[W-MO-85] Evaluating Efficiency Map considering the Effect of the Inverter

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Overview

1. Background
Along with high efficiency of electromagnetic equipment, highly accurate loss analysis is an important subject in electromagnetic field analysis. Permanent magnet synchronous motors and induction motors are often driven by inverters such as PWM system for variable speed operation. It is known that the inverter generates time harmonic components (hereinafter referred to as carrier harmonics) derived from carriers in the current of the motor and increases iron loss. It is important to consider this carrier harmonic in order to accurately calculate the efficiency of rotating machines performing the variable speed operation.
There are two approaches to draw the efficiency map. First is using the plant model generated from FEA models. In order to draw the efficiency map, it requires determining the current vector to achieve highest efficiency at the operating point. This searching requires parametric analysis changing the current vector. By using the plant model, the calculation time can be reduced significantly.
Second approach is using FEA directly to draw the efficiency map. This approach takes longer time than the first approach but it can capture the effect that the plant model doesn’t have such as the eddy current or the effect of time harmonics components.
In this paper, we propose a method that combines two approaches to calculate the efficiency at various operating points considering the influence of time harmonics and other effects in the shorter time.

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