Search

In this work, a multilevel 42-sided polygonal space vector structure for suppression of lower order harmonics for open-end induction motor (OEIM) drive applications is proposed. The proposed power circuit topology consists of two inverters feeding an OEIM from either side. The main inverter fed with a single dc-link providing active power for motoring operation is switched at low switching frequency. The secondary inverter fed with a capacitive supply is switched at high frequency to suppress lower order harmonics upto 39th order, up to the base speed of operation allowing maximum utilization of the dc-link. The advantages of lower order harmonic suppression in motor phase voltage, for polygonal space vector structures, are combined with multilevel inverter topology. This offers various advantages like multilevel operation with low inverter switching for the main power delivery inverter and harmonic suppression throughout the modulation range. The low switching frequency primary inverter generates harmonics of the order $6*k \pm 1$ , where $k = 1, 2, 3,{\ldots }$. The harmonics are suppressed by the capacitor-fed secondary inverter, which supplies only reactive power for suppression of lower order harmonics in motor phase voltage. Use of a single dc-link facilitates four-quadrant operation of the inverter. The proposed scheme is validated for steady-state and dynamic performance by experimental results. [ABSTRACT FROM AUTHOR]

This article proposes an inverter topology for the first time for suppression of all lower order harmonics (5th, 7th, 11th, 13th, etc.) up to 39th harmonic. The lower order harmonic suppression is achieved by switching the 42-sided polygonal vectors, which eliminates harmonics in phase voltage without using a passive LC filtering technique. The power circuit topology uses a single dc-link supply for the primary inverter. The secondary inverter is fed with a capacitive supply. A novel topology is proposed for the dense six-level secondary inverter. The lower order harmonics in phase voltage are suppressed using the secondary inverter, which acts like a switched-capacitive filter. This article also proposes a novel capacitor voltage-balancing scheme for the first time, which achieves voltage balancing for secondary inverter capacitors. The voltages of secondary inverter capacitors are balanced using the power balance relationship between the primary inverter and the motor load. An experimental study of the topology and the capacitor-balancing scheme is presented for the validation of proposed scheme. [ABSTRACT FROM AUTHOR]