A Power Factor Profile-Improved EV Charging System Using Bridgeless Buckboost-Cuk Converter

Shukla, Tanmay; Prasad Patidar, Narayan; Adhikari, Apsara

doi:https://doi.org/10.1155/2023/9713102

International Transactions on Electrical Energy Systems

On this page

Abstract Introduction Conclusion Appendix Data Availability Conflicts of Interest References Copyright Related Articles

Research Article | Open Access

Volume 2023 | Article ID 9713102 | https://doi.org/10.1155/2023/9713102

A Power Factor Profile-Improved EV Charging System Using Bridgeless Buckboost-Cuk Converter

Tanmay Shukla,¹Narayan Prasad Patidar,¹and Apsara Adhikari²

Academic Editor: C. Dhanamjayulu

Received26 Apr 2023

Revised17 Jul 2023

Accepted25 Jul 2023

Published10 Aug 2023

Abstract

This article presents a power factor profile-improved bridgeless buckboost-Cuk converter-fed battery charging system for electric vehicle applications. The conventional charging system does not use any power factor improvement stage, due to which the supply current harmonics are very high and violate IEC-61000-3-2 standard guidelines. To meet the international standard guidelines, a compact and efficient power factor-improved converter stage is necessary. The power factor-improved converter in the present work uses a fourth-order Cuk converter during negative semi-cycle and a second-order buckboost converter during positive semi-cycles of the supply voltage. The amalgamation of a second- and fourth-order converter in a bridgeless configuration reduces the system’s order concerning a bridgeless Cuk converter-based system and also eradicates the need for a diode-based bridge rectifier (DbBR). Due to the presence of an input side inductor, there is no requirement for an external filter like a bridgeless buckboost converter-based scheme. The input inductor in the present scheme performs twin action; it reduces harmonic disturbances in the mains current during the negative semi-cycle and also works with capacitor C_P to filter harmonics and improve the mains current profile during the positive semi-cycle of the mains voltage. The power factor-improved converter in the present work is operated in discontinuous conduction mode (DCM). This eliminates the requirement for extra sensors compared to continuous conduction mode (CCM). The scheme also eliminates the need for two extra back-feed diodes which are generally required in bridgeless configuration loop completion during different semi-cycles of mains voltage. In the present scheme, the work of back-feed diodes is done by the anti-parallel inherent diodes of the switches. In the second stage, a high-frequency-operated flyback converter is used which not only boosts the battery current profile but also provides the electrical isolation between the supply side and load. This article also presents the detailed stability analysis and math modeling of the presented bridgeless buckboost-Cuk converter. The presented system is built on MATLAB/Simulink, and results are presented and discussed to validate the system performance.

1. Introduction

From the views of both power distributors and consumers, the charging station outfitted with an improved power factor profile is highly anticipated given the exponentially growing proportion demand for electric vehicles (EVs) [1]. The traditional EV chargers often start with a supply-mains connected DC-DC converter, accompanied by the amalgamation of a diode-based bridge rectifier (DbBR) and a DC link capacitor (C_DC). The amalgamation of DbBR and a hefty DC-link capacitor suffers a negative impact on EV charger performance, costing lower power factor at mains, high distortion factor, poor displacement factor, and lower charger efficiency since they pull distorted high-harmonics peaky current from the AC mains [2]. Single-phase (1 − ɸ) power factor profile improvement approaches are lavishly used to reduce or eliminate the previously mentioned demerits of the low-power traditional chargers. A DC-DC converter is used between DbBR and C_DC in a power factor profile improvement approach to enhance the supply-side performance of the charger from the perspective of power quality. It is important to remember that a power factor profile improvement converter can carry out various functions in a charger depending on the charger’s configuration, such as two-stage chargers or single-stage chargers. In a two-stage arrangement, a power factor profile improvement converter is used to meet supply-side needs, and a second DC-DC converter is needed to meet load-side demands, whereas in single-stage chargers, only a power factor profile improvement converter performs both functions. For battery charging applications, many two-stage charger designs based on various power factor profile improvement technologies have been investigated [3–5]. However, each method has its advantages and disadvantages in terms of switching losses and conduction losses [4], control complexity [6], device count [7], and efficiency [8]. Many bridgeless power factor profile improvement converters with complete or partial [9, 10] deletion of the DbBR have been described to improve the input side power factor and charger’s efficiency. Reference [11] provides a thorough analysis of bridgeless power factor profile improvement converters. Bridgeless charging methods have recently been suggested to lower charger losses and component count while maintaining the benefits of two-stage chargers [12, 13]. The semiconductor devices are shared by both semi-cycle converters in an integrated manner, which lowers the associated losses and overall device count. However, their reduced appeal for EV applications is due to more device stresses and increasing control complexities. One of the main benefits of a 1 − ɸ two-stage charger is the ripple-free charging current. The block diagram of the power factor profile-improved two-stage battery charger is shown in Figure 1. The charging system consists of a rectifier connected to the supply mains. The rectifier output is connected to a power factor profile improvement converter. Then, the output is again connected to an isolated converter (flyback converter in the present case) which not only takes care of the battery profile but also provides electrical isolation between output and input which adds to safety standards.

