A Bipolar Voltage Gain Boost AC-AC Converter Based on Four Switching Transistors

Abstract

In numerous applications, such as the correction of grid voltage during voltage sag or swell events caused by system faults, it is necessary to ensure the stabilization of the output voltage with in-phase and out-phase features. This feature can also be employed in high-voltage-gain AC to DC conversion. AC voltage control schemes with one-stage conversion are viable approaches in this regard as only voltage regulation is needed. This conversion approach has strong potential for such applications as it is simple to realize. The voltage-correcting compensators are connected in series with the lines. The inputs of the AC voltage controllers employed in the voltage-correcting compensators may be connected to the faulty phase or other healthy phases. The number of AC voltage controllers used in a voltage compensator are one and two if its input power is drawn from the faulty and non-faulty phases, respectively. In the latter case, voltage gains and phase adjustment are major problems. There is no such issue in the first approach, where the voltage-correcting controller is connected to the line where the voltage variation is to be corrected. A high voltage gain more than the unity of both voltage polarities is required if the depth level of the correcting voltage is around 50% or more. The size and cost of a voltage-correcting controller depend on the number of switching transistors, as an isolated DC source with a gate-controlling circuit is a mandatory requirement for the switching operation of each transistor. Therefore, in the suggested research, an AC voltage controller having bipolar voltage gain is realized only with four switching transistors and six diodes, which reduces the overall size and cost significantly. The verification of the suggested topology is ensured by obtaining the simulation and real results from Simulink-based and practical-based platforms, respectively.

Keywords

• voltage sag
• voltage controller
• voltage gain
• switching transistors
• non-inverting features
• inverting features