A Study on EMI Noise Reduction
in Boost-Type PFC Circuit
Noriyuki Oiwa, Shotaro Sakurai, Nobukazu Tsukiji,
Yasunori Kobori, Haruo Kobayashi
Division of Electronics and Informatics
Gunma University
IPS03 Analog and Power
April 28, 2018 (Wed)
Gunma Univ. Kobayashi Lab
Outline
• Background and Purpose
• Conventional PFC Power Supply
• Proposed PFC Power Supply
-Using frequency modulation
• Diode recovery current reduction
• Conclusion
2/31
Outline
• Background and Purpose
• Conventional PFC Power Supply
• Proposed PFC Power Supply
-Using frequency modulation
• Diode recovery current reduction
• Conclusion
3/31
What is Power Supply Circuit ?
• Commercial power supply circuits
➞ Convert AC into DC voltages
4
AC-DC
Output Voltage
(ex. DC 300V)Input Voltage
(50/60Hz 100V)
DC-DC
Power Supply
4/31
Research Purpose
AC-DC converter improvement
● EMI noise reduction in PFC circuit
➞Using noise spectrum spread
with frequency modulation
● Efficiency improvement in high speed operation
➞ Diode recovery current reduction
with SiC SBD
PFC: Power Factor Correction
SBD: Schottky Barrier Diode5/31
EMI Noise
● EMI noise generation by current flow
● Large scale analog filter for EMI noise removal
EMI: Electro-Magnetic Interference
Radiation noise
Conduction noise
6/31
Am
plit
ud
e
Frequency Frequency
Am
plit
ud
e
Noise Spectrum Spread
• Reducing peaks of higher harmonics
of clock frequency
➝ Spreading noise energy
by frequency modulation
Without spreading With spreading 7/31
Problem (High Speed Clock)
Clock frequency increase
Fast response, Small L, C
Large noise, energy loss
Low clock freq.
High clock freq.
8/31
[t]
[t]
Vo
lta
ge[v
]V
olt
age
[v]
Outline
• Background and Purpose
• Conventional PFC Power Supply
• Proposed PFC Power Supply
-Using frequency modulation
• Diode recovery current reduction
• Conclusion
9/31
L
C
C
Role of PFC Circuit
PFC shapes input current waveform
Without PFC With PFC
10/31
PFC Operation
PFC Circuit
Input current, input voltage: same waveforms
➞ Harmonics reduction
➞ Loss reduction
PFC=Effective power
Apparent 𝑝𝑜𝑤𝑒𝑟=
ሶV ሶIdt
തVതI
PFC: Power Factor Correction
Apparent 𝑝𝑜𝑤𝑒𝑟
Active 𝑝𝑜𝑤𝑒𝑟 eactive 𝑝𝑜𝑤𝑒𝑟
Active 𝑝𝑜𝑤𝑒𝑟 (↑) eactive 𝑝𝑜𝑤𝑒𝑟(↓)
Apparent 𝑝𝑜𝑤𝑒𝑟(=)11/31
Conventional PFC Circuit
EMIFilter
FixedFrequency
IntegrationCircuit
Error Amp1
Comp1Error Amp2
Gatedriver
C
L
Boost Converter
PFC
12/31
Outline
• Background and Purpose
• Conventional PFC Power Supply
• Proposed PFC Power Supply
- Using frequency modulation
• Diode recovery current reduction
Conclusion
13/31
EMIFilter
FMClock
Error Amp1
Error Amp2
Comp1
Gatedriver
IntegrationCircuit
C
L
Proposed PFC Circuit
14/31
Frequency Modulation
• Frequency modulation fluctuates
clock freq. linearly by time
➞ Clock noise spectrum is spread
[V]
[V]
[t]
[t]
VCO: Voltage Controlled Oscillator
VCO
Triangle wave
Modulation clock
15/31
PFC Circuit for Simulation
16/31
EMIFilter
Integration Circuit
Clock Signal(100kHz)
AC 100V
50Hz
330μF
2.2mH
=400V
Gatedriver
Error Amp2
Comp1Gatedriver
PWM
ClockSignal
Integration Circuit
Simulation Results of Conventional PFC
Measuring point of
Fourier transform 17/31
PWM spectrum
Frequency/kHertz 100kHertz/div
0 100 200 300 400 500
Spectr
um
(PW
M0)
/ V
1m
10m
100m
1
10
Am
plit
ude[
V]
Frequency[kHz]
9.5V
100kHz point
3.1V
1.0V
(∆f=±10kHz)
(∆f=±1kHz)
9.7dB lower than
using fixed freq.
Simulation Results of Proposed PFC
18/31
PWM spectrum
Am
plitu
de[V
]
Frequency[kHz]
Frequency/kHertz 100kHertz/div
0 100 200 300 400 500
Spectr
um
(PW
M0)
/ V
1m
10m
100m
1
10
Frequency/kHertz 100kHertz/div
0 100 200 300 400 500
Spectr
um
(PW
M0)
/ V
1m
10m
100m
1
10
Simulation Results of Proposed PFC
100kHz point
3.1V
1.0V
(∆f=±10kHz)
(∆f=±1kHz)
19.6dB lower than
using fixed freq.
