Enhanced Model of Hybrid Controller for Smooth Switching of Energy

Sources Used in Electric Vehicle Application

VENKATA KOTESWARA RAO N1, RAJA SATHISH KUMAR2,*,

Y. V. BALARAMA KRISHNA RAO3

1Department of Electrical and Electronics Engineering,

Stann's college of engineering and technology, Chirala,

Andhra Pradesh- 523187,

INDIA

2Department of Electrical and Electronics Engineering,

Keshav Memorial Institute of Technology,

Hyderabad,

INDIA

3Department of Electrical and Electronics Engineering,

Guru Nanak Institutions Technical Campus, Ibrahimpatnam,

Telangana-501506,

INDIA

Abstract: - The sharing of load current to battery and ultracapacitor (UC) of the multiple energy storage

structure (MESS) according to the vehicle dynamics is the main obstacle in the electric vehicles (EVs)

application. In this paper, a control strategy technique is projected, to split the current between two sources

based on the EVs requirement. A conventional/intelligent controller is used here to produce pulses to the DC-

DC converter's corresponding load on the motor. A math condition-based controller (CBC) is designed by

considering four individual math functions based on the speed condition of the motor, which is used to produce

regulated pulse signals of the switches present in converters. The combination of CBC plus

conventional/intelligent controllers makes a new hybrid controller, to achieve the main objective of the

proposed work. The performance of the designed control strategy is investigated with four modes based on

changed loads. Two different hybrid controllers CBC plus fuzzy logic (FLC) and CBC with proportional

integral derivative (PID), and implemented and a comparative analysis was also made based on different time

domain specifications by taking the speed curve as a reference.

Key-Words: - Control strategy, electric vehicles, DC-DC converters, Time-domain specifications, condition-

based controller (CBC), Proportional integral derivative (PID), Fuzzy logic (FLC) Controller.

Received: August 7, 2023. Revised: February 5, 2024. Accepted: March 1, 2024. Published: April 1, 2024.

1 Introduction

To achieve the proper energy sharing from energy

sources of MESS a single variable rate limit

function is adopted and based on that function rate

limit controller is modeled. With the modeled

control mechanism, the life of the key source is

improved by transferring the sudden power needed

of the load to the auxiliary source. According to the

designed controller function, the primary source can

serve the load during normal road conditions only

which indicates that the secondary source provides

support to the primary source, especially during

abnormal load changes and staring of the vehicle,

[1], [2].

The optimized fuel economy and driving range

are the most effective factor of EVs during the

section of the fuel to drive them. Generally, the

battery/fuel cell will act as a base source that will

not send the mandatory power to the load at all

times. Suppose the driving range of the vehicle is

improved to 15%, which will affect the cost of the

vehicle means the size of the source increases. To

overcome that problem, MESS is constructed with

UC and battery/fuel cell, [3], [4], [5].

WSEAS TRANSACTIONS on CIRCUITS and SYSTEMS

DOI: 10.37394/23201.2024.23.2

Venkata Koteswara Rao N, Raja Sathish Kumar,

Y. V. Balarama Krishna Rao

E-ISSN: 2224-266X

14

Volume 23, 2024

An NMPC (nonlinear model predictive control)

is introduced for the MESS to share the energy

between the battery and UC in an optimizing way.

The intended technique is a real-time controller,

which will improve the dynamics of the overall

system, [6], [7], [8].

To obtain the optimal current sharing between

the battery and UC two different controllers are

modeled and implemented in the system. An

improved problem is attained from the first

controller based on the Karush–Kuhn– Tucker

conditions, this will enhance the MESS efficiency

by providing the energy to the load depending upon

the applied load to the vehicle. And the second

controller is formulated based on the neural

networks which additionally have an intelligent

working future. The state of health (SoH) of the

battery has been measured for both the controllers'

working times to know the optimal performance of

the individual controller. To compare the software-

based results, and hardware model has realized.

Thereafter a comparative study was done based on

Simulink as well as hardware model results for

better validation, [9], [10], [11].

