A new pulse width modulation technique for neutral-point clamped voltage source inverters

Author(s):  
Jose A. Riveros ◽  
Juan Jose Galeano ◽  
Adolfo Meza ◽  
Marco Rivera
Author(s):  
Nhờ Văn NGUYỄN ◽  
HONG-PHONG NGUYEN LE

Multilevel voltage source inverters (VSIs) have been used for several decades thanks to their advantages compared with traditional two level VSI. Among various types of multilevel configuration, the T-type neutral-point-clamped VSI (3L TNPC VSI or 333-type VSI) has gained the attention in recent years. Due to the unique structure, the 333-type VSI has critical issues in reliability in operation such as switch-open-circuit (SOC) and switch-short-circuit (SSC), which lead to several unrequired issues, for instance, reduction of system performance, distorted and unbalanced output voltages and currents, or triggering the protection circuits. In some applications, the amplitude reduction and harmonics distortion of output voltages in SOC faults are not acceptable. Therefore, it is necessary to develop a pulse-width modulation (PWM) algorithm for 333-type VSI working under SOC fault which guarantees the desired output fundamental component voltage. The simultaneous SOC fault on two neutral-point-connected legs in the 333-type VSI may cause a large reduction in the output voltage. Under this circumstance, the 333-type VSI becomes an asymmetrical one called 322-type VSI. Certain studies regarding to the operation of 333-type VSI under SOC faults have been carried out. However, these studies require more semiconductor devices in order to create a redundant switching circuit. This leads to higher system cost with reduced inverter effieciency due to the additional loss. In this study, two carrier-based pulse-width modulation (CBPWM) techniques, i.e. 322-sinusoidal PWM (322-SPWM) and 322-medium offset CBPWM (322-MOCBPWM) are proposed for 322-type VSI. The proposed techniques are firstly simulated in MATLAB/Simulink and then implemented on a hardware setup. Performances of the proposed techniques are evaluated in terms of total harmonic distortion (THD) and weighted-THD (WTHD) of output voltages. Simulation results show that considering the worst output voltage under SOC fault, vBC, the proposed 322-SPWM technique could improve the THD by 40% and the WTHD by 94% compared with the uncompensated case with m=0.8. The corresponding results of 322-MOCBPWM technique are 42% and 96%, respectively. Characteristics of THD and WTHD values are also presented for demonstration the effectiveness of the proposed algorithm.


Author(s):  
Jyothi B ◽  
M.Venugopala Rao

<p>Multiphase (more than three phases) is very much popular due to their eminent features compared to conventional three-phase counter parts. In order to drive the multiphase machine, it requires same phase input w.r.t the no of phases at the output. This paper mainly focuses on five phase, because even after failure of one phase, the performance does not degraded much. Voltage source inverters (VSIs) are used to feed the induction motor. voltage source inverters (VSIs) switches are ON and OFF precisely to control the output. In order to implement harmonic waveform characteristic, carrier based PWM (pulse width modulation) is performed. By using with and without third harmonic injection machine torque is highly improved. Using MATLAB software, the simulation results are presented in the form of computer traces and high traded performance of the machine are discussed.</p>


Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4352 ◽  
Author(s):  
Riccardo Mandrioli ◽  
Aleksandr Viatkin ◽  
Manel Hammami ◽  
Mattia Ricco ◽  
Gabriele Grandi

A complete analysis of the ac output current ripple in four-leg voltage source inverters considering multiple modulation schemes is provided. In detail, current ripple envelopes and peak-to-peak profiles have been determined in the whole fundamental period and a comprehensive method providing the current ripple rms has been achieved, all of them as a function of the modulation index. These characteristics have been determined for both phase and neutral currents, considering the most popular common-mode injection schemes. Particular attention has been paid to the performance of discontinuous pulse width modulation (DPWM) methods, including DPWMMAX and DPWMMIN, and their four most popular combinations DPWM0, DPWM1, DPWM2, and DPWM3. Furthermore, a comparison with a few continuous techniques (sinusoidal, centered pulse width modulations, and third harmonic injection) has been provided as well. Moreover, the average switching frequency and switching losses are analyzed, determining which PWM technique ensures minimum output current ripple within the linear modulation range at different assumptions. Numerical simulations and laboratory tests have been conducted to extensively verify all the analytical claims for all the considered PWM injections.


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