Resonant inductor current: (a) theoretical envelopes and (b) ex...Figure 11.34 Decoupling effect of APD: (a) output voltage v invand DC input ...Figure 11.35 Resonant inductor current i Lr, DC‐link voltage v bus, drain‐sour...Figure 11.36 ZVS realization at the phase of 30 o: (a) main switch and (b) au...Figure 11.37 ZVS realization at the phase of 60 o: (a) main switch and (b) au...