Design and implementation of a robot power supply system

Mobile robots often rely on a battery system as their main source of power. These systems typically produce a single voltage level, yet the robot subsystems may require a variety of voltage levels. Thus, a robot power supply must be designed to provide the subsystems with all of the necessary voltage and power demands. Student design work has progressed on a multifunctional robot project at Elizabethtown College. Current work has been focused on the design and fabrication of the robot power supply system. Since the main power source for the robot is a DC battery system, the power supply will consist of a combination of switched mode DC power converters. Choosing from the wide variety of existing DC converter topologies requires proper design consideration for the system voltage levels, component voltage ripple requirements, and overall converter efficiency. The main DC battery system also powers the drive motors, thus, voltage isolation and filtering is desirable for the robot's computer subsystems. A flyback converter topology is utilized to supply voltage isolation and regulation while subsequent buck converters are used to meet the remaining voltage requirements. This paper provides design and fabrication details on the buck converters used in the power supply system. The design meets the present robot subsystem requirements and allows for future project expansion, while the converter's efficiency maximizes the overall operating time for the robot. Experimental results show the converter efficiency and voltage ripple at rated load. A discussion of lessons learned provides insight into the need for proper component selection and placement, printed circuit board fabrication, and ensuring a proper ground plane for successful implementation of a switched mode DC power converter.