NON-Microcomputer Ultra Capacitor Charging System

Abstract

The conventional ultra capacitor charger uses computer to monitor the ultra capacitor's state of charge(SOC) and adopts different strategy to charge the ultra capacitor. It makes the system expensive and the control method is also inconvenient. For the above problems, a non-microcomputer ultra capacitor charging system is designed. The proposed system can achieve two-step charging modes, constant current limiting voltage(CCLV) mode and constant voltage limiting current(CVLC) mode. Finally, the designed charging system is presented at the last of the article. The ultra capacitor and its charging characteristic introduction Ultra capacitor is a high-capacity capacitor with capacitance values much higher than other capacitors, but lower voltage limits. It bridges the gap between electrolytic capacitors and rechargeable batteries and stores 10 to 100 times more energy per unit volume or mass than electrolytic capacitors. The ultra-capacitor can charge and discharge much faster than batteries, and tolerate many more charge and discharge cycles than rechargeable batteries. Constant voltage charging is also called as constant potential charging used to maintain the same voltage input to the ultra capacitor throughout the charging process, regardless of the ultra capacitor's state of charge. Constant voltage charging provides a high inrush current to the ultra capacitor because of the higher potential difference between ultra capacitor and charger. The charging curve is shown in figure. 1, a. Constant current charging supplies a relatively constant current, regardless of the ultra capacitor's temperature and state of charge. The charging curve is shown in figure. 1, b.

Development of method for frequency regulation of output current in high-voltage transformerless resonant chargers of capacitive energy storage devices

“…The use of resonant systems with a stabilized output current in CESD charging devices is not new [15,16]. But high-voltage transformers were an integral part of chargers for obtaining high voltage on CESD.…”