Loss Analysis And Soft-Switching Behavior Of Flyback-Forward High Gain .
84Journal of Power Electronics, Vol. 16, No. 1, pp. 84-92, January (Print): 1598-2092 / ISSN(Online): 2093-4718JPE 16-1-10Loss Analysis and Soft-Switching Behavior ofFlyback-Forward High Gain DC/DC Converters witha GaN FETYan Li†, Trillion Q. Zheng*, Yajing Zhang*, Meiting Cui*, Yang Han**, and Wei Dou**†,*School of Electrical Engineering, Beijing Jiaotong University, Beijing, China**Beijing Corona Science & Technology Co.,Ltd, Beijing, ChinaAbstractCompared with Si MOSFETs, the GaN FET has many advantages in a wide band gap, high saturation drift velocity, highcritical breakdown field, etc. This paper compares the electrical properties of GaN FETs and Si MOSFETs. The soft-switchingcondition and power loss analysis in a flyback-forward high gain DC/DC converter with a GaN FET is presented in detail. Inaddition, a comparison between GaN diodes and Si diodes is made. Finally, a 200W GaN FET based flyback-forward high gainDC/DC converter is established, and experimental results verify that the GaN FET is superior to the Si MOSFET in terms ofswitching characteristics and efficiency. They also show that the GaN diode is better than the Si diode when it comes to reverserecovery characteristics.Key words: EPC, Flyback-forward, GaN FET, GaN Schottky diode, High gain, Loss analysisI.INTRODUCTIONWith the ever increasing power demands of modern systems,as well as the desire for reduced size and lower powerconsumption, high power density and high efficiency are thekey drivers for the advancement of power conversiontechnologies. However, devices based on Si semiconductormaterials are approaching the limits of physical performancewith respect to lowering power conversion losses, particularlyin terms of reducing conduction resistance and switching loss.Wide band-gap semiconductor materials such as silicon carbide(SiC) and gallium nitride (GaN) have many advantagesincluding a wide band gap, high saturation drift velocity, highcritical breakdown field, etc. As a result, wide band-gapsemiconductor devices are more suitable for high-frequency,high-temperature, high power density and high efficiencyapplications [1]-[4]. Currently, a series of breakthroughs onSiC devices have been made. However, the research andManuscript received Apr. 9, 2015; accepted Jul. 31, 2015Recommended for publication by Associate Editor Joung-Hu Park.†Corresponding Author: liyan@bjtu.edu.cnTel: 86-010-51687064-21, Beijing Jiaotong University*School of Electrical Engineering, Beijing Jiaotong University, China**Beijing Corona Science & Technology Co.,Ltd, Beijing, Chinaapplication of GaN devices is still limited [5]-[8]. EPC,Transphorm, GaN systems and Panasonic Inc. have GaNdevices. These GaN devices can be categorized into two typesdefined by their physical structure: single enhancement modeand cascade mode. In these devices, a low voltage Si MOSFETis in series to drive a depletion mode GaN HEMT. Comparedto cascade mode devices, these enhanced mode devices usuallyhave a lower on-resistance and smaller size. As a result, theyare more attractive for high efficiency and high power densityapplications.The authors of [9]-[13] studied the application of EPCenhanced mode GaN devices to MHz Buck converters andLLC resonant converters. They also discussed the impact ofGaN device layout, magnetic components and distributionparameters on circuits. [13] shows the 3-D IntegratedGallium-Nitride-Based Point of Load Module Design in detail.References [14], [15] presented a 90 W AC/DC adapter,which is composed of a buck-PFC stage and aQuasi-Switched-Capacitor (QSC) resonant DC/DC converter.The Buck-PFC evaluation module from TI Inc. achieves 97.1%peak efficiency with a GaN HEMT (TPH3006PD) and a SiCSchottky diode (C4D20120A) at 100 kHz. The 85 V/19 V. 1MHz QSC resonant converter uses 100 V EPC eGaN FETs. Inthis case a 10.5 W/cm3 power density and 92.8% peak 2016 KIPE
