3kW_Four-Level_Flying_Capacitor_Totem-Pole_Bridgeless_PFC_Rectifier_with_200V_GaN_Devices

Prévia do material em texto

3kW Four-Level Flying Capacitor Totem-Pole 
Bridgeless PFC Rectifier with 200V GaN Devices 
 
Qingyun Huang 
Semiconductor Power 
Electronics Center 
The University of Texas 
at Austin 
Austin, Texas, USA 
qyhuang@utexas.edu 
Qingxuan Ma 
Semiconductor Power 
Electronics Center 
The University of Texas 
at Austin 
Austin, Texas, USA 
qxma@utexas.edu 
Pengkun Liu 
Semiconductor Power 
Electronics Center 
The University of Texas 
at Austin 
Austin, Texas, USA 
pkliu@utexas.edu 
Alex Q. Huang 
Semiconductor Power 
Electronics Center 
The University of Texas 
at Austin 
Austin, Texas, USA 
aqhuang@utexas.edu 
Michael de Rooij 
Efficient Power 
Conversion 
El Segundo, California, 
USA 
michael.derooij@epc-
co.com 
 
Abstract—This paper introduces a flying capacitor multilevel 
(FCML) totem-pole bridgeless power-factor-correction (PFC) 
rectifier for the high-efficiency and high-density switching power 
supplies of data centers. A 3kW four-level FCML totem-pole PFC 
with 200V GaN devices is discussed and designed in this paper. 
Compared with the conventional two-level GaN totem-pole PFC, 
this four-level FCML GaN totem-pole PFC utilizes the low voltage 
GaN devices, reduces the switching voltage, reduces the voltage 
stress on the inductor and increases the equivalent ripple 
frequency of the inductor. Since the reduced switching voltage also 
reduces the dv/dt, the EMI noises are also reduced. Based on the 
commercial cubic composite inductors, a modular compact and 
low-profile inductor design method is introduced for this four-
level totem-pole PFC. A high density 3kW four-level-FCML GaN 
totem-pole PFC prototype is developed and tested. The working 
principles, control strategy and performance of this PFC rectifier 
are verified by the experimental results. The estimated peak 
efficiency of the prototype is 99%, and the power density is about 
125W/in3. 
Keywords—totem-pole PFC, flying capacitor multilevel 
converter, GaN, high efficiency, high density, modular inductor 
I. INTRODUCTION 
Due to the increased usage and size of the data centers, the 
data centers have extremely high demand for energy consum-
ption. The efficiency, the power density and the cost of the 
AC/DC switching power supplies for data centers are much 
more important [1]. The typical two stage power supply 
solution is widely used for the 48V mother boards: a power-
factor-correction (PFC) rectifier to build the 400V DC link, and 
an isolated DC/DC stage to convert the 400V DC link to 48V. 
The bulky DC link capacitors provide the energy decoupling 
and hold-up time. 
To improve the system efficiencies of the power supplies, 
the high-efficiency PFC rectifiers are drawing a lot of interest. 
Due to the high conduction loss of the conventional Boost PFC, 
various bridgeless PFC topologies are discussed [2]. The dual-
Boost bridgeless PFC removes two line-frequency diodes, but 
its conduction loss is still high, since there are still two low 
frequency diodes in the circuit. Besides, since the two Boost 
converters work alternatively, the utilizations of the inductors 
and the devices in the dual-Boost PFC are low [2]-[3]. The 
totem-pole bridgeless PFC is considered as a major solution 
recently, since the 650V GaN FETs have addressed the concern 
of the severe reverse recovery issue [4]-[6]. The GaN totem-
pole PFC has two high frequency 650V GaN FETs, two line-
frequency 650V Si MOSFETs and one inductor, as shown in 
Fig. 1. This topology minimizes the conduction loss, and highly 
utilizes the devices and the inductor. 
The conventional GaN totem-pole PFC is a two-level PFC 
rectifier. It has been proven with 99% efficiency for kW level 
application. Both the switching voltage of the devices and the 
voltage swing of the inductor are 400V. 650V Enhancement-
Mode GaN devices are still expensive. For hard-switching 
continuous conduction mode (CCM) operations, the switching 
frequency is normally under 100kHz to minimize the switching 
loss. The size of the main inductor is not reduced compared 
with the traditional hard-switching Boost rectifier. The soft-
switching two-level GaN totem-pole PFC reduces the inductor 
 
