Voltage sag mitigation technique for an electric vehicle

A voltage sag mitigation technique is presented that effectively mitigates both temporary voltage sags and prolonged undervoltage conditions for a large electric vehicle. A reserve voltage source with a dc-dc buck converter interface is switched into a series configuration with the main voltage source when a low-voltage condition is detected. The load voltage is then held constant through control of the buck converter duty cycle in response to load variation. Simulation and scaled lab model results show that this technique is an effective method of maintaining a specified voltage level during increased load demand.