Modeling and adaptive control of modified LUO converter

Microprocessors and Microsystems 71 (2019) 102889

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Microprocessors and Microsystems journal homepage: www.elsevier.com/locate/micpro

Modeling and adaptive control of modified LUO converter Sivakumar Arumugam∗, Premalatha Logamani a

School of Electrical Engineering, Vellore Institute of Technology, Chennai-600127, India

a r t i c l e

i n f o

Article history: Received 27 May 2019 Revised 19 August 2019 Accepted 6 September 2019 Available online 6 September 2019 Keywords: LUO converter PI controller Fly back converter Voltage lifting technique

a b s t r a c t This study presents the implementation and modeling of adaptive control of a modified LUO converter which eventually result in the progression of the dynamic functioning of power converter. In general, LUO converters include two series, which are major and additional series. DC-DC conversion has been executed to employing LUO converter and fly back converter. It uses VL technique in order that output voltage is intensified in every stage. The most important advantages of the proposed structure are that it has the benefits of the switched capacitor and as well VL technique. PI Controller has been used in order to simulate the experimental set-up. Embedded C programming was employed to create the PI controller set up. Kp and Ki values have been calculated using the Ziegler Nichols technique. Simulation has been done using MATLAB. Boosting has been accomplished using the voltage lifting technique. Findings emphasized that LUO converters are likely to improve the power transfer gain in energy progression. Also, the proposed LUO converter in the research has been proven to be able to provide a topology which eventually lessens the output ripple and losses. To verify the proposed DC-DC power converter performance, the simulation and experimental setup has been tested with certain parameters, including source voltage and current, capacitors, etc. Several forms of LUO converter voltage lifting (VL) methods performance including ultra-lift, re-lift and self-lift have been compared with that of the performance of the proposed design. Comparison between different voltage gains of LUO converter topologies have also been carried out in this research. The results reveal that the proposed design gives better boost in voltage, compared with that of the existing designs. © 2019 Elsevier B.V. All rights reserved.

1. Introduction

1.1. Background of the study

The DC to DC technique is one of the most important topics of research in the field of electronics. The voltage of DC delivered by battery comprises of high-voltage current and it is not stable enough, therefore it is not relevant for the majority devices including electric-vehicle controller. The converters of DC-DC are used extensively in hardware circuits and industrial products. This study puts forward the ripple free and steady output of electrical energy from the model of advanced topology of DC-DC converter. In this recommended design the added filter component in the LUOconverter resolve the ripples of output and efficiently improve the level of output energy. This advanced converter of DC-DC is right and suitable to be used into components of electric vehicle with reduced current. The highly developed augmentation techniques of DC-DC converter, for example, LUO converter has been employed in the current study. The underlying principle is to reach the high effectiveness, simple systems and increased power density.

In the electronic system field, the technique of conversion is regarded as one of the most important topics of research. The equipment’s employed for techniques of conversion are identified to have applications in R&D, engineering, several firms and in everyday life. All the feasible converters of DC/DC are regarded to deal with the necessities of certain applications. The DC-DC converter topologies converter can be classified into two main parts relying on whether or not they have galvanic separation between the output circuitry and input supply. There are various types of DC-DC converter topologies used. The below Fig. 1 shows the classification of various types of topologies of DC-DC converter: A power converter that steps up the voltage input and step down the current input is one of the types of boost DC-DC converter. Another type is interleaved four phase boost DC-DC converter topology which permits reducing the input current ripples and output voltage ripples and the voltage ratio is stepped up above 4 times. Another type is buck boost DC-DC converter which permits the input direct current voltage to be either stepped down or stepped up relying on the duty cycle. There are many

∗

Corresponding author. E-mail addresses: [email protected] (S. Arumugam), premalatha.l@vit. ac.in (P. Logamani). https://doi.org/10.1016/j.micpro.2019.102889 0141-9331/© 2019 Elsevier B.V. All rights reserved.

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Fig. 1. DC-DC converter topologies classification. Source: Chakraborty et al., 2019.

more types of DC-DC converter topologies which can be discussed briefly. A LUO converter largely includes two series, i.e. main and additional series. The conventional LUO converter circuit drawing and its function at on and off function is the fundamental LUO converter switched device. One of the products that employ boost converter is Hybrid electrical vehicle. The traditional step-up converter could be reinstated by the projected system [4] in order that consistent function could be accomplished. In this system the LUO converter is of switched capacitor category. It positively contributes to give regulated output electrical energy from an unregulated electrical power supply resource (Dhamodharan, [5]. In the existing technique, the traditional step-down converter for electrical vehicle applications never addresses the load prerequisite comprising more currents on the parasitic capacitances and output voltage. To deal with this issue the highly developed LUO-converter technology of DC-DC has come into limelight. LUO converter is an advanced converter obtained from the step-downconverter.LUO conversion technology becomes the most important subject area in the electronics field, and has been in development over last six decades. Along with its developed growth ratio, the DC-DC converter market is experiencing changes on account of two most important inclinations in the field of electronics like high density of voltage and low electrical energy. A simple conversion of energy, the trouble-free DCDC converter is an electrical divider of energy, however it transmits only output voltage lesser than the voltage of input with reduced effectiveness. The regulators of DC-DC are used to assuage the ripples irrespective of a change in the input voltage or load power. Besides, the LUO step-down converter’s output stage is composed of an electrical device and an inductor. The output stage saves and releases electrical power to the load, and stabilizes the power of switch node to generate a steady output voltage Manikandan and Vadivel [15]. High boost DC-DC converter circuit is considered essential for various applications for example FCV, HEV to increase the electrical energy to advanced level. One of the main blockades within HEV (hybrid electric vehicles) is the circuit of DC-DC for secondary electric loads. Modeling is the interpretation of physical performance by statistical means. Once essential understanding has been achieved, model could be processed to comprise several of the formerly neglected phenomenons. The most generally employed modeling methods of converters are: state space averaging and circuit averaging method. Various positive super-lift converter circuits are equated with the traditional step-up converter and their output voltage currents are assessed. In general, ripples are extremely less in simple LUO converter and comparatively pressures on the switches are greater than the voltage lift LUO converter. A familiar approach which is widely applied in the design of electronic