Fig. 1. Traditional two-level GaN totem-pole PFC 
 
Fig. 2. Four-Level FCML Si totem-pole PFC 
978-1-7281-0395-2/19/$31.00 ©2019 IEEE 81
Authorized licensed use limited to: UDESC - Universidade do Estado de Santa Catarina. Downloaded on September 21,2022 at 19:46:12 UTC from IEEE Xplore. Restrictions apply. 
size. However, the complexity of the sensing and control 
system is much more complicated compared with the hard-
switching CCM one. 
The Flying capacitor multilevel (FCML) converters are 
traditionally used for medium voltage power electronics [7]-[9]. 
Recently, they have also been demonstrated to achieve high 
efficiency and high density for low voltage grid connected 
applications [10]. A 1.5kW bridgeless seven-level FCML Boost 
PFC is reported in [13]. With twelve 100V GaN devices which 
work at 150kHz, the peak efficiency is 99.07%. However, in 
this topology, there are 4 line-frequency Si MOSFETs while 
totem-pole PFC has only two of them. Besides, the loss is not 
evenly distributed between the high side devices and low side 
devices, since the Boost PFC is not a symmetrical topology. 
The FCML totem-pole bridgeless PFC topology combines 
the FCML Boost converter and the totem-pole PFC, as shown 
in Fig. 2. It addresses the issues of the FCML Boost bridgeless 
PFC. And it can achieve high efficiency, high power-density 
and low cost. A 200W four-level FCML totem-pole PFC 
rectifier with 200V Si MOSFETs is reported in [14]. The 
topology is shown in Fig. 2. However, due to the high switching 
loss and reverse recovery losses of 200V Si MOESFETs, the 
efficiency is only around 98% at 150kHz switching frequency. 
A 3kW three-level FCML totem-pole PFC with 150V Si 
MOSFETs in series is implemented with 99% efficiency in [15], 
since the performance of 150V Si MOSFETs is significantly 
improved compared with 200V Si MOSFETs. The topology is 
shown in Fig. 3. However, due to the low switching frequency 
70kHz and three level operation, the main inductor size is still 
large, and not improved a lot compared with two-level GaN 
totem-pole PFC. 
Based on the previous work on the FCML totem-pole PFC, 
a four-level FCML GaN totem-pole PFC rectifier with 200V 
Enhancement-Mode GaN devices are designed, analyzed and 
implemented in this paper. The topology is shown in Fig. 4. 
Compared with the conventional two-level totem-pole PFC, 
this FCML totem-pole PFC has the following benefits: the 
utilization of low voltage devices, the reduced switching 
voltage, the reduced voltage swing on the inductor, and the 
increased equivalent ripple frequency of the inductor. 
Compared with the Si-based FCML totem-pole PFC, this four-
level GaN PFC achieves both high density and high efficiency. 
A modular low-profile inductor design method is introduced for 
this PFC. Besides, the system control strategy for this PFC is 
discussed. A 3kW prototype with EPC 2047 are developed and 
tested. The operations, control and performance are verified by 
the experimental results. 
II. GENERALIZED TOPOLOGY OF FCML TOTEM-POLE PFC 
The generalized topology of the FCML totem-pole PFC is 
shown in Fig. 5. In the line frequency leg, and are still the 
Si 650V super-junction MOSFETs which have low on-
resistance and low cost. The high frequency leg consists a 
FCML Boost. In this FCML leg, to are on the high side, 
and to are on the low side. There are flying 
capacitors. This FCML leg has levels. And the voltage on 
the flying capacitor is (e.g., , , …, 
). 
 (1) 
The phase-shift pulse-width-modulation (PSPWM) can be 
used for this FCML leg, since PSPWM has the natural voltage-
balance capability for FCML converters [11]-[12]. With PS-
PWM, to use the phase shifted gating signals, and 
to use the complementarygating signals of to 
respectively. The duty-cycle of the high-side switches is . The 
duty cycle is expressed as follows. 
 (2) 
 
