The aim of this paper is to present a review of current control techniques for three-phase voltage-source pulsewidth modulated converters. Various techniques, different in concept, have been described in two main groups: linear and nonlinear. The first includes proportional integral (stationary and synchronous) and state feedback controllers, and predictive techniques with constant switching frequency. The second comprises bang-bang (hysteresis, delta modulation) controllers and predictive controllers with on-line optimization. New trends in current control-neural networks and fuzzy-logic-based controllers-are discussed, as well. Selected oscillograms accompany the presentation in order to illustrate properties of the described controller groups.

Current control techniques for three-phase voltage-source PWM converters: a survey

A space vector concept for deriving the switching times for pulsewidth-modulated voltage source inverters is compared with the conventional sinusoidal concept. The switching times are deducted from assumptions for minimum current distortion, the resulting mean voltage values are shown, and the differences between these and the established sinusoidal PWM (pulse-width modulator) are elaborated. Based on an analytical calculation the current distortions and torque ripples are evaluated and compared with the values obtained with the conventional method. The space vector representation results in lower current harmonics and possibly a higher modulation index. A modulator based on an 8086 microprocessor has been implemented, and its performance is reported. >

Analysis and realization of a pulsewidth modulator based on voltage space vectors

This chapter gives a description and overview of power electronic technologies including a description of the fundamental systems that are the building blocks of power electronic systems. Technologies that are described include: power semiconductor switching devices, converter circuits that process energy from one DC level to another DC level, converters that produce variable frequency from DC sources, principles of rectifying AC input voltage in uncontrolled DC output voltage and their extension to controlled rectifiers, converters that convert to AC from DC (inverters) or from AC with fixed or variable output frequency (AC controllers, DC–DC–AC converters, matrix converters, or cycloconverters). The chapter also covers control of power converters with focus on pulse width modulation (PWM) control techniques.

https://www.springer.com/cda/content/document/cda_downloaddocument/9781447151036-c2.pdf?SGWID=0-0-45-1404710-p175009438

Fundamentals of Power Electronics

This paper comprehensively analyzes the relationship between space-vector modulation and three-phase carrier-based pulse width modulation (PWM). The relationships involved, such as the relationship between modulation signals (including zero-sequence component and fundamental components) and space vectors, the relationship between the modulation signals and the space-vector sectors, the relationship between the switching pattern of space-vector modulation and the type of carrier, and the relationship between the distribution of zero vectors and different zero-sequence signal are systematically established. All the relationships provide a bidirectional bridge for the transformation between carrier-based PWM modulators and space-vector modulation modulators. It is shown that all the drawn conclusions are independent of the load type. Furthermore, the implementations of both space-vector modulation and carrier-based PWM in a closed-loop feedback converter are discussed.

https://u.dianyuan.com/bbs/u/26/1109124433.pdf

Relationship between space-vector modulation and three-phase carrier-based PWM: a comprehensive analysis [three-phase inverters]

A direct induction machine torque control method based on predictive, deadbeat control of the torque and flux is presented. By estimating the synchronous speed and the voltage behind the transient reactance, the change in torque and flux over the switching period is calculated. The stator voltage required to cause the torque and flux to be equal to their respective reference values is calculated. Space vector PWM is used to define the inverter switching state. An alternative approach to deadbeat control for use in the transient or pulse-dropping mode is also presented. An alternative modulation scheme is presented in which transient performance is improved by specifying the inverter switching states and then calculating the required switched instants to maintain deadbeat control of the flux while reducing the torque error during the entire switching interval. A similar approach is used for a transient in the flux. The implementation of the control scheme using DSP-based hardware is described, with complete experimental results given. >

Direct torque control of induction machines using space vector modulation

A novel analysis is presented of the harmonic content of current, torque pulsations, and harmonic copper losses of a three-phase induction machine fed by a two-phase pulsewidth modulation (PWM) inverter. The purely analytical results are based on the assumption that the switching frequency is high compared with the fundamental frequency. It is shown that the results hold accurately for frequency ratios f/sub s//f/sub 1/>9. >

Analytical analysis of the harmonic effects of a PWM AC drive

Discrete pulse modulation strategies such as delta modulation and sigma-delta modulation have been used in power electronics for more than a decade. They have gained more interest recently because they perfectly match the requirement of resonant link converters to restrict switchings to discrete points in time. The spectral performance of a sigma-delta modulator is calculated analytically without requiring complex mathematics. For the case of a DC input, the spectral components of the modulator output are given as closed-form expressions. For rectangular voltage pulses, the harmonic content of the output current in an inductive load is derived in closed form for both DC and sinusoidal inputs. The results are compared with similar expressions for PWM. >

http://ieeexplore.ieee.org/iel2/568/4228/00162700.pdf

Calculations on the spectral performance of discrete pulse modulation strategies

Several papers have described the use of GTOs in zero current switching (ZCS) applications, with the goal of increasing the frequency range for medium- and high-power converters. Zero current switching with GTOs can be applied in series and parallel resonant converters, as well as in PWM inverters with commutation aid networks. The voltage and current waveforms at the devices differ in each of these applications, and different modes of ZCS can be identified. In this paper, a comparative view of the behavior and characteristics of the GTO in the different modes of ZCS is presented. The variety of ZCS waveforms is described and transferred into a unifying schematic. The behavior of GTOs in the different modes of operation is characterized, and requirements to the circuit environment are pointed out. The relations between the most important circuit parameters and some of the device waveform parameters are investigated experimentally. >

Characterization of GTOs under different modes of zero current switching

A low-loss snubber circuit is presented that works in a 200 kVA GTO (gate-turn-off) inverter at a 540 V DC link and uses a self-oscillating DC-to-DC converter for energy recovery. Experimental results showing the simplicity, efficiency, and reliability of the device are reported. The DC-to-DC converter is investigated in detail. >

H.-C. Skudelny

Papers

Analysis and realization of a pulsewidth modulator based on voltage space vectors

Analytical analysis of the harmonic effects of a PWM AC drive

Calculations on the spectral performance of discrete pulse modulation strategies

Characterization of GTOs under different modes of zero current switching

A regenerative snubber for a 200 kVA GTO-inverter