KR100804429B1 - Field weakening control method and apparatus using voltage in driving motor of automotive steering system - Google Patents

Abstract

An apparatus and a method for controlling a field weakening are provided to reduce load applied to a CPU and increase speed required for performing the field weakening control by performing the field weakening control only when input or output voltage is above a predetermine critical value without using a motor location sensor. A method for controlling a field weakening comprises the step of detecting an input voltage or an output voltage of a driving motor(S210). It is determined if the determined voltage exceeds a predetermined critical voltage(S220). If the voltage of the driving motor exceeds the critical voltage, reverse magnetic flux is increased(S230). The reverse magnetic flux has a direction opposite to that of induced magnetic flux that induces reverse electromotive force which is generated from the driving motor.

Description

Field Weakening Control Method and Apparatus Using Voltage in Driving Motor of Automotive Steering System}

1 is a block diagram of a field weakening controller according to a preferred embodiment of the present invention;

2 is a flowchart of a field weakening control method according to a preferred embodiment of the present invention;

3 is an internal perspective view of a steering apparatus driving motor to which field weakening control according to the present invention is applied;

4 is a magnetic flux distribution diagram in the field weakening control according to the present invention.

<Description of Symbols for Main Parts of Drawings>

100: weak field controller 110: detection unit

120: control unit 130: execution unit

150: (drive) motor

The present invention relates to a field weakening controller and method for a vehicle steering device driving motor using a voltage. More particularly, the present invention relates to a weak field control method for controlling the reverse magnetic flux to increase in proportion to the input / output voltage rising above the threshold voltage by setting the threshold voltage in advance without the need for expensive equipment installation and complicated calculation.

Steering system of the vehicle (Steering System) is a device for the driver to freely change the driving direction of the vehicle by turning the steering wheel. Therefore, the steering system is closely related to the front axle or the front wheel alignment, and it is a very important device for driving safety together with the brake system. In general, the steering system should be small so as to have a turning radius, the vehicle's turning should be stable at high speeds, and the steering operation should be light and free.

As automobiles become more advanced, low-pressure tires are used, and the ground resistance of the front wheels increases due to the automation of large vehicles, and the steering wheel is required to operate, and the power assisted steering assists the steering wheel's operation by installing a power source in the steering system. A device (Power Steering Appratus) has been developed.

Generally, as a power assist steering device of a vehicle, a hydraulic power steering steering system using hydraulic pressure of a hydraulic pump has been used, but since the 1990s, an electric power steering steering system using an electric motor has been used. It is becoming more and more common.

Referring to the operation principle of the electric power assisted steering device, the motor control current is calculated by the electronic controller and the current value flowing through the motor is detected from the torque of the steering wheel, the speed of the vehicle, and the steering angle detected by the sensor. The motor control current is compared with the current of the actual motor, and the difference is transmitted to the motor to drive the motor to assist the driver in steering. As the driver applies torque to the steering wheel, the current delivered to the motor increases to assist the driver's steering operation.

On the other hand, the motor is composed of a stator (rotor) and a rotor (stator) and when the current flows to the rotor to form a magnetic flux has a principle that the rotor rotates by the interaction of the magnetic flux and the rotor magnetic flux. Such a motor, on the contrary, causes a change in magnetic flux when the rotor rotates, and this amount of change in magnetic flux generates induced electromotive force in the coil of the stator, and this mechanism is used for the generator.

Therefore, the induced electromotive force generated when the motor rotates is generated in a direction that hinders the rotation of the rotor, which is called a reverse electromotive force (逆 起 電力). Since the counter electromotive force is proportional to the time variation of the rotor rotation, the amount of occurrence of the counter electromotive force is small when the motor rotates at a low speed, and thus does not significantly affect the motor control. It grows in proportion.

The counter electromotive force generated in this way may cause a problem in motor control performed in the electronic control apparatus. That is, when a constant voltage / current is applied, a motor speed or output (torque) corresponding to the voltage / current can be obtained at a low speed, but at a high speed, a back electromotive force is largely generated, so the motor speed or output predicted from the input voltage / current is obtained. You will not be able to get this, and you will have to change the input voltage / current to get the desired motor speed or output. At this time, a current / voltage is applied to generate the reverse magnetic flux in a direction opposite to the magnetic flux that generates the counter electromotive force, and this is called field weakening control.

Looking at the principle of the field weakening control, since the counter electromotive force generated in the motor increases in proportion to the rotation speed of the motor, it is opposite to the magnetic flux in which the counter electromotive force is generated when the rotation speed of the motor is measured or calculated or more than the preset rotation speed. Adjust the input current / voltage so that the reverse flux in the direction of increase is increased. In the conventional weak field control method, information about the position of the motor is required to know the rotational speed of the motor, and an expensive sensor is needed to detect the position of the motor.

