Model Predictive Control of Dual Active Bridge DC-DC Converter based on PWM plus TPS Modulation for Automotive Applications

The dual active bridge (DAB) converters are mostly used in automotive application where bidirectional power flow is required to reduce weight of the power system. This converter is affected by variations in output voltage requirement, input voltage fluctuations and changes in load. Therefore, it is necessary to improve performance of converter. The current stress of the dc-dc converter must be optimized in order to improve the efficiency. This can effectively reduce converter losses. Authors propose Model Predictive Control (MPC) based on PWM plus triple phase shift (TPS) modulation to improve dynamic performance, as well as to maintain output voltage level of DC-DC converters. Due to simplicity of implementation PWM has combined with triple phase shift method to expand zero voltage switching (ZVS) range, minimizes the circulating current and conduction losses, reduce current stress, reduces EMI interruption. The control function is developed to minimize the difference between the reference voltage and the actual output voltage by controlling the phase shift between the primary and secondary H-bridges of DAB converter in order to maintain the constant output voltage. Simulation results are presented to verify the merits of the model predictive control based on PWM plus triple phase shift modulation technique which includes a soft switching, fast dynamic response, constant output voltage over a wide operating range, reduced current stress, increased efficiency of the DAB converter which has been evaluated under the conditions such as step changes in reference voltage, input voltage fluctuations and changes in load.