Estudo e desenvolvimento do controle de tensão de um retificador monofásico com compensação ativa de ondulação de baixa frequência utilizando capacitores de alta durabilidade para alimentação de leds

Abstract

Regarding technology advances, static converters have gained prominence over their longevity, targeting applications that require a more durable power supply, such as LED lighting, for example. In these devices, the lower desired voltage ripple level, the greater capacitance value, imposing the use of electrolytic capacitors, whose useful life is lower in comparison to the other elements. Currently, there are numerous alternatives for solving this problem, but the limitations are diverse due to the costs and ripple levels. This work aims the development of the voltage control of the conversion stages of a single-phase rectifier with active compensation coupled to a LC filter and a buck converter, respectively, used to power a load consisting of 160 LEDs, totaling 288 𝑊. The topology is designed and modeled in state space considering the simplified model of a light emitting diode and is designed to reduce capacitances, maintaining low levels of voltage and current ripples in the load, thus allowing the use of high durability capacitors. Three closed-loop control systems are designed, in addition to the open-loop control, in order to perform a comparative study in terms of the power factor and harmonic content. With the classic PI controller, the voltage ripple levels obtained in the two steps meet specifications and are lower than 5.02%, with a power factor equal to 0.743 and THD of the input current equal to 77.29%, while for the other cases the variations are greater than 5.88%. The capacitance values used are equal and less than 50 𝜇𝐹 and the variation of the current supplied to the LEDs is about 6.4%. For a full-bridge rectifier to achieve the same levels at the first stage output, a capacitance of 216 𝜇𝐹 would be required. However, there is no complete compliance to the IEC 61000-3-2, standard for lighting equipment. Simulations waveforms and other results are presented in order to validate this study.