The high switching frequency associated with pulse width modulation (PWM) that is commonly utilized in controlling the motion of high performance motor drive systems leads to motor iron losses. In addition to fundamental component, line voltages generated by voltage source inverters or other types of converters include harmonic components. Minimization of the harmonic losses leads to higher motor efficiency. Minimization of the harmonic losses can be accomplished in two stages: first at the design time and the second at the test time. In the first stage, the motor design can be optimized such that it can work in an efficient way for a given range of switching frequencies. In the second stage, the operation of the machine and inverter is optimized such that the total losses of the machine and inverter can be minimized. By measuring the motor harmonics loss for a given switching frequency, it is possible to find analytical model that is suitable for estimating the motor harmonics at all operating points. It is also possible to find the optimum switching frequency, modulation index, and power factor that minimize the motor- inverter total loss.Since it is difficult or inaccurate to estimate the harmonic losses of machine through analytical approach, most researchers resort to finite element analysis (FEA) instead of analytical solution. The limitation of using finite element software is that it is both time-consuming and difficult to be implemented in real-time control algorithms. For example, if it is required to optimize a design that is constructed and analyzed in FEA software, hours are typically needed to complete such a task. The proposed work in this thesis is a combination of analytical and numerical methods that are able to calculate the PMSM harmonic losses at any operating point with less execution time and adequate accuracy. Moreover, the motor fundamental losses and the voltage source inverter losses are also modeled such that the inverter-motor efficiency can be tested for different conditions. Numerical simulation of the field oriented control have been conducted and results include current, modulation index, power factor, switching frequency and all the variables in the drive system. Furthermore, Maximum efficiency control strategy has been chosen such that the drive system can work at the most efficient condition at all operation points. The proposed work is presented in the context of drive system that is based permanent magnet synchronous machine (PMSM). However, the proposed method can be extended to induction motor drive system or any motor use SPWM in controlling the inverter output voltage.
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