UAE University College of Engineering Electrical Engineering Department Graduation Project II

1. UAE University College of Engineering Electrical Engineering Department Graduation Project II Implementation of a Real-Time Plant Controller Using TI Digital Signal Processor (DSP) Thursday, Jan 1st, 2004

2. Group Members Abdulqader Shaikh 960710521 Ayman Elkhidir 980211560 Mohammed Al Qawasmeh 980211579 Mohammed Mustafa 980211467 Mohammed Ismaeel Shekfa 980211484

3. Overview • Introduction • Summary • PWM • Space Vector PWM

4. Overview • Q15 • Open Loop Program • Budget Requirements • Gantt Chart • Conclusion

5. Introduction DMC1500 AC Induction Machine DSP Processor Constant V/Hz Principle Space Vector PWM Technique

6. 24V Feedback V/3 Changing Voltage Start Code Composer Software Feedback 110\220 V

7. Summary Main Study for the project: power electronics Transistor, diode, PWM, and Inverter Machine that give information about different types of motor DSP ( Digital Signal Processor)

8. Code Composer watch window, command window, programming window, and the graph window.

9. Open loop speed control for 3-phase AC induction motor: Implementation of PWM technique. • In order to create the required rotating MMF in the stator of an AC induction machine, the power inverter needs to be driven with the correct switching variable vector [a, b ,c] • Two major issues must be resolved. • Generation of revolving reference voltage vector Uout. • Determination of the switching pattern based on this reference voltage vector.

10. Generating the reference voltage vector: • Requires precise positioning of the reference voltage vector. • This implies accurately controlling the rotational speed ω, and magnitude of this vector, M. • The vector magnitude M controls the resultant peak line voltage which is supplied by the inverter.

12. 2. Realization of the switching pattern using PWM outputs: • For any position of V*, it must be transformed into the set of appropriate switching variables a, b and c. • Using the decomposed form of V*, appropriate compare values are calculated for use with C240 Event manager PWM generation unit.

13. Verification of space vector PWM algorithm • The correctness of the space vector PWM can be verified by filtering the PWM outputs of C240 using low pass filter and viewing the resultant signal on a scope.

14. Space Vector PWM Reference vector decomposition: • As the rotor of the motor rotates, the reference vector must rotate with it and this requires the sector to be changing since this vector will rotate 360 degrees with respect to the real (Alpha) axis. • Vector Ua is represented by switch state 1 • Vector Ub by switch state 2 • Null vector U0 by switch states 7 or 8. • Vector U* may be represented by averaging the amount of time spent in vectors a, b and 0 over a switching period.

15. Space Vector Sequence: • The SV sequence should assure that the load line voltages have the quarter wave symmetry to reduce even harmonics. • This is done by arranging the switching sequence in such a way that the transition from one to the next is performed by switching only one inverter leg at a time. • These conditions are met by the sequence Vz,Vn,Vn+1,Vz

16. Example: • Shows the waveform for each sector of a symmetric switching scheme. • Each PWM channel switches twice per every PWM period except when the duty cycle is 0% or 100%. • There is a fixed switching order among the three PWM channels for each sector. • Every PWM period starts and ends with O000. • The amount of O000 inserted is the same as that of O111 in each PWM period.

17. Software-Determined Switching SV PWM Pattern

18. Space Vector PWM Patterns • Software-determined toggling sequences • SV PWM hardware module

19. Space Vector PWM Patterns • Implementation of this switching scheme with TMS320C24x/F24x involves two steps: • Initialization of the compare units and selected GP Timer for symmetric PWM • Determination of the channel-toggling sequence based on the look-up table and the load of compare registers based on which sector ( s) Uout is in.

20. Limit Degree of Precision Q-Value Representation cost effective • DSP architectures are designed to handle finite number precision . • Q value is a fixed-point. And Great performance But

21. Q-Value • Programmers need to take into consideration: • Numerical operations should avoid overflow. • The fractional portion of the number should not be truncated. • Q-values are used whenever a fixed-point variable is used to store a floating-point value. • The Q-value specifies how many binary digits are allocated for the fractional portion of the number.

22. Q-Value • The Q15 is a popular format : • MSB is the sign bit. • Followed by 15 bits of fraction. • ‎In Decimal the range between (-1 and 0.9999) (8000H to 7FFFH)

23. Q-Value Where “h” is the decimal value “n” is the fraction position “b” is binary value 0 or 1.

24. Example Positive Number + Fractional portion: (2-1 + 2-2 = .75) The whole portion (22 = 4) The variable has a value 4.75 00010011 Using Q2 Result

25. Program

26. Start 1 Integrate speed to get phase THETA of Uout System configuration Configure and Start ADC Determine quadrant of Uout Set up GP Timers and Full Compare Units Obtain SIN (THETA) and COS (THETA) Calculate d-q components of Uout Initialize variables Reset flags Get decomposition matrix and calculate T1, T2, and T3 Clear INT flags Enable interrupt R Sampling period flag set? No Get output toggling sequence and load the compare registers Yes R Reset sampling period flag GP timer 2 INT service Read ADC data and re-start ADC Set sampling period flag Calculate set speed and voltage 1 Enable interrupt Return

27. Main program Signal generation V/Hz control ACI31_x1.ASM PWM generation RMP_CNTL.asm PWM calculation Speed period calculation VHz_prof.asm Svgen_mf.asm pwmodrv.asm Speed_pr.asm

28. ACI31_x1.ASM ain program

29. ACI31_x1.ASM This program implements a sampling loop to carry out all calculations. The PWM and sampling frequencies are independently controlled. Constant V/Hz principle is used to generate the magnitude of voltage command from frequency input. Space vector PWM technique is used to generate the PWM signals controlling a three phase voltage source power inverter so that desired voltage magnitude and frequency are applied to the phased of a AC induction motor.

30. RMP_CNTL.asm • The ramp function is the method to deliver the required value of frequency to the DMC1500. • Required input for speed period calculation. • Required input for Pulse Width Modulation.

31. RMP_CNTL.asm Computes the ramp function. Rmp_cntl.asm Setpt_value Target_value S_eq_t_flg

32. Task of the ramp function S_eq_t_flg

34. Volts / hertz control • Increasing Vs and fs by the same amount. • No Increasing in the magnetized current • High starting torque application • Low power consumption

35. From the equation : • Magnetic flux is increasing linearly with the decreasing in the frequency of the input stator voltage. • Magnetic flux will increase the magnetization current • Solution is by increasing the applied voltage in the stator linearly with the frequency.

36. Vhz_prof.asm Vhz_freq V_out VHz_prof.asm This module generates the output command voltage for a specific input command frequency according to specified volts/hertz profile. This is used for variable speed implementation of AC induction motor drives.

37. VHz_prof.asm

38. Speed Experiment

39. Excel Result

40. Visual Basic

41. Budget Requirements Offered Equipments DSP evaluation board 5520DHS DMC 1500 4416 DHS AC induction motor 736 DHS Total 10672DHS

42. Budget Requirements Needed Equipments Fuses 20 DHS Power Transistors 300 DHS Poster 100 DHS Total 420 DHS

44. Conclusion • DSP: TMS320C24xx • Power Controller: DMC1500 • Motor: AC Induction Motor • Task: Controlling the AC induction motor in real-time, implementing a TI DSP.