To deal with a command of step load change for a dual-active-bridge converter, a transient current control with a multi-phase-shift gating scheme is needed. By selecting a reference signal with a floating position, the effective transient current control can be achieved by moving multiple voltage edges in sequence, which would fulfil the step transition of the load level in a fast and smooth manner. Although the analysis is derived using triple-phase-shift schemes, the proposed control can also be applied to other multi-phase-shift schemes, such as extended-phase-shit and dual-phase-shift scheme. An experimental test validated the correctness and effectiveness of the proposed transient current control.

An energy storage system (ESS) plays an important part in a renewable energy generation system for stable and efficient power harvesting. To realize the function of an ESS, a bidirectional DC/DC converter with high power density and high efficiency is highly desired. In this paper, a high-frequency (HF) isolated dual-bridge series resonant converter (DBSRC) with a piecewise control strategy is proposed for an application with a wide variation of voltage gain. The proposed control strategy is based on dual-phase-shift modulation for a balance between complexity and flexibility. With this proposed control strategy, zero-voltage switching is kept for all switches on the low-voltage side and half of switches on the high-voltage side. Besides, there is no circulation energy on the low-voltage high-current side for full load operation. A step-by-step design procedure is also included to calculate the converter components and control parameters. Verification of the analysis and design are performed successfully through simulation and n experimental test. Comparisons with some existing control methods are also made experimentally, which highlights that the proposed control strategy is able to achieve comparable performance as the reported optimal current control with simpler calculation and implementation.

We aim to explore the associations between matrix metalloproteinase (MMP) MMP-2/MMP-9 gene polymorphism with ulinastatin (UTI) efficacy in treating severe acute pancreatitis (SAP). A total of 276 SAP patients were assigned into the control (n=135) and observation (n=141) groups. PCR-restriction fragment length polymorphism (PCR-RFLP) was used for genotype and allele frequency distribution. Relevance of MMP-2/MMP-9 genotypes with UTI efficacy was analyzed. The observation group showed lowered duration in symptoms (abdominal distension, abdominal pain, tenderness, and rebound tenderness) than the control group. Laboratory analysis (serum calcium, white blood cells, serum amylase, urine amylase, APACHE-II, and Balthazar CTIS scores) were decreased, while serum albumin levels increased after 7th day of therapy. The total effective rate of UTI for patients with MMP-2 C-1306T C/C genotype was higher than those with C/T and T/T genotypes after the 7th day of therapy, which was lower in patients with MMP-9 C-1562T C/C and C/T genotypes than those with T/T genotype. The duration for symptoms in patients with MMP-9 C-1562T T/T genotype was shorter than those with C/C and C/T genotypes, which was less in patients with MMP-2 C-1306T C/C genotype than those with C/T and T/T genotypes. The improvement values of APACHE-II and Balthazar CTIS scores for patients with MMP-2 C-1306T C/C genotype were higher than those with C/T and T/T genotypes, which for patients with MMP-9 C-1562T C/C and C/T genotypes were lower than those with T/T genotype. These results demonstrated that MMP-2/MMP-9 gene polymorphism was associated with UTI efficacy for SAP.

The procedure of load transition in a dual-active-bridge converter is expected to be fast and spike free. To achieve such a goal, the total required adjustment of phase-shift angles should be assigned to different switch arms properly. This study discusses all possible combinations of two switch arms and their related phase-shifts, which could result in several different solutions. By forcing a zero algebraic variation of the volt-second product, all solutions can keep the volt-second balance of the power inductor so that no risk of magnetic saturation in the transient state exists. The possibility of temporal overshoot current can be checked by verifying the monotonicity of the intermediate volt-second product. A comparison of all solutions is made to give a suggestion for their feasibility. Experimental tests are included at last which validated the theoretical analysis.

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A secondary phase-shifted dual-bridge converter with semi-active rectifier is able to perform buck-boost dc-dc conversion with soft-switching. However, it can not maintain zero-voltage switching (ZVS) operation for all switches in a wide load range. Besides, the root mean square/peak tank current increases inversely with the decreasing of load in the light load region. To alleviate these problems and extend its load range, a hybrid varying-frequency phase-shift (VFPS) control is proposed to manipulate the power for a semi-dual-bridge converter with the primary half-bridge and secondary semi-active rectifier topology. Steady-state analysis of the converter under VFPS control is performed using the fundamental harmonic approximation approach. A detailed design procedure is given then to find a full ZVS trajectory with a fixed ZVS margin at light load. Experimental results proved that the VFPS control can effectively extend the operation range with full ZVS and maintain high efficiency at light load for the semi-dual-bridge resonant converter.

In this paper, the triple-phase-shift (TPS) control with certain unified boundary conditions is applied to a dual-bridge series resonant converter (DBSRC) for applications needing bidirectional energy flow ability. The control strategy is unified for the whole variation range of load, input/output voltage and with simple calculation. By using this unified boundary control, the circulating energy is minimized significantly. A wide soft switching operation range can be achieved as well. Furthermore, based on the analysis results of unified boundary conditions, an improved unified boundary control with duty cycle compensation is also proposed. The ZVS operations of all sides switches can be maintained for wide converter gain and load with high efficiency. The procedure of design for important parameters is given. Finally all works are verified through actual experimental tests on a 500W laboratory prototypes successfully.

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