Hybrid front end converters for large multi-motor applications integrated with energy storage

To supply the AC drive systems several Active Front Ends (AFE) with DC choppers are used to insure a reliable and acceptable harmonic current spectrum operation. Recently, energy storage system integration with the mining equipment has received industry attention, especially for peak load shaving and smarter energy management of the mine. Currently, the regenerative energy is often burnt into the choppers and is not fed back to the grid. The industry is motivated to capture this regenerative power since it can be as high as 60% of the motoring power and as high as 24 MW. Therefore, there is a possibility of large cost reduction and component downsizing. However, present status of development seems not to be very promising mainly because energy storage systems, (such as ultracapacitors) are still considered as an add-on part to existing products. In this paper, we investigate the operation of the current state-of-the-art front end converter systems for multi-motor applications. In particular, we propose power conversion configurations and methodology to determine the suitable energy storage technology for development of the multi-motor mobile mining equipment that has encouraging incentives for both the manufacturer and the mine operator.