KR102553804B1 - Motor and control method for reducing overshoot of the motor - Google Patents

Abstract

The present invention relates to a control method for reducing overshoot of a motor capable of reducing an rpm overshoot that may occur in a motor when sensorless control of a motor in a rotating state by an external force such as driving wind. A starting signal reception step for receiving a signal, a rotation determination step for determining whether the rotor of the motor is rotating by an external force, a current for applying current to the D-axis or Q-axis of the motor according to whether the rotor is rotating. It is characterized in that it comprises an application step and a motor control step of sensorless controlling the motor.

Description

Motor and control method for reducing overshoot of the motor {Motor and control method for reducing overshoot of the motor}

The present invention relates to a control method for reducing overshoot of a motor capable of reducing rpm overshoot that may occur in a motor when a start signal is applied to sensorless control a motor in a rotating state by an external force such as driving wind. it's about

Motors are used in various devices, including vehicles, for cooling or other purposes. As an example of using a motor in a vehicle, there may be a motor connected to a cooling fan installed in the front of the vehicle, and the motor may be connected to a rotating shaft of the cooling fan to operate the cooling fan.

1 schematically illustrates the structure of a motor, particularly a BLDC motor. As shown in FIG. 1, the BLDC motor 10 has a stator 20 including a plurality of electromagnets 21a, 21b, and 21c in which a coil is wound around a core to continuously change a magnetic field, and installed around the stator 20 and a rotor 30 that rotates by receiving attractive and repulsive forces according to a changing magnetic field including a permanent magnet 31. As shown in FIG. 1, the electromagnets 21a, 21b, and 21c of the stator 20 may be composed of three phases including U, V, and W phases, respectively.

The magnetic fields generated from the electromagnets 21a, 21b, and 21c sequentially change with time to rotate the rotor 30. In more detail, alternating current is applied to each of the U, V, and W phases of the electromagnet to generate a sequentially changing magnetic field, and the rotor 30 rotates by receiving attractive and repulsive forces according to the magnetic field generated by the electromagnet.

The magnetic field generated from the stator 20 should be sequentially changed according to the rotational speed and position of the rotor 30, which is performed accurately to prevent malfunction of the motor and prevent noise and coking of the motor to improve efficiency. To do this, it is necessary to accurately detect the rotational speed and position of the rotor 30 .

As a method for detecting the rotational speed and position of the rotor 30, a sensor capable of detecting the position of the rotor, such as a Hall sensor, is installed around the rotor 30, or the stator ( A sensorless control method that controls the stator 20 by detecting the position of the rotor 30 using counter electromotive force generated in the coil of 20) is used, and a sensor capable of detecting the position of the rotor such as a Hall sensor and A sensorless control method may also be used in combination.

In order to apply the sensorless algorithm used in the sensorless control described above to motor control, a current of a certain size or more must be applied to the motor and the rotor of the motor must be rotating at a certain speed or more, which is called sensorless stabilization. . When sensorless stabilization is performed by applying a general starting signal to a motor in a stopped state, it is possible to apply a certain amount of current to the motor and rotate the motor's rotor at a certain speed or higher without any major problems. When a starting signal for the sensorless algorithm is applied while rotating by an external force, for example, a cooling fan installed toward the front of a vehicle in motion is rotating by driving wind, the rpm overshoot of the rotor occurs. As a result, there is a problem in that unnecessary noise may occur or performance degradation of the motor may occur.

Korean Patent Registration No. 10-1796948

The present invention has been made to solve the above problems, and the object of the overshoot reduction control method of the motor according to the present invention is that the start signal is not applied to the motor, but the rotor rotates by an external force such as driving wind. It is an object of the present invention to provide a control method for reducing overshoot of a motor that can prevent rpm overshoot from occurring even when a start signal is applied to the motor while performing sensorless control.

