Abstract: The present disclosure provides a method and a device for controlling a power factor on motor side and a system having the same, and the method includes: controlling the motor using a control approach of Id?=0 so as to obtain quadrature-axis voltage Uq? and direct-axis voltage Ud? in a virtual coordinate system of a current control cycle; calculating a first control value according to Uq? and Ud?; obtaining a power factor control target value, and calculating a target control value according to the power factor control target value; performing a PI control on a difference between the target control value and the first control value so as to obtain a coordinate deviation angle, and overlapping the coordinate deviation angle to a motor angle of the current control cycle so as to build a virtual coordinate system of a next control cycle, such that the power factor on the motor side is controllable.

Abstract: The present disclosure provides a method and a device for controlling a power factor on motor side and a system having the same, and the method includes: controlling the motor using a control approach of Id?=0 so as to obtain quadrature-axis voltage Uq? and direct-axis voltage Ud? in a virtual coordinate system of a current control cycle; calculating a first control value according to Uq? and Ud?; obtaining a power factor control target value, and calculating a target control value according to the power factor control target value; performing a PI control on a difference between the target control value and the first control value so as to obtain a coordinate deviation angle, and overlapping the coordinate deviation angle to a motor angle of the current control cycle so as to build a virtual coordinate system of a next control cycle, such that the power factor on the motor side is controllable.

Abstract: A method for suppressing a speed fluctuation of a permanent magnet synchronous motor is provided in the present disclosure, including: obtaining a target speed ?_ref, a feedback speed, a fluctuation speed ??, a q-axis inductance Lq and a permanent magnet flux linkage ?f of the permanent magnet synchronous motor; performing a PI adjusting on ?? to obtain a q-axis reference current Iq_ref, and obtaining a q-axis target voltage U*q according to Iq_ref, ?_ref, ?? and ?f; performing a PI control on a q-axis actual voltage according to U*q to obtain a q-axis compensation current Iq_add; obtaining a d-axis target voltage U*d according to Iq_ref, Iq_add, ?_ref, ?? and Lq; performing a PI control on a d-axis actual voltage according to U*d to obtain a d-axis compensation current Id_add; superposing Iq_add and Iq_ref to perform a feedforward compensation on a q-axis current and superposing Id_add and the d-axis reference current to perform a feedforward compensation on a d-axis current.

Abstract: A method for suppressing a speed fluctuation of a permanent magnet synchronous motor is provided in the present disclosure, including: obtaining a target speed ?—ref, a feedback speed, a fluctuation speed ??, a q-axis inductance Lq and a permanent magnet flux linkage ?f of the permanent magnet synchronous motor; performing a PI adjusting on ?? to obtain a q-axis reference current Iq_ref, and obtaining a q-axis target voltage U*q according to Iq_ref, ?—ref, ?? and ?f; performing a PI control on a q-axis actual voltage according to U*q to obtain a q-axis compensation current Iq_add; obtaining a d-axis target voltage U*d according to Iq_ref, Iq_add, ?—ref, ?? and Lq; performing a PI control on a d-axis actual voltage according to U*d to obtain a d-axis compensation current Id_add; superposing Iq_add and Iq_ref to perform a feedforward compensation on a q-axis current and superposing Id_add and the d-axis reference current to perform a feedforward compensation on a d-axis current.