circuit is the Voltage lift technique. Since the impact of parasitic elements restricts power transfer efficiency and output voltage of DC-DC converters, the voltage lift technique opens a better way to develop circuit features. After research of long term, this technique has been applied for DC-DC converters successfully. LUOconverters are a set of new step boost DC-DC converters, which were evolved from prototypes using the technique of voltage lift. These converters perform positive to positive increasing conversion of DC-DC voltage with greater density of power, cheap topology and high efficiency in simple structure. They possess greater output voltage with little ripples. Therefore, these converters will be used widely in industrial applications and computer peripheral equipment, particularly for projects of greater output voltage. The greater voltage gain can be accomplished easily, but the use of SC technique has been limited particularly because of greater current stress between capacitors during switching. On the other side the parasitic elements limited the power transfer and output voltage gain density and efficiency. To resolve this limitation, the Voltage Lift technique was established. In the voltage lift technique that is evolved using capacitors, inductors and DC—DC converters have most essential part in converter operation and could develop the converter features. The super lift LUO Converter has the benefit of huge gains using statistical series and the drawback of this specific converter is that it is intricate to design on account of complication to essential circuits. Similarly, benefit of LUO converter circuit relifts is that it entails increased power density and effectiveness and the drawbacks involves intricate circuit and the circuit becomes huge (Jayachandran, et al. [7]. LUO Converter has been evolved rapidly, and it is used widely in computer peripheral equipment and industrial applications. 1.1.1. Applications of welding In welding case, the harshness of the arc and ease of starting is decided by electrical importance (volts) i.e. the voltage is related directly to the length of arc. Hence this developed LUO converter can be used for applications of welding needing big arc. 1.1.2. Industry of cement manufacturing In the industry of cement manufacturing, the crushing process of raw materials like gypsum needs greater voltage. This need can be fulfilled by using the proposed scheme as it offers greater voltage than twice the input. 1.1.3. Hybrid electric vehicle One of the applications which uses boost converter is the hybrid electric vehicle. The conventional boost converter can be changed by the proposed scheme so that the reliable operation can be accomplished.

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1.1.4. Electrophoretic deposition The phrase which is used for vast number of industrial processes which involves cathodic electro-deposition, electrocoating, electro-phoretic coating, electrophoretic painting and anodic electro-deposition. Usually the 25V DC to 400V DC is utilized in electro-phoretic painting or electro-coating applications. The proposed system can fulfill this need conveniently.

2. Review of literature

1.1.5. Railway electrification and tramway system Generally the supply of power ranges from 600 V DC to 4.3 KV DC which is needed for the railway electrification and tramway system

Chilambarasan, et al. [3] stated that the technique of voltage lift is considered as a familiar methodology, which is extensively used in the design of electrical-circuit. The consequence of scrounging elements restricts the voltage of output and electrical power transmission effectiveness of the converters of DC-DC. This method opens a reliable way to enhance circuit features. The advancement of new boost converters of DC-DC is the LUO-converters, which have been established from models employing voltage lift technique. In the present study, four converters in addition to voltagelift circuit are examined, which involves positive and negative output elementary LUO converter, positive and negative output selflift LUO converter. All these LUO–Converters executing the system of voltage lift hinder taking increased value of the duty k transmission. For the equal value of duty cycle intensified output power is comparatively acquired for self-lift LUO converters than the uncomplicated LUO converters. As well the values of electrical device and electrical condenser are inferior for self-lift than the elementary LUO converters. Simulation results of the study are considered to emphasize the virtues and values of the converters. Madhappan et al. [13] has mentioned in their study that the technique of voltage lift is a familiar approach which is used widely in the design of electronic circuit. The parasitic elements effect restricts the efficiency of power transfer and output voltage of DC-DC converters. The technique of voltage lift opens a better way to develop the features of circuit. The LUO converters are a set of new step up converters of DC-DC which were evolved from prototype using the technique of voltage lift. In this study Four Voltage lift circuit converters are examined namely elementary LUO converter of negative output, self-lift LUO converter of negative output, elementary LUO converter of positive output and self-lift LUO converter of negative output. These converters indicate greater voltage of output with little ripples along with greater efficiency, easy structure and greater density of power. These converters are used vastly in industrial applications and computer peripheral equipment particularly for projects of high output voltage. These converters can be utilized for different photovoltaic applications. Sujatha et al. [21] has stated that among the feasible resources of renewable energy the photo voltaic and wind energy is used widely because of their sustainability and abundance to produce electricity. In this study a new hybrid combined topology fed by alternating current supply and solar energy is designed using LUO converters positive and negative output. This design permits the two sources to provide the load individually or together simultaneously relying on the feasibility of sources of energy. The main aim of this hybrid is to meet their daily demand efficiently and to acquire an uninterrupted supply of power. By integrating these two intermittent sources the reliability and power transfer efficiency of the system can be developed essentially. Due to the multi input converters inherent nature extra filters are not essential to filter out greater harmonic frequency and hence a developed output voltage with little ripples is acquired. The results of simulation provide the advantages of the proposed circuit. Mehta and Haque [16] has mentioned in their research that direct current voltage offered by battery comprises high voltage ripples and it is not steady enough thus it is not useful for several devices like electric vehicle controller. The DC-DC converters are used to reduce ripples irrespective of alteration in the voltage of