85Loss Analysis and Soft-Switching Behavior efficiency at 900 kHz are obtained.This paper compares both the electrical properties of GaNFETs based on EPC and Si MOSFET, and the electricalcharacteristics of GaN Schottky diodes and Si fast recoveryepitaxial diodes with the same voltage level. An evaluation of aGaN FET based on a flyback-forward high gain DC/DCconverter at the soft-switching condition is presented in detail.A power loss analysis of the GaN FET based flyback-forwardhigh gain DC/DC converter is discussed in detail. Finally, a200W GaN FET based flyback-forward high gain DC/DCconverter is established.Fig. 1. Structure of GaN FET.6040200-20II. STRUCTURE AND CHARACTERISTICS OF THEGAN FETA. Structure and Characteristics of the GaN FETFig. 1 shows the structure of a GaN FET. Si material isused as the substrate in the GaN FET, and a GaN crystal layerwith a high resistance is grown on the basis of the Si substrate.An aluminum nitride (AlN) insulating layer is added betweenthe GaN layer and the Si substrate layer isolating the deviceand the substrate. An AlGaN layer exists between the GaNlayer and the gate (G), the source (S) and the drain (D)electrodes, and two-dimensional electron gas (2DEG) withhigh electron mobility and low resistance can be generatedbetween the AlGaN layer and the GaN layer.The device is voltage-controlled. When the positivegate-source voltage is greater than the threshold voltage, thegate is enabled, and with the 2DEG formed the transistor isturned on. When this is not the case, the transistor is turnedoff.A GaN FET is a lateral structure device, as shown in Fig. 1.Unlike a Si MOSFET, a GaN FET has no parasitic bodydiode. There is no P-type parasitic bipolar region connectedto the source electrode under the gate electrode of a GaN FET.This structure makes the GaN FET have a symmetricaltransfer characteristic. As a result, the GaN FET can bedriven either by a positive gate-to-source voltage (Vgs) or apositive gate-to-drain voltage (Vgd).The GaN FET from EPC Inc. is an enhancement modetransistor, whose output characteristics with differentgate-source voltages are shown in Fig. 2. For powerconversion applications, this characteristic increases safetybecause the device is off when the driving voltage is belowits threshold voltage. This decreases the designing difficultiesin power conversion systems.B. Characteristics of the GaN Schottky DiodeCompared with Si diodes, the GaN Schottky diode has alower forward voltage, as shown in Fig. 3. The GaN Schottkydiode exhibits a positive temperature coefficient because theforward voltage increases with an increase in temperature,while the Si diode shows a negative temperature coefficient.The GaN Schottky diode also has lower on-state losses. In-40-60-3-2.5-2-1.5-1-0.500.511.522.53Fig. 2. Electrical characteristics of GaN FET.Fig. 3. Forward characteristics of GaN Schottky diode(TPS3410PK 600V/6A).addition, the GaN Schottky diode has no minority carriers,which will greatly reduce transient voltage spikes.Furthermore, the GaN Schottky diode has a zero recoverycharge. Si diodes, taking a Si fast recovery epitaxial diodeDSEI12-06A as an example, typically have a 35ns recoverytime and their recovery charge is typically 0.5uC under thecondition of VR 50V, -diF/dt 200A/us, and IF 14A,T 100 C.III. TOPOLOGY ANALYSIS AND SIMULATIONRESULTS OF FLYBACK-FORWARD HIGHGAIN DC/DC CONVERTERSA. Operation Principe and Soft-switching Behavior ofFlyback-forward DC/DC ConvertersA flyback-forward high gain DC/DC converter is shownin Fig. 4 [16]-[18]. The main switches S1 and S2 work in theinterleaved mode, and their control signals have a 180 degreephase shift. The active-clamp circuits are mainly composedof auxiliary switches Sc1 and Sc2 and clamp capacitors Cc1 andCc2. The clamp switches Sc1 and Sc2 are drivencomplementarily by the main switches S1 and S2, which canrecycle the leakage energy, suppress the turn-off voltagespikes on the main switches, and realize ZVS for all of theprimary devices. In addition, there are two coupled inductors
