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Improved Analysis, Design and Control for
Interleaved Dual-Phase ZVS GaN-Based Totem-Pole
PFC Rectifier with Coupled Inductor
Qingyun Huang, Qingxuan ma, Ruiyng Yu,
Tianxiang Chen, Alex Q. Huang
Department of Electrical and Computer Engineering
University of Texas at Austin
Austin, USA
Zhuoran Liu
University of Chinese Academy of Sciences,
Beijing, China
Abstract—This paper proposes the improved analysis,
design and control for the interleaved dual-phase ZVS
GaN-based totem-pole PFC rectifier with coupled indu-
ctor. Traditionally, the analysis and control of the coupled-
inductor-based dual-phase totem-pole PFC are not only
complicated, but also significantly different from those of
the non-coupled-inductor-based dual-phase totem-pole
PFC. In this paper, a Δ-type circuit model for the coupled
inductor is proposed to be utilized. Based on the Δ-type
coupled inductor model, the coupled-inductor-based PFC
can be simplified as a non-coupled-inductor-based PFC
with an auxiliary inductor between the two phases. Thus,
this paper proposes to simplify all the analysis, design and
control of the coupled-inductor-based dual-phase totem-
pole PFC to those of the non-coupled-inductor-based dual-
phase totem-pole PFC with an auxiliary inductor. Based
on this novel concept, the simplified analysis, the closed-
form analytical model and the full-range ZVS control
strategy are proposed and discussed. Finally, the proposed
concepts are verified by the experimental results.
Keywords—Dual-phase interleaving; GaN Totem-pole PFC;
coupled inductor; modeling; analysis and control, ZVS; auxiliary
inductor.
I. INTRODUCTION
The electricity consumed by the datacenters and the telecommunication equipment is dramatically growing recently [1], [2]. It is predicted that by 2020, roughly 10% of the total electricity will be required for the datacenters and the telecom-munication equipment [1], [2]. Therefore, the high-efficiency and high-density switching-mode AC/DC power supplies for the datacenters and telecommunication equipment are drawing more and more attention [1], [2].
The commercial AC/DC power supplies for the datacenters and telecommunication equipment contain two conversion stages: the AC/DC power factor corrector (PFC); and the isolated DC/DC converters. The isolated DC/DC converters mostly use the LLC resonant converters due to the high
efficiency [1]. For the PFC, there are several high-performance topologies: the Boost PFC; the semi-bridgeless PFC; and the totem-pole bridgeless PFC [1]-[3].
Compared with the Boost PFC and the semi-bridgeless PFC, the totem-pole bridgeless PFC has lower conduction loss [1]-[3], [8], [9]. However, the totem-pole bridgeless PFC cannot use 650V super-junction (SJ) Si MOSFETs due to the reverse recovery issue [4]. With the emerging 650V GaN FETs, the reverse recovery issue is eliminated [1], [2], [4]-[10]. In addition, the 650V GaN FETs significantly reduce the switching loss and the driving loss, compared with the SJ Si MOSFETs [1], [2], [4]-[10]. Thus, the GaN-based totem-pole bridgeless PFC for the datacenters and telecommunication equipment is drawing more and more interests.
(a)
(b)
Fig. 1. The GaN-based dual-phase totem-pole PFC with coupled inductors:
(a) negative coupling; (b) positive coupling
978-1-5386-1180-7/18/$31.00 ©2018 IEEE 2077
−
−
−
(a) (b)
Fig. 2. Equivalent circuit models of coupled inductors: (a) Y-type model for
negative coupling; (b)Y-type model for positive coupling;
−
−
−
−
(a) (b)
Fig. 3. Equivalent circuit models of coupled inductors: (a) -type model for
negative coupling; (b) -type model for positive coupling.
