KR20160069416A - Electric current control apparatus of motor and method thereof - Google Patents

Abstract

The purpose of the present invention is to provide an apparatus and a method to control a current of a motor capable of improving robustness for a noise and reactivity by using one low pass filter when a feedback current outputted by the motor is a static state or a dynamic state. The present invention relates to the apparatus and the method to control a current of a motor. The apparatus comprises: a motor control unit to supply power to the motor depending on a motor operating signal; a current detecting unit to detect a motor current outputted from the motor; a low pass filter to filter the motor current to a preset band; and a microcomputer to calculate an actually measured current value based on the filtered motor current, to divide the current value into a dynamic region and a static region in accordance with a difference value between a preset target current value and the actually measured current value, to set interrupt time for the sampling of an analog-digital converter (ADC) in accordance with the divided region, and to control the sampling number of the ADC in accordance with the set interrupt time.

Description

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

The present invention relates to an apparatus and method for controlling a current of a motor, and more particularly, to an apparatus and method for controlling a current of a motor by dividing a dynamic region into a static region based on a feedback current output from the motor, The present invention relates to an apparatus and method for controlling a current of a motor that sets an interrupt time for sampling an analog-to-digital converter (ADC) and adjusts the sampling frequency of the ADC according to an interrupt time.

The suspension system of the vehicle connects the axle and the vehicle body and prevents vibration or impact from the road surface to be transmitted directly to the vehicle body when the vehicle is running, thereby preventing damage to the vehicle body or the cargo and improving the ride quality. The braking force of each wheel at the time of braking or driving force is transmitted to the vehicle body, and at the same time, the braking force of each wheel is resistant to the centrifugal force at the time of turning and supports each wheel at a proper position with respect to the vehicle body. Minimize the vibration of the body by absorbing impact.

These suspension devices detect the state of the vehicle and the road surface from various sensors, control the garage by controlling the spring constant, the damping force of the damper, and the circuit pressure of the air or the pneumatic pressure spring, In order to control the damping force of the damper, precise control of the current applied to the motor is very important. Although the motor for controlling the suspension of the vehicle has been described as an example, the present invention can also be applied to motors for controlling devices provided in an automobile. In addition, the current control technology of the motor can be applied not only to an automobile but also to various fields requiring current control of the motor.

Conventionally, there is a hardware feedback method that performs PWM (Pulse Width Modulation) control by differentially integrating a difference between a target current and a detected current, or a hardware feedback method in which a detected current is subjected to low frequency filtering and a PI controller The motor current is controlled by a software feedback method that calculates the PWM duty and controls the motor current.

In order to control the motor current, if the state of the feedback current is static as shown in FIG. 1, a strong filter should be used to improve the robustness against noise. If the feedback current state is variable, a weak filter do.

However, there is a problem that it is difficult to satisfy the static state and the variable state because one filter is fixed by hardware.

In addition, when two strong filters and weak filters are used, two separate analog-to-digital converters (ADCs) are assigned to the outside, and a separate RC filter is designed There is a disadvantage that the system price is expensive.

Korean Patent Publication No. 2008-0086421, entitled " Analog-to-Digital Conversion &

An object of the present invention is to provide a motor current control device and method for improving the robustness against noise and reactivity using a single low-pass filter even when the feedback current output from the motor is in a static or variable state .

According to an aspect of the present invention, there is provided a motor control apparatus including a motor control unit for supplying power to a motor in accordance with a motor drive signal, a current sensing unit for sensing a motor current output from the motor, A low pass filter for filtering the motor current, a measured current value applied to the motor based on the filtered motor current, and a dynamic range according to a difference between the predetermined target current value and the measured current value, And a static area, and sets an interrupt time for sampling an ADC (Analog-Digital Converter) according to the divided area, and controls a sampling frequency of the ADC according to the set interrupt time. A current control device for a motor is provided.

Wherein the microcomputer comprises an analog-to-digital converter (ADC) for converting the filtered motor current of the analog form into a digital form while adjusting the number of sampling times according to an interrupt time set by the drive signal generator, A difference value calculation unit for calculating a measured current value applied to the motor and comparing the target current value and the measured current value to obtain a difference value; And a driving signal generator for setting an interrupt time for sampling the ADC according to the divided area.

