双向DC-DC变换器软开关(完整版)实用资料.doc

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1、双向DC-DC变换器软开关（完整版）实用资料(可以直接使用，可编辑 完整版实用资料，欢迎下载）A New ZVS Bidirectional DC-DC Converter WithPhase-Shift Plus PWM Control SchemeHuafeng Xiao, Liang Guo, Shaojun XieCollege of Automation Engineering,Nanjing University of Aeronautics and AstronauticsNanjing, 210016, ChinaAbstract-The current-voltage-fed

2、 b i d i rect ional DC-DC converter can reali ze ZVS for the swi tches wi th the use of the phase-sh ft (PS technology, however the current-fed sw tches suffer from hi gh voltage spi ke and hi gh ci rculati ng conducti on losses. In order to solve these problems, a novel phase-shift plus PWM (PSP co

3、ntrol ZVS b -d rect onal DC-DC converter s proposed, wh i ch adopts act i ve clamp i ng branch and PWM technology. The novel converter can reali ze ZVS for all power swi tches from no load to full load. The operati on pri nci ple i s analyzed and verified by a 28V/270V conversion prototype rated at

4、1.5kW.I. I NTRODUCTION In recent years, the development of high power isolated bidirectional dc-dc converters (BDC has become an important topic because of the requirements of electric vehicle, uninterruptible power supply (UPS and aviation power system 1-7. In a typical UPS system, the battery is c

5、hargedwhen the main power source is normal and the batterydischarges to supply power in the event of lose of main power source. In the aircraft high voltage direct current (HVDC power supply system, when the 270V HVDC generator is ingear, it charges the 28V battery and supplies the 28V key loadby th

6、e BDC, and when the generator is in failure, the 28V battery discharges to supply 270V key load by the BDC. Thehigh-low voltage conversion and electrical isolation are necessary in above-mentioned condition. The current-voltage-fed BDC is fit for such system due to it has ahigh voltage conversion ra

7、tio and low current ripple.A dual active full bridge dc-dc converter was proposed forhigh power BDC 4, 5, which employs two voltage-fed inverters to drive each sides of a transformer. Its symmetric structure enables the bidirectional power flow and ZVS for allswitches. A dual active half bridge curr

8、ent-voltage-fed soft-switching bidirectional dc-dc converter was proposed with reduced power components 6, however, the current-fedhalf bridge suffers from a high voltage spike because of theleakage inductance of the transformer. When the voltage amplitude of the two sides of the transformer is not

9、matched,the current stresses and circulating conduction losses becomehigher in 4, 5, and 6. In addition, these converters can notachieve ZVS in low-load condition. These disadvantagesmake it not suitable for large variation of input or outputvoltage condition. An asymmetry bidirectional dc-dcconvert

10、er with Phase shift plus PWM (PSP control wasproposed in 7, the circulating conduction losse is reduced,however, it results a current bias which decreases the utilization of the transformer.A current-voltage-fed PSP ZVS BDC based on an isolated dual boost converter and a half bridge converter is pro

11、posed, as shown in Fig.1 (a. The converter with an active clamping branch Sa1, Sa2 and Cc avoids the voltage spike, achieves ZVS of S1 and S2, and also restrains the start-inrush current 8. By PWM control of S1 and S2, Vab and Vcd are well matched, which reduces circulating conduction losses, also r

12、ealizes ZVS from no load to full load. The decoupling controlof Phase-shift (PS and PWM is realized by two independenceclose-loops control circuits. The operation principle is analyzed in detail. A 22-32V / 270V 1.5kW prototype is built to verify the operation principle of the proposed converter. II

13、. O PERATION P RINCIPLEThe BDC has two operation modes, the energy flowing from V 1 side to V 2 side is defined as Boost mode, and the counterpart is defined as Buck mode. Before the analysis, the following assumptions are given: 1 All the active power devices are ideal switches with parallel body d

14、iodes and parasitic capacitors, 2 The inductance L 1 and L 2 are largeenough to be treated as two current sources with value of 0.5I 1, 3 The transformer T is ideal one with series leakage inductor L r . Fig.1 (b shows the key waveforms in the Boost mode. Onecomplete switching cycle can be divided i

15、nto ten periods. Because of the similarity, only a half switching cycle is described in detail. The equivalent circuits are shown in Fig.2. Because the two sides of the topology are symmetrical, the operation principles in Buck mode are similar to those inBoost mode. Fig.1 (c shows the key waveforms

