环路补偿

45 0 -45 -90 -135 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
11
共轭复极点 Click to edit Master title style
20 MAGNITUDE (dB) 0 -20 -40 -60
10 100 1,000 10,000 100,000 1,000,000 Q=2 Q=1 Q=0.5 Q=0.25
10
右半平面零点 Click to edit Master title style
60 MAGNITUDE (dB) 40 20 0 -20 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
s 1− ωZ H( s) = 1
PHASE (°)
8
单个零点 Click to edit Master title style
60 MAGNITUDE (dB) 40 20 0 -20 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
s 1+ ωZ H( s) = 1
PHASE (°)
135 90 45 0 -45 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
1+
s ωZ
⎞ ⎟ ⎟ ⎠
19
电流模式升压功率级 Click to edit Master title style
VI N
L
VO U T
CI N RS +
Logic
40
CO U T RO U T RE S R
20
A VC
ωP 2⋅π
0 GAIN (dB)
ωL 2⋅π
ωR 2⋅ π ωZ 2⋅ π
Σ
VOUT = VIN ⋅
D NS ⋅ 1− D NP
降压 -升压 / 反激式
Flyback Converter
6
极点/零点回顾 Click to edit Master title style
单个极点 单个零点 反相零点 (Inverted Zero) 右半平面零点 共轭复极点
7
单个极点 Click to edit Master title style
1 ⋅ C OUT
Km ≈
ωZ =
R ESR
ωL =
ˆ OUT v ≈ A VC ˆC v
⎛ s ⎞ ⎛ s ⎞ ⎜ ⎜1 − ω ⎟ ⎟⋅⎜ ⎜1 + ω ⎟ ⎟ R ⎠ ⎝ Z ⎠ ⎝ ⋅ ⎛ s ⎞ ⎛ s ⎞ ⎜ ⎜1 + ω ⎟ ⎟⋅⎜ ⎜1 + ω ⎟ ⎟ ⎝ P ⎠ ⎝ L ⎠
20
电流模式降压 -升压功率级 Click to edit Master title style
180 135 PHASE (°) 90 45 0
-45
1,000,000
FREQUENCY (Hz)
15
实用的反馈理论 Click to edit Master title style
交越频率
•
相位裕量
• • • •
控制环路的带宽决定了环路对于某种 瞬态状况的响应速度 通常都会优先选择较高的交越频率， 但存在着实际的限制。经验法则是将 其设定为开关频率的 1/5 至 1/10 0°（增益裕量） 时的衰减以及开关频率 下的衰减也是很重要的
9
反相零点 Click to edit Master title style
60 MAGNITUDE (dB) 40 20 0 -20 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
ωZ 1+ s H( s) = 1
PHASE (°)
45 0 -45 -90 -135 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
Click to edit Master title style
环路补偿很容易
1
课程的目的 Click to edit Master title style
� � � � � �
确定功率级特性 说明 Type II 补偿 – 电流模式 阐述 Type III 补偿 – 电压模式 补偿电流模式降压 找出交越频率和相位裕量 使用 Excel 补偿器设计工具
2
电源转换器拓扑 Click to edit Master title style
降压 / 正激式
•
降压 / 隔离
升压
•
升压
降压 -升压 / 反激式
•
反转极性 / 隔离
3
电源转换器拓扑 Click to edit Master title style
降压 / 正激式
VI N
L VO U T
VOUT = VIN ⋅ D
24
Type Click II to跨导放大器 edit Master title style
VO U T ′ RF B T VC RC OM P CC OM P CH F RE A gm + VR E F VF B RF B B
环路增益是以反馈环路 为中心的增益， 由误差放大器增益和 功率级增益部分组成。
C om pensatio n
E rror A m p REF
14
理想的控制环路 Click to edit Master title style
80 60 GAIN (dB) 40 20 0 -20
10 100 1,000 10,000 100,000
+
VS L OP E
PW M + VC
-20
-40
A VC ≈
R OUT ⋅ D ′ 2⋅Ri
R OUT ⋅ D′ 2 ωR = L VOUT VSLOPE K m ⋅R i L
-60 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
ωP ≈
2 C OUT ⋅ R OUT
需要充足的相位裕量以避免发生振荡 最佳的相位裕量是 52° 低相位裕量将导致欠阻尼的系统响应 较高的相位裕量则导致过阻尼的系统 响应
•
•
16
功率级回顾 Click to edit Master title style
电压模式降压 电流模式降压 电流模式升压 电流模式降压-升压
17
电压模式降压功率级 Click to edit Master title style
-60 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
