A Novel Discretization Method for Multiple Second-Order Generalized Integrators

Multiple second-order generalized integrators (MSOGI) has been widely used to extract the signal that contains multiple harmonics. The MSOGI needs to be implemented in the discrete-time domain for its practical applications. More critically, the discretization method can greatly affect its performance. The existing discretization methods for MSOGI can be divided into three categories: entire transfer-function discretization, SOGI-transfer-function discretization, and integrator discretization. The theoretical analysis indicates that the first method can avoid the errors caused by unit delay, but it is hard to be digitally realized for high-order transfer functions. The other two methods have nonnegligible errors in both the phase and the quadrature characteristic due to the unit delay. In this letter, we propose a novel discretization method by modifying the structure of integrator discretization. This method can enhance the performance in both the phase and the quadrature characteristic with an acceptable computation burden, which has been theoretically analyzed and experimentally verified.