JP2000055522A - Controller and control method for compressor in refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect an inverter and a compressor by detecting each phase voltage of three-phase power supply lines between the inverter and the compressor and stopping driving of the compressor when a decision is made based on the detection results that a defective connection has occurred where at least one phase is opened. SOLUTION: A control section 50 applies a switching signal to an inverter 20 through an inverter drive section 60 and drives a compressor 30 for a predetermined time. A position sensing section 40 senses the counter electromotive force in each phase of the compressor 30 and determines the rotor position and the r.p.m. A phase voltage sensing section 90 senses the counter electromotive force in each phase and delivers a phase voltage detection signal. When at least one phase is opened, the phase voltage does not appear in that phase and the transistor at the phase voltage sensing section 90 is sustained in off state. When a low signal delivered continuously from the phase voltage sensing section 90, the control section 50 makes a decision that the connection between the inverter 20 and the compressor 30 is opened and stops the compressor 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor control apparatus and method for a refrigerator, and more particularly, to any one of three-phase power supply lines supplied to a compressor from an inverter that drives a compressor using a brushless DC motor. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor control apparatus and method for a refrigerator for stopping the operation of a compressor when at least one phase is opened or a change in the rotation speed of the compressor exceeds a threshold value within a predetermined time.

[0002]

2. Description of the Related Art A conventional inverter refrigerator will be described below with reference to FIG. FIG. 1 is a block diagram of a conventional compressor control device for a refrigerator. As shown in FIG. 1, the conventional refrigerator includes a power supply unit 3 that supplies power, an inverter 11 that converts a power supply output from the power supply unit 3 into a three-phase power supply,
And a compressor 13 driven by a three-phase power supply output from the inverter 11. A brushless DC motor is used as the compressor 13.

Further, a position sensor 4 for sensing a rotor position through a back electromotive force generated from the compressor 13 to determine an operation speed of the compressor 13 and an output signal of the position sensor 4 are applied. A control unit 7 for outputting a control signal corresponding thereto, and an inverter drive unit 9 for outputting a drive signal to the inverter 11 so that the compressor 13 is driven according to the control signal output from the control unit 7. Further included.
The inverter 11 receives a driving signal output from the inverter driving unit 9 and alternately turns on / off six internal power transistors (not shown) to change the power output from the power supply unit 3 into three phases. (U-phase, v-phase, w-phase) power.

The operation of such a conventional refrigerator will be described as follows. When the compressor 13 is turned on, the control unit 7 outputs a control signal to the inverter driving unit 9 to drive the compressor 13, and the six power transistors inside the inverter 11 are alternately turned on / off. Compressor 1
3 is supplied with three-phase power. In controlling the compressor 13 using such a brushless DC motor,
When the compressor 13 is initially driven, the controller 13 cannot grasp the position of the rotor. Therefore, the controller 7 causes the inverter 11 to apply an arbitrary switching signal irrespective of the rotor position during the initial fixed period to gradually start the compressor 13. To accelerate.

Thereafter, when the rotation speed of the compressor 13 reaches the normal rotation speed band, the control unit 7 controls the compressor 13 normally using the position detection signal output from the position sensing unit 4. In this manner, a section in which an arbitrary switching signal is applied to each phase regardless of the rotor position at the time of the initial drive of the compressor 13 is referred to as a step drive section.

However, if any one of the three-phase power supply terminals is open from the three-phase power supply connection terminal connected from the inverter 11 to the compressor 13, the two phases will be switched after the step drive for a certain time. 13 is applied to the position sensing unit 4 while the remaining one phase is
Therefore, the waveform initially applied by the control unit 7 is continuously applied to the position sensing unit 4.

As a result, an abnormal switching signal is generated, and the compressor 13 operates abnormally or vibrates due to the abnormal switching signal.
In other words, since the position detection of one phase is not performed normally, abnormal switching occurs in the transistor inside the inverter 11 and a large amount of heat is generated in the transistor, thereby causing a problem that the inverter 11 is damaged. .

When it is determined whether or not the compressor 13 normally operates using only the position sensing unit 4 as described above, the position sensing unit 4 determines whether or not the compressor 11 is located between the inverter 11 and the compressor 13. Compressor 13 through the line potential difference of the phase connection line
Since the rotor position and the number of rotations are determined, if one of the phases is actually open and a connection failure occurs,
The control unit 7 does not know which defective line is,
It was only known whether the compressor 13 normally operates using the rotation speed of the compressor 13 only. Further, when an abnormal situation occurs in which the difference between the low rotation speed and the high rotation speed becomes equal to or more than a certain range during the operation after the compressor 13 is normally started, the compressor 13 is continuously driven and the compressor 13 There is also a problem that the life is shortened.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its object is to supply a compressor from an inverter that drives a compressor using a brushless DC motor. The inverter and the compressor can be protected by stopping the operation of the compressor when any one of the phases of the three-phase power line is opened or when the rotation speed of the compressor exceeds a critical value within a predetermined time. An object of the present invention is to provide a refrigerator compressor control device and method.

