Design and Control of Hybrid Energy Storage

System based Small Plug-in Electric Vehicle

Supervisor Phaneendra Babu Bobba,

Department of Electrical Engineering, Shiv Nadar University.

Students I. Malyala Varun, AAA0204, Electrical Engineering, Shiv Nadar University

II. Priyam Avasthy, AAA0212, Electrical Engineering, Shiv Nadar University

III. Vavya Chopra, AAA0232, Electrical Engineering, Shiv Nadar University

Contents

Abstract ............................................................................................................................................................................. 3

Block Diagram of the Project ............................................................................................................................................ 3

Power Management ......................................................................................................................................................... 4

Bidirectional Converter: ...................................................................................................................... 5

Simulation 1: Permanent Magnet Brushless DC Motor Drive .......................................................................................... 6

Speed Controller ............................................................................................................................................................... 7

Hysteresis Current Control ........................................................................................................................................ 7

Modes of Operation – Switching Logic [2] ........................................................................................................................ 8

Vehicle Dynamics [3] ......................................................................................................................................................... 8

Model parameters for simulation ..................................................................................................................................... 8

Results ............................................................................................................................................................................... 9

Hardware Implementation ............................................................................................................................................... 9

Driver circuit using IR2101 .................................................................................................................. 9

Hall Sensor Interfacing Circuit ........................................................................................................... 10

Generating PWM outputs from hall signals .................................................................................................................... 10

Simulation - Work Plan [4] .............................................................................................................................................. 11

Future Work .................................................................................................................................................................... 11

Abstract In this project, a hybrid system based on battery and super capacitor along with multi-port converter.

PMBLDC motor is used to drive the vehicle and it is operated in four quadrant mode i.e. forward and reverse

regenerative braking mode and motoring mode. Power transfer from different energy sources is controlled by multi-

port converter and a phase-shifted PWM technique is implemented to ensure the proper operation of the storage

devices based load requirements of the electric vehicle. For proper modelling and verification, a MATLAB based

simulation model is developed. Vehicle Dynamics are also incorporated for testing the performance of the electric

vehicle. For the hardware implementation, TI controller TMDSPREX28335 is used as a central control unit to monitor

the control variables and also to generate switching pulses to the inverters and multi-port converter based on load

requirement.

Block Diagram of the Project

Power Management In this particular project, 16.2V, 58F ultracapacitor has been used in the circuit to ensure the prototype speed of 15kmph. Ultracapacitor has an internal series resistance and a significantly high resistance in parallel. The ultracapacitor model was implemented in MATLAB using the given circuit to analyze the charging and discharging pattern and check the same for a real-time application. A capacitor (with a very small series resistance) and a significantly large parallel resistance was connected to a DC

power source and resistive load through two switches who were activated by out-of-phase pulses (from the

generator). When the first switch was ON, the supercapacitor was discharged against the load. During the turn OFF

instant of the first switch, the second switch was turned on the capacitor was charged by the battery.

First graph indicates the charging/discharging characteristics of the capacitor against a load of 100 ohms. The second

graphs is the overlap of the pulse given to the second switch (for charging) and the charging instant of the capacitor.

The charging and discharging time for the hardware model of the supercapicitor were calculated using the following

circuit. The resistance was maintained such that no more 2A could flow within the circuit. The DC voltage was

maintained to provide a current of minimal value so that the capacitor (which has low resistance) does not get

damaged

Following are the DSO outputs indicating the charging and discharging pattern of the hardware supercapacitor

circuit.

Bidirectional Converter:

This is the simulation of bidirectional converter. However it’s still not working in motoring and regenerating mode.

.The values used here for different parameters has been calculated using formulae and some assumptionsValue of

capacitance is decided in accordance with the current it can allow to pass through it without any damage and will

reduce ripple and very small values of resistors are used because voltage source and capacitor can never be

connected in parallel

Simulation 1: Permanent Magnet Brushless DC Motor Drive

Speed Controller

Current Control [1]

Hysteresis Current Control

Modes of Operation – Switching Logic [2]

Vehicle Dynamics [3]

Model parameters for simulation Battery: Nominal_Voltage = 48;Rated_Capacity = 20;Initial_SOC = 80; Control: Speed_Cutoff_Freq = 285;Speed_Proportional_Gain = 4.9220; Speed_Integral_Gain = 446.7600;Speed_Torque_Saturation = [-17.3000, 17.3000]; Speed_Cutoff_Freq_Reg = 285;Speed_Proportional_Gain_Reg = 4.92; Speed_Integral_Gain_Reg = 446.76;Speed_Torque_Saturation_Reg = [-17.3000, 17.3000]; Hysteresis_Band = 0.0100; Hysteresis_Band_Motoring = 0.01;Hysteresis_Band_RegBrake = 0.01 ; Inverter: Rs = 66; Cs = 3.0000e-07; Motor: Rs = 0.1800; Ls = 5.4000e-04; Flux_Linkage = 0.0276;Inertia = 0.1324;Viscous_Damping = 0.0516;Poles = 23; Ke = 133; Vehicle Dynamics: Mass = 175; Tire_Radius = 0.2000;Aero_Drag_Coeff = 0.9200; Frontal_Area = 0.6000; Wind_Velocity = 0; Air_Density = 1.2300; Gravitational_Constant = 9.8100; Gradient_Angle = 0; Rolling_Resistance = 0.0180;

