Wireless Remote Motor Controller Sara Shahzad Joseph Owusu Masakatsu Suzuki TA:Scott Andrerson

1. Wireless Remote Motor ControllerSara ShahzadJoseph Owusu Masakatsu SuzukiTA:Scott Andrerson ECE 445 Spring 2006 Group #32

2. Introduction • Fundamental Power Electronics Knowledge • Suggested by Power Department • Learn RF Technology and go beyond the comfort zone • Interesting and challenging at the same time • Applications: Golf cart

3. Benefits and Features • Benefits • Inexpensive • Simple and efficient to use • Easy control • Features • Allows adjustable speed control • Motor will be able to run 150 W continuously and 250 W for at least one minute • Requires less power ( power from 12V lead acid battery) • Remote control capability

4. Design Specification • Input voltage of 12 Vdc • Output voltage ranging from 0 V to 12 Vdc, depending on the user specification. • Motor loads ranging up to continuous 150 W or 250 W for a minute. • Efficiency greater than 85%. • Current ripple ± 5%. • Voltage ripple less than ± 2%. • Wireless control in distances in excess of 300 ft.

5. Picture of the project

6. BLOCK DIAGRAM

7. Wireless remote controller(picture) Switch to turn on and off A/D converter Switch to Stop ad start Encoder potentiometer transmitter

8. Inputs • It is made up of two potentiometers (20k and 10k) • One was held at a constant value whereas the other was variable. • Set it to output (0V-3V) to control duty ratio

9. Encoder and A/D Converter and Transmitter • Adjusted Voltage reference for A/D is 3V • External clock with freq = 1/(1.1RC) =1/(1.1*10k*15pf) =606kHZ • Vin+ takes in analog voltage and converts it 6 bit parallel digital output. • Encoder encodes digital output and signal is fed to transmitter • Transmitter sends signals to Receiver at operating frequency of 902MHZ

10. Receiving circuit (picture) PWM transmitter D/A Decoder Gate Drive Inverter

11. Encoder and D/A (schematics) • The HT-648L decoder receives serial address and data from the encoder through RF module • SN74ALS04 inverts the data from HT-648 • DAC0808 receives data from HT-648 and outputs analog voltage with reference to Vref

12. PWM CONTROL and gate drive (schematics) RT= 20K CT=0.001uF

13. Waveforms from PWM Internal PWM comparator saw tooth pulse PWM output pulse (50% duty ratio)

14. Buck Converter

15. Converter choice and Implementation • Buck Converter versus Boost and Buck-Boost Converter. • According to the specifications, buck converter was ideal for our purposes. • Requires • An inductor • A capacitor • MOSFETS Buck Converter Configuration

16. Inductor Design The variables in the above equation were computed as follows: Hence, we computed our critical inductance to be 1.92uH. However, L>> Lcritical.

17. Inductor Design contd. • We chose ferrite core and using the parameters of the core, we determined the reluctance (Ř) to be 3.1078E6 H-1. • Using the magnetic flux as 1Tesla, we computed the maximum number of turns that we could wind around our inductor for our specific design. • L=N2/Ř= 234.6uH. • N was arbitrarily chosen to be 27 • Measured inductance ~257.1uH.

18. INDUCTOR (picture)

19. MOSFET IRL7833 Vdss=30V Rdson=3.8mΩ ID= 30A Diode MBR2545 Vf = 30V IF(AV) = 30A Rt = 12.3m Ω MOSFETS and Diode

20. H-bridge • Allows the bi-directional spin of the motor. • H-bridge chip (MC33883) feeds in signals into the gates of the 4 MOSFETS forming the H-bridge.

21. Schematic for H-bridge and Buck Converter

22. Testing Procedures • Output Voltage/Current • Output Power • Efficiency • Temperatures at various loads

23. A.) Efficiency versus Duty Ratio for varying loads

24. B.) Temperature (ºF) Versus Power

25. Challenges and Accomplishments • RF Technology • PWM distortion • Gate drive buffer • Capacitors in parallel • Analog Ground

26. RECOMMENDATIONS • Pick MOSFETS more carefully • Have an analog ground for the gate drive. • Diodes and MOSFETS in parallel to avoid power losses.

27. Credits • Prof. Jonathan Kimball • Prof. P. Scott Carney • Scott Anderson • Guoliang Zhang • Brett Nee

28. Thank you