BLDC block

BLDC block

Description

Simulates a brushless direct-current motor.

Parameters and ports

Parameters

• Inércia do sistema motor+carga: Inertia of the motor+load system. [Kg.m^2]
• Resistência por fase: Individual phase resistance. [Ohm]
• Indutância por fase: Individual phase inductance (minus the mutual inductance, if significant). [Henry]
• Número de pólos: Number of poles of the motor.
• Constante de torque: The motor's Torque constant. [N.m/A]
• Constante de força eletromotriz: The motor's Back-emf constant. [V.s]
• Constante de atrito viscoso: Viscous friction's constant.
• Força máxima de atrito estático: Determines the maximum static friction torque. [N.m]
• Força de atrito dinâmico: Determines the value of the dynamic friction torque. [N.m]
• Lookup table da back-emf fase a: A nx2 matrix which specifies the desired back-emf shape for the a phase of the motor. The first column of the matrix represents the angle in degrees (must start at 0, be monotonically incresing and end at 360); the second column is the value 'fa' for that angle, in the equation: 'ea = fa(theta)*Ke*Wm/2', where 'ea' is the back-emf in phase a, 'Ke' is the motor's Back-emf constant and 'Wm' is the motor's angular velocity.
• Lookup table da back-emf fase b: A nx2 matrix which specifies the desired back-emf shape for the b phase of the motor. The first column of the matrix represents the angle in degrees (must start at 0, be monotonically incresing and end at 360); the second column is the value 'fb' for that angle, in the equation: 'eb = fb(theta)*Ke*Wm/2', where 'eb' is the back-emf in phase b, 'Ke' is the motor's Back-emf constant and 'Wm' is the motor's angular velocity.
• Lookup table da back-emf fase c: A nx2 matrix which specifies the desired back-emf shape for the c phase of the motor. The first column of the matrix represents the angle in degrees (must start at 0, be monotonically incresing and end at 360); the second column is the value 'fc' for that angle, in the equation: 'ec = fc(theta)*Ke*Wm/2', where 'ec' is the back-emf in phase c, 'Ke' is the motor's Back-emf constant and 'Wm' is the motor's angular velocity.

Inputs

• Vab: Voltage between phases 'a' and 'b' of the motor. [Volts]
• Vbc: Voltage between phases 'b' and 'c' of the motor. [Volts]
• Tl: Load torque applied to the shaft of the motor. [N.m]

Outputs

• Theta_m: Angular position of the rotor [radians]
• w_m: Angular velocity of the rotor [radians/second]
• internal: Vector of other internal variables of the simulator:
  • Correntes: Vector [3x1] of the currents in all phases:
    • i_a: Current in phase a. [A]
    • i_b: Current in phase b. [A]
    • i_c: Current in phase c. [A]
  • Torques: Vector [3x1] of the torques created by all phases:
    • T_a: Torque due to phase a. [N.m]
    • T_b: Torque due to phase b. [N.m]
    • T_c: Torque due to phase c. [N.m]
  • FCEM: Vector [3x1] of the back-emfs in all phases:
    • e_a: Back-emf in phase a. [V]
    • e_b: Back-emf in phase b. [V]
    • e_c: Back-emf in phase c. [V]
  • Torque Total: Total torque, due to all phases together (T_a + T_b + T_c). [N.m]
  • Torque de atrito: Friction torque acting on the rotor due to Coulomb friction [N.m]

Examples

Example 1

This example demonstrates how to correctly display all of the BLDC's outputs.

Additional information

• Since the addition of Coulomb's friction (commit 46dd6e), this block does not support fixed-step solvers. If a fixed-step solver is chosen, undefined behavior may occur.

• The angle convention (where the rotor is located relative to the coils a, b and c when the angular position is zero) is implicitly defined by the back-emfs. If the default trapezoidal back-emf waveform is used (instead of a user-defined one), the angle convention is that when the angular position is zero, the rotor is perpendicular to the 'a' coil, with its south pole close to the 'b' coil).

• Example of a valid back-emf lookup table parameter: backemfa = [linspace(0,360,200)' sin(linspace(0,360,200)')];