JP5194815B2 - Smoothing capacitor abnormality detection circuit and electronic device provided with the same - Google Patents

Description

  The present invention relates to an electronic device that is supplied with a DC voltage including a pulsating current as a power supply voltage, and more particularly to an abnormality detecting circuit for a smoothing capacitor that detects an abnormality of a smoothing capacitor that smoothes the pulsating current of the DC voltage.

  Conventionally, there is an outdoor unit of an air conditioner, for example, as an electronic device provided with a circuit for detecting deterioration or abnormality of a smoothing capacitor. A compressor is mounted on the outdoor unit of the air conditioner, and a motor in the compressor is controlled by an inverter. The DC power supply of this inverter is used by rectifying a commercial power supply, and an electrolytic capacitor is used for smoothing the rectified voltage.

  Generally, the capacity of the electrolytic capacitor for smoothing decreases with time. For this reason, the ripple voltage contained in the rectified DC voltage increases. This increase in ripple voltage is harmful to inverter control, and the life of the electrolytic capacitor is defined as the time when the ripple voltage reaches a predetermined voltage. This life detection method will be described with reference to FIGS. 1 to 4 and FIG.

  FIG. 1 is a main block diagram showing a power converter of an air conditioner outdoor unit equipped with a conventional capacitor deterioration detection circuit, and FIG. 2 is a graph showing a DC voltage and a load current of a smoothing capacitor. Indicates when the smoothing capacitor is not deteriorated, and (B) indicates when the smoothing capacitor is deteriorated. FIG. 3 is a table showing the contents of the characteristic table, and FIG. 4 is a graph of each characteristic line corresponding to the reference ripple voltage, the warning ripple voltage, and the abnormal ripple voltage. FIG. 8 is an operation flowchart for explaining the conventional control. 1 to 4 also include a part related to the present invention, but the part described here is the same as the conventional example, and is used for the description of the background art.

  FIG. 1 is a principal block diagram showing a power conversion device for an air conditioner outdoor unit. A motor drive circuit using an inverter used in a compressor (not shown), a power supply to the motor drive circuit, and a capacitor The power supply circuit provided with the deterioration detection circuit is shown.

  This power supply circuit includes a rectifying unit 2 composed of four rectifying diodes connected to an AC power source 1, a smoothing capacitor 3, a DC voltage detecting unit 4 for detecting a ripple voltage of the smoothing capacitor 3, and an entire motor driving circuit. And a load current detection unit 5 for detecting the load current of the current.

  On the other hand, the motor drive circuit includes a conversion unit 6 in which three sets of arms configured by connecting two switching elements connected in parallel to each other in series, a motor drive unit 8 for driving the conversion unit 6, The controller 9 includes a microcomputer that outputs a drive signal to the motor driver 8. The control unit 9 includes a storage unit 9a inside. And the connection point of the switching element of each arm of the conversion part 6 is connected to each winding of the three-phase motor 7 corresponding to each.

  The DC voltage detection unit 4 is configured such that both ends of two resistors connected in series are connected in parallel to the smoothing capacitor 3, and the DC voltage of the smoothing capacitor 3 is divided into a predetermined voltage. The output voltage is output to the A / D conversion terminal 9b of the control unit 9. In the control unit 9, the analog voltage divided and input to the A / D conversion terminal 9b is digitally converted every 1 mS within a predetermined sampling period, for example, 100 mS (millisecond), and the converted digital voltage is converted into a smoothing capacitor. Is stored in the storage unit 9a.

  The load current detection unit 5 connects a resistor in series between the conversion unit 6 and the rectification unit 2 in order to measure the load current flowing back from the three-phase motor 7, and the voltage at both ends of this resistor is connected to the control unit 9. The data is output to the A / D conversion terminal 9c. The control unit 9 simultaneously converts the analog voltage (corresponding to the load current) inputted to the A / D conversion terminal 9c at the same time as the measurement timing of the divided DC voltage, and the converted digital voltage indicates the load current. It is stored as a value in the storage unit 9a.

  Generally, when a constant AC voltage is rectified and applied to a smoothing capacitor, and a constant load is applied to the smoothing capacitor, a decrease in the capacity of the smoothing capacitor appears as an increase in ripple voltage. That is, when the capacity is large, the ripple voltage is small, and when the capacity is small, the ripple voltage is large. On the other hand, when the capacity of the smoothing capacitor is the same, the ripple voltage increases as the load is heavier, that is, as the load current increases.

  This state is shown in the graph of FIG. 2A shows the relationship between the DC voltage across the smoothing capacitor when the smoothing capacitor is not deteriorated, that is, when the capacity is large, and the load current at that time, and FIG. The relationship between the DC voltage across the smoothing capacitor when the capacitance is small and the load current at that time is shown.

  In FIG. 2, the voltage between the maximum value and the minimum value of the DC voltage is referred to as Vr: ripple voltage. In order to detect the maximum value and the minimum value of the DC voltage, the control unit 9 pairs the DC voltage and the load current at the same time during the sampling period, that is, the measurement time: Tm = 100 mS. The measurement was performed 100 times and stored in the storage unit 9a.

  When the 100 mS sampling period (measurement time) has elapsed, the waveform of FIG. 2 is stored in the storage unit 9a as 100 sets of data of the DC voltage value and the load current value. And the control part 9 searches the maximum value and minimum value of the stored DC voltage, and calculates | requires the voltage difference between these, ie, ripple voltage: Vr. At the same time, the load current value corresponding to the maximum value and the minimum value is obtained, and the average load current is calculated.

  Then, the control unit 9 determines the deterioration state of the smoothing capacitor 3 by comparing the calculated average load current and the obtained ripple voltage with a characteristic table in which a comparison ripple voltage value that is a predetermined value is stored. . This characteristic table is stored in advance in the storage unit 9a as the table shown in FIG.