86Journal of Power Electronics, Vol. 16, No. 1, January 2016in the converter L1 and L2, where the primary inductors L1aand L2a are coupled with the secondary inductors L1b and L2brespectively. Llk is the total leakage inductance, which isequivalent to the secondary side. The key waveforms andequivalent circuits in different operational stages are shownin Fig. 5 and 6, respectively. The operation processdescription is given in detail as follows.[t0-t1]: During this time, the main switches S1 and S2 are onand the two coupled inductors are charged by the inputvoltage in the flyback mode for energy storage. The auxiliaryswitches Sc1 and Sc2 are off. The output diodes Do1 and Do1 areboth reverse-biased, and the output capacitors Co1 and Co2provide energy to the load.[t1-t2]: At t1, the main switch S2 is turned off. Its parasiticcapacitor Cs2 is charged so that the drain–source voltage ofS2Vds2 increases. Since the GaN FET has a very small Cds, thevalue of Vds2 increases quickly.[t2-t3]: At t2, Vds2 increases and the voltage on the primaryinductor L2a decreases resulting in a corresponding decreasein the voltage on the secondary inductor L2b which makes theoutput diode Do1 conduct. During this time, the coupledinductor L1 operates in the forward mode and L2 works in theflyback mode to transfer energy to the load.[t3-t4]: At t3, the voltage on the parasitic capacitor Cs2increases to that on the clamp capacitor Cc2 which makes theequivalent antiparallel diode of the clamp switch Sc2 conduct.The coupled inductors L1 and L2 remain in the same mode as[t2-t3].[t4-t5]: At t4, the clamp switch Sc2 is turned on with ZVS.The current through the equivalent antiparallel diode of theclamp switch Sc2 transfers to Sc2 quickly.[t5-t6]: At t5, the clamp switch Sc2 is turned on. Due to theparasitic capacitor Cs2, Vds2 decreases linearly and that of theclamp switch Sc2 increases in an approximately linear way. Asa result, Sc2 turns off with ZVS. One part of the leakageenergy continues to be delivered to the load and another partof the leakage energy is recycled to the input source.[t6-t7]: At t6, Vds2 decreases to zero. Therefore, its equivalentantiparallel diode starts to conduct. The leakage current fallsdue to the voltage on the capacitor Co1.[t7-t8]: At t7, the main switch S2 turns on with ZVS. Thesecondary diode Do1 still conducts. At t8, the leakage currentdecreases to zero and the diode Do1 turns off with thezero-current switching operation. The two primary inductorsare again charged linearly by the input voltage.Fig. 4. Topology of flyback-forward high gain DC/DC converter.Fig. 5. Waveforms of flyback-forward high gain DC/DC converter.waveform of the drain-source voltage Vds of the mainswitches S1, S2 is shown in Fig. 7(b). The voltage and currentof S1 both without an active-clamp circuit and with anactive-clamp circuit are shown in Fig. 7(c) and Fig. 7(d)respectively. Compared with the simulation results, withoutan active-clamp, the circuit with an active-clamp achievesZVS turn on and ZCS turn off, which eliminates the voltagespikes of S1 and S2.B. Simulation of the flyback-forward DC/DC ConverterPSIM software is utilized to verify the operation principleof the circuit. The simulation parameters are listed as follows:Vin 25V, fs 100kHz, Vo 380V, and the resistive loadRo 722Ω.Waveforms of the primary side current IL1a, IL2a of thecoupled inductor, the secondary diode current IDo1, IDo2 andthe driving signal V gs1, Vgs2 are shown in Fig. 7(a). AIV. DEVICE SELECTION AND LOSS ANALYSIS OFTHE GAN FET BASED FLYBACK-FORWARDHIGH GAIN DC/DC CONVERTERThe design specifications of the GaN FET basedflyback-forward high gain DC/DC converter are shown inTable I.
87Loss Analysis and Soft-Switching Behavior TABLE IDESIGN SPECIFICATION OF FLYBACK-FORWARD HIGH GAIN DC/DCCONVERTERInput voltageOutput voltagePowerSwitch I220100-10IDo1IDo24204.974.970014.970024.97003Time 97(e)4.970014.970024.97003Time (s)(f)(b)gs110.50Is1(g)(h)Fig. 6. Equivalent circuits of flyback-forward DC/DC circuitoperational time intervals: (a) [t0-t1], (b) [t1-t2], (c) [t2-t3], (d)[t3-t4], (e) [t4-t5], (f) [t5-t6], (g) [t6-t7], and (h) [t7-t8].A.Device and Component Selection ofFlyback-forward High gain DC/DC ConvertertheFor a duty ratio of D 0.5, when Vin 40V, N 2.375 . Inthis case N 2. The main switch voltage is:VoutN 140VThe main switch current amplitude is:4.974.970014.970024.97003Time (s)(c)gs110.5The main switch is selected by the voltage levels and currentlevels [19]. The voltage gain is:Vout2N(1) Vin 1 DVds S Vds Sc Vin .970024.97003Time (s)(d)Fig. 7. Simulation waveforms of flyback-forward high gainDC/DC converter: (a) IL1a , IL2a , IDo1, IDo2, (b) Vds of S1and S2, (c)results without active-clamp, and (d) results with active-clamp.
