KR20150005808A

KR20150005808A - Apparatus and Method for detecting speed of motor in electro-hydraulic control system

Info

Publication number: KR20150005808A
Application number: KR1020130078876A
Authority: KR
Inventors: 이지상; 설용철; 정완교
Original assignee: 현대모비스 주식회사
Priority date: 2013-07-05
Filing date: 2013-07-05
Publication date: 2015-01-15
Also published as: KR101991138B1

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pressure forming system, and more particularly, to a hydraulic pressure forming system having a torque converter such as an actuator and a screw, and a pressure forming structure such as a cylinder, To an apparatus and method for detecting the persistence, extreme low speed, of a pressure control-based motor which improves the non-ideal acquisition of a permanent speed, a very low speed motor rotation speed,

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electric-hydraulic control system,

FIG. 1 shows a motor control block diagram used in a hydraulic control system using a three-phase AC motor. Referring to FIG. 1, the characteristics of a hydraulic control system, which is controlled in the order of pressure control, speed control, and current control from a pressure command of a desired target structure in order, and a constant load is formed at a constant torque, The forward compensation is constituted.

The voltage command generated in the current controller 100 is pulse-converted by an SVPWM (Space Vector Pulse Width Modulation) algorithm 110, which is applied to the surface-mounted permanent magnet synchronous motor (SPMSM) (130).

The phase currents of the three phases flowing in the three-phase AC motor 130 are fed back to the current controller 100 and the speed at which the motor is rotated is fed back to the speed controller 140 for control. The cylinder pressure obtained from the unidirectional motion of the piston of the cylinder 140 is fed back to the pressure controller 150 through a pressure sensor (not shown) attached to the cylinder 140 and utilized for the control.

As shown in FIG. 1, the rotation speed of the motor rotor is a main control factor for generating a command value of the current controller 100 by being fed back to the speed controller 140. In the industry as a whole, a rotary encoder type sensor is mainly used as a speed sensor of such a three-phase alternating current motor.

The rotary encoder, which is generally attached to the motor rotor, generates A and B pulses of 50% duty with a phase difference of 90 degrees between them as the motor rotates, and outputs them to the microcomputer.

The number of pulses output from the encoder per revolution is a high value as the value is physically determined in the encoder manufacturing process, and the price is high. In order to overcome the limit of the physically determined resolution, the microcomputer increases the number of pulses to be effectively acquired by multiplying the pulses. In the method of acquiring the trigger at the rising and falling of each pulse, it can be doubled or multiplied by 4.

Using four doubled pulses can produce the same effect as using an encoder with four times the number of pulses. From the obtained pulses, there are two methods of converting the rotation speed of the motor into the rotation speed of the control variable: the m-mode advantageous for high speed, the T-scheme advantageous at low speed, Because of the limitations that can only be implemented in a microprocessor, most applications use the m-way. A diagram showing the principle of this m-scheme is shown in Fig.

Assuming that the rotor of the motor rotates at a constant speed, the pulse string as shown in FIG. 2 will be input to the microcomputer from the encoder, and the speed can be detected from the number of pulses (m) obtained for a predetermined time Tc . The m-formulas are summarized as follows.

Here, if Equation (2) is substituted into Equation (1), it can be summarized as follows.

Here, N _f is a speed to be obtained [rpm], Tc is the measurement time [sec], P _PR is the number of pulses per one rotation, m is the displacement measured in radians for the pulse number, X is Tc time during the Tc time to be. In a microcomputer that performs an actual speed detection operation, variables other than the m and Tc values can be input as fixed constant values. Therefore, the measurement time is set to 1 [ms] . &Lt; / RTI >

In the hydraulic control system of various applications such as the braking device of an automobile as shown in the above example, a pressure control application in which a pressure is maintained for a predetermined time is mainly used. At this time, the motor rotates rapidly and pushes the piston. When the cylinder presses to the desired pressure by the displacement of the piston, the pressure is maintained while the motor is almost stopped. From each non-ideal element of the system, (= 0 [rpm]), and it stops at the endless speed and extremely low speed.

FIG. 3 shows a diagram showing an encoder pulse acquisition mode at this time. Referring to FIG. 3, as the pulses are acquired intermittently at constant speeds and at extremely low speeds, and the speed is acquired in the speed acquisition logic and the speed is calculated in the m-mode, When the pulse is received while the detection value is '0', it is obtained in the form of bouncing to the value obtained when one pulse is inputted.

Such a speed detection error is directly reflected in the q-axis current command of the current controller 100, which is the output of the speed controller 140, and causes the motor to be further driven to cause noise and vibration.

