activepowerdecouplingcontrolfor single ...pe.csu.edu.cn/lunwen/122-active power decoupling control...

0278-0046 (c) 2020 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TIE.2020.2984981, IEEETransactions on Industrial Electronics

IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS

Abstract—The ripple power with double grid frequency

inherently exists in single-phase current source rectifier.To achieve the constant DC-link current, an alternative wayis to use an LC resonator tuned at 100 Hz to block theripple power. However, this method requires large passivecomponents, which will degrade the power density andeven the reliability. What’s worse, the decouplingperformance will be deteriorated when the parameter driftshappen. In this letter, a control strategy based onemulating the output voltage characteristic of the LCresonator is proposed. Then, the decoupling function asthe same with using a real LC resonator is achieved. At thesame time, no bulky passive components are needed andthe issue caused by parameter drifts is also avoided. Inaddition, the modular design of the LC emulator can beachieved. A prototype was built to verify the effectivenessof the proposed method.

Index Terms—Active power decoupling, LC resonator,ripple power, single-phase current source rectifier.

I. INTRODUCTIONC/DC converters are nowadays widely used in powerelectronics systems [1]. However, the instantaneous

power of the single-phase source pulsates with two times of theAC source frequency [2, 3]. Then, a strong voltage/currentharmonic (voltage harmonic in current source converter (CSC)and current harmonic in voltage source converter (VSC))appears on the converter DC-link, causing a pulsation at twicethe grid frequency. This low frequency component is oftenundesirable since it causes various problems depending on theapplications [2, 3]. Addressing this issue, the DC-linkinductance/capacitance must have sufficient large value toobtain the constant DC current/voltage. However, the passive

Manuscript received December 10, 2019; revised February 14, 2020;accepted March 23, 2020. This work was supported in part by theNational Natural Science Foundation of China under Grant 51677195,Grant 61933011 and Grant 61903381. (Corresponding author: JianhengLin.)

Y. Liu, W. Zhang, J. Lin, and M. Su are with the School of Automation,Central South University, Changsha 410083, China (e-mail:[email protected]; [email protected]; [email protected];[email protected]).

X. Liang is with Department of Civil, Structural and EnvironmentalEngineering, University at Buffalo, The State University of New York,New York, USA (e-mail:[email protected]).

components with large values will disturb the size reduction,slow down the system dynamic.

To reduce the size of the low-frequency inductor/capacitorrequired, an LC tank circuit (parallel resonance circuit in CSCand series resonance circuit in VSC) is added to be in series (inCSC) or parallel (in VSC) with the DC side of the converter[4-8]. The function of the LC tank circuit is to generate an ACvoltage (AC current) to compensate the pulsating component.This method has found wide applications in PV [4], fuel cells[5], LED drivers [6], and so on. However, the resonant tank isfound to result in the sensitivity to the distortion in the gridvoltage and the possibility of oscillation with realistic grid sideinductances. A possible solution of using a current-ripplefeedback is proposed in [7] to eliminate this instability. Besides,the added LC tank circuit increases the order of the system andaffects the DC link dynamics. Literature [8] provides acomprehensive analysis of that considering the LC resonantfilter and proposed a partial state feedback control to improvethe system performance. Although the total values of thepassive components are reduced by employing the LCresonator, the size is still large as a result of low resonantfrequency. Another drawback is that the resonant frequencywill be changed when the LC parameters drift. Then, thereexists residual ripple power flowing into the DC-link side andthe decoupling performance is degraded.

In this letter, an active power decoupling control method isproposed for a single-phase CSC. An electric circuit is insertedto the DC-link to emulate the external voltage characteristic ofa parallel LC tank circuit. Then the same function as a real LCtank circuit can be achieved. In addition, no bulky passivecomponents are used (only small inductors and film capacitorsare needed). Therefore, the power density and the reliability canbe improved dramatically. Moreover, the modular design canbe achieved because the decoupling control of the emulatoronly needs the extra information of the DC-link current.

