This paper investigates the use of the Dual-slope Delta Modulation (DSDM) technique for the control of a dynamic voltage restorer (DVR) that can mitigate the voltage sag problems in power systems. Traditionally, the DVR uses the pulse-width- modulation (PWM) technique to control the power electronic switches in the voltage source inverter (VSI). However, VSI suffers from several disadvantages, such as ripples in the output voltage, high dv/dt and high total harmonic distortion (THD). To overcome these problems, this paper proposes the application of a dual-slope delta modulation (DSDM) technique for use in a DVR controlled by the current source inverter (CSI). The DSDM controller is tested to control the CSI in two configurations of DVRs to mitigate the voltage sag. The simulation results show that the proposed CSI-DSDM controller is effective to mitigate the voltage sags using both DVR schemes by accurately injecting the required missing voltage both in magnitude and phase angle.