9.7dB lower than
using fixed freq.
19/31
PWM spectrum
Am
plitu
de[V
]
Frequency[kHz]
Frequency/kHertz 100kHertz/div
0 100 200 300 400 500
Spectr
um
(PW
M0)
/ V
1m
10m
100m
1
10
Frequency/kHertz 100kHertz/div
0 100 200 300 400 500
Spectr
um
(PW
M0)
/ V
1m
10m
100m
1
10
Output Voltage Ripple
• Clock frequency changes
→ Output voltage ripple
does not change much.
200kHz ±1.0kHz100kHz ±1.0kHz
time/mSecs 5mSecs/div
500 505 510 515 520 525 530 535 540
Vo /
V
397
398
399
400
401
402
403
Volt
age[V
]
Time[ms] time/mSecs 5mSecs/div
500 505 510 515 520 525 530 535 540
Vo /
V397
398
399
400
401
402
403
Volt
age[V
]
Time[ms]
20/31
Outline
• Background and Purpose
• Conventional PFC Power Supply
• Proposed PFC Power Supply
-Using frequency modulation
• Diode recovery current reduction
• Conclusion
21/31
Diode Recovery Current
• Generated at turn off moment
➞ Loss enlarged by clock frequency increase
ON OFFOFF
0
(t)
(t)-
P
P
N
N
Hole
Electron
+
+
-
Forward voltage
Reverse Voltage
22/31
Recovery Current Reduction Approach
• Schottky Barrier Diode(SBD) usage
Breakdown voltage: Si (200V) < SiC (600V)
SiC usage
23/31
Metal
Electron transfer
Semiconductor
Potential[V]
Electron transfer
Metal Semiconductor
Potential[V]
SiC Features
Comparison of SiC with Si
● Pro - High breakdown voltage
- High speed operation
● Con - High cost
Cost of SiC as a part is high.
But a whole system using SiC may become lower.
24/31
Recovery Current Generation Location
EMIFilter
Gatedriver
ClockSignal
Error Amp1
Error Amp2
Comp1
25/31
SBD Simulation Circuit
• Only diode simulation
• Observing a change in voltage, current and
power at the same measurement point
・PN(20ETS12)
・SiC-SBD(SCS206AJHR)
10Ω
DC 20V
SW 500kHz
Measurement point
26/31
Simulation Results
PN
SiC-SBD
27/31
Vd2 /
V-10
-6
-2
Id2 /
A
-40
-10
20
Time/uSecs 200nSecs/div
3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4Pow
er(
D6)
/ W
-300
0
300
Vd1 /
V
-10
-6
-2
Id1 /
A
-40
-10
20
Time/uSecs 200nSecs/div
3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4Pow
er(
D2)
/ W
-300
0
300
Time[μs]
Time[μs]
106W
-40A
-16A
280W
Vd2 /
V-10
-6
-2
Id2 /
A
-40
-10
20
Time/uSecs 200nSecs/div
3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4Pow
er(
D6)
/ W
-300
0
300
Vd1 /
V
-10
-6
-2
Id1 /
A
-40
-10
20
Time/uSecs 200nSecs/div
3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4Pow
er(
D2)
/ W
-300
0
300
Time[μs]
Time[μs]
106W
-40A
-16A
280W
Recovery Current Comparison
PN
SiC-SBD
Recovery current
reduction by 24A
28/31
Vd2 /
V
-10
-6
-2Id
2 /
A
-40
-10
20
Time/uSecs 200nSecs/div
3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4Pow
er(
D6)
/ W
-300
0
300
Vd1 /
V
-10
-6
-2
Id1 /
A
-40
-10
20
Time/uSecs 200nSecs/div
3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4Pow
er(
D2)
/ W
-300
0
300
Time[μs]
Time[μs]
106W
-40A
-16A
280W
Switching Loss Comparison
PN
SiC-SBD
Switching loss
reduction by 37.9 %
29/31
Outline
• Background and Purpose
• Conventional PFC Power Supply
• Proposed PFC Power Supply
-Using frequency modulation
• Diode recovery current reduction
• Conclusion
30/31
Conclusion
Proposal for PFC power supply in high speed
● PFC with frequency modulation
Fixed frequency ➞ Frequency modulation
EMI noise reduction
● Diode recovery current reduction
SiC-SBD employment
Comparison with switching loss
of PN diodes and SiC-SBD
Efficiency improvement 31/31
32/31
質問事項
・リカバリー電流の過渡応答時間は?
→ 次の機会までに調べます。
→Simplisシミュレーション結果
・SiC使用 : 0.2 [ps] ・Si使用 : 1.3 [ps]
33/31