In today's electronics market, highly efficient DC-DC power converters are in great demand for battery-operated portable electronic devices. Voltage-mode switching power converter is widely used to provide a stable voltage to the portable devices as it has higher efficiency than the current-mode counterpart. Frequency compensation is critical in the controller design as it not only determines the loop gain but also the stability and the dynamic response of the converter. However, the conventional dominant-pole compensation technique only provides a small loop gain crossover frequency and thus results in slow dynamic response....[ Read more ]

In today's electronics market, highly efficient DC-DC power converters are in great demand for battery-operated portable electronic devices. Voltage-mode switching power converter is widely used to provide a stable voltage to the portable devices as it has higher efficiency than the current-mode counterpart. Frequency compensation is critical in the controller design as it not only determines the loop gain but also the stability and the dynamic response of the converter. However, the conventional dominant-pole compensation technique only provides a small loop gain crossover frequency and thus results in slow dynamic response.

In this thesis, a new frequency compensation scheme, which consists of a single-pole error amplifier and a high-pass notch filter in the compensator, is proposed. With the proposed compensation scheme, the loop gain crossover frequency can be significantly increased and thus the dynamic responses greatly improved.

Two hardware prototypes of the buck converters with the conventional and the proposed schemes have been experimentally tested with different output ripple voltages. Measurement results show that the loop gain crossover frequency of the converter with the proposed scheme is 132 times larger than that with the conventional scheme. Under a load step of 400 mA, the maximum output overshoot voltage of the proposed scheme is 4 times less than the conventional one while the transient response of the proposed scheme achieves 93 times improvement. In addition, converters with the proposed scheme under different output ripple voltages give the same loop gain crossover frequency as opposed to different loop gain crossover frequencies obtained from conventional scheme. Thus the robustness of the converter is also improved.