where igd is the sinusoidal current reference for the rectifier to follow. It is also to be noted that the reference current is in phase with the input voltage so unity power factor is achieved and I gdm is the peak value of the reference current. The amplitude of the reference current is formed by a linear controller. Since at this stage a DC error signal generates the reference amplitude it is possible to perfectly track the reference signal with a PI controller. The DC error signal is formed as,