Method of identifying parameters of a motor system
A method of identifying parameters of a motor system having an electric motor and a control system for vibration reduction, includes: sweeping a frequency of an oscillating reactive torque injected into the motor, determining a natural frequency of the motor system, which is the frequency at which the reactive torque produces maximum amplitude of a vibration-related parameter obtained based on measurements, incrementally increasing a magnitude of reactive torque oscillating at the natural frequency, injected to the motor, obtaining a magnitude of the parameter for each magnitude of the reactive torque, and determining, for each magnitude of the reactive torque, a gain and a phase response of the motor system, the gain being based on the magnitude of the reactive torque and the corresponding magnitude of the parameter, and the phase response being based on a phase angle of the reactive torque and a phase angle of the corresponding parameter.
1 . A method of identifying parameters of a motor system comprising an electric motor assembly, and a control system, for vibration reduction in the electric motor assembly, the method comprising:
a) sweeping a frequency of an oscillating reactive torque injected into the electric motor,
b) determining a natural frequency of the motor system, the natural frequency being the frequency at which the oscillating reactive torque produces a maximum amplitude of a vibration-related parameter obtained based on vibration-related measurements by sensors mounted to the electrical motor,
c) incrementally increasing a magnitude of reactive torque oscillating at the natural frequency, injected to the electric motor,
d) obtaining a magnitude of the vibration-related parameter for each magnitude of the reactive torque injected in step c), and
e) determining, for each magnitude of the injected reactive torque, a gain, and a phase response of the motor system, the gain being determined based on the magnitude of the injected reactive torque and the corresponding magnitude of the vibration-related parameter, and the phase response being determined based on a phase angle of the injected reactive torque and a phase angle of the corresponding vibration-related parameter, and
f) controlling, by the control system, injected reactive torque based on the natural frequency, the gains, and the phase responses in a control scheme to reduce vibrations in the electric motor assembly.
2 . The method as claimed in claim 1 , wherein the oscillating reactive torque is injected at constant amplitude in step a).
3 . The method as claimed in claim 1 , wherein in step e) each gain is determined by a ratio between the magnitude of the vibration-related parameter and the magnitude of the injected reactive torque.
4 . The method as claimed in claim 1 , wherein in step e) each phase response is determined by a difference between the phase angle of the vibration-related parameter and the phase angle of the injected reactive torque.
5 . The method as claimed in claim 1 , wherein the—vibration-related parameter is one of vibrational velocity, acceleration, and displacement.
6 . The method as claimed in claim 5 , wherein the sensors are accelerometers, and the vibration-related parameter is vibrational velocity, and wherein the method includes converting the acceleration to vibrational velocity.
7 . The method as claimed in claim 1 , wherein the sensors measure horizontal acceleration.
8 . A non-transitory computer program comprising computer code stored on a non-transitory computer readable medium, the computer code when executed by a processing circuitry of a control system causes the control system to perform the steps of a method of identifying parameters of a motor system that includes an electric motor assembly, the method including:
a) sweeping a frequency of an oscillating reactive torque injected into the electric motor,
b) determining a natural frequency of the motor system, the natural frequency being the frequency at which the oscillating reactive torque produces a maximum amplitude of a vibration-related parameter obtained based on vibration-related measurements by sensors mounted to the electrical motor,
c) incrementally increasing a magnitude of reactive torque oscillating at the natural frequency, injected to the electric motor,
d) obtaining a magnitude of the vibration-related parameter for each magnitude of the reactive torque injected in step c),
e) determining, for each magnitude of the injected reactive torque, a gain, and a phase response of the motor system, the gain being determined based on the magnitude of the injected reactive torque and the corresponding magnitude of the vibration-related parameter, and the phase response being determined based on a phase angle of the injected reactive torque and a phase angle of the corresponding vibration-related parameter, and
f) controlling, by the control system, injected reactive torque based on the natural frequency, the gains, and the phase responses in a control scheme to reduce vibrations in the electric motor assembly.
9 . A control system comprising:
a storage medium including a computer code, and
processing circuitry configured to execute the computer code, causing the control system to perform a method of identifying parameters of a motor system that includes an electric motor assembly, the method including:
a) sweeping a frequency of an oscillating reactive torque injected into the electric motor,
b) determining a natural frequency of the motor system, the natural frequency being the frequency at which the oscillating reactive torque produces a maximum amplitude of a vibration-related parameter obtained based on vibration-related measurements by sensors mounted to the electrical motor,
c) incrementally increasing a magnitude of reactive torque oscillating at the natural frequency, injected to the electric motor,
d) obtaining a magnitude of the vibration-related parameter for each magnitude of the reactive torque injected in step c),
e) determining, for each magnitude of the injected reactive torque, a gain, and a phase response of the motor system, the gain being determined based on the magnitude of the injected reactive torque and the corresponding magnitude of the vibration-related parameter, and the phase response being determined based on a phase angle of the injected reactive torque and a phase angle of the corresponding vibration-related parameter, and
f) controlling, by the control system, injected reactive torque based on the natural frequency, the gains, and the phase responses in a control scheme to reduce vibrations in the electric motor assembly.
10 . A motor system comprising:
an electric motor assembly including an electric motor, and
a control system having:
a storage medium including a computer code, and
processing circuitry configured to execute the computer code, causing the control system to perform a method of identifying parameters of the motor system, the method including:
a) sweeping a frequency of an oscillating reactive torque injected into the electric motor,
b) determining a natural frequency of the motor system, the natural frequency being the frequency at which the oscillating reactive torque produces a maximum amplitude of a vibration-related parameter obtained based on vibration-related measurements by sensors mounted to the electrical motor,
c) incrementally increasing a magnitude of reactive torque oscillating at the natural frequency, injected to the electric motor,
d) obtaining a magnitude of the vibration-related parameter for each magnitude of the reactive torque injected in step c),
e) determining, for each magnitude of the injected reactive torque, a gain, and a phase response of the motor system, the gain being determined based on the magnitude of the injected reactive torque and the corresponding magnitude of the vibration-related parameter, and the phase response being determined based on a phase angle of the injected reactive torque and a phase angle of the corresponding vibration-related parameter, configured to control the electric motor, and
f) Controlling, by the control system, injected reactive torque based on the natural frequency, the gains, and the phase responses in a control scheme to reduce vibrations in the electric motor assembly.