  FIG. 3 is a table showing the contents of the characteristic table. The items in the vertical direction of the table are the load current (unit: amperes) and comparative ripple voltage (unit: volts) from the left. The comparative ripple voltage is further divided into the reference ripple voltage, warning ripple voltage, and abnormal ripple voltage. It is divided into. The load current is divided into 1 to 14 amperes in the vertical direction, and the respective values of the comparison ripple voltages are defined correspondingly.

  The reference ripple voltage represents the characteristics of the undegraded smoothing capacitor 3, and if the warning ripple voltage is higher than this, the equipment will not fail immediately, but in some cases, there is a possibility of failure. If the ripple voltage is higher than this, the abnormal ripple voltage indicates that the rated operation of the device cannot be performed, that is, the ripple voltage has a possibility of failure.

  The warning ripple voltage and the abnormal ripple voltage may be determined according to the characteristics of the device, but in this example, they are defined as shown in FIG. In this example, a ripple voltage of 16.5 V or more is defined as a ripple limit voltage, and the device is stopped when the ripple voltage is exceeded.

  FIG. 4 is a graph of characteristics corresponding to the reference ripple voltage, warning ripple voltage, and abnormal ripple voltage when the ripple voltage is on the vertical axis and the load current is on the horizontal axis.

  The reference characteristic line has a ripple voltage of 14.6V even when the rated maximum load current is 14A, and has a margin of 1.9V with respect to the ripple limit voltage of 16.5V. The warning characteristic line has a ripple voltage of 16.5 V when the rated maximum load current is 14 A, which is the same as the ripple limit voltage. Therefore, the limit line of the possibility that the maximum capacity operation by the rating cannot be performed when the ripple voltage further increases is shown.

  The abnormal characteristic line shows a limit line that reaches the ripple limit voltage of 16.5V when the load current is 10A, and the ripple limit voltage is exceeded when operating above this rated minimum load current. This means that maximum capacity operation is no longer possible within the rated voltage.

  Next, the operation of the control unit 9 will be described using the flowchart of FIG. FIG. 8 shows a process of monitoring the ripple voltage, and the same process is always executed when the device is installed and normally operating. In FIG. 8, ST represents a step, and the number following this indicates a step number. Y represents Yes and N represents No.

  In the process of monitoring the ripple voltage in FIG. 8, the control unit 9 sets an initial value 0 to the counter as the number of measurements for calculating the ripple voltage (ST90). Next, 1 is added to the counter (ST91), and the DC voltage is measured by the DC voltage detector 4 and stored in the storage unit 9a (ST92). Next, the load current detection unit 5 measures the load current and stores it in the storage unit 9c (ST93).

  Then, it is confirmed whether 100 measurements have been completed, that is, whether a sampling period of 100 mS has elapsed (ST94). Note that the processing from ST91 to ST94 is performed at 1 mS. If 100 measurements have not been completed (ST94-N), jump to ST91 and continue the measurement. When 100 measurements are completed (ST94-Y), the 100 maximum voltages and minimum voltages stored in the storage unit 9c are searched, and the ripple voltage is calculated by subtracting the minimum voltage from the maximum voltage. (ST95).

  Next, the load current corresponding to the maximum voltage and the minimum voltage stored in the storage unit 9c is taken out, and the average value is calculated (ST96). Then, by searching the characteristic table, the alarm ripple voltage corresponding to the load current having the value closest to the average value of the load current is extracted and compared with the ripple voltage calculated in ST95 (ST97).

  If the ripple voltage is less than or equal to the value of the warning characteristic line, that is, if the measured ripple voltage is less than or equal to the warning ripple voltage (ST97-Y), the smoothing capacitor 3 is normal, so jump to ST90 and continue monitoring. To do.

  On the other hand, when the measured ripple voltage is equal to or higher than the warning ripple voltage (ST97-N), the characteristic table is searched to extract the abnormal ripple voltage corresponding to the load current having the value closest to the average value of the load current and calculated in ST5. Compare with the ripple voltage (ST98). When the ripple voltage is less than or equal to the value of the abnormal characteristic line, that is, when the measured ripple voltage is less than or equal to the abnormal ripple voltage (ST98-Y), the warning operation range shown in FIG. A warning message is displayed (ST99). And it jumps to ST90 and continues monitoring.

  On the other hand, if the ripple voltage is not less than or equal to the value of the abnormal characteristic line, that is, if the measured ripple voltage exceeds the abnormal ripple voltage (ST98-N), the operation of the device is stopped because the failure range is shown in FIG. ST100), for example, a failure message is displayed on a display unit (not shown) (ST101), and the control is terminated. In this way, the ripple voltage is determined in correspondence with the load current, and the warning or the operation is stopped (see, for example, Patent Document 1).

  However, in some cases, the lifetime of the electrolytic capacitor cannot be reliably determined only by such a method. For example, a smoothing capacitor has a high withstand voltage and a relatively large capacity, and therefore the size increases. For this reason, a plurality of small electrolytic capacitors are often connected in parallel.

  At this time, one capacitor may have a lifetime earlier than the other capacitors, and the capacitor explosion valve may open. When the bomb valve opens, a small explosion occurs that opens the valve.As a result of this small explosion, the capacitor case is distorted, the electrolyte sprays out, and the internal insulation sheet is deformed. Or

  If the capacitor case is only distorted or the electrolyte solution is ejected, it will only cause a decrease in capacitance, and it can be detected if only the ripple voltage is monitored as in the prior art. If the internal insulating sheet is deformed and the two electrodes come into contact with each other, it is short-circuited. Therefore, it can be recognized that the fuse or the breaker of the commercial power source is cut and a failure occurs.

