Switched-capacitor Based Seven-level Boost Inverter with a Reduced Number of Devices

Abstract

The conventional multilevel inverters (MLIs) have the disadvantages of numerous devices, incapacity of boost, unbalance for capacitor's voltage, high complexity for control, and etc. Motivated by this issue, a seven-level boost inverter (7LBI) based on a switched capacitor is presented for single-phase applications in this paper. The proposed 7LBI using only seven transistors can achieve seven output levels, 1.5 voltage gain, and natural balance of capacitors' voltages without sensors or other auxiliary methods, which illustrates its suitability for the applications of renewable energy generation. The configuration of topology and operating principles are illustrated in detail. The natural balance of capacitors and capacitance calculations are deduced as well. Moreover, the comparative study is conducted for different types of MLIs. The results illustrate the merits of the proposed 7LBI with respect to reduced devices, lower voltage stress, and less power loss. Finally, a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis; an experimental prototype is also implemented, verifying multilevel output, boost ability, natural balance for switched capacitors, and performance of transient response.

Keywords

• Multilevel inverters
• voltage gain
• natural balance
• renewable energy generation
• reduced number of elements