However, various research articles have asserted that low-frequency charging current ripples, when appropriately controlled, have no negative effects on the battery’s performance [14, 15]. To address the demerits of dual-stage chargers, many researchers have offered several single-stage charger topologies for EVs coupled with improved supply mains power quality to solve these shortcomings of two-stage chargers [16]. But, the single-stage chargers have their demerits which include poor performance, comparatively poor power quality, low duty cycle operation for low-power batteries, and no isolation between supply and load, giving rise to safety constraints. The limited output voltage feature of the standard boost converter and the conventional buck converter’s severe mains current distortion around the zero crossing [17] restricted output voltage exclude their potential use as a power factor profile improvement converter in EV chargers. Therefore, using buck-boost and its derived converters like the buck-boost, Zeta, CSC, SEPIC, Cuk, Luo, Landsman, and many more DC-DC converters usually eliminates the drawbacks of buck and boost converters.

The typical buck-boost converter always requires filters to remove harmonics due to the absence of input inductance. However, Cuk and SEPIC models exhibit good input and output current ripple characteristics due to the presence of inductors at both load and supply side [18]. Various other converters with high gain are presented in [19–24].

Apart from bridged converters (require DbBR), two popular arrangements exist. One is a parallel arrangement also called interleaved arrangement [25, 26] and the other is a bridgeless arrangement [27]. The interleaved arrangement provides parallel paths which allow current division resulting in lower current stress across elements of the converter. However, in a bridgeless arrangement, two different converters operate during two semi-cycles of supply voltage. Various power factor-improved converter-based chargers are presented in [22, 25–28]. In this paper, a two-stage 1 − ɸ charger with a bridgeless buckboost-Cuk power factor profile improvement converter at an initial stage and a flyback converter at a later stage is presented. The charger also offers electrical separation between the supply side and load as an isolated flyback converter is employed in the later stage to boost the load current profile. The gate pulse for the two stages is generated using a simple voltage and current tracker methodology. The complete charging system using a bridgeless buckboost-Cuk AC-DC converter for power factor profile improvement is shown in Figure 2. The following are the article’s notable contributions:(1)Primary stage bridgeless buckboost-Cuk power factor profile improvement converter uses ingrained anti-parallel IGBT diodes for back feeding during supply voltage’s negative (−ve) semi-cycle and positive (+ve) semi-cycle. So, no separate additional diodes are needed for loop-completing purposes during supply voltage’s both semi-cycles. However, back-feeding diodes are usual demands for bridgeless schemes.(2)The power factor profile-improved bridgeless buckboost-Cuk converter utilizes a Cuk converter of order four with a buck-boost second-order converter for supply voltage’s negative and positive semi-cycles, respectively. The amalgamation of second-order buck-boost with input inductor blessed fourth order Cuk converter results in lessening of net order of power factor profile improved bridgeless buckboost-Cuk converter concerning filter cascaded two order bridgeless converter and fourth order bridgeless converter.(3)The supply side inductance of the fourth-order negative semi-cycle Cuk converter lessens the harmonic disturbances in the mains current and also participates as a filter component for a positive semi-cycle buck-boost converter. So, the need for extra filtering inductance is eradicated in this scheme.(4)Inductance in the output loop of the converter operation boosts the load current profile.(5)The converter switches’ gate pulses are produced in the current work using a straightforward voltage tracking control system, and both switches are fed with the identical gate pulse.(6)The DCM operation lessens the inductor size and also reduces the required sensor count.

The presented DCM-operated bridgeless buckboost-Cuk converter works as an inbuilt power factor profile improver to get a linear straight-line relation between mains voltage and current. However, the later-stage flyback converter is used to boost the load current profile with electrical isolation between the supply and load side.

2. Bridgeless Buckboost-Cuk Power Factor Improvement Converter Configuration

The bridgeless buckboost-Cuk power factor improvement converter used in battery chargers with reduced component count is shown in Figure 3. The presented power factor improvement converter works as a Cuk converter for negative semi-cycle, whereas it works as a buck-boost converter for positive semi-cycle interval. The built-in advantage of employing a Cuk converter is its incorporation of input terminal inductance, which transforms the voltage supply as a current source, thereby changing the converter from being fed by voltage to being fed by current. The current-fed converter performs better than the voltage-fed converter in comparison, and the input terminal inductance also functions as filter element alongside capacitor C_P for positive semi-cycle buck-boost converters. The strategy suggested makes use of the IGBT’s anti-parallel inherent diodes for circuit-completing purposes during both semi-cycles of the supply voltage. However, bridgeless configurations use two different diodes typically, one for each input voltage semi-cycle, to complete the loop.