II. PASSIVE POWER DECOUPLING METHOD USING AN LCRESONANT CIRCUIT

For CSC, the DC side voltage is low, which makes it suitablefor the applications of electric vehicle charging, light-emittingdiode (LED), photovoltaic (PV) system, and fuel cells system[3, 4]. Fig. 1 shows the circuit structure of the current sourcerectifier. The inductor Lg and capacitor Cg at the AC sidecomprise an LC low pass filter, helping shape the choppingcurrent irec into a sinusoidal wave. Ldc is the inductor in the DC

Active Power Decoupling Control forSingle-Phase Current Source RectifierBased on Emulating LC Resonator

Yonglu Liu, Member, IEEE, Wanlu Zhang, Jianheng Lin, Mei Su and Xiao Liang

A

Authorized licensed use limited to: Central South University. Downloaded on April 30,2020 at 08:17:26 UTC from IEEE Xplore. Restrictions apply.




Fig. 1. Single-phase current-type rectifier.

Fig. 2. Single-phase current-type rectifier with an LC resonator.

side and RL denotes the load resistance. Considering the unityinput power factor, the input voltage and current are given as

cos( )cos( )

g m g

g m g

u U ti I t

(1)

where ωg=2πfg (fg is the grid frequency) and Um, Im are theamplitudes of ug, ig respectively. The instantaneous power pin inthe input side is then expressed as

/ 2 cos(2 ) / 2in g g m m m m g

p p

p u i U I U I t

(2)

which contains a DC component ( p ) and an AC component ( p~ )with a secondary pulsation. According to power conservation,the output voltage of the rectifier can be expressed as

// (2 ) cos(2 ) / (2 )r

r in dc

m m dc m m g dc

rU u

u p iU I i U I t i

. (3)

The dynamic differential equation of the DC side is establishedas follow:

/ (2 ) cos(2 ) / (2 )

dcdc r dc L

m m dc m m g dc dc L

diL u i Rdt

U I i U I t i i R

. (4)

With the assumed initial condition idc(t=0)=0, idc is solved as

2 2 2 2

2 2 2

2 /2 2 2

2 2 2

0.5 [ cos(2 ) sin (2 )]

( )

0.5 ( 2 )

( )

( )m m L g L dc g dc L g g

L L dc gR t LL dc

m m dc g L

L L dc g

dcU I R t R L L R t

R R L

U I L R e

R R L

i t a b

a

b

. (5)

Obviously idc contains an unexpected secondary pulsatingcomponent in steady-state.

To address this issue, an intuitive method is to employ a largeDC inductor Ldc to smooth the DC-link current. Buttheoretically it can remain constant only when Ldc is infinite,and the large inductor will decay the power densitysignificantly and make the dynamic response dull.

Alternatively, an LC parallel resonator, whose resonant

Fig. 3. Relationship between the capacitance and the inductance using in thephysical LC resonator.

frequency is tuned at twice of the grid frequency (ωr=2ωg), isanother feasible solution, as shown in Fig. 2. The equivalentimpedance of the parallel LC resonator is

21

1d

d dd d d

j LZ j Lj C L C

. (6)

For the DC component in ur, Zd is equal to zero and theresonator can be viewed as short-circuit. While, for the ACcomponent, when Ld and Cd suffice

1 /r d dL C (7)Zd is equal to infinite and the resonator can be viewed asopen-circuit. Then, the low frequency ripple voltage isprevented from entering the DC side. From the view ofvolt-second balance, the function of the LC resonator is togenerate a voltage that is reversed with ru~ . Then, the DC-linkinductor is exempt from the secondary ripple voltage.The relationship between the capacitance and the inductancewhen satisfying (7) is depicted in Fig. 3. Actually, if Cddiminishes to zero, Ld should be infinite, which is the case ofemploying an infinite large inductor Ldc. The method byemploying the parallel LC resonator is easy to accomplish, butseveral defects also exist. Due to the low resonant frequency 2fg(100 Hz), passive components with large volume areunavoidably used. For instance, if Ld takes 2.5 mH, Cd needs1000 μF, resulting in low power density. What’s worse, thedecoupling performance will deteriorate due to the tolerance orparameter drifts. To overcome these disadvantages, an activemethod of using electric circuits to emulate the outputcharacteristic of the LC resonator is proposed in this letter.

III. PROPOSED POWER DECOUPLING CONTROL

A. Basic IdeaIn Fig. 2, the dynamics equation of uab can be expressed as

2 2/( ) ( )d

ab dcr

s Cu s i ss

. (8)

In order to achieve the same external voltage characteristic ofthe LC resonator, an extra electric circuit is employed and itsoutput voltage reference is designed as

*_ 2 2( ) ( )r

ab r dcr

k su s i ss

(9)

where kr is the adjustable resonant gain.





