TY - JOUR
T1 - Approximate Discrete-Time Small-Signal Models of DC-DC Converters with Consideration of Practical Pulsewidth Modulation and Stability Improvement Methods
AU - Li, Xin
AU - Ruan, Xinbo
AU - Xiong, Xiaoling
AU - Sha, Mengke
AU - Tse, Chi K.
N1 - Funding Information:
Manuscript received February 13, 2018; revised April 27, 2018 and July 12, 2018; accepted July 31, 2018. Date of publication August 9, 2018; date of current version March 29, 2019. This work was supported by the National Natural Science Foundation for Distinguished Young Scholars under Award 51525701. Recommended for publication by Associate Editor S. Kapat. (Corresponding author: Xinbo Ruan.) X. Li, X. Ruan, and M. Sha are with the Center for More-Electric-Aircraft Power System, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China (e-mail:, [email protected]; [email protected]; [email protected]).
Publisher Copyright:
© 1986-2012 IEEE.
PY - 2019/5
Y1 - 2019/5
N2 - It is generally known that averaged models are inadequate in describing the effects of leading-edge and trailing-edge pulsewidth modulation (PWM) on the stability of dc-dc converters. In this paper, using discrete-time models of the buck, boost, and buck-boost converters and considering the effects of leading-edge and trailing-edge PWM, the general expressions of the duty-cycle-to-output-voltage transfer function, G vd (z), in the discrete-time domain are derived. Based on the low-pass characteristics of the dc-dc converters and related properties of the matrix functions, approximate expressions of G vd in the frequency domain are derived, which are simple and accurate up to half the switching frequency. Using the approximate G vd , the stability of the three basic dc-dc converters under leading-edge and trailing-edge PWM is analyzed. It is shown that the stability of the buck converter is unaffected by the type of PWM, while the leading-edge modulated boost and buck-boost converters have better stability than the trailing-edge modulated ones. Since the trailing-edge modulation is commonly available in PWM controller integrated circuits, the modulation signal zero-order holding (ZOH) method and the inductor current feedback control method are proposed for use in the trailing-edge modulated boost and buck-boost converters to achieve the same effect of leading-edge modulated converters. Experimental buck and boost converters were constructed for verification of the accuracy of the proposed model and the validity of the proposed control schemes.
AB - It is generally known that averaged models are inadequate in describing the effects of leading-edge and trailing-edge pulsewidth modulation (PWM) on the stability of dc-dc converters. In this paper, using discrete-time models of the buck, boost, and buck-boost converters and considering the effects of leading-edge and trailing-edge PWM, the general expressions of the duty-cycle-to-output-voltage transfer function, G vd (z), in the discrete-time domain are derived. Based on the low-pass characteristics of the dc-dc converters and related properties of the matrix functions, approximate expressions of G vd in the frequency domain are derived, which are simple and accurate up to half the switching frequency. Using the approximate G vd , the stability of the three basic dc-dc converters under leading-edge and trailing-edge PWM is analyzed. It is shown that the stability of the buck converter is unaffected by the type of PWM, while the leading-edge modulated boost and buck-boost converters have better stability than the trailing-edge modulated ones. Since the trailing-edge modulation is commonly available in PWM controller integrated circuits, the modulation signal zero-order holding (ZOH) method and the inductor current feedback control method are proposed for use in the trailing-edge modulated boost and buck-boost converters to achieve the same effect of leading-edge modulated converters. Experimental buck and boost converters were constructed for verification of the accuracy of the proposed model and the validity of the proposed control schemes.
KW - Discrete-time model
KW - leading-edge modulation
KW - pulsewidth modulation (PWM)
KW - stability
KW - trailing-edge modulation
KW - zero-order hold
UR - http://www.scopus.com/inward/record.url?scp=85052590025&partnerID=8YFLogxK
U2 - 10.1109/TPEL.2018.2864924
DO - 10.1109/TPEL.2018.2864924
M3 - Journal article
AN - SCOPUS:85052590025
SN - 0885-8993
VL - 34
SP - 4920
EP - 4936
JO - IEEE Transactions on Power Electronics
JF - IEEE Transactions on Power Electronics
IS - 5
M1 - 8432117
ER -