2.1. Operation of Power Factor Improvement Bridgeless Buckboost-Cuk Converter

In the proceeding section, a bridgeless buckboost-Cuk converter under DCM operation has been described. For the bridgeless buckboost-Cuk converter under DCM, a total of six cases exist—three during the negative semi-cycle and the remaining three for the positive semi-cycle of the mains voltage. To have more clarity on the bridgeless buckboost-Cuk converter operation and absence of symmetry in power factor improvement bridgeless buckboost-Cuk converter, both semi-cycle operations are explained in the proceeding section. The conduction loop of the power factor improvement bridgeless buckboost-Cuk converter during different possible cases is depicted in Figures 4(a)–4(f).

(a)

(b)

(c)

(d)

(e)

(f)

DCM bridgeless buckboost-Cuk converter’s operation during different possible cases is as follows.(i)Positive semi-cycle of supply voltage:(1)IGBT switch S_P is on.(2)IGBT switch S_P is turned off.(3)IGBT switch S_P is off and also inductor L_P current vanishes (DCM of positive semi-cycle).(ii)Negative semi-cycle of supply voltage:(1)IGBT switch S_N is on (gate pulse applied).(2)IGBT switch S_N is turned off (not conducting).(3)IGBT switch S_N is off and also diode D_N stops conducting (DCM of negative semi-cycle).

The bridgeless buckboost-Cuk power factor improvement converter working during different DCM operations is explicated as follows.(1)Mode-I: The start of a positive semi-cycle of the supply voltage is ushered in. During this interval, IGBT S_P is fed with a gate pulse. The conduction loops for this mode are C_P-L_N1-V_IN-C_P and C_P-L_P-S_P-C_P. During mode-I, the inbuilt anti-parallel IGBT (S_N) diode conducts to form the loop. The mode-I conduction path is shown in Figure 4(a). The equation provided below serves to calculate inductor current [27]. When operating in mode-I, the peak current value flowing through an IGBT SP can be calculated as where T_S symbolizes the single cycle interval and d₁ represents the duty.(2)Mode-II: In mode-II, IGBT S_P is withdrawn with gate pulse. Mode-II conduction loops are depicted in Figure 4(b). During mode-V, the inductor L_P discharges through diode D_P and load. The diode current can be evaluated by using the following formula.(3)Mode-III: DCM of positive semi-cycle is the last mode of the positive semi-cycle. Mode-III conduction loops are shown in Figure 4(c). Mode-VI starts when the inductor’s energy storage runs out.(4)Mode-IV: During mode-IV, IGBT S_N is given with gate pulse. The conduction path of mode-IV is V_IN-L_N-C_P-V_IN and S_N-C₀||R-L_N2-C_N-S_N. During this working mode, capacitor C_N is discharged through a load. The loops during mode-IV are shown in Figure 4(d) for more clarity. The max value of IGBT S_N current stress during mode-IV can be found as [27] where(5)Mode-V: In mode-V, switch S_N is turned off, and this mode’s conduction loop is shown in Figure 4(e). Capacitor C_N charging occurs during mode-V, and this time period also observes the diode’s D_N conduction. L_N1-C_N-D_N-C_P-V_IN-L_N1 is a loop during mode-V. Another loop is made of inductor L_N2, diode D_N, and DC-link capacitor (C₀) in parallel with the load. Using the equation, the maximum diode current via diode D_N may be determined. where . The peak voltage across switch SN is determined as follows:(6)Mode-VI: IGBT S_N is still non-conducting during this mode. This mode starts at the instant when diode D_N stops conducting; as a result, same current flows through capacitor C_N and inductor L_N2. Mode-VI can also be called DCM during the negative semi-cycle of the supply voltage. The conducting path during mode-VI is shown in Figure 4(f).

The DCM mathematical equation can be written as [27]where .

The characteristic waveform for positive and negative semi-cycle converter is shown in Figures 5(a) and 5(b).

(a)

(b)

2.2. Distinctive Features of Bridgeless Buckboost-Cuk Power Factor Improvement Converter

The distinctive features of the bridgeless buckboost-Cuk power factor improvement converter are power factor profile improvement, lesser component count, efficiency enhancement, simpler control, DbBR elimination, reverse feeding diode removal, and output inductance (L_N2 and L_P) availability to increase the load current pattern during the positive (+ve) and negative (−ve) mains voltage semi-cycles. Table 1 lists the number of switches, capacitors, diodes, inductors, and transformers used in the charger along with total element count across various topologies comparing several bridgeless (BL) converter-based two-stage charging systems without taking battery into account.

