デルタシグマ変調を用いた...高虹, 美和俊介, 小堀康功, 邢林 小林春夫,...
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◎ 高 虹, 美和俊介, 小堀康功, 邢 林
小林春夫, 高井伸和, 新津葵一 (群馬大学)
大森武志, 小田口貴宏, 中西功, 根本謙治
(AKMテクノロジー株式会社)
松田順一(旭化成パワーデバイス株式会社)
デルタシグマ変調を用いたDC-DC変換器制御の検討
1
電気学会電子回路研究会(岡山県立大)
2011年7月1日
2Contents
● Research Background and Objective
● PWM and ΔΣ Controllers in DC-DC Converter
● Feedforward-type ΔΣ Controller in DC-DC Converter
● ΔΣ Controller for Single-Inductor Dual-Output DC-DC Converter
● Conclusion
3Contents
● Research Background and Objective
● PWM and ΔΣ Controllers in DC-DC Converter
● Feedforward-type ΔΣ Controller in DC-DC Converter
● ΔΣ Controller for Single-Inductor Dual-Output DC-DC Converter
● Conclusion
4Research Background
● Rapid advances of Power DevicesFast switching speed
Application of ΔΣ modulator to DC-DC converter controller becomes feasible.
● Expected advantages- Fast transient response- High efficiency at low load- Spread spectrum of switching noise
5Research Objective
● To show advantages of feed-forward-type ΔΣ controllerover feedback-type in DC-DC converter.
Feedback-type ΔΣ controller one clock signal delay
Feed-forward type no signal delay- small ripple- fast response
● To investigate applicability of ΔΣ controllerin single-inductor dual-output DC-DC converter.
6Contents
● Research Background and Objective
● PWM and ΔΣ Controllers in DC-DC Converter
● Feedforward-type ΔΣ Controller in DC-DC Converter
● ΔΣ Controller for Single-Inductor Dual-Output DC-DC Converter
● Conclusion
7Trade-off of Fast Response and Efficiency
High Switching Frequency
Faster Transient Response Inductor charged and dischargedat high speed
High Efficiency
Reduction of Switch Operation
Low Switching Frequency
Lower Switching Loss
8Problems of PWM Controller
Switching frequency determined by sawtooth wave
Difficult to meet simultaneously both of ・ Fast Transient Response・ High Efficiency
Switching Period
Output of Error Amp
PWM Output
time
time
DC-DC converter with PWM controller
9ΔΣ Modulator Controller
Low input Sparse Pulse Stream(at steady state) (Low switching frequency)
High input Dense Pulse Stream(at transient state) (High switching frequency)
High efficiency:
Fast transient Response:
ΔΣM Controller+
-
Error Amp
Vref
input
Low
highDC/DC Converter Output
⇒
⇒
ΔΣ modulator output
Can meet both
time
10Contents
● Research Background and Objective
● PWM and ΔΣ Controllers in DC-DC Converter
● Feedforward-type ΔΣ Controller in DC-DC Converter
● ΔΣ Controller for Single-Inductor Dual-Output DC-DC Converter
● Conclusion
11Feedback-type ΔΣ Modulator
Signal Transfer Function Noise Transfer Function
One-clock delay Differentiation=Noise Shaping
12Feedback-type ΔΣ Modulator and Operation
Sampling Frequency∝
Number of Pulses