88Journal of Power Electronics, Vol. 16, No. 1, January 2016I S1 PVin . min 10018 5.6 A(3)Therefore, two EPC2010 in parallel are employed as the mainswitches. Both the main and clamp switches have the samevoltage stress. Therefore, the parameters of the clamp switchesshould be the same as the main switches. EPC2010s areselected as the clamp switches.When the primary-side switch is turned off, the maximumvoltage drop of the rectified diodes is about 350V. The peakcurrent of the diodes is:I Do peak (( N VCc1 Vdc / 2) (1 D ) / f S ) / Llk(4)GaN Schottky diodes TPS3410PK 600V/6A produced byTransphorm Inc. are chosen as rectified diodes. The keyparameters are shown in detail as following: VF 1.3V, IR 25uA, Qc 54nC, and C 81pF.When coupled inductor turns ratio is N 2, the leakageinductance needs to satisfy the following condition:LLk 2 R0 N M N R0 (1 D )2 M 2 fsTABLE ПDESIGN SPECIFICATION OF A COUPLED INDUCTOR0.3mmCopper thickness0.9mmThickness of single board3mmWinding width0.2mmClearance between layers2Number of primary layers8Number of primary turns4Number of secondary layers16Number of secondary turnsiL1a (t ) I Lm1 NiLk (t ) I Lm1 NLm Vin D0.2 I Lm f SThe magnetizing inductor is chosen as Lm 43.75 H ,f s 100kHz , and the leakage inductance of the primary sideis LLk P 0.87 H .(t 3 t t 5 ) (8)[t5-t8]:iL1a (t ) I L1a (t5 ) NiLk (t ) I L1a (t5 ) N(5)(6)LLk(t t3 )where: V NVCc 2 Vo / 2 2V ， LLk 5 H .2The magnetizing inductor Lm can be determined by settingan acceptable current ripple, which is given by:( NVCc 2 Vo / 2)where: t5 t8 (t 5 t t 8 )Vot2 LLk(2*NVCc 2 Vo )Vo(9)*T2 .[t8-t9]: During this stage, the main switches S1 and S2 are inthe turn-on state. The current flowing through S1 is that of thecoupled inductor. According to the above analyses, the RMScurrent of S1 is given by:1 Ts(10)I L21a RMS iL1a 2 (t ) dtTs 0The two coupled inductors are composed of a planar EE coreEE32 with 3F3 material and printed circuit boards as windings.The main parameters of the two coupled inductors are the same,and are shown in Table П.When the RDS of EPC2010 is 18mΩ, the conduction loss ofS1 is:B. Loss Analysis of the flyback-forward High Gain DC/DCConverterPS1 of tf f sVpeak S1 I peak S1 / 6According to the symmetry of the circuit, switch S1 is takenas an example to make a loss analysis. Po 200W, Vin 25V,the conducting time of the main switch T1 D * TS , theclamp switches conducting time is T2 (1 D ) * TS , and thedead time is 1% of the switching period Ts.The active-clamp circuit leads to ZVS of S1, whose loss ismainly composed of conduction loss and switching loss.According to Fig. 5, during one switching period, the currentof S1 in every stage is:[t0-t3]: The current in one, which follows the primary of thecoupled inductor, is defined by:iL1a (t ) I Lm1P o2*Vin(7)[t3-t5]: Because of the effect of the active clamp circuit, theleakage current of the secondary ILk increases linearly.Converting this to the primary, the main switch current is:PS1 on I L1a RMS 2 * RDS / 2(11)The turn-off loss is:(12)where tf is the overlap time of IDS and VDS, and Vpeak S1 is thepeak voltage of the drain-source voltage.Since the clamp switch is turned on under ZVS, the currentflowing through the clamp switch can be expressed as:iSc1 (t ) I Lm1 NiLk (t ) I Lm1 N( NVCc 2 Vo / 2)LLk(t t3 )(t11 t t 13 ) (13)The RMS current of Sc1 is:I S2c 1 RMS 1Ts Ts0iSc1 2 (t ) dt(14)The active clamp switches are the same type as the mainswitches. Therefore, the conduction loss of Sc1 is:PSc1 on I S2c1 RMS* RDS(15)Turn-off loss of Sc1 is:PSc1 sw tf fsVpeak Sc1 I peak Sc1 / 6(16)
