Common mode voltage elimination PWMs for a dual two-level VSI with single inverter switching

Abstract

This paper discusses two new pulse width modulation (PWM) switching methods for eliminating common mode voltage (CMV) in the dual two-level voltage source inverter (VSI). Both the PWM methods also ensures that the switching power loss is limited to one inverter only at all instants of time. Analytical expressions for switching times of the phase switching devices of the two inverters are developed to force the CMVs in a dual two level VSI configuration to zero which enables the dualinverter drive to be driven from a single DC power supply. The implementation of the proposed PWM algorithm depends only on the instantaneous magnitudes of the reference space vector on the stationary reference axes. The impementation totally avoids use of sector identification and also the use of look up tables.Index Terms-Dual-inverter, Three-level inverter, Open-end winding induction motor drive, Pulse width modulation, Common mode voltage.

The Effect of Common-Mode Voltage Elimination on the Iron Loss in Machine Core Laminations of Multilevel Drives

“…This voltage has a considerable third harmonic and its multiples [1], see later in section IV. In order to eliminate the CMV from a drive-system, it is essential to analyze the converter operating space vector and classify it into two groups, i.e.…”

“…Generally speaking, CMV is defined as the instantaneous voltage difference between the two grounds of two isolated power systems [1]. In the used converter circuits, the CMV of converter-1 (v CMV1 ), the CMV of converter-2 (v CMV2 ) and the CMV of the dual converter configuration can be expressed by (1)(2)(3).…”

“…This voltage has a dramatic effect on the machine bearings and insulations. Moreover, it causes an electromagnetic interference which has undesirable effects on the digital controller and the equipped sensing units [1]. A frequently used modulation technique to eliminate the CMV in multilevel converters is the space vector pulse width modulation (SVPWM).…”

“…A frequently used modulation technique to eliminate the CMV in multilevel converters is the space vector pulse width modulation (SVPWM). The CMV elimination (CMVE) using the SVPWM is based on modifying the switching scheme of the converter switches in order to deliver a zero third harmonic content, and its multiples, in the converter phase voltage [1]. The use of some space voltage vectors is omitted, in particular those that contribute to the generation of a third harmonic content in the converter phase voltage.…”

A Multilevel Converter With a Floating Bridge for Open-End Winding Motor Drive Applications

“…1. It is possible to use a single supply for the dual inverters with a common mode elimination technique [15,21,22]. These topologies use specific switching combinations that produce equal common mode voltages which cancel at load terminals.…”