The driving signal generating unit may divide the driving signal generating unit into a variable area when the difference value is larger than the reference value and the static area if the difference value is not greater than the reference value.

The driving signal generator sets the interrupt time so as to perform fast sampling based on the period of the waveform in the case of the variable area, uses the set interrupt time as a trigger signal for sampling the ADC, The interrupt time is set to be long so that slow sampling is performed based on the waveform period and the set interrupt time can be used as a trigger signal for sampling the ADC.

The driving signal generating unit may adjust the motor driving signal based on the difference value calculated by the difference calculating unit, and may transmit the adjusted motor driving signal to the motor control unit.

According to another aspect of the present invention, there is provided a method of controlling a current in a motor, the method comprising the steps of: (a) detecting a motor current output from the motor; (b) (C) calculating a measured current value applied to the motor based on the filtered motor current; and (d) calculating a measured current value applied to the variable region and the static current value according to a difference between the preset target current value and the measured current value. And (e) setting an interrupt time for sampling the ADC differently according to the divided area.

Wherein the step (c) includes the steps of: converting the filtered analog current into a digital form while adjusting the number of sampling times according to the set interrupt time, calculating a measured current from the motor current converted to the digital form, And a step of calculating a value.

The step (d) includes the steps of: obtaining a difference value between the target current value and a measured current value; comparing the difference value with a predetermined reference value; dividing the difference value into a variable area when the difference value is greater than a reference value; And if it is not greater than the reference value, dividing into a static area.

In the step (e), the interrupt time is set to be short so that fast sampling is performed based on the period of the waveform in the case of the variable area, and the set interrupt time is used as a trigger signal for sampling the ADC. The interrupt time is set to be long so that slow sampling is performed based on the cycle of the ADC, and the set interrupt time can be used as a trigger signal for sampling the ADC.

According to the present invention, a dynamic area and a static area are classified into a dynamic area and a static area based on a feedback current output from a motor. An interrupt time for sampling the ADC is set differently according to the divided area, By adjusting the sampling frequency of the ADC according to the interrupt time, even if the feedback current output from the motor is in a static or variable state, one low-pass filter can be used to improve the robustness against noise as well as the reactivity.

1 is a view for explaining a conventional motor current control method;
2 is a block diagram schematically showing a configuration of a current control device for a motor according to an embodiment of the present invention.
3 is a block diagram showing a configuration of a microcomputer shown in Fig.
4 is a diagram illustrating a method of controlling a current of a motor by a current control device according to an embodiment of the present invention.
5 is a diagram illustrating sampling according to an interrupt time in a variable area according to an embodiment of the present invention;
FIG. 6 is an exemplary diagram illustrating sampling according to an interrupt time in a static area according to an embodiment of the present invention; FIG.

The foregoing and other objects, features, and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and method for controlling a current of a motor according to the present invention will be described in detail with reference to the accompanying drawings. The embodiments are provided so that those skilled in the art can easily understand the technical spirit of the present invention, and thus the present invention is not limited thereto. In addition, the matters described in the attached drawings may be different from those actually implemented by the schematic drawings to easily describe the embodiments of the present invention.

In the meantime, each constituent unit described below is only an example for implementing the present invention. Thus, in other implementations of the present invention, other components may be used without departing from the spirit and scope of the present invention. In addition, each component may be implemented solely by hardware or software configuration, but may be implemented by a combination of various hardware and software configurations performing the same function. Also, two or more components may be implemented together by one hardware or software.

Also, the expression " comprising " is intended to merely denote that such elements are present as an expression of " open ", and should not be understood to exclude additional elements.

Hereinafter, the present invention is limited to the current control of the motor. However, the present invention can be applied to various fields requiring current control such as a hydraulic solenoid.

In addition, it can be applied to various fields in which the sampling frequency of an ADC (Analog-Digital Converter) needs to be adjusted.

FIG. 2 is a block diagram schematically showing a configuration of a current control device for a motor according to an embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of a microcomputer shown in FIG.

2, the motor current control apparatus 200 includes a motor 210, a motor control unit 220, a current sensing unit 230, a low pass filter 240, and a microcomputer 250 do.

