1. DC otor & H Bridge 1

2. Outline DC Motor H Bridge Principle Speed Control Control Power 2
Figure 1. Real DC Motors 2

3. Principle Recap 3 Figure 2. Lorentz Force Direction
Figure 2. Lorentz Force Direction
Figure 3. Loop Current Diagram 3

4. Rotational Speed + - + - Assume it is a 6V motor 6V 6V 4
Figure 5. Macro View + - 6V
Figure 4. Voltage and Full Speed Rotation
commons.wikimedia.org  4

5. Rotational Speed - + - + Assume it is a 6V motor 6V 6V 5
Figure 5. Macro View - + 6V
Figure 4. Reverse Voltage and Rotation
commons.wikimedia.org  5

6. Rotational Speed - + - + Assume it is a 6V motor 4V 4V 6
Figure 5. Macro View - + 4V
Figure 4. Small Voltage and Slow Rotation
commons.wikimedia.org  6

7. Speed Control PWM % Duty Cycle ↓↓ % AVG Voltage % Speed 7
Figure 6. PWM Timing Diagram
PWM
% Duty Cycle ↓↓
% AVG Voltage
% Speed 7

8. But… Drive? VCC: ~3.3V Current: ~10mA Backwards? 8
Table 1. Specification of DC Gear Motor 8

9. H Bridge 9 Figure 7. H Bridge Diagram(
Table 2. H Bridge Functions ( 9

10. H Bridge
Figure 7. An H Bridge Diagram
Table 2. H Bridge Functions 10

11. H Bridge
Figure 7. An H Bridge Diagram
Table 2. H Bridge Functions 11

12. H Bridge
Figure 7. An H Bridge Diagram
Table 2. H Bridge Functions 12

13. H Bridge
Figure 7. An H Bridge Diagram
Table 2. H Bridge Functions 13

14. H Bridge
Figure 7. An H Bridge Diagram
Table 2. H Bridge Functions 14

15. H Bridge
Figure 7. An H Bridge Diagram
Table 2. H Bridge Functions 15

16. H Bridge
Figure 7. An H Bridge Diagram
Table 2. H Bridge Functions 16

17. H Bridge
Figure 7. An H Bridge Diagram
Table 2. H Bridge Functions 17

18. L298N Block Diagram
Figure 8. L298N Block Diagram (L298N Datasheet) 18

19. L298N Block Diagram (Left Half)
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) 19

20. Four Switches in H Bridge
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) 20

21. Figure 7. H Bridge Diagram
H Bridge’s Shape
Figure 7. H Bridge Diagram (
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) 21

22. Figure 7. H Bridge Diagram
Power Supply
Figure 7. H Bridge Diagram (
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) 22

23. Figure 7. H Bridge Diagram
Logic Power Supply
Figure 7. H Bridge Diagram (
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) 23

24. Figure 7. H Bridge Diagram
Inputs and Enable
Figure 7. H Bridge Diagram (
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) 24

25. Figure 7. H Bridge Diagram
Outputs
Figure 7. H Bridge Diagram (
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) 25

26. Table 2. H Bridge FunctionsM S1 S3 1 S2 S4 1
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet)
Table 2. H Bridge Functions ( 26

27. Table 2. H Bridge FunctionsM S1 S3 S2 S4 1 1
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet)
Table 2. H Bridge Functions ( 27

28. Table 2. H Bridge Functionsv M S1 S3 X S2 S4 X
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet)
Table 2. H Bridge Functions ( 28

29. Table 2. H Bridge FunctionsM S1 S3 S2 S4 1
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet)
Table 2. H Bridge Functions ( 29

30. Table 2. H Bridge FunctionsM S1 S3 1 S2 S4 1 1
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet)
Table 2. H Bridge Functions ( 30

31. Table 2. H Bridge FunctionsM S1 S3 S2 S4
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet)
Table 2. H Bridge Functions ( 31

32. Table 2. H Bridge FunctionsM S1 S3 S2 S4
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet)
Table 2. H Bridge Functions ( 32

33. Table 2. H Bridge FunctionsM S1 S3 S2 S4
Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet)
Table 2. H Bridge Functions ( 33

34. An example 40V GND 34 Figure 10. 30mm DC Motor from Maxon
Figure mm DC Motor from Maxon
Figure 11. SN Pin Connections (SN Datasheet)
Figure 12. SmartFusion FPGA
GND 34

35. What if we want to use a large-powered motor?
50V
Figure mm DC motor from maxon
Figure 13. L298N Pin Connections (L298N Datasheet)
It will likely burn the H-bridge! 35

36. Voltage Constraint (L298N)
Power Supply can’t be higher than DC motor
Logic Supply Voltage can’t be lower than FPGA output
Table 3. Voltage Constraint for L298N
DC voltage cannot exceed H-bridge voltage constraint 36

37. Power Constraint (SN754410)
Table 4. Voltage Constraint for SN754410 37

38. What if we want to use that large-power DC motor?
Build an H-bridge with 4 switches! 38

39. Which switch shall we use?
BJT
(Bipolar Junction Transistor)
Easier to build, use less circuitary
Good for low current operation VS
MOSFET
(Metal–Oxide–Semiconductor
Field-Effect Transistor)
Good for high current operation
When
H-bridge Motor cannot meet your power requirement
You don’t trust your integrated H-bridge
You need to build an H-bridge on your own!
Two options: BJT and MOSFET
BJT: Bipolar Junction Transistor
MOSFET: Metal–Oxide–Semiconductor Field-Effect Transistor
this-h-brigde-is-working
XrSeSVAb819HfhysOtYMdwDg3CTKXi6B
Figure 14. H-bridge with BJT
Figure 15. H-bridge with MOSFET 39

40. What is BJT? What is MOSFET? Don’t need to know
Ignore the mechanism (band diagram, Quantum Mechanics, Energy momentum diagram, semiconductor dopping)
Ref
Two diode. Two ways to connect them
PNP – active low
NPN – active high (Explain)
Base, Collector, and Emitter.
Small current can induce large current
First why?
BJT is resistive when on. It will generate heat, which will break them.
[What is MOSFET?]
Ignore the mechanism (even more complex than BJT)
BJT with a shell
NMOS – active high
PMOS – active low (Explain)
PMOS to Vdd, NMOS to Gnd
Second why?
It will reach saturation voltage, turn MOSFET into a big resistor, and consume large power and burn the gate.
PNP – active low
NPN – active high
NMOS – active high
PMOS – active low
Choose voltage/current wisely on gate/base 40

41. How to use BJT? 41 C B E Figure 16. BJT Model
junction-transistor-beginner-tutorial/
this-h-brigde-is-working
Figure 16. BJT Model
Figure 17. H-bridge with BJT 41

42. How to use MOSFET? Connect PMOS to Vcc, NMOS to ground 42 PMOS NMOS
Fo1f4&list=PLXrSeSVAb819HfhysOtYMdwD g3CTKXi6B
Figure 18. MOSFET Model
Figure 19. H-bridge with MOSFET
Connect PMOS to Vcc, NMOS to ground 42

43. Reference 43 DC Motor: Basic Principle:
Speed Control with PWM:
Shaft Encoder
manuals/forms/magnetic-encoder-guide.php
H Bridge
L298N Datasheet:
SN Datasheet: 43