Wind power converters need to abide by the Low Voltage Ride-Through (LVRT) demands of grid code during faults, and a reactive-dominated current output is needed according to the sag depth. The output capacity of converter is mainly restricted by junction temperatures of IGBT, for which a temporary enhancement of the reactive capacity is possible. However, the existing LVRT strategies merely consider the rated capacity rather than actual thermal constraints, and only the deepest sag with pure reactive power factor is studied. This paper proposes a full-range thermal-optimal modulation for wind power converter, which is implemented by clamping the vicinity switching intervals to the current peak. Thus, the thermal loss is minimized within the full range of sag depths and power factors. The reactive enhancement of the proposed modulation is also demonstrated by theoretical analysis, and further verified by simulation results.