Second harmonic current reduction of dual active bridge converter under dual-phase-shift control in two-stage single-phase inverter for residential energy storage system
摘要
The second harmonic current (SHC) generated by the pulsating output power in two-stage single-phase inverters will penetrate to front-end DC/DC converters and the batteries, resulting in decreased system performance. Existing suppression schemes mostly focus on converters operating within a single mode, making them unsuitable for dual active bridge (DAB) converters under dual-phase-shift (DPS) with multiple operating modes. To address these issues, this paper aims to suppress the SHC in the front-end DAB converter under DPS control from an impedance perspective. Firstly, the multi-mode impedance model of the DAB converter under DPS control is derived, revealing the commonality among different modes. Then, a control scheme of virtual impedance introduced into closed-loop impedance (VI-CLI) is proposed, utilizing a unified feedback transfer function for output current. This function consists solely of a PI regulator and a band-pass filter. Moreover, a simplified parameter design approach for the virtual impedance is proposed to minimize the dynamic performance loss while satisfying the SHC suppression requirements. To further enhance the suppression effect, a notch filter is integrated with the VI-CLI scheme to increase the output impedance at twice of the output frequency. Finally, a 1-kVA experimental setup is built to validate the effectiveness of the proposed schemes.
