The required peak current and peak voltage of ITER in-vessel vertical stability (VS) coil power supply are up to 80 kA and 2.4 kV, so VS coil power supply needs a pulse width modulation (PWM) rectifier to achieve high power factor operation under the highly transient power demand of the value of 144 MW. A new maximum current control method for three-phase voltage source PWM rectifier based on its mathematical model in d-q frame and improved by dual-closed-loop control method has been presented. This control method meets the fast power charging demand and the dc-side voltage stabilization demand of power supply, and achieves a unity or high power factor operation; its controller is easier to be designed and implemented than dual-closed-loop control at charging mode. The advantages and feasibility of this control method have been verified by simulation and experiment.