Digital Pulsewidth Modulation Technique for a Synchronous Buck DC/DC Converter to Reduce Switching Frequency

It has been shown that the resolution of a digital pulsewidth modulator (DPWM) can be dramatically increased by either constant on-time modulation control or constant off-time modulation control as compared to that for constant frequency modulation. However, the switching frequency increases dramatically for the constant on/off-time modulation method under heavy/light load conditions, respectively. The increase of switching frequency results in more switching losses and requires a higher performance controller. The objective of this paper is to propose a new digital pulsewidth modulation (PWM) technique with constant on/off-time control for a synchronous buck dc/dc converter in order to reduce the switching frequency and switching losses. Moreover, the switching frequency can be limited to a certain range. Experimental results of the proposed new digital PWM technique are presented for confirmation. It will be shown that the proposed technique can significantly reduce the switching frequency of the converter, thereby improving DPWM resolution and the efficiency.

[1]  Yen-Shin Lai,et al.  Practical considerations for the design and implementation of digital-controlled power converters , 2010, IECON 2010 - 36th Annual Conference on IEEE Industrial Electronics Society.

[2]  Xiaobo Wu,et al.  High dimming ratio LED driver with fast transient boost converter , 2008, 2008 IEEE Power Electronics Specialists Conference.

[3]  Yen-Shin Lai,et al.  Predictive Digital-Controlled Converter With Peak Current-Mode Control and Leading-Edge Modulation , 2009, IEEE Transactions on Industrial Electronics.

[4]  A. Prodic,et al.  Multibit $\Sigma$–$\Delta$ PWM Digital Controller IC for DC–DC Converters Operating at Switching Frequencies Beyond 10 MHz , 2007, IEEE Transactions on Power Electronics.

[6]  Seth R. Sanders,et al.  Quantization resolution and limit cycling in digitally controlled PWM converters , 2003 .

[7]  Jian Li,et al.  Novel digital multi-phase duty cycle modulation methods for voltage regulators , 2008, 2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition.

[8]  Wei-Hsu Chang,et al.  A Digital boost converter to drive white LEDs , 2008, 2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition.

[9]  D. Maksimovic,et al.  Hybrid Digital Adaptive Control for Fast Transient Response in Synchronous Buck DC–DC Converters , 2009, IEEE Transactions on Power Electronics.

[10]  D. Maksimovic,et al.  Design and Implementation of an Adaptive Tuning System Based on Desired Phase Margin for Digitally Controlled DC–DC Converters , 2009, IEEE Transactions on Power Electronics.

[11]  Li Peng,et al.  A Novel PWM Technique in Digital Control , 2007, IEEE Transactions on Industrial Electronics.

[12]  Yen-Shin Lai,et al.  New Self-Commissioning Digital Power Converter with Peak Current Mode Control and Leading Edge Modulation Using Low Sampling Frequency A/D Converter , 2007, 2007 IEEE Industry Applications Annual Meeting.

[13]  Helen Liu,et al.  Digital Average Current-Mode Control of PWM DC–DC Converters Without Current Sensors , 2010, IEEE Transactions on Industrial Electronics.

[14]  B. Anderson,et al.  Digital control of dynamic systems , 1981, IEEE Transactions on Acoustics, Speech, and Signal Processing.

[15]  Yen-Shin Lai,et al.  Digital controller design for buck converter with the reduction of phase transition and output voltage oscillation under transient state , 2008 .

[16]  Fred C. Lee,et al.  Off-time prediction in digital constant on-time modulation for DC-DC converters , 2008, 2008 IEEE International Symposium on Circuits and Systems.

[17]  D. Maksimovic,et al.  Digital pulse width modulator architectures , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[18]  J. Hung,et al.  Evaluation of DSP-Based PID and Fuzzy Controllers for DC–DC Converters , 2009, IEEE Transactions on Industrial Electronics.

[19]  Murali Munraj.  Digitally Controlled Current-Mode Dc-Dc Converter Ic , 2012 .

[20]  Jian Li,et al.  High Resolution Digital Duty Cycle Modulation Schemes for Voltage Regulators , 2007, APEC 07 - Twenty-Second Annual IEEE Applied Power Electronics Conference and Exposition.

[21]  Yen-Shin Lai,et al.  Online Parameter Tuning Technique for Predictive Current-Mode Control Operating in Boundary Conduction Mode , 2009, IEEE Transactions on Industrial Electronics.