Research On Magnetic Balance Of Dual Active Bridge DC-DC Converter

Dual Active Bridge(DAB)is a popular isolated bidirectional DC/DC converter,which has been widely used in many applications,such as renewable energy generation,electrical vehicle,UPS and so on.Theoretically,the DAB converter has the potential risk of magnetic imbalance,this would increase circuit power loss,affect the normal operation of the converter and even damage devices.Therefore,the research on magnetic balance of the DAB converter has attracted lots of research attention.This paper also foucses on the control method for magnetic balance of the DAB converter.First,this paper analyzes the conventional control method for magnetic balance in a DAB circuit.The most popular method is connecting DC blocking capacitors in series with the transformer primary and secondary windings,which is simple and reliable.However,it increases volume and power loss of the converter and slows down the dynamic response.Furthermore,for high current applications,the DC blocking capacitor would have large load current,this would cause high power loss,and many capacitors should be paralled in order to reach the required current rating,it also increases the volume of the circuit.So it is necessary to find new control method for magnetic balance to further improve the performance.In order to overcome the disadvatges of the conventioanl magnetic balancing method for the DAB converter,this paper proposes a new control method for the magnetic balance.The proposed method is based on hysteresis control.By slightly tuning the duty cycle of power transistors in the primary side,the magnetic balance of the transformer can be achieved.Finally,a DAB bidirectional DC/DC converter is designed and hardware implemented along with a simulation model.The simulation and experimental results verify the proposed control method.