2.3. Flyback Load Profile Improvement Converter Operation

The flyback load profile improvement converter operates in two modes, first is when IGBT S_fb is on and the other is when IGBT S_fb is off. During the first mode, the transformer’s primary winding charges, but due to dot conventions and reverse connected diode in the flyback converter, the secondary current cannot flow through the load. During S_fb on mode, the current through IGBT S_fb is given as [27]where I_{L_fb} (0) is magnetizing current through the inductance just before IGBT S_fb is on. The switching period of the flyback converter is taken as 50000⁻¹ s in ongoing work, so the frequency of the flyback converter is 50 kHz. Transformation ratio (N₂/N₁) is taken as 1 : 3. The peak voltage across the diode can also be estimated as [27]where V_b symbolizes battery voltage. The second mode of operation begins the instant when IGBT S_fb is turned off. Due to reverse dot conventions, the diode, d_fb befits forward-biased and power is delivered to the battery in this mode. The magnetizing inductance’s current is described as [27]where I_{L_fb} (0) is the initial current through magnetizing inductor during the start of this mode. The peak voltage across the flyback S_fb is given as [28, 29, 31]

2.4. Selection of Bridgeless Buckboost-Cuk Power Factor Improvement Converter Components

The bridgeless buckboost-Cuk converter’s DCM functioning begins with the total disappearance of diode current (I_DN) during the supply voltage’s negative semi-cycle. In this case, the inductor L_N2 current crosses zero value and becomes positive with its magnitude equal to the capacitor C_N current. However, positive semi-cycle DCM operation begins upon inductor’s (L_P) full current discharge. For DCM functioning, the inductor L_P value must be chosen so that the inductor discharges completely before the supply voltage’s positive semi-cycle is finished. However, the capacitor voltages V_CN and V_CP remain regular throughout the interval. A 48 V, 850 W battery (charger and motor specification in Appendix) is utilized in the current article to verify the charger. The average mains voltage to the charger can be written as [27, 29]

The bridgeless buckboost-Cuk converter’s transfer function over both semi-cycles can be determined by applying the V-sec (voltage-second) balancing across its inductors [27].

The value of duty ratio of the power factor-improved converter seems to be depending on the average input mains voltage and the voltage across the DC-link capacitor [27–29].

For DCM operation, the value of inductance L_N1 and switching frequency must be chosen carefully. For choosing switch losses and inductor size, switching frequency and inductance values are crucial factors. The size and magnitude of the inductor grow as the switching frequency lowers. High switching frequencies cause the solid-state device (switch) to experience more switching losses, necessitating the use of a heat sink with an extensive surface area. In addition, a bridgeless buckboost-Cuk converter operating in DCM has an issue with increased current stress caused by a decreased level of inductance. Although switching losses are significantly reduced with a lower switching frequency, the cost, size, and magnitude of the inductor all go up. Therefore, keeping the aforementioned factors in mind, 20 kHz is chosen as the switching frequency for the current job. For the bridgeless buckboost-Cuk converter, the following relation is used to determine the critical value of input inductance, L_N1 [27, 29–31].

The value picked ought to be higher than the determined critical level since the input inductor must function in CCM. The L_N1 value selected for the current work is 4.5 mH. Utilizing the following formula, the output inductance values L_N2 and L_P may be determined [29–31].

The output inductor changes its current polarity, so it must be operated in DCM for discontinuous working of the bridgeless buckboost-Cuk converter. Therefore, a magnitude equal to 0.195 mH, or 20^th part of the evaluated value, is selected for this study. The following formula can be used to determine the value of capacitor C_N [29–31]:

The value chosen for capacitor C_N must be higher than the computed critical value in order for it to function in CCM. Therefore, C_N is set to be 0.5 F for the purpose of this investigation. The formula that can be used to determine the filter capacitor’s value for a converter running in a positive semi-cycle of the mains voltage is [27–31]

In order to calculate filter capacitance, the cutoff frequency ought to fall between switching and line frequencies, and hence for the current task, a cutoff frequency of 4 kHz was decided upon. By rearranging the power equation, it is possible to calculate the value of the DC-link capacitor (C₀) [27–32].

A DC-link capacitor handles the second harmonic portion, so equations are [27–32]where represents the permitted voltage variation across the DC link. Equation (23) can be used to compute the value of the DC link capacitance C₀ [27–31].

Therefore, a 1.8 mF capacitor is selected for the DC-link. Less switching (line) frequency is required when using the capacitor because of the influence of second-order harmonics. In terms of comparison, the capacitor needs to have a larger current rating and a higher capacitance value. So, the capacitor selected must have a larger capacitance for unit volume, and electrolytic capacitors might be appropriate for this application.

2.5. Selection of Flyback Load Profile Improvement Converter Components

The flyback converter needs to control the output value at 60 volts for which the coupled inductor transformation ratio is taken to be 1 : 3 which guarantees the stepping down of voltage from 300 V to battery voltage. The duty cycle for the flyback converter comes out to be [29–31]

The magnetizing inductance can be calculated using the following relation [29–31].

The magnetizing inductance for this work is taken to be 30 μH. The calculation of battery capacitance (i.e., C_b) is done as follows [29–31].where is the permissible ripple in output battery voltage which is taken to be 0.01% for the present article. The flyback converter capacitor (C_b) is chosen to be equal to 2 mF.

3. Bridgeless Buckboost-Cuk Power Factor Profile Improvement Converter-Based Charger Control

The control scheme for the charger powered by the bridgeless buckboost-Cuk AC-DC converter is described in this section. The complete charger system uses two different control loops, one for the flyback load profile enhancement converter and the other for the bridgeless buckboost-Cuk converter.