A problem arises when the internal insulating sheet is deformed to deteriorate the insulation performance between the two electrodes, and a small amount of current flows between the electrodes in the vicinity of the applied voltage. In such a case, the peak voltage is clipped and the ripple voltage is apparently reduced. For this reason, the method of monitoring only the ripple voltage has a problem that it is impossible to detect the life of the electrolytic capacitor that has caused such a halfway failure.
JP2007-240450 (page 6-8, FIG. 4)

  The present invention solves the above-described problems, and provides an abnormality detecting means for a smoothing capacitor that can be used in various electronic devices, can detect the life easily, reliably and can be configured at low cost. With the goal.

In order to solve the above-described problem, the present invention measures a load current detection unit that measures a load current of a load connected to a smoothing capacitor to which a DC voltage including a pulsating current is applied, and measures a DC voltage across the smoothing capacitor. Corresponding to a DC voltage detection unit, a control unit to which the DC voltage detection unit and the load current detection unit are connected , a comparison ripple voltage value that is a predetermined ripple voltage value corresponding to the load current, and the load current and a storage unit for storing and comparing the average voltage value is a predetermined average voltage values,
The control unit calculates a ripple voltage value and an average voltage value from a DC voltage applied to the smoothing capacitor, compares the ripple voltage value with the comparison ripple voltage value, and the ripple voltage value is a predetermined value. if: by comparing the comparison average voltage value corresponding to the value of the load current measured by the load current detection unit and the average voltage value to detect an abnormality of the smoothing capacitor.

  The comparison average voltage value includes a reference average voltage value indicating an initial characteristic of the smoothing capacitor, a warning average voltage value indicating that the smoothing capacitor is in a state requiring attention, and the smoothing capacitor is determined to have failed. And an abnormal average voltage value indicating that it is in a state.

  The reference average voltage value is stored in the storage unit, and the warning average voltage value and the abnormal average voltage value are calculated from the reference average voltage value based on a predetermined condition.

  Further, the control unit continuously changes the magnitude of the load, measures the load current corresponding to the change in the load and the DC voltage applied to the smoothing capacitor, and measures the DC An average voltage value is calculated from the voltage value, and the average voltage value is stored in the storage unit as the reference average voltage value corresponding to the measured load current value.

  On the other hand, a smoothing capacitor abnormality detection circuit comprising any of the means described above is mounted on an electronic device.

By using the above means, according to the abnormality detection circuit for a capacitor according to the present invention,
In the invention according to claim 1, in order to determine the abnormality of the smoothing capacitor by comparing the measured average voltage value with a predetermined comparison average voltage value corresponding to the load current, the explosion valve is ruptured. An abnormality such as a smoothing capacitor whose insulation performance has deteriorated can be accurately determined, and an abnormality of the smoothing capacitor can be warned before the device is damaged. In general, a capacitor abnormality detection circuit can be configured at low cost and simply by adding a load current detection unit and a DC voltage detection unit to a control unit that controls the device.

  In the invention according to claim 2, the comparison average voltage value is a reference average voltage value indicating an initial characteristic of the smoothing capacitor, a warning average voltage value for warning an abnormality of the smoothing capacitor, and an abnormal average voltage for judging the smoothing capacitor as a failure. Because it is composed of values, the smoothing capacitor can be classified into three states: normal, warning, and abnormal. Appropriate processing is performed according to each state, and an appropriate message is notified to the user. be able to.

  In the invention according to claim 3, since the warning average voltage value and the abnormal average voltage value are calculated from the reference average voltage value, if the reference average voltage value can be determined, the warning average voltage value and the abnormal average voltage value are determined. Can be easily determined. Moreover, the capacity | capacitance of a memory | storage part can be reduced by calculating these at the time of the actual measurement and comparison of an average voltage.

  In the invention according to claim 4, in order to calculate the comparison average voltage value of the capacitor deterioration detection circuit for each device in advance, compared to the case where the comparison average voltage value is uniformly defined using the design value, Thus, it is possible to detect the abnormality of the capacitor accurately.

The invention according to claim 5 is applicable to various failure conditions of the electrolytic capacitor by applying the abnormality detection circuit of the smoothing capacitor to a power conversion device mounted on an electronic device such as an outdoor unit of an air conditioner. It is possible to accurately detect the abnormality of the electrolytic capacitor, and to limit the operation of the air conditioner according to the degree of abnormality. You can drive.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the attached drawings. In addition, the same number is given about the structure demonstrated by background art, and detailed description is abbreviate | omitted.

  FIG. 1 is a principal block diagram showing a power conversion device for an air conditioner outdoor unit described in the background art. The circuit itself is the same as the background art, but the function (processing contents) of the control unit 9 is different. Hereinafter, the difference from the background art will be mainly described.

  In FIG. 1, the DC voltage detection unit 4 divides the DC voltage of the smoothing capacitor 3 into a predetermined voltage, and outputs the divided voltage to the A / D conversion terminal 9 b of the control unit 9. In the control unit 9, the analog voltage divided and input to the A / D conversion terminal 9b is digitally converted every 1 mS within a predetermined sampling period, for example, 100 mS (millisecond), and the converted digital voltage is converted into a smoothing capacitor. Is stored in the storage unit 9a.

  In order to measure the load current flowing back from the three-phase motor 7, the load current detection unit 5 connects a resistor in series between the conversion unit 6 and the rectification unit 2, for example, and controls the voltage across the resistor to the control unit 9. To the A / D conversion terminal 9c. The control unit 9 converts the analog voltage (corresponding to the load current) inputted to the A / D conversion terminal 9c almost simultaneously with the measurement timing of the divided DC voltage, and converts the converted digital voltage to the load current. It is stored in the storage unit 9a as the indicated value.

  The smoothing capacitor abnormality detection circuit includes a DC voltage detection unit 4, a load current detection unit 5, and a control unit 9. In this embodiment, the sampling period is set to 100 mS in order to distinguish from the commercial power supply instantaneous interruption time. This is because the momentary interruption time of the commercial power supply is a temporary voltage drop of about several tens of milliseconds, and the ripple voltage increase due to the drop of the DC voltage is also temporary. On the other hand, the deterioration of the smoothing capacitor appears as a constant increase in the ripple voltage over the instantaneous interruption time.

