Sizing Optimization of the Synchronous Generator and the Measurement Uncertainty Analysis

Abstract

This study discusses the design process of a generator to utilize waste diesel engines in the automotive industry, and presents the results of the design, analysis, and test evaluation of a 78 kW permanent magnet synchronous generator. In the initial design process using finite element analysis (FEA) and space harmonic analysis, the number of poles and slots were determined. Then, the generator characteristics were investigated by the torque per rotor unit volume (TRV) method and the d,q-axis equivalent circuit. Lastly, the optimal size of the generator was determined. This process makes it possible to design in consideration of efficiency, inductance, material cost, and temperature characteristics. A prototype of the model was created and tested with uncertainty analysis, and a comparison between the experimental results and the results of the optimization was conducted to validate the analytic approach.

Existing System

Optimum rotor / stator diameter ratio of permanent magnet machines.

Proposed System

This paper deals with the design procedure of permanent magnet synchronous generators, especially focusing on how to determine the stator diameter, rotor diameter, and stack length during the design process. In the general design method, TRV (Torque per Rotor Unit Volume), current density, and SR (Shape Ratio) are the main factors that determine the size, stator diameter, rotor diameter and stack length of a permanent magnet synchronous generator. SR is the ratio of the stack length to the rotor diameter. The TRV and the current density are approximatively determined by the information of the field in which the generator is used and the cooling method, and the final value is determined after confirming whether the generator required performance is satisfied through the detailed design. SR is often determined by experience and the field to which the generator applies. The problem with the general design method is that if the generator has a problem with the heat after the detailed design, or if the required performance is not satisfied, it has to be redesigned after changing TRV, current density, and SR. In addition, even if thermal problems do not occur and the required performance is satisfied after design, it cannot be said that it is designed with the optimal value of TRV, current density and SR for improving the performance. In order to solve this problem, we improved the design procedure using the characteristic parameters of initial design model, TRV, SR, and TD (Torque Density).

Architecture

Block diagram of generating system