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

The annual world photovoltaic (PV) cell/module production is growing at almost an exponential rate and has reached 1727 MW in 2005. Building integrated PV (BIPV) projects are emerging as the strongest part of the PV market and grid interactive inverters are a key component in determining the total system cost. Module integrated converter (MIC) technology has become a global trend in grid interactive PV applications and may assist in driving down the balance of system costs to secure an improved total system cost. This paper concentrates on the topology study of the PV MICs in the power range below 500 W and covers most topologies recently proposed for MIC applications. The MIC topologies are classified into three different arrangements based on the dc link configurations. A systematic discussion is also provided at the end of the paper that focuses on the major advantages and disadvantages of each MIC arrangement. These are considered in detail and will provide a useful framework and point of reference for the next generation MIC designs and applications.

/pdf/a-review-of-the-single-phase-photovoltaic-module-integrated-5esytqj7r8.pdf

A Review of the Single Phase Photovoltaic Module Integrated Converter Topologies With Three Different DC Link Configurations

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 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

The development and experimental results of a low-cost 500-W DC-AC power converter for photovoltaic power conversion in residential applications are described. The converter uses low-cost technology usually applied in consumer products. The DC-AC converter is specially designed for operation at a wide DC input voltage range (30-170 V) in order to allow optimal power conversion with an arbitrary number of series connected solar arrays. A step-up chopper is used for MPP tracking and provides a constant 200-V DC link for the following push-pull power converter. This galvanic isolating power converter operates at 100 kHz and controls the current in the mains sinusoidally. A thyristor bridge alternates the current after each half line period. The required auxiliary power is kept below 7 W and is taken from the choke of the step-up chopper. >

Low cost DC to AC converter for photovoltaic power conversion in residential applications

Telecom applications require uninterruptible power supplies for different power levels. If the number of different converter systems should be kept low, parallel operation of inverters is of interest. Thus, a master/slave architecture of an inverter system is presented which allows parallel operation of an arbitrary number of inverter modules by a simple control method. All inverter modules can be equal and no extra overall control unit is needed. The decision, which of the modules becomes master, is made via a single common status line automatically. The output current of the master is used as a command reference current for all slaves. It is shown that the master inverter module is able to stabilise the common output voltage independent of the number of slaves. Furthermore it is investigated how the load current and the reactive filter current is shared by the modules. Apart from results of a simulation, experimental work is presented which confirms the theory.

A simple method for parallel operation of inverters

Single phase uninterruptible power supplies (UPS) employ an inverter for DC to AC conversion. Advanced inverters consist of a full bridge transistor topology and an LC filter. An optimal inverter performance can be achieved if the output voltage is controlled by unipolar pulse width modulation (PWM). The paper describes the influence of the unipolar PWM on the voltages and the current within the inverter. Both frequency domain and time domain are used to evaluate the most important harmonics as well as peak and RMS values of the current and voltage ripple. This results in general equations suitable for the inverter design. In addition, two PWM schemes are compared with respect to EMI problems. Finally, measurements are presented which confirm the theoretical work.

H. van der Broeck

Papers

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

Low cost DC to AC converter for photovoltaic power conversion in residential applications

A simple method for parallel operation of inverters

Harmonics in DC to AC converters of single phase uninterruptible power supplies

Alternative power distribution in residential and commercial buildings