Fig. 4. Feasible circuits to emulate the LC resonator. (a) Asymmetric H-bridgecircuit. (b) H-bridge circuit.

Fig. 5. Block diagram of the control scheme.

In the ideal condition, the LC resonator only buffers theripple power (reactive power) and will not consume power.However, to stabilize the capacitor voltage in the electric circuit,a resistance Rd is virtualized to achieve voltage regulation. Rd>0(Rd<0) denotes that the circuit absorbs power (releases power).Accordingly, the ultimate injected voltage reference ismodified to

*

*2 2( ) ( )

d

rab d dc

r

Z

k su s R i ss

. (10)

B. Circuit RealizationSeveral feasible circuits to emulate the physical LC resonator

are shown in Fig. 4. The terminal output voltage uab iscontrolled to track the reference uab*. Taking Fig. 4(a) as anexample, when switches S5 and S6 are both turned off, theterminal output voltage uab is equal to ud; when switches S5 andS6 are both turned on, uab is equal to -ud; while only one switchis turned on, uab becomes zero. These three voltage levels areused to synthesize the expected voltage uab*. The emulatorshown in Fig. 4(a) contains only one capacitor and two activeswitches, which can reduce the volume and the controlcomplexity of the system. Therefore, it is adopted to verify theeffectiveness of the proposed control method.

C. Control StrategyThe mathematical model can be established as follows

gg g cdi

L u udt

(11)

cg g recdu

C i idt

(12)

dcdc r ab odiL u u udt

(13)

ds d dcduC d idt

(14)

where irec=dridc, ur =druc and uab = ddud. dr and dd are definedas follows:

1 2

5 61r

d

d d dd d d

(15)

and di (i=1, 2, 3, 4, 5, 6) is the duty ratio of switch Si.The control diagram is depicted in Fig. 5. The rectifier is

used to regulate the input current to achieve high power factoras well as transfer the power to the load. By multiplying idc onboth sides of (13), the following equation can be obtained,

2

2o

dc dcc rec r d dc o dc

Pp

L diu i d u i u i

dt

(16)

where ucirec implies the input power, p~ is the secondarypulsating power and Po is the output power. Ignoring the effectof the LC low pass filter, uc is deemed to be equal to ug.Suppose the input current reference is

* cos( )*rec m gi I t . (17)

By substituting (17) into (16) and using the periodic averagemethod [9], equation (16) turns into be

2

2*dcdc m m odi

L U I Pdt

. (18)

The average value is obtained by using a moving averagefilter (MAF). To regulate the average value of idc, aproportional-integral (PI) controller is employed and *

mI isdesigned as

2* 2 11

1= 2* im dc dc p o

m

kI i i k PU s

(19)

where kp1 and ki1 are the designed controller parameters.The asymmetric H-bridge circuit is controlled to emulate the

behavior of the LC resonator and stabilize the decouplingcapacitor voltage. Based on (10), the reference capacitorvoltage uab* is composed of two parts (u1 and u2 in the controlblock). u1 is obtained by multiplying the DC current (idc) andthe impedance of the LC resonator to achieve power decoupling.And u2 is the product of the virtual resistance Rd* and the DCcurrent (idc) to remain the average decoupling capacitor voltage.The virtual resistance Rd* is designed as

* * 22( )( )i

d d d pk

R u u ks

(20)

where kp2 and ki2 are the corresponding controller parameters,ud* is the average capacitor voltage reference and �ud is achievedby using MAF. Once the control references irec* and uab* areobtained, the duty radios di and dd can be easily calculated.Then, the duty ratio of each switch is designed as

1 2

3 4

5 6

1 0 1 0 0 0 00 0 0 1 0 1 01 0 0 0 1 0 0

r r r

r r r

r r r

r r r

d d d

d d d

d d dd dd d dd d dd dd d dd d dd dd d d

，，，，

，，，，

，，，，

. (21)





It is noted that for the LC emulator, the reference forachieving ripple power decoupling is derived only from idc.And this current sampling circuit can be embedded in thesubmodule of emulating LC resonator.

