Single inductor dual buck-boost inverter based on half-cycle PWM scheme with active clamping devices

Abstract

This paper presents a single-phase differential-type photovoltaic inverter named single inductor dual buck-boost inverter (SIDBBI) based on improved half-cycle PWM (HPWM). Conventional DBBI (CDBBI) is a good option for photovoltaic application due to step-up/down ability for varying inputs. However, inherent high inductor current and corresponding increments of inductor size and device ratings have made it less attractive than other topologies. This paper proposes an HPWM scheme with active clamping switches to reduce inductor voltage swing, highly induced current and component stresses by eliminating output voltages offsets. Under the proposed modulation, component voltage stresses in CDBBI can be reduced by zero offset, and there arises a chance to integrate half-utilized inductors, main switches and complementary diodes of two modules into one set, which is the proposed SIDBBI topology. 500 W prototypes of the conventional/proposed inverters have been built for verifications and comparison. Detailed analysis and experimental results under the proposed HPWM show that the size of SIDBBI can be reduced by 40.4% than CDBBI, maintaining comparable efficiency over 96% and wide input coverage by step-up/down ability. Comparative results address that SIDBBI is competitive in terms of component counts, stresses and losses, compared with various kinds of buck-boost inverter topologies.