1.1.6. Other applications Electrically powered vehicles of rail namely electric locomotives and electric multiple units, conveyors, elevators and battery operated electric vehicles. The positive output of the simple super lift LUO circuit is considered as a new chain of converters of DC-DC having greater voltage gain of transmission, high volume power density, developed effectiveness and lessened current voltage. These converters are extensively employed in PC hardware, switch-mode power supply and industrial products, particularly for increased projects of voltage-voltage. In addition, the super-lift technique intensifies the power transfer gain in every stage in geometric progression to a large extent (LUO, 1998). A simple LUO converters positive output that performs the output voltage intensifying in geometric series with an elementary structure have been established (LUO, 2003). In addition, these converters efficiently develop the gain of power transfer in power-law conditions. The structure of increased operation control for them is not an easy task for control-engineering and as well power electronics engineers. Generally, a high-quality control for DC-DC converters ensures solidity in subjective operating condition. The positive output simple converter of LUO with controls of PI consequently requests its usage in operations for instance peripheral equipment of computer, medical and industrial applications, particularly for voltage projects, which is in high range [11]. DC-DC converters get extensive applications in standardized supplies of switch-mode DC energy and in drive operations of DC motor. The switched mode resources of energy are nonlinear time changeable systems and therefore the structure of increased performance control is generally a complicated thing for engineers, particularly electronics engineers. A large deal of attempt has been instructed in developing the prototype and several DC–DC converters control systems. As a result of the switching action the step-up converter circuit has non-linear conduct; it becomes essential to acquire a non-linear paradigm of the system. At present, the technique essentially employed in power electronic study is the statespace averaging method. As a result of undershoot there is a deferral in attaining the stable state, undershoot control intensifies, greatest limit on the attainable closed loop gain is required and restricts the bandwidth as the closed-loop gain intensified to control the output energy the control techniques become unsuccessful to give desired reaction. In order to prevail over these undesirable impacts created by undershoot inappropriate control method is essential as pointed out by Sundaramoorthi, et al. [22]. 1.2. Research objectives i. To explore the existing techniques for designing LUO converters ii. To identify the flaws in the existing LUO converters iii. To model and implement a novel LUO converter design and compare its performance with that of the existing designs in terms of voltage gain and controller performance.

This section deals with existing research work on LUO converter designs. This section also presents a comparative study of different versions of LUO converters. 2.1. A review of existing research work on LUO converter designs

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load. In the already existing approach for electric vehicle applications the classical buck converter does not meet the needs of load comprising more number of ripples on voltage output and impacts of parasites. To resolve this issue the advanced LUO converter technique of DC-DC is established. The LUO converter is the evolved converter derived from buck boost converter. This study suggests the ripple and stable free output voltage from DC-DC converter topology design. In this proposed approach of LUO converter the extra element of filter remove the ripple output and develop the output voltage level effectively. Subasri and Govindaraju [20] present a LUO converter design derived from LED driver. With moderate components parameters model, the suggested converter could achieve soft-switching features, which extremely lessen switching losses and enhance the system effectiveness. The conversion of DC-DC is considered as having greater importance in LED based circuit. DC-DC conversion could be consistently functioned employing LUO converter. It uses the technique of voltage lift in order that the output voltage is intensified in every stage. In the present study, the recommended LUO converter has been exhibited to offer a topology that eventually reduces the output current and losses. The findings of simulation explained the computations and design. The voltage lift technique provides a virtuous way is enhancing circuit quality and has been effectively used for DC-DC converter. LUO converter circuits are DC-DC boost converter employing only one switch. The most important advantages of this projected scheme are that it blends the advantages of voltage lift method, switched capacitor and the electric resistance network. Jose and Jayanand [9] pointed out that voltage lift technique is a widespread process broadly employed in the design of electrical circuit. The voltage steps up every stage along with the statistical progression. On the contrary, by a circuit of super-lift converter, the output steps up in every stage alongside a geometric growth. Therefore, it effectively develops the transfer gain in electrical series. This study exhibits that the PI control progression provides increased static and dynamic performance. The MATLAB software is employed to examine the dynamic features and examine the closed-loop functioning circuits with resistive load and load turbulences resistive load in supply. The DAC card is employed for the application of positive output of hardware of simple LUO converter and its proportional integral (PI) control. The experiential and simulation findings complement strongly with one other and emphasize the practicability and strength of the developed control system. Jeong, et al. [8] introduces a SAC (simple adaptive control) technique to deal with a strong performance contrary to load deviation of a step-up converter system of DC/DC voltage. To employ the algorithm of simple adaptive control the controlled plant transmission operation must be almost strictly positive real (ASPR).As the circuit of converter does not have almost strictly positive real, a technique known as parallel feed-forward compensator (PFC) is needed to execute the simple adaptive control algorithm. To begin with, the study designs a PI controller and formulates a series relation with the linearized nonlinear model of the voltage converter at the working point. Subsequently a stabilizing PD controller is being composed for the connected system. Contrary to the acquired PD controller is employed for the PFC, which makes the parallel-connected technique to be ASPR. Computer simulation findings exhibit the efficiency of the proposed control algorithm. The simulation results of the study exhibit that the proposed control assures the control of output voltage efficiently within the load uncertainty. Arikatla, [1] investigates the development and execution of adaptive control techniques, which bring about the development of the dynamic performance of electrical energy converter, by using the adaptability of digital controllers to comprehend highly devel-

