KR20110121519A - Driving device of centrifugal separator - Google Patents

Abstract

PURPOSE: A centrifugal separator operation apparatus is provided to improve a speed searching function of an inverter when a load with large inertia is stopped and when power is disconnected during high speed operation, thereby smoothly operating a centrifugal separator by synchronizing static frequencies of the inverter and centrifugal separator using a DC braking function while speed reducing. CONSTITUTION: A centrifugal separator(100) comprises a centrifugal separation member(110), a motor(120), an inverter(130), and a microcontroller(140). The motor rotates the centrifugal separation member. The inverter controls rotation speed of a motor according to an external control signal. The microcontroller calculates a delta frequency with a load inertia ratio and deceleration time starting from a frequency before speed searching when power is temporally turned on or off while operating the inverter with a predetermined frequency. The microcontroller reduces the frequency by subtracting the calculated delta frequency from a reference frequency inputted from the outside. A searching control process is performed with the same speed before power turn-on/off by increasing output voltage within a rated current reference range of the motor.

Description

Centrifugal separator driving device {Driving Device of Centrifugal Separator}

The present invention relates to a centrifuge drive device, and more particularly, to a centrifuge drive device for smoothly driving a centrifuge by improving the speed search function of an inverter.

In general, centrifugal separator (centrifugal separator) is a machine that is used for the purpose of dividing the test liquid into several parts by using centrifugal force, is a device for separating the material according to the size and density of the particles when the test solution is put into the test tube and rotated at high speed.

For example, if the separation target is blood, the test solution (blood) is mounted in a centrifuge, and the test solution is rotated by driving at high speed with an inverter. In this case, the inverter receives the operation / stop command and the data of the operating frequency from the microcontroller through the communication method of RS-485.

As shown in FIG. 1, the inverter initially accelerates normally to a set target frequency.

When the power is turned off due to a power failure or the like after reaching the maximum speed, the motor driven by the inverter is decelerated by inertia. When the power failure is restored in that state, the inverter is powered on again, and the speed search function finds the frequency before the power failure and operates without a trip.

However, as shown in FIG. 1, the conventional inverter has an overcurrent trip or an inverter overload function when the power is turned on again to find the previous speed, that is, when there is a slip error between the motor speed and the inverter speed. In this operation, there is a problem that the centrifuge does not operate continuously and stops.

In addition, the inverter stopped at 30 rpm because the inertia of the centrifuge was too large during normal deceleration, but the motor, that is, the centrifuge, continued to operate.

Therefore, it is necessary to improve the performance of the inverter so that the centrifuge can be stopped at a desired time when there is a power failure during high speed operation and when a load with a large inertia stops.

The present invention improves the speed search function of the inverter when there is a power failure during high speed operation and when the load with a large inertia stops, thereby smoothly driving the centrifuge and using the DC brake function during deceleration. And to provide a centrifuge drive device that matched the stop frequency of the centrifuge.

In one embodiment, a centrifuge driving device according to the present invention includes a motor for rotating a centrifuge member, an inverter controlling a rotational speed of the motor according to an external control signal, and a power source temporarily turned off / on during operation of the inverter at a set frequency. When the delta frequency (dF) is calculated from the deceleration time and the load inertia ratio starting from the frequency before the speed search occurs, the calculated delta frequency is subtracted from the reference frequency, which is the target frequency input from the outside, and the frequency is reduced. It may include a microcontroller to increase the output voltage within the current reference range to seek control at the speed before the power is turned off.

According to an aspect of an embodiment of the present invention, the microcontroller includes a dF calculator configured to calculate a delta frequency (dF) based on a deceleration time and a load inertia ratio starting from a frequency before a speed search occurs, and an output of an adder fed back every preset time. An adder which adds and outputs a delta frequency input from the dF calculator to a frequency, a subtractor which reduces the frequency by subtracting the frequency input from the adder to the reference frequency, and compares the speed search frequency with the reference frequency. And an output selector configured to output the frequency inputted from the speed search frequency or the final search frequency.

According to an aspect of the embodiment of the present invention, the output selection unit may output the speed search frequency as the final frequency when the speed search frequency is greater than the reference frequency.