3.1. Bridgeless Buckboost-Cuk Power Factor Profile Improvement Converter Control Scheme

In the current work, DCM operation employing a bridgeless buckboost-Cuk converter for power factor profile improvement is accomplished using a voltage-tracking approach. This control needs sensed DC-link voltage which requires one voltage sensor, unlike CCM which requires two voltage sensors and one current sensor. The formal representation of the control system for the DC-link voltage is shown in Figure 6. The error generator, pulse-width modulation (PWM) generator block, proportional-integral (P-I) controller, and sawtooth wave generator are used in this control method.

The error generator is supplied with reference DC-link voltage and the actual (sensed) DC-link voltage. At the q^th sample instant, the error signal or error generator’s output can be expressed as follows [29–31].

To extract a constant output voltage (V₀), P-I controller is supplied with the error signal. The controller’s output voltage, V_Cn, can be represented as [29–31]where the integral gain (K_I) and proportional gain (K_P) are tuned P-I controller’s parameters. When controlled voltage (V_Cn) is sent through a relational operator and compared to a high-frequency sawtooth wave (Y_S), the result is a gate signal for the switches S_N and S_P. The following describes how relational operators employ logic [27]. For V_IN > 0 If Y_S ≤ V_Cn implies IGBT S_P is on If Y_S > V_Cn implies IGBT S_P is “SWITCHED OFF” For V_IN < 0 If Y_S ≤ V_Cn implies switch S_N is on If Y_S > V_Cn implies IGBT S_N is “SWITCHED OFF.”

3.2. Control of Flyback Load Profile Improvement Converter

The control of a flyback load profile improvement converter consists of two-loop P-I controllers. The control scheme requires two sensors: one for sensing battery voltage and the other for sensing battery current. The sensed battery voltage is compared with the reference battery voltage, and the battery voltage error V_b,er is fed to the voltage P-I (V-P-I) controller. This block acts as a controller during constant voltage mode; otherwise, it only acts as a saturation block. The controlled output (C_Vb) from the V-P-I controller with P and I tuned parameters K_V,P, and K_V,I, respectively, can be written as [29–31]

During constant current (C-C) battery charging mode, another current P-I (C-P-I) block comes into action. During C-C mode, the V-P-I controller output gives the rated current as the battery current during C-C mode is intentionally made equal to the rated battery current value. The rated current and sensed current are applied to the subtraction block which provides error (I_b,er). The current error signal is fed to C-P-I controller to generate a duty cycle (C_Ib). The sawtooth wave of high frequency (50 kHz in this work) is compared with the duty to get the flyback switch gate pulse. The useful equations for C-C battery charging mode with C-P-I controller tuning parameters K_I,P and K_I,I are as follows [29–31].

4. Small-Signal Analysis and State-Space Model (SSM) of Bridgeless Buckboost-Cuk Converter

By utilizing the fundamentals of network theory, the bridgeless buckboost-Cuk power factor profile improvement converter conduction loops during each operating mode can be rewritten into first-order differential equations (FoDEs), which could be used to explain the device dynamics. These FoDEs are expressed in traditional state-space form for stability analysis purposes [20, 27]. The common equations for the state-space model are as follows [27].where T equals t1, t2, t3 for the mains voltage’s negative semi-cycle and , , for the mains voltage’s positive semi-cycle. This work studies the stability of negative as well as positive semi-cycle converter using the pole-zero projection and Bode plot. A stability test for the bridgeless buckboost-Cuk converter is displayed in Figure 3.

4.1. Stability Analysis of Converter Operating in Positive Semi-Cycle of Supply Voltage

The positive semi-cycle converter’s S-S matrix vectors are as follows.where R represents the load to the bridgeless buckboost-Cuk converter which can be calculated by using the following relation.

When using a positive semi-cycle bridgeless buckboost-Cuk converter in DCM, the state-space (S-S) matrix that needs to be included in the standard S-S equation can be expressed as [27]

Now, by using equations (34)–(36), the transfer function for the positive semi-cycle converter can be expressed as

Additionally, Figures 7(a) and 7(b) show the pole-zero map and the Bode diagram, respectively, for the positive cycle converter, along with the transfer function of the P-I controller as stated in equation (37). The gain and phase margins of the positive semi-cycle converter are 42 dB and 90.3°, respectively, demonstrating good stability.

(a)

(b)

4.2. Stability Analysis of Bridgeless Buckboost-Cuk Converter Operation during Supply Voltage’s Negative Semi-Cycle

The matrix components for the mains voltage’s negative semi-cycle are shown below:where .