Another object of the present invention is to detect an open phase when a connection failure occurs in any one of the three-phase power lines between the inverter and the compressor. It is an object of the present invention to provide a refrigerator compressor control device and method which can be easily repaired by issuing an alarm.

[0011]

According to a first aspect of the present invention, there is provided a compressor control device for a refrigerator, comprising: a power supply section for supplying power; and a power supply output from the power supply section. 3 through transistor switching
An inverter for converting to a phase power, an inverter driving unit for applying a signal for switching the transistor to the inverter, a compressor using a brushless DC motor driven by a three-phase power output from the inverter, and A back electromotive force applied to each phase of a three-phase power supply line between the inverter and the compressor in a compressor control device for a refrigerator including a position sensing unit for sensing a rotor position and an operation speed of the compressor. And a three-phase power supply between the inverter and the compressor, which receives a phase voltage detection signal output from the phase voltage detection unit and outputs a phase voltage detection signal preset according to the presence or absence of the phase voltage detection signal. It is determined whether or not a connection failure has occurred in any one of the phases in the line, and it is determined that a connection failure has occurred. A control unit that turns off the inverter drive unit to stop driving of the compressor and outputs an alarm signal; and an alarm signal output from the control unit is input so that the connection failure and the three-phase power supply line A display unit for notifying the user of the opened phase.

In addition, a method for controlling a compressor of a refrigerator according to the present invention includes a power supply unit for supplying power, an inverter for converting power output from the power supply unit into a three-phase power supply by switching an internal transistor, and the transistor Drive unit for applying a signal for switching the inverter to the inverter, a compressor using a brushless DC motor driven by a three-phase power supply output from the inverter, a rotor position and an operating speed of the compressor And a phase voltage sensor that outputs a phase voltage detection signal that is preset according to the presence or absence of a back electromotive force applied to each phase of the three-phase power line between the inverter and the compressor. In the compressor control method for a refrigerator, wherein the compressor is initially driven for a certain period of time; Determining whether all of the phase voltage detection signals output from the phase voltage sensing unit are normally output on the three-phase line, and determining whether the phase voltage detection signals are all normal on the three-phase line. If not, turning off the inverter driving unit to stop driving the compressor and displaying a phase line in which an abnormality has occurred is displayed.

[0013]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 2 is a block diagram of a compressor control device for a refrigerator according to the present invention. In operation, if power is supplied to the refrigerator through the power supply unit 15, the supplied power is converted to three-phase power through the inverter 20 and then supplied to the three-phase connection terminal of the compressor 30 so as to be supplied to the compressor 30. Is driven. A position sensing unit 40 for sensing a rotor position of the compressor 30 is connected to a three-phase connection line of the compressor 30, and the position sensing unit 40 is rotated by the back electromotive force of each phase of the compressor 30. The child position detection signal is output to three input terminals A, B, and C of the control unit 50.
Here, the u phase is connected to terminal A, the v phase is connected to terminal B, and the w phase is connected to terminal C.

The inverter driving unit 60 is connected to the control unit 5
A signal for switching the power transistors TR1 to TR6 inside the inverter 20 is applied to the inverter 20 according to the control signal output from 0. Since the initial start control unit 50 of the compressor 30 cannot recognize the rotor position of the compressor 30 during the initial fixed period,
The compressor 30 is forcibly turned on by applying an arbitrary switching signal to the six power transistors TR1 to TR6 inside 0. Such a section is called a step drive section. If the length of the step drive section is long, the parts are damaged and the compressor 30 is adversely affected.

[0015] The phase voltage sensing unit 90 detects each phase (p) of the compressor.
phase; u-phase, v-phase, and w-phase) are output to the input terminals D, E, and F of the control unit 50. The phase voltage sensing unit 90 will be described with reference to FIG. FIG. 3 is a detailed circuit diagram of the phase voltage sensing unit 90 of FIG. For example, when the back electromotive force is input to the u-phase line in each phase line, the phase voltage sensing unit 90 may be configured to receive the back electromotive force from the u phase of the compressor. It includes a transistor TR1 that is turned on, and a photocoupler PC1 that is turned off and outputs a high signal when the transistor TR1 is turned on, and is turned on and outputs a low signal when the transistor TR1 is turned off.

