| Hybrid electric vehicles (HEVs), which owns power sources of both engine and battery, has a distinct advantage on fuel economy and exhaust emission characteristics. Because the battery provides traction power to assist the engine and recycle the regenerative braking energy when HEV decereases. The bidirectional DC/DC converter is applied in HEVs power electronic control unit to control the bidirectional energy flow. Bidirectional DC/DC converter’s mode swap anc control strategy is studied in this paper.Firstly, the state of bidirectional DC/DC converters applied in HEVs and the state of mode swap and control are reviewed. Basic bidirectional buck/boost converter is selected to study mode swap and control in this paper according to bidirectional DC/DC converter’s technical specifications such as input voltage, output voltage, etc. Different operation modes in corresponding with HEVs diverse conditions are analyzed and working principles in different operation modes are explained. Parameter designs of main circuit and protection logic designs are given afterwards.Then, Control targets of converter’s different operation modes are analyzed and established to meet application needs of HEVs. Then small-signal dynamic models of the converter under different operation modes are derived and corresponding controllers parameters are also designed in detail to improve the overall system performance. Based on theoretical design, the experimental verification of the converter’s steady-state and dynamic performances under different operation modes are given in the following paper.Finally, the converter’s mode swap strategy is analyzed and established. And the single mode swap and total mode swap experimental verification has been conducted in a5kW basic bidirectional buck/boost converter experimental platform and the human-computer interaction interface which is developed to simulate the manager computer. |
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