Efficiency evaluation of linear permanent magnet synchronous machines using the synthetic loading method

In this paper, the concept of efficiency evaluation of linear permanent magnet synchronous motors using the synthetic loading method is described and evaluated. Synthetic loading is a method of efficiency evaluation that eliminates the need for a mechanical load to absorb generated shaft power. A mathematical model for synthetic loading is derived for the linear machine using the d-q machine model that includes core loss. The implication of synthetic loading frequency on the required inverter DC link voltage and inverter volt-ampere rating is discussed. In addition, the effect of additional mover mass on the synthetic loading frequency is described in order to get constant swing velocity. Synthetic loading and standard efficiency tests, as methods of efficiency evaluation, are simulated using MATLAB and SIMULINK. Simulation data is verified through the experiment for synthetic loading and the standard efficiency tests. Simulation and experimental results show that the synthetic loading method is capable of evaluating the efficiency of linear permanent magnet synchronous motor under test.