KR20120051923A - Logic for reducing toque ripple of motor - Google Patents

Abstract

PURPOSE: Torque ripple reduction logic of a motor is provided to minimize a torque ripple component by compensating electrical angle of a rotor and inductance change for Q shaft current in the output of a PI controller. CONSTITUTION: A Q-shaft PI controller(PIq) recompenses error of a Q-shaft current. A first inductance compensator(13) recompenses Q-shaft inductance in a first Q-shaft control signal. A D-shaft PI controller(PId) recompenses error of a D-shaft current. A second inductance compensator(14) recompenses D-shaft inductance in a first D-shaft control signal. A first counter electro-motive force compensator(11) is electrically connected between the Q-shaft PI controller and the first inductance compensator. A second counter electro-motive force compensator is electrically connected between the D-shaft PI controller and the second inductance compensator.

Description

Logic for REDUCING TOQUE RIPPLE OF MOTOR

The present invention relates to a torque ripple reduction logic of a motor. More specifically, torque ripple of a motor capable of minimizing a torque ripple component by forward compensating a change in inductance of an electric angle and a Q-axis current of a rotor at the output of a PI controller. Relates to abatement logic.

In general, the controller that controls the driving of the motor is designed on the premise that the inductance of the motor is constant.

However, the arrangement of the permanent magnets of the motor and the arrangement of the windings of the motor is not constant and varies from position to position. Also, the inductance of the motor varies according to the electric angle. When the current applied to the motor is less than a certain current, magnetic saturation does not occur. Therefore, it is relatively large. When the current applied to the motor is above a certain current, Has a constant value close to a constant due to magnetic saturation. That is, the inductance of the motor is changed according to the electric angle and the current.

Therefore, when ignoring the change in inductance caused by the driving of the motor, torque ripple may occur due to the current change due to the change in inductance. This torque ripple causes the occurrence of current and torque ripple to increase further when the motor is driven by high current at high speed.

The present invention is to overcome the above-mentioned conventional problems, the object of the present invention is to compensate the inductance change for the electric angle and the Q-axis current to the output of the PI controller, the torque of the motor that can minimize the torque ripple component To provide ripple reduction logic.

In order to achieve the above object, the torque ripple reduction logic of the motor according to the present invention includes a Q-axis PI controller for compensating for an error in Q-axis current, and a first Q-axis for which error in Q-axis current is compensated for through the Q-axis PI controller. A first inductance compensator for compensating the Q-axis inductance to the control signal, a D-axis PI controller compensating for the error of the D-axis current, and a first D-axis control for compensating the error of the D-axis current compensated by the D-axis PI controller The signal may include a second inductance compensator that compensates for the D-axis inductance.

The second Q-axis control signal, which is electrically connected between the Q-axis PI controller and the first inductance compensator and compensates the counter electromotive force of the first Q-axis control signal compensated through the PI controller, is applied to the first inductance compensator. The apparatus may further include a first back EMF compensator.

Electrically connected between the D-axis PI controller and the second inductance compensator to apply a second D-axis control signal compensated for the back EMF of the first D-axis control signal compensated through the PI controller to the second inductance compensator. The apparatus may further include a second back EMF compensator.

The first inductance compensator may include a Q-axis control signal compensated for inductance and a D-axis control signal compensated for inductance in the second inductance compensator.

The torque ripple reduction logic of the motor according to the present invention is capable of minimizing the torque ripple component by forward compensating for the inductance change of the electric angle and the Q-axis current of the rotor at the output of the PI controller.

1 is a torque ripple reduction logic of a motor according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention. Here, parts having similar configurations and operations throughout the specification are denoted by the same reference numerals.

Referring to Figure 1, the torque ripple reduction logic of the motor according to an embodiment of the present invention is shown.

As shown in FIG. 1, the torque ripple reduction logic of the motor is configured to view and calculate the Q-axis and D-axis inductance of the motor as variables, and to forward-compensate the outputs of the PI controllers PIq and PId.

First, the PI controllers PIq and PId are fed back with currents Iqf and Idf sensed by the motor to the current controllers of the motor, and the calculated currents Iqa and Ida for controlling the motor to generate a desired output torque. Compare and compensate for any difference between the two currents, controlling the motor to produce the desired output torque.

The PI controllers (PIq, PId) is a Q-axis PI controller (PIq) for compensating and controlling the error of the Q-axis current of the motor and a D-axis PI controller (compensating and controlling the error of the D-axis current of the motor) PId).

In addition, the Q-axis PI controller PIq is electrically connected to the first back EMF compensator 11 and is generated in the winding of the motor to the first Q-axis control signal in which the error of the Q-axis current is compensated through the Q-axis PI controller PIq. The second Q-axis control signal that compensates for the Q-axis back electromotive force Iqce is output and applied to the first inductance compensator 13.

