چكيده به لاتين
In different applications, such as pump, compressor, ventilation, conveyor systems, fans and propellers, there is a high potential for improvement of efficiency due to variation of output torque and speed. According to great deal of power consumption by these applications, improvement of efficiency even by a few percent has a great impact on total energy consumption.
A review on previous researches shows that the main problems of maximum efficiency control methods of permanent magnet synchronous motors are difficulty of loss minimization condition and also difficulty in its implementation. Therefore in this thesis, in order to resolve these problems, an approximate model of permanent magnet synchronous motors is utilized to simplify the loss minimization condition; and a controller is used to directly solve the loss minimization condition. Afterwards, impact of parameter variation on four different control methods of permanent magnet synchronous motors and also the effect of utilizing parameter compensator in these situations are investigated. Then, a method is proposed in order to compensation of parameter variation with the aim of improving the response time of method. In the proposed method in order to improvement of response time to reach optimum point, initial guess of the operating point would be obtained from model-based method; then based on perturb and observe method, final optimum operating point will be obtained. Both of hybrid compensation method and search-based method are implemented experimentally and compared with each other.
According to importance of loss reduction in constant power region, utilizing inherent field-weakening of loss minimization methods leads to increment of maximum attainable speed on constant power curve. Via three different approaches of calculation, simulation and experiments, effect of voltage limitation on maximum attainable speed on constant power curve is investigated.
Multiphase multimotor drive systems need to utilize loss minimization methods due to increment of copper loss and reduction of efficiency in these systems. Therefore, maximum efficiency control method is modified for utilizing in these systems. In the proposed method, typically in a two-motor system, extra copper loss of the first motor, caused by reference currents of second motor, is considered in loss-minimization equations of second motor; therefore the total controllable loss of whole system will be minimized in a unified form.