Fig. 3. Three-Level FCML Si totem-pole PFC with devices in series 
 
Fig. 4. Four-Level FCML GaN totem-pole PFC 
 
Fig. 5. Generalized topology of FCML totem-pole PFC 
82
Authorized licensed use limited to: UDESC - Universidade do Estado de Santa Catarina. Downloaded on September 21,2022 at 19:46:12 UTC from IEEE Xplore. Restrictions apply. 
In this FCML totem-pole PFC, the voltage stresses on the 
high frequency devices ~ are . In the high 
frequency leg, this FCML totem-pole PFC can utilize low 
voltage Si MOSFETs which have much better reverse recovery 
performance than Si MOSFETs. In addition, the cost of 
the low voltage Si MOSFETs is much less than the GaN 
FETs. Low voltage GaN FETs can be utilized to further 
improve the efficiency. Moreover, the voltage swing on the 
inductor is also significantly reduced. The effective inductor 
current ripple frequency is , if the switching frequency of 
each high frequency device is . Therefore, both the inductance 
and the size of the inductor are reduced, compared with the two-
level totem-pole PFC. 
III. DESIGN AND ANALYSIS OF FOUR-LEVEL FCML GAN 
TOTEM-POLE PFC 
As shown in Fig. 4, four-level FCML totem-pole PFC has 
low voltage high frequency devices in the high frequency leg. 
The voltage stress on each GaN device is . 
 (3) 
The voltage stress on is , and the voltage stress on 
is 2 . 
, (4) 
Since the DC link voltage is 400V, the voltage stress of the high 
frequency devices is 133V. 200V devices are suitable in this 
topology. 
A. Selection of Low Voltage Devices 
Due to the multilevel operation, the low voltage switching 
devices can be used in this PFC application. For four-level 
operation, 200V device is enough. With 150V devices, five-
level operations are required. If 100V devices are used, seven-
level operations are more suitable. In Table I, the state-of-art 
200V Si device, 150V Si device and 100V device and 200V E-
Mode GaN device are compared in detail. To make the 
comparison fair, the total for conducting the same current 
with each type of device is between to . 
There are three normalized figure of merits (FOMs) listed in 
Table I. The device performance is better with smaller FOMs. 
FOM1( ) is the key factor describing the driving 
speed. The driving speed is faster if FOM1 is smaller. For Si 
devices, the driving speed is improved a lot with the lower 
voltage devices. From 200V Si device to 150 Si device, FOM1 
is improved with 2.6 times. However, with 200V E-Mode GaN 
device EPC2047, FOM1 is improved with 6.7 times compared 
with 200V Si device, and 1.9 times even compared with 100V 
Si device. The cause is that the input capacitance of GaN device 
is much smaller than Si devices. 
FOM2( ) explains the performance of the switching 
loss for both hard-switching and soft-switching. The switching 
loss is lower with smaller FOM2. For Si devices, the lower the 
voltage stress, and the lower the FOM2. However, considering 
the different testing voltage conditions for different devices, the 
improvement is not too much with lower voltage devices. 
However, 200V GaN device has much lower FOM2 than 200V 
Si device. It has similar FOM2 even compared with 100V Si 
device if considering the different testing voltage. 
FOM3( ) describes the performance of the reverse 
recovery loss. The reverse recovery loss is less if FOM3 is 
smaller. For Si devices, FOM3 of 150V Si device is reduced by 
85% compared with FOM3 of 200V Si device. The reverse 
recovery loss is significantly reduced by using 150V Si devices. 
However, E-Mode GaN device has zero reverse recovery loss. 
GaN FET is ideal for synchronous rectification. 
In summary, 200V E-Mode GaN FET has much lower 
switching loss, reverse recovery loss and driving loss, compared 
with 200V Si devices. 100V Si devices are improved a lot 
compared with 200V Si devices. However, if 100V Si devices 
are used for FCML totem-pole PFC, seven level operation is 
required. The system control complexity and reliability suffer a 
lot. However, with 200V E-Mode GaN devices, only four level 
operation is required, and the switching loss is even a little bit 
lower, and the reverse recovery loss is zero. And its driving loss 
is also much lower. Therefore, four-level GaN totem-pole PFC 
is an optimized solution based on the semiconductor com-
parison. 
B. Voltage-Seconds on Inductor 
Since the equivalent ripple frequency is three times of the 
switching frequency in four-level FCML totem-pole PFC, this 