When using a negative semi-cycle bridgeless buckboost-Cuk converter in DCM, the state-space (S-S) matrix that needs to be included in the standard S-S equation is

Now, the bridgeless buckboost-Cuk converter’s transfer function (TF) for a negative semi-cycle is

With the application of component value in desired unit of the bridgeless buckboost-Cuk converter used in DCM operation, the transfer function can be estimated. TF for negative semi-cycle bridgeless buckboost-Cuk power factor profile improvement converter is given by

The pole-zero (P-Z) map of TF_{BL-Buckboost-Cuk,(−ve)}, shown in Figure 8(a), also shows five poles (depicted by a cross inside circle). None of the five poles can be seen on the left portion of the x-y plane divided by Y axis in the P-Z map which confirms bridgeless buckboost-Cuk power factor profile improvement converter’s stability during the negative semi-cycle. The transfer function (TF) of the P-I controller, which is cascaded with the converter for closed-loop operation, is stated below [27].where K_CP and K_CI are tuned proportional and integral constants. The tuned values of both K_CI and K_CP are chosen at 0.022 and 0.0018, respectively, found by the trial and error method. Figure 8(b) depicts the Bode plot of the power factor profile improvement system (bridgeless buckboost-Cuk converter and control) using the bridgeless buckboost-Cuk converter’s negative cycle transfer function and TF_C (b). Large and non-negative values of phase (50.3°) and gain (91.7 dB) margins demonstrate good stability of the negative semi-cycle converter.

(a)

(b)

5. Validation and Result

In this part, MATLAB/Simulink results are used to analyse the performance of the bridgeless buckboost-Cuk power factor profile enhancement converter-based charger under steady-state and dynamic situations.

5.1. Steady-State Performance of Charger

Steady-state bridgeless buckboost-Cuk power factor profile improvement converter-based charger is discussed in this section. Figures 9(a)–9(e) represent mains voltage, mains current, battery voltage (V_b), battery current (I_b), and state of charge (SOC), respectively, with mains voltage of 220 V and 300 V DC-link voltage with battery voltage equal to 48 V. Figures 9(a) and 9(b) show the mains current and voltage following a straight line (linear) relationship, and the battery profile is shown in Figures 9(c)–9(e).

(a)

(b)

(c)

(d)

(e)

5.2. Performance of Bridgeless Buckboost-Cuk Power Factor Profile Improvement Converter

The effectiveness of the bridgeless buckboost-Cuk converter is covered in this section. The voltage across the filter capacitor C_P and intermediary capacitor C_N is depicted in Figures 10(a) and 10(b). The capacitor C_N’s maximum voltage was discovered to be 777 V, while the capacitor C_P’s maximum voltage came out to be 576 V. Figures 10(c)–10(e) display the inductor currents L_P, L_N1,, and L_N2, respectively. The current across two converter switches (i.e., I_SP and I_SN) is displayed in Figures 11(a) and 11(b). This further records the conduction of IGBT switches’ body diodes. Figures 11(c) and 11(d) show the current flowing through the two diodes (D_P and D_N), which illustrate the diode current’s discontinuous function.

(a)

(b)

(c)

(d)

(e)

(a)

(b)

(c)

(d)

5.3. Bridgeless Buckboost-Cuk Converter-Based Charger Dynamic Performance

The dynamic functionality of the displayed charger is covered in this section. Figure 12 illustrates how the bridgeless buckboost-Cuk power factor profile-improved converter-based charger is affected by varying the supply voltage. When the mains voltage shifts from 220 V to 150 V at moment t = 0.38 sec, Figure 12 clearly depicts an increase in mains current, whereas a drop in mains current occurs when the supply voltage is restored back to 220 V at instant t = 0.98 sec. Figures 12(c)–12(e) show no significant interruption in battery charging with a sudden change in supply voltage.

5.4. Efficiency Comparison

The efficiency of the presented converter can be calculated by using the following formula.

The presented charger efficiency at different input power is drawn and its comparison with PFI Cuk with DbBR fed charger [22], PFI BL-Cuk fed charger [22], PFI buck-boost with DbBR and filter-based charger, and PFI BL-buck-boost with filter-based charger has been discussed in this section. The PFI Cuk converter with DbBR fed charger and PFI buck-boost with DbBR fed charger use DbBR for AC-DC conversion, and the maximum efficiency of the diode bridge rectifier is 81.2%, which can be calculated by using the following formula.

The DbBR not only harnesses the system with conduction losses but it has switching losses too. The elimination of DbBR improves the efficiency of the remaining three systems. The use of an input side filter includes two energy storage elements that curse the system with additional conduction losses. The presented charger’s efficiency is approximately 92% which is higher than the efficiency of other mentioned chargers because the presented charger neither requires a filter nor it uses DbBR and also has lesser component count than the PFI BL-Cuk converter-based charger due to sandwiching of second-order and fourth-order converter in BL configuration. The efficiency vs. input power graph of the abovementioned systems is shown in Figure 13.

6. Conclusion

This study discusses the detailed mathematics and stability analysis of the bridgeless buckboost-Cuk converter employed in EV chargers. Bridgeless buckboost-Cuk power factor profile improvement converter’s stability has been investigated by Bode diagram and pole-zero maps. The simulation result analysis from the MATLAB platform Simulink model of the charging system has been taken into account and researched in the study. The performance of a proposed bridgeless buckboost-Cuk converter with enhanced power quality, smaller component count, and higher efficiency has been validated using Simulink findings from the MATLAB platform. The presented bridgeless buckboost-Cuk converter-based charger comes with various benefits, including size reduction and easy control. The total distortion in mains current is seen to be 1.9% at 220 V RMS supply voltage under steady-state conditions. The dynamic state results also seem to reflect satisfactory performance. Thus, the overall performance of the charger has been validated using the result data.