ωP ≈
1+ D C OUT ⋅ R OUT
1 ⋅ C OUT
Km ≈
ωZ =
R ESR
ωL =
ˆ OUT v ≈ A VC ˆC v
⎛ s ⎞ ⎛ s ⎞ ⎜ ⎜1 − ω ⎟ ⎟⋅⎜ ⎜1 + ω ⎟ ⎟ R ⎠ ⎝ Z ⎠ ⎝ ⋅ ⎛ s ⎞ ⎛ s ⎞ ⎜ ⎜1 + ω ⎟ ⎟⋅⎜ ⎜1 + ω ⎟ ⎟ ⎝ P ⎠ ⎝ L ⎠
1 ⋅ C COMP
-20 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
ω ZEA =
R COMP
ωHF ≈
1 R COMP ⋅ C HF
ˆC v ˆ OUT ′ v
≈ −A VM
假设 : C COMP >> C HF
ω ZEA s ⋅ s 1+ ωHF 1+
20 MAGNITUDE (dB) 0 -20 -40 -60 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
H( s) =
1 s 1+ ωP
PHASE (°)
45 0 -45 -90 -135 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
VI N
40
L
Logic
VO U T CO U T RO U T
20
A VC
ωP 2⋅π
0 GAIN (dB)
Ri PW M + + +
RE S R
-20
ωL 2⋅π
ωZ 2⋅π
Σ
VS L OP E VC
-40
A VC ≈
R OUT Ri 1 ⋅ R OUT 1 ⋅ C OUT VIN VSLOPE
wenku.baidu.com环路补偿介绍 理想的控制环路 实用的反馈理论
13
环路补偿介绍 Click to edit Master title style
VI N
Pow er Stage : Inductor /Transform er Pow er Sw itches M odulator
VO U T
Load
VC T est Signal
Buck Converter
L
升压
VI N NP NS VO U T
VOUT = VIN ⋅ D ⋅
NS NP
Forward Converter
降压 -升压 / 反激式
4
电源转换器拓扑 Click to edit Master title style
降压 / 正激式
L
升压
VI N
VO U T
VOUT = VIN ⋅
21
误差放大器回顾 Click to edit Master title style
Type I 误差放大器 Type II 误差放大器 Type II 跨导放大器 Type III 误差放大器
22
Type 误差放大器 Click Ito edit Master title style
VO U T ′
ωO =
1 L ⋅ C OUT
FREQUENCY (Hz)
QO =
ωZ = C OUT
R ESR
1 ⋅ C OUT
ˆ OUT v = A VC ⋅ ˆC v
1+
s ωZ
s s2 1+ + Q O ⋅ ωO ωO 2
18
电流模式降压功率级 Click to edit Master title style
VIN
40
L
L o g ic
20
CO U T
A VC
ωP 2⋅π
Ri
RE S R
RO U T
0
-VO U T
ωL 2⋅π
ωR 2⋅ π ωZ 2⋅ π
GAIN (dB)
PW M +
+
-20
Σ
+
VS L OP E VC
-40
A VC ≈
R OUT ⋅ D ′ (1 + D) ⋅ R i
R OUT ⋅ D′ 2 ωR = L⋅D VIN + V OUT VSLOPE K m ⋅R i L
23
Type Click II to误差放大器 edit Master title style
VO U T ′
CH F
40 60
CC OM P RC OM P
RF B T VF B
GAIN (dB) 20
VC
+
A VM ω ZEA 2⋅ π
ω HF 2⋅π
VR E F
RF B B
0
A VM ≈
R COMP R FBT
H( s) =
1 s s2 1+ + QO ⋅ ωO ωO2
PHASE (°)
FREQUENCY (Hz)
90 0 -90 -180 -270
10 100 1,000 10,000 100,000 1,000,000 Q=2 Q=1 Q=0.5 Q=0.25
FREQUENCY (Hz)
12
控制环路基础知识 Click to edit Master title style
VI N
40
L
Logic
VO U T
CO U T RE S R RO U T
20
A VC
ωO 2⋅ π
0 GAIN (dB)
PW M + VR A M P VC
-20
-40
ωZ 2⋅ π
10 100 1,000 10,000 100,000 1,000,000
-60
A VC =
VIN VRAMP
R OUT L
CC OM P RF B T
GAIN (dB) 60
40
VC
+
VF B VR E F RF B B
20
0
-20
ω EA 2⋅ π
-40 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
ω EA =
R FBT
1 ⋅ C COMP ˆC v ˆ OUT ′ v ≈− ω EA s
-60 10 100 1,000 10,000 100,000 1,000,000 FREQUENCY (Hz)
ωP ≈
C OUT
Km ≈
ωZ =
R ESR
ωL =
K m ⋅R i L
ˆ OUT v ≈ A VC ⋅ ˆC v ⎛ s ⎞ ⎛ s ⎜ ⎜1 + ω ⎟ ⎟⋅⎜ ⎜1 + ω ⎝ P ⎠ ⎝ L
1 1− D
Boost Converter
降压 -升压 / 反激式
5
电源转换器拓扑 Click to edit Master title style
降压 / 正激式
VI N L - VO U T
VOUT = VIN ⋅
D 1−D
B u c k -Boost Converter
升压
VI N NP NS VO U T