JP2000197385A - Method and apparatus for detecting lock in compressor driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect locking of a DC brushless motor attributed to malfunction of a compressor upon occurrence of incomplete start. SOLUTION: A lock detector comprises a first frequency detecting section 11 receiving the current of any one phase of a DC brushless motor and detecting the frequency of current waveform, a second frequency detecting section 12 receiving the potential difference between the neutral potential of the stator winding of the DC brushless motor and the neutral potential of a resistor connected in parallel with the stator winding and detecting the frequency of the potential difference, a frequency deciding section 13 receiving both frequencies and making a decision whether the frequency of the potential difference is equal to three times that of the current waveform, and a state deciding section 14 for making a decision that the motor is not locked in response to a decision that the frequency of the potential difference is equal to three times that of the current waveform otherwise making a decision that the motor is locked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting lock in a compressor drive, and more particularly, to a brushless D controlled by an inverter.
The present invention relates to a method and an apparatus for detecting a lock state of a brushless DC motor in an apparatus for driving a compressor by a C motor.

[0002]

2. Description of the Related Art Conventionally, a device for driving a compressor by a brushless DC motor controlled by an inverter has been proposed. Such a compressor driving device detects the magnetic pole position of the rotor of the brushless DC motor, generates a position signal, and controls the output waveform of the inverter based on the position signal to stably operate the brushless DC motor. The compressor is driven by this brushless DC motor.

[0003] Therefore, in a normal state, the compressor can be driven stably by the brushless DC motor.

[0004]

However, when the brushless DC motor is locked in such a compressor drive device, the brushless DC motor burns out if the operation for the operation is continued as it is. . Further, at the installation site of the compressor, a start-up failure of the brushless DC motor occurs.

In such a case, at the installation site,
It has not been possible to clearly identify whether the lock of the brushless DC motor is caused by a failure of a mechanical part of the compressor or a failure of an inverter that drives the brushless DC motor. Therefore, if the brushless DC motor fails to start at the installation site, a method of replacing the compressor or the electrical components at the site will be adopted, which will require a remarkably large cost for the failure countermeasures and start-up. There is a disadvantage that it takes an extremely long time to elucidate the cause of the failure.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to easily determine that a lock of a brushless DC motor caused by a failure of a compressor has occurred when a start failure occurs. It is an object of the present invention to provide a lock detection method and a lock detection device in a compressor drive device capable of detecting the lock.

[0007]

According to a first aspect of the present invention, there is provided a lock detecting method for a compressor driving apparatus, comprising: a system for driving a compressor by a brushless DC motor controlled by an inverter; Detects the potential difference between the neutral point potential and the neutral point potential of the resistor connected in parallel with the stator winding, and locks the brushless DC motor due to compressor failure based on the detected potential difference This is a way to detect that

According to a second aspect of the present invention, there is provided a lock detecting method for detecting a lock of a brushless DC motor caused by a compressor failure based on a cycle of a detected difference potential. .

According to a third aspect of the present invention, there is provided a lock detecting method for a compressor driving apparatus, wherein the frequency of the detected difference potential is a brushless D.
This method detects that the brushless DC motor is locked due to a compressor failure in response to a frequency other than three times the operating frequency of the C motor.

According to a fourth aspect of the present invention, there is provided a lock detecting device for a compressor driving device, wherein
In a system in which a compressor is driven by a C motor,
A differential potential detecting means for detecting a potential difference between a neutral point potential of a stator winding of the brushless DC motor and a neutral point potential of a resistor connected in parallel with the stator winding; And a lock determining means for determining whether or not the brushless DC motor is locked due to the compressor failure based on the difference potential obtained.

According to a fifth aspect of the present invention, there is provided a lock detecting device in the compressor driving device, wherein the lock determining means determines whether or not the brushless DC motor has been locked due to a compressor failure based on a cycle of the detected difference potential. That which determines whether or not is adopted.

According to a sixth aspect of the present invention, in the lock detecting device of the compressor driving device, the frequency of the detected difference potential is three times the operating frequency of the brushless DC motor.
A method that determines whether or not the frequency is other than three times, and determines that the brushless DC motor is locked due to a compressor failure in response to the frequency being other than three times. It is.