A novel MESS is anticipated with two unique

character power sources and the energy flow from

the sources to load is also controlled with a specific

controller. The proposed controller, mainly

concentrates on reducing the sudden surge effects

on the primary source by diverting to the supporting

source. The main converter BDC is used for two

ways of current flow with two separate switches for

boost and buck operations, [12], [13]. The MESS

includes two sources which are battery and UC are

connected to the DC bus through converters, to

reduce the hardware realization cost. The complete

performance of the controller used in this work is

examined based on several road conditions. The

converters used in this worked effectively for the

given power ranges of the load, [14], [15], [16].

Novel MESS is proposed and compared with

the existingexisting traditional power storage

system. In the selected UC and battery is rated with

lower voltages than the bus voltage which reduces

the fabrication cost of the overall system. With this

arrangement, the normal voltage profile has been

developed to the main source battery, by diverting

the heavy power development to the UC, [17], [18],

[19], [20].

2 Battey-Ultracapacitor Hybrid

System Architecture

Figure 1 shows its main concentration on, how to

produce the regulated signals to a converter. This

includes two converters both are used here to realize

the planned control scheme. Of those controllers

first, one is the regular one, which is used to

generate the switching, signals on the other hand

CBC controller, is capable of controlling the pulses

made by the conventional controller related to the

four math functions ON and OFF states. Here the

CBC controller takes input as speed from the

electric motor and develops the four math functions

as an output related to the speed of the motor.

Fig. 1: Representation of the main circuit with all

necessary components

Fig. 2: Main circuit with BDC and UDC including

switches

In this circuit, MESS is showing which is

comprised of battery and UC which clear in Figure

2. The BDC can operate under boost as well as buck

modes. Generally, BDC will act as a medium

between load to source and the power flow may be a

load to source or source to load related to the

applied torque to the motor. On the other hand,

UDC also acts as between battery to load and which

allows power flow from source to load only. In this

work point of view, switches S1, S2, and S3 are

corresponding to UDC and BDC. Except during

WSEAS TRANSACTIONS on CIRCUITS and SYSTEMS

DOI: 10.37394/23201.2024.23.2

Venkata Koteswara Rao N, Raja Sathish Kumar,

Y. V. Balarama Krishna Rao

E-ISSN: 2224-266X

15

Volume 23, 2024

heavy load and cool starting periods, switch S1 is

always in ON condition. In the same way switch, S2

is in ON condition only during no-load periods on

the electric motor. At the time of sharing the extra

burden on the battery by UC, switch S3 will be in

ON condition and during the starting of the electric

motor.

3 Different Energy Management

Cases based on Load

The main circuit operation in four cases can be

represented in the above Figure 3, and for each case,

one separate circuit is plotted. In case-1, only switch

S3 is in the ON state, to meet the motor requirement

due to a heavy load which starts the BDC operation

as a boost. During case-2, switches S3, and S1 both

are in the enable state, and S2 is in the OFF state.

This starts the operation of both converters under

boost mode. In case 3, after applying the desired

load, the action of the UDC works as boost, and no

operation is required from BDC. Finally, no load is

applied in the fourth case, due to which the battery

is capable of supplying energy to load UC as well.

Therefore, during the last case S1, and S2 both are

in an ON state to fulfill the load demand.

Fig. 3: Main circuit with BDC as well as UDC

converters including switches (a) case-1 (b) case-2

(c) case-3 (d) case-4

4 Implementation of Proposed

Control Strategy

This control strategy mainly consists of two

controllers in which the CBC plays a vibrant role to

obtain the smooth transition of energy source. On

the other hand, a conventional/intelligent controller

is required to produce a switching signal related to

the load on the motor. Besides, the CBC will send

the controlled signals to the converters according to

the vehicle dynamics. The CBC can be realized

based on four different speed conditions, which

describe the system performance during all load

conditions.

4.1 Realizing CBC Controllers with Four

Math Functions

The design of the CBC is mainly by considering

four math functions separately related to the drive’s

speed. Different load conditions are considered, and

various speed regions are also classified, with all

those speed regions, a CBC is considered which is

useful to produce the controlled pulse signal to

switches existing in BDC and UDC.

(a) During the first case of operation, the speed of

the motor is 4800 rpm due to the huge load

applied which initiates output of math

function U1 as 1” and “0” for other math

functions.

(b) In the second case, more than a normal load is

applied due to that, the speed of the motor

maintains between 4600 rpm and 4800rpm.

This attempt initiates the math functions U1,

and U2 outputs as one and zero for the other

two math functions.