The triangular current mode (TCM) zero-voltage switching (ZVS) operation can eliminate the switching turn on loss of the totem-pole PFC, while it introduces high current ripple [8]-[11]. Dual phase interleaving technique can significantly reduce the current ripple, while one more magnetic component is added [8], [11]. Therefore, the dual-phase interleaved ZVS totem-pole GaN PFC with coupled inductor [12], [13], as shown in Fig. 1, becomes an interesting solution for magnetic size reduction.
However, based on the traditional circuit models of the coupled inductor, the analysis and control of the coupled-inductor-based PFC are not only complicated, but also signify-cantly different from those of the non-coupled-inductor-based PFC [13]-[17].
Among the various circuit models for the coupled inductor, the Y-type-model is the most popular and the simplest one due to the elimination of the transformer [13]-[17]. The Y-type circuit models are shown in Fig. 2 (a), (b). The coupling coefficient is defined as
(1)
where is the mutual inductance, and is the self-inductance.
In the equivalent circuits of the Y-type model as shown in Fig. 2, there are three inductors. From C to the middle point O, the inductor is - for the negative coupling, and for the
positive coupling. From the middle point O to A or B, the inductor is for the negative coupling, and for
the positive coupling. In the equivalent circuit model of the Y-type model, is the current flowing from the middle point O
to A, and is the current flowing from the middle point O to
B. By observing the current waveforms of and as shown
in Fig. 5, there are three equivalent inductances during one
switching period. The three equivalent inductances are discussed in [13], [14], [17]. And two of them are dependent on the duty-cycles [13], [14], [17]. Thus, the analysis and control for the coupled-inductor-based PFC is quite compli-cated, especially for the AC/DC application whose duty-cycles are continuously varying.
In this paper, the -type circuit model for the coupled
inductor is proposed to be utilized. As shown in Fig. 3 (a), (b), there are three inductors in the circuit: two Boost inductors and one auxiliary inductor between two switching nodes. For the two Boost inductors, one is between C and A, and another
one is between C and B. The auxiliary inductor is
between A and B. Based on the -type circuit model for the
coupled inductor, the coupled-inductor-based PFC can be simplified as a non-coupled-inductor-based PFC with an auxiliary inductor between the two phases. Since all the voltage over the three inductors are always known, there is not any duty-cycle-dependent inductance in the analysis. Thus, all the analysis, design and control of the coupled-inductor-based PFC can be simplified as those of the non-coupled-inductor-based PFC with an auxiliary inductor. Based on this novel concept, the detailed analysis, the closed-form analytical model and the full-range ZVS control strategy are proposed.
This paper is organized as follows. In Section II, the improved modeling and the operation analysis of the coupled inductor based on the -type model are discussed. In Section
III, the closed-form analytical model and full-range ZVS control are proposed. In Section IV, the experimental verification is included. Section V concludes this paper.
II. IMPROED MODELING AND OPERATION ANALYSIS OF
COUPLED INDUCTOR
By the equivalent circuit transformation of Y-type-model, the -type equivalent circuit models are derived as shown in
Fig. 3 (a), (b). Based on this model, the coupled-inductor-based dual-phase PFC can be simplified as a non-coupled-inductor-based dual-phase PFC with an auxiliary inductor ( ) between
the two switching nodes. The two Boost inductors ( and
) and the auxiliary inductor ( ) are shown in Fig. 3 (a),
(b). To simplify the analysis, only positive half line cycle is considered. The equivalent circuit of the PFC in positive half-line cycle is shown in Fig. 4.
Fig. 4. The equivalent circuit of the coupled-inductor-based totem-pole PFC
in positive half line cycle.
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A. Inductances and Voltages
For the negative coupling, the two Boost inductors are expressed as
. (2)
The auxiliary inductor is expressed as
. (3)
is a negative inductor for the negative coupled inductor.
For the positive coupling, the two Boost inductors are expressed as
. (4)
The auxiliary inductor is expressed as
. (5)
is a positive inductor for the negative coupled inductor.
