6.18. Motor selection (student version)

Written by Marc Budinger (INSA Toulouse), Scott Delbecq (ISAE-SUPAERO) and Félix Pollet (ISAE-SUPAERO), Toulouse, France.

6.18.1. Design graph

The following diagram represents the design graph of the motor’s selection. The mean speed/thrust (Ωmoy & Tmoy), the max speed/thrust (Ωmax & Tmax) and the battery voltage are assumed to be known here.

Fig. 6.21 Motor design graph

6.18.1.1. Sizing code and optimization

Exercise 6.17

Propose a sizing code for the motor

# Specifications

# Reference parameters for scaling laws
# Motor reference
# Ref : AXI 5325/16 GOLD LINE
T_nom_mot_ref = 2.32  # [N.m] rated torque
T_max_mot_ref = 85.0 / 70.0 * T_nom_mot_ref  # [N.m] max torque
R_mot_ref = 0.03  # [Ohm] resistance
M_mot_ref = 0.575  # [kg] mass
K_T_ref = 0.03  # [N.m/A] torque coefficient
T_mot_fr_ref = 0.03  # [N.m] friction torque (zero load, nominal speed)

# Assumptions
T_pro_to = 0.5  # [N.m] Propeller Torque during takeoff
P_pro_to = 100  # [W] Propeller Power during takeoff
Omega_pro_to = 400.0  # [rad/s] Propeller speed during takeoff
T_pro_hov = 1.0  # [N.m] Propeller Torque during hover
P_pro_hov = 50  # [W] Propeller Power during hover
Omega_pro_hov = 0.22  # [rad/s] Propeller speed during hover
U_bat_est = 14.0  # [V] Battery voltage value (estimation)

# Design variables

## To be completed

# Equations

## To be completed

%whos

Variable        Type     Data/Info
----------------------------------
K_T_ref         float    0.03
M_mot_ref       float    0.575
Omega_pro_hov   float    0.22
Omega_pro_to    float    400.0
P_pro_hov       int      50
P_pro_to        int      100
R_mot_ref       float    0.03
T_max_mot_ref   float    2.8171428571428567
T_mot_fr_ref    float    0.03
T_nom_mot_ref   float    2.32
T_pro_hov       float    1.0
T_pro_to        float    0.5
U_bat_est       float    14.0