Fig. 4 shows a graph showing actual measurement graphs of the d, q-axis current command and the actual values (Idse_ref, Idse, Iqse_ref, Iqse) and the motor rotational speed (rpm) during the constant pressure control of the target system. Referring to FIG. 4, as described above, the fact that the rpm is obtained in a form in which the rpm jumps to a constant value from '0' is directly reflected in the q-axis current command, and as the actual current does not follow it, It can be seen that noise and vibration occur.

1. Korean Patent Publication No. 10-2012-0135832 2. Korean Patent No. 10-1095983

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide an electric hydraulic control system which improves the non-ideal acquisition of the permanent speed and the extremely low speed electric motor rotation speed, And an object thereof is to provide a detection apparatus and method.

Further, the present invention has the same purpose and function as the electric hydraulic control system using the three-phase alternating-current motor, but it improves the speed detection performance of the motor rotor at the time of continuous speed and extremely low speed operation, The present invention has another object to provide a speed detecting apparatus and method of an electric hydraulic control system which has advantages of reducing the cost of the hydraulic control system while not incurring additional H / W costs such as using a high-performance microprocessor or a speed sensor.

In order to achieve the above-described object, the present invention provides a speed detection apparatus for an electric hydraulic control system that improves the non-ideal acquisition of the permanent speed and the extremely low speed electric motor rotation speed occurring in a situation where the target pressure is kept constant.

The speed detection device of the electric hydraulic control system may include:

Electric motor;

An encoder for generating a pulse as the rotor of the electric motor rotates; And

In the non-pulse acquiring interval in which the pulse is not acquired, the counter is incremented every speed acquisition cycle. If the increment of the counter reaches the preset value due to the non-pulse acquiring interval exceeding the preset interval, And a controller for calculating a rotation speed of the electric motor.

At this time, the controller may output the number of pulses calculated as a denominator as the denominator of the number of pulses incremented to the point where the other pulses are input, when another pulse is input in the setting period.

Further, the controller may increment the counter for each speed acquisition period after the input point of the other pulse.

In addition, the controller may decrease the value from the last cycle sample by half every time the speed acquisition cycle passes in the non-pulse acquisition period immediately after passing to the zero speed or extremely low speed range, .

Further, the controller may calculate the rotational speed (rpm) of the motor at a half of the last period sample value.

Further, the controller may calculate the rotation speed (rpm) of the electric motor using an m-mode when a pulse other than the non-pulse acquisition period is input.

Further, the rotation speed of the electric motor may be calculated using the maximum value of the increase amount.

On the other hand, an embodiment of the present invention includes a pulse generating step of generating a pulse as the rotor of the electric motor rotates; A counter increment step of incrementing a counter for each speed acquisition period in a pulse non-acquisition period in which no pulse is obtained; An excess determination step of determining whether the pulse unacquired interval exceeds a preset interval; A preset value arrival determination step of determining whether the increment of the counter has reached a preset value, when the preset interval is exceeded; And a rotational speed calculating step of calculating a rotational speed of the electric motor based on the determination that the electric motor is stopped when the preset value is reached.

According to the present invention, it is possible to improve the performance of the noise and vibration due to improvement of the permanent and extreme low speed detection logic of the electric hydraulic control system using the three-phase AC motor.

Further, another effect of the present invention is that a separate component is not required to improve the detection of the permanent speed and the extremely low speed of the electric hydraulic control system using the three-phase AC motor.

Another advantage of the present invention is that the use of an expensive position sensor is not required for applications requiring high position resolution.

1 is a control block diagram of a three-phase alternating-current motor used for controlling hydraulic pressure in general.
2 is a conceptual diagram showing a principle of detecting a velocity using an m-scheme in general.
FIG. 3 is a diagram showing a state in which the instantaneous pulses are applied to the values at the zero speed and the extremely low speed according to the m-system.
4 is a graph showing rpm, current command and actual current according to an example of a general constant pressure control.
5 is a diagram illustrating an example of the configuration of a hydraulic control system using a three-phase AC motor according to an embodiment of the present invention.
FIG. 6 is a simplified block diagram of a velocity detection apparatus 600 implementing a variable period acquisition scheme in accordance with an embodiment of the present invention.
FIG. 7A is a diagram illustrating an example of applying a variable periodic velocity acquisition method complementary to the initial persistence / ultra-low velocity section velocity according to an embodiment of the present invention. FIG. Speed acquisition method.
8 is a flowchart illustrating a speed detection process using a variable period acquisition method according to an embodiment of the present invention.
FIG. 9 is a graph comparing detection rates of an example in which the variable period acquisition method according to an embodiment of the present invention is applied and an example in which the variable period acquisition method is not used according to an embodiment of the present invention.
10 is a graph showing rpm, current command, and actual current according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and method for detecting a speed of an electric hydraulic control system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

5 is a diagram illustrating an example of the configuration of a hydraulic control system using a three-phase AC motor according to an embodiment of the present invention. 5, an oil pressure control system 600 using a three-phase alternating-current motor includes a three-phase alternating-current motor 530 for generating pressure, as an example of an electric booster, a torque in the direction of rotation of the electric motor 530 in a linear direction A control board (not shown) for controlling the electric motor, other sensors (not shown), electrical elements (not shown), and the like (not shown) Components. These other components include a reservoir 510, a brake pedal 540, a rear wheel M / C 550, a pedal simulator 560, a solenoid valve 570, and the like, do.