According to a seventh aspect of the present invention, in the lock detecting device of the compressor driving device, the lock determining means determines whether or not the brushless DC motor is locked due to a compressor failure based on the detected difference potential amplitude. That which determines whether or not is adopted.

The lock detecting device in the compressor driving device according to claim 8 employs a brushless DC motor having a rotor provided with a permanent magnet embedded therein.

[0015]

According to the lock detecting method in the compressor driving device of the present invention, when the compressor is driven by the brushless DC motor controlled by the inverter, the neutral point potential of the stator winding of the brushless DC motor and Detects the potential difference between the neutral point potential of the resistor connected in parallel with the stator winding, and based on the detected potential difference, determines that lock of the brushless DC motor due to compressor failure has occurred. Because it detects, if a startup failure occurs at the installation site without adding a special detection circuit,
It is possible to easily identify whether the cause is a failure of the mechanical part of the compressor, and it is possible to shorten the time required for elucidating the cause of the start failure and to reduce the cost of the measure for the failure. . Further, burning of the brushless DC motor and burning of the inverter element can be prevented beforehand.

According to the lock detecting method in the compressor driving device of the present invention, it is detected that the brushless DC motor is locked due to the compressor failure based on the cycle of the detected difference potential. Therefore, by detecting the period of the difference potential, the same operation as the first aspect can be achieved.

According to the lock detecting method of the compressor driving device of the third aspect, the compressor failure is detected in response to the frequency of the detected difference potential being a frequency other than three times the operating frequency of the brushless DC motor. Brushless DC caused by
Detecting that the motor is locked, detecting the frequency of the difference potential,
The same operation as described above can be achieved.

According to the lock detecting device in the compressor driving device of the fourth aspect, when the compressor is driven by the brushless DC motor controlled by the inverter,
The difference potential detection means detects the difference potential between the neutral point potential of the stator winding of the brushless DC motor and the neutral point potential of a resistor connected in parallel with the stator winding, and the lock determination means Based on the difference potential detected by the difference potential detecting means, it can be determined whether or not the lock of the brushless DC motor due to the compressor failure has occurred.

Therefore, if a start-up failure occurs at the installation site without adding a special detection circuit,
It is possible to easily identify whether the cause is a failure of the mechanical part of the compressor, and it is possible to shorten the time required for elucidating the cause of the start failure and to reduce the cost of the measure for the failure. . Further, burning of the brushless DC motor and burning of the inverter element can be prevented beforehand.

According to a fifth aspect of the present invention, there is provided a lock detecting device in the compressor driving device, wherein the lock determining means determines that the brushless DC motor is locked due to a compressor failure based on the cycle of the detected difference potential. Therefore, the same operation as in claim 4 can be achieved by detecting the period of the difference potential.

In the lock detecting device of the compressor driving device according to the present invention, the lock determining means determines whether or not the frequency of the detected difference potential is a frequency other than three times the operating frequency of the brushless DC motor. , And in response to the frequency being other than three times, it is determined that the lock of the brushless DC motor has occurred due to the compressor failure. Therefore, the frequency of the difference potential is detected. By doing so, the same operation as the fourth aspect can be achieved.

In the lock detecting device of the compressor driving device according to the present invention, the lock determining means may lock the brushless DC motor due to the compressor failure based on the amplitude of the detected difference potential. Therefore, the same operation as that of claim 4 can be achieved by detecting the amplitude of the difference potential.

In the lock detecting device in the compressor driving device according to the present invention, the brushless DC motor may be
Since a rotor having a rotor provided with a permanent magnet embedded therein is employed, in addition to the function of any one of claims 4 to 7, not only the motor torque but also the motor torque when lock is not generated. The compressor can be efficiently driven using the reluctance torque.

[0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a lock detecting method in a compressor driving apparatus according to an embodiment of the present invention;

FIG. 1 is a schematic diagram showing one embodiment of a compressor driving device.

