Single-Phase AC-DC-AC Multilevel Five-Leg Converter Based on a High-Frequency Transformer

Cardoso, Jean T.; Jacobina, Cursino B.; Rodrigues, Phelipe L. S.; Lima, A.M.N.

doi:10.1109/tia.2023.3288513

Cited by 1 publication

(2 citation statements)

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“…It is inefficient to use such converters as voltage controllers. Some of the deficiencies of the indirect AC–DC–AC are tackled by applying the multilevel approach, as discussed in Refs 6 , 7 . The converter in Ref 6 is a five-level, and its operation is based on the use of a high-frequency transformer.…”

Section: Introductionmentioning

confidence: 99%

“…The converter in Ref 6 is a five-level, and its operation is based on the use of a high-frequency transformer. In Ref 7 , three modules with two DC link capacitors are employed, and the problem of floating capacitors is tackled. All indirect AC-to-AC converters suffer from circuit complexity, an increase in overall volume, high cost, and low conversion efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Design and implementation of an innovative single-phase direct AC-AC bipolar voltage buck converter with enhanced control topology

Ashraf,

Abbas,

Mushtaq

et al. 2024

Sci Rep

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Direct AC–AC converters are strong candidates in the power converting system to regulate grid voltage against the perturbation in the line voltage and to acquire frequency regulation at discrete step levels in variable speed drivers for industrial systems. All such applications require the inverted and non-inverted form of the input voltage across the output with voltage-regulating capabilities. The required value of the output frequency is gained with the proper arrangement of the number of positive and negative pulses of the input voltage across the output terminals. The period of each such pulse for low-frequency operation is almost the same as the half period of the input grid or utility voltage. These output pulses are generated by converting the positive and negative input half cycles in noninverting and inverting forms as per requirement. There is no control complication to generate control signals used to adjust the load frequency as the operating period of the switching devices is normally greater than the period of the source voltage. However, high-frequency pulse width modulated (PWM) control signals are used to regulate the output voltage. The size of the inductor and capacitor is inversely related to the value of the switching frequency. Similarly, the ripple contents of voltage and currents in these filtering components are also inversely linked with PWM frequency. These constraints motivate the circuit designer to select high PWM frequency. However, the alignment of the high-frequency control input with the variation in the input source voltage is a big challenge for a design engineer as the switching period of a high-frequency signal normally lies in the microsecond. It is also required to operate some high-frequency devices for various half cycles of the source voltage, creating control complications as the polarities of the half cycles are continuously changing. This requires at least the generation of two high-frequency signals for different intervals. The interruption of the filtering inductor current is a big source of high voltage surges in circuits where the high-frequency transistors operate in a complementary way. This may be due to internal defects in the switching transistors or some unnecessary inherent delay in their control signals. In this research work, a simplified AC–AC converter is developed that does not need alignment of high-frequency control with the polarity of the source voltage. With this approach, high-frequency signals can be generated with the help of any analog or digital control system. By applying this technique, only one high-frequency control signal is generated and applied in AC circuits, as in a DC converter, without applying a highly sensitive polarity sensing circuit. So, controlling complications is drastically simplified. The circuit and configuration always avoid the current interruption problem of filtering the inductor. The proposed control and circuit topology are tested both in computer-based simulation and practically developed circuits. The results obtained from these platforms endorse the effectiveness and validation of the proposed work.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%