FIG. 6 is a diagram illustrating a configuration of a speed detecting apparatus 600 that implements a variable period obtaining method according to an embodiment of the present invention. Referring to FIG. 6, the speed detecting device 600 includes an electric motor 530, an encoder 610 for generating a pulse as the rotor of the motor rotates, a counter 610 for every speed acquisition period, And a controller 620 that determines that the electric motor 530 has stopped and calculates the rotational speed of the electric motor when the incremental amount of the counter reaches a preset value because the pulse non-acquired period exceeds the preset interval .

FIG. 7A is a diagram illustrating an example of applying a variable periodic velocity acquisition method supplemented to the initial persistence / extreme low velocity section velocity measurement according to an embodiment of the present invention.

The basic concept of the algorithm for improving the problems discussed in the background art is to change the speed detection period used for the speed calculation in consideration of the interval in which the pulse (i.e., the encoder pulse) is not obtained.

(1) In a section where pulses are not acquired, the counter is incremented every rate acquisition cycle (= 1 [ms]).

(2) It is judged that the motor is completely stopped when the increment of the counter is 15 when the interval in which the pulse is not obtained exceeds 15 [ms].

Here, 1 [ms] and 15 [ms] are numerical values arbitrarily set for understanding, and other numerical values are also possible.

Referring to FIG. 7A, the variable periodic velocity detection method driven only in the zero velocity state and the extremely low velocity state using this basic concept will be described below.

(3) If a pulse is input in a certain period after a pulse is not acquired, a counter value of a pulse input period is divided by the number of pulses acquired in the corresponding period. The number of pulses (m _c ) considering the period is applied to the existing m-system formula and used for the [rpm] operation. This can be expressed by the following equation.

Here, N _f is the rotational speed of the electric motor to be obtained [rpm], Tc is the measurement time [sec], P _PR is the number of pulses per one rotation, m _c is the cycle number of the considered pulse.

Referring to FIG. 7A, the pulse width is counted by the interval of 1 before the pulse is input, and then 1 / (1 interval count amount) continuously including the point where the a pulse is input in the interval 2 after the a pulse is inputted The number of pulses is output.

At the same time, the pulse is not acquired after the a pulse, and therefore the count is incremented. When the b pulse is acquired, 1 / (② interval count amount) is output from the moment when the b pulse is input. At the same time, since the pulse is not obtained after the b pulse, the counter is incremented.

Since the pulse is not acquired for 15 [ms], it is judged as a speed '0' or it is continued until the next pulse is obtained.

In this way, it is possible to prevent the velocity measurement value from jumping out in a period in which one or a small number of pulses intermittently come in, such as a pressure holding state. In particular, since the time from the moment when the pulse is acquired after the pulse non-acquisition period to the time when the preceding non-acquisition period is divided into the number of inputted pulses, the amount of splash is distributed to the m- Lt; / RTI > Also, the error is minimized in such a manner that the interval at which pulses are input intermittently is also taken into account in the amount of pulses.

In addition, it is necessary to compensate for the fact that the speed is '0' during the first section, which is immediately after the motor has moved to the permanent or extremely low speed region where the electric motor is almost stopped in the rotating region where the electric motor 530 rotates. A diagram showing this is shown in Fig. 7B.

7B is a diagram showing a variable periodic velocity acquisition method in which the initial persistence / extremely low velocity section measurement is complemented. Referring to FIG. 7B, a velocity measurement value rapidly outputting '0' immediately after the entry into the persistent / ultra low speed section is shifted from the last cycle sample by half (720) every time one cycle passes.

The concept shown in Fig. 7B can be added to improve the speed detection m-way for the entire zero speed / very low speed section. A flowchart of the entire variable periodic velocity detection algorithm is shown in Fig.

8 is a flowchart illustrating a speed detection process using a variable period acquisition method according to an embodiment of the present invention. Referring to FIG. 8, it is determined whether the speed of the electric motor 530 is "0" (step S800).

As a result of the determination, if the speed is not zero, it means that the motor is rotating at a high speed, so the rotational speed rmp of the motor is calculated using the existing m-system (steps S801 and S803).