The compressor driving apparatus supplies an output from an inverter 2 having a DC power supply 1 as an input to stator windings 3 u, 3 v, and 3 w of a brushless DC motor 3 connected in a Y direction. Is directly or indirectly connected to the rotating shaft of the compressor 4. And
Stator windings 3u, 3v, 3w of brushless DC motor 3
Resistors 5u, 5v, and 5w are connected in Y in parallel with each other, and a neutral point potential of the stator windings 3u, 3v, and 3w of the brushless DC motor 3 and a neutral point potential of the resistors 5u, 5v, and 5w are used as a low-pass filter. The difference potential is supplied to a functioning operational amplifier 6 to obtain a difference potential, and the obtained difference potential is supplied to an operation amplifier 7 functioning as a comparator to obtain a position detection signal which rises or falls at a zero crossing of the difference potential, and obtains the obtained position. The detection signal is supplied to an inverter control unit 8 composed of a one-chip microcomputer or the like to generate an inverter waveform control signal that switches at each rising and falling of the position detection signal,
The generated inverter waveform control signal is supplied to the inverter 2 via a driver (not shown). In addition, the inverter control unit 8 has a function of detecting whether or not the locked state is received by using the difference potential as an input.

FIG. 2 is a diagram schematically showing the configuration of a brushless DC motor having a surface magnet structure, in which a permanent magnet 3b is mounted at a predetermined position on the surface of a rotor 3a. The stator 3c has a number of slots 3d around which a stator winding (not shown) is wound. The d-axis indicated by an arrow in the drawing is an axis indicating the direction of the magnetic flux generated by the permanent magnet 3b, and the q-axis is an axis electrically shifted from the d-axis by 90 °.

FIG. 3 is a diagram schematically showing the configuration of a brushless DC motor having an embedded magnet structure, in which a permanent magnet 3f is mounted without being exposed on the surface of a rotor 3e. However, a nonmagnetic material 3g is mounted between the adjacent permanent magnets 3f to prevent a magnetic flux short circuit between the adjacent permanent magnets 3f. The configuration of the stator 3c is the same as that of the brushless DC motor of FIG.

FIG. 4 is a flow chart for explaining a process for judging whether or not a locked state has occurred in the compressor driving device having the structure shown in FIG. Note that the processing of this flowchart is performed for each rise and fall of the position detection signal.

At step SP1, it is determined whether or not there is an operation request, and if it is determined that there is no operation request, a series of processing ends. Conversely, when it is determined that there is a driving request, it is determined in step SP2 whether switching to the position detection driving is permitted.

If it is determined in step SP2 that the switching to the position detection operation (operation for controlling the inverter output waveform based on the position detection signal) is permitted, the position detection operation is performed in step SP3. In step SP4, it is determined whether or not the position detection operation completed flag indicating that the switching to the position detection operation has already been performed is set, and it is determined that the position detection operation completed flag is set. If so, the series of processing ends. Conversely, when it is determined in step SP4 that the position detection operation completed flag is not set, in step SP5, the position detection operation completed flag is set, and in step SP6, the lock state flag is cleared. The series of processing ends as it is.

If it is determined in step SP2 that switching to the position detection operation is not permitted, it is determined in step SP7 whether or not counting of the number of interrupts based on the position detection signal is permitted. If not, the series of processing ends.
Conversely, if it is determined in step SP7 that counting of the number of interrupts based on the position detection signal is permitted, in step SP8, the number of interrupts based on the position detection signal is incremented, and the series of processing ends as it is. .

FIG. 5 is a flowchart for explaining the interrupt processing for each carrier cycle in the inverter control unit.

At step SP1, it is determined whether or not there is an operation request, and if it is determined that there is no operation request, a series of processing ends. Conversely, if it is determined that there is a driving request, it is determined in step SP2 whether switching to the position detection operation has been completed, and it is determined that switching to the position detection operation has been completed. In step SP3, a position detection operation is performed.
Conversely, when it is determined that the switching to the position detection operation has not been completed, the synchronous operation is performed in step SP4. Then, after the processing of step SP3 or the processing of step SP4 is performed, the series of processing ends.

FIG. 6 is a flowchart for explaining the processing in step SP4 of FIG.

In step SP1, it is determined whether or not it is the operation mode update timing. If it is determined that the operation mode is to be updated, step SP
In step 2, a lock determination process is performed. In step SP3, the operation mode is updated. In step SP4, it is determined whether the acceleration of the brushless DC motor has ended. If it is determined that the acceleration has ended, In step SP5, a determination process for switching to the position detection operation is performed.

