DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING

ELEC 6491: CONTROLLED ELECTRIC DRIVES

Report on

DESIGN OF AN ELECTRIC DC MOTOR VEHICLE

Submitted By Submitted To

Name : Seratul Islam DR. MAHER AL-BADRI

IDCourse No

: 27735030: ELEC6491

1

Table of Content:

1. Abstract ………………………………………………………………. 22. Introduction …………………………………………………………….... 23. Machine Parameter ………………………………………………………………. 24. Vehicle Specifications ………………………………………………………………. 35. Acceleration Profile ………………………………………………………………. 36. Drive Cycle Definition ………………………………………………………………. 37. Inertia (linear & rotational) ………………………………………………………………. 48. Torque Component ………………………………………………………………. 49. Operating Envelope ………………………………………………………………. 5

Time VS speed curve ………………………………………………………………. 5 Speed VS Torque curve ………………………………………………………………. 5

10. Ratings of the component ………………………………………………………………. 7 Diode ………………………………………………………………. 7 Inductor ………………………………………………………………. 8 IGBT Switch ………………………………………………………………. 8 Capacitor ………………………………………………………………. 8 IGBT Driver ………………………………………………………………. 9

11. Controller ………………………………………………………………. 912. DC-DC Boost Converter ………………………………………………………………. 913. DC-DC Buck Converter ………………………………………………………………. 1014. Cable Size and Length Specification …………………………………………………………. 1015. Sensor and Transducers ………………………………………………………………. 1116. Selection of gear ratio ………………………………………………………………. 1217. Schematic Diagram ………………………………………………………………. 1318. Battery Bank ………………………………………………………………. 1319. System Wiring Diagram ………………………………………………………………. 1420. Parts Lisl ………………………………………………………………. 1421. Controller Design ………………………………………………………………. 1422. DC motor Block Diagram ………………………………………………………………. 1523. Simulation on Matlab Simulink ………………………………………………………………. 1524. Outputs (Voltage, Current, speed) …………………………………………………………… 1625. Discussion ………………………………………………………………. 1726. Conclusion ………………………………………………………………. 1727. References ………………………………………………………………. 17

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A b s tr a c t :

The traditional DC (Direct Current) electric motor driving a car is a simple machine consisting of a case containing a fixed electrical part, the stator (called the stator because it is static and comprising what is called the field coils) and a moving electrical part, the rotor (because it rotates) or armature as it is often called. As the rotor turns, it turns a pinion which drives a gearwheel. The gearwheel is shrunk onto the axle and thus drives the wheels. The motion of the motor is created by the interaction of the magnetism caused by the currents flowing the stator and the rotor. This interaction causes the rotor to turn and provide the drive. The most important reason behind using DC motor is it provided the right torque characteristic for car operation and was reasonably simple to control.I n t r o d u ct i on :

In part one according to given machine parameter we select the vehicle mass, axels, wheels and number of motors. After that we calculated different torque and inertia. Based on torque and speed we define drive cycle and acceleration profile. In addition, we define operating envelope based on acceleration and deceleration profile as well as gradient. In part two the main components used to drive the selected vehicle are discussed in different sections. The components such as DC to DC converter are used to boost the voltage from battery to motor and its appropriate device ratings are mentioned for the rated values. Cables length specification are selected to enhance the efficiency in motors, power converters and auxiliary battery respectively. Sensors are used to detect the speed, current, and voltage in the system. After that, gear ratio is selected and its operation is illuminated briefly. Schematic diagram and system level wiring diagram are drawn. In the final part we define current loop. Then we simulate it on matlab simulink to observe rated speed, current and voltage.

Machine Parameters

Rated Speed 1150 Rpm

Power Rating 40HP

Armature Rated Current 146 A

Armature Resistance 0.0964Ω

Armature Voltage 230 V

Armature Inductance 2.0mH

Moment of Inertia (J) 0.560Kg.m2

Frictional Co-efficient (B) 0.015 N.m.s / rad

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Vehicle Specifications

Fig-1: Selected vehicle[6]

Back Emf (Ea) = VT–IaRa = 230 – 146*.0964 = 215.92 V

Rated torque (T) = P/Wb = 29840/120.37 = 247.9 N-m

Physical parameters of selected vehicle are given below.

