Power Balance Control Based on Sensorless Parameters Estimation for ISOP Three-Level DAB Converter

The dual active bridge (DAB) converters offer high-power density and bidirectional transfer capabilities. The input series output parallel (ISOP) modular DAB converters are commonly used for isolated medium/high to low voltage conversion. To address the power unbalance problem caused by the differences among modules in the ISOP-DAB converter, this article proposed a sensorless power balance control method based on parameters estimation (SPBCM-PE) that does not require additional voltage/current sensors, additional auxiliary circuits, or specific system parameters. Compared to existing power balance methods for ISOP-DAB, the proposed load-independent method is compatible with multimodule converters and does not require load parameters, eliminating the need for real-time dynamic estimation. It is considered the balance of both the modules’ input voltage and output current. To validate the proposed SPBCM-PE, this article designed a 220 V–24 V ISOP-DAB experimental platform with a neutral point clamped half bridge–full bridge topology and significant differences between modules. In the power range of 10–435 W, the experiments showed that the proposed method significantly improved input voltage and output current balance compared to the traditional method with system efficiency ranging between 87.2% and 94.3%. Overall, the proposed balance method offers an effective solution for achieving power dynamic balance in the full power range.