Performance of a Boost Multi Level Inverter for Mining Applications

Abstract

In recent, much advancement has been witnessed in the field of drive systems. Electrical variable speed drives (VSDs) are integral to mineral processing and mining. VSDs are widely used in mining, drilling, traction, air compressors, water pumps, and conveyors. In fact, drives are back bone for any application, In the field of mining, drilling, traction systems drives are the only important parts of the entire control units. In this regard, the inner structure of drive i.e., inverter is key unit for the same. In the present study a novel inverter structure is designed for different mining, traction and conveyor applications. Although applications are plenty but still the proposed inverter is capable to meet the aforesaid applications. The back ground of drives system is that, for many years DC motors were used in mining applications. Steadily those motors are being replaced with AC motors due to several advancements in the AC drive technology. In addition to better control, AC motors require less maintenance than DC motors. Thus, controlling AC motors with drive system is a challenging issue. This aspect is key for new research and developments in the field of drives. Although voltage control and current control drives exists, still VSD’s have their own functions and features in terms of utilization. Traditionally VSDs are the part of the drive systems, VSD’s are mainly based on the conventional voltage source inverters (VSIs). Nevertheless, the conventional VSIs suffer from the barriers like output voltage limitations, harmonics, and control complexities. Since the loads are variable in the mining applications, continuous and reliable power converters are much needed. Multilevel inverters (MLIs) have become a promising alternative to conventional VSIs due to efficiency, ample power capacity, high-quality injected currents, and less complexity. Most of the available MLIs possess unity or stepped-down voltage feature. In such cases, a front-end boosting stage or step-up transformer at the output is used to meet the voltage requirement. Using MLIs with inherent boosting ability in such a scenario is more logical. Capacitor-based MLIs with boosting ability and self-voltage balancing are termed switched capacitor MLIs (SC-MLIs). Likewise, MLI topologies presented in this thesis amplify the voltage level using a single dc source. These units can be cascaded to produce higher levels by considering a proper choice of the magnitude of the multiple dc sources. The motivation of this research work is to emanate a novel switched-capacitor-based boost MLI for mining and drilling applications. In particular, the proposed inverter is designed for v nine-levels by using two capacitors as virtual sources. To support the proposed configurations, detailed operating principles, modulation, and real time results are presented. The Proposed MLIs is capable to generate large number of levels with a single source if it extended further. However, to achieve nine levels only 11 switches and 2 capacitors are used and this enables the proposed topology in compact and efficient manner.