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

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Presentation on theme: "DC otor & H Bridge 1. Outline DC Motor Principle Speed Control H Bridge Control Power Figure 1. Real DC Motors 2."— Presentation transcript:

1 DC otor & H Bridge 1

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

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

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

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

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

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

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

9 Figure 7. H Bridge Diagram (http://en.wikipedia.org/wiki/H_bridge) Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) H Bridge 9

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

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

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

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

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

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

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

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

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 H Bridge’s Shape Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Figure 7. H Bridge Diagram (http://en.wikipedia.org/wiki/H_bridge) 21

22 Power Supply Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Figure 7. H Bridge Diagram (http://en.wikipedia.org/wiki/H_bridge) 22

23 Logic Power Supply Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Figure 7. H Bridge Diagram (http://en.wikipedia.org/wiki/H_bridge) 23

24 Inputs and Enable Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Figure 7. H Bridge Diagram (http://en.wikipedia.org/wiki/H_bridge) 24

25 M Outputs Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Figure 7. H Bridge Diagram (http://en.wikipedia.org/wiki/H_bridge) 25

26 M S1S3 S2 S Functions Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) 26

27 M S1S3 S2 S Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Functions Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) 27

28 v M S1S3 S2 S4 0 X X Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Functions Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) 28

29 M S1S3 S2 S Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Functions Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) 29

30 M S1S3 S2 S Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Functions Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) 30

31 M S1S3 S2 S4 Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Functions Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) 31

32 M S1S3 S2 S4 Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Functions Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) 32

33 M S1S3 S2 S4 Figure 9. L298N Block Diagram (Left Half) (L298N Datasheet) Functions Table 2. H Bridge Functions (http://en.wikipedia.org/wiki/H_bridge) 33

34 An example Figure mm DC Motor from Maxon motor-from-maxon/ Figure 11. SN Pin Connections (SN Datasheet) 40V GND /labsW14/lab6/index.html Figure 12. SmartFusion FPGA 34

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

36 Voltage Constraint (L298N) DC voltage cannot exceed H-bridge voltage constraint https://www.sparkfun.com/datasheets/Robotics/L298_H_Bridge.pdf Table 3. Voltage Constraint for L298N 36

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

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? this-h-brigde-is-working VS XrSeSVAb819HfhysOtYMdwDg3CTKXi6B MOSFET (Metal–Oxide–Semiconductor Field-Effect Transistor) Good for high current operation BJT (Bipolar Junction Transistor) Easier to build, use less circuitary Good for low current operation Figure 14. H-bridge with BJT Figure 15. H-bridge with MOSFET 39

40 What is BJT? What is MOSFET? NMOS – active high PMOS – active low PNP – active low NPN – active high Choose voltage/current wisely on gate/base Don’t need to know 40

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

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

43 Reference DC Motor: Basic Principle: Speed Control with PWM: Shaft Encoder https://www.anaheimautomation.com/ manuals/forms/magnetic-encoder-guide.php H Bridge L298N Datasheet: https://www.sparkfun.com/datasheets/Components/General/L298N.pdf SN Datasheet: 43


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