Notes Day 1 National workshop on electric aircraft and allied technologies - 4

 Biju Prasad B, VSSC ISRO

1. Has developed fault tolerant EMA for isro
2. ansys motor cad good for designing motors
3. Common 4 aviation motors:
1. magnix 65 - US, 200kg, 640kW, 3020 Nm, 3.2 kW/kg
2. Siemens SP2 50 kg motor
3. YASA 750R 37kg axial flux 250kW 200Nm torque 5kW/kg
4. EMRAX 41 kg 380 kW, outlier power density, may be cheating
4. Vita technologies make ISRO actuator
5. 264 kN  stall force, 64 kW power, 270V 110A in 4 coils, with quadruplex windings and quadruplex LVDT
6. In BLDC, only 2 coils are used at a time
7. Motor duty cycle for hansa
1. 68kW for 30S
2. 46kW for 16.5 mins
3. 29 kW for 55 mins
4. 4.1kW for 16.5mins
5. 17kW for 30 S
8. PMAC gives 6kW/kg power density, high cost, alll phases used together, sinusoidal commutation gives full utilisation, smooth torque, not like bldc
9. Axial flux = 10 kW/kg, low inertial, torque is high, stacking of rotor stampings difficult
10. radial flux = 3kW/kg high inertia, stator construction is simpler, stacking can be wire cut in edm
11. motors have to satisfy rtca d0 160e qualification reqt for airborne equipment
    

Dr Karthick sitapaty, Vita technology 

1. Sine drive is used for high speed motors

2. Bldc drive is used for simple Motors which are commonly used 

3. Sine drive is used for machine tool spindles 

4. In Sin drive LDL Q ratio is important 

5. Bldc Motors can be converted to PM AC motor 

6. Cobalt alloy tape material can take up to 2.5 Tesla 

7. Normal Silicon Steel can take only up to 1.8 Tesla 

8. When doing simulation for motors there should be at least three layers of cells in the air gap layer 

9. This is important to get good torque calculation from the finite element model of the 

10. Skew in the stamping reduces cogging torque in the Motors

11.  AC drive has to be used with sine wave 

12. Bldc drive cannot be used sine wave 

13. AC drive gives 50% more are compared to bldc motor 

14. For a radial flux motor torque is proportional to square of diameter 

15. For an axial flux motor torque is proportional to cube of diameter

16.  2 stator 2  Rotor model will decrease the load on the bearing, as only the differential load comes to the bearing. This is a novel concept being explored by ISRO and Vita Technologies 

17. 
    

18. Stator is built using a tape of Cobalt alloy 

19. Tape of Cobalt steel is wounded like a spool of tape

20. After winding, the slots are milled in the stator. 

21. Magnet is fit for a trial purposes

22. Then the tape is unwounded

23. Then it is annealed through heat treatment

24. Then an adhesive layer is applied to the Cobalt alloy based tape 

25. Then the tape is rolled back 

26. The milled slots may not align again to insert the magnet due to the thickness of adhesive between the layers of the tape 

27. This requires trial and error.