If it is determined in step SP1 that it is not the update timing of the operation mode, if it is determined in step SP4 that the acceleration is not completed, or if the processing in step SP5 is performed, In SP6, a process of outputting a waveform corresponding to the corresponding operation mode is performed, and the series of processes ends as it is.

FIG. 7 is a flowchart for explaining the processing in step SP2 of FIG.

In step SP1, it is determined whether or not the number of output waveform cycles indicating the difference potential is equal to the first predetermined number n0. If they are equal, in step SP2, interruption by the position detection signal is permitted, and Is completed.

If it is determined in step SP1 that the number of output waveform cycles such as a current waveform is not equal to the first predetermined number n0, then in step SP3, the number of output waveform cycles is changed to the second predetermined number (n0 + n1). ) Is determined, and if they are equal to each other, in step SP4, counting of the number of interrupts based on the position detection signal is permitted, and the series of processing is terminated as it is.

If it is determined in step SP3 that the number of output waveform cycles is not equal to the second predetermined number (n0 + n1), then in step SP5, the number of output waveform cycles is equal to the third predetermined number (n0 + n1 + n2). It is determined whether or not they are equal, and if they are equal, in step SP6, it is determined whether or not the number of interrupts based on the position detection signal is equal to or more than 2 (n2-n1) and equal to or less than {3 (n2-n1) -1}. , The number of interrupts based on the position detection signal is 2 (n2-n
If not less than 1) and not more than {3 (n2-n1) -1}, in step SP7, a lock state flag indicating a lock state is set, and the series of processing ends as it is. Conversely, the number of interrupts based on the position detection signal is 2 (n2-n1) or more and {3 (n2-n1) -1}
If it is determined that it is not less than the above, the series of processing ends.

If it is determined in step SP5 that the number of output waveform periods is not equal to the third predetermined number (n0 + n1 + n2), in step SP8, the number of output waveform periods is reduced to the third predetermined number (n0 + n1 + n2). It is determined whether or not the value is equal to the value incremented by one. If they are equal, the number of interrupts based on the position detection signal is less than {2 (n2 + 1-n1) -a1} or {2 (n2 + 1-n1) + b} in step SP9. It is determined whether or not a1 is greater than 0 and a1 is 0 or more and 2 (n2 + 1-n
1), b is 0 or more}, and the number of interrupts based on the position detection signal is less than {2 (n2 + 1-n1) -a1} or {2
If it is determined that the value is larger than (n2 + 1-n1) + b}, in step SP10, the lock state flag is cleared, and the series of processing ends. Conversely, the number of interrupts based on the position detection signal is $ 2 (n2 + 1-n
1) less than -a1} or {2 (n2 + 1-n1) + b}
If it is determined that neither is greater than
The series of processing ends as it is.

If it is determined in step SP8 that the number of output waveform periods is not equal to the third predetermined number (n0 + n1 + n2) incremented by 1, the number of output waveform periods is increased to the fourth predetermined number (n0 + n1 + n2). n0 + n1 + n2 + n
Until the value reaches 3), it is determined whether or not it is equal to the sequentially incremented value, and the same processing as in step SP9 and step SP10 is performed according to the determination result.

Then, in step SP11, the number of output waveform periods is equal to the fourth predetermined number (n0 + n1 + n2 + n).
It is determined whether or not it is equal to 3).
In P12, the number of interrupts based on the position detection signal is less than {2 (n2 + n3-n1) -an3} or {2
(N2 + n3-n1) + b}, where an3 is 0 or more and 2 (n2 + n3-n)
1) Less than #, the number of interrupts based on the position detection signal is $ 2
(N2 + n3-n1) -an3} or less than {2 (n2
+ N3-n1) + b}, the lock state flag is cleared in step SP13. Then, in step SP12, the number of interrupts based on the position detection signal is $ 2 (n2 + n3-n1)-
If it is determined that none of these is less than an3} or greater than {2 (n2 + n3-n1) + b}, or if the processing in step SP13 is performed, an interrupt based on the position detection signal is made in step SP14. The counting of the number is not permitted, and in step SP15, the interruption by the position detection signal is not permitted, and the series of processing ends.