In addition, the process of calculating the rotational speed of the motor by using the position information of the motor is complicated, causing a problem of increasing the amount of calculation.

In order to solve this problem, the present invention provides a method for increasing the reverse magnetic flux in a direction to attenuate counter electromotive force when the input or output voltage rises above the threshold voltage by setting the threshold voltage in advance without the need for expensive equipment and complicated calculations. The main purpose is to provide a field control method.

In order to achieve the above object, the present invention provides a field weakening control method using a field weakening control device for a driving motor of an automobile steering field, the field weakening control device comprising the steps of: (a) sensing the input or output voltage of the motor; (B) determining whether the sensed current motor voltage is equal to or greater than a predetermined threshold voltage, and (c) inducing to induce counter electromotive force generated in the drive motor only when the current motor voltage is greater than or equal to the threshold voltage. And controlling to increase the reverse magnetic flux in a direction opposite to the magnetic flux.

In addition, the field weakening control device of the vehicle steering apparatus driving motor according to the present invention, the sensing unit for periodically deducting the input voltage or output voltage of the drive motor and transmitting it to the control unit, and the input voltage or After determining whether the output voltage is greater than or equal to the predetermined threshold voltage, the controller generates a reverse flux generation signal and transmits it to the execution unit only when the output voltage is greater than or equal to the threshold voltage, receives a command signal from the controller, and generates counter electromotive force. It comprises a performing unit for controlling the amount of current applied to the coil provided in the at least one stator (Stator) provided in the motor so that the reverse magnetic flux is formed in the direction opposite to the induction magnetic flux.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

1 is a block diagram of a field weakening controller according to a preferred embodiment of the present invention.

The field weakening controller 100 controls the counter electromotive force due to the rotation of the motor 150 by measuring the input or output voltage of the motor 150 in the vehicle steering apparatus and adjusting the reverse magnetic flux based thereon. The field weakening controller 100 according to the preferred embodiment of the present invention includes a detector 110, a controller 120, and a performer 130.

The detector 110 detects an input voltage or an output voltage of the motor 150 periodically and transmits the same to the controller.

The controller 120 determines whether the input voltage or the output voltage of the motor 150 transmitted from the detector is greater than or equal to a preset threshold voltage, and controls the execution unit 130 only when the threshold voltage is greater than or equal to the reverse magnetic flux. Create a.

At this time, the control unit preferably generates a command signal for generating a reverse magnetic flux in proportion to the current motor voltage (input or output) and transmits to the execution unit.

In some cases, the difference between the current motor voltage and the threshold voltage may be calculated, and a reverse magnetic flux proportional thereto may be generated.

The execution unit 130 receives the reverse magnetic flux generation command signal from the controller and controls an amount of current applied to the coil provided in the one or more stators provided in the motor, so as to be opposite to the induced magnetic flux generating the counter electromotive force. Control the back magnetic flux to be formed. This reverse flux control method will be described in detail with reference to FIG. 3 below.

As used herein, the term "reverse flux" refers to a magnetic flux in a direction opposite to the induced magnetic flux caused by the rotation of the rotor which induces counter electromotive force, and means a magnetic flux whose magnitude is controlled by differently adjusting the amount of current flowing in at least one stator coil of the motor. do.

At this time, the difference between the current motor voltage (Vc) or the threshold voltage (Vt) (Vc-Vt) and the generated inverse magnetic flux (Ψr) to form a proportional relationship, the specific proportional relationship is represented by the following equations 1 to 3 It can be determined by one or more of.

Where k is a proportional constant and n can be determined as an integer or rational number as an integer.

The relationship between the current motor voltage and the reverse magnetic flux may be appropriately changed according to the motor control sensitivity of the vehicle steering apparatus, the relationship between the torque and the motor speed, the current speed of the vehicle, the amount of steering angle change per hour, and the type of vehicle.

In the present invention, the current motor voltage Vc is preferably the current input voltage of the motor, but in some cases, the current motor voltage Vc may be controlled based on the output voltage of the motor.

2 is a flowchart of a field weakening control method according to a preferred embodiment of the present invention.

First, the sensing unit 110 of the field weakening controller 100 detects an input or output voltage of the motor 150 of the vehicle steering apparatus and transmits the detected voltage to the control unit (S210). The controller determines whether the detected input or output voltage of the motor 150 is equal to or greater than a preset threshold voltage (S220). When it is determined that the input or output voltage of the motor 150 is greater than or equal to the threshold voltage, a command signal for generating reverse magnetic flux is generated and transmitted to the execution unit (S230). The performing unit controls the amount of current applied to the coil of the motor stator to generate reverse magnetic flux (S230).