16、 in the Buck mode.1 Stage0 Before t 0: Refer to Fig.2 (a. S 1, S a2 and S 4 are conducting. The current of the leakage inductor L r is i L r =-I (0. The power flows from V 1 side to V 2 side. 2 Stage1 t 0, t 1: Refer to Fig.2 (b. At t 0, S a2 is turned off. L r , C 2 and C a2 begin to resonant, C 2

17、is discharged and C a2 is charged. 3 Stage 2 t 1, t 2: Refer to Fig.2 (c. At t 1, the voltage across C 2 attempts to overshoot the negative rail. D 2 is therefore forward biased. During this period, S 2 can be turned on at zero voltage. The voltage across C a2 is clamped at V Cc . The current of the

18、 leakage inductor L r is (r221r 20L n V n I i L +=. (a (b (cFig. 1. The novel PSP ZVS BDC (a Main circuit. (b Key waveforms in the Boost mode. (c Key waveforms in the Buck mode.4 Stage3t2, t3: Refer to Fig.2 (d. At t2, S1 is turned off. L r, C1 and C a1 begin to resonant, C1 is charged, C a1 is disc

19、harged. The current of L r is (aStage 0 before t0 (bStage 1t0 , t1 (c Stage 2t1 , t2 (d Stage 3t2 , t3 (eStage 4t3 , t4 (f Stage 5t4 , t5Fig. 2. Equivalent circuits of switching stages in the Boost mode.(r221r221r12212LndVnLndVnIi L+=.5 Stage4t3, t4: Refer to Fig.2 (e. At t3, the voltage across C a1

20、 attempts to overshoot the negative rail. D a1 is therefore forward biased. During this period, S a1 can be turned on at zero voltage. The voltage across C 1 is clamped at V Cc . The current of L r rises to a positive value. 6 Stage 5 t 4, t 5: Refer to Fig.2 (f. At t 4, the current of L r is positi

21、ve. D 3 turns on. During this period, S 3 can be turned on at zero voltage. The current of L r is i L r =I (0. The power flows from V 1 side to V 2 side. At t 5, starting the second half cycle, which is similar to the first half cycle.III. C HARACTERISTICS O F T HE N OVEL BDCA. Output PowerThe phase

22、 shift angle (5.05.0 between V ab and V cd , which is defined to be positive when V ab is leading to V cd in phase, is used to control magnitude and the direction of the transmitted power. The pulse width d of S 1 and S 2 is used to match V ab and V cd , means that the current i L r keeps horizontal

23、 in stage 0 and stage 5. The duty cycle of S 1 and S 2 are 211221V n Vn d = (1 Under PS control, the output power is(L n V V n P r 222211= (2 Under PSP control, the output power is(+=,1d 2,2d 1d 21d 2,0,5.0d d 1220,d 12,21d 2d 1d 12d 12,5.1d d 122222212B. Circulating CurrentWhen transmitted power is

24、 P N , the current RMS of L r is(i I L 2d 202r RMS =(4Fig. 3. Curves of the output power versus the phase-shift angle.(r L n V n 222122pu=, V 1=2232VFig. 4. The RMS value of i L r . (V 1=2232V , V 2=270V , n 2:n 1=2.1,P N =1.5kW, f =100kH Z , L r =1.2HFig.4 shows the comparing of the current RMS of

25、L r under PS control and PSP control. In evidence, the circulating current is less under PSP control.C. Range for Achieving Soft SwitchingFrom the section II , it can be known that in order to achieve ZVS for all switches, equation (5 should be satisfied in Boost mode0(0r 313r 121r t i t i t i t i t

26、 i L L L L L (6 This converter can satisfy (5 or (6 well from no load to full load under PSP control. In other words, compared with the PS control, the PSP control can expand the ZVS range.IV. C ONTROL S TRATEGY Fig. 5. Control scheme. (a (b(c(dFig.6. Experimental waveforms at V 1=32V and V 1=22V .

