Advanced Industrial Electronics Resonant Power Converters References [1] Kazimierczuk M., Czarkowski D., Resonant power converters, John Wiley and Sons, Inc. 1995 [] Kazimierczuk M., Czarkowski D., Solutions manual for - Resonant power converters, John Wiley and Sons, Inc. 1995 [3] Brown M., Power supply cookbook, Newnes, 001 [4] uo F.., Ye H. Synchronous and resonant DC/DC conversion technology, energy factor, and mathematical modeling, Taylor and Francis Group, 006 [5] Hagerman J., Calculating optimum snubbers, Hagerman Technology, 1995 [6] International Rectifier, AN-978 HV floating MOS-Gate driver ICs, International Rectifier Application Note, (www.irf.com) [7] Hang-Seok Choi, AN-4151 Half bridge C resonant converter design using FSFR-series Fairchild Power Switch, Fairchild Semiconductor Corporation Application Note, 007 [8] STMicroelectronics, AN450 C resonant halfbridge converter design guidline,stmicroelectronics Application Note, 007, (www.st.com) References [9] Bosso C., AND8311/D Understanding the C structure in resonant applications, ON Semiconductor, 008, (www.onsemi.com) [10] Cree Inc., CD0510-Silicon Carbide Schottky Diode, Cree Data Sheet, 006, (www.cree.com) [11] IXYS Corporation, IXDN430 30 amp low-side ultrafast MOSFET/IGBT driver, IXYS Corporation Data Sheet, 004, (www.ixys.com) [1] IXYS Corporation, EVDD 430S/ EVDD 430CY 30A Ultra Fast MOSFET/IGBT driver evaluation board, IXYS Corporation, 003, (www.ixys.com) [13] IXYS Corporation, IXF3N10P Polar Power MOSFET HiperFET, IXYS Corporation Data Sheet, 008, (www.ixys.com) [14] IXYS Corporation, IXFN60N80P PolarHV Power HiperFET MOSFET, IXYS Corporation Data Sheet, 006, (www.ixyys.com) [15] STMicroelectronics, 6599 High-Voltage resonant controller,stmicroelectronics Data Sheet, 006, (www.st.com) [16] Infineon Technologies AG, SKW5N10 fast IGBT in NPT technology, Infineon Data Sheet, 006 1
Introduction PWM and resonant power converting ideas Introduction DC-DC converter MAINS AC 30V/400V ow frequency rectifier, filter with PFC correction DC 30V/560V Vin PWM/Resonant inverter AC High frequency rectifier and filter DC Vout oad PFC Controller Converter Controller Block diagram of a typical PWM/resonant switching power supply Introduction The function of DC-DC converter are as follows: - to convert a DC input voltage (Vin) into a DC output voltage (Vout) - to control the DC output voltage (Vout) against load and mains variations - to reduce the AC ripple on the DC output voltage (Vout) below the required level - to provide isolation between the input source and the load - to protect the supplied system from electromagnetic interference (EMI) - to satisfy various international and national safety standards
Introduction Voltage-switching half-bridge inverters with various resonant circuits Introduction Main features of the resonant circuits: - circuits a), f) and g) supply a sinusoidal output current and are compatible with current-driven high frequency rectifiers - inverters (b)-(e) produce a sinusoidal output voltage and are compatible with voltage-driven rectifier - for the circuits (b)-(g) resonant frequency depends on the load C inverter basics 3
C inverter basics 1 - the ratio of the inductance: A - the equivalent inductance: + ( A + ) 1 + - the undamped natural frequency: 1 1 1 A ω 0 1 1 C ( 1 + )C - the characteristic impedance: 1 Z 0 ω0 ω C 0 C C inverter basics - the loaded quality factor at f 0 : Q ω R 0CR ω0 - the equivalent inductance of the damped circuits: eq 1 + s where s ω 1+ R 1 1 - the resonant frequency: ωr eqc ( 1 + s )C - the quality factor at the resonant frequency: r ( 1 + s ) Qr 1 ω R where Rs ω CR R 1+ R / ωr r s s R Z ( ) 0 Gain M max capacitive region ZCS C inverter basics peak gain inductive region ZVS f f 0 4
C inverter basics Capacitive region current leads the voltage, bridge MOSFETs operate in zero current switching (ZCS). It means that power MOSFETs are turned-off (Vds decreases from Vin to 0) at zero current. Switching-off losses can be neglected. Inductive region current lags the voltage. Power switches are turned-on (Is is increasing from 0 to Ismax) at zero volts (ZVS). Switching-on losses can be neglected. For frequency f sw f 0 the MOSFETs turn on and turn off at zero currents, resulting in zero switching losses and high efficiency. C inverter basics *Taken from Resonant power converters, KazimierczukM.,Czarkowski D.[1] C inverter basics Operating below resonant frequency (ZCS): a) conductive sequence is Q1, D1, Q, D b) there are a few detrimental effects of switching-on MOSFET: - reverse recovery of the antiparallel diode of the opposite switch - second breakdown of the MOSFET parasitic bipolar transistor - discharging of transistor output capacitance (additional losses) - Miller s effect 5
