Abstract
The modeling of losses at differential inverters is becoming crucial, especially for enhancing efficiency and reliability of their DC-DC modules. Losses modeling based on sinusoidal duty cycle, at line frequency F-L, without considering differential inverters characteristics and switching frequency (F-S) of their DC-DC modules is not accurate, needs high computational demand, and is not applicable for different PWM modulation schemes. In this paper, a simple and accurate losses modeling for differential inverters is proposed based on two-stage calculation process. In first stage, the losses is calculated based on the switching frequencies for DC-DC modules F-S. Then, in the second stage, the losses is averaged according to operating frequency of differential inverters F-L. The decoupling between both frequencies facilitates the easy insertion of differential inverters characteristics such as static linearization approach and low order even harmonics. Also, it easily obtains the RMS currents in terms of module parameters which reduce the required computational calculations. The proposed modeling is applicable for most modulation schemes such as SVMS, CMS and DMS, thanks to the decoupling property of proposed losses modeling. It is generic for single-phase, three-phase, and multi-phase differential inverters and thoroughly supported efficiency improvement even at modular differential inverters. The flow chart of the presented methodology is explained in detail and effectively applied for many DC-DC modules. For verification, a differential inverter based on SEPIC modules is introduced to validate the accuracy of the proposed losses modeling.