oped control schemes. Four various techniques are formulated that enhance the overall performance of converter without negotiating the steady-state operation. Similarly, a Sensor less Adaptive Voltage Positioning (SLAVP) has been expressed so as to accomplish Adaptive Voltage Positioning (AVP) control devoid of the demand for high-speed Analog-to-Digital Converter (ADC) system and inductor voltage sensing. The eradication of the demand for prompt and precise sampling and sensing of power employing the recommended Sensor less Adaptive Voltage Positioning control lessens the digital controller volume and outlay. AVP (Adaptive voltage positioning) has been utilized in DC-DC converters of switching power for powering integrated circuits due to its benefits of using permitted tolerance of output voltage while reducing the capacitance need of output filter and accomplishing rapid transient response. Several control schemes of Adaptive voltage positioning in the published literature needs sampling circuits and current sensing which raises the size, complexity, cost, and can cause inaccuracy of Adaptive Voltage Positioning operation. A Sensor less Adaptive Voltage Positioning controller of DC-DC boost converter is proposed presently which can accomplish Adaptive Voltage Positioning control based on the linear relationship between the duty cycle value and output current value while utilizing the value of duty cycle as current value indicator. However, this Sensor less Adaptive Voltage Positioning control scheme cannot be applied to DC-DC boost converter topology directly because of two reasons. One is the Right Half Plane zero of boost converter which generates issues in system stability and effects of ringing during light to huge load transients. Second, the link between the duty cycle value and output current value of the DC-DC boost converter is nonlinear. This paper suggests a linearized sensor-less Adaptive Voltage Positioning (L-SLAVP) control scheme which resolves the second problem effectively. In addition, an Adaptive Digital PID (AD-PID) controller scheme has been suggested so as to enhance the active performance of electrical converters. LUO and Ye [12] studied the LUO converter design. The voltagelift (VL) methodology has been used efficiently in power DC/DC converters pattern. The LUO-converters with three series is considered as the fine example of this. Employing the VL technique could possibly provide high-voltage gain of transfer. The superlift system has been received a lot of attention as it makes gain of high-voltage transfer available. The LUO-converter is established as a distinctive novel method to the advanced technique, ultra-lift system that generates even increased gain of voltage transfer. The computation and analysis mentions the advanced features of converter. Chand and Ramesh [2] pointed out that, in recent times, using of the DC-DC converters are gradually increased as a result of the enormous applications like locomotives and in those converters, comparatively LUO converters are considered as the highly developed technology than elementary converters and voltage-lift circuits. A novel design i.e. customized positive output LUO DC-DC converter is formulated in this study in order to step up the gain and output power equate to standard super-lift LUO converter. VLbased converters will make gain in arithmetic progression on the contrary super lift converters are likely to step up the gain in geometric series. The photovoltaic array engenders DC voltage by using sun’s irradiation and high temperature. Each of these converters is expected for the 10 kHz frequency. For all the above stated converters the simulation models with control stratagem are formulated by using the software of MATLAB. And the performance outcomes are formed to recognize the best converter. 2.2. Research gap This study has discussed mainly about the different design versions of LUO converter. The Table 1 gives the review of existing

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Table 1 Findings of the review of existing LUO converter designs. S. No

Author

Findings

1

Prasanna, et al. [17]

VL technique has been extensively employed in electronic field as a result of the parasitic capacitance consequence, the energy transmission and output voltage effectiveness of all DC-DC converters is constrained. Additional to this, VL technique has its drawbacks as well, for example the output voltage intensifies in arithmetic series. With its progression, LUO converter is proven to be effective.

2

Karthick, [10]

LUO converters have no parasitic capacitance on account of VL methodology and the converters output voltage is boosted with the assistance of inductor and capacitor collection in order that intensification in the gain and voltage

3

Mahalakshmi and Nammalvar [14]

The author proposed new approach of ultra-lift LUO converter and executed for electric vehicle in order to keep up the steady DC output with moderated current. The findings emphasized that the proposed system, i.e. ultra-lift LUO converter provides increased effectiveness, low voltage current than super-lift converter and VL technique.

4

Sagar, et al. [18]

This project explains a various technique of a highly developed DC-DC converter for non-conventional sources of energy, which could be used even in low-power machines as wireless sensors. As well, additional benefit of LUO converter is that the factor of switching power is positioned to ground, facilitating the switch as uncomplicated to drive.

5

Tekade, et al. [23]

Designs of LUO converters are largely convenient and considered effective for high output voltage products over the decade. Similarly, these converters are likely to improve the voltage transfer gain efficiently to a certain extent.

designs of LUO Converters with their functionalities. The LUO converter is capable of offering a topology that decreases the parasitic effects and output ripple effects. The DC-DC converters are convenient and suitable to be used into applications of electric vehicles with little number of ripples. The DC-DC converter increases the transfer of energy between low voltage and high voltage side providing huge benefits in terms of reduced cost, reliable, efficient and flexible converters. The rapidly effective DC-DC converters must be utilized to offer proper levels of voltage and the management of power between various sources of level of energy and storage elements. The proposed LUO converter in this study resolves the parasitic issues present in DC-DC converter. The main aim of this study is to reduce the efficiency and enhance density of power.

Fig. 2. Circuit diagram of the proposed LUO converter design with isolated transformer.

3. Methodology The technique of VL has been effectively used in the DC/DC converters design. Unlike previous studies, this study introduced a novel approach of LUO converter with Fly back converter, which is referred to as Modified-LUO converter. The study includes, circuit design, comparisons between circuit performance and implementation. The proposed converter presents high output gain with low amount of input DC voltage. Fly back converter in general is considered having high voltage input. The study intends to choose fly back converters for its simple design and low cost. The study uses PI control algorithm and performs closed loop voltage operation with variable input voltage. MATLAB simulation is used in this study to verify the proposed technique performance and findings are verified with the simulation results. DSPIC30F2010 controller has been used to develop the hardware.

Fig. 3. Modes of operation of the proposed LUO converter (mode 1).

3.1. Modeling - Circuit configuration and operation analysis The circuit consists of an isolation transformer (Ts ), four Diodes (D1 , D2 D3 ) and two capacitors C1 and C2. The converters share among themselves the source and output capacitor C0. The 4 inductors that are similar in the design of a LUO Converter have been changed by an Isolation transformer in the recommended design. The switch S is also available in the design in order to control the voltage flow of the circuit. The circuit configuration of the proposed converter is given in Fig. 2.

Fig. 4. Modes of operation of the proposed LUO converter (mode 2).

