TY - JOUR
T1 - Accurate Loop Gain Modeling of Digitally Controlled Buck Converters
AU - Lin, Jianheng
AU - Su, Mei
AU - Sun, Yao
AU - Li, Xing
AU - Xie, Shiming
AU - Zhang, Guanguan
AU - Blaabjerg, Frede
AU - Feng, Jianghua
PY - 2022
Y1 - 2022
N2 - For the digitally controlled buck converters, the nonlinearity and time periodicity, caused by the pulsewidth modulator (PWM) and sample and hold, make the accurate frequency-domain analysis intractable. In this article, based on the harmonic transfer function (HTF) approach, a precise small-signal continuous-time modeling for the digitally controlled Buck converter operating in continuous-conduction mode (CCM) under constant-frequency voltage-mode control is presented. The sideband components on the closed-loop control are embedded in the model. Thus, this model is accurate within the full frequency domain region, which breaks the limit of Nyquist frequency. Furthermore, by overcoming the barrier of infinite series introduced by the sideband effects, the analytical loop gain expression is derived, which contributes to accurate stability assessment and reduction of computation burden. In addition, the proposed exact small-signal model has explained the reasons why different information injection points lead to different measured loop gains. Simulations and experimental results are conducted to verify the effectiveness of the proposed method.
AB - For the digitally controlled buck converters, the nonlinearity and time periodicity, caused by the pulsewidth modulator (PWM) and sample and hold, make the accurate frequency-domain analysis intractable. In this article, based on the harmonic transfer function (HTF) approach, a precise small-signal continuous-time modeling for the digitally controlled Buck converter operating in continuous-conduction mode (CCM) under constant-frequency voltage-mode control is presented. The sideband components on the closed-loop control are embedded in the model. Thus, this model is accurate within the full frequency domain region, which breaks the limit of Nyquist frequency. Furthermore, by overcoming the barrier of infinite series introduced by the sideband effects, the analytical loop gain expression is derived, which contributes to accurate stability assessment and reduction of computation burden. In addition, the proposed exact small-signal model has explained the reasons why different information injection points lead to different measured loop gains. Simulations and experimental results are conducted to verify the effectiveness of the proposed method.
KW - Digital control
KW - Loop Gain Measurement
KW - Sideband Effects
KW - time periodicity
UR - http://www.scopus.com/inward/record.url?scp=85099723560&partnerID=8YFLogxK
U2 - 10.1109/TIE.2021.3050389
DO - 10.1109/TIE.2021.3050389
M3 - Journal article
SN - 0278-0046
VL - 69
SP - 725
EP - 739
JO - I E E E Transactions on Industrial Electronics
JF - I E E E Transactions on Industrial Electronics
IS - 1
M1 - 9324952
ER -