Biju Prasad B, VSSC ISRO
- Has developed fault tolerant EMA for isro
- ansys motor cad good for designing motors
- Common 4 aviation motors:
- magnix 65 - US, 200kg, 640kW, 3020 Nm, 3.2 kW/kg
- Siemens SP2 50 kg motor
- YASA 750R 37kg axial flux 250kW 200Nm torque 5kW/kg
- EMRAX 41 kg 380 kW, outlier power density, may be cheating
- Vita technologies make ISRO actuator
- 264 kN stall force, 64 kW power, 270V 110A in 4 coils, with quadruplex windings and quadruplex LVDT
- In BLDC, only 2 coils are used at a time
- Motor duty cycle for hansa
- 68kW for 30S
- 46kW for 16.5 mins
- 29 kW for 55 mins
- 4.1kW for 16.5mins
- 17kW for 30 S
- PMAC gives 6kW/kg power density, high cost, alll phases used together, sinusoidal commutation gives full utilisation, smooth torque, not like bldc
- Axial flux = 10 kW/kg, low inertial, torque is high, stacking of rotor stampings difficult
- radial flux = 3kW/kg high inertia, stator construction is simpler, stacking can be wire cut in edm
- motors have to satisfy rtca d0 160e qualification reqt for airborne equipment
Dr Karthick sitapaty, Vita technology
Sine drive is used for high speed motors
Bldc drive is used for simple Motors which are commonly used
Sine drive is used for machine tool spindles
In Sin drive LDL Q ratio is important
Bldc Motors can be converted to PM AC motor
Cobalt alloy tape material can take up to 2.5 Tesla
Normal Silicon Steel can take only up to 1.8 Tesla
When doing simulation for motors there should be at least three layers of cells in the air gap layer
This is important to get good torque calculation from the finite element model of the
Skew in the stamping reduces cogging torque in the Motors
AC drive has to be used with sine wave
Bldc drive cannot be used sine wave
AC drive gives 50% more are compared to bldc motor
For a radial flux motor torque is proportional to square of diameter
For an axial flux motor torque is proportional to cube of diameter
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
Stator is built using a tape of Cobalt alloy
Tape of Cobalt steel is wounded like a spool of tape
After winding, the slots are milled in the stator.
Magnet is fit for a trial purposes
Then the tape is unwounded
Then it is annealed through heat treatment
Then an adhesive layer is applied to the Cobalt alloy based tape
Then the tape is rolled back
The milled slots may not align again to insert the magnet due to the thickness of adhesive between the layers of the tape
This requires trial and error.
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