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This paper presents a buck‐boost PWM power inverter and its application for the residential photovoltaic system. The PWM power inverter is realized by driving an inverter constructed with a high‐frequency buck‐boost chopper in the discontinuous conduction mode (DCM). The photovoltaic system with the power inverter has the following advantages: (1) the power generated by the photovoltaic array can be transferred to the load and the utility line under any array voltage; (2) isolation between the photovoltaic array and the utility line is performed by a small high‐frequency reactor operating as energy storage element; (3) there is no need of a reactor to link the utility line; (4) unity power factor operation is provided; and (5) the system configuration is very simple. the input‐output characteristics of the system are analyzed. As a result, the ripple component of the array current and the power flow between the interface and the utility line are derived and verified experimentally.

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This paper presents analysis of a high‐power factor ac‐dc converter with a boost converter operating in the discontinuous conduction mode (DCM) and the critical conduction mode (CRM). The converter can be expressed by a nonlinear differential equation for each mode. The equation in DCM is solved analytically by separating its variable (output voltage) into two terms of a ripple component and a direct component, and by linearizing the equation for the ripple component. On the other hand, the equation in CRM can be solved analytically. Furthermore, the source current waveform of the converter is expanded into the Fourier series. As a result, the output voltage, its ripple and the power factor of the converter in DCM and CRM are derived as a function of the circuit parameters, respectively, and verified experimentally. These equations exhibit clearly the effect of each circuit parameter of the converter and the difference between the converter in DCM and in CRM. The converter operating in CRM produces sinusoidal ac current with unity power factor.