This paper offers a two-stage boost converter for a single-phase inverter without transformer for PV systems. Each stage of the converter is separately controlled by a pulse width modulated signal. A Simulink model of the converter using efficient voltage control topology is developed. The proposed circuit performance characteristics are explained and the obtained simulation results are confirmed through the applied experiments. Moreover, this paper has examined the control circuit of a single-phase inverter that delivers a pure sine wave with an output voltage that has the identical value and frequency as a grid voltage. A microcontroller supported an innovative technology is utilized to come up with a sine wave with fewer harmonics, much less price and an easier outline. A sinusoidal pulse width modulation (SPWM) technique is used by a microcontroller. The developed inverter integrated with the twostage boost converter has improved the output waveform quality and controlled the dead time as it decreased to 63 µs compared to 180 µs in conventional methods. The system design is reproduced in Proteus and PSIM Software to analyze its operation principle that is confirmed practically.

In this paper, a new control strategy for an induction motor (IM) drive system fed from three-phase pulse width modulation (PWM) ac chopper is proposed. The main objective of the proposed control scheme is to achieve input power factor correction (PFC) of the IM drive system under different operating conditions. PFC is achieved by continuously forcing the actual three-phase supply currents with the corresponding reference currents, which are generated in phase with the supply voltages, using hysteresis band current control (HBCC) technique. The proposed control strategy has two loops: the inner loop and outer loop. The output of the outer loop is the magnitude of the supply reference current resulting from either speed controller or startup controller, whereas the output of the inner loop is PWM signals of the ac chopper. The proposed ac chopper features a smaller number of active semiconductor switches, four IGBTs, with only two PWM gate signals. As a result, the proposed system is simple, reliable, highly efficient, and cost effective. Mathematical analysis of the drive system is presented. Components of the input LC filter are designed using frequency response. The IM drive system is modeled using MATLAB/SIMULINK, and a laboratory prototype was built and tested. The simulation and experimental results confirm the validity and robustness of the proposed control strategy. INDEX TERMS Hysteresis band current control, induction motor drive, power factor correction, pulse width modulation, three-phase AC chopper.

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Reducing the number of active switches is substantial for obtaining a simple, reliable, highefficiency, and cost-effective AC/AC voltage converter. In this paper, two topologies of three-phase direct PWM AC/AC voltage converter are proposed. The first is for the buck converter and the other is for the boost one. Each converter has no DC energy storage elements and employs only three IGBTs. The proposed converters do not use lossy snubber circuits and have not commutation problems. A simple, reliable, and cost-effective control strategy, which employs only one voltage sensor, is also proposed. Using a closedloop voltage control technique, two complementary PWM gate signals are generated to drive the three active switches of each converter. Adjusting the duty ratio of PWM gate signals regulates the output voltage of the AC/AC converters. Operating principle and mathematical analysis of the converters are presented. Voltage stresses across active and passive semiconductor switches of the proposed converters are derived. Small signal analysis based on complex DQ transformed equivalent circuits of the converter is introduced. Voltage controller design using frequency response analysis is provided. The converters are simulated using MATLAB/SIMULINK and laboratory prototypes are implemented in real-time using DSP-DS1104 control board. The converters are tested under different operating conditions and their performances are investigated and compared. The symmetry of the output voltage/current is examined by the theory of symmetrical components. The simulation and experimental results are in a close agreement. This confirms the validity of the theoretical analysis, the effectiveness of the control strategy, and the feasibility of the proposed converters.INDEX TERMS AC-AC voltage converters, control design, small signal analysis, stability analysis, symmetrical components, voltage stress.