multilevel operation significantly reduces the filter capacitors if 
the current ripple is the same. 
TABLE I. COMPARISON OF LOW VOLTAGE DEVICES 
83
Authorized licensed use limited to: UDESC - Universidade do Estado de Santa Catarina. Downloaded on September 21,2022 at 19:46:12 UTC from IEEE Xplore. Restrictions apply. 
For the main inductor, the impact of the multilevel operation 
can be explained by the calculation of the voltage-second on the 
inductor. According to the Faraday's Law, the voltage-second 
can be expressed as follows. 
, (5) 
where is the voltage-second, is the inductance, is the 
current ripple, N is the turns number, is the maximum flux 
density variation, is the effective cross-section area of the 
core. Based on (5), if the voltage-second is lower, the 
inductance can be lower with the same current ripple. And the 
turns number or the effective area can be smaller. Therefore, 
with lower voltage-second, the inductance is lower, and the size 
of the inductor is also smaller. 
Fig. 6 shows that the voltage-second of the inductor in this 
four-level totem-pole PFC is significantly reduced compared 
with that in the two-level totem-pole PFC. For the calculation of 
Fig. 6, DC link voltage is 400V, AC voltage is 240VAC, and the 
switching frequency is 100kHz. For two-level PFC, the 
switching voltage is 400V and the frequency is 100kHz. For 
four-level PFC, the switching voltage is 133.4V, the switching 
frequency for each device is 100kHz, and there are 3 devices 
switching with interleaving. Assuming the switching speed of 
650V GaN device for two-level PFC and the 200V GaN device 
for four-level PFC is similar, the total switching loss should be 
similar. With the similar switching loss, 72 reduction of the 
averaged voltage-second over a line cycle on the inductor is 
achieved in this four-level totem-pole PFC, compared with that 
of two-level totem-pole PFC. Even though 72% reduction of the 
voltage-second doesn’t mean 72% reduction of the inductor size, 
the inductance and the inductor size will still be significantly 
reduced compared with the two-level totem-pole PFC. 
IV. INDUCTOR DESIGN BASED ON MODULAR HIGH-DENSITY 
AND LOW-PROFILE INDUCTOR 
The switching frequency of the two-level GaN totem-pole 
CCM PFC is about or lower than 100kHz, to achieve high 
efficiency. Since the DC current value is high in CCM PFC, the 
DC flux is high. High saturation flux magnetic material is 
usually preferred in this application. Some toroid powder cores 
based on some high saturation flux magnetic materials, such as 
Kool Mu, High Flux, etc., are used a lot in CCM PFC application 
operating at around 100kHz switching frequency. However, 
with these powder cores, the inductance could be significantly 
reduced at high DC current. For example, if the inductance at 
zero current is the original inductance, the inductance might be 
around 30% of the original inductance at designed maximum 
current. That means, if the required inductance at maximum 
current for a 3kW 100kHz two-level totem-pole PFC is , 
the original inductance at zero current should be around . 
The large inductance and the large inductor size could still be 
the limitations for two-level totem-pole PFC. 
As discussedin the previous section, the inductance for the 
four-level PFC is much lower compared with two-level totem-
pole PFC. In this paper, the switching frequency is 100kHz, the 
current ripple frequency is 300kHz, and the required inductance 
is around . In the four-level GaN totem-pole PFC, the 
high saturation flux is still required for the inductor. The toroid 
powder cores for two-level totem-pole PFC are not suitable for 
the four-level totem-pole PFC. First, these toroid powder cores 
achieve high efficiency usually at around 100kHz switching 
frequency or even lower. However, for this four-level PFC, the 
current ripple frequency is 300kHz if the switching frequency is 
100kHz. Thus, these toroid powder cores are not efficient for 
this frequency range. In addition, the toroid cores are not suitable 
for high density design, since the toroid cores are not low-
profile, and usually occupy a lot of converter space. 
The ferrite cores can be much more efficient for several 
hundred kHz. And there are a lot of low-profile planner ferrite 
cores with different sizes. However, due to their much lower 
saturation flux, the ferrite cores need much more turns number 
 
