An approach for thermal control of an electric heating system having halogen lamp heaters driven by AC line voltage with zero-cross switch is proposed. The feeding power is governed with a delta-sigma modulator estimating the resistance of the halogen lamps dynamically to evaluate the instantaneous feeding power. The thermal model of the halogen heater is identified with the linear functional model around an equilibrium point. The effectiveness of the proposed approach is demonstrated comparing the spectra of feeding power.