A Triple Voltage Boost Frontend Hybrid T-Type Converter

This paper proposes a triple boost frontend three-phase hybrid T-type converter (HT
²
C) configuration and its modulation strategy. The HT
²
C is formed by adding a half-bridge cell and split capacitors to an existing three-level T-type converter. It can generate improved power quality waveforms with four-level output voltage on the ac side when operated with medium to higher modulation indices. The DC side voltage boost and balancing configuration facilitate integration of low voltage source like solar PV, fuel cell, or battery with a voltage equal to one-third of the total DC-link voltage. A new space vector pulse width modulation (SV-PWM) for HT
²
C is proposed that utilizes only three voltage vectors in each switching cycle to approximte the reference vector. A computationally efficient algorithm is developed to find the desired voltage vectors and their duty ratios from any conventional SV-PWM with little modification. The proposed configuration is tested experimentally for various operating conditions. The results demonstrate the effective capacitor voltage balancing with boosting capability and improved performance on the ac side of the converter. A split capacitor arrangement along with a TRIAC can also enable three-level operation of HT
²
C if and when required.