# This result shows that for the

One can check that CGP 35348 when Rs = 0 Ω, λ?=0, and if f also equals zero, then Ωm is deduced from the location of the maximum of Cp(RΩm/Vw). This analysis allows one to define the optimal generator power coefficient asequation(19)Cogp(Ωm,Vw)=PgPw=Cp(RΩmVw)−Rsiq2+fΩm2Pw,where iq is given by Eq. (16). This coefficient evaluates the efficiency of the association of a wind turbine with a PMSG optimally controlled by the field oriented vector control principle, and the importance of the Joule and friction losses compared to the wind power. Fig. 3 shows a comparison of Cp and Cogp in our case. One important point to underline is clavicle since Rs and f are not zero, these two curves do not reach their maximum at the same abscissa. This means that when the value of the tip speed ratio λ for which Cp is at its maximum is used to compute the speed reference of a speed controlled generator, the highest power at the output of the generator is not provided. This justifies to directly maximize the power supplied to the load.