IV. DISCUSSIONIn this section, comparisons have been carried out among the

proposed control method, the passive dimpling method, andexisting active power decoupling control methods [10-18].

When a real LC resonator is used, the volume is usually largedue to the low resonant frequency. For example, consideringthe parameters Ld=2.5 mH and Cd=1000 μF, the total volume isestimated to be 282.23 cm3. The volume is estimated byadopting the ways in [19] and the capacitors from themanufacturer United Chemi-Con are adopted. However, thetotal volume is only 24.22 cm3 with the proposed method. Onthe other hand, due to the increased semiconductor devices, thereliability of the proposed method is reduced. The failure ratehas been analyzed using the handbook for reliability predictionof electronic equipment MIL-HDBK-217F [20, 21]. The resultsare 0.42 Failures/106 Hours for the passive dimpling methodand 1.01 Failures/106 Hours for the proposed method.

The control methods are generally divided into two kinds,named Kinds A and B, according to whether the controlfacilitates the modularization of the decoupling circuit. In KindA, the ripple power decoupling and the decoupling capacitorvoltage stabilization are both achieved with only controlling thedecoupling circuit (LC emulator in this paper) and onlyknowing the external information of the DC-linkcurrent/voltage. There is no information to be exchangedbetween the decoupling circuit and rectifier/inverter, whichfacilitates the modularization design of the decoupling circuit.The other control methods belong to Kind B. Most of theexiting control methods belong to Kind B, for examples, theripple current compensation control (similar to the principle ofactive power filter) [10], the energy conservation baseddecoupling capacitor voltage tracking control [11], and theautomatic-power-decoupling control [12,13]. In this kind ofcontrol, a central controller is preferred to coordinate theoperations of the decoupling circuit and the rectifier/inverter. Itshould be noted that to reduce component count, there are a lotof switch-multiplexing decoupling circuits [2, 3], in whichthere exist switches playing twofold roles of power decouplingand power conversion. For this kind of decoupling circuit, thedesigned control methods are all belong to Kind B. For thecontrol of Kind A, the decoupling circuit is usually controlledto mimic a physical component, for examples, a capacitor [14,15, 18], an inductor [16, 17, 18] and an LC resonator tuned attwice the grid frequency in this paper. In [14-17], a puredifferential operation is needed and the high-frequency noiseswill be amplified. This issue can be overcome by directlysampling the inductor voltage or capacitor current [18] andadding an inner controller. However, the inductor voltage orcapacitor current is non-smooth which may increase thecomplexity of sampled signal processing. In the proposedmethod, both differential operation and voltage/current sensingnetwork are avoided, and only the inductor current or capacitorvoltage is utilized to emulate the desired dynamics. Therefore,the proposed method can be a good candidate for active power

decoupling control, especially when the modular design of thedecoupling circuit is expected.

V. SIMULATION AND EXPERIMENTAL RESULTSThe proposed control method is verified by the numerical

simulation and the physical test. The numerical simulation wascarried out on the MATLAB/Simulink platform. And thephysical test has been completed on the conducted prototype(as shown in Fig. 6) in the laboratory. The main circuit includesa single-phase current source rectifier, as shown in Fig. 1, andan asymmetric H-bridge circuit, as shown in Fig. 4(a). Theasymmetric H-bridge circuit is in series with the DC-linkinductor. In the experiment, semiconductors used are1MBH60D-100 IGBTs and DSEI60-06A diodes. The controlalgorithm of the converter is realized by a combination ofdigital signal processor (DSP) TMS320F28335 and fieldprogrammable gate array (FPGA) EP2C8T144C8N. Someother specific parameters are listed in table I. And thedecoupling capacitance is determined according to the principleproposed in [22]. The DC inductor current reference (idc*) andthe average capacitor voltage reference (ud*) are set to 6 A and120 V, respectively.

Fig. 7 shows the steady-state waveforms of the DC current idc,the decoupling capacitor voltage ud, the grid voltage ug, and thegrid current ig. Experimental results in Fig. 7(b) match wellwith those in the simulation in Fig. 7(a). The grid current ig issine shaped and in phase with the grid voltage ug. In addition,the load current idc keeps constant at the given reference, whichindicates that an excellent decoupling control is achieved. Forthe capacitor voltage ud, it swings at twice the grid frequency asa result of buffering the ripple power. The measuredefficiencies are 84% and 87% with/without the decouplingcircuit. This issue can be mitigated by using wide-bandgap(WBG) semiconductor devices like the silicon carbide (SiC)and the gallium nitride (GaN).

