SBIR Phase I: Compact High efficiency Multilevel Motor Drive

The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase I project will be in enabling a new class of smaller, more efficient, and cheaper motor drives to be built. Since the motors use 43% - 46% of the world's electricity, any improvement in efficiency has the potential to have one of the greatest impacts on overall electrical energy efficiency due to the shear amount of power this application uses. Motors using this technology will be variable speed enabling energy saving opportunities in many applications. A decade ago, there was a push for integrated drive and motor products, but this failed, at least in all but the smallest motors. The primary reasons were the drive was more expensive and often larger than the motor itself in high power applications. This created a situation where it did not make technical or commercial sense to integrate the drive and the motor. Since that point the cost and size of the drives has reduced significantly, but the opportunity for widespread integration cannot be realized until significant additional size and cost reduction is achieved. This proposal will show a path that this integration works for many applications in the 40-1000kW size range. The intellectual merit of this project includes a new approach to multilevel motor drives. This multilevel technology has not found commercial applications in lower power, lower voltage (<1000V) applications, with traditional two level inverters dominating the market. This is driven by the abundance of established designs as well as the simplification and robustness of control. As control and semiconductor size and costs continue to reduce, the size and cost of these devices are dominated by filters and thermally driven packaging. With the advances in low size and cost digital control it now becomes possible to implement multilevel technologies at lower voltage and power levels. This implementation in a regenerative configuration will dramatically reduce the filter requirements as well as improve efficiency in both the drive and the motor. The efficiency improvement in conjunction with distributing the switch heat more widely will allow smaller more compact thermal solutions. Therefore, this approach will dramatically reduce the size and cost of the largest and most costly items at the expense of increasing the size and cost of the smallest and lowest cost items. This program will develop methodologies and designs that can achieve power densities that are 5-10 times higher than commercially available.