For $dq$ control strategies in single-phase pulse width modulation (PWM) converters, the $eta-mathbf{axis}$ current must be created by imaginary axis current estimation (IACE) methods.The estimated error of the $eta-mathbf{axis}$ current during the transient process causes $d-q$ axis current loops to be incompletely decoupled, thereby affecting the dynamic performance of the Western pad current loop.The second-order generalized integrator (SOGI) method suffers from slow dynamic response.
The fictive-axis emulation (FAE) method provides fast dynamic response but it is sensitive to circuit parameters.A reference-input (RI)-based IACE method is proposed to overcome the above shortcomings.According to the characteristic that the $eta-mathbf{axis}$ current loop has no transient process, the $eta-mathbf{axis}$ current is estimated by the $d-q$ axis reference inputs.
This is equivalent to introducing the $eta-mathbf{axis}$ reference input as a feedforward term into the $d-q$ axis current loop, so the parameter sensitivity problem is solved, and the parameter tuning is not needed.The proposed method can maintain good steady-state performance and significantly improve the dynamic performance of the current loop.Furthermore, it is straightforward and can be easily implemented in digital controllers.
Comprehensive hardware-in-the-loop (HIL) experimental comparisons with the SOGI and FAE methods have been conducted Knitting Books to verify the correctness and effectiveness of the proposed RI-based IACE method.