Optimized space vector modulation for DC-link balancing in three-level neutral-point-clamped inverters for electric drives

Battery Modeling and Parameter Extraction for Drive Cycle Loss Evaluation of a Modular Battery System for Vehicles Based on a Cascaded H-Bridge Multilevel Inverter

“…It should be noted, that the battery series inductance is neglected in (10) and (11) due to the commonly low pulse frequency and the direct connection of the battery cell tester. In an actual vehicle, the inductance is closely related to the cable and wire harness routing.…”

“…However, for a two-level setup, the inductance is estimated to be 1 μH for a 10 kWh, 400 V traction battery and about 500-700 nH for the 2m-long cable routing, seen from the inverter [18], [53], [54]. Nonetheless, the transfer function in (10) and (11) can easily be parameterized using a generic recursive least-square fit. Therefore, numerical computer tools, such as MATLAB's curve fitting toolbox, can be used.…”

Multibattery-Fed Neutral-Point-Clamped DC–AC Converter With SoC Balancing Control to Maximize Capacity Utilization

“…Very few works in the literature have focused in the study of multi-battery-fed NPC conversion systems [8]- [13], and almost all of them have only considered the three-level case [8]- [12], which is the most simple. In [8] and [9], a nearestthree-vector (NTV) space-vector-modulation (SVM) approach is used, and the batteries SoC are balanced through a suitable selection of small vectors.…”

“…Instead, [10] uses a combination of NTV SVM and radial state SVM, the latter replacing the use of medium vectors by the two nearest large vectors. In [11] and [12], a level-shifted carrier-based pulse width modulation (PWM) approach is used, and an offset is added to the modulating waveforms to control the power balance between the two energy storage units connected at the dc-link.…”

“…If basic conventional modulation techniques are used, based on the assumption that all battery voltages are equal, this will introduce low-frequency distortion in the converter ac terminal voltages. Although some advanced conventional modulation strategies have been proposed for the threelevel case to avoid introducing low-frequency distortion [8]- [9], [11]- [12], these modulation strategies feature a significantly increased computation complexity as a function of the measured battery voltages. In addition, the errors in the battery voltage measurements inevitably lead to low-frequency distortion.…”