The voltage of from C to A is calculated as:
(6)
The voltage of from C to B is calculated as:
(7)
The voltage of from A to B is calculated as:
(8)
Thus, based on the -type model for the coupled inductor, all
the voltages over the inductors are known as (6)-(8). And the voltages are independent on the inductances.
B. Inductor Currents for ZVS
Based on the -type model for the coupled inductor and
the voltages over the inductors, all the inductor currents can be derived as shown in Fig. 5.
The auxiliary inductor of the negative coupled inductor
is a negative inductor. To achieve TCM ZVS for and , the
currents should fulfill the following requirements:
(9)
(a) (b)
(a) (b)
Fig. 5. Operation waveforms in the positive half line cycle: (a) D>0.5,
negative coupled inductor; (b) D<0.5, negative coupled inductor; (c) D>0.5,
positive coupled inductor; (d) D<0.5, positive coupled inductor.
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-´
-´
-´
-´
t, )
t)
(a)
-´
-´
-´
-´
t, )
t, )
t, )
t )
t )
t )
(b)
Fig. 6. The therritical current ripples under the conditions: ,
, and total power . (a) peak currents of Boost inductors
and auxiliary inductor; (b) comparison of current ripples for the input AC current .
where is the valley current of and , and is the
peak current of . This requirement means that more negative
currents are required for and of the negative coupled
inductor, compared with those of the non-coupled inductor.
On the contrary, the auxiliary inductor of the positive
coupled inductor is a positive inductor. To achieve TCM ZVS for and , the currents should fulfill the following
requirements:
(10)
This requirement means that less negative currents are required for and of the positive coupled inductor, compared with
those of the non-coupled inductor.
Based on the -type model, it is easy to analyze the ZVS
operation and conditions for the coupled inductor converter. For the negative coupled inductor, more negative currents are needed for the Boost inductors, since the auxiliary inductor is negative. For the positive coupled inductor, less negative currents are needed for the Boost inductors, since the auxiliary inductor is positive. In summary, under the same average
current conditions, to achieve ZVS, less current ripples of
and are required for positive coupled inductor compared
with those of the negative coupled inductor.
C. Input Current Ripples
Under the same ZVS conditions and the same average current conditions, the current ripples of and for positive
coupled inductors are less than those for the non-coupled inductors and the negative coupled inductors. Thus, the total input current ripples of the positive coupled inductors are much less than those of the non-coupled inductors and negative coupled inductors.
Fig. 6 shows an example of the total input current ripples for the positive coupled inductors, the negative coupled induc-tors, and the non-coupled inductors under ZVS conditions. In Fig. 6, , , and the total power
. As shown in Fig. 6, the total current ripples of
the positive coupled inductors are much less than those of the other two cases.
III. CLOSED-FORM ANALYTICAL MODEL ADN FULL-RANGE
ZVS CONTROL
To explore the full range ZVS for the coupled-inductor-based totem-pole PFC, the state plane trajectory of the inductor current and the drain to source voltage is depicted in
Fig. 7. In Fig. 7, the center of the circle is expressed as:
negative coupling (11)
positive coupling (12)
The characteristic impedance is derived as:
. (13)
Using the -type model of the coupled inductor, this paper
proposes to calculate all the currents based on the non-coupled-
Fig. 7. State plane trajectory for and
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TABLE I. THREE-STEP CALCULATIONS AND EQUATIONS FOR FULL-RANGE ZVS
Step 1: calculations of at the down side resonant
period
Step 4: calculations of with coupling
Negative coupling Positive coupling
Valley current of , Peak current of ,
Active switch on current of I1,
Valley current of L11,
Step 2: calculations of i11 under non coupling conditions ( )
Active switch on current of L11,
Peak current of L11 without coupling,
SR off current of ,
Valley current of L11 without coupling,
Active switch on time,
Step 3: calculations of the auxiliary inductor current SR switch on time,
Peak current of L12,
D>0.5 D<0.5 D>0.5 D<0.5
inductor-based dual-phase totem-pole PFC first, and then insert the currents of the auxiliary inductor into the previous
calculations. All the currents and timing information can be derived by three steps based on the following parameters: the input voltage , the output voltage , the average grid
current, , the self-inductance , the coupling coefficient ,
the drain to source capacitance of the GaN device , and the
required synchronous rectifier (SR) turn off current for
ZVS. The calculation methodology and equations are listed in Table I.
