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A single-phase two-switch SEPIC AC to DC converter is proposed in this paper. The boosting supply of the input is controlled by PWM of the power stage, while the desired DC output is PWM controlled. Since both the input boost supply and the output supply can be controlled independently, a fast transient response can be maintained at both the input for active current wave shaping and at the output for good output regulation. In addition, independent control of the multiple outputs provides the strong decoupling necessary and hence good transient response. Finally, some experimental results are presented for verification.

A high performance three-phase active power filter is proposed in this paper. A novel circuit for detecting the amplitude of the active part of the fundamental load current is also proposed. The detection time of the current is not more than 1/4 cycle. Its transient response is superior to the other conventional techniques. Moreover, the proposed algorithm avoids the use of mains voltage signal in the calculation of reference compensation current. Therefore, the mains current after compensation still has a purely sinusoidal waveform even when the mains voltage is distorted. In addition, a simple control scheme, based on the energy balance concept, is proposed to control the voltage of an energy-storage capacitor. Because the energy change in the energy-storage capacitor can be fast compensated, a small energy-storage capacitor is required. The advantages of the proposed active power filter are low cost, small size and fast transient response. Finally, some simulation results are presented for verification. Keywords-active power filter; energy balance; energy-storage capacitorI.

A fast power factor detector for nonlinear loads is proposed to overcome the drawback of conventional detectors, which can measure only the power factor of linear loads. The design of the proposed detector is based on the concept of additional characteristic of trigonometric function. It does not require any low-pass filter or integrator. Therefore, the transient response of the proposed detector is much faster than that of the conventional detectors. The theoretical response time of the proposed detector is less than one-fourth of a cycle. Because of its promising accuracy and rapid transient response, it can be used in many systems such as the control of power systems, and active power filters, to improve their transient performance. Theoretical analysis and experimental results are also detailed in this paper.

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