A motor overshoot reduction control method according to the present invention for solving the above problems includes a start signal receiving step of receiving a start signal of the motor, and determining whether the rotor of the motor is rotating by an external force. Step, a current applying step of applying current to a motor so that a magnetic field is formed in a direction in which the rotor does not rotate or rotates depending on whether the rotor rotates, and a motor control step of sensorless controlling the motor. to be characterized

In addition, the axis determination step of determining the D-axis and the Q-axis of the motor based on the position of the rotor detected by the rotor position sensor installed in the motor, which is performed before the current applying step, is further included, and the current applying step is performed. In the step of applying a current to the motor so that a magnetic field is generated in a direction in which the rotor does not rotate, the step of applying the current is a combination of randomly applied positional information and the position of the rotor detected by the rotor position sensor installed in the motor. and a sensorless control stabilization step of determining that the sensorless control has been stabilized when the error is within a certain range, wherein the sensorless control stabilization step determines the direction in which the rotor rotates when it is determined that the sensorless control has been stabilized. A current is applied to the motor so that a magnetic field is generated, and the current applying step applies a current to the motor so that a magnetic field is generated in a direction in which the rotor does not rotate when the rotor is rotating, and the rotor does not rotate. In this case, a current is applied to the motor so that a magnetic field is generated in a direction in which the rotor rotates, and the rotor is connected to a cooling fan installed in the vehicle and rotates when driving wind is generated.

A motor according to the present invention for solving the above problems is a stator in which a coil is wound, a rotor rotating by a magnetic field generated from the coil, a sensing means capable of detecting whether the rotor rotates, and the motor and an inverter reducing overshoot by supplying current to the coil through an overshoot reduction control method of

The cooling module according to the present invention for solving the above problems includes the motor, a fan rotating by the motor, and a fan shroud for accommodating the fan and cooling a heat exchange medium of a heat exchanger modularized together. .

According to the overshoot reduction control method of the motor according to the present invention as described above, even if a start signal is received while the rotor is rotating, a current is applied to the D-axis to generate a magnetic flux of a certain level or more to stabilize sensorless control. After the sensorless control is performed, there is an effect of preventing the occurrence of unnecessary noise by preventing the rpm overshoot of the motor rotor.

1 is a schematic diagram of a BLDC motor;
2 is a flowchart of a control method for reducing overshoot of a motor according to an embodiment of the present invention.
3 is a schematic diagram of a BLDC motor used in one embodiment of the present invention.
Figure 4 is a schematic diagram of a BLDC motor for explaining the D-axis and Q-axis of the motor.
5 is a graph of change in rpm when current is applied to the Q-axis and the D-axis while the rotor is rotating.

Hereinafter, a preferred embodiment of a control method for reducing overshoot of a motor according to the present invention will be described in detail with reference to the accompanying drawings.

First, the overshoot reduction control method of the motor according to the present invention can be applied to the BLDC motor described in the background of the present invention, and the BLDC motor rotates a device connected to the motor by an external force to rotate the motor. It may be a BLDC motor in a self-rotating state, or it may be a BLDC motor connected to a cooling fan that is installed toward the front of the vehicle and rotates by driving wind.

As shown in FIG. 1, the BLDC motor used in the present invention is electrically connected to the basic configuration of the BLDC motor, that is, a stator in which a coil is wound, a rotor rotating by a magnetic field generated from the coil, and a stator to generate a start signal to the stator and an inverter for applying current. In particular, such a motor can be applied to a cooling module. The cooling module includes a motor capable of reducing overshoot, a fan rotating by the motor, and a fan shroud for cooling the heat exchange medium of the modularized heat exchanger while accommodating the fan. can include

2 is a flowchart of a control method for reducing overshoot of a motor according to an embodiment of the present invention.

As shown in FIG. 2, the overshoot reduction control method of the motor of the present invention includes a start signal reception step (S10), rotation determination step (S20), current application step (S30), and motor control step (S40). can do.

The starting signal receiving step (S10) is a step of receiving a starting signal of a motor, and the starting signal of the motor may be transmitted from an inverter electrically connected to the motor.

