Implementation and control of Switched Boost Inverer for DC nanogrid applications

Switched boost inverter (SBI) is a single stage power converter that can supply both dc and ac loads simultaneously. 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. Also, the SBI exhibits better EMI noise immunity when compared to the VSI. These features make the SBI suitable for microgrid and nanogrid applications. In this paper, the SBI is proposed as a power electronic interface in DC nanogrid. The structure and advantages of the proposed SBI based DC nanogrid are discussed in detail. A closed loop control system is also designed for the SBI supplying both DC and AC loads using Synchronous Reference Frame (SRF) approach, and it is implemented in digital domain using Texas Instruments TMS320F28335 Digital Signal Processor (DSP). The control system of SBI has been experimentally validated using a 0.5 kW experimental prototype of SBI supplying both DC and AC loads, and the relevant experimental results are presented in the paper. The experimental results show that the DSP based control system shows excellent performance under the steady state as well as during the transients in either DC or AC loads in the system. The low cross regulation of the control system has also been verified for a step change in either DC or AC load of SBI. These experimental results confirm the suitability of the SBI and its closed loop control strategy for DC nanogrid applications.