• Title/Summary/Keyword: valance value

Search Result 2, Processing Time 0.016 seconds

Study and Recovery on the Capacity Loss after the Long Charge-discharge Operation of VRFB-ESS (장시간 충방전에 따른 VRFB-ESS의 용량 손실 회복에 대한 연구)

  • Hai-Kyung, Seo;Wonshik, Park;Jae-woo, Park;Kangsan, Kim;Hansol, Choi
    • KEPCO Journal on Electric Power and Energy
    • /
    • v.8 no.2
    • /
    • pp.181-187
    • /
    • 2022
  • As the charges/discharges of VRFB-ESS were repeated during 150cycles or more, the capacity of electrolyte in VRFB-ESS was decreased little by little. It results from the decreasing of the level of anolyte and the increasing of the valance value of the catholyte. Then, we tried to recover the capacity loss with 3 different ways. The first way was that the levels of anolyte and catholyte were allowed to be evenly equalized when the difference in the levels of two different electrolytes were severe. The second one was to lessen the valance value of the catholyte through the reduction reaction to 4-valant ions of 5-valant ions in the catholyte with the reductant, oxalic acid. The last one was that the all electrolytes of analyte and catholyte were allowed to be electro-chemically reduced to 3.5 of the valance value by oxidizing new electrolyte with 3.5 valance ions. The last way was the most effective to recover the capacity loss.

A Study on High Performance Operation of Hybrid Energy Recovery Drive System for Piezoelectric Pump (피에조 펌프 구동용 에너지 회수형 하이브리드 구동장치 고성능 운전에 관한 연구)

  • Hong, Sun-Ki;Lee, Jung-Seop;Cho, Yong-Ho;Kim, Ki-Seok;Kang, Tae-Sam
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.64 no.10
    • /
    • pp.1426-1431
    • /
    • 2015
  • Piezoelectric pump can be considered as R-C load and it needs something special driver because the output voltage does not become 0 even though the applied voltage is 0 with common converter. This operating system consists of fly-back converter to increase the input voltage and energy recovery inverter to apply square voltage to the piezoelectric pump. The energy recovery inverter can charge and discharge the energy of capacitive load. In this paper, to enhance performance of the driver, a few elements or circuits are added and modified. To drive the inverter safely, current limit resister is added and adjusted the value to valance the charging and discharging current. In addition, a current limit inductor is added to the input side to limit the input current and enhance the efficiency. Inductor only may make oscillation and another resister is added parallel to the inductor to solve this problem. The converter and inveter are assembled to one board for compactness. The appropriateness is proved with simulation and experiments.