Fig. 6. Reduction of voltage-second on the inductor 
§
§
§
x10-5
t(s)
t(s)
 
Fig. 7. Picture of Vishay IHLP-5050FD-01 series inductor [16] 
 
Fig. 8. inductor made by four in series 
 
Fig. 9. A generalized modular inductor design concept 
84
Authorized licensed use limited to: UDESC - Universidade do Estado de Santa Catarina. Downloaded on September 21,2022 at 19:46:12 UTC from IEEE Xplore. Restrictions apply. 
or cross-section area. The inductor size and the winding loss 
could be large. 
For the low voltage high current DC/DC applications, such 
as notebook, desktop, servers and POL converters, there are a 
lot of commercial composite inductors. These composite indu-
ctors are usually made by some powdered iron cores. The 
powdered irons integrate the distributed airgaps with the iron. 
Therefore, the powdered iron has much higher saturation flux 
compared with ferrite. And the powdered iron cores have very 
stable inductance at high DC current. Even approaching the 
saturation current, the inductance reduction is very soft. In these 
composite inductors, the powdered iron cores are pressed around 
the inductor coils. The inductor coils are welded to the lead 
frame [17]. These composite inductors have high DC saturation 
current, stable inductance, and soft saturation characteristic. 
They are very compact and low profile. Due to the powdered 
iron material which have low core loss for high frequency 
operation, these inductors are very efficient for the switching 
frequencies from several hundred kHz to MHz. Since the 
powdered iron is low-cost, these composite inductors are low-
cost. 
Fig. 7 shows an example of Vishay IHLP commercial 
inductors IHLP-5050FC-01 series. In this series, the inductance 
can be chosen from (120A) to (15.5A). The size is 
12.9x13.2x6.4mm3. For a inductor, the saturation current 
is 35A, and the DC resistance is . This inductor is high-
density, efficient and low-cost. However, the inductance is still 
too low for the four-level totem-pole PFC. Since these comer-
cial composite inductors are very cubic, compact and low-
profile, this paper proposes to use the commercial inductors as 
modular inductor building blocks to build bigger cubic and low-
profile inductors. To get higher inductance, the multiple indu-
ctors are in series. In this paper, a (35A) inductor is built 
by four (35A) in series. As shown in Fig. 8, by proper 
arrangement, this 13.2uH (35A) inductor is very cubic and low-
profile, and the size is 25.8x26.4x6.4mm3. A more generalized 
modular inductor design based on the commercial composite 
inductors is shown in Fig. 9. With the modular cubic and low-
profile inductors, the bigger cubic and low-profile inductors can 
be developed. These modular inductors can be connected in 
series or parallel. Series connection provides higher inductance, 
and parallel connection provides higher current capability. The 
modular inductors can be put on both sides of the PCB to further 
utilize the system space. 
V. CONTROL STRATEGY AND SIMULATION RESULTS 
The control strategy of this four-level totem-pole PFC is 
shown in Fig. 10. This control strategy is based on the dual-loop 
control including the outer DC voltage loop and the inner AC 
current loop. Fig. 11 shows the basic operation principles and 
signal waveforms, including the duty-cycle and the gating 
signals. 
The duty-cycle is for the high side devices. The duty-cycle 
 has a step change during the AC zero crossing as shown in Fig. 
10. This step change is a challenge for the dynamic response of 
AC current control loop. To solve this issue, a feedforward 
signal is added to the output of the AC current controller. The 
calculation of is expressed as follows. 
 (4) 
Since the feedforward signal is the big signal of the duty-
cycle, the step change of the duty-cycle is generated by this 
feedforward signal. The feedforward signal also compensates 
the variation of the input and output voltages. Therefore, the 
output of the AC current controller can be a smaller number 
around zero, and it doesn’t include the step change signal. With 
this feedforward signal, the dynamic response of the AC current 
control loop is improved. 
 
