کمینه سازی توان راکتیو در مبدل DC-DC دو طرفه با استفاده از یک پارامتر تک فاز مبتنی بر بهینه سازی ذرات Reactive Power Minimization in Bidirectional DCDC Converters Using A Unified-Phasor-Based Particle Swarm Optimization

I. INTRODUCTION As a key competent of the high-frequency power transmission system, the isolated bidirectional dc-dc converter (IBDC) is essential to achieve a bi-directional power flow and galvanic isolation. The active bridge (DAB) converter is a popular topology of the IBDC converter [1-7]. The conventional control strategy for the DAB converter is named as the phase shift square wave (PSSW) or single phase shift (SPS), which can achieve adjustable transmission power and soft-switching operation by control phase shift between primary and secondary bridge. However, the single control dimension leads to current stress and backflow power, which are uncontrollable and monotonously increasing with the transmission. Especially in the high voltage-conversion-ratio condition, SPS will result in increased reactive power, high current stress and narrower soft-switching region, which finally affect the conversion efficiency [8-12]. The 3-level modulated phase shift control is proposed to solve the demerits of the SPS method. Specifically, the 3- level PWM control can be applied in the primary and secondary bridge to gain an additional control flexibility. It modulates the sequence of switches pairs in the same bridge to create the inner phase shift, which could generate a symmetric 3-level PWM wave in the primary and secondary bridge. Besides, similar as the SPS control, the outer phase shift is implemented between the primary and secondary bridge. Basically, the 3-level modulation can be classified into two cased: one is that the 3-level modulation is adapted only in one bridge, which is called as single-PWM control or extend-phase-shift control (EPS) [13-17]. For instance, the performance of the EPS control is discussed in the [17]. It shows that the 3-level modulated PWM wave can significantly reduce reactive power and extend soft-switching region, which will improve the DAB efficiency for the entire operating range. The other is the 3-level modulation adopted by both primary and secondary bridges. One of this twodimension control is the dual-phase-shift control (DPS), which modulates both sides of the bridge with same inner phase shift angle plus outer phase shift [18]. To further increase the converter efficiency and control flexibility, the dual-3-level modulated phase shift control or triple phase shift control (TPS) is proposed to further increase the converter efficiency [18-22]. It generates inner phase shift in both primary and secondary side, which allows full control of the DAB converter. On this basis, many optimization strategies have been proposed with different objectives to achieve high efficiency of DAB converter for the whole operation range. The power losses model and analysis are reported in [23-25], which shows the major loss of the DAB converter is the conduction loss and it is related to the RMS current.