Lecture 6-3
Electrical Systems III
D’Aarsonval Meter
DC Motors
Brushed DC Motor
Brushless DC (BLDC) Motor
High efficiency, no voltage drop across brushes High output power/frame size.Because BLDC has the windings on the stator, which is connected to the case, the heat disipation is better
Higher speed range - no mechanical limitation imposed by brushes/commutator
Higher cost of construction
Electric Controller is required to keep the motor running Two wire control
Low cost of construction/ Simple and inexpensive control No controller is required for fixed speeds
At higher speeds, brush friction increases, thus reducing useful torque
Poor heat dissipation due to internal rotor contsruction Higher rotor inertia which limits the dynamic characteristics Brush Arcing will generate noise causing EMI
Other Motors:
Controller Motor
drive Motor Mechanical
system
u v T
5V 250V
Constitution of DC Servomotor System
PWM1 Q1
Q2
Q3
Q4
Q5
Q6
PWM3 PWM5
PWM2 PWM4 PWM6
DC+
v
u w
N S N H3 S
H1
R H2
Hall sensor output Current sensing
3 phase BLDC motor driver :
Motor drive system :
Motor Controller Guide rail
Elevator cage
Tail code Counter weight
Shock absorber
e + -
J p e rm a n e n t m a g n e t
E le c tric E n e rg y M e c h a n ic a l e n e rg y
DC servo motor : ex) Elevator structure :
Constitution of DC Servomotor System
if constant
: armature resistance, : armature inductance, H : armature current , A : field current , A
: applied armature voltage, V : back emf , V
: angular displacement of the motor shaft, rad : torque developed by the motor, N- m
: equiv
a a a
f a b
R L i i e e T J
2
alent moment of inertia of the motor and load referred to the motor shaft, kg- m
: equivalent viscous- friction coefficient of the motor and load referred to the motor shaft, N- m/rad/s b
Variables :
Armature Control of DC Servomotors
a
:
T K i K motor torque constant
b b b
:
e K d K back emf constant dt
a
a a a b a
L di R i e e dt
2
2 a
d d
J b T K i
dt dt
Armature Control of DC Servomotors
The torque of motor :
For a constant flux, the induced voltage :
Armature circuit D.E :
Inertia and friction :
if constant
2
( ) ( )
( ) ( ) ( ) ( )
( ) ( ) ( ) ( )
b b
a a a b a
a
K s s E s
L s R I s E s E s Js bs s T s KI s
. ( )
( ) ( )
( 1)
a
a a a b a b
a m
m
K R J
s K
T F E s s R Js R b K K R b K K
s s R J
K s T s
/ ( )
/ ( )
m a b
m a a b
K K R b K K motor gain constant T R J R b K K motor time constant
Laplace transforms of equations :
b b
e K d dt
a
a a a b a
L di R i e e dt
2
2 a
d d
J b T K i
dt dt
Armature Control of DC Servomotors
ex) servo-motor system
1 2
: armature resistance, : armature current , A : field current , A
: applied armature voltage, V : back emf , V
: angular displacement of the motor shaft, rad : angular displacement of the load shaft, rad : torque developed by t
a a
f a b
R i i e e
T
he motor, N- m
2 1
2 2
: equivalent moment of inertia of the motor, kg- m : equivalent moment of inertia of the load, kg- m J
J
T K i
ab b b
:
e K d K back emf constant dt
The torque of motor :
For a constant flux, the induced voltage :
Example of a DC Servomotor System
constant
1 Gear
2 Gear
a a b a
R i e e
2 1
1 1 2
2 eq
J J n J
n
( ) ( ), ( ) ( ) ( ) ( ), (
2) ( ) ( ) ( )
b b a a a b a a
K s s E s L s R I s E s E s Js bs s T s KI s
. ( )
( ) ( )
( 1)
a
a a a b a b
a m
m
K R J
s K
T F E s s R Js R b K K R b K K
s s R J
K s T s
Example of a DC Servomotor System
Armature circuit D.E : Inertia and friction :
Laplace transforms of these equations :
Electric Vehicle
Safety and Maneuverability Control Allocation for 4WD Electric Vehicle
• System Configuration
- Objective: Driving Control Algorithm for Maneuverability, Lateral Stability and Rollover Prevention - Main Controller Input: Human Driver Input, Measured Vehicle Signal
- Actuator: Front and Rear Driving Shaft Motors, Independent Brake Module
Rear wheel drive electric vehicle:
DC Motor
Motor selection
1. Max speed : 120 kph
2. Max accelerations: >0.6G
3. 0-100 kph : 8seconds
e-4WD Motor Specification
Motor power max
120 kW (Front)
45 kW (Rear)
Battery
capacity 47 kWh Motor
speed max 12000 RPM Motor torque max
280 Nm (Front) 120 Nm (Rear)
0 20 40 60 80 100 120
0 50 100 150 200 250 300
0 2 0.4 0.6
0 6 0.8
0.8 0.8
Vehicle Speed [kph]
Torque [Nm]
0 2 0.6 0 4
0 6 0.8
0.8
0.8
Tmax
OOL
0 50 100 150 200 250 300
0 20 40 60 80 100 120
0.8
0.8 0.8
0.9
0.9
0.9 0.9
0.9
Vehicle Speed [kph]
Torque [Nm]
Tmax
OOL