  When there is no restriction due to such an instantaneous interruption time, the commercial power supply cycle, for example, 20 mS, which is one cycle at 50 Hz, may be used.

  By the way, the life of a smoothing capacitor generally refers to the case where the capacity of the capacitor is gradually decreased with the passage of time and is reduced to a predetermined ratio from the initial capacity. However, since the predetermined ratio varies depending on the voltage and load applied to the capacitor, it is determined in consideration of the maximum load when designing a device using the capacitor.

  In addition, when a constant AC voltage is rectified and applied to a smoothing capacitor, and a constant load is applied to the smoothing capacitor, a decrease in the capacity of the smoothing capacitor appears as an increase in ripple voltage. That is, when the capacity is large, the ripple voltage is small, and when the capacity is small, the ripple voltage is large. On the other hand, when the capacity of the smoothing capacitor is the same, the ripple voltage increases as the load is heavier, that is, as the load current increases. When the explosion valve of the electrolytic capacitor is ruptured, the two electrodes of the electrolytic capacitor are short-circuited, the capacity is reduced, and the insulation performance between the two electrodes is reduced.

  This state is shown in the graph of FIG. FIG. 2A shows the relationship between the DC voltage across the smoothing capacitor when the smoothing capacitor is undegraded, that is, when the capacity is large, the load current at that time, and the average voltage. FIG. Normal deterioration, that is, the DC voltage across the smoothing capacitor when the capacity is reduced, and the DC voltage across the smoothing capacitor when the smoothing capacitor explosion valve bursts and the insulation performance between the two electrodes is reduced. The relationship between the load current and each average voltage at that time is shown.

  In FIG. 2A, Vr indicates the ripple voltage of the smoothing capacitor, and Va indicates the average voltage of the smoothing capacitor.

  On the other hand, in FIG. 2B, Vr1 indicates a ripple voltage when the smoothing capacitor is normal deterioration, and Vr2 indicates a ripple voltage when the smoothing capacitor is deteriorated due to valve rupture. Further, Va1 indicates an average voltage when the smoothing capacitor is in a normal deterioration, and Va2 indicates an average voltage in an abnormal state due to the valve burst of the smoothing capacitor.

  When the insulation performance deteriorates due to the deterioration of the smoothing capacitor due to the valve rupture, the specified voltage or more may be clipped by a short circuit, and the average voltage Va2 is lower than the average voltage Va1 compared to the smoothing capacitor where the valve is not ruptured. To do. In this case, since the voltage of Vr2 is lower than Vr1, there may be a case where an abnormality due to the bursting of the smoothing capacitor valve cannot be found even if only the ripple voltage is viewed.

  In the present invention, the life of the smoothing capacitor is accurately detected by monitoring the average voltage together with the ripple voltage.

  In order to detect the maximum value and the minimum value of the DC voltage, which is the original data for calculating the ripple voltage, the control unit 9 detects the DC voltage and the load current at that time during the sampling period, that is, the measurement time: Tm = 100 mS. Are measured in pairs at the required number of times, for example, 100 times, and stored in the storage unit 9a.

  When the 100 mS sampling period (measurement time) has elapsed, the waveform of FIG. 2 is stored in the storage unit 9a as 100 sets of data of the DC voltage value and the load current value. And the control part 9 searches the maximum value and minimum value of the stored DC voltage, and calculates | requires the voltage difference between these, ie, ripple voltage: Vr. At the same time, the load current value corresponding to the maximum value and the minimum value is obtained, and the average load current is calculated. Further, the average voltage Va of the 100 stored DC voltage values is calculated.

  And the control part 9 was comprised by the comparison ripple voltage value which is a predetermined value, and the comparison average voltage value for the calculated average load current, the calculated ripple voltage, and the calculated average voltage. The deterioration state of the smoothing capacitor 3 is determined by comparison with the characteristic table. This characteristic table is stored in advance in the storage unit 9a as the table shown in FIG.

  FIG. 3 is a table showing the contents of the characteristic table. The items in the vertical direction of the table are the load current (unit: amperes), comparative ripple voltage (unit: volts), and comparative average voltage (unit: volts) from the left. The warning ripple voltage and the abnormal ripple voltage are classified into the reference average voltage, the warning average voltage, and the abnormal average voltage. The load current is divided into 1 to 14 amperes in the vertical direction, and the values of the comparison ripple voltage and the comparison average voltage are defined correspondingly.

  The reference ripple voltage and the reference average voltage represent the characteristics of the undegraded smoothing capacitor 3, and if the warning ripple voltage is a ripple voltage higher than this, the device will not immediately fail, but in some cases it may cause a failure. This indicates that there is a ripple voltage that may be. Similarly, the warning average voltage indicates that if the average voltage is less than or equal to this, the device does not fail immediately, but it may cause a failure in some cases.

  In addition, when the ripple voltage is higher than this, the abnormal ripple voltage indicates that the rated operation of the device cannot be performed, that is, the ripple voltage has a possibility of failure. Similarly, the abnormal average voltage indicates that there is a possibility of failure when the average voltage is lower than this.

  The warning ripple voltage and abnormal ripple voltage, and the warning average voltage and abnormal average voltage may be determined according to the characteristics of the device. In this embodiment, the values related to the comparison ripple voltage are defined as shown in FIG. Yes. In this embodiment, a ripple voltage of 16.5 V or more is defined as a ripple limit voltage, and the device is stopped when the ripple voltage is exceeded. On the other hand, the value of the comparative average voltage relationship is defined as shown in FIG. In this embodiment, a voltage equal to or lower than the abnormal average voltage is defined as a limit voltage, and the apparatus is stopped when the voltage is lower than this.