Alternatively, if the speed is zero in step S800, that is, if a pulse is not obtained, nopulse is assigned to the flag, and the count is incremented to check whether the motor is rotating at high speed or is in the fast / slow speed state (steps S810, S820, S830). Further, it is determined whether the sum of the last two cycles of the incremental count is 2 or less. That is, if it is 2 or more, it means that the motor is rotating at a high speed.

If it is determined that the motor is at the zero speed / extremely low speed, the rotation speed (rpm) of the motor becomes the reciprocal of the increment amount of the count until the pulse is acquired (step S850).

Otherwise, if it is determined in step S830 that the sum of the last two periods is greater than or equal to 2, the last pulse value is maintained and the rotational speed is halved (step S835).

When the RPM is calculated, it is confirmed whether a pulse is detected, and it is confirmed whether this pulse is a one-period pulse (steps S835, S860, S870).

FIG. 9 is a graph comparing detection rates of an example in which the variable period acquisition method according to an embodiment of the present invention is applied and an example in which the variable period acquisition method is not used according to an embodiment of the present invention. Referring to FIG. 9, there is shown an original RPM 910 according to a general method and an improved RPM 920 according to an exemplary embodiment of the present invention.

In addition, the rotation speed [rpm] obtained by rotating the motor at zero speed / extremely low speed to compare before and after the algorithm according to an embodiment of the present invention is applied. In the general m-mode, the speed is maintained at '0', and then it is bounced to a certain value. However, when the variable periodic speed detection method is applied, a value close to the actual speed is obtained.

10 is a graph showing rpm, current command, and actual current according to an embodiment of the present invention. Referring to FIG. 10, it can be seen that, under the same conditions as the actual measurement graph, the q-axis current command induced by the speed fluctuation is improved as shown in the graph of FIG. 10 when the pressure is controlled, thereby preventing noise / vibration from occurring.

510: Reservoir
610: Encoder
620:

Claims

Electric motor;
An encoder for generating a pulse as the rotor of the electric motor rotates; And
In the non-pulse acquiring interval in which the pulse is not acquired, the counter is incremented every speed acquisition cycle. If the increment of the counter reaches the preset value due to the non-pulse acquiring interval exceeding the preset interval, A controller for calculating a rotation speed of the electric motor;
And a speed detection unit for detecting the speed of the electric motor.

The method according to claim 1,
Wherein the controller outputs the number of pulses calculated as a denominator as the number of pulses incremented to the point at which the other pulse is input when another pulse is input in the set interval. Device.

3. The method of claim 2,
Wherein the controller increments the counter at every speed acquisition period after the input point of the other pulse.

The method according to claim 1,
The controller may reduce the value from the last period sample by half every time the speed acquisition period passes in the non-pulse acquisition period immediately after passing to the zero speed or extremely low speed range, Wherein the speed detection device of the electric hydraulic control system comprises:

5. The method of claim 4,
Wherein the controller calculates the rotational speed (rpm) of the electric motor at half of the last period sample value.

The method according to claim 1,
Wherein the controller calculates a rotation speed (rpm) of the electric motor using an m-mode when a pulse other than the non-pulse acquisition period is input.

The method according to claim 1,
Wherein the rotation speed of the electric motor is calculated using a maximum value of the increase amount.

A pulse generating step of generating a pulse as the rotor of the electric motor rotates;
A counter increment step of incrementing a counter for each speed acquisition period in a pulse non-acquisition period in which no pulse is obtained;
An excess determination step of determining whether the pulse unacquired interval exceeds a preset interval;
A preset value arrival determination step of determining whether the increment of the counter has reached a preset value, when the preset interval is exceeded; And
A rotational speed calculating step of calculating the rotational speed of the electric motor based on the determination that the electric motor is stopped when the preset value is reached;
Wherein the speed control means is configured to control the speed of the electric motor.

9. The method of claim 8,
And outputting the number of pulses calculated as a denominator as the number of pulses incremented to the point at which the other pulse is input when another pulse is input in the set interval.

10. The method of claim 9,
And incrementing the counter at every speed acquisition period from the input point of the other pulse.

9. The method of claim 8,
When the motor is stopped, the value is halved from the last cycle sample every time the speed acquisition cycle passes in the non-pulse acquisition period immediately after passing to the zero speed or extremely low speed range. A method for detecting the speed of a hydraulic control system.

12. The method of claim 11,
(Rpm) of the motor at a half of the last cycle sample value.

9. The method of claim 8,
And the rotation speed (rpm) of the electric motor is calculated by using the m-mode when another pulse is input in the non-pulse acquisition period.

9. The method of claim 8,
Wherein the rotation speed of the electric motor is calculated using a maximum value of the increase amount.