27、(a PSP control at V 1=32V . (b PS control at V 1=32V . (c PSP control at V 1=22V . (d PS control at V 1=22V .The decoupling control of phase-shift angle and duty cycle d is realized with two independence close-loop circuits, as shown in Fig.5. The phase-shift angle close-loop circuit adopts one port

28、 voltage (V 2 regulated and another port (the battery port, V 1 current regulated to realize the energy bidirectional transmitted freely. The duty cycle close-loop circuit realizes the matching of V ab and V cd when V 1 is variation.V. E XPERIMENTAL R ESULTS A ND D ISCUSSIONS In order to verify the

29、operation of the proposed converter, a 1.5kW prototype was built in laboratory.1 The battery voltage of V 1 side: V 1=22-32VDC. 2 The rated voltage of V 2 side: V 2=270VDC. 3 Rated power: P N =1.5kW. 4 The turns ratio of the transformer: n 2:n 1=2.1. 5 The leakage inductor of the transformer: L r =1

30、.2H. 6 The inductors: L 1=L 2=15H. 7 The clamping capacitor: C c =3F. 8 The capacitors: Ca=Cb=470F. 9 Switches S1 and S2: APT20M11JFLL. 10 Switches S3 and S4: APT77N60JC3. 11 Switches Sa1 and Sa2: APT20M16LFLL.(a (b (cFig. 7. Gate drive signal, the voltage across the drain and source, and the drain

31、current of the switches at full load and V1=30V in Boost mode. (a S1. (b S3.(c S a1.12 Switching frequency: fs =100kHz.Fig.6 (a and (b show the experimental waveforms of the leakage inductor current i L r, the primary voltage v ab, and the secondary voltage v cd at V1=32V in Boost mode with 1.5kW ou

32、tput power under PSP and PS control respectively. Since the voltage V1 and voltage V2 are match in this case, the maximum current of L r under PSP control and PS control is the same. Fig.6 (c and (d show the experimental waveforms of the leakage inductor current i L r, the primary voltage v ab, and

33、the secondary voltage v cd at V1=22V in Boost mode with 300W output power under PSP control and PS control. In this case, voltage V1 and voltage V2 are not matched. Therefore,(a (b (cFig. 8. Gate drive signal, the voltage across the drain and source, and the drain current of the switches at full loa

34、d and V2=300V in Buck mode. (a S1. (b S3.(c S a1.the current stress of L r with PS control is higher than that of PSP control.Fig.7 (a, (b and (c show the gate drive signal, voltage across the drain and source, and the drain current of S1, S3 and S a1 respectively, at V1=30V in Boost mode with 1.5kW

35、 output power under PSP control. Fig.8 (a, (b and (c show the gate drive signal, voltage across the drain and source, and the drain current of S1, S3 and S a1, respectively, at V2=300V and I1=-45A in Buck mode with 1.5kW output power under PSP control. Fig.7 and Fig.8 illustrate that all the switche

36、s realize ZVS. The experimental results are in agreement with the theoretical analysis well. Fig. 9. Waveform of the energy bidirectional Transmitted. there are voltage v2 and current i1. When the voltage on V2 port is higher than the reference value, the bidirectional dc-dc converter charges the ba

37、ttery. When the voltage on V2 port drops, the battery turns to discharge and maintains the v2 voltage as 270VDC. The experimental results convinced that the novel control strategy can control the energy conversion freely. The respond time of voltage rebuilding is 10ms. Therefore, this converter has

38、the high steady and dynamic performance. Fig.10 (a shows the overall efficiency curves at different load and V1 voltage under PSP control. Fig.10 (b shows the efficiency curves of the converter under PSP control and PS control. It can be easily find that PSP control has higher efficiency than PS con

39、trol, especially in low battery voltage. VI. CONCLUSION This paper proposed an novel ZVS bidirectional dc-dc converter with PS plus PWM control, which has the following advantages: 1 The converter avoids the voltage spike with the use of an active clamping branch Sa1, Sa2 and Cc. 2 The PS plus PWM c

40、ontrol reduces circulating current and expands the ZVS range. 3 The decoupling control realizes the energy conversion freely, which has the high steady and dynamic performance. (a 1 2 3 4 5 6 (b Fig.10 Conversion efficiency. (a The efficiency in different output power and V1 voltage under PSP contro

41、l. (b The efficiency in Boost mode under PSP control. 7 8 REFERENCES Fanghua Zhang, Lan Xiao, and Yangguang Yan, “Bi-directional forward-flyback DC-DC converters,” IEEE PESC04, 20-25 Jun., 2004:4058-4061. Lizhi Zhu, “A novel soft-commutating isolated boost full-bridge ZVS-PWM dc-dc converter for bid

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