| Ultracapacitor, which has the advantages of high specific power, high charging speed, long cycle life and non-pollution to the environment, is a novel green energy storage device, and it has vast potential for future development. Due to its low rated voltage, which usually ranges from 1 to 4 volts, ultracapacitor needs to be connected in series to get high voltage in most occasions. However, the discreteness of parameters of ultracapacitors, causing the imbalance of capacitor voltages, will shorten the lives of some capacitors and affect the stability of the system, on the other hand, the output voltage of the system will drop obviously especially when the system is discharging in large current, and that usually affects the load working conditions. As a result, it is necessary to maintain the balance of voltages between ultracapacitors and keep output voltage smooth.First of all, some common voltage balancing methods are discussed and compared through simulation in the article. Then we choose the DC-DC converter voltage balancing method according to actual requirement and make it simple. A novel simplified DC-DC converter voltage balancing method is proposed. After analysis in simulation, we use this simplified DC-DC converter method as the final voltage balancing method.To make output voltage of the system smooth, we choose the boost DC-DC converter system, which is based on MC34063, as the final voltage-stabilizing plan. Then the designing idea and schematic diagram of this method is proposed.The design and construction of hardware circuit is discussed in the end. The proposed methods of voltage balancing and voltage stabilizing are proved feasible through analysis of experimental data.
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