Fig. 11. Operation waveforms and principles 
 
Fig. 10. Control strategy 
+
_
+
_ + +
85
Authorized licensed use limited to: UDESC - Universidade do Estado de Santa Catarina. Downloaded on September 21,2022 at 19:46:12 UTC from IEEE Xplore. Restrictions apply. 
The PWM signals are generated by the duty-cycle and 
PSPWM. The voltage balancing is naturally achieved by 
PSPWM. The gating signals for line frequency switches and 
 are determined by the AC voltage polarity detection. 
The simulation results are shown in Fig. 12. The conditions 
for simulations are as follows: , , 
, . Fig. 12 shows the well-controlled AC 
current, the multilevel waveforms and the balanced flying 
capacitor voltages. This topology and control are verified by the 
simulation results. 
VI. HARDWARE DESIGN AND EXPERIMENTAL RESULTS 
In this paper, a 3kW four-level FCML GaN totem-pole PFC 
is developed and tested. Fig. 13 shows the photos of the 
prototype. Fig. 13 (a) shows the photo of the four-level FCML 
GaN totem-pole PFC card. 200V GaN devices (EPC2047) are 
utilized for the high frequency leg. In the low frequency leg, the 
Si devices IPT60R028G7XTMA1 are used. The size of the PFC 
card is 3.07x1.65x0.43in3. The power density of this power stage 
card is 1380W/in3. This GaN PFC card is a power stage module. 
This GaN PFC card includes the switching devices, the drivers, 
the driver power supplies, and inductor current sensor. This GaN 
card can be used as a PFC module in the PFC system. It is very 
compact and low profile. The driver power supply solution uses 
the cascaded bootstrap method [18]. This solution provides 
multiple driver power supplies without any transformers. And 
this solution is compact and low-cost. 
The whole PFC system, including the GaN PFC card, the 
controller card, the DC bulky capacitors, EMI filter, relay, etc., 
is shown in Fig. 13(b). The size of this whole PFC prototype is 
4.76x2.87x1.77in3, and the density is 125W/in3. Fig. 14 shows 
the experimental waveforms under the following conditions: 
, , . Fig. 14 shows the well-
controlled inductor current and the multilevel waveforms. 
VII. CONCLUSIONS 
This paper discusses the FCML totem-pole bridgeless PFC 
rectifier. A 3kW four-level FCML GaN totem-pole PFC with 
200V GaN devices is analyzed, designed and implemented in 
this paper. Compared with the conventional two-level GaN 
totem-pole PFC, this four-level FCML GaN totem-pole PFC has 
the following benefits: utilization of the low voltage GaN 
devices, reduced switching voltage, reduced voltage stress onFig. 12. Simulation results 
 
(a) Four-level FCML GaN totem-pole PFC card 
 
(a) Four-level FCML GaN totem-pole PFC system 
Fig. 13. Hardware of 3kW Four-level FCML GaN totem-pole PFC 
 
