Power Transmission and Control in Microturbines’ Electronics: A Review

When the shaft rotates in microturbines, the rotational movement is converted to electrical power. This is achieved through a permanent magnet synchronous machine (PMSM) housed on the shaft and the power electronics components. To the best of the authors’ knowledge, articles that comprehensively describe the power transmission and control in the electrical part of microturbines have yet to be introduced, namely, the PMSM and power electronics. This review paper presents a detailed review of power conversion in each component of the electrical part of microturbines. The paper also reviews the existing literature on microturbines’ electrical performance, noting areas where progress has already been made as well as those where more research is still needed. Furthermore, the paper explains the control system in the electrical part of microturbines, outlining the grid synchronisation control approach for grid-connected microturbines and reviews the possibility of employing control strategies that engage the PMSM and power electronics as controllers for certain variables in microturbines, such as the shaft rotational speed and torque. Such control methods are more crucial in externally fired microturbines since traditional control strategies used in internally fired microturbines, such as thermal input regulation, are no longer an option in externally fired microturbines for controlling the shaft speed. The significance of higher switching frequencies in power electronics is also discussed. The higher switching frequency, the faster response to load variations and, therefore, the more reliable the control system. A greater switching frequency allows for reduced power loss, cost, and unit size. In this context, it is recommended in this review paper that future research consider using silicon carbide switching devices rather than silicon ones, which is the current practice, to build up the microturbines converters’ topology. The recommendation was motivated by looking at the existing literature that compares the switching frequency, size, cost, thermal endurance, and power losses of silicon and silicon carbide components in applications other than microturbines since initiatives of using silicon carbide in microturbine power electronics have not been reported in the literature, as far as the authors are aware. The electrical components of microturbines account for a third of the entire size and cost of the unit. This means that reducing the size and cost of the electronics contributes effectively to reducing the total size and cost. In applications other than microturbines, silicon carbide exhibited promising results compared to silicon in terms of size and long-term cost. Investigating silicon carbide in microturbines is worthwhile to see if it provides such promising benefits to the microturbine unit.