Ph1 Ph1Ph2 Ph2clocking
Vref -Vref
しきい値
サンプリング周期
Vref
-Vref入力信号
出力信号
積分器出力
0Output Signal
Input Signal
Threshold Voltage
Sampling period
Output of Integrator
Error
Amp
output Switch
on/off
control
131st-order Feedforward ΔΣ Modulator
ぉΣ Low Pass Filter ADCΣ
DAC
+
―
+A(in) Vout
No Delay Differentiation=Noise Shaping
ぉΣ H(z) Σ
+
―
+
E(z)
X(z)Y(z)
STF = 1 NTF=
1st -order FF ΔΣ
142nd-order Feedforward-type ΔΣ Modulator
2nd-order FF ΔΣSTF = 1 NTF=
No Delay 2nd-order Differentiation
15ΔΣ Modulator as DC-DC Converter Controller
Vref+
-Controller
RoutCoutR1
R2
● Feedback ΔΣ modulatorOne-clock signal delay (disadvantage)
● Feedforward ΔΣ modulatorNo signal delay (advantage)
phase & gain margin improvementsmall ripplefast transient response
Vout
LVin
We expect
16Simulation Condition
Vin: 3VL: 4.7uHCout: 47uFRout: 50ΩVref: 600mVFs: 400kHz (PWM)Fs:800kHz(ΔΣ)
Vref+
-Controller
RoutCoutR1
R2
① PWM controller② 1st-order feedback ΔΣ modulator③ 1st-order feedforward ΔΣ modulator④ 2nd-order feedfoward ΔΣ modulator
VoutL
Vin
Boost DC-DC Converter
17Output Ripple Voltage (Simulation Results)
time/mSecs 5uSecs/div
4.605 4.61 4.615 4.62 4.625 4.63
VO
UT
/ V
5.0326
5.0328
5.033
5.0332
5.0334
5.0336
5.0338
5.034
5.0342
5.0344
time/mSecs 5uSecs/div
4.605 4.61 4.615 4.62 4.625 4.63
VO
UT
/ V
4.9906
4.9908
4.991
4.9912
4.9914
4.9916
4.9918
4.992
4.9922
4.9924
time/mSecs 50uSecs/div
4.65 4.7 4.75 4.8 4.85 4.9 4.95 5
VO
UT
/ V
5.0866
5.0868
5.087
5.0872
5.0874
5.0876
5.0878
5.088
5.0882
5.0884
PWM Controller
1st-order Feedback ΔΣ modulator
1st-order Feedforward ΔΣ modulator
2nd-order Feedforward ΔΣ modulator
0.1mV
1.1mV
0.23mV
0.6mV
time/mSecs 20uSecs/div
4.62 4.64 4.66 4.68 4.7 4.72 4.74 4.76 4.78 4.8
VO
UT
/ V
5.004
5.0042
5.0044
5.0046
5.0048
5.005
5.0052
5.0054
5.0056
5.0058
18Transient Response Simulation
Vref
+
-Controller
Cout
50Ω
At 8ms Zout: 10Ω 5ΩAt 10.5ms Zout: 5Ω 10Ω
Zout
19Transient Response Simulation
time/mSecs 500uSecs/div
7 7.5 8 8.5 9 9.5
VO
UT
/ V
4.4
4.6
4.8
5
5.2
5.4
time/mSecs 200uSecs/div
9.8 10 10.2 10.4 10.6 10.8 11 11.2 11.4 11.6 11.8
VO
UT
/ V
4.7
4.9
5.1
5.3
5.5
Zout: 10Ω 5Ω
(Iout: 0.5A 1A)
Zout: 5Ω 10Ω
(Iout : 1A 0.5A)
time/mSecs 2mSecs/div
6 8 10 12 14
IPR
OB
E1 /
A
0.5
0.6
0.7
0.8
0.9
1
PWM
1st- order Feedback ΔΣ modulator
1st-order Feedforward ΔΣ modulator
2nd- order Feedforward ΔΣ modulator
Output Current IoutAt 8ms
At 10.5ms
20Simulation Results Summary
ModulatorState
PWM 1st-order Feedback ΔΣ
1st -order Feedforward ΔΣ
2nd-order Feedforward ΔΣ
Steady State
Ripple 0.1mV 1.1mV 0.6mV 0.23mV
TransientState(fall)
Ripple 0.18V 0.15V 0.083V 0.074V
Time 0.68ms 0.55ms 0.28ms 0.28ms
PWM controller case: steady state ripple smallestbut transient response slowest
