Reduction of DC link capacitor stress for double three-phase drive unit through shifted control and phase displacement

Abstract

In automotive industry space is extremely limited. The efficient and fast control of electric motors is a key technology to save energy and space. This paper shows strategies to improve energy consumption of a redundant Voltage Source Inverter (VSI) and an associated double three-phase Permanent Magnet Synchronous Motor (PMSM). Focus is to significantly reduce the DC link power dissipation of the power electronics to extend life time or to reduce the capacity and thus the size required to install the capacitors. In particular, shifted control technique and in addition phase displacement are developed and implemented on a drive unit used in automotive application to control the multi-phase system. Analytical calculations show that these strategies reduce the DC link capacitor effective current value. The conventional three-phase PMSM is compared with the double three-phase PMSM run with the new control strategies.

Multi‐phase VSI DC‐link capacitor considerations

“…However, they do not then carry the analysis or investigation forward to quantify the potential reduction in VSI DC‐link capacitance and current rating. Although some investigations have been done on DC‐link capacitor reduction by increasing the machine drive system phase number from three‐ to nine‐phase [8], interleaving two sets of three‐phase VSIs [9] and phase shifting in a four‐phase DC−DC converter [10], a physical insight, comprehensive and quantitative DC‐link capacitance and root mean square (RMS) current rating investigation, and DC‐link capacitor design procedure for arbitrary phase number VSIs has remained unseen to date.…”

Reducing root‐mean‐square current stress on the DC link capacitor of a five‐phase electric drive through multiple carrier pulse‐width modulation technique

“…In the last few years, in the field of the multi‐3‐phase drives, the angle of phase shift between PWM carriers for the different n ‐phase inverters has been introduced as an additional degree of freedom [2, 15] in order to reduce the DC link RMS current. In [2, 16], the authors proposed a traction drive solution that uses a double‐three‐phase machine supplied by two converters in which the PWM carriers have been interleaved in order to reduce the DC link stress. A complete analysis of the technique has also been offered for three‐phase machine supplied by three inverters and for a triple‐3‐phase machine supplied by three inverters [15].…”