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This paper deals with the resistive losses in the deep-bar induction motor fed by a PWM inverter. The effect of harmonics from the inverter on the resistive losses of the induction motor is investigated by varying the amplitude or phase of the harmonics. The investigation is performed on 45 kW and 1250 kW induction motors. The equivalent circuit of the deep-bar induction motor is presented and used...
This study deals the problem of DC-link capacitor voltages balance in five-level inverter. The proposed solution is based on the redundant switching vectors using the selective harmonics elimination SHEPWM instead of space vector modulation [3]. The inverter supplies a high power induction motor of 20MW. The obtained results prove that the balancing of the dc capacitor is kept with canceling the most...
Our purpose is to reduce the power loss in three-phase voltage-source inverters. We describe a switching algorithm that uses the conventional PWM method in the low modulation range and alternative discontinuous PWM (ADPWM) in the high modulation range to reduce the switching loss in three-phase inverters. The algorithm reduces the switching loss to 40% that of the conventional PWM method. The experimental...
A 12-pulse phase-controlled rectifier has been used for high power applications. It consists of two sets of 6-pulse rectifiers. Basically they operate in parallel, but they operate alternately if load is light. The commutation of the DC current between the two rectifiers is examined and it is found that harmonic distortion of the input current is automatically minimized if they operate in the boundary...
Multilevel inverters with a large number of steps can generate high quality voltage waveforms, good enough to be considered as suitable voltage source generators. A modified Sinusoidal Pulse Width Modulation (SPWM) modulator with phase disposition that increases output waveform up to 7-level while reducing output harmonics is presented in this paper. The proposed modulation technique can easily be...
This paper presents the use of dithered sigma-delta modulation (ΣΔM) to mitigate low and high frequency harmonics of pulse-width modulated (PWM) inverters without increasing switching losses. A PWM bit stream generated by a 1 bit- 1st-order discrete ΣΔM is converted into a continuous pulse train which controls the inverter operation. The minimum pulse width of the pulse train is strictly defined by...
The text aims at the harmonic pollution and powerless of the electronic network caused by inverter. Based on the foundation of power device IEGT and dual-PWM three-level inverter characteristics, the contrast of the rectifier three-pulse PWM modulate mode and the triangle PWM modulate mode is given. As a result, IEGT dual-PWM three-level inverter possesses the characteristics such as the good input...
This paper presents the simulation of a new topology for the power injection system of a single-phase grid connected photovoltaic generation system that is based on the parallel association of two voltage source inverters: one is a 3 level neutral point clamped operated using a low switching frequency strategy and the other is a 2 level inverter which operates with a pulse width modulation based strategy...
An improved pulse width modulation (PWM) method for three-phase inverters using the Walsh function harmonic elimination method with harmonic injection technique is presented, together with a noniterative algorithm that produces a set of linear equations that relates switching angles with the output phase voltage fundamental. The approach used gives a set of solutions with a near-linear trajectory...
The paper presents an overview of the pulse width modulation (PWM) techniques for a feed-forward voltage source inverter. Classical and optimized modulation methods are treated regarding the ease of implementation, harmonic spectra, maximum modulation index and switching losses. Classical PWM procedures like naturally sampled with saw-tooth or symmetrical triangle-carrier-wave, regular sampled and...
This paper presents the effect of dithering on both harmonics and interharmonics in adjustable speed drives (ASDs). Using a voltage source configuration, a six-pulse rectifier and a sinusoidal pulse width modulated (SPWM) inverter are modeled in the PSCAD/EMTDC simulation platform. The pulse width modulated (PWM) signal for the inverter is modified by means of the additive dither noise. The dither...
For improving the dynamic response of the system, most of the pwm voltage source inverters are operating with inner current control loop. The application includes high performance ac drives, active filters and power supplies etc. Recently pwm voltage source inverters are employed in grid connected distributed power generating systems in order to provide secure and reliable power to the utility grid...
A dc-bus capacitorless rectifier-inverter motor drive is discussed in this paper. Two three-phase, two-level voltage-source converters (VSCs) are connected back-to-back to form an AC-AC regenerative converter. Only the motoring operation of the regenerative converter is studied in this paper. The lack of a dc-bus capacitor results in low-frequency dc voltage ripple following the rectification of the...
The aim of this paper is to present a complete design procedure for a current source converter (CSC) that consists of a PWM current source rectifier (CSR) and inverter (CSI) feeding an induction motor. The procedure includes dimensioning of the input and output filters, as well as the dc-link choke. State-of-the-art SGCT devices are employed in the design and their losses and junction temperatures...
For three level Space Vector Pulse Width Modulation (SVPWM), it is important to make sure that the phase voltage will not change by two levels in one time. It is found out that some even order harmonic elimination PWM method may cause the phase voltage to jump by two steps when asymmetrical uniform sampling technique is used. The condition when two-level voltage jump happens is found out. A new three...
In this paper, the operation principle of the Z-source inverter is analyzed in detail. According to the characteristics of allowed short-shrougt zero state in the Z-source inverter, SPWM control method of the Z-source inverter is obtained by inserting fixed short-shrougt zero state into zero state of SPWM. It is simple and easily implemented in practice. However, in inductive load condition the output...
The main advantages of the high speed machine are small size and high power density. However, the high speed machine suffers from higher loss density and cooling difficulty due to small cooling area, especially the high frequency harmonic currents produced by the power conversion system increase the loss and temperature of high speed machine. The output high frequency AC power of the high speed PM...
The static synchronous compensator(STATCOM) using power electronics as a shunt device of the Flexible AC Transmission Systems (FACTS) is attracting an increasing interest in power system research and in electric utilities. This paper proposes a novel multi-level structure topology with zigzag transformer for three-level inverter used in STATCOM. Moreover, selective harmonic elimination pulsewidth...
This paper presents the synchronous harmonic optimum pulsewidth modulation (SHOPWM) for three level diode clamped inverter. First, the problem of minimizing stator current harmonics when the asynchronous machine is fed by PWM inverter is introduced. A distortion factor in proportion to the total stator current harmonic distortion is selected for solving the problem. A subsection synchronization modulation...
The main advantages of the high speed machine are small size and high power density. However, the high speed machine suffers from higher loss density and cooling difficulty due to small cooling area, especially the high frequency harmonic currents produced by the power conversion system increase the loss and temperature of high speed machine. The output high frequency AC power of the high speed PM...
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