Phosphor-converted（PC）white LEDs have relative fixed spectral structures, with much blue spectrum but less red and green components. As a result, their correlated color temperature (CCT) is difficult to adjust and generally high, accompanied by an insufficient color rendering index (CRI). For this reason, tunable white LED systems are constructed based on spectral compensation, which improves the spectral continuity and uniformity in the visible light range, thus to obtain the dynamic tunability of CCT and enhancement of CRI. Combined with the photo-electro-thermal characteristics analysis of LED devices, a nonlinear dynamic relationship model of CCT is established. This model allows for quick prediction of CCT for the mixed spectra under given electric driving states, and in reverse enabling driving control according to target CCTs. In verified experiments, the nonlinear dynamic relationship model of CCT can accurately predict CCTs with errors of no more than 4.5%. In terms of dimming for target CCTs, errors between actual CCTs and their target ones are less than 1.5%, with CRI upgrade rates exceeding 5% and even reaching up to 18.51%. All the experiment results suggest that spectral compensation is a feasible approach to optimize the spectral structure of PC white LEDs, in this way to achieve dimming control with an enhanced CRI, effectively improving lighting quality and applicability.