A recently proposed circuit D-Q transformation is used to analyze a three-phase controlled-current PWM rectifier. The de operating point and ac transfer functions are completely determined. Most features of the converter are clearly interpreted. They are 1) the output voltage can be controlled from zero to maximum, 2) the system is equivalently an ideal current source in the steady state, 3) the system can be described as linear circuits, and 4) the input power factor can be arbitrarily controlled within a certain control range.