The motor control unit 220 supplies power to the motor 210 according to a motor driving signal input from the microcomputer 250. The motor control unit 220 switches and stops the motor 210 under the control of the microcomputer 250. That is, the motor control unit 220 is switched on in response to the motor drive signal output from the microcomputer 250 to supply electric power to the motor 210 to drive the motor 210, and is similarly switched off according to the motor drive signal Power is not supplied to the motor 210, and the motor 210 is stopped. Here, the motor driving signal may be, for example, a pulse width modulation (PWM) signal, and the motor control unit 220 supplies power enough to drive the motor 210 in response to the PWM pulse.

The current sensing unit 230 senses the motor current output from the motor 210. That is, the current sensing unit 230 detects the motor current output from the motor 210 when the motor is driven.

The low-pass filter 240 filters the motor current sensed by the current sensing unit 230 to a predetermined band. The low-pass filter 240 is formed by connecting a resistor R and a capacitor C in parallel. The low-pass filter 240 filters the motor current sensed by the current sensing unit 230 to a preset predetermined band, And outputs the extracted signal to the ADC input port of the microcomputer 250.

Since the low-pass filter 240 filters a frequency higher than a predetermined frequency, the low-pass filter 240 is provided to remove noise due to a frequency higher than a predetermined frequency. At this time, the used low-pass filter 240 may be, for example, a weak filter.

The microcomputer 250 calculates a measured current value applied to the motor 210 based on the motor current filtered by the low-pass filter 240, and calculates a dynamic value according to a difference between a predetermined target current value and a measured current value. separated by a region and a static (static) zone, and, according to the segment regions ADC - and different interrupt (interrupt) time for sampling (sampling) set of (analog-digital converter, analog to digital converter), according to the set interrupt time Adjust the sampling frequency of the ADC.

The microcomputer 250 receives the filtered current through the low-pass filter 240 and converts the analog signal into a digital signal while adjusting the sampling frequency according to the interrupt time set according to the variable area or the static area, So that the current can be calculated. Then, when the actual current calculated by the microcomputer 250 is lower than the current required for the motor 210, the motor driving signal (for example, the pulse width modulation signal) And when the current is higher than the current required for the motor 210, the motor driving signal is adjusted to control the signal delivery control so that the current applied to the motor 210 can be lowered. That is, the microcomputer 250 adjusts the PWM signal to limit the current when the measured current is higher than the amount of current required by the motor 210, and when the measured current is lower than the amount of current required by the motor 210, The duty is varied to adjust the supply of sufficient current.

The microcomputer 250 is a central processing unit of the motor current control apparatus 200. The microcomputer 250 controls the motor 210 to drive or stop the motor 210 by outputting a motor drive signal and controls the motor 210 according to the difference between the target current value and the measured current value And sets the interrupt time for sampling the ADC to be different according to the divided area. By controlling the motor driving signal by controlling the motor driving signal based on the difference value, the target current value and the actual current Minimize the error between values.

Referring to FIG. 3, the microcomputer 250 includes an ADC 252, a difference value calculator 254, and a driving signal generator 256.

The ADC 252 converts the analogized motor current filtered in the low pass filter 240 into a digital form. The ADC 252 converts an analog type motor current into a digital form so that the microcomputer 250 can interpret the current so that the microcomputer 250 can calculate a measured current value when the motor is driven.

At this time, the ADC 252 adjusts the number of sampling times according to the interrupt time set by the driving signal generating unit 256, and converts the analogized filtered motor current into a digital form. That is, the ADC 252 performs fast sampling on the basis of the waveform period according to the interrupt time in the case of the variable area, and performs slow sampling on the waveform period according to the interrupt time in the case of the static area. .

The difference value calculation unit 254 calculates a measured current value applied to the motor 210 from the motor current converted into the digital form by the ADC 252 and compares the measured current value with a predetermined target current value to obtain a difference value . At this time, the difference value calculator 254 can obtain the measured current value corresponding to the digitally converted motor current from the pre-stored database (not shown). Here, it is preferable that the database stores the result of the predetermined formula made by the resolution and input conditions of the ADC 252.