Appendix

Rated speed = 0–28 Km/h. Battery ratings: 124 V, 100 Ah. Charger specifications: input supply = 170–250, output current = 10-11 A, and open circuit voltage = 55–58 V. Motor specifications: 48 V, 850 W BLDC motor.

Data Availability

The data used to support the findings of this study are not publicly available because the authors do not want to share.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

References

NITI Aayog and WEC, Zero-Emission Vehicles: Towards A Policy Framework, NITI Aayog, New Delhi, India, 2008.
Z. Yang and P. C. Sen, “Recent developments in high power factor switch-mode converters,” in Proceedings of the IEEE Canadian Conference on Electrical and Computer Engineering (CCECE), vol. 2, pp. 477–480, Waterloo, Canada, December 1998.
View at: Google Scholar
H. Wang, S. Dusmez, and A. Khaligh, “A novel approach to design EV battery chargers using SEPIC PFC stage and optimal operating point tracking technique for LLC converter,” in Proceedings of the Annual IEEE Conference on Applied Power Electronics Conference and Exposition (APEC), pp. 1683–1689, Fort Worth, TX, USA, January 2014.
View at: Google Scholar
S. Ryu, D. Kim, M. Kim, J. Kim, and B. Lee, “Adjustable frequency–dutycycle hybrid control strategy for full-bridge series resonant converters in electric vehicle chargers,” IEEE Transactions on Industrial Electronics, vol. 61, no. 10, pp. 5354–5362, 2014.
View at: Publisher Site | Google Scholar
S. Thangavel, D. Mohanraj, T. Girijaprasanna, S. Raju, C. Dhanamjayulu, and S. M. Muyeen, “A comprehensive review on electric vehicle: battery management system, charging station, traction motors,” IEEE Access, vol. 11, pp. 20994–21019, 2023.
View at: Publisher Site | Google Scholar
D. Kim and B. Lee, “Asymmetric control algorithm for increasing efficiency of nonisolated on-board battery chargers with a single controller,” IEEE Transactions on Vehicular Technology, vol. 66, no. 8, pp. 6693–6706, 2017.
View at: Publisher Site | Google Scholar
A. V. J. S. Praneeth and S. S. Williamson, “A wide input and output voltage range battery charger using buck-boost power factor correction converter,” in Proceedings of the Annual IEEE Conference on Applied Power Electronics Conference and Exposition (APEC), pp. 2974–2979, Anaheim, CA, USA, March 2019.
View at: Google Scholar
A. M. Elrajoubi, S. S. Ang, and K. George, “Design and analysis of a new GAN-Based ac/dc converter for battery charging application,” IEEE Transactions on Industry Applications, vol. 55, no. 4, pp. 4044–4052, 2019.
View at: Publisher Site | Google Scholar
A. Dixit, K. Pande, S. Gangavarapu, and A. K. Rathore, “DCM-based bridgeless PFC converter for EV charging application,” IEEE Journal of Emerging and Selected Topics in Industrial Electronics, vol. 1, no. 1, pp. 57–66, 2020.
View at: Publisher Site | Google Scholar
H. Yang, H. Chiang, and C. Chen, “Implementation of bridgeless Cuk power factor corrector with positive output voltage,” IEEE Transactions on Industry Applications, vol. 51, no. 4, pp. 3325–3333, 2015.
View at: Publisher Site | Google Scholar
Z. Chen, P. Davari, and H. Wang, “Single-phase bridgeless PFC topology derivation and performance benchmarking,” IEEE Transactions on Power Electronics, vol. 35, no. 9, pp. 9238–9250, 2020.
View at: Publisher Site | Google Scholar
M. Wang, S. Pan, J. Gong, W. Lin, Y. Li, and X. Zha, “High-efficiency high-power bridgeless integrated AC-DC converter for on-board vehicle battery charger,” in Proceedings of the Annual IEEE Conference on Applied Power Electronics Conference and Exposition (APEC), pp. 1997–2003, New Orleans, LA, USA, September 2020.
View at: Google Scholar
I. Askarian, N. Dohmeier, C. Botting, M. Pahlevani, and A. Knight, “A new control method for a novel isolated, bridgeless single-stage AC/DC converter used in industrial battery chargers,” in Proceedings of the Annual IEEE Conference on Applied Power Electronics Conference and Exposition (APEC), pp. 763–767, Anaheim, CA, USA, August 2019.
View at: Google Scholar
T. Kim, “Analytical study on low-frequency ripple effect of battery charging,” in Proceedings of the Annual IEEE Conference on Applied Power Electronics Conference and Exposition (APEC), pp. 809–811, Seoul, South Korea, February 2012.
View at: Google Scholar
L. Chen, S. Wu, D. Shieh, and T. Chen, “Sinusoidal-ripple-current charging strategy and optimal charging frequency study for Li-ion batteries,” IEEE Transactions on Industrial Electronics, vol. 60, no. 1, pp. 88–97, 2013.
