Low frequency modulation techniques for transistor-clamped h-bridge based cascaded multilevel inverter

Wahidah, Abd Halim (2015) Low frequency modulation techniques for transistor-clamped h-bridge based cascaded multilevel inverter. PhD thesis, UM.

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This thesis is concerned with the transistor-clamped H-bridge (TCHB) based cascaded multilevel inverter to produce an AC output voltage with low total harmonic distortion (THD). It is one of several distinct static power converter circuits that can produce three and more voltage levels. For example, when the adopted inverter is designed with three TCHB cells, a thirteen levels of output voltage is produced. This work also contributes to several of the issues regarding the multilevel inverter, mainly with low-switching frequency modulation. Two modulation methods for obtaining the optimum switching angles have been proposed. The first method is a selective harmonic elimination (SHE) modulation by means of an offline angle calculation using the Newton-Raphson method. The second method is closed-loop control also for low-switching frequency modulation using proportional-integral (PI) controller through online angle determination. The analytical results are validated using both simulation and experimental results. Simulations of the adopted inverter with a wide range of modulation indices for various load arrangements and reference frequencies are presented. The experimental and real implementation of SHE modulation and closed-loop operation for the adopted inverter using an Altera field-programmable gate array (FPGA) are presented. An in-depth investigation of the modulation strategies and hardware implementation issues has been carried out. Results show that the adopted inverter operates correctly under all forms of modulation strategies. The relative merits of the SHE modulator and closed-loop control operation are assessed based on output quality. Investigations of SHE modulation have revealed that the switching pattern can reduce the harmonics contents of the staircase output voltage. Meanwhile, the successful closed-loop control of the adopted inverter was capable of producing output voltage with minimal THD.

Item Type: Thesis (PhD)
Uncontrolled Keywords: pulse-duration modulation, pulse modulation (electronics)
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: Library > Tesis > FTK
Depositing User: Noor Rahman Jamiah Jalil
Date Deposited: 19 Nov 2015 00:41
Last Modified: 19 Nov 2015 00:41
URI: http://eprints.utem.edu.my/id/eprint/15287
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