Patent ID: 6958593

Claim:
A power supply apparatus, comprising: a power converter circuit for converting an input voltage from input power supply; an LC filter for smoothing an output of said power converter circuit and supplying the smoothed output to a load; and a controller for controlling said power converter circuit based on an output voltage of the LC filter, and wherein a transfer function (G) of said controller is represented by: N 2 ⁢ s 2 + N 1 ⁢ s + N 0 s 2 + D 1 ⁢ s + D 0 (N0, N1, N2, D0and D1 are coefficients and s is a variable), where a root of a numerator thereof is a real number, and a loop transfer function including a transfer function of said power converter circuit, said LC filter, and said load, and said transfer function (G) of said controller has an open loop characteristic that a gain margin is omitted.