Analysis of Conventional Non-isolated Bidirectional Converters with Smooth Transient Operation

The objective of this work is to achieve a smooth transient operation of non-isolated bidirectional dc-dc converters (BDCs), by implementing two different PWM schemes for transient and steady-state operations, respectively. These two PWM schemes also facilitate the converter operation in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The CCM and DCM modes of converter operation enables efficient control over the bidirectional power flow, especially during low power operation. Apart from this, an equation for average inductor current is derived and validated with active sources on both input and output sides. The analysis of the BDCs has been included using the switch average modeling technique. The operation of the proposed PWM schemes and the expression for the steady-state average inductor current are validated in simulation and hardware. The hardware results are obtained at 1.5 kW output power, with an input voltage of 132 V and an output voltage of 330 V for validating the concept.