Power Applications Lab
DIEET
i&pdivision
industrial & power conversion
A novel linear-non-linear digital
control for DC/DC converters
DIEET – Università di Palermo
Ing. Valeria BOSCAINO
Ing. Giuseppe Maria DI BLASI
Ing. Patrizia LIVRERI
Prof. Ing. Giuseppe CAPPONI
http://www.dieet.unipa.it/labep
[email protected]
Riunione Annuale GE 2006
I&PC Division – STMicroelectronics
Ing. Filippo MARINO
Ing. Marco MINIERI
Ischia, 21-23 giugno 2006
Main features
 Multiphase system
 Digital control
 PWM control technique
 Voltage-Positioning (AVP)
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Four module interleaved buck
converter
 Input Voltage:
 12V
 Output Voltage:
 1V
 Output Current:
 0-120A
 Maximum Output Voltage Ripple
30mV during transient
2mV at steady state
 Switching frequency
250kHz/phase
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Single phase linear control loop
Current-sharing
comparator
Riunione Annuale GE 2006
Adaptive voltage
positioning
Ischia, 21-23 giugno 2006
VREF
VOUT
4
Q4
Q3
Q2
Q1
4
ADC
Switching
Logic
Phase 1
PWM1
VC1,i
VC2,1
CS1
DAC
PWM2
VC1,1
VC2,2
CS2
DAC
PWM3
Switching
Logic
Phase 3
VC1,2
VC2,3
CS3
DAC
PWM4
VC1,3
VC2,4
Switching logic
DAC
according to interleaved technique
Riunione Annuale GE 2006
COMP_OUT
VC2,i
Switching
Logic
Phase 2
Switching
Logic
Phase 4
AVP
ADC
4
4-module
step-down
converter
VDC
COMP
CS4
VC1,4
Ischia, 21-23 giugno 2006
Non linear control: items
 Fast transient response to load
changes
 No over- and under-shoots in
regulated output voltage during
transient
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Non linear control
Vin=12V
MULTIPHASE
DC/DC
CONVERTER
OUTPUT
VOLTAGE
NON LINEAR
CONTROL
LINEAR
CONTROL
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Non linear control action
Increasing load current
Riunione Annuale GE 2006
Decreasing load current
Ischia, 21-23 giugno 2006
Non linear control: main advantages
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Recovery time reduction by 25% up to 40%.
Output voltage over- and under- shoots reduction by
50% up to 65%.
Non linear control active only during a load transient
 Unaffected steady-state operation.
Unchanged converter topology.
Possible applications on any dc/dc converter topology .
AVP compatible.
System bandwidth independent from that of the linear
control loop.
Solved limit-cycle problems.
Non linear action dependent only on output voltage.
Easy implementation.
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006