Also, if it is determined in step SP11 that the number of output waveform periods is not equal to the fourth predetermined number (n0 + n1 + n2 + n3), the series of processing ends.

In the processing of the above-mentioned flowchart, for example, empirically determined values are adopted as the values of n0, n1, n2, and n3.

In summary, when the output waveform such as the current waveform has passed n0 cycles after the start, the interrupt based on the position detection signal is permitted, and after the output waveform (n0 + n1) cycles, the number of interrupts based on the position detection signal is enabled. After the output waveform (n0 + n1 + n2) cycles, the number of interrupts based on the position detection signal is 2 (n2-n1) or more and $ 3
If not more than (n2-n1) -1}, the lock state flag is set.

Then, the output waveform (n0 + n1 + n2 +
1) After the cycle, until (n0 + n1 + n2 + n3) cycle,
The number of interrupts based on the position detection signal is compared with a predetermined threshold value at an arbitrary period, and if the locked state is not determined, the locked state flag is cleared.

At the period of the output waveform (n0 + n1 + n2 + n3), after determining whether or not the lock state is established, the number of interrupts based on the position detection signal and the interrupt based on the position detection signal are disabled.

The lock state flag is also cleared when switching from the synchronous operation to the position detection operation is normally performed.

Therefore, when the lock state flag remains set, it is possible to detect that the lock is caused by a mechanical part failure of the compressor.

This will be described in more detail.

When the rotor is rotating normally, the difference potential between the neutral point potential of the stator winding and the neutral point potential of a resistor connected in parallel with the stator winding is equal to 3 of the fundamental wave. It is known to occur at twice the frequency.

However, when the brushless DC motor is locked, no back electromotive force is generated. In the case of the brushless DC motor having the embedded magnet structure shown in FIG. 3, the rotor has a salient pole structure. It is considered that the difference potential fluctuates twice in one cycle of the current waveform.

On the other hand, in the case of the brushless DC motor having the surface magnet structure shown in FIG. 2, since the rotor does not have a salient pole structure, it is considered that the difference potential does not fluctuate.

Therefore, the fact that the potential difference is different between the unlocked state where the rotor is rotating normally and the locked state where the rotor is not rotating normally is used to determine that the locked state is established. Probably detectable.

Specifically, when the brushless DC motor having the embedded magnet structure shown in FIG. 3 is operating normally, the current waveform and the difference potential waveform are shown in FIGS. 8A and 8B, respectively. As shown, the frequency of the difference potential is three times the frequency of the current waveform. On the other hand, when a startup failure occurs due to the lock state, the current waveform and the waveform of the difference potential are as shown in FIGS. 9A and 9B, respectively, and the frequency of the difference potential is It is twice the frequency of the current waveform. When the locked state occurs other than at the time of startup, the current waveform and the waveform of the difference potential are as shown in FIGS. 10A and 10B, respectively, and the frequency of the difference potential is equal to the frequency of the current waveform. Doubled.

Therefore, if the frequency of the difference potential is three times the frequency of the current waveform, the state is unlocked. If the frequency of the difference potential is twice the frequency of the current waveform, the state is locked.

When the brushless DC motor having the surface magnet structure shown in FIG. 2 is operating normally, the current waveform and the waveform of the difference potential are as shown in FIGS. , The frequency of the difference potential is 3 of the frequency of the current waveform.
Doubled. On the other hand, when the lock state occurs, the current waveform and the waveform of the difference potential are respectively shown in FIG.
As shown in the middle (A) and (B), the difference potential is almost zero.

Therefore, when the frequency of the difference potential is three times the frequency of the current waveform, the circuit is in the unlocked state, and when the difference potential is almost 0, the circuit is in the locked state.

FIG. 13 is a flowchart for explaining another embodiment of the lock detecting method of the present invention. The process of this flowchart is performed for each determination process of switching to the position detection operation.

In step SP1, the synchronous operation is started. In step SP2, the difference between the neutral point potential of the stator winding of the brushless DC motor and the neutral point potential of the resistor connected in parallel with the stator winding. The potential (position signal) voltage is detected, and in step SP3, it is determined whether or not the detected voltage is higher than the previously detected voltage.