The system control strategy for full-range ZVS is shown in Fig. 8. The open loop interleaving method with turn-on instant synchronization [18] is adopted here. The SR turn on time
and the active switch turn on time can be calculated based
on Table I. The zero-crossing-detection (ZCD) signal obtained by sensing the inductor current is the synchronization signal
for the timer of the master phase. As shown in Fig. 8, the turn on instant of the master phase is the synchronization signal for the timer of the slave phase. With a half switching-period delay, the active switch of the slave phase is turned on.
IV. EXPERIMENTAL RESULTS
The prototype of the dual-phase GaN-based totem-pole PFC is shown in Fig. 9. This prototype utilizes the Navitas 650V driver-integrated GaN devices. Then, one coupled induc-tor replaces the two individual inductors. The preliminary experimental results for the negative and positive coupled inductors under DC/DC conditions are shown in Fig. 10, where
, , , . These results have
verified the proposed modeling, analysis, design, and control. ZVS can be achieved for both two phases under different conditions. The ferrite core is ELP32 with the material ML91S from Hitachi.
Fig. 8. Control strategy and modulation
Fig. 9. Prototype of the dual-phase GaN-based totem-pole PFC with coupled inductor
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(a)
(b)
(c)
(d)
Fig. 10. Test waveforms where for and , and 2A/div for
and : (a) negative coupling, ; (b) negative coupling, ; (c)
positive coupling ; (d) positive coupling .
V. CONCLUSIONS
Based on the -type coupled inductor model, this paper
proposes to simplify all the analysis, design and control of the coupled-inductor-based PFC to those of the non-coupled-inductor-based PFC with an auxiliary inductor. For the nega-
tive coupled inductor, the auxiliary inductor is a negative inductor, while for the positive coupled inductor, the auxiliary inductor is a positive inductor. All the voltages over the inductors in the -type model are always known and inde-
pendent on the inductances. To achieve ZVS, less negative currents are needed for the Boost inductors of the positive coupled inductor, compared with those of the negative coupled inductors. Thus, under the same average current conditions, to achieve ZVS, the positive-coupled-inductor-based PFC has much less grid input current ripple than the negative-coupled-inductor-based PFC. In addition, the closed-form analytical model based on the three-step-calculations is proposed in this paper. Moreover, the ZVS control strategy is also discussed in this paper. The proposed concepts are verified by the experim-ental results based on a prototype of the GaN-based dual-phase interleaved totem-pole PFC with coupled inductor.
ACKNOWLEDGMENT
This work was conducted with the use of GaN device samples donated by Navitas.
REFERENCES
[1] F. C. Lee, Q. Li, Z. Liu, Y. Yang, C. Fei and M. Mu, "Application of GaN devices for 1 kW server power supply with integrated magnetics," in CPSS Transactions on Power Electronics and Applications, vol. 1, no. 1, pp. 3-12, Dec. 2016.
[2] Q. Huang and A. Q. Huang, "Review of GaN totem-pole bridgeless PFC," in CPSS Transactions on Power Electronics and Applications, vol. 2, no. 3, pp. 187-196, Sept. 2017.
[3] L. Huber, Y. Jang and M. M. Jovanovic, "Performance Evaluation of Bridgeless PFC Boost Rectifiers," in IEEE Transactions on Power Electronics, vol. 23, no. 3, pp. 1381-1390, May 2008.
