**6. Summary and future developments**

Power electronics are developing rapidly and their cost is falling. These trends will continue to be used to reduce the cost of small wind turbines and improve their cost effectiveness. After briefly noting these trends, this Chapter concentrated on a modern converter topology suitable for grid connected small wind turbines: the backward very sparse matrix converter (VSMC). It has the potential to improve conversion efficiency by reducing switching losses. In turn, the ability to switch rapidly in a complex fashion has been made possible by recent improvements in digital signal processing technology. Like many modern topologies, the VSMC allows bi-directional power flow which can be exploited to motor start a small wind turbine and increase the energy extracted, at least for the artificial case of a step increase in the wind speed from zero. The strategy also lowers the cut-in wind speed and shows the importance of considering the whole turbine system when designing the converter.

Motor starting as the wind speed increased was analyzed to compare with conventional aer‐ odynamic starting assessed experimentally for a 5.0 kW wind turbine whose blades were designed to start quickly. Using the scaling outside the integral in Equation (5), the aerody‐ namic starting at any wind speed was determined. The simple analysis of Section 4 and the detailed Simulink modeling both show that an energy gain occurs for all wind speeds with motor starting. Moreover, the turbine can contribute energy to the grid at wind speeds be‐ low the conventional cut-in speed if motoring is employed. This strongly suggests that mo‐ tor-starting should be investigated for more typical wind speed variations. The results suggest a good practical strategy is to motor the turbine to 60% of rated rotor speed when the average wind speed is in the range of 4 to 7 m/s [26].
