| The non-isolated half-bridge DC/DC converter meets the requirement for electric vehicle and has the advantages of low cost, high efficiency and easy to control. When it needs high current capacity, the interleaved parallel topology is a suitable choice. It reduces the current in each phase and the total current ripple at the same time. In this thesis, the interleaved half-bridge bidirectional DC/DC converter is introduced. After modeling the power stage using a general model, a digital controller with unified control strategy is proposed. The control strategy is verified to have the advantage of smooth bidirectional current flow.To better design the inductor, a deign method combing the optimum of inductor volume index and maximum current is proposed. By reducing the inductor's volume index, a smaller inductor can be realized, which leads to smaller system volume and higher power density. Reducing the maximum current, the converter is easy to design and loss less.Because the two port of a bidirectional DC/DC converter can be either source or load, a general third-order model is proposed. It typifies the resistive load and battery load in one model. When the load is resistive, the third-order model becomes a second-order one, just like traditional buck and boost converter. When the load is an active one, the model can be simplified into a first-order one.The two switches in each phase are controlled in complementary mode. Based on it, a unified controller that could control the two directional current is designed. It could control the average current followihg the positive and negative current command. The system's Bode plot shows the system has sufficient gain and phase margin.Finally, the isolate signal acquisition and conditioning circuits are illustrated. The key point in PCB design is also introduced. The proposed power stage circuit and control method are verified on a prototype. The result shows the proposed structure has reach the target current capacity of 150A and can realize bidirectional current flow. |