(c) Case three is related to the rated load applied,

due to the motor’s speed sustained between

4801 rpm to 4930 rpm. Math function U3

only generates an output signal as one and the

remaining math functions produce output as

zero.

(d) In the fourth case, the motor’s speed is greater

than or equal to 4931rpm due to no load

applied. Two math functions U1, and U2

generates output as one and the other two U3,

and U4 math functions generate output signals

as zero.

(a)

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DOI: 10.37394/23201.2024.23.2

Venkata Koteswara Rao N, Raja Sathish Kumar,

Y. V. Balarama Krishna Rao

E-ISSN: 2224-266X

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Volume 23, 2024

(b)

(c)

(d)

Fig. 4: Flow chart representation of control strategy

(a) for case one (b) for case two(c) for case three (d)

for case four

Figure 4 (a), (b), (c) and (d) shows the flow

chart representation of the four modes of the

operation applied with proposed control technique

and which clearly shows the energy sources ON and

OFF states of the system.

4.2 Realizing Control Strategy with CBC

Controller

(a)

(b)

(c)

(d)

Fig. 5: Pulse signals produced to DC-DC converters

by the designed control strategy approach (a) Circuit

for BDC operation under boost mode (b) Circuit for

UDC as well as BDC operation under boost mode

(c) Circuit for UDC operation under boost mode (d)

Circuit for BDC (buck) as well as UDC (boost)

WSEAS TRANSACTIONS on CIRCUITS and SYSTEMS

DOI: 10.37394/23201.2024.23.2

Venkata Koteswara Rao N, Raja Sathish Kumar,

Y. V. Balarama Krishna Rao

E-ISSN: 2224-266X

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Volume 23, 2024

Figure 5(a) shows how the pulses are produced

to the UDC to propel the EV from the battery only.

In this case, no operation is required from the BDC

because; the motor is running under rated load.

Figure 5(b) shows how the signals are produced to

UDC (boost) as well as BDC (boost). Figure 5(c)

represents how the signals are produced to UDC

(boost). Figure 5(d) shows how the signals are

produced to UDC (boost) as well as BDC (buck).

The proposed technique has been modeled

based on four outputs of CBC (U1, U2, U3, U4)

which are obtained from the input speed of the

motor at different load conditions. The objective

function is formulated as:

)(,,, 4321 xfUUUU 

(1)



















rpmxU

rpmxrpmU

rpmxrpmUU

rpmxU

xf

4931;

49304801;

48004600;&&

4800;

)(

4

3

21

1

(2)

5 MATLAB/Simulink Results with

Comparison

The MATBAL/Simulink model output results are

attained corresponding to four cases of operation

based on the motor’s speed. Figure 6, Figure 8,

Figure 10, Figure 12, Figure 14, Figure 16, Figure

18 and Figure 20 represents the current and speed

responses of the motor with CBC plus FLC as well

as CBC with PID. In each case corresponding load

is applied which creates the distortions in speed as

well as current. In the same way Figure 7, Figure 9,

Figure 11, Figure 13, Figure 15, Figure 17, Figure

19 and Figure 21 corresponding to how the

switching signals are generated during starting and

transient periods, all those obtained with different

load conditions.

5.1 Case-I

Fig. 6: Output responses of the motor corresponding

to CBC with FLC

During starting, the motor draws a huge current

to obtain the required speed. In this case, of

operation, a heavy load is applied, which causes the

rise of current value and decrement of speed up to

0.2 sec. Thereafter motor reached the stable state by

the CBC plus FLC.

Fig. 7: Representation pulses to BDC and UDC by

the CBC with FLC

Figure 7 shows how the controlled switching

pulses are producing the DC-DC converts

corresponding to vehicle dynamics. During the

starting of the motor, the controlled pulses are

produced to BDC (boost) up to 0.15 sec. After the

motor reaches the normal state, it initiates the

production of signals to BDC (buck) and BDC

(boost) until load is applied. A heavy load is applied

at 2.5 sec, due to that motor speed being reduced,

and the current value is raised to 0.2 sec, which

starts the process of BDC (boost) and no switching

signals to UDC.

