The Kollmorgen S300 drives can handle this sort of application. They use what's known as 'Wake n Shake' technology that pings the motors with short bursts of current, and then based on the movement, calculates a commutation angle.
I've used them multiple times in encoder-only applications, as well as linear motor applications. They take quadrature or sine-encoder feedback. They're available in 3 Amp continuous / 9 amp peak at 240 VAC.
I can help you size and select one if you provide the right information to me. PM me with the details.
Matt