Single phase utility interactive Switched Boost Inverter for renewable energy based residential power applications

Switched Boost Inverter (SBI) is a single stage power converter that can generate a dc output and an ac output simultaneously from a single dc input voltage source. Unlike the traditional buck type Voltage Source Inverter (VSI), the SBI can produce an AC output voltage that is either greater or less than the available DC input voltage. Other advantages of SBI when compared to the VSI include (a) tolerance to shoot-through in the inverter phase legs, (b) robust EMI noise immunity, and (c) no dead-time requirement. These features make the SBI suitable for stand-alone and utility connected residential power applications supplied from renewable energy sources such as solar panel or fuel cell. This paper presents the DSP based closed loop control of a single phase utility connected SBI supplying a 250 W DC load while injecting 250 W active power into the grid at unity power factor. The grid synchronization of SBI is achieved using a Second Order Generalized Integrator (SOGI) based Phase Locked Loop (PLL) and the grid current regulation is done using Synchronous Reference Frame (SRF) approach. The closed loop control strategy has been implemented in digital domain using TMS320F28335 Digital Signal Processor (DSP). The DSP based closed loop control strategy is also verified using a 500 W experimental prototype of single phase utility connected SBI. The experimental results presented in the paper show good correlation with the theoretical analysis.