In operation, the back electromotive force input from the u phase of the compressor 30 is reduced in pressure through the resistor R2 of the phase voltage sensing unit 90, and then input to the base terminal of the transistor TR1. Turned on. Thereby, the photodiode of the photocoupler PC1 is turned off, and the phototransistor is also turned off. When the phototransistor is turned off, a high signal is output to the input terminal D of the control unit 50.

On the other hand, if no back electromotive force is input to the u phase, the transistor TR1 is turned off and the photocoupler PC
1 is turned on. Therefore, a low signal is output to the input terminal D of the control unit. In other words, a pulse signal is generated on the u-phase line according to the back electromotive force of the compressor
Output to 0. At this time, the controller 50 determines the phase voltage of the compressor 30 based on the pulse signal.

That is, if a high signal and a low signal are alternately continuously input from the u-phase line of the phase voltage sensing unit 90, the control unit 50 determines that the corresponding phase line is normally connected, If the low signal is continuously input, it is determined that the corresponding phase line is not connected. In the above, only the u phase has been described, but the remaining phases (v
Phase, w phase) operate in the same manner, and the v phase
And the w-phase is connected to the terminal F of the control unit 50.

Hereinafter, a method for controlling a compressor of a refrigerator according to the present invention will be described in detail with reference to FIG. FIG. 4 shows a method for controlling a compressor of a refrigerator according to the present invention. When the driving condition of the compressor 30 is satisfied, the control unit 50
An arbitrary switching signal is applied to the inverter 20 through the controller to drive the compressor 30 stepwise for a predetermined time (5 seconds) (S10). That is, in the step (S10), the control unit 50 generates a three-phase power from the inverter 20 by generating an arbitrary pulse waveform in the inverter driving unit 60 to detect the rotor position of the compressor 30. The voltage is applied to the compressor 30.

At this time, the position sensing unit 40 senses the back electromotive force of each phase of the compressor 30 and the control unit 50 determines the rotor position and the number of revolutions during the step driving period. Detects the back electromotive force of each phase and outputs a phase voltage detection signal to the control unit 50. The control unit 50 determines whether the phase voltage detection signal from the phase voltage detection unit 90 is normally output on the three-phase line. A decision is made (S30).

If any one of the phases of the compressor 30 connected to the inverter 20 is open, no phase voltage is generated in that phase and the corresponding transistor of the phase voltage sensing unit 90 Is turned off to maintain that state, the photodiode of the corresponding photocoupler is turned on to emit light, and the phototransistor is turned on by the light emission of the photodiode.

As a result, a low signal is output to the control unit 50, but if the low signal is continuously input from the phase voltage sensing unit 90, the control unit 50 opens the connection between the inverter 20 and the compressor 30. In order to protect the compressor 30 from unreasonable driving, the transistor switching signal inside the inverter 20 is cut off (S32).
The compressor 30 is stopped (S34). Thereafter, the control unit 50
Drives the alarm unit 80 to warn of an abnormal state of the compressor 30 and to notify the user of the opened phase (S36).

On the other hand, if it is determined in the step (S30) that the phase voltage detection signals from the phase voltage sensing unit 90 are all properly output on the three-phase line, the control unit 50 operates the compressor 30 normally (step S30). S40). That is, the control unit 50 determines the position of the rotor based on a signal output from the position sensing unit 40 to normally operate the compressor 30, controls the inverter driving unit 60, and controls the transistor TR 1 of the inverter 20.
A -TR6 switching signal is generated, and a three-phase power is generated by the inverter 20 and applied to the compressor 30.
With this three-phase power supply, the compressor 30 rises to the set rotation speed and operates normally.

Here, the normal operation means that the compressor 30 is started by the step drive and is operated at the set rotation speed. When the compressor 30 operates normally,
The control unit 50 controls the compressor 30 input from the position sensing unit 40.
The amount of change in the number of revolutions of the compressor 30 is sensed based on the rotor position information (S50), and it is determined whether the detected amount of change in the number of revolutions exceeds a preset reference amount of change (S60).

If it is determined in step (S60) that the change in the rotation speed of the compressor 30 is less than the reference change amount, the control unit 50 operates the compressor 30 normally without a large change in the rotation speed. However, if the change amount of the rotation speed of the compressor 30 exceeds the reference change amount, the control unit 50 increases the number of times of error detection by one (S70) and determines whether the preset reference time has been exceeded. A determination is made (S80). At this time, the reference time is set to about 30 seconds-1 minute.

If it is determined in step S80 that the reference time has been exceeded, the controller 50 determines whether the number of error detections is three (S90). If the number of error detections is three or more in step S90, the control unit 50 determines that the compressor 30 has an abnormality and shuts off the transistor switching signal inside the inverter 20 (S10).
0) The compressor 30 is stopped (S110). Compressor 30
Is stopped, the control unit 50 clears the number of times of error detection (S120), and drives the alarm unit 80 to notify the user of the abnormality of the compressor 30 (S130).

