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The main contribution of this paper is to present a simple algorithm that theoretically and numerically assesses the switching angles of an inverter operated with the SPWM technique. This technique is the most widely used for eliminating harmonics in DC-AC converters for powering motors, renewable energy applications, household appliances, etc. Unlike conventional implementations of the SPWM technique based on the analog or digital comparison of a sinusoidal signal with a triangular signal, this paper mathematically performs this comparison. It proposes a simple solution to solve the transcendental equations arising from the mathematical analysis numerically. The technique is validated by calculating the total harmonic distortion (THD) of the generated signal theoretically and numerically, and the results indicate that the calculated angles produce the same distribution of harmonics calculated analytically and numerically. The algorithm is limited to single-phase inverters with unipolar SPWM. [ABSTRACT FROM AUTHOR]

This paper presents an igniter circuit for high-intensity-discharge (HID) lamps based on an inverter and a resonant tank that has been adapted to stabilize inductively an HID lamp by means of applying low-frequency quasi-square waveforms to voltage and current in the lamp in order to reduce the presence of the acoustic resonances. With the proposed improvement, the igniter circuit performs three different functions: 1) the lamp ignition; 2) the arc stabilization; and 3) the acoustic resonances reduction. This proposal allows the use of fewer components, and less energy processing is minimized, so the resulting ballast is cheaper and more efficient than other ballast that avoids the acoustic resonances when they are working with square waveforms in the lamp voltage and current. The circuit was validated experimentally by using a 70 W conventional high-pressure sodium lamp, which is operated with a frequency of 2 kHz. The results were an electrical efficiency of 94%, a crest factor in the lamp current of 1.41, and it was not observed the presence of acoustic resonances. [ABSTRACT FROM AUTHOR]

The arrangement of the full-bridge, current-source inverter as a power supply for ozone generators providing high power factor (PF) and high electrical efficiency in a single stage is the main contribution of this paper. The corresponding design, simulation, and experimental results are presented. Also, the use of the current-fed, full-bridge resonant inverter for PF correction in ozone generation applications is discussed. The proposed power supply consists of an ac supply, a single rectifier bridge, an input inductor to the inverter, four switches, an LC parallel resonant tank, a resonant transformer, and a set of ozone generating cells. Experimental results with the proposed topology provided 96% for PF, 91% for electrical efficiency, and ozone production of 614 mgO3/min, satisfying the requirements of the standard 61000-3-2, class A. [ABSTRACT FROM AUTHOR]

This paper is aimed to report the consequences in the use of the well-known bootstrap technique in single-phase current-fed full-bridge resonant inverters (SPCFFBRIs) operating with and without reactive energy. Based on both simulations (using the PSPICE software) and experiments it is shown that this technique is not feasible for this type of inverters when the load is predominantly reactive. The bootstrap technique conveniently operates when the load is purely resistive or resonant. The unfeasibility in the use of the bootstrap technique with reactive or nonresonant loads comes from the fact that the load voltage is applied to the bootstrap capacitor and, consequently, to the gate of the floating MOSFET, producing an imminent damage both in the control circuit and in the floating MOSFET. Therefore, other alternatives for feeding the floated MOSFETs must be considered. [ABSTRACT FROM AUTHOR]

In this paper, the analysis and design methodology of a high-frequency self-oscillating (SO) electronic ballast with lamp current control are presented. SO electronic ballasts have two important drawbacks: First, the lamp current varies according to the ac input voltage, causing undesired effects in the lamp brightness, and second, the design method lacks precision at very high frequency operation (greater than 200 kHz) mainly due to the Cgs parasitic capacitance. The ballast is modeled by using the descriptive function method and the extended Nyquist criterion; the model of the ballast includes a control circuit and takes into account the high-frequency effect of the MOSFET parasitic capacitance Cgs. Finally, experimental results of a 38-W SO electronic ballast prototype with lamp current control for high-intensity discharge lamps are presented to validate the analysis and the proposed methodology. The switching frequency is selected at 2 MHz in order to avoid the acoustic resonance problem. [ABSTRACT FROM AUTHOR]

The cascade multilevel inverters are widely used in industrial manufacturing processes for DC-AC conversion. Therefore, the reliability and efficiency improvement, optimized control, and fault-tolerant strategies are areas of interest for researchers. The fault tolerance strategies applied to cascade multilevel inverters are classified as material redundancy and analytical redundancy. This paper presents the use of the Z-source converter as a fault reconfiguration method applied to a cascade multilevel inverter. On the one hand, the proposed approach has the characteristic of combining the use of material redundancy (modifying the output voltage by changing the Z-source operation), and on the other hand, it has the use of analytical redundancy (modifying the switching sequence of the multilevel inverter, changing from symmetrical to asymmetrical operation mode). This approach has been validated by experimental results of the system under fault-free conditions and employing the Z-source converter as the main fault reconfiguration element. The proposed fault reconfiguration strategy allows the cascaded multilevel inverter to continue to operate even in the presence of a fault by having continuous operation. [ABSTRACT FROM AUTHOR]