View at: Publisher Site | Google Scholar
S. Jeong, W. Cha, S. Lee, J. Kwon, and B. Kwon, “Electrolytic capacitorless single-power-conversion on-board charger with high efficiency,” IEEE Transactions on Industrial Electronics, vol. 63, no. 12, pp. 7488–7497, 2016.
View at: Publisher Site | Google Scholar
H. Ma, Y. Li, J. Lai, C. Zheng, and J. Xu, “An improved bridgeless SEPIC converter without circulating losses and input-voltage sensing,” IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 6, no. 3, pp. 1447–1455, 2018.
View at: Publisher Site | Google Scholar
B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, “A review of single-phase improved power quality ac∼dc converters,” IEEE Transactions on Industrial Electronics, vol. 50, no. 5, pp. 962–981, 2003.
View at: Publisher Site | Google Scholar
M. Zaid, S. Khan, M. D. Siddique et al., “A transformerless high gain dc–dc boost converter with reduced voltage stress,” International Transactions on Electrical Energy Systems, vol. 31, no. 5, 2021.
View at: Publisher Site | Google Scholar
T. Shukla and S. Nikolovski, “A bridgeless cuk-BB converter based BLDCM drive for MEV applications,” Energies, vol. 16, no. 9, p. 3747, 2023.
View at: Publisher Site | Google Scholar
S. Khan, M. Zaid, M. D. Siddique, and A. Iqbal, “Ultra high gain step up DC/DCconverter based on switched inductor and improved voltage lift technique for high-voltage applications,” IET Power Electronics, vol. 15, no. 10, pp. 932–952, 2022.
View at: Publisher Site | Google Scholar
S. Khan, M. Zaid, M. M. A. Khan, and A. Sarwar, “A non-pulsating input current step-up DC/DC converter with common ground structure for photovoltaic applications,” IEEE Access, vol. 9, pp. 159432–159446, 2021.
View at: Publisher Site | Google Scholar
S. Khan, A. Mahmood, M. Tariq, M. Zaid, I. Khan, and S. Rahman, “Improved dual switch non-isolated high gain boost converter for dc microgrid application,” in Proceedings of the 2021 IEEE Texas Power and Energy Conference (TPEC), pp. 1–6, College Station, TX, USA, April 2021.
View at: Publisher Site | Google Scholar
S. Khan, A. Mahmood, M. Zaid et al., “A high step-up DC-DC converter based on the voltage lift technique for renewable energy applications,” Sustainability, vol. 13, no. 19, Article ID 11059, 2021.
View at: Publisher Site | Google Scholar
T. Saravanakumar and R. Saravana kumar, “Fuzzy based interleaved step-up converter for electric vehicle,” Intelligent Automation and Soft Computing, vol. 35, no. 1, pp. 1103–1118, 2023.
View at: Publisher Site | Google Scholar
T. Saravanakumar and R. Saravana kumar, “Design, validation, and economic behavior of a three-phase interleaved step-up DC–DC converter for electric vehicle application,” Frontiers in Energy Research, vol. 10, 2022.
View at: Publisher Site | Google Scholar
T. Shukla and U. K. Kalla, “A BL-CC converter-based BLDC motor drive for marine electric vehicle applications,” International Transactions on Electrical Energy Systems, vol. 2022, Article ID 7026462, 18 pages, 2022.
View at: Publisher Site | Google Scholar
R. Kushwaha and B. Singh, “Power factor improvement in modified bridgeless landsman converter fed EV battery charger,” IEEE Transactions on Vehicular Technology, vol. 68, no. 4, pp. 3325–3336, 2019.
View at: Publisher Site | Google Scholar
R. Kushwaha and B. Singh, “A power quality improved EV charger with bridgeless Cuk converter,” IEEE Transactions on Industry Applications, vol. 55, no. 5, pp. 5190–5203, 2019.
View at: Publisher Site | Google Scholar
R. Kushwaha and B. Singh, “An improved PFC bridgeless SEPIC converter for electric vehicle charger,” in Proceedings of the 2020 IEEE International Conference on Power Electronics, Smart Grid and Renewable Energy (PESGRE2020), pp. 1–6, Cochin, India, January 2020.
View at: Google Scholar
R. Kushwaha and B. Singh, “Design and development of modified BL Luo converter for PQ improvement in EV charger,” IEEE Transactions on Industry Applications, vol. 56, no. 4, pp. 3976–3984, 2020.
View at: Google Scholar
J. Gupta, R. Kushwaha, and B. Singh, “Improved power quality charger based on bridgeless canonical switching cell converter for a light electric vehicle,” in Proceedings of the IEEE 9th Power India International Conference (PIICON), pp. 1–6, Sonepat, India, February 2020.
View at: Google Scholar

Copyright

Copyright © 2023 Tanmay Shukla et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies