International Journal of Power Electronics and Drive System (IJPEDS) Vol. 9, No. 1, March 2018, pp. 240~251 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v9.i1.pp240-251  240 Journal homepage: http://iaescore.com/journals/index.php/IJPEDS Small-Signal AC Model and Closed Loop Control of Interleaved Three-Phase Boost Converter H.V.Gururaja Rao 1 , Karuna Mudliyar 2 , R.C.Mala 3 1,3 E&E Department, Manipal Institute of Technology, MAHE, Karnataka, India 2 Modelling Engineer, Knorr-Bremse Technology Centre India, Pune, India Article Info ABSTRACT Article history: Received Dec 4, 2017 Revised Dec 31, 2017 Accepted Feb 11, 2018 Renewable energy sources are increasingly being used today and solar energy is the most readily and abundantly available energy source. Boost converters are an integral part of any solar energy system. In order to obtain maximum possible energy from the solar system multi-phase interleaved boost converters are used. This paper presents the small-signal ac modelling and closed loop control of three-phase interleaved boost converter. State– space modelling methodology has been adopted to have linearized equivalent model of the boost converter. The interleaved three-phase boost converter is averaged over its one switching period and perturbed with small ac variations and finally linearized around its quiescent point to have a small signal ac model. Type III compensator is employed to improve the frequency response and closed loop control of three-phase boost converter. The controller design procedure is discussed in detail. The effect of right-half plane zero in non-minimum phase system and the appropriate pole-zero placements to overcome the maximum phase lag in such system is discussed. The compensated closed loop system is tested for load variations to observe the transient response. Keyword: Three-phase boost converter State-space modelling Type III compensator Voltage mode control Copyright © 2018 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: H.V.Gururaja Rao, Departement of Electrical and Electronics Engineering, Manipal Institute of Technology, MAHE, Manipal Udupi district, Karnataka state, India. Pin: 576104. Email: gururaj.rao@manipal.edu 1. INTRODUCTION DC to DC converters are widely used in photo voltaic systems as a power interface. Rather than conventional boost converters, multiphase boost converters are preferred since they offer several advantages that are very desirable in low voltage and high power applications. First, several parallel power stages are added in parallel to the conventional dc-dc converter to attain multi-phase boost [1], [9]; it increases the power rating and current handling capability of the converter. Second, due to interleaved switching scheme, effective pulse frequency is increased by number of phase times and it also reduces the magnitude of inductor ripple current flowing into the filter capacitor, thereby reducing the size of the filter [2], [5]. Most of the dc-dc converter application systems demand its output to be held constant, in spite of variations in input or load [3]. It can be achieved by designing a control circuit that changes the duty cycle ratio, so as to maintain the output voltage constant and is equal to the desired reference voltage. In addition to regulating the output voltage, the feedback system should be stable, and the transient response should meet the desired specifications.Thus, the foremost objective of a typical DC-DC converter is to maintain its output voltage constant, in spite of disturbance in input voltage, load current and any parasitic effect of circuit elements. So, it is utmost important to adjust the duty cycle to keep output voltage constant .The negative feedback control technique is adopted to feed the sensed output voltage to the controller which in turn varies the duty cycle to regulate the output voltage. [3].