A Transfer Function Approach to Calculate the Radiation of a three-phase Inverter

The outcome of a radiation measurement is calculated using a transfer function approach. The setup is decomposed into the device under test and the remaining parts of the setup. The device under test is characterized as a Norton equivalent source and the setup is described by scattering parameters relating the connecting ports of the device under test to the antenna. The method is applied to a three-phase inverter and its limitations are discussed with this example.

I. Introduction

In our previous work [1]–[3], a transfer function approach has been introduced to calculate the outcome of radiation measurements which require a specific measurement setup in a semi or fully anechoic chamber. Since measurement time and chambers are expensive, it is shown how to replace radiation measurements by some conducted emission characterization of the device under test (DUT), if the transfer function between the DUT and the antenna has been determined before for the required antenna position and orientation. Firstly, the DUT is characterized as a Norton equivalent source. Secondly, the antenna voltage is calculated by the multiport theory. Finally, the settings of a spectrum analyzer are considered to ensure the comparability with a real radiation measurement. This procedure is used repeatedly when multiple antenna positions and orientations are required. There are two preconditions: 1)

the DUT has a linear terminal behavior,

2)

the DUT does not radiate itself. The radiation is mainly generated by the currents on the supply lines.