| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系所 === 101 === This thesis presents an integrated energy management system for Li-ion battery and super-capacitor. The proposed system integrates a super-capacitor charging module and a Li-ion battery charging module, and adds a DC/DC boost converter as the post-regulator for Li-ion battery. The energy distribution via the micro-controller management to make up Li-ion battery for higher load status to extend the Li-ion battery life. The proposed energy management system associated with the control strategy can distribute the output energy required for load situation, especially the abruptly varied load.
The controller for Li-ion battery is LTC4052 manufactured by Linear Technology (LTC), wherein the familiar multi-stage constant current charging (MCC) method and pulse charging method both are used. The controller for super-capacitors to achieve voltage balance charging is LTC4425. The PWM controller TPS61222 by Texas Instruments (TI) is used for the boost converter. The micro-controller dsPIC33FJ06GS202 by Microchip is utilized as the control core of entire system. The used micro-controller detects current through and voltages across the Li-ion battery and super-capacitors, and performs the implemented control program to achieve the proposed control strategy for energy management system to distribute the required energy even under the abrupt load variances.
Li-ion battery takes advantages of high energy density, high operation voltage and non-memory effect. The advantages of super-capacitor includes high power density, long life, excellent charge and discharge speed, and a wide range of operating temperature. The specification of the used Li-ion battery is 3.7 V/350 mA, the rated capacity is 1.295 Wh and super-capacitor specifications is 2.5 V/3.3 F. Besides charging and discharging control for both Li-ion battery and super-capacitor, the control strategy proposed in this thesis programs Li-ion battery as the primary source to load, that is, in normal operations, energy is supplied to load by Li-ion battery. Additionally, the control method connects super-capacitor to Li-ion battery with parallel both as the power source for the abrupt load situation if necessary. For charging balance control between the super-capacitors, an existing IC is used to achieve equal voltages across individual super-capacitor.
The design specifications are as follows : the input voltage is 5.5 V, the maximum input current is 1 A, the output constant current is 270 mA, and the output voltage of DC/DC converter is 5 V. Finally, the experimental results verify correctness and feasibility of the proposed circuit structure and control strategy.
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