An output voltage (Vout1) of an active filter circuit (10), which boosts and smoothens a direct-current voltage (Vin), is converted into an alternating-current voltage by means of an inverter circuit (20). The active filter circuit (10) is equipped with a capacitor (Cdc) and a rectifying component (11S) that are connected between input and output parts. Additionally, the active filter circuit has an inductor (L1) that is connected to the input part at one end with the other end being connected to the output part via the rectifying component (11S), a switching component (12S) that is connected between the other end and a low-potential side line, and a first control circuit (30) for the switching component. The inductor (L1) stores energy when the switching component (12S) is closed, and discharges the energy when the switching component (12S) is opened. The rectifying component (11S) conducts electricity in the direction the energy stored in the inductor (L1) is discharged. Consequently, an inverter device that is capable of sufficiently suppressing rippling of an input voltage to the inverter device without requiring a large-capacity smoothing capacitor can be provided.

This paper proposes a new circuit configuration and a control scheme for a single-phase current-source inverter with a power decoupling circuit which is called as the active buffer. The proposed inverter achieves a low-dc-input voltage ripple and also provides a sinusoidal current that can achieve unity power factor, without large passive components in the dc bus such as smoothing inductors and electrolytic capacitors. These components are conventionally required in order to decouple the power pulsation caused by the single-phase power source. In this paper, the fundamental operations of the proposed inverter are demonstrated experimentally. From the experimental results, the input voltage ripple is 8.87%, and the output current total harmonic distortion is 4.24%. In addition, an output power factor of 99% and a maximum efficiency of 94.9% are obtained. Finally, it is confirmed that the maximum power densities of the conventional circuit and the proposed circuit are 2.75 kW/L at the switching frequency of 70 kHz and 4.86 kW/L at the switching frequency of 80 kHz, respectively.

This paper discusses a new circuit configuration and a new control method for a single-phase ac-dc converter with power factor (P.F.) correction and a power pulsation decoupling function. The proposed converter can achieve low total harmonic distortion (THD) on the input current and the power pulsation decoupling function between the input and output sides, which allows low output voltage ripple even on a small output energy buffer at the same time using an active buffer. Therefore, the proposed converter does not require large smoothing capacitors or large smoothing inductors. The buffering energy is stored by a small capacitor, which controls the variation of the capacitor voltage through the active buffer. In this paper, the fundamental operations of the proposed converter are investigated experimentally. The experimental results reveal that the input current THD is 1.44%, the rate of the output voltage ripple is 6.33%, and the input P. F. is over 99%. In addition, a maximum efficiency of over 96% is obtained for a 750-W prototype converter.

This paper proposes a space vector modulation scheme for a new single phase to three phase power converter that using an active buffer. The proposed circuit is based on the control theory of an indirect matrix converter which can successfully reduce the volume of the smoothing capacitor in the DC link part. The proposed circuit needs to control the output voltage and the buffer current at the same time. In order to reduce the output voltage and the input current harmonics； a space vector modulation scheme is proposed. In this paper； the basic operation of the proposed method is confirmed by experimental results. The input current THD and the output current THD around the fundamental component frequency are 3.34%and 6.65%； respectively. Moreover the capacitor current THD in the input filter and the output voltage THD that is below than 15 kHz switching frequency are improved by 10%and 17%because the switching waveforms becomes symmetrical shape. The validity of the proposed method is confirmed with these results.