Here, the Q-axis counter electromotive force (Iqce) of the motor may be a product of the Q-axis linkage flux and the electric angular velocity (ω). That is, the first counter electromotive force compensator 11 compensates the counter electromotive force Iqce for the Q axis by adding the first Q-axis control signal multiplied by the Q-axis linkage flux and the electric angular velocity ω, thereby driving the motor at high speed. Increasing counter electromotive force can prevent damage to the motor and the drive components.

In addition, the D-axis PI controller (PId) is electrically connected to the second back EMF compensator 12, in the winding of the motor to the first D-axis control signal, the error of the D-axis current is compensated through the D-axis PI controller (PId) The second D-axis control signal compensated for the generated D-axis back EMF Idce is output and applied to the second inductance compensator 14.

Here, the D-axis counter electromotive force (Idce) of the motor may be a product of the D-axis linkage flux and the electric angular velocity (ω). That is, the second counter electromotive force compensator 12 compensates the D axis counter electromotive force (Idce) by adding the value obtained by multiplying the first D-axis control signal by the D-axis linkage flux and the electric angular velocity (ω). The counter electromotive force can prevent the motor and the driving components from being burned out.

In the motor control, when the inductance of the motor is assumed to be a constant, the Q-axis and D-axis voltages of the motor are expressed by Equation 1 below.

Where Vd is the D-axis voltage, R is the winding resistance, id is the D-axis current, L is the inductance, ω is the electrical angular velocity, Vq is the Q-axis voltage, iq is the Q-axis current, and φ is the magnetic flux of the permanent magnet.

The PI controllers PIq and PId apply the Q-axis and D-axis voltage expressions to control the driving of the motor so that the required D-axis and Q-axis currents are generated in the motor.

Unlike Equation 1, when the inductance of the motor is not a constant variable and the inductance is modeled as a function of electric angle and Q-axis current, the Q-axis and D-axis voltages of the motor are shown in Equation 2.

Where θ is the electrical angle. Subtracting Equation 1 from Equation 2, the remaining value is an inductance error value generated when the inductance is treated as a variable and when the inductance is treated as a constant. That is, the inductance error values for the Q axis and the D axis when the inductance is treated as a constant and when the variable is treated as shown in Equation (3).

The inductance error values Ld and Lq are functions modeled according to the electrical angle θ and the Q-axis current iq, and the electrical angles are due to the partial derivatives of the electrical angle and the Q-axis current iq. It has the form of a torque ripple having a periodicity for one revolution of.

Since the inductance error values Ld and Lq have a form in which the electric angular velocity of the rotor is multiplied, if the inductance error values Ld and Lq are compensated in the field weakening control region where the motor rotates at high speed, the motor It can compensate for torque ripple amplified at high speed. In the inductance error values Ld and Lq, partial differential values for electric angles and Q-axis currents are stored as reference values and can be calculated through interpolation.

The first inductance compensator 13 electrically connected to the first back EMF compensator 11 compensates the inductance error value Lq in the second Q-axis control signal output from the first back EMF compensator 11 to drive the motor. To control.

In addition, the second inductance compensator 14 electrically connected to the second counter electromotive force compensator 12 compensates for the inductance error value Ld in the second D-axis control signal output from the second counter electromotive force compensator 12, thereby driving the motor. To control.

That is, the first inductance compensator 13 and the second inductance compensator 14 forward-compensate torque ripple for inductance with respect to electric angles and Q-axis currents at the outputs of the PI controllers PIq and PId, thereby providing torque ripple components. It can be minimized.

What has been described above is just one embodiment for implementing the torque ripple reduction logic of the motor according to the present invention, and the present invention is not limited to the above embodiment, and as claimed in the following claims, the present invention Without departing from the gist of the present invention, those skilled in the art to which the present invention pertains to the technical spirit of the present invention to the extent that various modifications can be made.

PIq; Q axis PI controller PId; D-axis PI controller
11; A first back EMF compensator 12; Second back EMF compensator
13; A first inductance compensator 14; Second Inductance Compensator

Claims (4)

A Q-axis PI controller for compensating for errors in the Q-axis current;
A first inductance compensator for compensating the Q-axis inductance to the first Q-axis control signal whose error of the Q-axis current is compensated through the Q-axis PI controller;
A D-axis PI controller for compensating for errors in the D-axis current; And
And a second inductance compensator for compensating the D-axis inductance to the first D-axis control signal compensated for the error of the D-axis current compensated by the D-axis PI controller. The method according to claim 1,
The second Q-axis control signal, which is electrically connected between the Q-axis PI controller and the first inductance compensator and compensates the counter electromotive force of the first Q-axis control signal compensated through the PI controller, is applied to the first inductance compensator. Torque ripple reduction logic of the motor further comprising a first back EMF compensator. The method according to claim 1,
Electrically connected between the D-axis PI controller and the second inductance compensator to apply a second D-axis control signal compensated for the back EMF of the first D-axis control signal compensated through the PI controller to the second inductance compensator. Torque ripple reduction logic of the motor further comprising a second back EMF compensator. The method according to claim 1,
And a motor configured to receive and drive a Q-axis control signal compensated for inductance in the first inductance compensator and a D-axis control signal compensated for inductance in the second inductance compensator. .

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