According to an aspect of an embodiment of the present invention, the delta frequency dF may be a difference between a speed at power off and a speed at power on.

According to one embodiment of the present invention, the microcontroller is a subtractor for subtracting an inverter output current detection signal from a rated current reference signal, and multiplying the signal input from the subtractor by a predetermined proportional coefficient k to delta frequency ( a proportional calculator for outputting dF); It may be characterized in that it comprises a voltage output unit for outputting the final voltage for the inverter control by multiplying the speed search frequency.

The present invention improves the speed search function of the inverter when there is a power failure during high speed operation and when the load with a large inertia stops, and also matches the stop frequency of the inverter and the centrifuge by using the DC braking function during deceleration. There is an advantage that can smoothly drive the centrifuge.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings, which do not limit the present invention, and like reference numerals designate like elements in some drawings.
1 is a view showing the inverter driving signal when the power on / off of a typical centrifuge.
2 is a view showing a detailed configuration of a centrifuge applied to the present invention.
3 is a functional block diagram of a microcontroller for output frequency generation according to the present invention.
4 is a functional block diagram of a microcontroller for output voltage generation according to the present invention.
5 is a view showing the inverter driving signal when the power on / off of the centrifuge according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention. The drawings are only examples and are provided for the purpose of easily explaining the principles and concepts of the present invention.

2 is a view showing a detailed configuration of a centrifuge applied to the present invention.

As shown in the figure, the centrifuge 100 includes a centrifuge member 110, a motor 120, an inverter 130, a microcontroller 140, an operation unit 160, a DC converter 170, and the like.

The centrifuge member 110 is centrifuged to separate the test liquid contained in the test tube by the rotation, the motor 120 is rotated in accordance with the supplied power to rotate the centrifuge member 110, the inverter 130 Is to control the rotational speed of the motor 120 in accordance with an external control signal.

The microcontroller 140 outputs an operation and stop command to the inverter 130 and an operation frequency set for a predetermined time to the motor 120 according to a command input from the outside and the current and frequency fed back through the output terminal of the inverter 130. To control the rotation speed.

In addition, when the power controller is temporarily turned off / on due to a power failure during operation of the inverter 130 at the set frequency, the microcontroller 140 is turned off before the speed search is generated. The delta frequency (dF: delta frequency) is calculated from the deceleration time and the load inertia ratio, starting with the frequency before it is turned off, and then the calculated delta frequency is subtracted from the target frequency, RefFreq, which is input from the outside. To reduce and increase the output voltage within the rated current reference range of the motor 120 to control the search at the speed before the power is turned off.

In addition, the operation unit 160 receives the operation, stop and rotation speed of the centrifuge 100 from the user, the DC converter 170 receives a commercial AC power supplied from the outside (for example, AC 220V) a predetermined DC voltage And the converted DC voltage is supplied to the overall circuit part of the centrifuge.

When the motor 120 of the centrifuge 100 reaches the maximum speed according to the control of the inverter 130 and then the power is turned off due to a situation such as a power failure, it is driven by the inverter 130 The motor 120 is decelerated by inertia.

When the power failure is restored (power on) in that state, power is supplied to the inverter 130 again, and the microcontroller 140 controls the inverter 130 without a trip by finding a frequency before the power failure with a speed search function.

Here, the microcontroller 140 improves the speed search function of the inverter 130 to smoothly drive the centrifuge 100, so that the stop frequency of the inverter 130 and the centrifugal separator ( It is necessary to match the stop frequency of 110). In addition, the microcontroller 140 performs only P control in order to simplify control and facilitate gain tuning.

3 is a functional block diagram of a microcontroller for generating an output frequency according to the present invention, and includes a dF calculator 141, an adder 143, a subtractor 145, and an output selector 147.

The dF calculator 141 calculates and outputs the delta frequency dF based on the deceleration time and the load inertia ratio starting from the frequency before the speed search occurs. The delta frequency dF is a speed difference between power off and power on.

