Pulse Width Modulation for Power Converters : Principles and Practice

ISBN: 0471208140
Source: IEEE Xplore

ABSTRACT An integrated and comprehensive theory of PWM The selection of the best algorithm for optimum pulse width modulation is an important process that can result in improved converter efficiency, better load (motor) efficiency, and reduced electromagnetic interference. However, the identification of the best approach is a complex process requiring extensive mathematical manipulation. Pulse Width Modulation for Power Converters: Principles and Practice is the first single-volume resource written to help researchers in the field attain a working knowledge of the subject. The authors bring together today’s seemingly diverse approaches into a single integrated and comprehensive theory of modulation. The book provides a generalized approach to the fundamentals of PWM, looking at:
Active switch pulse width determination
Active switch pulse placement within a switching period
Active switch pulse sequence between phase legs and across switching periods
The main benefit of this generalized concept is that once the common threads are identified, the selection of a modulation strategy for any converter topology becomes immediately clear, leaving only secondary factors, such as practical performance, cost, and difficulty of implementation to consider. Additionally, it allows the performance of any particular converter topology and PWM strategy to be quickly and easily identified without complex and time-consuming analysis. Pulse Width Modulation for Power Converters: Principles and Practice enables the reader to achieve optimum PWM results for any application.

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    ABSTRACT: Five-phase variable-speed drives currently are considered for numerous applications, including electric and hybrid-electric vehicles, traction, and ship propulsion. If the machine is designed with a concentrated stator winding, the third stator current harmonic injection can be used to enhance the torque production and the machine needs to be supplied with the fundamental and the third harmonic of the voltage. On the other hand, if the machine is with a sinusoidally distributed winding, the supply should consist of the fundamental harmonic only. Since five-phase drives are invariably supplied from five-phase voltage source inverters (VSIs), adequate methods for VSI pulse width modulation (PWM) are required. This article analyzes different space vector PWM (SVPWM) schemes for a five-phase VSI, which can be used for five-phase motor drives with sinusoidal distribution of windings. A detailed model of a five-phase VSI is presented first in terms of space vectors and the existing technique of utilizing only large space vectors is elaborated. It is shown that this SVPWM method leads to generation of high amounts of low-order output voltage harmonics. Next, a novel SVPWM method is introduced, which enables operation with pure sinusoidal output voltages up to a certain reference voltage value, which is smaller than the maximum achievable with the given DC link voltage. To enable full utilization of the DC bus voltage, two different SVPWM schemes are further developed that can be used to extend the operation so that full utilization of the DC bus is achieved. This unavoidably leads to the generation of some low-order harmonics. These harmonics are however of significantly lower values than when only large vectors are used. A detailed performance evaluation of the existing and newly developed schemes is performed, based on the low-order harmonic content in the output voltages. Simulation results are included throughout the article to illustrate and verify the theoretical considerations.
    Electric Power Components and Systems 02/2006; 34(2):119-140. · 0.66 Impact Factor
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    ABSTRACT: This paper takes a new look at the mechanisms underlying the double-edge pulse-width modulation (PWM) process. It presents a novel way of deriving equations for the spectrum of double-edge PWM using basic mathematical techniques. In the process the underlying nonlinearities that generate the PWM sidebands are identified. Unlike the classical double Fourier series approach, the proposed method of deriving the PWM spectrum does not require the construction of the so-called unit cell. The interaction between this new model of the pulse-width modulator and the regular sampling process is studied, and generalized equations for the Fourier transforms of regularly sampled PWM waveforms are derived. A general solution to the important question of what happens to the PWM spectrum when the PWM reference consists of a summation of signals is presented. It is shown that the addition of reference signals in the time domain results in a double convolution of the PWM sidebands in the frequency domain. As an application of this result, it is shown how new analytic equations for the harmonics of third-harmonic injection PWM and space vector modulation can easily be derived. Finally, the new theoretical results are benchmarked against results from the well-established double Fourier series method.
    IEEE Transactions on Power Electronics 12/2014; 29(12):6762-6778. · 5.73 Impact Factor
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