[0027]

As described above, according to the compressor control apparatus and method for a refrigerator according to the present invention, the three-phase power supply line supplied to the compressor from the inverter that drives the compressor using the brushless DC motor. If any one of the phases is opened or the rotation speed of the compressor exceeds the critical value within a predetermined time, the compressor is stopped to protect the inverter and compressor, and the opened phase is There is an effect that repair can be easily performed by sensing and alarming.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional compressor control device for a refrigerator.

FIG. 2 is a block diagram of a compressor control device for a refrigerator according to the present invention.

FIG. 3 is a detailed circuit diagram of a phase voltage detector of FIG. 2;

FIG. 4 illustrates a compressor control method for a refrigerator according to the present invention.

[Explanation of symbols]

 15 Power supply unit 20 Inverter 30 Compressor 40 Position sensing unit 50 Control unit 60 Inverter driving unit 80 Display unit 90 Phase voltage sensing unit TR1-TR6 Power transistor

Claims (7)

[Claims] A power supply unit for supplying power; an inverter for converting power output from the power supply unit into a three-phase power supply through switching of an internal transistor; and a signal for switching the transistor applied to the inverter. A refrigerator using an inverter driving unit, a compressor using a brushless DC motor driven by a three-phase power output from the inverter, and a position sensing unit for sensing a rotor position and an operating speed of the compressor. In the compressor control device, a phase voltage detection unit that outputs a phase voltage detection signal preset according to the presence or absence of a back electromotive force applied to each phase of a three-phase power line between the inverter and the compressor; A phase voltage detection signal output from a phase voltage sensing unit is input, and a three-phase power supply between the inverter and the compressor is connected. It is determined whether a connection failure has occurred in any one of the phases, and if it is determined that a connection failure has occurred, the inverter drive unit is turned off to stop driving the compressor. A control unit that outputs a warning signal, and a display unit that receives a warning signal output from the control unit and informs a user of the connection failure and a phase opened in the three-phase power line. A compressor control device for a refrigerator. 2. The phase voltage sensing unit outputs a high signal to the control unit when a back electromotive force is input to each phase of the three-phase power supply line of the compressor, and outputs a low signal when no back electromotive force is input. The compressor control device for a refrigerator according to claim 1, wherein a signal is output to the control unit. 3. The phase voltage sensing unit includes: a transistor that is turned on when a back electromotive force is input from each phase of the compressor; and a high signal that is turned off when the transistor is turned on. The compressor control device for a refrigerator according to claim 1, further comprising a photocoupler that outputs a low signal when the transistor is turned off. 4. The control unit, if a high signal and a low signal are sequentially and alternately input from each phase line of the phase voltage sensing unit, determines that the corresponding phase line is normally connected, and 3. The apparatus according to claim 2, wherein if the signal is continuously input, it is determined that the corresponding phase line is not connected. 5. A power supply for supplying power, an inverter for converting power output from the power supply to a three-phase power through switching of an internal transistor, and applying a signal for switching the transistor to the inverter. An inverter driving unit, a compressor using a brushless DC motor driven by a three-phase power output from the inverter, a position sensing unit for sensing a rotor position and an operating speed of the compressor, and the inverter and the inverter A method for controlling a compressor of a refrigerator, comprising: a phase voltage sensing unit that outputs a phase voltage detection signal that is preset according to the presence or absence of a back electromotive force applied to each phase of a three-phase power line between the compressor and the compressor. Initial driving for a certain period of time, and if a certain period of time has passed in the step, the phase voltage sensing unit outputs Determining whether all the phase voltage detection signals are normally output on the three-phase line. If the phase voltage detection signals are not all normally output on the three-phase line, turning off the inverter driving unit and Stopping the operation of the compressor and displaying a phase line in which an abnormality has occurred. 6. The step of judging whether all of the phase voltage detection signals are normally output on the three-phase line is performed by alternately continuously outputting a high signal and a low signal on each of the three phase lines of the phase voltage sensing unit. If so, it is determined that the normal state is detected, and if a low signal is continuously output on at least one of the three phase lines, it is determined that the corresponding phase line is open and abnormal. Item 6. A method for controlling a compressor of a refrigerator according to Item 5. 7. If the phase voltage detection signals are all normally output on the three-phase line, the compressor is driven normally, and a change in the number of revolutions of the compressor is sensed based on an output signal of the position sensing unit. Determining whether the sensed rotation speed change amount exceeds a predetermined reference change amount; and wherein the rotation speed change amount exceeds the reference change amount, and the number of times the rotation speed change amount exceeds a predetermined number of times during a certain period of time. The method according to claim 5, further comprising the step of stopping the driving of the compressor.