C inverter basics Operating below resonant frequency: d) IGBT transistors or thyristors with antiparallel diode should be used instead of MOSFETs *Taken from SKW5N10 fast IGBT in NPT technology, Infineon Data Sheet, 006 [16] Operating at frequency f sw f 0 : C inverter basics - transistors turn on and turn off at zero currents - efficiency is high because of lack the conducting losses - antiparallel diodes never conduct - output power or output voltage of the converters can not be controlled C inverter basics Operating at frequency f sw > f 0 : - the conduction sequence of the semiconductor devices is D1-Q1-D-Q - MOSFETs operates at ZVS Vds T d Vgs1 Vgs i ZVS Vin t 6
C inverter basics The C resonant converter with a transformer center-tapped rectifier C inverter basics S in ON, D4 is conducting C inverter basics S is ON, D1 D4 are blocked 7
C inverter basics S1, S are OFF, Coss1 id discharging, Coss is charging C inverter basics V Coss Vin+Vf, D1 conducts; S1, S are OFF; D3, D4 are blocked C inverter basics S1 is ON, D3 is conducting 8
C inverter basics S1 is ON; D3, D4 are blocked C inverter basics S1, S are OFF, Coss1 is charging, Coss id discharging C inverter basics S1, S are OFF, V Coss -U f, D is conducting 9
C inverter basics *Taken from AND8311/D Understanding the C structure in resonant applications, Bosso C. ON Semiconductor, 008 [9] C full-bridge converter High frequency rectifiers 10
High frequency rectifiers The features of current driven diode rectifiers: - have to be driven by current source - the DC output current is directly proportional to the amplitude of the input current - the diode threshold voltage U f, the diode forward resistance R f and filter capacitor ESR reduce efficiency of the rectifiers - the center-tapped rectifier has the highest efficiency, while the half-wave has the lowest High frequency rectifiers The features of current driven diode rectifiers: - half-wave and bridge rectifier are suitable high voltage applications because the diode peak reverse voltage is V dm -V 0 - for the half-wave rectifier both the source and the load can be connected to the same ground - the RMS current of capacitor is very high and therefore the capacitor must be rated accordingly - the ES of the filter capacitor may destroy the filtering effect at very high frequency High frequency rectifiers Features of the rectifier: - it has the highest efficiency - its efficiency is low at light loads - its not suitable for high frequency because of increasing the gatedriver power 11
High frequency rectifiers High frequency rectifiers The features of voltage driven diode rectifiers: - have to be driven by voltage source - have a second-order C output filter - the DC output voltage is directly proportional to the amplitude of the input voltage - the peak-to-peak and RMS through the filter capacitor is relatively low - the conduction loss in the ESR of the filter capacitor is low High frequency integrated transformer 1
High frequency integrated transformer The transformer turn ratio: N n t N 1 The real transformer turn ratio: k is the transformer coupling ratio. n k primary secondary m + r nt n n 1+ λ n 1 t m Equivalent load resistance Transformation the load resistance to the primary side of transformer R R n ac N R N p s Equivalent load resistance The half-wave rectifier: n R R ac π The center-tapped transformer and the bridge rectifier: 8n R R ac π 13
C design procedure The design procedure of C converter was taken from STMicroelectronics, AN450 - C resonant half-bridge converter design guideline,stmicroelectronics Application Note, 007 [8]. Design specification: Input voltage range: Vdc.min - Vdc.max Nominal input voltage: Vdc.nom Regulated output voltage: Vout Maximum output power: Pout Resonant frequency: fr Maximum operating frequency: fmax C design procedure Additional info: Parasitic capacitance of the MOSFETs half-bridge: Czvs Dead time of driving circuit: TD General criteria for the design: The converter will be designed to work at resonance at nominal input voltage. The converter must be able to regulate down to zero load at maximum input voltage. The converter will always work in ZVS in the whole operating range. C design procedure The converter circuit 14