2nd-order feedforward ΔΣ modulator is the best among 3 ΔΣ modulators.This is due to
- No signal delay- Noise is 2nd-order shaped - High-frequency noise is reduced by LC circuit
①
①
②
① ①
④ ③
②④ ③
③④
21Contents
● Research Background and Objective
● PWM and ΔΣ Controllers in DC-DC Converter
● Feedforward-type ΔΣ Controller in DC-DC Converter
● ΔΣ Controller for Single-Inductor Dual-Output DC-DC Converter
● Conclusion
22Background of Single-Inductor Dual-Output DC-DC Converter
Conventional Dual-output Converter Signal-Inductor Dual-Output Converter
DC/DC Vout1
Vout2
Vin
DC/DC
DC/DC
Vout1
Vout2
Vin
Inductor L×2Bulky, expensive
Inductor L×1Small, cheap
23Background of Single-Inductor Dual-Output DC-DC Converter
Conventional Dual-output Converter Signal-Inductor Dual-Output Converter
DC/DC Vout1
Vout2
Vin
DC/DC
DC/DC
Vout1
Vout2
Vin
Inductor L×2Bulky, expensive
Inductor L×1Small, cheap
Hot Research Topic
24Operation Principle of SIDO
t
I L
Inductor Current
Vout1 Vout2
Dual-boost converter
Vin
Vout1
Vout2
L
S1
S3
S2
Dual outputs by time-division usage of inductor
25Simulation Condition
S2
Vin
Vref1
Vout1
+
-ΔΣ変調
ドライバ
Vout2
Vref2+
-ΔΣ変調
L
S1
S3
S1,S2,S3へ
Rout1Cout1
Rout2Cout2 R3
R4
R2
R1
Driver
PWM vs. ΔΣ
PWM vs. ΔΣ
Vin: 3VL: 1uHCout1,2: 200uFRout1,2: 200ΩR1,3: 9KΩR2,4: 1KΩVref1: 500mVVref2: 700mVFs:1MHz(PWM)Fs: 5MHz(ΔΣ)
26Simulation Results with PWM Controller
S2
Vin
Vref1
Vout1
+
-ΔΣ変調
ドライバ
Vout2
Vref2+
-ΔΣ変調
L
S1
S3
S1,S2,S3へ
Rout1Cout1
Rout2Cout2 R3
R4
R2
R1
Driver
PWM
PWM
0.32V
0.47V
Vout1 (Vref1=7.0V)
Vout2 (Vref2=5.0V)
27
0.035V
0.018V
S2
Vin
Vref1
Vout1
+
-ΔΣ変調
ドライバ
Vout2
Vref2+
-ΔΣ変調
L
S1
S3
S1,S2,S3へ
Rout1Cout1
Rout2Cout2 R3
R4
R2
R1
Driver
ΔΣ
ΔΣ
Vout1 (Vref1=7.0V)
Vout2 (Vref2=5.0V)
Simulation Results with Feedforward ΔΣ Controller
Smaller ripple voltage
28SIDO & ΔΣ Modulator
● We here showed
ΔΣ modulator is applicable to SIDO converter
● Zout1 changes Vout1, Vout2 change
ΔΣ modulator high switching freq. operation
Vout1, Vout2 recover soon
(fast response and good cross-regulation)
29Contents
● Research Background and Objective
● PWM and ΔΣ Controllers in DC-DC Converter
● Feedforward-type ΔΣ Controller in DC-DC Converter
● ΔΣ Controller for Single-Inductor Dual-Output DC-DC Converter
● Conclusion
30Conclusion
・ As the DC-DC Converter Controller
ΔΣ Modulator excels PWMMerit: Fast transient response
FeedForward ΔΣ Modulator excels Feedback-typeSecond-Order Modulator excels First-Order
Merits : Small output voltage ripple Fast transient response
・ ΔΣ Modulator applicable to SIDO DC-DC Converter
31Future Work
● Efficiency evaluation of DC-DC converter
with ΔΣ modulator
● Application of ΔΣ modulator to
current-mode control
● Application of ΔΣ modulator to
AC-DC converter
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