Over the last few decennia, power DC/DC converters have been the subject of great interest due to its extensive increment of utilization in different applications. A thorough review on recent developed power DC/DC converters is presented in this paper. The study is focused on the topologies in different applications such as renewable energy, automobile, high-voltage and medium-voltage DC power systems, telecommunication, etc. In addition, an overview of the modulation techniques, the state-of-the-art of control strategies of well-established converters are discussed. Photovoltaic (PV) systems as the noticeable renewable energy resources generally suffer from poor conversion efficiency with instability and intermittent characteristics. Therefore, DC/DC converter with Maximum Power Point Tracking (MPPT) algorithm is essential to ensure maximum available power harnessed from the PV. Important features of DC/DC converters with MPPT are also figured with various performances. Furthermore, the design and optimization of different parameters are addressed systematically. Finally, the researcher’s future challenges and focusing trends are briefly described. For the next-generation converters design and applications, these are considered in details, and will provide useful framework and point of references.

Recent progress and development on power DC-DC converter topology, control, design and applications: A review

Current mode control (CMC) though offers improved line regulation, phase margin and high bandwidth suffers from high output impedance. Although load regulation can be improved by incorporating an integral gain, it reduces the phase margin and increases the overshoot. The objective of this paper is to achieve improved output impedance without using an integral controller. Incorporating a high pass filter in series with the current sensor in CMC, the closed loop DC gain of a CCM buck converter is shown to be almost independent of the load resistance, thus improving load regulation using a proportional controller only. Improved features of CMC are also retained. Following VMC modeling approach, we develop a method to obtain the small signal model of the proposed scheme, and extended to CMC with an accurate low frequency characterisation. The proposed scheme is implemented on a buck converter, and the theoretical results are validated by experiments.

Improving load regulation in current mode control through inductor current filtering

This paper presents an investigation into the relationship between voltage fluctuation and inter-harmonics in distribution network based on modulation theory. It is verified by Matlab/Simulink simulation and physical tests. The modulation theory, commonly used for analysis of harmonics, is used to analyze the inter-harmonics. A switching function of a rectangle waveform is used to describe a diode or thyristor's commutation status. The input current and output voltage of the rectifier can be described by the final waveforms of some sine function modulated by the switching function. And the inter-harmonics characteristics can be obtained by the Fourier analysis of these waveforms. It can be proved that if there are some fluctuations in the voltage source, there will be abundant inter-harmonics in the current. In order to investigate the validity of analysis and simulation, the physical experiments are finished with electric interruption generator (IG).

Correlation Study of Voltage Fluctuation and Inter-Harmonics in Distribution Network

This paper describes a damping control method of power converters for suppression of resonance in DC power network. The resonance occurs when a resonant frequency of the DC distribution line coincides with the frequency of the harmonic or interharmonic components generated by the power converters. For detailed investigation, a combined system which consists of a pulse-width modulated (PWM) rectifier and a PWM inverter is treated as the simplest example. To suppress the resonance, a DC-side damping control method is proposed and its implementation and design method are discussed in detail. Then, the proposed damping control method is applied to the combined system of a PWM rectifier and a PWM inverter. Experimental results verify the validity and practicability of the proposed damping control method. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

A DC‐side damping control method for power converters to suppress resonance in DC power network

Abstract Efficiency in the industrial sector is a priority when seeking to minimize production costs and reduction in losses. Harmonic generation and associated losses need to be treated carefully with broad implementation of variable speed induction motor applications. The effect of these induced losses can add up to a significant loss. This study uses statistical tools alongside synthesized models to deduce and compare outcomes from regulated and unregulated converters in which harmonics may be triggered by switching algorithm of modern switch-mode power supplies and other inductive loads attached to supply bus system. These harmonics accumulate over time due to losses propagating through connected equipment when changes occur on the bus system. In this regard, results obtained from investigating and comparing three original equipment manufacturer variable speed drives that were exposed to voltage unbalance and complex harmonic conditions are presented in this study. A conclusion accomplished from the investigation and comparison suggests that generation of 6-pulse uncontrolled rectifier losses is negligible. Experimental validation confirms that unregulated 6-pulse converter produces on average more harmonics compared to the regulated converter of standard as recommended in guideline to permissible harmonic tolerance. 

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Harmonic generation of variable speed drive under complex-voltage unbalance conditions

The effects of interharmonics, which are defined as non-integer multiples of fundamental or switching frequencies in power utility connected VSI/CSI systems, are different from integer harmonics. A new approach is proposed in this paper based on the "non-linear modulator" concept to describe the generation of harmonics and interharmonics in generalized power converters. Subsequently, the analytical model is concluded and analyzed for conventional d-q rotating reference frame controller in VSI converter. Moreover, effects of feedback control strategy and additional compensation blocks are considered. Analysis validation is also confirmed by simulation results.

Harmonics and interharmonics in general VSI/CSI inverters: analysis, modeling and simulation

DC/DC switching converters have been used in many applications in recent years The sliding mode control based on VSS (variable structure system) theory has been examined for all switch mode converter types, whilst current mode (CM) control scheme is particularly applied to DC/DC converters However, these control strategies can't compensate for large load current and input voltage variations In this paper, a new control strategy by compromising both schemes advantages and avoiding their drawbacks is proposed, analyzed and simulated; and derivation of a dynamic current reference is also carried out Moreover, considerations for realization with DSP controllers are addressed

Y.Q. Lang

Papers

Harmonics and interharmonics in general VSI/CSI inverters: analysis, modeling and simulation

New control strategy for high power DC-DC converters under large load and input voltage variations