ScholarWorks@경상국립대학교

초록

A direct thyristor AC/AC converter is configured as a 3-phase 4-wire type to be used in an eco-friendly and efficient far-infrared paint drying system. Additionally, the zero-crossing-based switching scheme is proposed in the paper for the output power control in detail according to temperature-power relationship. A direct thyristor AC/AC converter with a simple and economical converter connection structure is suitable for this application. The phase control for thyristor AC/AC converter has a negative impact on the power system by producing harmonic currents depending on the conduction angle adjustment, and a problem of incurring additional costs exists due to the application of filters. Zero-crossing control of a conventional 3-phase 3-wire thyristor AC/AC converter has the disadvantage of large range of change in output power. To minimize this problem, the paper introduces the topology of a 3-phase 4-wire thyristor AC/AC converter based on zero-crossing control scheme to minimize the generation of harmonics in the input current and segment the output power. PLL algorithm is applied to detect the phase information of the grid voltage, and a power calculation method based on d-q coordinate transformation considering the absent current generated by the proposed switching combination is presented. Following a switching combination control technique based on zero crossing control that can be controlled according to the temperature/power relationship, arbitrary 3-phase, 2-phase, 1-phase operation and no-output states are controlled for logical feasibility through PSIM simulation analysis. The effectiveness is also proven by confirming the harmonic distortion reduction through experimentation.

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