If it is determined that the detected voltage is higher than the previously detected voltage, the process proceeds to step SP
In step 4, the voltage of the position signal is detected, and step SP5
In, it is determined whether or not the detected voltage is higher than the previously detected voltage. Conversely, if it is determined that the detected voltage is not higher than the previously detected voltage, the voltage of the position signal is detected in step SP6, and the detected voltage is detected in step SP7. It is determined whether the voltage is higher than the voltage. And
If it is determined in step SP5 that the voltage detected is higher than the previously detected voltage, or if it is determined in step SP7 that the voltage detected is not higher than the previously detected voltage, step SP8 is performed.
, The lock possibility flag is turned ON, and conversely, if it is determined that the voltage detected in step SP5 is not higher than the voltage detected last time, or if the voltage detected in step SP7 is the voltage detected previously. If it is determined that the value is larger than the threshold value, the lock possibility flag is turned off in step SP9. Note that the processing from step SP4 to step SP9 is performed M times (however,
(M is an integer of 3 or more).

When the processing in step SP8 or the processing in step SP9 is performed, the processing in step SP8 is performed.
In 10, the process of determining the switching to the position detection operation (for example, the process of permitting the switching to the position detection operation when the maximum value of the amplitude of each cycle of the difference potential exceeds a predetermined threshold and is stable) Is determined in step SP11, and a series of processes is terminated as it is. The determination as to whether or not the lock state is established may be made based on, for example, whether or not the lock possibility flag is continuously ON N times (where N is an integer smaller than M). When the flag is ON continuously N times, it is determined that the lock state is established.

Specifically, comparing FIG. 8 (B), FIG. 9 (B), and FIG. 10 (B), the brushless DC motor having the embedded magnet structure shown in FIG. 3 operates normally. It can be seen that the maximum value of the amplitude of the differential potential is constant in each cycle when the current state is present, whereas the maximum value of the amplitude of the differential potential increases and decreases every other cycle in the locked state. Therefore, when the lock state is established, the lock possibility flag is continuously turned ON N times by performing the processing of the flowchart in FIG. 13, and when the lock state is not locked, the lock possibility flag is turned ON. , OFF, so that it can be reliably determined whether or not the vehicle is in the locked state.

Further, in the case of the brushless DC motor having the surface magnet structure shown in FIG. 2, as is apparent from comparison between FIG. 11B and FIG. The maximum value of the amplitude of the difference potential is constant in each cycle, while in the locked state,
It can be seen that the difference potential becomes almost zero. Therefore, when using a brushless DC motor having a surface magnet structure,
The lock state can be detected by detecting that the difference potential is substantially zero.

FIG. 14 is a block diagram showing an embodiment of the lock detecting device in the compressor driving device according to the present invention.

The lock detecting device includes a first frequency detecting section 11 which receives a current of any phase of the brushless DC motor 3 and detects a frequency of a current waveform;
A second frequency detection unit 12 that receives a difference potential between a neutral point potential of a stator winding of the motor 3 and a neutral point potential of a resistor connected in parallel with the stator winding and detects a frequency of the difference potential; With both frequencies as inputs, a frequency determination unit 13 that determines whether the frequency of the difference potential is three times or other than three times the frequency of the current waveform. The frequency determination unit 13 determines that the frequency of the difference potential is three times the frequency of the current waveform. In response to the determination that there is, the locked state is determined in response to the frequency determination unit 13 determining that the frequency of the difference potential is other than three times the frequency of the current waveform. And a state determination unit 14 that determines that

When the lock detecting device having the above configuration is employed, the frequency of the difference potential is three times or three times the frequency of the current waveform.
It is possible to determine the unlocked state or the locked state based on whether it is other than double.

FIG. 15 is a block diagram showing another embodiment of the lock detecting device in the compressor driving device according to the present invention.