The drive signal generator 256 compares the difference value obtained by the difference value calculator 254 with a preset reference value and divides the difference value into a variable area and a static area and sets an interrupt time for sampling the ADC 252 according to the divided area And uses the set interrupt time as the trigger signal of the ADC 252. [ That is, the driving signal generator 256 compares the difference value with the reference value, and divides the difference into a variable area when the difference value is larger than the reference value and the static area when the difference value is not larger than the reference value. Then, in the case of the variable area, the driving signal generator 256 sets the interrupt time to be short so that fast sampling is performed based on the waveform period, and uses the set interrupt time as a trigger signal for sampling the ADC 252 . At this time, the drive signal generator 256 may set the interrupt time to a shorter time by various methods such as a preset time unit or a cycle unit based on the waveform period. If the interrupt time for sampling the ADC 252 is shortened, the number of sampling times per cycle of the ADC 252 increases and the number of average applied data (data) can be reduced to improve the reactivity. That is, in the case of the variable area, the interrupt time is set to be short so that fast sampling is performed based on the period of the waveform. For example, an interrupt time is set such that an even number of sampling numbers are set to integer multiples of the waveform period.

For example, PWM of 1 ms cycle will be described.

If an interrupt occurs in 250us units, 4 times sampling is performed. In this case, the load of the microcomputer is small, but since the signal accuracy is degraded, the average number of applied data is set to 4 or more. If an interrupt occurs in 125us units, 8 samplings are performed. In this case, since the load of the microcomputer is medium and the signal accuracy is medium, in order to improve the reactivity, the average number of applied data is set to 4 or less, and in order to improve the stability, the average applied data number is set to 4 or more. If an interrupt occurs in 62.5us units, 16 samplings are performed. In this case, since the load of the microcomputer is large and the signal accuracy is high, the average number of applied data is set to 4 or less in order to improve the reactivity and the average applied data number is set to 4 or more in order to improve the stability.

In the case of the static area, the driving signal generator 256 sets the interrupt time to be long so that slow sampling is performed based on the waveform period, and uses the set interrupt time as a trigger signal for sampling the ADC 252 . At this time, the drive signal generator 256 can set the interrupt time to be long by various methods such as a preset time unit, a cycle unit, etc. based on the waveform period. If the interrupt time for sampling the ADC 252 is increased, the number of sampling times per cycle of the ADC 252 is reduced, and the number of average applied data is increased to ensure stability. That is, in the case of the static area, the interrupt time is set to be long so that slow sampling is performed based on the period of the waveform.

The drive signal generator 256 adjusts the motor drive signal based on the difference calculated by the difference calculator 254 and transmits the adjusted motor drive signal to the motor controller 220

The drive signal generator 256 outputs a PWM signal by a motor drive signal. The drive signal generator 256 estimates a current supplied to the motor 210 by receiving a feedback signal and uses the current to estimate the current supplied to the motor 210 And controls the current to be applied to the motor 210 to be increased when the current is lower than the required current.

The current controller 200 of the motor configured as described above can satisfy both the case where the feedback current state is a static state and the case where a feedback state is variable by using one low-pass filter 240.

FIG. 4 is a diagram illustrating a method of controlling a current of a motor according to an embodiment of the present invention. FIG. 5 is a diagram illustrating sampling according to an interrupt time in a variable area according to an embodiment of the present invention. FIG. 6 is an exemplary diagram for explaining sampling according to an interrupt time in a static area according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 4, the current control apparatus detects the motor current output from the motor (S402), and filters the detected motor current to a predetermined band (S404).

The current control device converts the filtered analog current into a digital form (S406), and calculates a measured current value applied to the motor from the motor current converted into the digital form (S408). At this time, the current control device converts the filtered analog type motor current into digital form while adjusting the sampling frequency according to the interrupt time set according to the variable area or the static area.

Thereafter, the current controller obtains a difference value between the predetermined target current value and the measured current value (S410). The difference value is compared with a predetermined reference value to determine whether the difference value is larger than the reference value (S412).

If it is determined in step S412 that the difference value is larger than the reference value, the current controller divides the variable area into a variable area (S414), sets the interrupt time for sampling the ADC to be short (S416) And provides it to S406 for use as a signal (S418). At this time, the current controller sets the interrupt time to be short so as to perform fast sampling based on the waveform period. If the interrupt time is shortened in the variable area, the number of sampling times per cycle is increased as shown in FIG. In this case, it can be seen that as the number of sampling increases, reactivity can be ensured according to the signal change.

