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Shu Wu, Yasunori Kobori, Zachary Nosker, Murong Li, Feng Zhao, Li Quan, Qiulin Zhu, Nobukazu Takai, Haruo Kobayashi
A Simple Feed-Forward Controller Design for DC-DC Buck Converter
Dept. of Electronic Engineering, Graduate School of Engineering Gunma University, 1-5-1 Tenjin-cho, Kiryu 365-8515, Japan
Introduction
Feed-forward Controller for DC-DC Buck Converter
Single-Inductor-Dual-Output (SIDO) converter
Proposed Feed-forward Control
Principle
Charge balance of output capacitor
Advantage
Simple
Fast transient response
Cross-regulation improvement
for SIDO buck converter
Research Objective
P72
Summary Simulation
Essential Problem: Transient Response
Conventional Method
Control Delay
during transient response
Complicated
Not cost-effective
• Feed-back control
• Feed-forward + Feed-back control
Digital non-linear feed-forward control
Require accurate modulation
𝑡
𝑡
𝐶𝐿𝐾
𝑉
𝑪𝑳𝑲𝟏 𝑪𝑳𝑲𝟐
𝑻𝒔
1
2
3
DC bias
𝑉𝐼_𝑝𝑒𝑎𝑘 =1
𝑅3𝐶𝐼 𝑉𝑖_𝑐 𝑡 𝑑𝑡𝑇𝑠
0
Current Sensor & Integrator
Multi-period Integration Compensation
Pe
ak
vo
lta
ge
of
sa
wto
oth
--𝑉 𝑃_𝑆
(V
)
Control variable-𝑉𝑐𝑜𝑛 (V)
0
5
10
15
20
25
0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5
Sawtooth Generator
Without feed-forward With feed-forward
Inductor current
Output voltage
SISO Buck Converter
𝑰𝒐: 𝟎. 𝟓𝑨 → 𝟏𝑨
Feed-forward With Without
Under-shoot 5mV 11mV
Response time 8μ s 500μ s
SIDO Buck Converter
Without feed-forward
With feed-forward
Feed-forward With Without
Self-regulation -- 25mV
Cross-regulation -- 30mV
Simple Design:
Only output capacitor current is detected
Digital nonlinear calculation is NOT required
ADC, DSP are NOT required
Applicable to SIDO converter
Cost-effective
Enhanced Performance:
Transient response is significantly improved
Cross-regulation of SIDO converter is improved
Reference 1. Y. Kobori, Q. Zhu, et. al., “Single Inductor Dual Output DC-DC Converter Design with Exclusive
Control”, IEEE Asia Pacific Conference on Circuits and Systems, pp. 436-439, Kaohsiung,
Taiwan, Dec. 2012.
2. S.Y. Chae, B.C. Hyun, W.S. Kim, B.H. Cho, "Digital load current feed-forward control method for
a DC-DC converter”, Applied Power Electronics Conference and Exposition, pp. 498-502,
Austin, TX, USA, Feb 2008.
3. A. V. Peterchev, S. R. Sanders, Load-line regulation with estimated load-current feed-forward
application to microprocessor voltage regulators, IEEE Trans. Power Electronics, vol. 21, no.6,
pp. 1704-1717, Nov. 2006.
𝑰𝒐𝟏: 𝟎. 𝟓𝑨 → 𝟎. 𝟗𝟔𝑨, 𝑰𝒐𝟐: 𝟎. 𝟓𝑨
N-period integrator circuit Timing chart
Compensation method
𝑽𝑰_𝒏𝑻 𝑽𝑰_𝟏 𝑽𝑰_𝟐 𝑽𝑰_𝒏
𝑽𝑰_𝟏
𝑽𝑰_𝟐
𝑽𝑰_𝒏 Sawtooth
Reduction of power loss, volume, cost
Problem: cross-regulation
System Block Diagram
[email protected] [email protected]
Single-Inductor-Single-Output Single-Inductor-Dual-Output
