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EECS 373 Presentation DC motor with H-bridge

EECS 373 Presentation DC motor with H-bridge. Team: Bowen Xu , Chenyu Yi, Yitian Chen. How to drive a motor. Two functions Rotate reversely by reverse the voltage (Appendix I) Speed increases with voltage applied LEGO 2838, without load:. M. -. +.

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EECS 373 Presentation DC motor with H-bridge

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  1. EECS 373 PresentationDC motor with H-bridge Team: Bowen Xu, Chenyu Yi, Yitian Chen

  2. How to drive a motor • Two functions • Rotate reversely by reverse the voltage (Appendix I) • Speed increases with voltage applied • LEGO 2838, without load: M - + http://www.philohome.com/motors/motorcomp.htm

  3. All in one – H bridge • Integrating the following functions: • Capable of driving the motor in both directions (Appendix II) • Control the speed (explain later) • What’s more? • Brake(Appendix III) • Free wheeling(Appendix IV)

  4. Control the speed using PWM • Can we use analog? • …Yes… But too complex • We prefer digital (Appendix V) • Can we connect PWM output pins on MCU with motor? • No! • The motor won’t move • Or magic smoke comes out! • PWM signal acts as “switch manager”(Appendix VI) • Manage big voltage source with small voltage source • Get different AVERAGE voltage with different duty cycle

  5. A safer way to manage the “switches” OUT1 R Vpwr M OUT2 PWM1 PWM2 R GND

  6. Forward OUT1 R Vpwr M 3.3V OUT2 GND 1 0 0V PWM1 Vavg GND PWM2 0 1 3.3V Vavg 0V R GND

  7. Reverse GND OUT1 R Vpwr M 3.3V OUT2 0 1 0V PWM1 Vavg GND PWM2 1 0 3.3V Vavg 0V R GND 7 7

  8. Brake 1 GND OUT1 R Vpwr M OUT2 GND 0 0 PWM1 GND GND PWM2 1 1 3.3V 3.3V 0V 0V R GND 8

  9. Brake 2 Vpwr OUT1 R Vpwr M 3.3V 3.3V OUT2 Vpwr 1 1 0V 0V PWM1 Vpwr Vpwr PWM2 0 0 R GND 9 9

  10. Add one more function: ENABLE OUT1 Vpwr M OUT2 PWM1 PWM2 EN R GND

  11. Our Basic H-bridge Chip 1 2 3 4 5 Vpwr 6 7 OUT1 PWM1 PWM2 OUT2 ENABLE GND

  12. An example of using data sheet learn to use mc33886

  13. Before we start • Scenario • Use RS-540 to drive a model car • The rated voltage: 7.2V • Current for normal speed: 3A • 2 Problems • Is MC33886 capable? • Bear 7.2V? • Supply sufficient current? • How to connect the pins

  14. For problem 1: Properties of MC33886 • Output voltage and current: • Vpwr: 5 to 12V • Max current: 5.2A • Other information • PWM input frequency no higher than 10kHz

  15. For problem 2: Pin descriptions Vpwr 1 2 3 4 5 6 7 OUT1 PWM1 PWM2 OUT2 ENABLE GND General Chip we have MC33886 (get from data sheet)

  16. Connect MC33886 with MCU and motor 7.2V MCU Vpwr OUT1 PWM1 IN1 PWM2 IN2 RS-540 D1 D2 0 1 FS OUT2 Ccp GND 30nF

  17. 7.2V 5.2A 10.4A 5.2A 0 1 MCU Vpwr Vpwr OUT1 OUT1 PWM1 IN1 IN1 PWM2 IN2 IN2 RS-540 D1 D1 D2 D2 Dual H-bridge to get greater power! FS FS OUT2 OUT2 Ccp Ccp 6.03 dollar each (www.findchips.com) GND GND

  18. Questions?

  19. Back Appendix IForward and reverse M M - + + - - + - + + - - +

  20. Back Appendix IIForward and reverse with simple H-bridge sw1 sw3 + M + - + - - + - sw2 sw4

  21. Back Appendix IIIBrake with simple H-bridge sw1 sw3 + M + + GND GND - + - sw2 sw4

  22. Back Appendix IIIBrake with simple H-bridge sw1 sw3 + M + - - + - sw2 sw4

  23. Back Appendix IIIBrake with simple H-bridge sw1 sw3 + M + + - + - sw2 sw4

  24. Back Appendix IVFree wheeling

  25. Back Appendix V PWM and Vavg Vavg = Vpeak * Duty_cycle 3.3V 0V

  26. Back Appendix VIOutput voltage with PWM control Vpwr = 12V Duty cycle: 30% 12V Vout 3.3V 3.6V

  27. Back Appendix VIIMC33886 Data sheet: http://www.freescale.com/files/analog/doc/data_sheet/MC33886.pdf

  28. Back Appendix VIIIMC33886 Data sheet, pin descriptions http://www.freescale.com/files/analog/doc/data_sheet/MC33886.pdf

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