89Loss Analysis and Soft-Switching Behavior The current of the secondary side diode is in thediscontinuous current mode. As a result, the loss is mainlyconduction loss.[t3-t5]: The current increases linearly.iDo1 (t ) NVCc 2 Vo / 2LLk(t t3 ) (t 3 t t 5 )(17)[t5-t8]: The secondary-side current decreases linearly.Vo / 2(t t5 )LLk(18)iDo1 (t ) dt(19)iDo1 (t ) I Do1 peak The average current of Do1 is:I Do1 avg 1Ts Ts0TABLE ШPOWER LOSS OF GAN FET BASED FLYBACK-FORWARD HIGH GAINDC/DC CONVERTERConduction loss of S1Turn off loss of S1Conduction loss of Sc1Turn off loss of Sc1Conduction loss of Do1Loss of a coupled inductorDriving loss0.18W0.47W0.03W0.23W0.24W2.35W1WTABLE IVPOWER LOSS OF SI MOSFET BASED FLYBACK-FORWARD HIGHGAIN DC/DC CONVERTERConduction loss is:PDo1 on I Do1 avgVF(20)where VF is the forward voltage drop of the GaN Schottkydiode, which is 1.3V.The copper loss of a coupled inductor is estimated asfollows.22PCu p I rmsp Req I rms p * N p * l p * AspConduction loss of S1Turn off loss of S1Conduction loss of Sc1Turn off loss of Sc1Conduction loss of Do1Loss of a coupled inductorDriving loss0.2W2.2 W0.04W0.9W0.24W3.5W1.56W(21)where Irms p is the root mean square value of the primarycurrent; Np is the primary turns; lp is the mean path length ofthe primary coil; ρ is the resistivity of copper at 100 , whichis 2.266*10-6 Ω*cm; and Asp is the sectional area of theprimary conductor.The same method is used to estimate the copper loss ofsecondary side.Then, the core loss is PFe, which is given by:PFe PV *Ve(22)where PV is about 0.4W/cm3 for fs 100kHz, Bpk 0.2T, andVe 5.38cm3.The losses of the GaN FET based flyback-forward highgain DC/DC converter are shown in Table Ш. The totalcircuit loss is about 4.5W and the theoretical efficiency canreach 97.8%.The losses of the Si MOSFET based flyback-forward highgain DC/DC converter are shown in Table IV. The totalcircuit loss is about 8.64W and theoretical efficiency canreach 95.86%.V. EXPERIMENTAL RESULTS OF THE GAN FETBASED FLYBACK-FORWARD HIGH GAINDC/DC CONVERTERA. Experimental Comparison between the GaN FET andSi MOSFET Based on the flyback-Forward High GainDC/DC ConverterWhen an EPC2010 is applied into a flyback-forward highgain DC/DC converter, the prototype is shown in Fig. 8. Theunique Land Grid Array (LGA) package of EPC2010products, the parasitic parameters in the main power circuit,and the driver circuit can be significantly reduced. Thisimporves the driving stability, while reducing the voltagestress of the main switches.Experimental tests are conducted under the condition thatthe input voltage is 25V, the output power is 200W, the dutycycle of main switches is 0.74, and a GaN Schottky diodeTPS3410PK is applied. The obtained experimentalwaveforms are shown in Fig. 9(a), where channel 1 is theoutput voltage (100V/div), channel 3 is Vds of the mainswitches S1 (50V/div), and channel 4 is the primary current ofthe coupled inductors IL1a (5A/div). The temperatures of thedevices are tested at a 30 C room temperature, as shown inthe Fig. 9(b), where the hotter part is around main switchesEPC2010s.Fig. 10 shows the experimental results when the mainswitch is selected as a Si MOSFET IPB107N20N3G200V/88A under the same operating conditions.Experimental tests are conducted under the condition that theinput voltage is 25V and the output voltage is 380V. Only themain switches and the driver are changed.In Fig. 10(a), channels 1 and 2 are Vds of the main switchesS1 and S2 (50V/div), channel 4 is the primary current of thecoupled inductors IL1a (10A/div), and channel 3 is the outputvoltage (100V/div). The temperatures of the devices weretested at a 30 C room temperature, as shown in the Fig. 10(b),where the hotter part is around main switchesIPB107N20N3G.From the Fig. 9(a), it can be concluded that there is novoltage spikes when the main switch S1 is turned off, and thatswitching loss of the GaN FET is small. The output DCvoltage of the circuit can be stabilized at 380V. On the otherhand, there is a visible voltage spikes of the Si MOSFET