The adder 143 feedbacks the delta frequency input from the dF calculator 141 and the frequency output from the adder 143 every predetermined time (for example, 1 ms interrupt), adds the feedback, and outputs an updated frequency. 145 decreases the frequency by subtracting the frequency input from the adder 143 to a reference frequency which is a target frequency input from the outside.

The output selector 147 compares the speed search frequency and the reference frequency with each other and outputs the frequency or speed search frequency input from the subtractor 145 as the final frequency Fout. That is, the output selector 147 outputs the speed search frequency as the final frequency when the speed search frequency is greater than the reference frequency, and outputs the frequency output by the subtractor as the final frequency when the speed search frequency is smaller than the reference frequency. Done. In this case, the speed search frequency is a frequency calculated by proportionally controlling the difference between the rated current reference signal FlyingStartPerc and the inverter output current detection signal CurrMag, which will be described in detail with reference to FIG. 4.

That is, FIG. 3 generates an actual output frequency while cumulatively increasing the speed difference at power-off and the speed difference at power-on, that is, the delta frequency (dF).

When the power is off, the speed of the motor 120 is high, and when the power is off, the frequency gradually decreases. Then, when the power is turned on again, the frequency is lower than when turned off, so the difference is continuously added to find the frequency at the time of power-off. Therefore, it is called speed search.

The delta frequency is changed according to the deceleration time and inertia ratio. If the deceleration time and inertia ratio is large, the delta frequency is small, and if the deceleration time and inertia ratio is small, the delta frequency is large.

Here, when the regenerative mode is not used, that is, when the speed search frequency is smaller than the reference frequency, the adder 143 receives and adds the delta frequency input from the dF calculator 141 and the frequency output from the adder 143 to feed back. Then, the updated frequency is output to the subtractor 145, and the subtractor 145 subtracts the frequency input from the adder 143 from the reference frequency, which is a target frequency, to the final frequency Fout through the output selector 147. Output

On the other hand, in the regenerative mode, that is, when the speed search frequency is greater than the reference frequency, the speed search frequency is output as the final frequency Fout through the output selector 147.

The output frequency starts with the frequency before the speed search occurs and obtains the delta frequency based on the deceleration time and load inertia ratio, adds the frequency every 1ms interrupt, and then decelerates the frequency by subtracting from the reference frequency.

The present invention obtains the delta frequency by setting the deceleration time and the inertia ratio as an adjustment parameter so that the speed before power failure can be found at a faster time. This lengthens.

In particular, in order to search for speed at a high speed (for example, 8000 rpm), a fast estimation of the speed search is required. An overcurrent fault occurs.

4 is a functional block diagram of a microcontroller for generating an output voltage according to the present invention, and includes a subtractor 151, a proportional operator 153, an adder 155, and a voltage output unit 157.

The subtractor 151 subtracts and outputs the inverter output current detection signal CurMMag to the rated current reference signal FlyingStartPerc. The rated current reference signal (FlyingStartPerc) is a ratio with respect to the rated current of the motor 120, which indicates the maximum current level during the speed search, and corresponds to, for example, 180% of the rated current of the motor 120. It can indicate the current level. The inverter output current detection signal CurrMag is a signal detected from a current transformer installed at an output terminal of the inverter 130 and represents a magnitude of a current obtained by reading a three-phase current from the current transformer and performing DQ conversion.

The proportional operator 153 multiplies a signal input from the subtractor 151 by a predetermined proportional coefficient k to output a delta frequency dF, and the adder 155 receives a delta frequency input from the proportional operator 153. (dF) and the speed search frequency are fed back and added to output the updated speed search frequency.

The voltage output unit 157 outputs a final voltage Vout proportional to the speed search frequency input from the adder 155.

On the other hand, when the rated current reference signal FlyingStartPerc is smaller than the inverter output current detection signal CurrMag, the voltage output unit 157 outputs from the adder 155 to the value obtained by dividing the fundamental frequency by the set rated voltage V. The speed search frequency is multiplied to output the final voltage Vout for inverter control.

That is, since a frequency for controlling the inverter is obtained in FIG. 3, a voltage proportional to the frequency is obtained and output in FIG. 4.

The output voltage rises from '0' to the voltage before speed search occurs. The current flows up to reach the shortest time while the current flowing is within the current level of the set rated current reference signal (FlyingStartPerc).

