This paper proposes an adaptive voltage DC power supply design to overcome the voltage sag problem that occurs when starting an induction motor. When an induction motor is started, the inrush current drawn by the motor causes a decrease in the voltage across the grid-connected to this motor. This voltage sag can be compensated by injecting voltage into the grid. Because the voltage drop fluctuates, the injection voltage also needs to be adj usted in magnitude. Instead of using duty cycle control to obtain the appropriate voltage magnitude required, this paper proposes to use a variable resistor (VR) combination to control the output voltage of a boost converter. In this preliminary study, the voltage drop is divided into four regions, with different compensation voltage magnitudes for each region. The magnitude of the injected voltage during the voltage sag will be adjusted according to the magnitude of the voltage drop that occurs. The results of this study indicate that the voltage magnitude required to be injected into the grid can be met appropriately. The selection of the VR resistance value according to the magnitude of the voltage drop provides the appropriate inj ection voltage value as well. Further research is needed to increase the voltage area to be inj ected by the voltage from this power supply so that the voltage difference between the grid and the power supply can be reduced and produce a smaller voltage ripple.