Carrier shifting algorithms for the mitigation of circulating current in diode clamped MLI fed induction motor drive

Abstract: Reduction of circulating current is one of the major considerations in inverter fed electrical drives. Diode clamped MLI enables higher output current per phase, thereby rating of the drive gets increased effectively. Various methods of triggering in the inverter legs creates better voltage profile and leads to the enabling of circulating current in the drive system. The induced circulating current flows through the apparatus neutral (N) and supply ground (G) is caused by the existence of parasitic capacitance. This circulating current may cause potential danger especially when parasitic capacitance poses large. In the past, different modulation techniques and conversion topologies have been introduced to minimize the flow of circulating current. However, these techniques lead to complexity, high cost, low voltage profile and efficiency due to lower modulation parameters. This paper proposes PS, POD, PD carrier shifting PWM algorithms for diode clamped MLI to tumbling the circulating current within the each phase of inverter legs. The performances of proposed algorithm, in terms of circulating current, THD, losses and efficiencies are analyzed theoreticallyand are validated via simulation and experimental results

Modelling And Simulation Of Lossless Damping Reduction By Vector Controlled Ac Motor Drive With An Efficient Lc Filter

In this paper Active damping technique isused to damp out the unwanted resonant frequencyoscillations and proposed for lossless damping of vectorcontrolledac drives with an efficient LC-Filter.  Thispaper mainly concentrated on protection of Inductionmotor and Synchronous motor under any balanced orunbalanced load conditions and this proposed techniqueis simulated with the combination of Voltage SourceInverter (VSI), LC Filter and AC Drives. However, theLC-Filter created unwanted oscillations due to internalresistance at system resonant frequency. This resistancedrop is emulated by controlling terminal voltage. Theproposed technique neither affects the dynamicresponse of the drive nor changes the design of thestandard vector control loops. This proposed techniqueis carried out in three phase domain for better accuracyof control. This paper has been implemented andsimulated by using MATLAB/ SIMULINK 7.8 (R2009a)version

Overvoltage at motor terminals in SiC-based PWM drives

Key points in the development of More Electrical Aircraft (MEA) are currently DC power distribution in higher voltage levels (540 V) and the use of disruptive technology such as Wide BandGap (WBG) semiconductors in power inverters. Using WBG components (SiC and GaN) increases the power converter mass density. However, fast switching of WBG components (tens of kV/s) induces voltage transient overshoots due to parasitic elements within the inverter. In addition, propagation and reflection phenomena along the harness connected to this inverter, even for small lengths, cause a significant voltage overshoot across the loads. Such overvoltage in Adjustable Speed Drives (ASD: association of inverter, harness and motor) supplied by the new HVDC 540 V aeronautical network could be fatal for the Electrical Insulation System (EIS). This paper proposes a fast and accurate modeling methodology to predict transient overvoltage; it allows us to analyze the impact of SiC inverter technology on overvoltage at motor terminals