This paper proposes a fast method of 3D power synthesis for antenna arrays of arbitrary geometry, which allows to synthesize a desired radiation pattern while reducing the Dynamic Range Ratio (DRR) of the array excitations. The method adopts an auxiliary phase pattern in order to reduce the power synthesis problem to a field synthesis one. A cost function involving the desired far-field pattern and the amplitudes of the array excitations is iteratively minimized by modifying the auxiliary phase pattern and the array excitations. Numerical results show that the method allows to satisfy stringent pattern requirements with acceptable CPU times, while enabling the DRR control.