  FIG. 4 is a graph of characteristics corresponding to the reference ripple voltage, warning ripple voltage, and abnormal ripple voltage when the ripple voltage is on the vertical axis and the load current is on the horizontal axis. Here, the rated maximum load current is a load current when operating at a maximum capacity when the operating voltage range of the target electronic device, for example, an air conditioner is AC207 to 253V (rated 230V) and used at a voltage of 207V. Is shown. On the other hand, the rated minimum load current is a load current that is used at a voltage of 253 V and is operated at the maximum capacity. In general, an inverter-controlled air conditioner has a characteristic that, when operated with the same capacity, the load current increases when the input voltage is low, and the load current decreases when the input voltage is high.

  The reference characteristic line has a ripple voltage of 14.6V even when the rated maximum load current is 14A, and has a margin of 1.9V with respect to the ripple limit voltage of 16.5V. The warning characteristic line has a ripple voltage of 16.5 V when the rated maximum load current is 14 A, which is the same as the ripple limit voltage. Therefore, it shows a limit line in which the maximum capacity operation cannot be performed within the input voltage range specified in the specification when the ripple voltage further increases.

  The abnormal characteristic line shows a limit line that reaches the ripple limit voltage of 16.5V when the load current is 10A, and the ripple limit voltage is exceeded when operating above this rated minimum load current. This means that the maximum capacity operation can no longer be performed within the specified input voltage. In general, the case where the rated operation cannot be performed is regarded as a failure, but the continuous operation can be performed if the operation is less than the maximum capacity operation. Therefore, it is to be determined by the specifications of the device whether it is determined that the failure is greater than the abnormal characteristic line and less than or equal to the ripple limit voltage, or is within the warning operation range. In this embodiment, the failure range is used.

  FIG. 5 shows the average voltage (V) on the vertical axis and the load current (A) on the horizontal axis, which corresponds to the reference average voltage, warning average voltage, and abnormal average voltage in the comparison average voltage of FIG. 5 is a graph showing characteristics of a reference characteristic line, a warning characteristic line, and an abnormal characteristic line.

  The reference characteristic line has an average voltage of 250 V even when the rated maximum load current is 14 A, and has a margin of 30 V with respect to the warning comparison voltage. Similarly, the warning characteristic line has an average voltage of 220V and has a margin of 20V with respect to the abnormal characteristic line. In this way, normal cases, warnings, and abnormal cases are divided by ranges. Therefore, within these ranges, even if there are temporary voltage fluctuations, such as fluctuations in commercial power supply voltage or temporary load fluctuations due to solenoid on / off control, etc., errors in normality, warning, and abnormality will occur. There are few judgments. Further, the ripple voltage and the average voltage are constantly monitored, and even if an erroneous determination is made, the correct determination result is restored as soon as there is no cause.

  Each characteristic line in the comparative average voltage has the same meaning as each characteristic line in the comparative ripple voltage. If the average voltage is equal to or higher than the warning characteristic line, it indicates that the smoothing capacitor 3 is normal and abnormal from the warning characteristic line. The average voltage value between the characteristic lines indicates that the smoothing capacitor 3 is rapidly deteriorating due to valve rupture or heat generation of the smoothing capacitor 3, and the average voltage below the abnormal characteristic line is the life of the smoothing capacitor 3 In the worst case, if the device is used as it is, the case where the device may ignite is shown.

  Each reference characteristic line in the comparative ripple voltage and the comparative average voltage may be created using standard capacitor characteristics as a design value, but the margin may be reduced due to initial variations in capacitor capacitance. Accordingly, in the present embodiment, the ripple voltage and the average voltage are calculated by measuring the DC voltage of the mounted smoothing capacitor 3 while changing the load current, that is, the operation capacity of the air conditioner, in the product test at the time of manufacturing the air conditioner. The data of the reference ripple voltage and the reference average voltage in the table 3 is rewritten.

  As a result, highly accurate control corresponding to the characteristics of the individual capacitors becomes possible. In this case, the warning ripple voltage and the abnormal ripple voltage are obtained by multiplying the reference ripple voltage data by a predetermined coefficient or adding a predetermined value. Similarly, the warning average voltage and the abnormal average voltage are obtained by multiplying the data of the reference average voltage by a predetermined coefficient or adding a predetermined value. Further, as described above, since the comparison value is calculated for each smoothing capacitor attached to each device, an accurate comparison voltage value corresponding to the characteristics of the smoothing capacitor can be defined.

  In the characteristic table of FIG. 3, the load current is defined in increments of 1A, but is not limited to this and may be defined more finely. Further, the comparison ripple voltage may be supplemented by calculating the load current value and each ripple voltage value based on the difference between adjacent load current values and the corresponding difference between adjacent ripple voltage values. . Note that the load current value and each average voltage value may be calculated and complemented by the difference between adjacent average voltages in the same manner as for the comparative average voltage.

  Further, the warning ripple voltage and the abnormal ripple voltage or the warning average voltage and the abnormal average voltage may be stored in advance in the storage unit 9a as a characteristic table, or when the characteristics of the smoothing capacitor 3 are inspected, the reference ripple You may calculate and use each time from a voltage value or a reference average voltage value.

  In this embodiment, the reference ripple voltage and the reference average voltage are measured in the product test at the time of manufacturing the air conditioner in which the smoothing capacitor 3 is in the initial state. However, the present invention is not limited to this. For example, the measurement may be performed again every year or every predetermined operation time. However, in this case, the smoothing capacitor 3 has a measured reference ripple voltage value that is larger than the initial state and a reference average voltage value that is lower than the initial state due to secular change. The calculation of the ripple voltage and the calculation of the warning average voltage and the abnormal average voltage are obtained by multiplying a coefficient corresponding to the secular change different from the initial state or adding a predetermined value.

