To solve the problems of large current stress, difficult soft-switching of all switches, and slow dynamic response of dual active bridge converters, a multi-objective unified optimal control strategy based on triple-phase-shift control was proposed. The forward power flow global modes of triple-phase-shift control were analyzed, and three high-efficiency modes were selected to establish the analytical models of current stress and soft-switching. Combined with these models, the optimal solutions in different modes were derived by using the cost function-optimization equation to overcome the limitation of the Lagrange multiplier method, such that the DAB converter achieved the minimum current stress, and all switches operated in the soft-switching state over the entire power range. At the same time, the virtual power component was introduced in the phase-shift ratio combination, which improved the dynamic response of output voltage under the input voltage or load steps changed by power control. The theoretical analysis and experimental results show that the proposed control strategy can optimize the performance of the DAB converter from three aspects, such as current stress, soft-switching, and dynamic response, which achieves multi-objective optimization of the steady-state and dynamic performance of DAB converters.
LLC resonant converters are widely used in various fields due to high power density and high efficiency. However, when a switch failure happens in LLC, the converter is unable to maintain the normal output voltage gain while achieving high efficiency at resonant point. To make it more compatible with fault occasion, this paper proposes an improved LLC topology that ensures the output voltage remains unaffected when a primary switch failure occurs. Moreover, it can operate near the resonant point, maintaining a high level of efficiency. Additionally, an optimized burst control is added to effectively suppress the overvoltage and oscillation of the resonant capacitor during the fault tolerance transition. Simulation verifies the effectiveness of the proposed method.
Insertion loss (IL) is the main performance index of electromagnetic interference (EMI) filter, and the accuracy of its model directly affects the parameter design of EMI filter. In order to improve the prediction accuracy of insertion loss of EMI filters, accurately describe system behavior and predict EMI filter filtering performance. This paper uses artificial neural network to model the insertion loss of differential mode EMI filters, aiming to provide guidance for the design and optimization of EMI filters.
Aimed at the problems of horizontal misalignment and poor controllability of output power during battery charging,a reconfigurable wireless charging system(WCS)is proposed in this paper.The constant current/constant volt-age charging and zero voltage switching(ZVS)state for a full-bridge inverter are realized through reasonably switching power transmission channels when the mutual inductance and equivalent load resistance vary widely.First,the circuit topology of the system is analyzed,and an expression for the relationship among system parameters,charging current/voltage and ZVS state is derived,thus explaining the rationality of system reconfiguration and power controllability.Sec-ond,a magnetic coupler with sandwich coils(MCSC)is built,and its horizontal misalignment performance is analyzed,which provides a theoretical basis for the design of high misalignment tolerance of the system.Third,the workflow of WCS is analyzed,and a closed-loop controller is designed to realize constant current/constant voltage charging and ZVS state under a wide range of misalignment and load fluctuation.Finally,a WCS for UAV was built,and experimental results show that when the maximum output power was 126 W and the system efficiency was higher than 85%,the horizontal misalignment range was shifted to a circle with a diameter of 340 mm.
In practical applications,the relative position change between the two coupling coils of a wireless power transfer system will change the system parameters,resulting in system detuning as well as a lower power transmission ef-ficiency.For the problem of system detuning,a variable capacitance tuning control strategy is proposed.By controlling the charge and discharge time of the capacitor,the capacitance is equivalent to a variable capacitance,so that the e-quivalent capacitance value and the coil inductive reactance value can meet the resonant condition requirements.As a result,the system is always maintained in a resonant state,and the highest transmission efficiency between the transmit-ting and receiving coils of system will be kept.A simulation model was established,and an experimental prototype of magnetically-coupled resonant wireless power transfer system based on a series-series resonance compensation topology was built.The variable capacitance tuning control experiments were carried out,and experimental results show that the protype can realize stable and reliable wireless power transfer with a resonant frequency of 100 kHz and an input voltage of 20 V,thus verifying the effectiveness of the proposed variable capacitance tuning control method.