Mode 1 The proposed converter operates in two modes. Mode 1 is shown in Fig. 3 and mode 2 is shown in Fig. 4. In mode 1, there are capacitors C1 and C2 operating in parallel to each other.

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Fig. 6. Current flow in mode 1.

Fig. 5. Theoretical waveforms of modes 1 and 2. Fig. 7. Current flow in mode 2.

The equations pertaining to this mode are given as follows.

iLP = VC1 =

Vs Lp

V0 =

iC1 C1

G=

In the second mode the capacitor C2 also is not required since the presence of the second capacitor might make the switch position wrong in the circuit.

VC p VC0 − Ls Ls VC0 its V0 = − C0 RC its = −

Mode 2 Mode 2 of operation of the circuit is depicted in Fig. 4. In this mode, the capacitor C2 is removed and the circuit operates with C1 alone. The equations pertaining to the flow of current in this circuit is given as follows

it p = iC2 + iC1 it p = VC2 =

VC0 −VC1 − Ls Ls VC0 its = − C2 RC0

iC1 = its = iC0

3.2. Circuit mathematical analysis and design Each mode and the theoretical waveforms associated to both the modes have been depicted in the Fig. 5. Mode 1 The flow of current in Mode 1 is portrayed in Fig. 6 as follows. When the switch is turned on condition

iLS

V1 V0 − V1 = dt = (t − d )T LS LS

V0 = Vs

 1  1−d

 1 2 1−d

Vs

ILP = (1 − d )

V0 R

The current flows can be represented as follows

CLP = ILP =

iLS =

VS dt LP I0

(1 − d )2 V1 LS

dt iLS =

I0 1−d

The current variation L1 and L2

S1 =

iLP /2

=

VS dT LP

VS dT (1 − d ) 2LP I0

2

=

ILP 2I0 /(1 − d ) diLP LP = = VS = VLP − VC1 = VLS + VC0 dt VC0 = V0

VC2 Vs − Lp Lp it p C2

1 V1 = 1−d

2

Mode 2 The flow of current in Mode 2 is portrayed in Fig. 7 as follows.

VLP = VS − VC2 VC1 = −(VLS + VC0 ) VC1 − VC0 = VLS − VC1 − VC0 = VLS iC2 = iLP V0 VC0 = iLS − R R = V0 ⇒ iLS = iC1

iC0 = iLS − VC0

Conversion ratio = M(D) =

V0 VS

=

D 1−d

3.3. Scope of the research This study presents the implementation and modeling of adaptive control of a modified LUO converter which eventually result in the progression of the dynamic functioning of power converter.

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Fig. 8. Experimental setup.

Table 2 Circuit parameters of the proposed LUO converter. Components

Symbols

Rating

Source voltage Source current Capacitors Isolation transformer Output load current Switching frequency Output power Switching devices(all) Diodes(all) Driver circuit

vin ii C1 ,C2 ,C3 &C4 N1 : N2

20 V–70 V DC. 11A 10 uf/250 V & 22 uf/350 V 1:3 1 Amps 100 KHZ 750 W IRF250 MUR1560 TLP 250

f P0

The main scope of the study is discussing about the different versions of LUO converter. This study proposes different adaptive control techniques to enhance the static and dynamic energy converters performance. This study has introduced a novel approach of LUO converter with Fly back converter, which is referred to as Modified-LUO converter. The study intends to choose fly back converters for its simple design and low cost. The study uses PI algorithm and performs closed loop voltage operation with variable input voltage. The main aim of the research is that the proposed LUO converter must reduce the output ripple effect. 4. Simulation and experimental results 4.1. Set up of experiment The experimental set up and simulation was verified with similar specifications and parameters in order to verify the proposed DC-DC power converter performance are mentioned below in Table 2: The PWM generation and closed loop control of the proposed converter was carried out by making use of a DSPIC30F2010 microcontroller. This controller comes with a built- in DSP engine and PWM generator which is crucial when it comes to controlling a DC—DC converter topology. A test circuit (driver and re-boost converter) of the proposed converter is implemented. The Fig. 8 shows the experimental view of proposed DC-DC converter. This system is developed using DSPIC30F2010 controller.

An embedded C program was developed to achieve PI control scheme. The program was designed in a way to obtain the values of Kp and Ki estimated by the technique of Ziegler Nichols and utilize this to achieve the level of set voltage at the output. 4.2. Simulation and hardware results The hardware results and simulation of the input DC voltage given to the proposed converter has been depicted by Fig. 9(a) and (b) respectively. The Fig. 10(a) and (b) shows the experimental results and simulation respectively of the input current waveform of the proposed DC-DC LUO converter. The primary winding of the magnetizing transformer inductance maintains the input current as continuous. The Fig. 11(a) shows the PWM pulses applied to the proposed LUO converter. The pulses of PWM are generated by the PI controller. Here the actual voltage from the DC-DC converter and the reference output voltage are compared and then the error is transferred to the PI controller. Then the reference signal and carrier signals are compared to produce the PWM pulses. The duty cycle “a“ can be produced by comparing the dc signal reference Vr with Vcr as a saw tooth carrier signal. The carrier signal ratio to reference signal where the duty cycle can be differed from 0 to 1 is known as Modulation index. To acquire the pulses of square wave the signals are compared by a comparator to produce the difference (Vc-Vcr).Any differences in Vcr differs linearly with “a” duty cycle. A PWM (Pulse Width Modulation) Signal is an approach for producing an analog signal using a digital source. A pulse width modulation signal comprises of two major components that refer its behavior: a frequency and a duty cycle. The duty cycle explains the period of time where the signal is in on (high) state as the total time percentage of it takes to finish one cycle. The frequency indicates how rapid the pulse width modulation finishes a cycle (i.e. 10 0 0 Hz would be 10 0 0 cycles/s), and therefore how rapidly it switches between low and high states. By cycling an off digital signal and a fast enough rate in on state and with some duty cycle, the output will seem to behave like a constant analog signal of voltage when offering power to devices. Example: To generate a 3 Voltage signal given a digital source that can be either low (off) at 0 V and high (on) at 5 V, you can

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Fig. 9. (a). Simulation result of input DC voltage of the proposed converter and (b). Hardware result of input DC voltage of the proposed DC-DC converter.