90Journal of Power Electronics, Vol. 16, No. 1, January 2016Vds1(50V/div)Vo(100V/div)IL1a(5A/div)Fig. 8. PCB board of GaN FET based flyback-forward high gainDC/DC Converter.(a)Vo(100V/div)VDo1(100V/div)I Do1(2A/div)(a)(b)Fig. 11. Test results of GaN FET based flyback-forward high gainDC/DC converter applying GaN diodes: (a) experimentalwaveforms and (b) thermal test results of TPS3410PK.VDo1(100V/div)IDo1(2A/div)(b)Fig. 9. Test results of GaN FET based flyback-forward high gainDC/DC converter (a) experimental waveforms, (b) thermal testresults.(a)V ds1(50V/div)V ds2(50V/div)V o(100V/div)IL1a(10A/div)(a)(b)Fig. 10. Test results of Si MOSFET flyback-forward high gainDC/DC converter: (a) experimental waveforms and (b) thermaltest results.(b)Fig. 12. Test results of GaN FET based flyback-forward high gainDC/DC converter applying Si diodes: (a) experimental waveformsand (b) thermal test results of DSEI12-06A.based flyback-forward high gain DC/DC Converter, whichresults in a decreased efficiency. The temperature of the SiMOSFET is higher than that of the GaN FET under the sameoperating conditions.The highest efficiency is 95.8% at the 200W power pointof the GaN FET based flyback-forward high gain DC/DCconverter. Meanwhile, it is only 94% at the 200W powerpoint of the Si MOSFET based converter. From theexperimental results, it can be seen that the application of the
91Loss Analysis and Soft-Switching Behavior GaN device can reduce the voltage stress of the switches andincrease the circuit efficiency.B. Experimental Comparison between the GaN Diode andthe Si Diode Based on a Flyback-Forward High GainDC/DC ConverterBased on a flyback-forward high gain DC-DC converterapplying a EPC2010, an experimental comparison betweenthe GaN diode and the Si diode with the same 600V voltagelevel is made to determine the advantages of the GaN diode.Experimental tests are conducted under the condition thatthe input voltage is 25V, the output power is 200W, the dutycycle of the main switches is 0.74, and GaN Schottky diodesTPS3410PK are applied. The obtained experimentalwaveforms are shown in Fig. 11(a), where channel 1 is thecurrent of Do1 IDo1(2A/div), and channel 4 is the forwardvoltage of Do1VDo1(100V/div). Fig. 11(b) shows thetemperature test results of the TPS3410PK at a 30 C roomtemperature, where highest temperature is 51.1 C.Under the same conditions, Si fast recovery epitaxialdiodes DSEI12-06A manufactured by IXYS are applied tothe converter for comparative purposes. The results areshown in Fig. 12(a), where channel 2 is the forward voltageof Do1 VDo1(100V/div), and channel 3 is the current of Do1IDo1(2A/div). Fig. 12(b) shows temperature test results of theDSEI12-06A at a 30 C room temperature, where highesttemperature is 64.8 C.From Fig. 11(a), it can be concluded that there is littlereverse recovery current when the diode is turned off and itverifies the zero recovery charge. Meanwhile from Fig. 12(a),a larger reverse recovery current appears compared with Fig.11(a). In addition, the voltage spike is larger than that shownin Fig. 11(a) during reverse recovery time, which reducesefficiency. Comparing Fig. 11(b) and Fig. 12(b), it can beseen that the Si diode has a higher temperature under thesame operating conditions as the GaN diode. This indicates alarger [12]VI. CONCLUSIONThis paper describes the development of a GaN FET andpresents its structure and electrical properties. A GaN FETmanufactured by EPC Inc. is applied in a flyback-forward highgain DC/DC converter. A loss analysis is discussed in detail forthe GaN FET based flyback-forward high gain DC-DCconverter. The application of the GaN FET can significantlyreduce the switch off voltage spike, and reduce switchinglosses. An experimental comparison between a GaN diode anda Si diode is made to determine the advantages of the GaNdiode. Finally, a 200W GaN FET based flyback-forward highgain DC/DC converter is established. Experimental resultsverify that the GaN FET is superior to the Si MOSFET, andthat the GaN Schottky diode is superior to the Si fast recoveryepitaxial diode at the same voltage level.