Fig. 14. Experimental waveforms 
86
Authorized licensed use limited to: UDESC - Universidade do Estado de Santa Catarina. Downloaded on September 21,2022 at 19:46:12 UTC from IEEE Xplore. Restrictions apply. 
the inductor and increased equivalent ripple frequency of the 
inductor. The detailed comparison is shown in Table II. The 
reduced switching voltage reduces the CM noises. Assuming the 
two-level PFC and the four-PFC has the same switching 
frequency, such as 100kHz, the total switching loss should be 
similar. However, due to the achieved 72 reduction of the 
averaged voltage-second over a line cycle on the inductor, the 
inductance and the inductor size will be significantly reduced 
compared with the two-level totem-pole PFC. Therefore, the 
modular inductor design based on the commercial composite 
inductors is introduced in this paper. The commercial composite 
inductors with powdered ferrite iron cores are low-profile and 
compact. They have high DC saturation currents and low core 
loss for several hundred kHz to MHz operations. Using these 
cubic composite inductors as the inductor building blocks to 
build the larger cubic inductors with series or parallel connec-
tions. This method makes the inductor design more convenient, 
standard and low-cost. This paper also introduces the control 
strategy for the four-level totem-pole PFC. A 3kW four-level-
FCML GaN totem-pole PFC prototype is developed and tested. 
This prototype achieves a power density of 125W/in3. The four-
level-FCML totem-pole GaN PFC power stage card has a power 
density of 1380W/in3. The estimated peak efficiency is 99%. 
ACKNOWLEDGMENT 
The authors would like to thank EPC for GaN device sample 
and financial support of this work. 
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] 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. 
[3] Y. Jang and M. M. Jovanovic, "A Bridgeless PFC Boost Rectifier With 
Optimized Magnetic Utilization," in IEEE Transactions on Power 
Electronics, vol. 24, no. 1, pp. 85-93, Jan. 2009. 
[4] 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. 
[5] L. Zhou, Y. Wu, J. Honea and Z. Wang, "High-efficiency True Bridgeless 
Totem Pole PFC based on GaN HEMT: Design Challenges and Cost-
effective Solution," Proceedings of PCIM Europe 2015; International 
Exhibition and Conference for Power Electronics, Intelligent Motion, 
Renewable Energy and Energy Management, Nuremberg, Germany, 
2015, pp. 1-8. 
[6] 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. 
[7] J. Rodriguez, Jih-Sheng Lai and Fang Zheng Peng, "Multilevel inverters: 
a survey of topologies, controls, and applications," in IEEE Transactions 
on Industrial Electronics, vol. 49, no. 4, pp. 724-738, Aug. 2002. 
[8] H. Abu-Rub, J. Holtz, J. Rodriguez and G. Baoming, "Medium-Voltage 
Multilevel Converters—State of the Art, Challenges, and Requirements 
in Industrial Applications," in IEEE Transactions on Industrial 
Electronics, vol. 57, no. 8, pp. 2581-2596, Aug. 2010. 
[9] S. S. Fazel, S. Bernet, D. Krug and K. Jalili, "Design and Comparison of 
4-kV Neutral-Point-Clamped, Flying-Capacitor, and Series-Connected 
H-Bridge Multilevel Converters," in IEEE Transactions on Industry 
Applications, vol. 43, no. 4, pp. 1032-1040, July-aug. 2007. 
[10] Y. Lei et al., "A 2-kW Single-Phase Seven-Level Flying Capacitor 
Multilevel Inverter With an Active Energy Buffer," in IEEE Transactions 
on Power Electronics, vol. 32, no. 11, pp. 8570-8581, Nov. 2017. 
[11] B. P. McGrath and D. G. Holmes, "Natural Capacitor Voltage Balancing 
for a Flying Capacitor Converter Induction Motor Drive," in IEEE 
Transactions on Power Electronics, vol. 24, no. 6, pp. 1554-1561, June 
2009. 
[12] B. P. McGrath and D. G. Holmes, "Analytical Determination of the 
Capacitor Voltage Balancing Dynamics for Three-Phase Flying Capacitor 
Converters," in IEEE Transactions on Industry Applications, vol. 45, no. 
4, pp. 1425-1433, July-aug. 2009. 
[13] S. Qin, Y. Lei, Z. Ye, D. Chou and R. C. N. Pilawa-Podgurski, "A High 
Power Density Power Factor Correction Front End Based on Seven-Level 
Flying Capacitor Multilevel Converter," in IEEE Journal of Emerging and 
Selected Topics in Power Electronics. 
[14] T. T. Vu and G. Young, "Implementation of multi-level bridgeless PFC 
rectifiers for mid-power single phase applications," 2016 IEEE Applied 
Power Electronics Conference and Exposition (APEC), Long Beach, CA, 
2016, pp. 1835-1841. 
[15] T. T. Vu and E. Mickus, "99% Efficiency 3-Level Bridgeless Totem-pole 
PFC Implementation with Low-voltage Silicon at Low Cost," 2019 IEEE 
Applied Power Electronics Conference and Exposition (APEC), 
Anaheim, CA, USA, 2019, pp. 2077-2083. 
[16] Vishay. (2019). IHLP -5050FD-01 datasheet. [Online]. Available: 
https://www.vishay.com/docs/34123/ihlp-5050fd-01.pdf 
[17] Vishay. (2019). INDUCTORS 101 Instructional Guide. [Online]. 
Available: http://www.vishay.com/docs/49782/49782.pdf 
TABLE II. COMPARISON OF TWO-LEVEL GAN TOTEM-POLE PFC AND FOUR-LEVEL FCML GAN TOTEM-POLE PFC 
 Two Level GaN totem-pole PFC Four Level FCML GaN totem-pole PFC 
High Frequency Switches 2(650V GaN) 6(200V GaN) 
Drivers 2 6 
Auxiliary power supplies for 
drivers 
1+1 bootstrap power supply 1 + 5 cascaded bootstrap power supplies 
Inductor ripple frequency at 
100kHz switching frequency 
100kHz 300kHz 
Inductor core design at 100kHz 
switching frequency 
Toroid powder cores (Kool Mu, MPP, High Flux...) 
Modular cubic inductor design based on commercial 
composite cubic inductors (powdered iron cores) 
Inductance at 100kHz switching 
frequency 
165µH (about 50µH at maximum current) 13.2µH 
Switching voltage 400V 133.3V 
 