Mass of the Vehicle = 950 Kg

Radius of the Tire(r) = 0.14m

Maximum speed of the Vehicle = 70 Km/Hr.

Mass of one wheel Mw

Number of motors (n1)

=

=

10Kg

3

Number of wheels = 4

Number of axels (n2) = 2

Acceleration profile:Presuming that the Vehicle is accelerating to the maximum speed of 70Km/hr. in 18 seconds, then

Acceleration (a) = V− Vo

Drive Cycle Defination:

= 70

Km / hr 18

=

19. 44 18= 1.08 m/s2

Selected vehicle is taken to a test drive from Concordia University to LionelGrilox. The vehicle

is accelerated at starting point with an acceleration of 1.08 m/s2.There is three turning points

4

where the vehicle is decelerated and then accelerated. The corresponding path taken for test drive

condition is shown below.

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Fig-2: Test Drive[9]

Inertia (linear and Rotational)

Moment of Inertia Exerted on the wheel (J) ==

n* 1

*M r22 w*

4 * 0.5 * 10 * (0.14)2

= 0.392 Kg.m2

Load Inertia = m * r2

= 950 * (0.14)2

= 18.62Total Inertia = Load inertia + Inertia due to wheel

= 18.62 + 0.392= 19.01

Inertia Referred to load side ==

(1⁄6) ^2 * 19.010.528Kg.m2

Total Inertial referred to the load side = Inertia of the gear + Total inertiaReferred to load side

= 0.56 + 0.528= 1.088 Kg.m2

Torque ComponentThe Torque at the Motor Coupling Tm required to accelerate the vechice horizontally with the acceleration of 1.08m/s2

Tm = m*a*r

= 950 * 1.08*0.14

= 143.64Nm

The Gradient torque is Given by TG = Gmgr

= 0.4* 950* 9.8* 0.14

= 521.36Nm

The Rolling Resistance ofordinary car tires on concreteliesbetween(0.01 to0.015).

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The Rolling Torque Tr = Cr * m * g * r

= 0.013*950*9.8*0.14

= 16.94Nm

The Torque exerted on the axle of the wheel Tw = ∗𝑎

= 0 . 3 92∗1 . 08

= 3.024 Nm0.14Frictional torque TF = B * ω

The Total load torque required to accelerate the vehicle

TL = Tm+ Tg+ Tr+ Tw + Tf

= 0 . 0 15

∗2 ∗∗ 1 1 5060=4.51N.m

= 689.474 Nm= 143.64 + 521.36 + 16.94+3.024 +4.51

Gear Ratio: = 𝑎

= 689.4 74

= 2.78 ≈ 3247.9Operating Envelope:

Fig-3: Time VS Speed Curve

Fig-4: Speed VS Torque Curve

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Part 2:

When vehicle is running without any payload on horizontal surface the minimum load condition in the motor arises.

Vehicle payload = 453.6 Kg

Mass without payload = 950 – 453.6

= 496.4 Kg

Required torque to accelerate the vehicle without payload

Ta = m*a*r

= 496.4*1.08*0.14

= 75.05N.m

Tg (gradiant torque) = 0.

Tr (rolling torque) = Cr*m*g*r

= 0.013*496.4*9.8*0.14

= 8.85N.m

Load Torque (TL) = Tw+ Tg+ Tr+ Ta +Tf

= 3.024+0+8.85+75.05+4.51

= 91.43N.m

After reflecting through the gear, the difference of the vehicle mass reduced, so we can assume torque will remain same to pass the inertia.

Torque at minimum load conditions = 91 . 43 3(gear ratio)

= 30.48N.m

Motor torque = Kia

At rated condition Eb = Vt - IaRa

= 230 – 146*0.0964

= 215.92 V The Constant K =

215 . 92 120.37= 1.79

Required current to induce Ia =

8

= 30 . 481.79

9

= 17.02A

Assume efficiency of the motor is = 92%

So, the current Ia1 = 17 . 020.92

= 18.5 A

The minimum level of inductance required to sustain this current can be represented by the below equation.

Minimum Inductance (L) = ( 𝐕 − 𝐕 )(𝟏 − 𝐃) × 𝛈(𝐈𝐚)×𝐟

Duty Cycle of the converter (D) = 1 - 120 230

= 0.478

If the efficiency increase like 95% then D = 0. 4780.95

= 0.503

Thus, minimum inductance (L) = ( 230 − 120 )(1− 0. 503 )18.5×8000

= 0.369mH

Therefore, we can use 0.4mH inductor.

