A switched-capacitor and floating-capacitor (SCFC) based multilevel boost inverter with a single DC power supply and sensor-less voltage balancing method

Abstract

This paper introduces a nine-level (9L) boost inverter with reduced number of components. The proposed 9L topology comprises a single DC source, eight switches, and two capacitors, namely a switched-capacitor (SC) and a floating capacitor (FC). The topology consists of two converter units: the SC unit and the FC unit. Both units are cascaded to achieve nine voltage levels with a voltage gain of 2. The inherent voltage boosting capability of the proposed topology makes it suitable for low-scale voltage applications like photovoltaics (PV) and electric vehicles (EVs). A sensorless method is introduced to stabilize the requisite voltage across the FC for any undesirable changes in input voltage. The performance reveals that the voltage across the FC does not deviate with changes in the modulation index, power factor of load, pulse width modulation (PWM) methods, or the operating frequency. And, when the input voltage fluctuates, the voltage across the FC is naturally adjusted to the new desired value within 0.6 s. The topology operates over a wide range of modulation indices (0 to 1) and different types of loads. A generalized topology is also developed to get a high output voltage along with a higher number of intermediate voltage levels. A comprehensive analysis is presented to show the effectiveness of the proposed topology over the recent topologies.