TABLE IPARAMETERS OF THE EXPERIMENTAL SETUP

Symbol Description Valueug Input grid voltage 110 V(rms)fg Input frequency 50 HzLg Input filter inductance 0.6 mHCg Input filter capacitance 20 μFCs Stored-energy capacitance 100 μFLdc DC inductance 3.6 mHRL Load resistance 6 Ωfs Switching frequency 20 kHz

Fig. 6. Photo of the prototype.





Fig. 7. Steady-state waveforms of grid voltage ug, grid current ig, capacitorvoltage ud and load current idc. (a) Simulation results. (b) Experimental results.

Fig. 8. Dynamic waveforms when changing the resonant frequency. (a)Simulation results. (b) Experimental results.

To further manifest the decoupling effect of the proposedmethod, a test with disabling the proposed control method hasbeen carried out. It is realized by setting the resonant frequencyof the PR controller deviating from 200π rad/s (100Hz) to 100πrad/s (50Hz) on purpose. The dynamic waveforms of thesimulation and experiments are respectively shown in Fig. 8(a)and Fig.8(b). The detuning of the resonator leads to very lowimpedance for the current idc. In this case, the output u1 is nearly

zero and the emulation of LC resonator with 100 Hz resonantfrequency fails. Therefore, the load current idc begins tooscillate and even falls down to zero at the valley. And thedecoupling capacitor voltage is near flat and kept at 120 V dueto that u2 still works. The simulation and experimental resultsmanifest the decoupling effect of the proposed method.

VI. CONCLUSIONThis letter proposes a control strategy to realize power

decoupling in single-phase current source rectifier. Byemploying an electric circuit to obtain the same externalcharacteristics of the passive LC resonator, the output power ofdouble grid frequency is well buffered. From the view ofvolt-second balance, the proposed circuit generates an ACvoltage to compensate the pulsating component and thereforethe ripple voltage of the DC side is eliminated. Theexperimental results verify the effectiveness of emulating LCresonator well. In addition, the proposed idea can be extendedto the single-phase voltage source converter to achieve thesame function.

REFERENCES[1] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey and D. P.

Kothari, “A Review of Single-Phase Improved Power Quality AC-DCConverters,” in IEEE Transactions on Industrial Electronics, vol. 50, no.5, pp. 962-981, Oct. 2003.

[2] H. Hu, S. Harb, N. Kutkut, I. Batarseh, and Z. J. Shen, “A Review ofPower Decoupling Techniques for Microinverters With Three DifferentDecoupling Capacitor Locations in PV Systems,” in IEEE Transactionson Power Electronics, vol. 28, no. 6, pp. 2711-2726, Jun. 2013.

[3] Y. Sun, Y. Liu, M. Su, W. Xiong and J. Yang, “Review of Active PowerDecoupling Topologies in Single-Phase Systems,” in IEEE Transactionson Power Electronics, vol. 31, no. 7, pp. 4778-4794, Jul. 2016.

[4] S. Nonaka and Y. Neba, “Single-Phase PWM Current Source ConverterWith Double-Frequency Parallel Resonance Circuit for DC Smoothing,”in Conf. Rec. IEEE-IAS Annu. Meeting, pp. 1144–1151, 1993.

[5] K. Fukushima, I. Norigoe, M. Shoyama, T. Ninomiya, Y. Harada and K.Tsukakoshi, “Input Current-Ripple Consideration for the Pulse-linkDC-AC Converter for Fuel Cells by Small Series LC Circuit,” in 2009Twenty-Fourth Annual IEEE Applied Power Electronics Conference andExposition, Washington, DC, 2009, pp. 447-451.

[6] K. Hwu, W. Tu and C. Lai, “Light-Emitting Diode Driver WithLow-Frequency Ripple Suppressed and Dimming Efficiency Improved,”in IET Power Electronics, vol. 7, no. 1, pp. 105-113, Jan. 2014.