Results

Hardware Implementation For the presented application, the TMS320C28335 DSP is chosen. It consist on a logic integrated circuit mounted in

an auxiliary board (F28335 Zdsp). This device provides the necessary supply connections for the TMS320c28335 to

be run and programmed. The DSP clock is of 150 MHz and needs to be supplied with 3.3 V. It is able to do hardware

PWM signals and includes several ADC converters. The DSP is programmed in Simulink interface which in turn

generates C code. Code Composer Studio compiler is used to compile and interface between the system and the

controller. Using this programmable device to control the converter assures enough computation speed and it also

has the advantage that it can operate with floating point, therefore, operations are very easily done.

Driver circuit using IR2101

For the hardware part, we have one leg of converter and to run it we have made a driver circuit using IC IR2101.

The circuit is complete but when we tried giving it pulses through function generator, it didn’t work because of the

current rating being very low.

We have designed RC snubber circuit to connect across switching device to limit the dv/dt.

We have used these values : 𝐼 𝑝𝑘 = 25 𝐴, 𝑉𝑟𝑎𝑖𝑙 = 15 𝑉 , 𝑟𝑖𝑠𝑒 𝑡𝑖𝑚𝑒 = 𝑑𝑡 = 50𝑛𝑠 , 𝑓 = 20𝑘𝐻𝑧

And got this results, C =66.66 nF, R = 37.5 ῼ P = .15 W

Since the power is very low, we have used normal resistors for this purpose.

Hall Sensor Interfacing Circuit

Generating PWM outputs from hall signals

2 Output: Hall PWM Output Ha Ha

2 Hall Sensor Interfacing Circuit using TLC272CP

Simulation - Work Plan [4] All the parameters for this simulation are taken from standard research papers. Modelling of speed and

current controllers have been done using PI controller with some more features. Speed PI gain values have been

optimised using Ziegler - Nichols tuning method. Current controller although is a PI is just used for limiting range

between zero and one. In the current controller, hysteresis current control and pwm current control have been used

and performance is analysed and pwm current control has been selected for further research work. The forces which

the electric machine of the vehicle must overcome are the forces due to gravity, wind, rolling resistance, and inertial

effect and the EV propulsion system is modelled to meet the design requirements.

Various machine parameters such as rotor resistance, rotor inductance, inertia of the machine and voltage

constant have been measured. Controller has been successfully interfaced with Simulink and Code Composer Studio.

Hall sensor to controller interfacing circuits and gate driver circuits have been fabricated and tested. Decoder pulses

have been successfully generated and brushless dc motor is run in open loop using hall signals successfully.

Future Work The power circuit will be integrated with the motor and the close control loop. The values of currents,

battery’s state of charge and voltage will be fed back by the control circuit to the converter and the acceleration and

retardation will be determined on the basis of the above parameters. The control of switches and designing of speed

and current controller for the bidirectional converter such that the converter will operate in four quadrant is to be

done. After which we have to give switching pulses to the one leg converter and we will have to integrate the load

with the Bi- directional converter.

Current PI will be tuned accordingly to reduce the ripple and optimise power using Ziegler - Nichols tuning

method. In Vehicle Dynamics, state flow model for a hybrid sources depending on speed and acceleration or brake

mechanism is proposed for a better implementation. Mechanical braking and simulation for a full urban cycle will be

included in the future simulation. Rigorous regenerative braking algorithms will be implemented for effective

braking.

Current sensors and voltage sensor should designed to meet the requirement of the controller and will be

fed into ADC of the controller. Various control algorithms should be implemented to incorporate current feedback

into the existing system. Speed measurement should be done by configure the eCAP pins in the controller to

incorporate speed feedback into the system.

Bibliography

[1] C. B. Roger, E. Mehrdad and M. J. Thomas, Four-Quadrant Brushless ECM Drive with Integrated Current

Regulation.

[2] Y. Ming-Ji, J. Hong-Lin, M. Bin-Yen, Kuo-Kai and Shyu, A Cost-Effective Method of Electric Brake With Energy

Regeneration for Electric Vehicles.

[3] M. Ehsani, K. M. Rahman and H. A. Toliyat, Propulsion System Design of Electric and Hybrid Vehicles.

[4] J. Faiz, M. Azizian and M. Aboulghasemian-Azami, Simulation and analysis of brushless DC motor drives using

hysteresis, ramp comparison and predictive current control techniques.

[5] P. PRGASAN and R. KNSHNAN, Modeling of Permanent Magnet Motor Drives.

[6] R.Krishnan, Permanent Magnet Synchronous and Brushless DC Motor Drives.