Online fine tuning of current PI controllers in spin-dry cycle of washing machines

A washing machine is a good example of a complex system. To meet market standards of the white goods industry the main driving motor of a washing machine must be chosen correctly and controlled effectively. High performance permanent magnet synchronous motors (PMSM) are now becoming the dominant electrical motor used in washing machines. In order to reach the desired efficiency level with PMSM type motors vector control scheme should be applied while cost and reliability requires no sensor to be used. This paper proposes an online method for tuning the proportional and integral terms of current controllers, which control the direct and quadrature axis currents in vector control of PMSM. The tuning is based on Nelder-Mead optimization algorithm and experimental results for spin-dry cycle are presented.