The rotation determination step (S20) is a step of determining whether the rotor of the motor is rotating by an external force. Whether or not the rotor rotates can be determined using a means for detecting whether the rotation shaft connected to the rotor or a device connected to the rotation shaft is rotating, or a means for detecting rotation of the rotor itself disposed inside the motor. can One embodiment of the present invention can use the latter means, and as shown in FIG. 3, the Hall sensor 100 installed around the rotor 30 can be used as that means.

The hall sensor 100 is a transistor that detects a magnetic field, detects the direction, strength, and distribution of the magnetic field, and is installed around the rotor 30 to detect a change in the magnetic field, thereby detecting the current position and speed of the rotor 30. can detect However, the present invention does not limit the sensor for detecting the position of the rotor to the Hall sensor 100, and other equipment such as an encoder and a resolver may be used.

As shown in FIG. 3, at least one hall sensor 100 may be installed around the rotor 30, and if the polarity of the permanent magnets 31 included in the rotor 30 is a plurality of pairs, this Correspondingly, a plurality may be installed.

The current applying step (S30) is a step of applying the current to the D-axis or Q-axis of the motor according to whether the rotor 30 is rotating.

The D-axis and the Q-axis indicate the direction of the magnetic field generated from the stator 20 of the motor in a two-dimensional coordinate system, but are indicated by the D-axis component and the Q-axis component. In one embodiment of the present invention, the current application step (S30 ), but performed previously, may further include an axis determination step of determining the D-Q axis using the positional information of the rotor 30 detected by the rotor position sensor installed in the motor.

4 sequentially shows the rotor 30 in a rotating state to explain the D-axis and the Q-axis. As shown in FIG. 4A, the rotor 30 is in a state where the S pole of the permanent magnet 31 is directed upward and the N pole is directed downward. Even if a current is applied to the stator 20 and a magnetic field is generated, in order not to affect the rotation of the rotor 30 of the generated magnetic field, face the S pole of the permanent magnet 31 according to the rotational position of the rotor 30 The direction, that is, the magnetic field generated in the U phase should be the N pole, and the opposite direction of the U phase should be the S pole, and the direction of the U phase is called the D axis.

The D-axis is expressed as a fixed coordinate system fixed on a two-dimensional plane to express the magnetic field generated from the stator 20, but it can also be expressed as a rotational coordinate system. For example, as shown in FIGS. 4A and 4B, the axis determination step sets the D-axis in the same direction as the direction of the magnetic field of the rotor 30, but rotates the D-axis at the same angular velocity as the rotor 30. can be expressed as

Even though the inverter unit controls the current applied to the stator 20 so that the D-axis component occurs, the D-axis is the same as the direction of the magnetic field generated from the permanent magnet 31, so only the magnetic flux increases and decreases, and the torque of the rotor 30 increases. does not increase or decrease

The Q-axis is a component that increases or decreases the torque of the rotor 30, and can be set to an axis 90 degrees ahead of the D-axis, and can rotate at the same angular velocity as the rotor 30 as the D-axis.

In the current application step (S30), current is applied to the Q-axis so that the Q-axis component of the motor increases when the rotor 30 is not rotating, but when the rotor 30 is rotating by an external force, the D-axis is applied. Apply current to first. This is to prevent RPM overshoe of the rotor from occurring as described above.

For example, in relation to RPM overshoot, when a start signal is applied to the stator to rotate the rotor at 1000 rpm while the rotor is rotating at 1000 rpm by an external force (driving wind), as shown in FIG. A phenomenon in which the rpm of the rotor momentarily increases to about 1300 rpm may occur. This is called rpm overshoot, and when rpm overshoot occurs, unnecessary noise or performance degradation may occur. In the current applying step (S30) of the present invention, when the rotor 30 is rotating first, the current is first applied to the D-axis. is applied to generate a magnetic field to a certain extent or more to perform sensorless stabilization.

In order to generate only the D-axis component by applying current to the stator 20 in the current application step (S30), it is necessary to determine the position of the rotor 30 rotating by an external force. Position information of the rotor 30 may be used.