Ratings of the Component:Diode:

Fig-5: Boost Converter

Parameter Value

Manufacturer Vishay Semiconductors

Model VS-70HF(R)

DC blocking voltage 600V

Continuous Forward Current 30A

1

Package DO-219AB (SMF)

Two diodes are connected parallel in the circuit to sustain the forward current of 60A.

Inductor:

Parameter Value

Manufacturer LC magnetics

Typed Gapped inductor

Inductance 0.4mH

DC current 1200A

DC Resistance of Coil 0.00055Ω

Winding Dissipation 786W

IGBT Switch:

Parameter Value

Manufacturer Fairchild

Model FGH40T120SMDL4

Collector-to-Emitter Voltage 1200V

Continuous Collector Current (at 25C) 80A

Continuous Gate-to-Emitter Voltage ±25V

Pulse Collector Current, VGE = 15V 160A

Transient Gate-to-Emitter Voltage ±30V

Maximum Power Dissipation (at 25C) 555

Capacitor:

The capacitor value should be under control as it can increase the set up time of the system.

Parameter Value

Manufacturer Cornell Dubilier

Model 7P301V330J032

Type Aluminum Electrolytic capacitors

Rated Voltage 360V

Leakage Current 1 times C in µA maximum at 5 min.

Rated Capacitance 500 h @ +70 °C Capacitance 10% of limit

1

Capacitance tolerance ±20%

Temperature range –20 °C to +55 °C

IGBT Driver:

For conducting IGBT we need driver circuit to apply proper gate voltage and for generating duty cycle to operate at 5V we need controller circuit but the gate voltage is around 5 V. So, gate driver circuit’s converts 5V control signal to power signal that can drive the IGBT

Parameter Value

Manufacturer Semikron

Channel Single IGBT driver

Input Supply 15V

5V Logic Level High/Low 2.4V/0.5V

Collector Emitter Voltage Sense 1200V

Charge per pulse 9.6μC

Table: IGBT driver specifications

Controller:

A controller is necessary to execute several function. First of all, controller is designed to control the motor. The controller sensor monitor the motor speed and motor input current. The controller also regulate the brake and acceleration and cuts the power from the power converter and turns on the back and front lights correspondingly.

DC-DC Boost Converter:

The 15V DC-DC converter module is desirable to provide the indispensable input voltage to the gate driver circuit. This converter is connected to the auxiliary battery that supplies to all the peripherals and the controller.

Parameter Values

Manufacturer Murata

Model NDY1215C

Input Voltage 12V

Output Voltage 15V

Full Load current 200mA

Efficiency 82%

Maximum output power 0.58A

Table: Dc-Dc boost Converter specifications

1

DC-DC Buck

The 5V DC-DC buck converter module is needed to supply power to the controller.

Parameters Values

Manufacturer AVANSYS

Model AV10-12S05

Input Voltage 12V

Output Voltage 5V

Maximum Output current 2A

Efficiency 79%

Table 7: DC to DC buck convertor module

8. Cable size and Length specification

Cable size has been selected for corresponding motor, convertor, and auxiliary battery rated values. To prevent from low efficiency and for the safety purpose of the components. Particular length is selected to reduce the losses, over weight.

8.1 Battery - Power converter side cable size and length specifications

In this part cable is selected from battery to power converter side input voltage is 12 volts and input current is 200 amps and the length is assumed to 1.8 meters. These values are calculated through online website [1 ]

SIZE DIAMETER RESISTANCE (25OC) Resistancefor 1.8m(ohm)

VoltageDrop(V)

OutputVoltage

(V)

%LossAWG mm2 Inch Mm Ohm/1000’ Ohm/km

6 13.302 0.1871 4.753 0.4023 1.302 0.00238 0.4760 11.5240 3.976Table: Cable size and length specification of battery to power converter

8.2 power converter – Motor side cable size and length specifications

Here cable is selected from power converter to motor side input voltage 230 volts and input current 146 amps and the length is assumed to 1.8 meters. These values are calculated through online website [ 1]

SIZE DIAMETER RESISTANCE (25OC) Resistancefor 1.8m(ohm)

VoltageDrop(V)

OutputVoltage

(V)