[13][14][15][16]A. Lidow, J. Strydom, M. Rooij, and Y. Ma, GaN transistorsfor efficient power conversion, Power ConversionPublications, 2nd, 2012.K. S. Boutros, R. Chu, and B. Hughes, “Gan powerelectronics for automotive application,” Energytech, pp.1-4,2012.T. Morita, S. Tamura, Y. Anda, M. Ishida, Y. Uemoto, T.Ueda, T. Tanaka, and D. Ueda. “99.3gan-based gateinjection transistors,” Applied Power Electronics Conferenceand Exposition (APEC), pp.481-484, 2011.S. Tamura, Y. Anda, M. Ishida, Y. Uemoto, T. Ueda, T.Tanaka, and D. Ueda, “Recent advances in gan powerswitching devices,” Compound Semiconductor IntegratedCircuit Symposium(CSICS), pp.1-4, Oct. 2010.M. J. Scott, J. Li, and J. Wang, “Applications of GalliumNitride in power electronics,” Power and Energy Conferenceat Illinois(PECI), pp. 1-7, Feb. 2013.M. J. Scott, K. Zou, E. Inoa, R. Duarte, Y. Huang, and J.Wang, “A Gallium Nitride switched-capacitor powerinverter for photovoltaic applications,” Applied PowerElectronics Conference and Exposition(APEC), pp.46-52,Feb. 2012.M. J. Scott, K. Zou, J. Wang, C. Chen, M. Su, and L. Chen,“A Gallium Nitride Switched-Capacitor Circuit UsingSynchronous Rectification,” IEEE Trans. Ind. Appl., Vol. 49,No. 3, pp.1383-1391, May/Jun. 2013.J. Delaine, P. O. Jeannin, D. Frey, and K. Guepratte,“Improvement of GaN transistors working conditions toincrease efficiency of A 100W DC-DC converter,” AppliedPower Electronics Conference and Exposition(APEC), pp.656-663, Mar. 2013.X. Ren, D. Reusch, S. Ji, Z. Zhang, M. Mu, and F. C. Lee,“Three-level driving method for GaN power transistor insynchronous buck converter,” Energy Conversion Congressand Exposition(ECCE), pp.2949-2953, Sep. 2012.D. Reusch , F. C. Lee , D. Gilham , and Y. Su, “Optimizationof a high density gallium nitride based non-isolated point ofload module,” Energy Conversion Congress andExposition(ECCE), pp.2914-2920, Sep. 2012.S. Ji, D. Reusch, and F. C. Lee, “High-Frequency HighPower Density 3-D Integrated Gallium-Nitride-Based Pointof Load Module Design,” IEEE Trans. Power Electron., Vol.28, No. 9, pp. 4216-4226, Sep. 2013.F. C. Lee and Q. Li, “High-Frequency IntegratedPoint-of-Load Converters: Overview,” IEEE Trans. PowerElectron., Vol. 28, No. 9, pp. 4127-4136, Sep. 2013.S. Ji, D. Reusch, and F. C. Lee, “High-Frequency HighPower Density 3-D Integrated Gallium-Nitride-Based Pointof Load Module Design,” IEEE Trans. Power Electron., Vol.28, No. 9, pp. 4216-4226, Sep. 2013.X. Zhang, C. Yao, M. J. Scott, E. Davidson, J. Li, P. Xu, andJ. Wang, “A GaN Transistor based 90 W IsolatedQuasi-Switched-Capacitor DC/DC Converter for AC/DCAdapters,” IEEE Workshop on Wide Bandgap PowerDevices and Applications(WiPDA), pp. 15-12, Oct. 2013.X. Zhang, C. Yao., X. Lu, E. Davidson, M. Sievers, M. J.Scott, P. Xu, and J. Wang, “A GaN Transistor based 90WAC/DC Adapter with a Buck-PFC Stage and an IsolatedQuasi-Switched-Capacitor DC/DC Stage,” Applied PowerElectronics Conference and Exposition(APEC), pp. 109-116,Mar. 2014.J. H. Lee, J. H. Park, and H. Jeon, “Series-connectedforward-flyback converter for high step-up power
92Journal of Power Electronics, Vol. 16, No. 1, January 2016conversion,” IEEE Trans. Power Electron., Vol. 26, No. 12,pp. 3629-3641, Dec. 2011.[17] W. Li, P. Li, H. Yang, and X. He, “Three-level forward–flyback phase-shift zvs converter with integratedseries-connected coupled inductors,” IEEE Trans. PowerElectron., Vol. 27, No. 6, pp. 2846-2856, Jun. 2012.[18] D.-H. Kim, J.-H. Jang, J.-H. Park, and J.-W. Kim,“Single-ended high-efficiency step-up converter using theisolated switched-capacitor cell,” Journal of PowerElectronics, Vol. 13, No. 5, pp.766-778, 2013.[19] J.-M. Kwon, E.-H. Kim, B.-H. Kwon, K.