1. High Performance Low Cost Low Lost Wireless DC Motor Speed Control
Jing Guo & Yu Qiao
TA: Jim Kolodziej
Professor: Paul Carney
Powerpoint Templates

2. Product Features
Wirelessly controlled
Five basic operations: start, stop, accelerate, decelerate, reset
90% efficiency with normal load
High tolerance in overload conditions
Low cost (under $12)

3. Main Components
Control signal generating logic
Wireless transceiver with encoder and decoder
Microcontroller for PWM generation and overload detection
Low side gate driver
Buck converter

4. Operation of the Product

5. Control Signal Generator
Five push buttons for five commands with a 3-input NAND gate
A 3-LED array is used to test the output of the circuit.
Commands
Codes
Start
110
Stop
111
Accelerate
100
Decelerate
010
Reset
001

6. Encoder & Decoder
Forward and backward parallel to serial transformation
Testing: Connect the signal generator, encoder and decoder in cascade and test if the output from LED is consistent.

7. Wireless Transmitter & Receiver
Operating frequency: 315 MHz
Serial data output from decoder directly feed into TX module
Digital modulate and send to antenna
RX module demodulates and amplifies the signal picked up by antenna
Serial data output to decoder

8. Testing
Test with 1kHz square wave from function generator (waveform got duplicated at RX end)
Test with the designed circuit (the LED array at RX gives correct combination)

9. Micro-controller Unit
MSP430G2152
PWM Generation
Feedback Unit

10. PWM Generation
MSP430G2152

11. Testing
Connect the Control Signal Generator to the selected input and the generated waveform has the correct the frequency and changes according to the command signals

12. Low Side Gate Driver
The low side gate driver take the PWM signal as its input and then boost the voltage to 10V
Testing: Connect the 3V PWM signal to the input and check if the output waveform has the same shape but swings between 0 and 10V

13. Buck Converter

14. Testing
Connect the PWM signal from the function generator to the gate of the MOSFET. Changing the duty ratio of the PWM will change the speed of the motor correspondingly.

15. Feedback Unit
Voltage Detector
Numerical Integral Approximation
Overload Signal Generation (detect signal and shut down signal)

16. Control Unit Structure

17. Numerical Integral Approximation
The average detect voltage over 100 time periods is over V_normal, then overload is detected.
If overload for time periods, output an OFF signal to PWM generator until the RESET signal is sent by the user

18. Overload Circuit Protection Function
Two frequency modes
High (160 kHz): for normal operation
Low (1.6 kHz): for overload protection
Note: Switching from Low to High requires RESET command from the user

19. Normal Load Setup

20. Normal Load Efficiency
Temperature
Around 34 ℃
Input Power = 12.1V *12.41A = W
Output Power = 10.4V * 14.0A = W
Efficiency = 145.6W /150.04W = 97%

21. 250W Overloading Setup

22. 250W Overloading without Protection
Temperature
Around 91 ℃
Input Power = 11.97V *21.3A = W
Output Power = 10.1V * 22.9A = W
Efficiency = W /254.96W = 90.7%

23. 250W Overloading with Protection
Temperature
Around 31 ℃
Input Power = 11.97V *21.5A = W
Output Power = 12.8V * 16.8A = W
Efficiency = W /257.35W = 83.5%

24. Cost
Total cost for the motor speed control parts = $10.602
Total cost for the wireless connection parts = $55.44
Total cost for the entire project = $66.442

25. Challenge
Properly detect and respond to overloading
Handle high current test cases (up to 50 A)
Cost limitation ($12 per unit)

26. Success
Transmitting and receiving control signals wirelessly
Successfully protecting the circuit by lowering frequency
Properly setup shut down point to protect the motor
Keeping the cost low

27. Future
Applications
- Shopping cart
- Golf bag carrier
Solid competitiveness on markets

28. Credits
Professor Philip T. Krein
Power lab administrator: Kevin James Colravy
TA: James Kolodziej