3 is an internal perspective view of a motor to which the field weakening control method according to the present invention is applied, and FIG. 4 is a magnetic flux distribution diagram in the field weakening control according to the present invention.

As shown in FIG. 3, the motor to which the present invention is applied is a three-phase motor in which a rotor 310 of a permanent magnet is disposed in the center and three stators 320, 321, and 322 are disposed at equal intervals of 120 degrees around the motor. . Coil 330 is wound around each stator, and a current is applied to the coil independently to rotate the rotor by the interlocking of the magnetic flux generated therein and the magnetic flux of the rotor. The magnetic flux generated in each stator has a direction perpendicular to the coil and is proportional to the amount of current and the amount of winding of the coil. In addition, the total magnetic flux is determined by the vector sum of the three-way magnetic flux generated in each stator.

Figure 4 shows the relationship between the magnetic flux in the process of the field weakening control according to the present invention, Φ r is the basic magnetic flux of the rotor, Φ i means the induced magnetic flux by the rotation of the rotor to induce the counter electromotive force The total magnetic flux generated by the rotor rotation is determined by the simple sum of these two components. Is the total vector sum of the magnetic flux generated by the current applied to the three stators.

Normally, only components perpendicular to the total magnetic flux? T of the rotor among the magnetic flux? S generated by the stator generate the torque of the motor, that is, the motor output.

As shown in FIG. 4A, when the rotor rotates at a low speed, since the magnitude of the induced magnetic flux Φ i that generates counter electromotive force is small, the magnetic flux Φ s generated by the stator is in a direction perpendicular to the basic magnetic flux Φ r of the rotor. Apply the current to maximize the output of the motor.

However, when the rotor rotates at a high speed, as shown in FIG. 4B, the magnitude of the induced magnetic flux generating the counter electromotive force increases to cancel the applied current component, so that the speed and output of the motor become smaller than expected, and in this case, proper motor control It becomes impossible.

Under these conditions, the field weakening control according to the present invention is carried out, and as shown in FIG. 4C, by controlling the amount of current applied to the stator, a component in a direction opposite to the induced magnetic flux of the rotor among the magnetic fluxes generated by the three stators, In other words, the reverse magnetic flux (ψr) is generated. That is, the vector sum of the total magnetic flux by the stator has a constant angle with the direction perpendicular to the total magnetic flux of the rotor, so that the amount of current applied to each of the stators is appropriately controlled so that the reverse magnetic flux (ψr) according to the present invention is generated. It is.

In this way, by substantially canceling the induced magnetic flux that generates the counter electromotive force, the same motor control as in the low speed rotation of the motor becomes possible.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, according to the present invention, after the input or output voltage of the motor is measured, the field weakening control is performed only when it is larger than the preset threshold voltage, thereby performing the field weakening control by calculating the conventional motor rotational speed. Compared with this, there is no need to use an expensive motor position sensor, and there is an effect of reducing the load on the CPU according to the motor speed calculation and improving the speed of control.

Claims (4)

A field weakening control method using a field weakening control device for an automobile steering device driving motor, wherein the field weakening control device includes: (a) sensing the input or output voltage of the motor; (b) determining whether the sensed current motor voltage is greater than or equal to a preset threshold voltage; And (c) controlling to increase a reverse magnetic flux in a direction opposite to an induced magnetic flux that induces counter electromotive force generated in the driving motor only when the current motor voltage is greater than or equal to the threshold voltage; Weak field control method of the steering device drive motor comprising a. The method of claim 1, wherein the step (c) controls the amount of current applied to one or more stators constituting the driving motor so that the reverse magnetic flux component having a sum vector of magnetic flux opposite to the induction magnetic flux is generated. Weak field control method for a steering drive motor. The method of claim 1, wherein in step (c), The magnitude of the reverse magnetic flux is controlled to be proportional to the difference between the current motor voltage or the current motor voltage and the threshold voltage. In the field weakening control device of the automobile steering device drive motor, A sensing unit which periodically reduces the input voltage or the output voltage of the driving motor and transfers the same to the controller; A controller which determines whether an input voltage or an output voltage transmitted from the sensing unit is equal to or greater than a preset threshold voltage, and generates and transmits a reverse magnetic flux generation signal to the performing unit only when the threshold voltage is equal to or greater than a threshold voltage; And An execution unit for receiving a command signal from the controller, and controls the amount of current applied to the coil provided in one or more stators provided in the motor to form the reverse magnetic flux in a direction opposite to the induction magnetic flux that generates the counter electromotive force Weak field controller of the steering drive motor, characterized in that it comprises a.

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