Research On Optimal Control Strategy Of Dual Active Bridge

As a high efficiency bidirectional DC-DC converter topology, Dual Active Bridge(DAB) has many advantages such as wide input and output range, easy control, constant operating frequency and low current stress, and so on. Only rely on the parasitic parameter, the converter can make sure all of the switches operate in ZVS and obtain a high efficiency. Nowadays, it is widely used in electric vehicle, microgrid, super capacitor energy storage system, new energy power generation, etc.In order to reduce the power loss of the converter, an optimal control strategy with combined dual-phase-shift and traditional-phase-shift control is proposed. It can minimize the RMS current while realizing ZVS and wide input and output range. By combining the EPS and SPS, the converter can operate in the whole load range. Combined with the existing control strategy, the proposed control strategy is easy to realize ZVS and reduce loss. Meanwhile, a closed loop control is easy to realize.The control mode and control strategy are first presented. Depending on the analysis included, a current stress control stategy is stated. The main characteristics, including the transmission power, ZVS range, and current stress, are analyzed and an optimal control trajectory of the RMS current, transmission power, and soft switching conditions is derived, which enables the DAB converter to operate in the minimum-RMS-current state while guaranteeing ZVS operation of all power switches. Thus, both the conduction and switching losses can be significantly reduced. Finally, simulation is conducted and a experimental protype is built to validate the correctness of theoretical analysis and feasibility of the control strategy.