Diode-Assisted Buck–Boost Voltage-Source Inverters

This paper proposes a number of diode-assisted buck-boost voltage-source inverters with a unique X-shaped diode-capacitor network inserted between the inverter circuitry and dc source for producing a voltage gain that is comparatively higher than those of other buck-boost conversion techniques. Using the diode-assisted network, the proposed inverters can naturally configure themselves to perform capacitive charging in parallel and discharging in series to give a higher voltage multiplication factor without compromising waveform quality. In addition, by adopting different front-end circuitries, a number of diode-assisted inverter variants can be designed with each having its own operational principle and voltage gain expression. For controlling them, a generic modulation scheme that can be used for controlling all diode-assisted variants with minimized harmonic distortion and component stress is first designed, before proceeding on to design a second scheme with minimized commutation count for complement. All theoretical findings discussed in the paper were verified experimentally using a number of scale-down laboratory prototypes with relevant results presented in a later section for visual confirmation.