C design procedure Step 1 - to fulfil the first criterion, impose that the required gain at nominal input voltage equals unity and calculate the transformer turn ratio: M nom V 1 V V out n 1 n VDC, nom DC, nom Step - calculate the max. and min. required gain at the extreme values of the input voltage range: out V M max n V out DC,min V M min n V out DC,max C design procedure *Taken from AN450 - C resonant halfbridge converter design guidline,stmicroelectronics Application Note, 007 [8]. C design procedure Step 3 - calculate the maximum normalized operating frequency (according to the definition): fmax fn, max fr Step 4 - calculate the effective load resistance reflected at transformer primary side: 8 8 Vout Rac n R n π π Pout Step 5 - impose that the converter operates at maximum frequency at zero load and maximum input voltage, calculating the inductance ratio 1 M λ M min min f f n,max n,max 1 15
C design procedure Step 6 - calculate the max Q value to work in the ZVS operating region at minimum input voltage and full load condition Q ZVS 1 λ 1 M max 95% Qmax 0.95 + M λ M 1 Step 7 - calculate the max Q value to work in the ZVS operating region at no-load condition and maximum input voltage λfn,max TD QZVS C ZVS COSS + C π ( λ + 1) f R n λ acc,max ZVS Step 8 - choose the max quality factor for ZVS in the whole operating range, such that: QZVS min{ QZVS 1, QZVS } max max stray C design procedure Step 9 - calculate the minimum operating frequency at full load and minimum input voltage, according to the following approximate formula: f min f r 1 1 1+ 1 λ M 1 4 Q ZVS 1+ max Qmax Step 10 - calculate the characteristic impedance of the resonant tank and all component values Z 0 Q ZVS R ac 1 Cr πf Z r 0 Z0 r πf r r m λ C design procedure Step 11 - calculate the transformer parameters p( SO ) r + m p( SS ) r primary inductance (with secondary windings open) primary inductance (with secondary windings shorted) n t n 1+ λ transformer turn ratio Next, choose a core with an appropriate A value. N p p( SO) A N N s n t p Find experimentally the core gap (with secondary winding shorted) to satisfy appropriate r value. 16
MOSFETs protection RC Snubbers MOSFETs protection RC snubber designing MOSFETs protection Step 1 you have to know parasitic or parasitic C of the MOSFET half bridge. Calculate characteristic impedance of resonant circuits: If we know If we know C Z πf 1 Z πfc f is the ringing frequency We assume that the initial value of the snubber resistor R Z. 17
MOSFETs protection Then we can calculate value of the snubber capacitor C: 1 C π fr Power dissipation of the resistor is given by expression: P CV f sw Where V is the voltage across MOSFET when it is OFF, f sw is the converter switching frequency. MOSFET drivers The MOSFET drivers have following features: - driving high capacitive load - supply MOSFET gate with high current - low propagation delay - low rise and fall times - low output impedance MOSFET drivers *Taken from AN-978 HV floating MOS-Gate driver Ics, International Rectifier Application Note, [6]. 18
MOSFET drivers Supplying the high-side driver by bootstrap capacitor. Resonant converters controllers The resonant converter controllers features: - variable frequency control of resonant half or fullbridge - high accuracy oscillator - converter protection functions: frequency shift and latched shutdown - Interface with PFC controller - atched disable input - Burst-mode operation at light load - Non-linear soft-start for monotonic output voltage rise Resonant converters controllers *Taken from 6599 High-Voltage resonant controller,stmicroelectronics Data Sheet, 006, [15]. 19
Resonant converters controllers *Taken from 6599 High-Voltage resonant controller,stmicroelectronics Data Sheet, 006, [15]. Resonant converters controllers *Taken from 6599 High-Voltage resonant controller,stmicroelectronics Data Sheet, 006, [15]. Resonant converters controllers *Taken from 6599 High-Voltage resonant controller,stmicroelectronics Data Sheet, 006, [15]. 0
Resonant converters controllers Burst mode *Taken from 6599 High-Voltage resonant controller,stmicroelectronics Data Sheet, 006, [15]. Resonant converters controllers Soft start *Taken from 6599 High-Voltage resonant controller,stmicroelectronics Data Sheet, 006, [15]. High Power MOSFETs *Taken from IXFN60N80P PolarHV Power HiperFET MOSFET, IXYS Corporation Data Sheet, 006, [14]. 1
High Power, Fast Switching Schottky Diodes *Taken from CD0510-Silicon Carbide Schottky Diode, Cree Data Sheet, 006, [10]. Summary