Rapidly developing household energy storage systems raise the demand for corresponding DC-DC converters. Although topologies like LLC have already achieved good performance in these large-power and wide-voltage-range applications, they still have shortcomings in dealing with low-voltage battery cells. When converting from low voltage to high voltage, conventional methods can hardly control output current well when the normalized voltage gain is greater than one. Moreover, they cannot ensure a constantly small turn-off current on the low-voltage side over various working conditions, which affects efficiency and stability. To overcome these drawbacks, the paper proposes a hybrid strategy combining frequency and phase modulation for LC resonant converters. First, the theoretical model of the proposed method is constructed and analyzed. Second, a circuit is built and the proposed method is implemented, which is subsequently tested at different working conditions. As the experimental result, the actual output current is close to the expectation and the turn-off current is nearly a small constant at all the working conditions. Hence, the proposed modulation strategy is verified to solve those drawbacks. Furthermore, based on this method, close-loop output current and voltage controller will also be easier to design.

The continuous-control-set model predictive control (CCS-MPC) has been proven as a suitable multi-input multi-output (MIMO) control method for the Multi-Active-Bridge (MAB) converter. It can improve the dynamic response, minimize the cross-coupling effect inherently, and simplify the controller design. However, the constraints on the phase shift angle of the MAB converter are inevitable and have not been addressed in the existing CCS-MPC scheme. To overcome this issue, this paper proposed a CCS-MPC method for MAB converter that considers the phase shift constraints. The optimization problem is formulated based on the predictive model and then converted to a standard quadratic programming (QP) problem with phase shift constraints. The optimization package OSQP is employed for solving the constrained QP problem. The effectiveness of the proposed control method is validated through simulation and experiment.

Multi-Active-Bridge (MAB) converter has complex power flow control requirements, which can be tackled by the continuous-control-set model predictive control (CCS-MPC) method. This controller has a simple and extensible design procedure, exhibiting excellent dynamic performance and in-tuitive parameters, without requiring decoupling consideration. However, the inevitable digital delay can reduce the phase margin and negatively impact its dynamic performance. To overcome this issue, this paper introduces a delay compensation mechanism that alters the execution sequence of control actions. The modified system model, predictive law, and control law under this mechanism are derived. The effectiveness of this method is validated by simulation. The influence of weighting factors is also analyzed to present a controller design guidance.

As the renewable power sources increase their penetration in power systems, the proper schedule and control for battery storage systems have become an urgent problem. In this paper, we proposed a new system framework for multi-port energy router-based battery pack active balance system. Three ports of the energy router are serially connected so that the power can flow among each battery pack to balance state of charge. Besides, the power level of the system is expanded due to this topology. A hierarchical power schedule strategy is proposed to form a comprehensive energy management in schedule layer, control layer, and driver layer. Simulation results show the effectiveness of the proposed framework and control strategy.

Multi-port AC-coupled converter (MAC) is promising to become the next-generation energy router in future Micro-grid and energy Internet to satisfy the upcoming requirement. As the most critical component of MAC, the multi-winding transformer needs a suitable model to achieve power flow analysis and flexible control. This paper analyzes the multi-winding transformer model suitable for MAC application. Three existing transformer modeling methods have been investigated, i.e. self-/mutual-inductance matrix, extended T model, and extended cantilever model. Their equivalent conversions to the expected model have been derived. A four-port multi-winding transformer is designed for the Multi-Active-Bridge converter. The experiment and simulations are performed to compare the advantages and disadvantages of three transformer models.