Fig. 8: Output responses of the motor corresponding

to CBC with PID

Fig. 9: Representation pulses to BDC and UDC by

the CBC with PID

WSEAS TRANSACTIONS on CIRCUITS and SYSTEMS

DOI: 10.37394/23201.2024.23.2

Venkata Koteswara Rao N, Raja Sathish Kumar,

Y. V. Balarama Krishna Rao

E-ISSN: 2224-266X

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5.2 Case-II

Fig. 10: Output responses of the motor

corresponding to CBC with FLC

Fig. 11: Representation pulses to BDC and UDC by

the CBC with FLC

Fig. 12: Output responses of the electric motor

corresponding to CBC with PID

Fig. 13: Representation pulses to BDC and UDC by

the CBC with PID

5.3 Case-III

Fig. 14: Output responses of the electric motor

corresponding to CBC with FLC

Fig. 15: Representation pulses to BDC and UDC by

the CBC with FLC

Fig. 16: Output responses of the electric motor

corresponding to CBC with PID

Fig. 17: Representation pulses to BDC and UDC by

the CBC with PID

5.4 Case-IV

Fig. 18: Output responses of the motor

corresponding to CBC with FLC

Fig. 19: Representation pulses to BDC and UDC by

the CBC with FLC

WSEAS TRANSACTIONS on CIRCUITS and SYSTEMS

DOI: 10.37394/23201.2024.23.2

Venkata Koteswara Rao N, Raja Sathish Kumar,

Y. V. Balarama Krishna Rao

E-ISSN: 2224-266X

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Volume 23, 2024

Fig. 20: Output responses of the motor

corresponding to CBC with PID

Fig. 21: Representation pulses to BDC and UDC by

the CBC with PID

Fig. 22: Representation of a hybrid controller’s

performance with their steady-state reaching times

corresponding to each case

Figure 22 shows that the stable state reaches the

time of individual controllers. In the first three

cases, CBC with FLC took less time to reach the

normal state (maximum time is 0.25 sec and the

minimum time is 0.05 sec) whereas CBC with PID

took more time to attain the original state (In the

first case the wave not settled at normal state, case-2

took 1.2 sec, in case-3 0.8 sec).

6 Conclusions

By combining CBC with the PID/FLC controller, a

control strategy has developed to attain the

automatic transition between two sources in MESS.

For successful operation, the main circuit is

simulated in four modes based on various loads. The

two-hybrid controllers CBC with FLC, and CBC

with PID are realized to the main circuit in all

modes of operation and obtain satisfactory results.

In case one CBC controller produced switching

signals as “1” for the output of CBC U1 and “0” for

other outputs, which started the action of BDC as a

boost, no pulses are developed to UDC. During case

two, math functions U1, and U2 produced output as

one, which started the process of BDC and UDC as

a boost. In case three, CBC produced a signal as “1”

from outputs U3 and “0” for other math functions,

which initiated the operation of UDC as boost, no

signals are produced to UDC. During case four,

CBC produced output signals as “1” for math

function U4 and “0” for other math functions, which

begins the operation of BDC (as a buck) and UDC

(as boost). Two-hybrid controllers are taken at

different times to reach the original state during

starting as well as the sudden load applied

conditions. Thereafter comparative analysis has

been done between the two-hybrid controllers based

on the different time domain specifications to

identify the performance of the individual

controller, those are represented in graph form in the

conclusion section.

Fig. 23: comparative study between two hybrid

controllers corresponding to the current taken by the

individual controller, in each case

Figure 23 represents the current taken by the

individual controller corresponding to the load

applied.

Fig. 24: Performance analysis of hybrid controllers

based on time-domain specifications

Figure 24 is the time domain-based comparison

between two controllers that are adopted to attain

the control objective. Individual controller related

time response is represented clearly in the Figure

25.

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DOI: 10.37394/23201.2024.23.2

Venkata Koteswara Rao N, Raja Sathish Kumar,

Y. V. Balarama Krishna Rao

E-ISSN: 2224-266X

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Volume 23, 2024

Fig. 25: Steady-state reaching time is taken by the

individual controller with and without load

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Contribution of Individual Authors to the

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Policy)

The authors equally contributed to the present

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problem to the final findings and solution.

Sources of Funding for Research Presented in a

Scientific Article or Scientific Article Itself

No funding was received for conducting this study.

Conflict of Interest

The authors have no conflicts of interest to declare.

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DOI: 10.37394/23201.2024.23.2

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E-ISSN: 2224-266X

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