Transcript dc motor (brushes)

Motors & Motor Drivers
ECE 450
1
AC or DC Motors
• AC
– Few robots use AC except in factories
– Most of those that use AC first convert to DC
• DC
– Dominates in robotics
– Must be bidirectional
2
DC Motor Types
• Continuous-duty
(run continuously when power supplied)
– Brushed
– Brushless
– Servo
• Intermittent-duty
(power must be pulsed to run continuously)
– Stepper Motors
3
Motor Specifications
•
•
•
•
•
Operating voltage
Current draw
Speed
Torque
Stalling or Running Torque
4
DC Motor: Brush Motors
The most common.
Toys, battery powered tools, electric machines.
Stator (permanent magnets)
Brushes
5
Brush DC Motors
Identify:
•
•
•
•
Stator
Rotor
Brushes
Commentator
http://mot-sps.com/motor/tutorial/blac.html
6
Brush DC Motor
How does it work?
7
Pulse Width Modulation
(PWM)
Centered PWM
8
Brushless DC Motor
Identify:
•
•
•
•
Permanent Magnets
Rotor
Brushes
Commentator
http://mot-sps.com/motor/tutorial/blac.html
9
Brushless DC Motor
1.
2.
3.
4.
5.
6.
Housing
Laminated steel stack
Winding
Permanent magnet
Shaft
Ball bearing
1
6
6
2
5
3
4
Less common. Higher efficiency, less friction, less electrical noise.
Requires electronic driver.
10
Brushless DC Motor
How does it work?
11
DC Servo Motor
A DC Servo Motor is a DC Motor with
Gears and Electronics with limited
angular rotation (typically 90, 180 or 360º)
Why the addition of gears?
• Nylon
• Karbonite
• Metal
Why electronics?
• Digital
• Analog
http://www.societyofrobots.com/actuators_servos.shtml
12
DC Servo Motor
1
1.00 ms: 0 degrees
2.00 ms
1.50 ms
1.00 ms
0.50 ms
0.00 ms
1
1.50 ms: Neutral
0
2.00 ms
1.50 ms
1.00 ms
0.50 ms
0.00 ms
Requires constant pulsing
( 50 times / second)
0
1
2.00 ms: 180 degrees
0
2.00 ms
1.50 ms
1.00 ms
0.50 ms
0.00 ms
http://www.seattlerobotics.org/guide/servos.html
13
Stepper Motor
Very common. Required driver. Very strong, when not rotating.
Easy to control rotor position.
Full Step
Half Step
http://mot-sps.com/motor/tutorial/blac.html
14
Full-Step Stepper Motor
15
Half-Step Stepper Motor
16
Motor Drivers
Simple, 1- dc motor (brushes), on/off driver
+9 V
M1
DC Brush
D1
1N5817
(Schottky)
M
C
Q1
2222A
(NPN)
B
E
R1
1 k
On: to +9 V
Off: to GND or
disconnected
17
Transistors
PNP Bipolar Transistor
C
B
E
NPN Bipolar Transistor
C
B
E
http://www.kilowattclassroom.com/Archive/AN0007.pdf
18
Motor Drivers
Simple, 1-motor, on/off driver
+9 V
R2
1 k
E
Q2
2907A
(PNP)
B
On:
to GND or
disconnected
Off: to +9 V
C
M1
DC Brush
M
D1
1N5817
(Schottky)
19
Motor Drivers
Classic Bipolar H-Bridge
On:
Off:
to GND or
disconnected
to +9 V
On:
+9 V
+9 V
R4
1 k
E
B
Q4
2907A
(PNP)
D2
1N5817
(Schottky)
D4
1N5817
(Schottky)
Off:
to GND or
disconnected
to +9 V
R2
1 k
E
B
C
C
Q2
2907A
(PNP)
M
R3
1 k
Q3
2222A
(NPN)
C
B
D3
1N5817
(Schottky)
E
On:
Off:
to +9 V
to GND or
disconnected
Taken from Intermediate Robot Building by David Cook
M1
DC Brush
D1
1N5817
(Schottky)
C
Q1
2222A
(NPN)
R1
1 k
B
E
On:
Off:
to +9 V
to GND or
disconnected
