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978-3-8439-1005-7, Reihe Elektrotechnik
Umrichtersystem zur Nachbildung elektronischer Lasten mit oberschwingungskompensierter Energierückführung über das Versorgungsnetz
148 Seiten, Dissertation Universität Erlangen-Nürnberg (2013), Softcover, A5
This thesis describes a load emulation system for high power loads. The load emulation system is used to test power converters with real voltages and currents. Using a load emulation system improves the developing process for different power converters.
The requirements of a load emulation system are defined. In the emulation of power loads a high dynamic of the emulation converter is required. This dynamic response can be achieved with a high switching frequency of the converter. Therefore, different topologies of the emulation converter are presented. Multilevel and parallel half bridge concepts are compared with each other. For the emulation converter in the following thesis parallel half bridges with an interleaved switching concept are chosen. The transfer functions and controllers are calculated using the state space averaging technique for a dynamic number of parallel half bridges. By using this technique the transfer function and the voltage controller can be calculated for a varying number of parallel half bridges.
In high power emulations the energy consumed by the load emulation system needs to be fed back into the power grid. The consumed power is returned to the power grid using the energy feedback converter of the load emulation system. For this function the fundamental current controller of the energy feedback converter is calculated. During the load emulation several harmonics can be produced by the grid side converter of the device under test. These harmonics need to be compensated by the energy feedback converter of the emulation system. Therefore, three different harmonic current controllers are presented and compared with each other. The different harmonic controllers are compared on an 160kVA electrostatic precipitator power supply test system. In this case an electrostatic precipitator is emulated using the emulation system. The harmonics produced by the grid side converter of the device under test are cancelled by the harmonic controllers and the measured results are compared to each other.
Measurements are presented for the load emulation of an electrostatic precipitators power supply. The emulated load currents and voltages are measured for different operating points.