1. SynR Machine

This class encapsulates the information required to fully represent a synchronous reluctance machine.

1.1. Machine Background

Synchronous reluctance machines or SynRs are machines capable of creating electromagnetic torque without permanent magnets or a wound field located on the rotor. The primary aim of this machine class is to fully represent an actual SynR design. To do so, users are required to pass in information on key geometric dimensions such as rotor dimensions, machine parameters including number of pole pairs and machine ratings, the materials constituting the machine, and the stator winding layout and connection to an external drive.

1.2. Input from User

The information required to instantiate the SynR_Machine class has been split into four dictionaries. Each dictionary has been expounded upon below. It should be noted that if the dictionaries do not include the required keys, the SynR_Machine class will raise an error.

1.2.1. SynR Dimensions

The purpose of this dictionary is to fully define the geometrical dimensions of any SynR machine. This information is required by nearly all analyzers, be it structural, thermal, or electromagnetic, to evaluate SynR performance. The figure provided below represents a generic four pole, six slot SynR design. Relevant geometric dimensions have been labelled in this figure.

Users are not required to pass in each and every dimension shown in the above figure as this can result in an over-constrained geometry. The required keys for this input are provided below:

SynR Dimensions

Key	Description	Units
r_sh	Shaft radius	mm
r_ri	Inner rotor radius	mm
r_ro	Outer rotor radius	mm
d_r1	Length to first flux barrier	mm
d_r2	Length to second flux barrier	mm
d_r3	Length to third flux barrier	mm
r_f1	Radius of flux barrier bend	mm
r_f2	Radius of flux barrier bend	mm
r_f3	Radius of flux barrier bend	mm
w_b1	Width of first flux barrier	mm
w_b2	Width of second flux barrier	mm
w_b3	Width of third flux barrier	mm
l_b1	Length of first flux barrier arm	mm
l_b2	Length of second flux barrier arm	mm
l_b3	Length of third flux barrier arm	mm
l_b4	Length of first flux barrier span	mm
l_b5	Length of second flux barrier span	mm
l_b6	Length of third flux barrier span	mm
alpha_b	Flux barrier angle	degrees
alpha_st	Stator tooth angle	degrees
d_so	See stator figure	mm
w_st	Stator tooth width	mm
d_st	Stator tooth length	mm
d_sy	Stator yoke width	mm
alpha_so	See stator figure	degrees
d_sp	Stator shoe pole thickness	mm
r_si	Stator tooth radius	mm

The dimensions dictionary corresponding to the example design is:

SynR_dimensions = {
   'alpha_b': 135,
   'r_sh': 6,
   'r_ri': 6,
   'r_ro': 49,
   'r_f1': 0.1,
   'r_f2': 0.1,
   'r_f3': 0.1,
   'd_r1': 4,
   'd_r2': 8,
   'd_r3': 8,
   'w_b1': 4,
   'w_b2': 4,
   'w_b3': 4,
   'l_b1': 33.75,
   'l_b2': 24.4,
   'l_b3': 12.6,
   'l_b4': 13,
   'l_b5': 10,
   'l_b6': 7,
   'alpha_st': 25,
   'alpha_so': 12.5,
   'r_si': 50,
   'd_so': 5,
   'd_sp': 9,
   'd_st': 40,
   'd_sy': 36,
   'w_st': 12,
   'l_st': 100,
}

1.2.2. SynR Parameters

Apart from dimensions, knowledge of certain SynR parameters, such as number of slots, pole pairs, and rated conditions are required to define a SynR design. All such parameters are contained within this dictionary. This dictionary also includes the nameplate ratings of the machine such as the rater power, rated speed, etc. It is likely that users might not be aware of all parameters when they are evaluating a new SynR design (when running an optimization for example). In this case, dummy values can be passed in for the nameplate paramters and can be updated later after the evaluation process is complete using the SynR_Machine class’s clone method. The required key-value pairs for this input are provided below:

SynR Parameters

Key	Description	Units
p	Number of pole pairs
rated_speed	Rated speed of machine	rad/s
rated_power	Rated power of machine	W
rated_current	Rated coil current of machine	A
name	Identfier for machine

The parameters dictionary corresponding to the optimized design of the paper cited above is:

SynR_parameters = {
   'p': 2,
   'Q': 12,
   "name": "Example_SynR_Machine",
   'rated_speed': 1800,
   'rated_power': 3600,
   'rated_current': 10,
}

1.2.3. SynR Materials

This dictionary contains information on the materials making up the electric machine. This includes rotor and stator back iron material, retaining sleeve material etc. Presently, each value of this dictionary is another dictionary defining the key properties of the material. The key properties differs based on whether the material being defined is an electric steel, a permanent magnet, a retaining sleeve etc. Users are recommended to go through the materials folder within mach_eval to better understand the expected key-value pairs for this dictionary.

SynR Materials

Key	Description
air_mat	Material in the airgap of the machine. Impacts windage loss and rotor to stator heat transfer
rotor_iron_mat	Rotor back iron material
stator_iron_mat	Stator iron material
coil_mat	Coil material
shaft_mat	Rotor shaft material

The material dictionary corresponding to the example design is:

from mach_eval.machines.materials.electric_steels import (Arnon5)
from mach_eval.machines.materials.miscellaneous_materials import (
   Steel,
   Copper,
   Air,
)

SynR_materials = {
   "air_mat": Air,
   "rotor_iron_mat": Arnon5,
   "stator_iron_mat": Arnon5,
   "coil_mat": Copper,
   "shaft_mat": Steel,
}

1.2.4. SynR Winding

This dictionary contains information on the combined DPNV winding layout used in the SynR design. The winding_layout.py script file provided within the SynR folder defines certain popular DPNV winding layouts. The required key-value pairs for this input are provided below:

SynR Winding

Key	Description
no_of_layers	Number of winding layers. Most electric machines are have single or double layers.
layer_phases	List of phases corresponding to each slot
layer_polarity	List containing coil winding direction in each slot
pitch	Coil span
Z_q	Number of turns in each coil
Kov	Over winding factor for distributed windings
Kcu	Slot fill factor
coil_groups	Coil group information. Specific to DPNV windings
phase_current_offset	Offset of phase current

Further elaboration is required prior to providing the winding dictionary corresponding to the design discussed above. The winding layout of the example machine is shown below. This is a double layer, twelve slot winding with a coil span of 2. The blue lines correspond to phase U, red to phase V, and green to phase W coil sides. Solid and dotted lines are used to differentiate between the two winding layers. The numbers indicate the slot opening each coil side belongs to. Finally, arrows are used to indicate the direction in which current flows when a positive voltage is applied across the + and - terminals of each coil.

The winding dictionary corresponding to the layout shown above is:

SynR_winding = {
   "no_of_layers": 2,
   "layer_phases": [ ['U', 'V', 'W', 'U', 'V', 'W', 'U', 'V', 'W', 'U', 'V', 'W'],
                        ['V', 'W', 'U', 'V', 'W', 'U', 'V', 'W', 'U', 'V', 'W', 'U'] ],
   "layer_polarity": [ ['+', '-', '+', '-', '+', '-', '+', '-', '+', '-', '+', '-'],
                        ['-', '+', '-', '+', '-', '+', '-', '+', '-', '+', '-', '+'] ],
   "pitch": 2,
   "Z_q": 20,
   "Kov": 1.8,
   "Kcu": 0.5,
   "phase_current_offset": 0,
}

1.3. Creating a SynR_Machine object

Finally, the below Python code block shows how to create a SynR_Machine object using the dictionaries shown above. A walk-through on evalauting the electromagnetic performance of this machine is provided here.

from eMach.mach_eval.machines.SynR import SynR_Machine

ecce_2020_machine = SynR_Machine(
         SynR_dimensions, SynR_parameters, SynR_materials, SynR_winding
     )