A Unified Variable Active Impedance Module with Minimum Power Processing

This letter proposes a unified concept of the active impedance module and its control method with minimum power processing. The impedance value and type of the proposed active impedance module can be adjusted by configuring the control functions. This enables it to operate as a variable capacitor or inductor, supporting both positive and negative capacitance or inductance. The proposed solution addresses the limitations of existing methods in balancing achievable impedance, power processing, and control requirements. The concept, circuit structure, control method, and impedance characteristics are discussed. A self-contained two-terminal prototype without external electrical signals is developed and tested under different application scenarios and conditions. Experimental results verify the feasibility and effectiveness of its functionality.