[4] A. Q. Huang, "Wide bandgap (WBG) power devices and their impacts on power delivery systems," 2016 IEEE International Electron Devices Meeting (IEDM), San Francisco, CA, 2016, pp. 20.1.1-20.1.4.
[5] E. A. Jones, F. F. Wang and D. Costinett, "Review of Commercial GaN Power Devices and GaN Converter Design Challenges," in IEEE
Journal of Emerging and Selected Topics in Power Electronics, vol. 4,
no. 3, pp. 707-719, Sept. 2016. [6] E. Persson, “How 600 V GaN transistors improve power supply
efficiency and density,” Power Electron. Eur., no. 2, pp. 21–24, Mar.
2015. [7] E. Persson, “Practical application of 600 V GaN HEMTs in power
electronics,” in Proc. IEEE Appl. Power Electron. Conf. Expo. (APEC),
Mar. 2015. [8] Z. Liu, F. C. Lee, Q. Li and Y. Yang, "Design of GaN-Based MHz
Totem-Pole PFC Rectifier," in IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 4, no. 3, pp. 799-807, Sept. 2016.
[9] Z. Liu, Z. Huang, F. C. Lee and Q. Li, "Digital-Based Interleaving Control for GaN-Based MHz CRM Totem-Pole PFC," in IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 4, no. 3, pp. 808-814, Sept. 2016.
[10] Q. Huang, R. Yu, A. Q. Huang and W. Yu, "Adaptive zero-voltage-switching control and hybrid current control for high efficiency GaN-based MHz Totem-pole PFC rectifier," 2017 IEEE Applied Power Electronics Conference and Exposition (APEC), Tampa, FL, 2017, pp. 1763-1770.
[11] C. Marxgut, F. Krismer, D. Bortis and J. W. Kolar, "Ultraflat Interleaved Triangular Current Mode (TCM) Single-Phase PFC Rectifier," in IEEE Transactions on Power Electronics, vol. 29, no. 2, pp. 873-882, Feb. 2014.
[12] Z. Liu; B. Li; F. Lee; Q. Li, "High-Efficiency High-Density Critical Mode Rectifier/Inverter for WBG Device Based On Board Charger," in IEEE Transactions on Industrial Electronics , vol.PP, no.99, pp.1-1
2082
[13] Y. Yang, Z. Liu, F. C. Lee and Q. Li, "Multi-phase coupled and integrated inductors for critical conduction mode totem-pole PFC converter," 2017 IEEE Applied Power Electronics Conference and Exposition (APEC), Tampa, FL, 2017, pp. 1804-1809.
[14] F. Yang, X. Ruan, Y. Yang and Z. Ye, "Interleaved Critical Current Mode Boost PFC Converter With Coupled Inductor," in IEEE Transactions on Power Electronics, vol. 26, no. 9, pp. 2404-2413, Sept. 2011.
[15] D. O. Boillat and J. W. Kolar, "Modeling and experimental analysis of a Coupling Inductor employed in a high performance AC power source," 2012 International Conference on Renewable Energy Research and Applications (ICRERA), Nagasaki, 2012, pp. 1-18.
[16] G. Zhu, B. A. McDonald and K. Wang, "Modeling and Analysis of Coupled Inductors in Power Converters," in IEEE Transactions on Power Electronics, vol. 26, no. 5, pp. 1355-1363, May 2011.
[17] Pit-Leong Wong, Peng Xu, P. Yang and F. C. Lee, "Performance improvements of interleaving VRMs with coupling inductors," in IEEE Transactions on Power Electronics, vol. 16, no. 4, pp. 499-507, Jul 2001.
[18] L. Huber, B. T. Irving and M. M. Jovanovic, "Open-Loop Control Methods for Interleaved DCM/CCM Boundary Boost PFC Converters," in IEEE Transactions on Power Electronics, vol. 23, no. 4, pp. 1649-1657, July 2008.
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