Fig. 10. (a). Simulation result of the DC-DC converter input current waveform and (b). Hardware result of DC-DC converter input current waveform.

Fig. 11. (a). Simulation results of PWM pulse to the converter and (b). Experimental results of PWM pulse to the converter.

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Fig. 12. (a). Simulation result of current in the diode D1 and (b). Hardware result of current in the diode D1.

Fig. 13. (a). Simulation result of current in the diode D2 and (b). Hardware result of current in the diode D2.

utilize pulse width modulation with 60% duty cycle which outputs 5 V i.e. 60% of the time. If the digital signal is performed fast enough, then the voltage at the output seems to be the average voltage. If the digital low is 0 V (which is generally the case) then the average voltage can be estimated by considering the high voltage multiplied by the duty cycle, or 5 V x 0.6 = 3 V. Choosing a duty cycle of 80% would generate 4 V, 20% would generate 1 Volt, and so on. Closed Loop Algorithm For achieving the closed loop the algorithm used is as follows:

1. Initialize 2. Various registers and pins are configured as per the need 3. Start the module of timer to produce pulses with 0.5 duty cycle. 4. Perform a delay routine so that the output of converter meets its value of steady state output. 5. Output Sample (after stepping it down to an acceptable value by processor) 6. Store the output of ADC in one of the registers and estimate the error (Sample value - Pre-specified value) 7. The output voltage is smaller than the reference value if there is a positive error. So the duty cycle is increased. 8. The output voltage is higher than the reference value if there is a negative error. So the duty cycle is reduced. 9. The steps 4 to 8 are repeated till the output is acquired. 10. Terminate

The experimental results of portrayed by Fig. 11(b).

The Figs. 12(a)–14(a) shows the simulation results of the current flowing through the diodes D1 to D3 of the proposed converter respectively. Similarly, the hardware or experimental results of the current flowing through the diodes D1 to D3 of the proposed converter has been portrayed through the Figs. 12(b)–14(b) respectively The Figs. 15(a)–17(a) shows the simulation results of the capacitor voltage waveforms. The voltage across the capacitor C2 is equal to the input voltage. Likewise, the hardware results of the capacitor voltage waveforms are given by Figs. 15(b)–17(b) respectively. The Fig. 18(a) and (b) respectively shows the simulation and hardware results of the output voltage waveform. The PI controller maintains a constant output voltage with given input voltages. The Fig. 19(a) and (b) shows the simulation and hardware results of the converter load current waveform.

4.3. Comparison of existing design vs. proposed design The following Table 3 is a comparison between different LUO converter topologies with respect to their components. Number of inductors diodes and switches are given for all the chosen LUO converter circuit. The proposed LUO converter has been visible to be changed by an isolation transformer. Table 4 represents the comparison table between different LUO converter topologies voltage gain.

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Fig. 14. (a). Simulation result of current in the diode D3 and (b). Hardware result of current in the diode D3.

Fig. 15. (a). Simulation result of capacitor voltage C1 and (b). Hardware result of capacitor voltage C1.

Fig. 16. (a). Simulation result of capacitor voltage C2 and (b). Hardware result of capacitor voltage C2.

5. Discussion Faster growth in DC to DC converter techniques is experiencing extreme changes as a result of those most important developments including low voltage, high-power density in electronic sec-

tor to certain extent [19]. DC-DC converters have extensive products in regulated supplies of switched-mode DC energy and as well in drive applications of DC motor. In general, LUO converters include two series, which are main and additional series [15]. The proposed LUO converter in the study is proven to be capable of

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Fig. 17. (a). Simulation result of capacitor voltage Co and (b). Hardware result of capacitor voltage Co.

Fig. 18. (a). Simulation result of DC-DC converter voltage waveform and (b). Hardware result of DC-DC converter voltage waveform.

Fig. 19. (a). Simulation result of DC-DC converter load current waveform and (b). Hardware result of DC-DC converter load current waveform. Table 3 Comparison table for numbers of elements among different LUO converter topologies. LUO convertercircuit

No. of inductors

No. of diodes

No. of switches

Elementary Self – lift Re – lift Triple – Lift Proposed

2 2 3 4 Replaced by an isolation transformer

1 2 3 4 3

1 1 2 2 1

11

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Table 4 Comparison table between different LUO converter topologies and voltage gain. LUO converter