As shown in FIG. 2 , the current applying step ( S30 ) may include a sensorless control stabilization step ( S31 ) for determining whether or not sensorless stabilization is required.

In the sensorless control stabilization step (S31), as a method of determining whether the sensorless control is stabilized, the randomly applied position information of the rotor 30 and the position error of the rotor detected by the Hall sensor 100 installed in the motor are constant. If it is within the range, it can be determined that the sensorless control has been stabilized.

The randomly applied position information of the rotor 30 used in the sensorless control stabilization step (S31) may be position information of the rotor 30 estimated using counter electromotive force generated as the rotor 30 rotates. .

In the motor control step (S40), when it is determined that the sensorless control is stabilized in the sensorless control stabilization step (S31), the rotational speed of the rotor 30 can be controlled by generating a Q-axis component, and the motor control step ( In S40), the stator 20 can be controlled so that not only the Q-axis component but also the D-axis component is generated.

The present invention is not limited to the above embodiments, and the scope of application is diverse, and various modifications and implementations are possible without departing from the gist of the present invention claimed in the claims.

10: motor
20: stator
30: rotor
31: permanent magnet
100: hall sensor
S10: start signal reception step
S20: Rotation determination step
S30: current application step
S31: sensorless stabilization step
S40: motor control step

Claims (9)

A start signal reception step of receiving a start signal of the motor;
Rotation determination step of determining whether the rotor of the motor is rotating by an external force;
a current applying step of applying current to the motor so that a magnetic field is formed in a direction in which the rotor does not rotate or rotates according to whether the rotor rotates; and
a motor control step of sensorless controlling the motor;
Including,
In the current applying step, when the rotor is rotating, applying a current to the motor so that a magnetic field is generated in a direction in which the rotor does not rotate,
In the current applying step, when a current is applied to the motor so that a magnetic field is generated in a direction in which the rotor does not rotate, the current applying step includes the randomly applied position information and the rotor detected by the rotor position sensor installed in the motor. A control method for reducing overshoot of a motor, comprising a sensorless control stabilization step of determining that the sensorless control has been stabilized when the position error of is within a certain range.
According to claim 1,
Further comprising an axis determining step of determining the D axis and the Q axis of the motor based on the position of the rotor detected by the rotor position sensor installed in the motor, which is performed before the current applying step. Overshoot reduction control method.
delete According to claim 1,
In the sensorless control stabilization step, when it is determined that the sensorless control is stabilized, a current is applied to the motor so that a magnetic field is generated in a direction in which the rotor rotates.
According to claim 1,
In the current applying step, when the rotor does not rotate, an overshoot reduction control method of a motor, characterized in that for applying a current to the motor so that a magnetic field is generated in a direction in which the rotor rotates.
According to claim 1,
The overshoot reduction control method of the motor, characterized in that the rotor is connected to a cooling fan installed in the vehicle and rotates when driving wind is generated.
a stator in which a coil is wound;
a rotor rotating by the magnetic field generated by the coil;
a sensing means capable of sensing whether the rotor rotates; and
an inverter reducing overshoot by supplying current to the coil through the overshoot reduction control method of a motor disclosed in any one of claims 1, 2, and 4 to 6;
A motor comprising a.
The motor of claim 7;
a fan rotated by the motor; and
a fan shroud for accommodating the fan and cooling the heat exchanging medium of the modularized heat exchanger;
Cooling module comprising a. A start signal reception step of receiving a start signal of the motor;
Rotation determination step of determining whether the rotor of the motor is rotating by an external force;
a current applying step of applying current to the motor so that a magnetic field is formed in a direction in which the rotor does not rotate or rotates according to whether the rotor rotates; and
a motor control step of sensorless controlling the motor;
Including,
In the current applying step, when a current is applied to the motor so that a magnetic field is generated in a direction in which the rotor does not rotate, the current applying step includes the randomly applied position information and the rotor detected by the rotor position sensor installed in the motor. A control method for reducing overshoot of a motor, comprising a sensorless control stabilization step of determining that the sensorless control has been stabilized when the position error of is within a certain range.

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