double rotor switched reluctance motor

1. DOUBLE –ROTOR SWITCHED
RELUCTANCE MACHINE(DRSRM)
Guided by,
Mrs. Sofiya .A
Ass. Professor
EEE Dept.
Presented by,
Reshma Chandran
53, S7, EEE
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2. CONTENTS
Introduction
DRSM
Different configuration circuit for DRSRM
DRSRM as hybrid electric powertrain.
Design of DRSRM.
Simulation and Optimization of DRSRM.
Prototype of DRSRM.
Conclusion
Reference
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3. INTRODUCTION
 For a full hybrid electric vehicle, there are two electric machines,
which are independently operated as motor or generators.
 Paper presents a family of configurations of Double rotor
switched reluctance machine.
 The concept is potentially more compact, lower cost, and enables
two mechanical outputs suitable for hybrid electric transmissions.
 This integration also facilitates system level optimizations,
reduces the size and number of the machine components and
improves the overall transmission performance.
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4. DRSRM
 A new configuration of the switched reluctance machine that is
composed of two rotor and one stator within one machine
housing.
 Rotors can be independently operated and controlled; thus has
the full capability to output power and torque from independent
drive shafts.
 It is also possible to operate the two rotors simultaneously by
synchronizing electrically or mechanically.
 DRSRM can be operated as a torque coupler device such as
mechanical clutches in hybrid power train system.
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5. Different configurations exist for DRSRM
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6. DRSRM as hybrid electric vehicle
powertrain
 Typical full hybrid electric vehicle powertrain, two electric
machines are used
Motor: high torque to provide traction torque required at
output shaft.
Generator: high speed capacity since it is coupled with high
speed engines.
 DRSRM can be most applied, thus achieving a more integrated,
compact , potentially lower cost and reduce transmission
complexity .
 Torque capability α (machine air gap) 2, exterior rotor can be
designed for high torque (motor)and interior rotor designed for
high speed (generator).
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7. DESIGN OF THE DRSRM
A. Initial design for the Interior and Exterior SRM
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8. For prototype, interior SRM is defined to work at 0.5kW,2000r/min
and exterior SRM at 0.5kW,500r/min.
Flux density is chosen to be 1.8T.
Higher no: of rotor poles than stator poles for exterior SRM.
The criteria for pole angle design.
The minimum inductance criterion : SRM to have fully unaligned
position so that minimum inductance can be reached & thus max
torque .
Self starting criterion : the next phase rotor pole start to overlap
with next phase stator pole when currently excited rotor pole fully
enters the overlap position so that the SRM can start at any rotor
position.
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9. B. Integrated stator with flux barrier
Flux pattern with(a) and without(b) air gap
The difference between two
machines is flux barrier i.e., air gap
dividing the two stator.
The machine without air gap , flux
merges between both magnetic
circuits, adding unnecessary coupling
between two systems.
From the torque wave form, it can be
observed there exists a max 5% torque
variation for both machines.
The level of magnetic coupling
varies with load, speed, and rotor
direction.
Torque waveform: Exterior SRM
Torque waveform: Interior SRM
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10. An integrated stator structure is proposed
that mechanical rigidity of stator lamination, is
shown here.
The air gap in the middle of the stator
lamination is 1mm wide .
To maintain a single stator lamination, six
bridges are used to connect the both stator
lamination sections.
These narrow bridges
Are designed to saturate during
machine operation so majority flux can
be well separated.
Width(2mm) is thus chosen by
minimizing the leakage flux, and
maintaining mechanical strength .
Due to low saturation level under the stator
poles, clearance holes are placed.
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11. SIMULATION AND OPTIMIZATIONS OF
THE DRSRM
A. Electro magnetic simulation
* To study the machine performance and the influence of design
parameters.
* 2-D simulation have been carried out
* From EM simulation, the amplitude and frequency of flux
density can be analyzed.
B. Iron loss analysis
* Iron loss can be analyzed with EM simulation results
* Time variant magnetic flux density on each element can be
decomposed by forier analysis into different harmonic orders
* Total Fe loss per unit volume can be derived by summation of
all the frequency contribution.
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12. C. Thermal simulation
* Thermal contact resistance are defined between any two of
contacting parts.
* Boundary condition between machines surface and air , and
surrounding structures are set up by specifying the heat
transfer coefficient.
D. SRM drive simulation
* A machine and drive co simulation model is built in
MATLAB.
E. Turn on and Turn off angle optimization
* The optimization of turn-on and turn-off angles can be
studied based on the single pole excitation analysis (const.
current to a phase).
* SRM drive simulations are then utilized to optimize the
angles and reduce the torque ripple.
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13. F. Geometry optimization
* Pole angles have been varied to optimize the pole arc to pole
pitch angles of both the stator and rotor.
* Back iron thicknesses are selected to reduce the iron loss.
* Shapes of teeth are refined to minimize the torque ripple and
to increase slot area
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14. G. Load and Excitation Optimizations.
* The continuous thermal rating of the prototype is specified when
the interior and exterior rotor are at 2Nm,2000r/min and 8Nm,
500r/min.
* Taking initial Cu current densities 6A/mm2, electro magnetic design
are iterated in conjunction with the thermal model to ensure max
winding temperatures.
H. Stack length
* Smaller stack length results in lower Fe loss, hence efficiency.
* The stack length is smaller than 50mm, the required fill factor to
get the same rated torque is larger than 40% , which impractical in
manufacturing.
* Thus a 50mm stack length is an ideal selection
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15. I. Electromagnetic coupling analysis
* Electromagnetic field interactions between the laminations
and the stator clamps have been investigated via 3D
simulation.
* Shows the low flux concentration on interpoles stands, thus
do not interfere with the main magnetic field.
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16. PROTOTYPE OF DRSRM
 Two shafts were used to connect with each of the rotors within
one machine setup.
 Two shafts can be independently controlled so that various
operation modes can be achieved by DRSRM.
 The torque –speed chara of DRSRM were tested separately
Exterior rotor machine
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17.  Each output shafts was
connected to a brushed dc
dynamometer load machine.
The output performance
machines remained the same
whether they operated together or
separately.
DRSRM test rig
Assembled components
Cross section view of system
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18.  From the table primary design goal that the interior rotor
produces higher speed, while the exterior rotor produced four
times higher torque.
 Thus the proposed DRSRM to be a good candidate to suit the
speed and torque requirements of hybrid electric vehicle .
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19. CONCLUSION
 The DRSRM presented in this paper is a type SRM , composed of
double rotor and one stator in one machine housing.
 The detailed DRSRM design process is illustrated while novel flux
barrier designs are implemented to separate the flux paths
 The process of simulations and optimizations are discussed
 It has been proved that the two machines can be independently
controlled and operated over their relative torque–speed
envelopes.
 It is potentially more compact, lower cost, and get two mechanical
outputs, can be used to replace the two electric machines in hybrid
electric transmissions.
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20. REFERENCES
1. Yinye Yang , Nigel Schofield, and Ali Emadi, “Double – Rotor
Switched Reluctance Machine(DRSRM)” IEEE Transation on
Energy Conversion,Vol.30,No.2, June 2015.
2. C.V. Aravind, M. Nohisam, I. Aris, M.H. Marhabhan, D.
Ahammad, and M.Nirei, ”DRSRM: fundamentals and magnetic
circuit analysis”.
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21. THANK YOU
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