The Study Of The Control Strategy For Three-port Bi-directional DC-DC Converter

With the increasing of imbalance load and continuous improvement of power quality for power equipments, negative-sequence current balancing is becoming more and more serious. This thesis proposed a new negative-sequence current balancing method based on three-port bi-directional DC-DC converter as well as its control strategy.The method can achieve active power exchanging among three-phase power grid to improve the problem of three-phase imbalance effectively through the three-port bi-direction DC-DC converter. The three-port bi-directional DC-DC converter plays an essential role in achieving power exchanging and galvanic isolation among the three-phase power grid. The problem of three-phase imbalance phenomenon can be effectively improved through the three-port bi-direction DC-DC converter.The operation principle, system capacity, and relation of energy transfer among the three-port bi-directional DC-DC converter have been analyzed in detail.The control strategies of three-port bi-directional DC-DC converter as well as negative-sequence current balancing system were proposed in this paper. At the same time, the mathematical model of control strategy was derived. A 220V/2kW prototype was designed and constructed and tesed. Mean while, the important influence to negative-sequence current balancing system of the high frequency isolation transformer parameters was analysis according to the experimental results, which provided an important basis for system overall debugging and improvement. KEYWORDS:Three-port Bi-directional DC-DC Converter; Control Strategy; Negative Sequence Balancing; Power Transmission; Mathematical Model...