Twenty-Five Years of Single-Stage Buck-Boost Inverters: Development and Challenges

Single-stage buck-boost inverters have overcome the shortcomings posed by conventional voltage source inverters (VSI) and current source inverters (CSI). VSIs can produce only ac waveforms with a value less than or equal to the applied dc-link voltage (the buck mode), and CSIs can produce only ac waveforms with values greater than or equal to the applied dc-link voltage (the boost mode). On the other hand, single-stage buck-boost inverters can provide a stepped-up/down output voltage, thus accommodating a wide input voltage range. The literature claims single-stage buck-boost inverters are more efficient, less bulky, and able to operate across a wide input voltage range. So why does the industry still love conventional VSIs with a back-ended dc-dc converter or a step-up transformer?