| 摘要 |
A filter circuit is provided for two-axis signals which has good filtering characteristics such as steep filter characteristics in a narrow bandwidth without transformation from a stationary coordinate system into a rotating coordinate system and vice versa. Input signals related to orthogonal two axes are represented by a complex variable (U=Ux+jUy: Ux, Uy are respective quantities of Laplace transformation), and a transfer function of a lowpass or highpass filter of real coefficients is represented by F(s). A complex coefficient transfer function produced by replacing the Laplace operator "s" in the transfer function F(s) with "s-jomega" is represented by F(s-jomega). When the input complex variable U is passed through the complex coefficient transfer function F(s-jomega), an output signal related to orthogonal two axes is expressed by a complex variable (V=Vx+jVy: Vx, Vy are respective quantities of Laplace transformation), and a transfer representation equation is expressed by U F(s-jomega)=V. Connections are made with a transfer element of real coefficients in order to equalize real and imaginary parts of the transfer representation equation after both sides of the transfer representation equation are multiplied by the denominator of F(s-jomega).
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