Hybrid SPS Control for ISOP Dual-Active-Bridge Converter Based on Modulated Coupled Inductor With Full Load Range ZVS and RMS Current Optimization in DC Transformer Applications

Abstract

The Input-serial-output-parallel (ISOP) dual-active-bridge (DAB) converter is an attractive solution to be used as a DC transformer (DCT) in the DC power distribution system. However, due to zerovoltage-switching (ZVS) limitation and large circulating current, the efficiency of the converter will be reduced. To improve the efficiency, an ISOP DAB converter based on a modulated coupled inductor, and a corresponding hybrid SPS control are proposed in this paper. With the hybrid SPS control strategy, the equivalent leakage inductance of modulated coupled inductor can be controllable. The large inductance is adopted at light load and the small inductance for the transformer is applied at heavy load to reduce circulating current and extend the ZVS range. By optimizing the root-mean-square (RMS) current of two operation modes of the converter, a control boundary of the hybrid SPS control can be obtained to modulate the coupled inductor. Meanwhile, the additional magnetizing inductance is utilized to achieve ZVS for all switches. The analysis based on the RMS current optimization and ZVS condition is given. Based on the conditions of the full load range ZVS and small RMS current, the parameters of the modulated coupled inductor, the turn ratio of the transformer, and magnetizing inductance are designed. Finally, a 250kHz, 800/400V, 2000W ISOP DAB prototype is built to verify the effectiveness of the proposed method. Meanwhile, a comparison experiment with the conventional individual leakage inductors solution is given, which shows performance improvements of the proposed solution.

Research on the Optimal Control Timing of ZVS-QSW

“…Zero-voltage switching quasi-square wave (ZVS-QSW) operation in pulsewidth-modulated dc-dc converters is a wellestablished method for mitigating turn-ON switching losses, because of the constant-frequency operation with low voltage stresses and relatively low current stresses on active devices [1,2]. The ZVS-QSW operation is illustrated in Fig.…”

An Input-Series Output-Parallel DC–DC Converter Based on Fuzzy PID Three-Loop Control Strategy

“…Reference [13] designed an ISOP-DAB converter based on multi-agent deep reinforcement learning, which adopts a control method combining autonomous input voltage balancing and three-phase shift modulation to achieve power balance. Reference [14] designed an ISOP-DAB converter, which includes a modulated coupling inductor and adopts a hybrid SPS control strategy to improve the system's conversion efficiency. Reference [15] adopts an improved input voltage-balancing control strategy to achieve voltage balance of the input capacitor in the ISOP system.…”

Super Twisting Sliding Mode Control Strategy for Input Series Output Parallel Converters

“…Since many signals should be received/sent between master and slave cells, the control strategy limits the modularity and reliability. Similarly, a centralized control strategy is implemented using a single microcontroller [16]. IVS and OCS are achieved with the control strategy that needs to measure the voltages of each cell and ISOP converter.…”

“…• The ISOP connection and super twisting sliding mode control of the isolated current source topology in [8] are introduced first time in this paper. • Compared to [15], [16], [18] and [20], fewer sensor is used for implementing the proposed control method.…”

“…Moreover, the proposed technique doesn't need to transfer cell variables to each other. Therefore, the proposed method is more convenient than the technique in [16]. • Compared to [15] and [16], the modularity is not restricted due to the use of individual microcontrollers for generating PWM signals of each cell.…”