Otimização do rendimento de um acionamento vetorial do motor síncrono de imã permanente

Abstract

This work is based on a motor used in the propulsion system for a small sailing boat. Efficiency in an electrical propulsion system is of considerable importance since the amount of available energy is limited by battery space and weight. Since the boat is using most of the time the motor in steady state condition at a load of 0.3 to 0.6 of the nominal power, the efficiency in this region will contribute most to the maximum travel distance on one battery charge. The motor is a Permanent Magnetic Synchronous Machine or in short PMSM and has a reasonable efficiency. Due to efficiency and other benefits, this motor is widely used in electric vehicles giving a contributing to the future of sustainable technology. A typical specification due to the abnormal rotor construction gives possibilities to improve the efficiency slightly by means of the motor controller. Even though the increase in efficiency is small, the implementation in the controller is without the need of additional hardware or sophisticated algorithms. Normally the motor controller is based on the maximum Torque per ampere condition, it is been concluded in this work that for this specific motor a slightly variation to this condition improves the overall efficiency. For the normal condition the magnetizing current Id is kept at 0A while in the essence of this work it is shown that an improvement of efficiency can be achieved when this current is altered or Id 6= 0. To put the motor efficiency in perspective the complete propulsion system is described in this thesis. The model of an idealized motor and the used controller is adopted from well known literature and used for simulation. More detailed analysis of the losses that take place in the motor extend the model making the simulation able to predict the efficiency while adapting the controller. For the steady state operating condition the efficiency is observed while varying the controller parameters, the simulation results show that the optimal efficiency for this motor is depending on the controller settings and can be optimized for certain conditions. After simulating for several conditions a series of measurements is done to validate the theoretical work. It is shown that in essence the optimal efficiency can be achieved for the controller settings as found during simulation. For the typical application the method proposed in this work is easy to implement, a calculated feed forward to the current Id based on the throttle command value will be sufficient to optimize the efficiency with a few percent. During the measurements it is been shown that a second variable can be used to even further optimize the efficiency of the system, this method is not estimated or simulated since it is outside the scope of the work. This variable sets the DC voltage of the bridge and for steady state it does not affect the control of the motor. With the conclusions and the proposed method this work is intend to give a contribution for usability for this kind of motor in electrical propulsion of boats.