I0

V0

Circuit Elementary Self – lift Re – lift Triple – lift Propose boost

I0 = 1−αα Is I0 = (1- α )Is I0 = 1−2α Is I0 = 1−3α Is I0 = 31(2−−αα ) Is

V0 = 1−αα Vs V0 = 1−1α Vs V0 = 1−2α Vs V0 = 1−3α Vs V0 = 3 21−−αα Vs

Vs = 20 V

α = 0.5

α = 0.75

20 40 80 120 180

40 80 160 240 300

offering a topology which eventually lessens the losses and offers a ripple output. In order to verify the proposed system performance, the simulation has been tested with certain parameters, including source voltage and current, capacitors, etc. Besides, the MATLAB simulation has been studied and the comparison between different LUO converter topologies voltage gain has also been carried out. The study also uses fly back converter, which is akin to other converters. But the current study can be considered as unique as it introduces the novel system of LUO converter combined with Fly back converter. Simulation results with theoretical analysis are given in order to validate its performance. Fly back converter has a benefit of an extensive range of transfer ratio that transforms by changing the duty cycle and the fly back converter’s ratio. Converters are developed and simulated employing MATLAB technique. Simulation findings have been performed for different variations in load and input values. The PWM generation and closed loop control of the proposed converter was performed using a DSPIC30F2010microcontroller. The converters of DC-DC are employed in hardware circuits and industrial products to a large extent. The switched-mode power supplies are generally nonlinear time systems and therefore the model of increased performance control is mostly a complicated issue for engineers. The DC-DC conversion technology is turned out to be the most important subject area in power electronics field, and has been in progression for last six decades. Accordingly, a serious attempt has been taken in the study in establishing the control techniques of different DC–DC converters. one of the essential circuits of electronics which are used widely in power electronics. The main issue with the DC-DC converter operation is unregulated supply of power which leads to improper DC-DC converter function. There are different digital control and analogue methods used for DC-DC converters and certain have been used by industry involving the current and voltage mode control techniques. The inputs of DC-DC converter are usually unregulated input of DC voltage and the needed outputs must be a fixed or constant voltage. Different types of voltage regulators with different schemes of control techniques are used to enhance the DC-DC converter efficiency. Nowadays due to the improved technology and advancement in power electronics a much serious need for reliable and accurate regulation is desired. This has led to the requirement for a much reliable and advanced design of controller for DC-DC converters. The different types of DC-DC converters need various kinds of controlling techniques because an individual technique cannot be used to entire converters as all have varied specifications. Thus, it can be justified that every control technology has its own drawbacks and limitations and it relies on their requirement that what type of control technique is required for DC-DC converter. The conversion techniques of LUO Converters and DC-DC converters are advanced very quickly. The simple LUO converter presents step-up operation in DC-DC conversion [19]. The LUO converter of positive output, on the other hand, presents the conversion of load voltage from positive input to positive output. Communication technology has been established very rapidly and demanded low voltage supplies of DC energy for communication. This gave rise to the fast advancement of conversion techniques

of DC-DC. The DC-DC converter empowers the transfer of energy amid the low and high voltage side providing remarkable benefits with regards to low cost, adaptable, consistent and effective, increased as a result of the potential limitations of uncomplicated to make synchronous rectification and execution. The suggested progressed converter of DC-DC is LUO converter, which prevails over the parasitic issues exhibit within the classical converter of DC-DC. In order to verify the performance of the proposed DC-DC power converter, the simulation and experimental setup was tested with the same parameters. Besides, the pulse-width-modulated (PWM) generation and control of closed loop of the proposed converter has been performed using a Dspic30f2010 microcontroller. This controller comes with a build in DSP engine and PWM generator which is crucial when it comes to controlling a DC—DC converter topology. The output voltage is generally directing by regulating the power switch’s on time, which consecutively changes the distance across of a voltage on the output [6], which is referred to as PWM control. MATLAB simulation has also been used to study the proposed system of the current study. MATLAB software is generally employed in order to explore the dynamic features and circuits closed-loop functioning with resistive load in load and supply turbulences [7]. Employing the VL technique will eventually result in transfer gain of high-voltage. The LUO-converter is largely considered as a unique technique to the advanced technology, whereas ultra-lift system that generates even increased gain of voltage transfer. The LUO converters with positive output are obtained from this simple circuit, which include re-lift circuit and self-lift circuit. The broadly employed control techniques for DC-DC converters are PWM control of voltage mode and PI controller. These traditional controllers are not capable to carry out adequately under load variation. Comparison between different LUO converter topologies voltage gain has been presented in the study, which include, Triple – Lift, self-lift and re-lift. The PWM pulses are produced by the PI controller. Comparison takes place between the reference output voltage and DC-DC converter voltage; followed by the inaccuracy rate is transferred to the PI controller. The actual purpose of a PI controller is to obtain the converters output voltage which is assessed and determines it with the reference voltage and as well to create the error signal in order to direct the converter to the preferred value. The most important role of PI controller is to lessen the peak overshoot and formulate stable state error zero. MATLAB model of the Triple-Lift LUO converter has been progressed and from the simulation, error, variation in the cycle of error and duty has been obtained. The findings emphasized that the voltage across the C2 capacitor is equal to the input voltage and the PI controller maintains a constant output voltage with given input voltages. PI control is likely to be a more realistic method that makes sure the right function in any working state to optimize the constancy of positive voltage output LUO converter. 6. Conclusion and future work With the ever-increasing requirement of renewable energy resources, the study formulated self-lift and re-lift series of LUO converter in place of step-up converter that is generally employed in hybrid electric vehicle. The current study proposes various adaptive control techniques to enhance the dynamic and static performance of energy converters. Besides, this study provided the different versions of LUO converters and examines the overall benefits of LUO converters in electrical field. The design of converter circuit along with the application of closed loop scheme requires modeling and followed by simulating the converter employing the developed algorithms. This could easily be accomplished with an assistance of MATLAB as a key for simulation of those algorithms. This research intends at progression of the models for all simple converters and

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investigating its open loop reaction, in order these models could be employed in any close loop scheme. The technique of voltage lift is broadly employed in electronic circuit and as the parasitic elements output lessens the effectiveness of energy transfer and output energy of DC-DC converters, the VL method has been used effectively used for converters of DC-DC, resulting in LUO converters. For DC-DC converters, it is every time sought-after that the output voltage continues unmovable in both stable state and transitory functions every time the supply voltage current is disturbed. And, this condition is popularly referred to as zero-voltage regulation. In the present research, the proposed LUO converter has been revealed to be capable of offering a topology that decreases the parasitic effects and output ripple. In the present research paper, the proposed LUO converter has been exhibited to be able to giving a topology, which lessens the effects of output ripple. Simulation results of this study validate the designs and calculations. The proposed DC-DC converters are expected to be suitable to be used into electronic applications through low ripples. The highly developed DC-DC converter development method for example LUO converter is employed. The most important purpose is to achieve greater effectiveness, high-low power intensity and elementary structures. The development of algorithms for the adaptation of several variables and the optimum value identification, amongst others, is required. This might entail further perspective into optimization concept, which defines the potential means to accomplish the optimal functioning in least number of phases. This work can be extended in future by conducting a detailed loss analysis of the converter topology in order to reach maximum efficiency. The study could also be extended by investigating alternate PWM control methods to reduce switching stress on active devices, modifying the topology to permit high power applications, implementing MPPT controllers to develop the renewable energy based converter for agricultural irrigation and implementation of intelligent controller based algorithm to check the feasibility of the proposed converter. Declaration of Competing Interest This paper has not communicated anywhere till this moment, now only it is communicated to your esteemed journal for the publication with the knowledge of all co-authors. Ethical approval This article does not contain any studies with human participants or animals performed by any of the authors.

