Optimal Control of Integrated Losses in Dual Active Bridge DC-DC Converters Under Extended Modulation

In order to reduce the overall power loss of the bidirectional active bridge (DAB) converter and optimise its dynamic characteristics; this paper proposes a hybrid optimal control strategy based on the output voltage model predictive control of extended phase-shift modulation and gradient descent algorithm. The state space model of the DAB converter is established by analysing its operating modes under extended phase shift; the switching tube and transformer losses of the DAB converter are investigated to obtain the integrated loss model of the DAB converter; and the output voltage model predictive control is combined with the gradient descent algorithm to optimise the target power loss. Simulation results show that compared with the traditional PI control, the transfer efficiency of the method proposed in this paper is improved by about 3.7%; the dynamic recovery time is reduced by about 80% and the output voltage fluctuation is reduced by about 76% when the input voltage and the load are perturbed, which verifies the effectiveness of the control strategy.