  Next, the operation of the control unit 9 will be described using the flowchart of FIG. FIG. 6A shows a process of monitoring the ripple voltage and the average voltage, and the same process is always executed when the device is installed and normally operating. On the other hand, FIG. 6B shows measurement processing of the ripple reference characteristic and the reference average voltage characteristic, and is configured as a part of an equipment inspection program executed at a factory production line or equipment repair site. .

  In FIG. 6, ST represents a step, and the subsequent number indicates a step number. Y represents Yes and N represents No.

  First, in the process of monitoring each voltage in FIG. 6A, the control unit 9 sets an initial value 0 to the counter as the number of measurements for calculating the ripple voltage and the average voltage (ST0). Next, 1 is added to the counter (ST1), the DC voltage detector 4 measures the DC voltage, and stores it in the storage unit 9a (ST2). Next, the load current detection unit 5 measures the load current and stores it in the storage unit 9c (ST3).

  Then, it is confirmed whether 100 measurements have been completed, that is, whether a sampling period of 100 mS has elapsed (ST4). Note that the processing from ST1 to ST4 is performed at 1 mS. If 100 measurements have not been completed (ST4-N), jump to ST1 and continue the measurement. When the measurement of 100 times is completed (ST4-Y), the maximum voltage and the minimum voltage are searched from 100 data stored in the storage unit 9c, and the minimum voltage is subtracted from the maximum voltage. A ripple voltage is calculated (ST5).

  Next, the load current corresponding to the voltage value of the maximum voltage and the minimum voltage stored in the storage unit 9c is taken out, and the average value is calculated (ST6). Next, the average voltage of the 100 stored voltage values is calculated (ST7). Then, by searching the characteristic table, the alarm ripple voltage corresponding to the load current having the value closest to the average value of the load current is extracted and compared with the ripple voltage calculated in ST5 (ST8).

  When the ripple voltage is less than or equal to the value of the warning characteristic line, that is, when the measured ripple voltage is less than or equal to the warning ripple voltage (ST8-Y), the load closest to the average value of the load current is searched by searching the characteristic table. The warning average voltage corresponding to the current is taken out and compared with the average voltage calculated in ST7 (ST9).

  If the average voltage is greater than or equal to the value of the warning characteristic line, that is, if the measured average voltage is greater than or equal to the warning average voltage (ST9-Y), the smoothing capacitor 3 is normal and jumps to ST0 and continues monitoring. When the measured average voltage is lower than the warning average voltage (ST9-N) and when the measured ripple voltage is higher than the warning ripple voltage (ST8-N), the characteristic table is searched and the average value of the load current is the highest. An abnormal ripple voltage corresponding to a load current having a close value is taken out and compared with the ripple voltage calculated in ST5 (ST10).

  When the ripple voltage is equal to or higher than the value of the abnormal characteristic line, that is, when the measured ripple voltage is equal to or higher than the abnormal ripple voltage (ST10-N), the operation of the device is stopped because the failure range is shown in FIG. ST13) For example, a failure message is displayed on a display unit (not shown) (ST14), and the control is terminated.

  On the other hand, if the ripple voltage is less than or equal to the value of the abnormal characteristic line, that is, if the measured ripple voltage is less than or equal to the abnormal ripple voltage (ST10-Y), it is confirmed whether the measured average voltage is greater than or equal to the abnormal average voltage (ST11). If the measured average voltage is equal to or lower than the abnormal average voltage (ST11-N), the process jumps to ST13 because the failure range is shown in FIG.

  And when the measured average voltage is more than an abnormal average voltage (ST11-Y), since it is the warning operation range shown in FIG.4 and FIG.5, a warning message is displayed on the display part which is not shown in figure (ST12), for example. And it jumps to ST0 and continues monitoring.

  Next, the ripple and average voltage reference characteristic measurement processing of FIG. 6B will be described. When the process is started, the control unit 9 first sets the counter to 1 as the value of the load current to be measured (ST20). This is because the value of the counter is associated with the value of the load current. For example, when the value of the counter is 1, the load current is 1 ampere.

  Next, for example, the air conditioner is operated in the heating operation mode, and the heating capacity is gradually increased from the stopped state. As a result, the load current of the device gradually increases (ST21).

  Then, the load current detector 5 measures the load current (ST22), and checks whether the load current is equal to the counter value (ST23). If the load current and the counter value are not equal (ST23-N), the process jumps to ST21.

  When the load current is equal to the counter value (ST23-Y), 1 is added to the counter (ST24). Then, the DC voltage is measured every 1 mS for 100 mS and stored in the storage unit 9a. The ripple voltage is calculated from the maximum voltage value and the minimum voltage value among the 100 stored voltage values, and this is counted as a counter. The value (load current) is stored in the table as the reference ripple voltage value in the characteristic table. Simultaneously, an average voltage of 100 voltage values is calculated, and this is stored in the table as a reference average voltage value of a characteristic table corresponding to the counter value (load current) (ST25).

  Next, it is confirmed whether the counter is 15 (ST26), that is, whether the end of the characteristic table is reached. If the counter is not 15 (ST26-N), the process jumps to ST21. If the counter is 15 (ST26-Y), the measurement is finished, so the reference characteristic line of the comparison ripple voltage in the table, that is, the warning characteristic line and the abnormal characteristic line based on the value of the reference ripple voltage, that is, Calculate the values of warning ripple voltage and abnormal ripple voltage and store them in the table. Also, based on the reference characteristic line of the comparison average voltage of the table, that is, the value of the reference average voltage, the warning characteristic line and the abnormal characteristic line, that is, the warning average voltage and the abnormal average voltage value are calculated and stored in the table. (ST27).

  As a result, 14 sets of comparison data corresponding to a load current of 1 to 14 amperes are stored in the table. In this embodiment, 14 sets of comparison data are converted into data in increments of 1 ampere. However, the number of sets of data conversion may be any value. In this case, the counter value is a value corresponding to the number of data sets.