This lock detecting device receives the difference potential between the neutral point potential of the stator winding of the brushless DC motor 3 and the neutral point potential of a resistor connected in parallel with the stator winding and receives the difference potential of 1 An amplitude maximum value detection unit 21 for detecting the maximum value of the amplitude for each cycle, a first determination unit 22 for determining whether or not the detected maximum value of the amplitude is substantially 0, and a maximum value of the detected amplitude And a second determination unit 23 that determines whether or not the amplitude changes every other cycle, and the first determination unit 22 determines that the detected maximum value of the amplitude is not substantially zero, and the second determination unit 23, it is determined that the state is the unlocked state in response to the determination that the detected maximum value of the amplitude does not involve a change in magnitude every other cycle, and the first determination unit 22 determines the detected amplitude. Is determined to be almost 0, or the second determination unit 23 More, the maximum value of the detected amplitude and a determining state determining unit 24 that the locked state in response to the determination that involves a change in magnitude in one period apart.

When the lock detecting device having the above configuration is employed, it is determined whether the maximum value of the amplitude of the difference potential in each cycle is substantially zero or the maximum value of the amplitude of the difference potential in each cycle is one cycle. It is possible to determine whether the state is the unlocked state or the locked state based on whether or not every change involves a change in magnitude.

Of course, since it is known in advance whether the brushless DC motor to be used has a surface magnet structure or an embedded magnet structure, one of the first determination unit 22 and the second determination unit 23 is omitted. It is possible to

If it is determined in any of the above embodiments that the lock state is established, a lock has occurred due to an abnormality in the mechanical part of the compressor. Conversely, in any of the above embodiments, Is not determined to be in the locked state and the brushless DC motor cannot be operated,
This is due to inverter failure. Therefore, the reason why the brushless DC motor cannot be operated easily and in a short time even at the installation site can be clarified. As a result, it is possible to reduce the cost of the defect countermeasure. Needless to say, the time required to elucidate the cause can be shortened, so that a large current does not flow for a long time, and burning of the brushless DC motor and burning of the inverter element can be prevented.

[0075]

According to the first aspect of the present invention, it is possible to simply determine whether or not a mechanical part of a compressor is defective when a start-up failure occurs at an installation site without adding a special detection circuit. It is possible to identify and reduce the time required to elucidate the cause of start-up failure, reduce the cost of failure measures, and prevent burnout of the brushless DC motor and inverter element. It has a specific effect that it can be performed.

According to the second aspect of the invention, the same effect as that of the first aspect is obtained by detecting the period of the difference potential.

According to the third aspect of the invention, the same effect as that of the first aspect is obtained by detecting the frequency of the difference potential.

According to a fourth aspect of the present invention, if a start-up failure occurs at an installation site without adding a special detection circuit, it is easily identified whether or not the failure is caused by a failure in the mechanical part of the compressor. It is possible to shorten the time required to elucidate the cause of the start failure, reduce the cost of measures for the failure, and prevent the burnout of the brushless DC motor and the burnout of the inverter element. It has a unique effect that it can be performed.

According to the fifth aspect of the invention, the same effect as that of the fourth aspect is obtained by detecting the cycle of the difference potential.

The sixth aspect of the invention has the same effect as the fourth aspect by detecting the frequency of the difference potential.

The seventh aspect of the invention has the same effect as the fourth aspect by detecting the amplitude of the difference potential.

The invention according to claim 8 is the invention according to claims 4 to 7.
In addition to any of the effects described above, when the lock is not generated, a unique effect that the compressor can be efficiently driven by using not only the motor torque but also the reluctance torque is exerted.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of a compressor driving device.

FIG. 2 is a diagram schematically showing a configuration of a brushless DC motor having a surface magnet structure.

FIG. 3 is a diagram schematically showing a configuration of a brushless DC motor having an embedded magnet structure.

FIG. 4 is a flowchart illustrating a process of determining whether or not a locked state has occurred in the compressor drive device having the configuration of FIG. 1;

FIG. 5 is a flowchart illustrating an interrupt process for each carrier cycle in an inverter control unit.

FIG. 6 is a flowchart illustrating a process of step SP4 in FIG. 5;

FIG. 7 is a flowchart illustrating a process of step SP2 in FIG. 6;

8 is a diagram showing a current waveform and a differential potential waveform when the brushless DC motor having the embedded magnet structure shown in FIG. 3 is operating normally.