%LossAWG mm2 Inch Mm Ohm/1000’ Ohm/km

20 0.518 0.0369 0.983 10.3632 34 0.0612 8.935 221.065 3.885Table: Cable size and length specification of power converter to motor

8.3 Auxiliary battery cable size and length specifications

In this part cable is selected for auxiliary battery input voltage is 12v volts and input current is 20 amps and the length is assumed to 1.8 meters. These values are calculated through online website [1 ]

SIZE DIAMETER RESISTANCE (25OC) Resistance Voltage Output %

1

AWG mm2 Inch Mm Ohm/1000’ Ohm/km for 1.8m(ohm)

Drop(V)

Voltage(V)

Loss

14 2.081 0.0740 1.880 2.5756 8.450 0.01521 0.30420 11.6958 2.535Table: Cable size and length specification for Auxiliary battery

9. Sensors and transducers:

There are three types of sensors are used namely speed, voltage and current

9.1 Speed sensors

The Speed on the motor shaft needs to be fed to the Motor controller as a feedback and for

control operation. The sensor is placed near the motor shaft and it works on the Hall Effect

principle and gives a digital signal for the motor controller. This speed sensors are selected for

the rated values from the website [2 ]

Parameter Value

Input voltage (Vdc) 4.5 to 25 volts

Input current (mA) 10 amps

Output voltage low (Vdc) 0.4 - 0.6 volts

Output current (mA) 20 sink

Pull up resistor 4.7ohms

Table Speed sensors specifications

9.2 current sensors

Current sensors is used to measure the indirect torque measurement and to detect the current in

the cable or wire. The current sensors are selected for the rated values from the website[ 2].

Parameter Value

Manufacturer Honey well

Rated current 25Amps

Sensing current range ±56 Amps

Coil turns 2000(50ohm coil)

Response time <0.2 µs

Pinout style unipolar

Operating temperature range -40 °C to 85 °C [-40 °F to 185 °F]

Table current sensors specification

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9.3 Voltage sensors

Voltage sensors is used to detect the battery and motor terminal voltage. The voltage sensors are

selected for the rated values from the website [2 ].

Function Range Resolution Accuracy

(Volts) voltage rating

200V 0.1mV

±(0.8% reading+3.5 digits)2V 1mV

20V 10mV

200V 100mV

500V 1V

Table: Voltage sensors

10. Selection of gear ratio based on standard gears:

In this system reduction gear is used to reduce the speed and increase torque. Hence the gear

attached to the wheel is larger than the gear attached to the axle.The gear is selected according to

the gear ratio calculated from the previous section of the report. The gear ratio is selected as to

match the torque required by the vehicle at operation and the full load torque that can be supplied

by the motor.

Gear Ratio: =𝑜𝑎 𝑜 𝑜 𝑜 𝑜

= 689 .474

= 2.78 ≈ 3247.9A 1:3 gear ratio is typically achieved using a gear having a higher number of teeth’s proportional

to the same ratio. Generally a 16:48 gear teething is selected.

Fig-6: gear ratio[6]

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11. Schematic Diagram:

Fig-7: Vehicle Control Diagram

Ba t te r y B an k:

We have provide large amount of power supply as continuous basis. Thus we use a series connection of battery for entire module as a battery bank

Rated current of the motor = 146A

Converter efficiency from the data sheet = 92%

Wiring efficiency = 99%

Depth of discharge allowed for battery for maximum performance = 80%

Battery efficiency = 91%

Current rating at the controller = 1461460.80∗0.92∗0.99∗0.91

= 220.17

Consider a 12V 200 Am of 10 such batteries are connected in series to increase the battery bank output voltage to 120V. If we charge the battery fully, it will approximately operate for 48 minutes.

Cell Material: Li-ionVoltage: 12VCapacity: 200AhDischarge Current: 200A(Max)Pulse Discharge Current: 400ACharge Current: 50A(Max)Charge Temperature: 0-45°COperation Temperature: 0-60°CDimension: Customized/ 520*269*203mmWeight: 30KGEfficiency 91%

Table: battery specifications [4].