  As described above, in order to determine the abnormality of the smoothing capacitor by comparing the measured average voltage value and the predetermined comparative average voltage value corresponding to the load current, the explosion valve bursts and the insulation performance Therefore, it is possible to accurately determine an abnormality such as a smoothing capacitor in which the resistance is lowered, and to warn of an abnormality of the smoothing capacitor before the device is damaged. In general, a capacitor abnormality detection circuit can be configured at low cost and simply by adding a load current detection unit and a DC voltage detection unit to a control unit that controls the device.

  In addition, both the configuration for monitoring the ripple voltage, which is the conventional technology, and the average voltage described in the present embodiment are monitored, and if any value falls outside the set range, a warning or failure is determined. Therefore, accurate determination can be made for various factors of smoothing capacitor deterioration.

  In addition, the comparison average voltage value is composed of a reference average voltage value indicating the initial characteristics of the smoothing capacitor, a warning average voltage value for warning an abnormality of the smoothing capacitor, and an abnormal average voltage value for determining the smoothing capacitor as a failure. Therefore, the state of the smoothing capacitor can be classified into three states: normal, warning, and abnormal. Appropriate processing can be performed according to each state, and an appropriate message can be notified to the user.

  Moreover, since the warning average voltage value and the abnormal average voltage value are calculated from the reference average voltage value, if the reference average voltage value can be determined, the warning average voltage value and the abnormal average voltage value can be easily determined. . Moreover, the capacity | capacitance of a memory | storage part can be reduced by calculating these at the time of the actual measurement and comparison of an average voltage.

  Furthermore, since the comparison average voltage value of the capacitor deterioration detection circuit is calculated in advance for each device, compared to the case where the comparison average voltage value is uniformly defined using the design value, a more accurate capacitor value can be obtained. Abnormal conditions can be detected.

  In addition, the comparison ripple voltage and the comparison average voltage corresponding to each reference characteristic line stored in the storage unit 9a at the time of manufacture are searched, and the ripple limit voltage has already been exceeded at the rated maximum load current or less than the comparison average voltage. In this case, since the corresponding capacitor can be determined as an initial defective product, an error may be displayed. In this way, the reliability of the product can be improved.

  Next, a method in which the smoothing capacitor abnormality determination by monitoring the average voltage is simplified will be described. The circuit configuration is the same as in FIG. 1, and only the processing contents of the control unit and the values stored in the storage unit are different. Therefore, the description will focus on the differences between the first embodiment and the second embodiment.

  In the second embodiment, regarding the smoothing capacitor abnormality determination by monitoring the average voltage, as described in the first embodiment, the determination is not made based on the value of the comparison average voltage corresponding to the load current, and is uniform regardless of the load current. It is determined using the value of the comparative average voltage determined in (1).

  For this reason, the number of data stored in the table is reduced as compared with the configuration of the first embodiment, and the processing is simplified. Accordingly, in the second embodiment, the data in the table of FIG. 3 is only the values of the load current and the comparison ripple voltage, and there is no data of the comparison average voltage. Instead, for example, a reference average voltage: 270 V, a warning average voltage: 250 V, an abnormal average voltage: 200 V, and values that are determined in advance uniformly regardless of the load current are used.

  Next, the operation of the control unit 9 will be described using the flowchart of FIG. FIG. 7 shows processing for monitoring the ripple voltage and the average voltage, and the same processing is always executed when the device is installed and normally operating.

  In FIG. 7, ST represents a step, and the subsequent number indicates a step number. Y represents Yes and N represents No.

  First, in the process of FIG. 7, the control unit 9 sets an initial value 0 to the counter as the number of measurements for calculating the ripple voltage and the average voltage (ST30). Next, 1 is added to the counter (ST31), the DC voltage is measured by the DC voltage detector 4, and stored in the storage unit 9a (ST32). Next, the load current detection unit 5 measures the load current and stores it in the storage unit 9c (ST33).

  Then, it is confirmed whether 100 measurements have been completed, that is, whether a sampling period of 100 mS has elapsed (ST34). The processes from ST31 to ST34 are performed at 1 mS. If 100 measurements have not been completed (ST34-N), the process jumps to ST31 and continues the measurement. When 100 measurements are completed (ST34-Y), the maximum voltage and the minimum voltage are searched from 100 data stored in the storage unit 9c, and the minimum voltage is subtracted from the maximum voltage. A ripple voltage is calculated (ST35).

  Next, the load currents corresponding to the voltage values of the maximum voltage and the minimum voltage stored in the storage unit 9c are extracted, and the average value is calculated (ST36). Next, the average voltage of the 100 stored voltage values is calculated (ST37). Then, by searching the characteristic table, the alarm ripple voltage corresponding to the load current having the value closest to the average value of the load current is extracted and compared with the ripple voltage calculated in ST35 (ST38).

  When the ripple voltage is equal to or lower than the value of the warning characteristic line, that is, when the measured ripple voltage is equal to or lower than the warning ripple voltage (ST38-Y), the predetermined warning average voltage: 250V and the average voltage calculated in ST37 Compare (ST39).

  If the average voltage is greater than or equal to the value of the warning characteristic line, that is, if the measured average voltage is greater than or equal to the warning average voltage (ST39-Y), the smoothing capacitor 3 is normal and jumps to ST30 to continue monitoring. When the measured average voltage is equal to or lower than the warning average voltage (ST39-N) and when the measured ripple voltage is equal to or higher than the warning ripple voltage (ST38-N), the rotational speed of the motor 7 that is the load is then decreased (ST40). ).

  Next, the characteristic table is searched to extract the abnormal ripple voltage corresponding to the load current having the value closest to the average value of the load current, and compared with the ripple voltage calculated in ST35 (ST41).

  If the ripple voltage is greater than or equal to the value of the abnormal characteristic line, that is, if the measured ripple voltage is greater than or equal to the abnormal ripple voltage (ST41-N), the operation of the device is stopped because of a failure (ST43), for example, not shown A failure message is displayed on the display unit (ST44), and the control is terminated.