Referring to FIGS. 3 and 4, the overall operation of the microcontroller 140 will be described below.

The actual output frequency is generated while accumulating and increasing the speed difference at power-off and the speed difference at power-on, that is, the delta frequency (dF). Here, when the power is off, the speed of the motor 120 is high, and when the power is off, the frequency is gradually decreased.

When the power is back on, the frequency is lower than when it is off, so take the difference and continue to find the frequency at power off. Then, the difference between the rated current reference signal FlyingStartPerc and the inverter output current detection signal CurrMag is proportionally controlled, and an output voltage proportional to the output frequency obtained in FIG. 3 is obtained and output.

The output voltage rises from 0 to the voltage before the speed search occurs, and the current flows up to reach the shortest time while being within the current level of the set rated current reference signal FlyingStartPerc.

In general, since the rated voltage (V) and the fundamental frequency (Fbase) is different for each motor, it is difficult to control the actual output voltage accordingly, so that an overcurrent flows to the motor and thus acceleration does not occur. Reflect when making output voltage by setting.

As shown in Fig. 5, if the output current increases excessively during speed search, the output voltage is set to '0' to suppress the voltage rise and at the same time suppress the output current.

In general, speed search ends after speed search ends up to the target frequency. In this case, continuous operation such as overcurrent trip or overvoltage trip is impossible when control mode is switched to normal acceleration after reaching high frequency by PI control. It was.

However, in the present invention, when the current speed is estimated, that is, the speed search is immediately terminated at a low frequency, the normal acceleration slope is increased to the target frequency to operate without failure, and the speed search time is also increased.

The present invention has been described with reference to the preferred embodiments, and those skilled in the art to which the present invention pertains to the detailed description of the present invention and other forms of embodiments within the essential technical scope of the present invention. Could be. Here, the essential technical scope of the present invention is shown in the claims, and all differences within the equivalent range will be construed as being included in the present invention.

100: centrifuge 110: centrifuge member
120: motor 130: inverter
140: microcontroller 141: dF calculation unit
143: adder 145: subtractor
147: output selector 151: subtractor
153: proportional calculator 155: adder
157: voltage output unit 160: operation unit
170: DC converter

Claims (5)

A motor for rotating the centrifuge member;
An inverter controlling the rotational speed of the motor according to an external control signal; And
When the inverter is temporarily turned off / on while operating the inverter at the set frequency, the delta frequency (dF) is calculated from the deceleration time and the load inertia ratio starting from the frequency before the speed search occurs, and then the calculated delta frequency is input from the outside. And a microcontroller which reduces the frequency by subtracting from the reference frequency, which is a frequency, and increases the output voltage within the rated current reference range of the motor to search and control at a speed before the power is turned off.
The method of claim 1,
The microcontroller,
A dF calculator configured to calculate a delta frequency (dF) based on a deceleration time and a load inertia ratio starting from a frequency before a speed search occurs;
An adder for adding the delta frequency input from the dF calculator to the output frequency of the adder fed back at a preset time;
A subtractor for reducing the frequency by subtracting the frequency input from the adder to the reference frequency; And
And an output selector for comparing the speed search frequency and the reference frequency with each other and outputting the frequency inputted from the subtractor or the speed search frequency as a final frequency.
The method of claim 2,
And the output selector outputs the speed search frequency as the final frequency when the speed search frequency is greater than the reference frequency.
The method of claim 2,
The delta frequency (dF) is a centrifuge drive device, characterized in that the speed difference between the power-off speed and the power-on.
The method of claim 1,
The microcontroller,
A subtractor for subtracting the inverter output current detection signal from the rated current reference signal;
A proportional calculator for outputting a delta frequency dF by multiplying a signal input from the subtractor by a predetermined proportional coefficient k;
An adder configured to output the updated speed search frequency by adding feedback from the delta frequency and the speed search frequency inputted from the proportional operator; And
And a voltage output unit configured to output a final voltage for inverter control by multiplying a speed search frequency input from the adder by a value obtained by dividing a basic frequency by a preset rated voltage.

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