Modelling and optimisation of multi-airgap radial flux permanent magnet machines with PCB windings

Recently, several researches have been carried out on electrical motors with multiple air gaps. Until now, the flex-PCB windings designed by Mirmex have never been used in radial flux permanent magnet (RFPM) brushless DC (BLDC) motors with multiple air gaps. The flex-PCB windings developed by Mirmex Micro Motors could offer interesting possibilities for those motors. This Master’s thesis explores the possible advantages of the RFPM multiple air gaps BLDC motors with FPCB windings compared to classical single air gap ones. As a first step, the motors have been simulated thanks to analytical models. Thereafter, a genetic algorithm has been used to optimise single and multiple air gaps motor based on the developed models. Thanks to those optimisation results, the efficiency of the single and double air gaps motors has been compared for different motors' size and nominal operating conditions. First observations show that double air gaps motors seem to be more efficient in low torque and high speed applications. In addition to that, it has been shown that the efficiency of double air gaps motors can be higher than the single air gap motors one for very specific external dimensions.