Automatic dead time optimization in a high frequency DC-DC buck converter in 65 nm CMOS

AbstractThe typical power-assisted hip exoskeleton utilizes rotary electrohydraulic actuator to carry out strength augmentation required by many tasks such as running, lifting loads and climbing up. Nevertheless, it is difficult to precisely control it due to the inherent nonlinearity and the large dead time occurring in the output. The presence of large dead time fires undesired fluctuation in the system output. Furthermore, the risk of damaging the mechanical parts of the actuator increases as these high-frequency underdamped oscillations surpass the natural frequency of the system. In addition, system closed-loop performance is degraded and the stability of the system is unenviably affected. In this work, a Sliding Mode Controller enhanced by a Smith predictor (SMC-SP) scheme that counts for the output delay and the inherent parameter nonlinearities is presented. SMC is utilized for its robustness against the uncertainty and nonlinearity of the servo system parameters whereas the Smith predictor alleviates the dead time of the system’s states. Experimental results show smoother response of the proposed scheme regardless of the amount of the existing dead time. The response trajectories of the proposed SMC-SP versus other control methods were compared for a different predefined dead time.

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A Current-Mode Four-Phase Synchronous Buck Converter with Dynamic Dead-Time Control

IEEE Access ◽

10.1109/access.2021.3085826 ◽

2021 ◽

pp. 1-1

Author(s):

Jun Tang ◽

Tian Guo ◽

Jung Sik Kim ◽

Jeongjin Roh

Keyword(s):

Dead Time ◽

Current Mode ◽

Buck Converter ◽

Time Control ◽

A Current

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Stacked Buck Converter: Current Ripple Elimination Effect and Transient Response

Energies ◽

10.3390/en14010064 ◽

2020 ◽

Vol 14 (1) ◽

pp. 64

Author(s):

Chien-Chun Huang ◽

Yu-Chen Liu ◽

Chia-Ching Lin ◽

Chih-Yu Ni ◽

Huang-Jen Chiu

Keyword(s):

Transient Response ◽

Dead Time ◽

Control Method ◽

Buck Converter ◽

Modulation Method ◽

Output Current ◽

Time Modulation ◽

Advantages And Disadvantages ◽

Improvement Method ◽

Current Ripple

To balance the cost and volume when applying a low output current ripple, the power supply design should be able to eliminate the current ripple under any duty cycle in medium and high switching frequencies, and considerably reduce filter volume to improve power density. A stacked buck converter was eventually selected after reviewing the existing solutions and discussing their advantages and disadvantages. A stacked buck converter is used as a basis to propose the transient response and output current ripple elimination effect, boundary limit control method, and low output ripple dead time modulation method to make individual improvements. The principle, mathematical derivation, small-signal model, and compensator design method of the improvement method are presented in detail. Moreover, simulation results are used to mutually verify the correctness and effectiveness of the improvement method. A stacked buck converter with 330-V input, 50-V output, and 1-kW output power was implemented to verify the effect of the low output current ripple dead time modulation. Experimental results showed that the peak-to-peak value of the output current ripple was reduced from 2.09 A to 559 mA, and the RMS value was reduced from 551 mA to 91 mA, thereby effectively improving the output current ripple.

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