  On the other hand, when the ripple voltage is less than or equal to the value of the abnormal characteristic line, that is, when the measured ripple voltage is less than or equal to the abnormal ripple voltage (ST41-Y), the failure is not a fatal failure but a warning level failure. A warning message is displayed on the display unit (ST42). And it jumps to ST30 and continues monitoring.

  In this case, a warning message is displayed and the number of rotations of the motor 7 remains lowered, so that the operation is performed with the load reduced. For this reason, it is possible to prolong the time when the fatal failure occurs, to secure as much time as possible until the user confirms the warning message and repairs, and to operate the device during this period.

  Further, since the average voltage is monitored in the same manner as in the first embodiment, it is possible to detect a failure in which an abnormality due to the bursting of the smoothing capacitor valve cannot be found only by looking at the ripple voltage of the smoothing capacitor.

  In the second embodiment, since the load current needs to be measured for determining the ripple voltage, the load current detection unit is provided. However, if only the average voltage is monitored, the load current detection unit may not be provided. .

  In the two embodiments described above, an example in which an abnormality detection circuit for a smoothing capacitor is provided in an outdoor unit of an air conditioner is described. However, the present invention is not limited to this, and a smoothing capacitor to which a DC voltage including a pulsating current is applied is described. It can be widely applied to electronic devices with large load fluctuations.

  In these two embodiments, the load current detection unit 5 is provided between the conversion unit 6 and the rectification unit 2. However, the present invention is not limited to this, and the consumption current (commercial power supply) of the device provided in the electronic device is not limited thereto. ) AC current measuring circuit may be used. For example, in an air conditioner or the like, a circuit for measuring AC current consumption is already provided in order to limit the current of the device, and the measured current value in this AC current consumption measuring circuit corresponds to the load current in this embodiment. Can be made.

  Thereby, since it is not necessary to provide the load current detection part 5 newly, cost reduction can be aimed at.

  In these two embodiments, the comparison average voltage value includes a reference average voltage value indicating an initial characteristic of the smoothing capacitor, a warning average voltage value for warning the abnormality of the smoothing capacitor, and an abnormal average voltage for determining the smoothing capacitor as a failure. However, the present invention is not limited to this, and it may be composed of a reference average voltage value and an abnormal average voltage value. It may be detected.

  High-voltage smoothing capacitors used in AC power supply circuits are generally expensive, and in conventional electronic equipment design, taking into account the decrease in capacitor capacity due to aging, an extra large margin is necessary with a margin. In some cases, a capacitor with a capacitance was used. Therefore, by providing the smoothing capacitor abnormality detection circuit of the above-described embodiment, it is only necessary to consider the decrease in the capacitance of the capacitor due to aging without giving this unnecessary margin. That is, since the smoothing capacitor to be used can be selected to have the minimum necessary capacity, the cost can be reduced.

It is a principal part block diagram which shows the power converter device of the air-conditioner outdoor unit provided with the degradation detection circuit of the capacitor | condenser by this invention. It is a graph which shows the direct-current voltage and load current of a smoothing capacitor, (A) shows the time when a smoothing capacitor is undegraded, and (B) shows the time when a smoothing capacitor is deteriorating, respectively. It is a table | surface which shows the content of the characteristic table. It is a graph of each characteristic line corresponding to a reference ripple voltage, a warning ripple voltage, and an abnormal ripple voltage. It is a graph of each characteristic line corresponding to a reference average voltage, a warning average voltage, and an abnormal average voltage. It is an operation | movement flowchart explaining the operation | movement of control in 1st Example. It is an operation | movement flowchart explaining the operation | movement of control in 2nd Example. It is a flowchart explaining the deterioration detection detection process of the conventional capacitor | condenser.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectification part 3 Smoothing capacitor 4 DC voltage detection part 5 Load current detection part 6 Conversion part 7 Three-phase motor 8 Motor drive part 9 Control part 9a Memory | storage part 9b, 9c A / D conversion terminal

Claims (5)

A load current detector for measuring a load current of a load connected to a smoothing capacitor to which a DC voltage including a pulsating current is applied; a DC voltage detector for measuring a DC voltage across the smoothing capacitor; and the DC voltage detector And a control unit to which the load current detection unit is connected , a comparison ripple voltage value that is a predetermined ripple voltage value corresponding to the load current, and a comparison average voltage that is a predetermined average voltage value corresponding to the load current and a storage unit for storing a value,
The control unit calculates a ripple voltage value and an average voltage value from a DC voltage applied to the smoothing capacitor, compares the ripple voltage value with the comparison ripple voltage value, and the ripple voltage value is a predetermined value. if: by comparing the comparison average voltage value corresponding to the value of the load current measured by the load current detection unit and the average voltage value, characterized in that to detect an abnormality of the smoothing capacitor An abnormality detection circuit for a smoothing capacitor.   The comparison average voltage value includes a reference average voltage value indicating an initial characteristic of the smoothing capacitor, a warning average voltage value indicating that the smoothing capacitor is in a state requiring attention, and a state in which the smoothing capacitor is determined to be faulty. The abnormality detection circuit for a smoothing capacitor according to claim 1, comprising an abnormal average voltage value indicating that   3. The reference average voltage value is stored in the storage unit, and the warning average voltage value and the abnormal average voltage value are calculated from the reference average voltage value based on a predetermined condition. The smoothing capacitor abnormality detection circuit described.   The control unit continuously changes the size of the load, measures the load current corresponding to the change in the load and the DC voltage applied to the smoothing capacitor, 4. The smoothing capacitor according to claim 3, wherein an average voltage value is calculated from the value, and the average voltage value is stored in the storage unit as the reference average voltage value corresponding to the measured load current value. Anomaly detection circuit. Electronic apparatus having an abnormality detection circuit of the smoothing capacitor according to any one of claims 1 to 4.

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