20
Motor Drivers
Classic Bipolar H-Bridge
+9 V
R4
1 k
E
B
GND
from
microcontroller
1
NC
2
IN A
3
GND
4
IN B
4427
from
microcontroller
NC
8
OUT A
7
VDD
6
OUT B
5
Q4
2907A
(PNP)
D2
1N5817
(Schottky)
D4
1N5817
(Schottky)
R2
1 k
E
B
C
C
Q2
2907A
(PNP)
M
R3
1 k
Q3
2222A
(NPN)
C
B
E
Taken from Intermediate Robot Building by David Cook
D3
1N5817
(Schottky)
M1
DC Brush
D1
1N5817
(Schottky)
C
Q1
2222A
(NPN)
R1
1 k
B
E
21
Motor Drivers
Typical H-Bridge Motor Driver
+5 VDC
220 F
Disconnected or
from microcontroller
From microcontroller
ENABLE A&B
2
INPUT A
3
OUTPUT A
4
GND
M
OUT B
from
microcontroller
+4.5 to +36 VDC
220 F
5
GND
6
OUTPUT B
7
INPUT B
8
VMOTOR
SN754410
M1
DC Brush
1
VLOGIC
16
INPUT C
15
OUTPUT C
14
GND
13
0.1 F
From microcontroller
M
M2
DC Brush
GND
12
OUTPUT D
11
INPUT D
10
From microcontroller
9
Disconnected or
from microcontroller
ENABLE C&D
0.1 F
Taken from Intermediate Robot Building by David Cook
22
H-Bridge Lab
Components
1. Construct the H-Bridge as shown using components from your Robotics Kit.
2. Identify those configurations that short circuit the H-Bridge and on the
enclosed table enter “Short Circuit” under the Results column
3. Show this table to either the Instructor or the TA before proceeding any further.
4. Using your H-Bridge, determine how the motor performs under each of the 16
different combinations of the four transistors
–
DO NOT verify the short circuit combinations identified earlier!
–
Pay attention to the transistor numbering in the table compared to the schematic.
–
Be sure to identify whether or not the motor turns clockwise or counterclockwise
–
For any breaking actions, identify which direction the motor is turning when breaking occurs.
(In some configurations, breaking only occurs when the motor is turning in one direction but
not the other.)
5. Lab Report
–
To drive larger motors, an H-Bridge with higher capacity currents would be required. Using
the components in this lab, determine the component(s) that limit the current for driving a dc
motor. Describe your analysis and results in your lab report.
–
Include the table showing your results for the 16 different combinations for powering the HBridge.
23
Motor Drivers
Classic Bipolar H-Bridge
On:
Off:
to GND or
disconnected
to +9 V
On:
+9 V
+9 V
R4
1 k
E
B
Q4
2907A
(PNP)
D2
1N5817
(Schottky)
D4
1N5817
(Schottky)
Off:
to GND or
disconnected
to +9 V
R2
1 k
E
B
C
C
Q2
2907A
(PNP)
M
R3
1 k
Q3
2222A
(NPN)
C
B
D3
1N5817
(Schottky)
E
On:
Off:
to +9 V
to GND or
disconnected
Taken from Intermediate Robot Building by David Cook
M1
DC Brush
D1
1N5817
(Schottky)
C
Q1
2222A
(NPN)
R1
1 k
B
E
On:
Off:
to +9 V
to GND or
disconnected
24
H-Bridge Test Results
#
Q4
Q3
Q2
Q1
1
Off
Off
Off
Off
2
Off
Off
Off
On
3
Off
Off
On
Off
4
Off
Off
On
On
5
Off
On
Off
Off
6
Off
On
Off
On
7
Off
On
On
Off
8
Off
On
On
On
9
On
Off
Off
Off
10
On
Off
Off
On
11
On
Off
On
Off
12
On
Off
On
On
13
On
On
Off
Off
14
On
On
Off
On
15
On
On
On
Off
16
On
On
On
On
RESULT
25