Fritze, Eric

A dynamical impedance analysis of complex electrical aerospace systems during operation can provide detailed information for efforts to further enhance system stability and reliability. As conventional single-tone impedance measurements are relatively slow compared to possible system state changes, a pulsed method using a synthesised stochastic multitone signal is proposed. This method is validated for a passive permanent magnet synchronous motor through a result comparison with an RF I-V impedance measurement. Then it is applied to an active DC- DC converter to highlight the detection of impedance changes due to the switching of the involved transistors, impossible to detect with conventional impedance measurement methods. It will be discussed how this method can be further adapted to overcome currently existing practical limitations and how it can be optimised for other electrical systems of interest.

In this paper the investigation of a modified version of the non-isolated cascaded buck-boost converter is presented in order to achieve a better voltage balancing of the converter with respect to ground. This should reduce common mode noise due to the parasitic capacitive coupling between the switching nodes, heat sinks and protective earth. Measurements confirm the balancing capabilities of the described symmetry circuit, leading to significantly reduced common mode noise.

This paper proposes a simple but robust control method for the effective operation of the cascaded buck-boost converter using only one output voltage controller in combination with logic circuits. The converter has an input voltage range from 450V to 750V, providing an output voltage of 600V and up to 15ARMS output current. An analytical single-controller design approach shows stable and robust behavior throughout the whole input voltage range in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM).

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.