If it is determined in step S412 that the difference value is not greater than the reference value, the current control apparatus classifies the static area into a static area (S420), sets an interrupt time for sampling the ADC to be long (S422) (S418) for use as a trigger signal for S406. At this time, the current controller sets the interrupt time to be long so that slow sampling is performed based on the waveform period. If the interrupt time is made longer in the static area, the number of sampling times per cycle is reduced as shown in FIG. In this case, as the number of sampling times is reduced, the load of the microcomputer is reduced and stable signal processing is possible.

The current control method of such a motor can be created by a program, and the codes and code segments constituting the program can be easily deduced by a programmer in the field. Further, the program relating to the current control method of the motor can be stored in an information storage medium (Readable Media) readable by the electronic device, readable and executed by the electronic device.

Thus, those skilled in the art will appreciate that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

200: current control device 210: motor
220: motor control unit 230: current sensing unit
240: low-pass filter 250:

Claims (9)

A motor control unit for supplying power to the motor in accordance with the motor drive signal;
A current sensing unit sensing a motor current output from the motor;
A low pass filter for filtering the motor current to a predetermined frequency band; And
Calculating a measured current value applied to the motor based on the filtered motor current and dividing the measured current value into a dynamic range and a static range according to a difference between a preset target current value and a measured current value, A microcomputer configured to set an interrupt time for sampling an analog-digital converter (ADC) according to the divided area and to adjust a sampling frequency of the ADC according to the set interrupt time;
And a current control unit for controlling the current of the motor.
The method according to claim 1,
The microcomputer,
An analog-to-digital converter (ADC) for converting the filtered motor current of the analog form into a digital form while adjusting the sampling frequency according to the interrupt time set by the drive signal generating unit;
A difference value calculation unit for calculating a measured current value applied to the motor from the motor current converted into the digital form and comparing the target current value and the measured current value to obtain a difference value; And
And a drive signal generator for comparing the difference value with a preset reference value to divide the variable area into a static area and an interrupt time for sampling the ADC according to the divided area, Device.
3. The method of claim 2,
Wherein the driving signal generator divides the difference into a variable area when the difference value is larger than the reference value and divides the difference into a static area when the difference value is not larger than the reference value.
3. The method of claim 2,
The driving signal generating unit sets the interrupt time to be shorter in order to perform fast sampling based on the period of the waveform in the case of the variable area, uses the set interrupt time as a trigger signal for sampling the ADC, The interrupt time is set to be long so that slow sampling is performed based on the cycle of the ADC, and the set interrupt time is used as a trigger signal for sampling the ADC.
3. The method of claim 2,
Wherein the drive signal generation unit adjusts the motor drive signal based on the difference value calculated by the difference value operation unit and transmits the adjusted motor drive signal to the motor control unit.
A method of controlling a current in a motor by a current control device,
(a) detecting a motor current output from the motor;
(b) filtering the detected motor current to a predetermined band;
(c) calculating a measured current value applied to the motor based on the filtered motor current;
(d) dividing into a variable region and a static region according to a difference between a preset target current value and a measured current value; And
(e) setting an interrupt time for sampling the ADC differently according to the divided area;
And a current control method of the motor.
The method according to claim 6,
The step (c)
Converting the filtered analog motor current into a digital form while adjusting a sampling frequency according to the set interrupt time; And
And calculating a measured current value applied to the motor from the motor current converted into the digital form.
The method according to claim 6,
The step (d)
Obtaining a difference value between the target current value and the measured current value;
Comparing the difference value with a preset reference value; And
If the difference value is larger than the reference value, dividing the difference region into a variable region, and if the difference value is not larger than the reference value, dividing the difference region into a static region.
The method according to claim 6,
The step (e)
In the case of the variable area, the interrupt time is set to be short so that fast sampling is performed based on the waveform period, and the set interrupt time is used as a trigger signal for sampling the ADC. In the case of the static area, The interrupt time is set to be long so that sampling is performed, and the set interrupt time is used as a trigger signal for sampling the ADC.

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