Design and Modulation of High Current Low Voltage Two-Level Multiphase Inverter
 Ippisch, Matthias  (08.04.2022)

Verlag: Shaker

Author: Ippisch, Matthias

ISBN: 978-3-8440-8525-9

Erscheinungsdatum: 08.04.2022

Größe: 148 x 210 (B/H)

Gewicht: 285

Bindung: Klebebindung

Reihe: Forschungsberichte Elektrische Antriebstechnik und Aktorik (48)

Sprache: englisch

Auflage: 1

Umfang: 190 Seiten

MwSt: 7 %

Due to the rapidly increasing use of electric motors in transportation and therefore safety-critical applications, inherently fault-tolerant multiphase machines are a topic of research with increasing interest. Besides the possibility of post-fault operation, multiphase machines are also capable of having lower torque ripple and higher power density than their three-phase counterparts. In order to make full use of the increased number of degrees of freedom in machines with a phase number greater than three, the modulation of the inverter has to be fully understood. This research tries to aid in reaching this goal. Thereby a focus is laid on but not limited to multiphase inverters with a low dc link voltage and MOSFETs as semiconductor switches. This thesis contains of four main parts. In the first part an in-depth investigation of the half-bridge switching behavior of low voltage MOSFETs for clamped inductive switching with synchronous rectification is performed, as the half-bridge is the smallest building block for multiphase inverters. Thereby sophisticated analytical modeling is compared to numerical simulation and measurements. Due to the high currents for high output power special attention is thereby laid on the parasitic inductances present in the switching circuit. The second part describes the theoretical framework for multiphase modulation, thereby enabling a general approach for arbitrary phase numbers and easy implementation. Modulation functions for the most popular space vector modulation schemes for single frequency output are derived in dependency of the phase number. Analytic formulas for the generated voltage harmonics are then derived, extending previous calculations performed for three-phase inverters to a more general form. Moreover, different modulation schemes for the overmodulation region are discussed. The third part is then dedicated to a comparison between the modulation schemes, addressing the most important figure of merit for feeding multiphase motor loads by a voltage source inverter. These include the active and passive component stress in the inverter, as well as harmonic current content adversely affecting the motor performance. Furthermore, optimal operation points for different modulation schemes are calculated and possible loss savings quantified. Finally, theoretical findings are put into practice by building up a 48V five-phase inverter. Measured results are compared to numerical simulation and the analytical calculations of previous chapters thereby verifying the approach.