[7] Yen-Wu Lo and R. J. King, “High Performance Ripple Feedback for theBuck Unity-Power-Factor Rectifier,” in IEEE Transactions on PowerElectronics, vol. 10, no. 2, pp. 158-163, Mar. 1995.

[8] M. Vasiladiotis and A. Rufer, “Dynamic Analysis and State FeedbackVoltage Control of Single-Phase Active Rectifiers With DC-linkResonant Filters,” in IEEE Transactions on Power Electronics, vol. 29,no. 10, pp. 5620-5633, Oct. 2014.

[9] Sanders, J.A., Verhulst, F., Murdock, J., “Averaging Methods inNonlinear Dynamical Systems”, Springer, 1985, 2007, 2nd edn.

[10] R. Wang et al., “A High Power Density Single-Phase PWM RectifierWith Active Ripple Energy Storage,” in IEEE Transactions on PowerElectronics, vol. 26, no. 5, pp. 1430-1443, May 2011.

[11] Y. Ohnuma and J. Itoh, “A Novel Single-Phase Buck PFC AC–DCConverter With Power Decoupling Capability Using an Active Buffer,”in IEEE Transactions on Industry Applications, vol. 50, no. 3, pp.1905-1914, May-June 2014.

[12] Y. Sun, Y. Liu, M. Su, X. Li, and J. Yang, “Active Power DecouplingMethod for Single-Phase Current Source Rectifier With No AdditionalActive Switches,” in IEEE Transactions on Power Electronics, vol. 31,no.8, pp. 5644-5654, Aug. 2016.

[13] S. Li, W. Qi, S.-C. Tan and S. Y. Hui, “EnhancedAutomatic-Power-Decoupling Control Method for Single-PhaseAC-to-DC Converters,” in IEEE Transactions on Power Electronics, vol.33, no. 2, pp. 1816–1828, Feb. 2018.





[14] R. Chen, Y. Liu, F. Z. Peng, “A Solid State Variable Capacitor WithMinimum Capacitor,” in IEEE Transactions on Power Electronics, vol.32, no. 7, pp. 5035-5044, Jul. 2017.

[15] H. Wang and H. Wang, “A Two-Terminal Active Capacitor,” in IEEETransactions on Power Electronics, vol. 32, no. 8, pp. 5893-5896, Aug.2017.

[16] H. Wang and H. Wang, “A Two-Terminal Active Inductor WithMinimum Apparent Power for the Auxiliary Circuit,” in IEEETransactions on Power Electronics, vol. 34, no. 2, pp. 1013-1016, Feb.2019.

[17] N. C. Brooks, S. Qin and R. C. N. Pilawa-Podgurski, “Design of anActive Power Pulsation Buffer Using an Equivalent Series-ResonantImpedance Model,” in 2017 IEEE 18th Workshop on Control andModeling for Power Electronics (COMPEL), Stanford, CA, 2017, pp.1-7.

[18] S. Li, W. Qi, S.-C. Tan, S. Y. Hui and C. K. Tse, “A General Approach toProgrammable and Reconfigurable Emulation of Power Impedances,” inIEEE Transactions on Power Electronics, vol. 33, no. 1, pp. 259–271, Jan.2018.

[19] D. Zhao, W. Liu, K. Shen, G. Zhao and X. Wang, “Multi-ObjectiveOptimal Design of Passive Power Filter for Aircraft Starter/GeneratorSystem Application,” in The Journal of Engineering, vol. 2018, no. 13, pp.636-641, 2018.

[20] Department of Defense, Washington, D.C. Military Handbook ReliabilityPrediction of Electronic Equipment, MIL-HDBK-217F, Dec. 2, 1991,Notice 2, Feb. 28, 1995.

[21] J. L. Soon, D. D. C. Lu, J. C. Peng and W. Xiao, “ReconfigurableNon-isolated DC-DC Converter With Fault-Tolerant Capability,” inIEEE Transactions on Power Electronics, early access, 2020.

[22] H. Han, Y. Liu, Y. Sun, M. Su and W. Xiong, “Single-Phase CurrentSource Converter With Power Decoupling Capability Using aSeries-Connected Active Buffer,” in IET Power Electronics, vol. 8, no. 5,pp. 700-707, May 2015.


activepowerdecouplingcontrolfor single ...pe.csu.edu.cn/lunwen/122-active power decoupling control...

Documents