To showcase its design capabilities, Gipfel EDS Ltd developed PowerPak, which is a pocket-sized lithium battery based 100W mains inverter and USB charger. The purpose of this exercise is to demonstrate to potential clients what Gipfel EDS Ltd can do in terms of product development in a short time-scale. This product was developed in just a few months.
The PowerPak has a 1A USB charging socket and a 100W 230V 50Hz mains output for portable power supply – such as camping, travelling, etc, when there is no available mains power. The power is sourced from an internal lithium battery pack which has temperature control, over-current, short-circuit and over/under voltage protection to ensure product safety. The battery is charged from an external supply and the PowerPak has integrated battery charging management – ie, constant current/ constant voltage charging.
The inverter generates a modifed sine-wave of which its average output voltage is regulated using a control loop to compensate for varying load conditions. The mains output has short-circuit and overload protection which is achieved by use of a sense resistor in the low side of the H-Bridge. The inverter is based around a push-pull inverter and a H-bridge output stage. The inverter achieved an efficiency of 91%.
Running in Inverter Mode
Running in USB charging mode
The design was carried out using Cadence OrCAD and the PCB is double-sided.
PCB assembly build
Internal lithium battery pack with protection thermistor
PCB assembly fitting into enclosure