87
Authorized licensed use limited to: UDESC - Universidade do Estado de Santa Catarina. Downloaded on September 21,2022 at 19:46:12 UTC from IEEE Xplore. Restrictions apply. 
[18] Z. Ye, Y. Lei, Z. Liao and R. C. N. Pilawa-Podgurski, "Investigation of 
capacitor voltage balancing in practical implementations of flying 
capacitor multilevel converters," 2017 IEEE 18th Workshop on Control 
and Modeling for Power Electronics (COMPEL), Stanford, CA, 2017, pp. 
1-7. 
88
Authorized licensed use limited to: UDESC - Universidade do Estado de Santa Catarina. Downloaded on September 21,2022 at 19:46:12 UTC from IEEE Xplore. Restrictions apply. 
 
 
 
 HistoryItem_V1
 TrimAndShift
 
 Range: all pages
 Trim: none
 Shift: move up by 12.60 points
 Normalise (advanced option): 'original'
 
 
 32
 
 D:20170126085122
 792.0000
 US Letter
 Blank
 612.0000
 
 Tall
 1
 0
 No
 675
 322
 Fixed
 Up
 12.6000
 0.0000
 
 
 Both
 AllDoc
 
 PDDoc
 
 None
 0.0000
 Top
 
 
 QITE_QuiteImposingPlus2
 Quite Imposing Plus 2.9
 Quite Imposing Plus 2
 1
 
 
 8
 7
 8
 
 1
 
 
 HistoryItem_V1
 TrimAndShift
 
 Range: From page 1 to page 1
 Trim: none
 Shift: move up by 5.40 pointsNormalise (advanced option): 'original'
 
 
 32
 1
 0
 No
 675
 322
 Fixed
 Up
 5.4000
 0.0000
 
 
 Both
 1
 SubDoc
 1
 
 
 PDDoc
 
 None
 0.0000
 Top
 
 
 QITE_QuiteImposingPlus2
 Quite Imposing Plus 2.9
 Quite Imposing Plus 2
 1
 
 
 8
 0
 1
 
 1
 
 HistoryList_V1
 qi2base