1

S yst e m wi r i n g d i ag r a m:

1 3 . P a rts l i st

Fig-8: wiring diagram

Battery Bank 12V,DC-DC Converter –120/230VDC-DC Converter –12/5 VMotor ControllerSpeed SensorBattery Temperature SensorCurrent SensorSpeedometerBreak relayHead lamp, Tail LampHornFuseAuxiliary BatteryThrottlecables

Project Part: 3

C on t r o ller D e s i gn :

The motor speed depends on the amplitude of the applied voltage. The required speed is controlled by a speed controller, which is implemented as a conventional proportional-integral (PI) controller. We calculated the boost converter transfer function by using below equation[8]

𝑉𝑜 =𝑉 ( 1 − ) 𝑉𝑜 − ( 𝑙 ) ()2+𝐿 + (1−)2𝑅

1

Here, D=0.478

L, IL and C values are calculated by using daycounterwebsite[7] for boos converter.

So,𝑉𝑜 =

(1−0.478)230−(4890.13−6∗146.73)4890.13−6𝑉 (4890.13−6∗1097.35−6)2+

120.06−0.717

= 5.36−62+0.0507+ 0.272

0.0964 + (1−0.478)2

Dc motor Block Diagram:

Fig-9: DC motor

Simulation on Matlab Simulink:

Fig-10: MatlabSimuling Simulation Diagram

𝑎 Here, Kt= 𝑤 KW= 𝑤215.92= 120.37 =

247.9.37

120= 1.79 = 2.05

Rest of the two transfer functions are

Transfer function = 1

1

2∗10−3∗0.0964 Transfer function =

1 0.560∗0.015

1

Outputs:O u tp u t V o lta g e w a v efo r m

Fig-11: Voltage output waveform

O u tp u t c u r r e nt wa v efo r m

Fig: Current output waveform

O u tp u t S p eed wavef o r m

Fig: Speed output waveform

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D isc u s s i o n :

From the output voltage waveform it is lucidly shown that required output voltage is 230V. At first it started increasing exponentially and then it got stability at around 230V. From the current waveform we see it has started increasing rapidly and at certain stage it bounce back. After that current waveform goes for stable situation for particular time period. Again it went up rapidly and reached constancy at around 125A, which is close to the rated current 146A. While speed curb shows almost similar characteristics, started with exponential increase and exceeded the rated speed and then it came back to 1150 rpm. Throughout this project I face several difficulties. First of all, working on this topic, as it is my very first task on designing electric car, was very hard. Secondly, I got difficulties to operate Simulink simulation though it was not that hard.

Co n c lu sio n :

In this project report I tried to make feasible electric car by using dc motor. Here we calculate different torque and inertia to find the total load. After that we find gear ratio to accelerate to motor. Later we design the corresponding wiring diagram, schematic diagram and select the battery bank. Before that we select the rated component (e.g. capacitor, diode, IGBT switch) according to inductance from the website. In addition we use voltage, current and speed sensor to measure the outputs respectively. Also we design controller which is consist of boos converter transfer function

References:

[1] ht t p: / /ww w .bulkwir e . c om / wir e r e si s ta n ce . a sp

[2] ht t p: / /sensin g .hon e y w e l l . c om / hon e y w e l l - s e ns i n g - c ur r e n t - r a n ge - g uid e - 0 05918 - 3 -e n.pdf

[3] htt p:/ /cdn.polaris.com/orv/2016 /documents/P DFs/orv -2016-b rochur e-

[4] h t t p: / /ww w . a l i b a b a . c om / prod uc t - d e tail / 12 v - 2 00 a h - S ola r - B a t t e r y - L if e p o4- B a t t e r y _1867629825.h t m l ? spm= a 2700.7724857.29.12.A c Oo1p

[5] h t t p:/ / w w w . m u rat a - p s . c o m/ d a t as h e e t ? h t tp: // w w w. m u rat a - p s. c o m/ d a ta / p o w e r / n cl / k d c_n d y . pd f

[6] w w w . go o g le. c o m

[7] h t t p:/ / w w w.d a y c o un t e r .c o m/ Ca l cu l at o r s / Sw i tchi n g -C o n v e r t e r-Calc u l a t o r 2 . ph t m l

[8] h t t p s :/ / w w w . e ce.n u s. e du .s g / stfpa g e / a kr / ss m b o o s t. pd f

[9] h t t p s :/ / w w w . go o g le.c a / m a p s / d i r / C o n c o r d i a +Un iv e rsity + - +Si r +G e o r g e + W illi a m s

[10] http://www.railway-technical.com/drives.shtml