visible light - Limit of human eye flicker perception?

I am designing a LED dimmer using software-controlled Pulse Width Modulation, and want to know the minimum PWM frequency that I must reach to make that LED dimming method indistinguishable from variable DC current.

To dim to X% power, the led will be fully on for X% of the PWM period, and fully off for the rest, with X from 0 to 100. I am assuming that the observer can compare with nearby LEDs driven by DC current at various power (but not exactly X% power), and can move the eye (in particular look at the LEDs in peripheral vision, which, I'm told, is the most sensitive to flicker). I disregard purposefully moving one's head relative to the LEDs, which (I guess) could be an effective distinguishing method; and use of a rotating slit disc or similar technique.

I read movie projectors use 48 or 72 Hz shutter frequency (twice to thrice the frame rate) to reduce flicker to something tolerable (but quite noticeable in peripheral vision, I guess). I also read that the 50 or 60 Hz AC frequency has been chosen to avoid flicker, suggesting that that 100 or 120 Hz flicker is perceptible (but the limit could be much higher, because thermal inertia of the filament must damp variations). Another reference point is that CRT with 100 Hz scan rate have been designed, presumably with some benefit (but again that is not an indication of the upper limit).

Edit: Found this relevant post, Effects of high frequency lighting on human vision

Edit: My LED is "white", that is really blue with a luminescence converter consisting of an inorganic phosphor material.

Answer

You're correct in comparing it to the television refresh frequencies; my brother graduated on flicker research for LED televisions. You indeed need to drive your LED at higher rates. LED TV's do have flicker issues at 60 Hz. In reality, the frequencies involved are even higher: LED TVs used PWM to display intensities in the 0..255 range, by splitting the 1/60'th of a second per frame in parts lasting 1/120th, 1/240, 1/480th,... of a second. (used; some modern TVs now use more complex, less regular schemes that reduce flicker perception).

Another effect that you need to take into account is the phosphors involved in CRT's. The 100/120 Hz models have no flicker issue because the phosphors are designed to glow for milliseconds. Your LED phosphors might not be designed for that; there are quite some different variants around.