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[6] N. Dhanasekhar, R. Kayalvizhi, Performance Evaluation of Negative Output Triple-Lift LUO Converter with Various Controllers, International Journal of Pure and Applied Mathematics 117 (16) (2017) 227–233. [7] D.N. Jayachandran, et al., Modelling and Analysis of Voltage Mode Controlled LUO Converter, American Journal of Applied Sciences 12 (10) (2015) 766–774. [8] G.J. Jeong, et al., Application of Simple Adaptive Control to a DC/DC Boost Converter with Load Variation, Researchgate Publications. (2009). [9] J. Jose, B. Jayanand, Simulation and implementation of superlift LUO converter, in: International Conference of Renewable Energy and Sustainable Energy, IEEE Publication, 2013. [10] Y. Karthick (2016). Modeling and Design of a new LUO converter. Retrieved on 30th April 2019 from https://www.researchgate.net/publication/309187869_ Modeling_and_Design_of_a_new_LUO_converter. [11] K.R. Kumar, S. Jeevananthan, PI Control for Positive Output Elementary Super Lift LUO Converter, International Journal of Electrical and Computer Engineering 4 (3) (2010) 544–549. [12] F.L. LUO, H. Ye, Ultra-lift LUO-converter, in: IEEE Proceedings, 152, 2005, p. 7. [13] C. Madhappan, R. Babu M, R. Sujatha, Design And Simulation of LUO Converter Topologies For Photovoltaic Applications, International Journal of Applied Engineering Research 9 (23) (2014) 21553–21560. [14] S. Mahalakshmi, P. Nammalvar, Implementation of Ultra-Lift LUO Converter for Electric Vehicle Application, International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering 6 (3) (2017) 1968–1975. [15] A. Manikandan, N. Vadivel, Design And Implementation Of LUO Converter For Electric Vehicle Applications, International Journal of Engineering Trends and Technology (IJETT) 4 (10) (2013) 4437–4441. [16] N.D. Mehta, A.M. Haque, Design and Simulation of Luo Converter for DC Motor Control for an Electric Vehicle Applications, International Journal of Applied Research in Science and Engineering (2017) 57–60. [17] K. Prasanna, et al., Implementation of Positive Output Super Lift LUO Converter for Photo Voltaic System, International Research Journal of Engineering and Technology (IRJET) 2 (3) (2015) 447–452. [18] V. Sagar, et al., LUO Converter for Low-Power Applications Using A Super Capacitor, IJRAR- International Journal of Research and Analytical Reviews 5 (3) (2018) 996–1004. [19] A. Sivakumar, et al., Performance Evaluation of Conventional Controller for Positive Output Re Lift LUO Converter, International Journal of Innovative Research in Computer and Communication Engineering 2 (1) (2014) 2599–2606. [20] S. Subasri, C. Govindaraju, Design And Analysis Of LUO Converter Based Led Driver, International Journal of Electrical and Electronics Research 5 (2) (2017) 20–26. [21] R. Sujatha, M. Chilambarasan, R. Babu M, Design and Simulation of Fused LUO Converters, ARPN Journal of Engineering and Applied Sciences 10 (8) (2015) 3717–3720. [22] S. Sundaramoorthi, et al., Design and Development of an Adaptive control using Model following technique for DC-DC Boost converter, International Journal of Engineering Research & Technology (IJERT) 6 (2) (2018) 1–6. [23] A. Tekade, et al., Analysis of a Positive Output Super-Lift LUO Boost Converter, International Journal of Engineering Research and Applications 6 (2) (2016) 74–78. Sivakumar Arumugam has received the Bachelor degree in Electrical and Electronics Engineering from Anna University India in 2012. M.E,Power Electronics and Drives from Anna university in the year of 2014.He is pursuing Ph.D in Vellore Institute of Technology,Chennai, India. His Area of interest includes in the field of Renewable Energy Systems, Power Electronics Converters and Control.

References [1] V. Arikatla, J.A.A. Qahouq, An Adaptive Digital PID controller scheme for power converters, IEEE Publication, 2011. [2] M.P. Chand, G. Ramesh, Design Of New Positive Output Super-Lift LUO Converter For Solar Input In Comparison With Different DC-DC Converters, International Research Journal of Engineering and Technology (IRJET) 3 (9) (2016) 1588–1594. [3] M. Chilambarasan, et al., Design And Simulation of LUO Converter Topologies For Photovoltaic Applications, International Journal of Applied Engineering Research 9 (23) (2014) 21553–21560. [4] Circuit diagram of the conventional LUO converter, As Cited in Dhamodharan, S, (2014). An Improved LUO Converter For High Power Applications, IJRET: International Journal of Research in Engineering and Technology 03 (11) (2014) 360–365. [5] S. Dhamodharan, An Improved LUO Converter for High Power Applications, IJRET: International Journal of Research in Engineering and Technology 03 (11) (2014) 360–365.

Premalatha Logamani did her Master’s at Thiagarajar College of engineering, Madurai, India, in 1997 and acquired her Ph.D., in Electrical Engineering from Anna University, India, in the year 2009. She is currently working as a Professor in VIT University, Chennai, India. Her research interests include Power Electronics & Drives, Nonlinear dynamic systems & control, Electromagnetic compatibility and Power quality.