9 is a diagram showing a current waveform and a waveform of a potential difference when a start-up failure due to a locked state occurs in the brushless DC motor having the embedded magnet structure shown in FIG.

10 is a diagram showing a current waveform and a waveform of a difference potential when a lock state occurs other than at the time of starting the brushless DC motor having the embedded magnet structure shown in FIG. 3;

11 is a diagram showing a current waveform and a difference potential waveform when the brushless DC motor having the surface magnet structure shown in FIG. 2 is operating normally.

12 is a diagram showing a current waveform and a differential potential waveform when a lock state occurs in the brushless DC motor having the surface magnet structure shown in FIG. 2;

FIG. 13 is a flowchart illustrating another embodiment of the lock detection method of the present invention.

FIG. 14 is a block diagram showing one embodiment of a lock detection device in the compressor drive device of the present invention.

FIG. 15 is a block diagram showing another embodiment of the lock detecting device in the compressor driving device of the present invention.

[Explanation of symbols]

2 Inverter 3 Brushless DC motor 3e Rotor 3f Permanent magnet 3u, 3v, 3w Stator winding 4 Compressor 5u, 5v, 5w Resistance 6 Operational amplifier functioning as low-pass filter 8 Inverter control unit 14, 24 State determination unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomohiro Taniguchi 1000, Otani, Okamotocho, Kusatsu-shi, Shiga 2 Daikin Industries, Ltd. (72) Masakazu Kato 1,000, Otani, Okamotocho, Kusatsu-shi, Shiga 2 Daikin Industries, Ltd. F term (reference) 5H019 CC03 CC09 DD01 EE14 5H560 AA02 BB04 BB07 BB17 DA13 EB01 GG04 JJ07 TT02 TT07 TT08 TT15 UA02 XA03

Claims (8)

[Claims] 1. A system for driving a compressor (4) by a brushless DC motor (3) controlled by an inverter (2), wherein a stator winding (3u) (3) of the brushless DC motor (3) is provided.
v) (3w) neutral point potential and stator winding (3u) (3
v) A resistor (5u) (5v) connected in parallel with (3w)
(5w) A brushless DC caused by a compressor failure is detected based on a difference potential from a neutral point potential and based on the detected difference potential.
A lock detecting method in a compressor driving device, wherein a lock of a motor (3) is detected. 2. The lock in the compressor drive device according to claim 1, wherein the lock of the brushless DC motor (3) caused by the compressor failure is detected based on the cycle of the detected difference potential. Detection method. 3. The brushless DC motor which is caused by a compressor failure in response to the frequency of the detected difference potential being a frequency other than three times the operating frequency of the brushless DC motor (3).
The lock detecting method for a compressor drive device according to claim 1, wherein it is detected that the lock of the C motor (3) has occurred. 4. A system for driving a compressor (4) by a brushless DC motor (3) controlled by an inverter (2), wherein a stator winding (3u) (3) of the brushless DC motor (3) is provided.
v) (3w) neutral point potential and stator winding (3u) (3
v) A resistor (5u) (5v) connected in parallel with (3w)
(5w) a difference potential detection means (6) for detecting a difference potential from a neutral point potential, and a brushless DC caused by a compressor failure based on the difference potential detected by the difference potential detection means (6).
A lock detecting device for a compressor driving device, comprising: lock determining means (8), (14), and (24) for determining whether or not the motor (3) is locked. 5. The lock determination means (24) determines whether or not lock of the brushless DC motor (3) due to a compressor failure has occurred based on the cycle of the detected difference potential. A lock detecting device in the compressor drive device according to claim 4. 6. The lock determination means (14) determines whether the frequency of the detected difference potential is a frequency other than three times the operating frequency of the brushless DC motor, and the frequency is a frequency other than three times. 5. The lock detecting device according to claim 4, wherein the lock detecting device determines that the brushless DC motor is locked due to a compressor failure. 7. The lock determination means (24) determines whether or not lock of the brushless DC motor (3) due to a compressor failure has occurred based on the amplitude of the detected difference potential. A lock detecting device in the compressor drive device according to claim 4. 8. The brushless DC motor (3) has a rotor (3e) provided with a permanent magnet (3f) embedded therein. 7. A lock detecting device in the compressor drive device according to item 5.