-H. Nam,“High-efficiency fuel cell power conditioning system withinput current ripple reduction,” IEEE Trans. Ind. Electron.,Vol. 56, No. 3, pp. 826-834, Mar. 2009.Yan Li was born in Heilongjiang Province,China, in 1977. She received her B.S. andM.S. degrees in Electrical Engineering fromYanshan University, Qinhuangdao, China, in1999 and 2003, respectively; and her Ph.D.degree in Electrical Engineering from theNanjing University of Aeronautics andAstronautics, Nanjing, China, in 2009. From1999 to 2009, she was at Yanshan University. Since 2009, shehas been in the School of Electrical Engineering, BeijingJiaotong University, Beijing, China. Her current researchinterests include multiple-input dc/dc converters, renewablepower systems, and PV grid-tied systems.Trillion Q. Zheng (Qionglin Zheng)(M’06-SM’07) was born in Jiangshan,Zhejiang Province, China, in 1964. Hereceived his B.S. degree in ElectricalEngineering from Southwest JiaotongUniversity, Sichuan, China, in 1986; and hisM.S. and Ph.D. degrees in , Beijing, China, in 1992 and 2002, respectively. He ispresently a Distinguished Professor at Beijing JiaotongUniversity. He directs the Center for Electric Traction, foundedby Ministry of Education, China. His current research interestsinclude the power supplies and AC drives of railway tractionsystems, hig
GAIN DC/DC CONVERTERS A. Operation Principe and Soft-switching Behavior of Flyback-forward DC/DC Converters A flyback-forward high gain DC/DC converter is shown in Fig. 4 [16]-[18]. The main switches S1 and S2 work in the interleaved mode, and their control signals have a 180 degree phase shift. The active-clamp circuits are mainly composed
switch". The goal of "soft switch" is to develop a standard PWM switch cell with built-in adaptive soft switching capabilities. Just like a regular switch, only one PWM signal is needed to drive the soft switch under soft switching condition. The core technique in soft switch development is a built-in adaptive soft switching circuit with
Pearl Green 455 Pearl Blue 465 Orange Pearl 470 Dark Blue 475 Garnet 480 Gold 801 Soft Lilac 802 Soft Yellow 803 Soft Orange 804 Soft Garnet 805 Soft Dark Blue 806 Soft Light Blue 807 Soft Pastel Green 808 Soft Pistachio Green 809 Soft Grey 810 Soft Black 128 Dental White 400 Yellow 405 Lilac 425 Silver Grey 435 Pearl
Soft Speech Booster Soft Speech Booster is a feature of VAC that provides increased level of soft gain at high frequencies. The feature en-hances the details of soft speech signals and is adapted to client’s individual needs and preferences for soft sounds and soft speech. The new Soft Sound Perception trimmer in Genie adjusts how the soft
Altistart 48 soft start - soft stop units The Altistart 48 soft start - soft stop unit is a controller with 6 thyristors which is used for the torque-controlled soft starting and stopping of three-phase squirrel cage asyn
SPEEDFAX YET Remove IP20 info Added software to pg . Revised on 01/06/20. 7/2 Smart Infrastructure, Industrial Control Catalog 2021 7 SOFT STARTERS Soft Starters Introduction 6/2 Siemens IC 10 · 2020 Switching Devices – Soft Starters and Solid-State Switching Devices Introduction 6 . Industrial Control Catalog 2021 7/3 7 SOFT STARTERS .
"switch" or other logic element) specifically for soft robots. We have directly integrated unidirectional, soft check valves into a soft robot to vent the combustion products of an explosion, which powered the soft robot (22). Wehner et al.(23) developed an entirely soft, autonomous
TUBE BENDER TUBE BENDER Maxi TUBE BENDER Maxi MSR Method: Manual 90 Manual 90 Manual 90 Working range: Copper 1 mm, soft 1 mm, soft Working range: Aluminium 1 mm, soft 1 mm, soft Working range: Precision steel 1 mm, soft 1 mm, soft Working range: Stainless steel 1 mm, soft Working range: MSR2 mm 2 mm Page56 57 58 Bending System Overview .
9 Variable Timing Soft Switching over a Wide Load Current Range During turn-off, VCE slowly rises after IC drops to zero Variable timing achieves soft-switching at all current conditions Bonus - slow dv/dt that will result in low EMI emission During turn-on, current IC rises after voltage VCE drops to zero-100 0 100 200 300 400 500 12 3456-100 0 100 200
