JPH11356036A - Direct-current power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct-current power supply which makes it possible to detect timing of replacement of a smoothing capacitor due to its life and predict the life of a smoothing capacitor. SOLUTION: A life detection circuit 35 calculates voltage application time for a capacitor 19 based on a direct-current voltage detected through a voltage detection circuit 28, and is fed with an ambient temperature from a temperature detection circuit 29 and a ripple current value from a ripple current detection circuit 30 every hour of the voltage applying time. An predicted life time coefficient corresponding to the ambient temperature and the ripple current value is obtained from life characteristic data stored in a parameter setting circuit 34, and the reciprocal thereof is added to a passed life time. If the passed life time exceeds an expected life time, an alarm is outputted. A life prediction circuit 36 predicts a predicted life time based on the present ambient temperature, ripple current value, life characteristic data, expected life time and passed life time at the replacement of, or during operation of, the capacitor 19, and displays it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply for supplying a DC voltage obtained by rectifying an AC power output by a rectifier circuit and smoothing the output by a capacitor to a load.

[0002]

FIG. 5 shows a configuration of an inverter device using this type of DC power supply device. In FIG. 5, the inverter device 1 includes a DC power supply device 2 and an inverter circuit 3, and the DC power supply device 2 includes an AC reactor 4, a rectifier circuit 5, a DC reactor 6, and a smoothing capacitor 7. Have been.
The inverter circuit 3 is configured by connecting switching elements in a three-phase bridge, and the rectifier circuit 5 is configured by connecting rectifier diodes in a three-phase bridge. The input of the inverter device 1 is connected to a commercial three-phase AC power supply 8, and the output is connected to a winding terminal of an induction motor 9. The inverter circuit 3 performs a switching operation according to a commutation signal given to each switching element from an inverter control circuit (not shown), and outputs a variable voltage and a variable frequency AC voltage, thereby driving the induction motor 9 at a variable speed. It has become.

The waveform of the input current flowing from the AC power supply 8 into the inverter device 1 is represented by the power supply impedance, that is, the system impedance of the AC power supply 8 and the AC reactor 4.
Greatly changes according to the combined impedance with the reactance of the above and the input current value. FIG. 6A shows an input current waveform when there is no AC reactor 4 (when the power supply impedance is small), and FIG. 6B shows an input current waveform when the AC reactor 4 is inserted (when the power supply impedance is large). Is shown. FIG. 7 shows the characteristics of the input power factor depending on whether or not the AC reactor 4 is inserted. The horizontal axis indicates the output current ratio [%] with respect to the rated output current of the DC power supply device 2, and the vertical axis indicates the input. Represents the power factor.

As can be seen from these figures, generally, when the input current is small and the power supply impedance is small, the input current flows intermittently. Conversely, when the input current is large and the power supply impedance is large, the input current is small. It flows continuously. That is, if the power supply impedance is small, the input power factor is reduced, and a current having a high peak value flows through the rectifier diode of the rectifier circuit 5. As a result, the ripple current flowing through the smoothing capacitor 7 increases, and the ripple voltage of the DC voltage (the voltage across the smoothing capacitor 7) also increases.

At this time, if the system impedance and the phase voltage of the AC power supply 8 are in an unbalanced state, the input current is unbalanced between the phases and the phase current flows to a specific phase.
The peak value of the current flowing through the rectifier diode is further increased, and the ripple current flowing through the smoothing capacitor 7 and the ripple voltage of the DC voltage further increase.

As described above, when the power supply impedance is small, problems such as a reduction in the life of the smoothing capacitor 7 due to the ripple current, superposition of the ripple voltage on the inverter output voltage, and overheating of the rectifier diode are caused. In addition, if the power supply impedance is small, the input power factor is degraded, which causes a harmonic to flow from the DC power supply device 2 to the AC power supply 8. Therefore, in many cases, the AC reactor 4 is used for the purpose of improving the life and reliability of the device and reducing the influence on the power supply side.
And a DC reactor 6 is used.

The smoothing capacitor 7 is a maintenance part having a design life of about 5 to 7 years, and is scheduled to be replaced during use. The life time is most affected by the temperature and varies depending on the magnitude of the ripple current. However, the inverter device 1
Conditions such as environmental conditions, the impedance of the AC power supply 8 itself, the presence or absence of the AC reactor 4 and the DC reactor 6, and the like differ for each user. Therefore, the ambient temperature and the ripple current value of the smoothing capacitor 7 also differ for each user. On the other hand, as a result, there is a problem that it is not possible to specify the replacement time of the smoothing capacitor 7 for maintenance. Therefore, the manufacturer informs each user that it should be replaced in three to five years, which is shorter than the design life, and is forced to perform maintenance in a short cycle even if there is a remaining life. In addition, with the increase in the number of shipped inverter devices 1, the trouble of maintenance work has been increasing.

The present invention has been made in view of the above circumstances, and has as its object to provide a DC power supply device capable of detecting a replacement time based on the life of a smoothing capacitor and further estimating the life of the smoothing capacitor. Is to provide.

[0009]

In order to achieve the above object, a DC power supply according to the present invention supplies a DC voltage obtained by rectifying an AC power supply output by a rectifier circuit and smoothing the output by a capacitor to a load. In the DC power supply device, an environmental condition detecting means for detecting an environmental condition affecting the life of the capacitor and outputting an environmental condition signal, and an expected life time of the capacitor and life characteristics data of the capacitor with respect to the environmental condition are determined in advance. Storage means for storing, an application time detecting means for detecting a voltage application time of the capacitor,
Life detecting means for calculating an elapsed life of the capacitor based on the environmental condition signal, the life characteristic data, and the voltage application time, and outputting an alarm signal based on the elapsed life and the expected life. And an alarm output means for outputting an alarm in response to the alarm signal (claim 1).

With this configuration, the life detecting means can estimate the rate of progress of the deterioration of the capacitor under the respective environmental conditions based on the environmental condition signal and the life characteristic data. The elapsed lifetime of the capacitor can be accurately calculated based on the ratio and the voltage application time. The life detecting means outputs an alarm via the alarm output means based on the elapsed life time and the expected life time, so that the user can know when the life of the capacitor has been reached.

In this case, an alarm signal is output before the elapsed life reaches the expected life (claim 2), or an alarm signal is output when the elapsed life exceeds the expected life (claim 2). It is preferable to configure the life detecting means as described in 3). With such a configuration, the user can know in advance the replacement time of the capacitor before the expected life of the capacitor is reached, and can proceed with operations such as preparation for maintenance (claim 2). Also, the user can know that the capacitor has exceeded the expected life, and thus can stop using the power supply device (claim 3).

Further, when the capacitor is installed, the environmental condition signal at that time, the life characteristic data of the capacitor,
It is preferable to provide a life prediction unit that predicts the life of the capacitor based on the expected life time and outputs the life prediction information.

[0013] With this configuration, the life predicting means predicts the life of the capacitor based on the environmental conditions obtained in a test run or the like when the DC power supply is installed, and outputs the life prediction information. Can preliminarily know the maintenance time of the DC power supply, and if the predicted life is short, it is possible to improve environmental conditions. The life prediction by the life prediction means can be performed not only at the time of installation but also during the operation of the DC power supply (claim 5).

In these cases, it is preferable that the environmental condition detecting means outputs the temperature near the capacitor as the environmental condition signal. With such a configuration, the life detecting means can calculate the elapsed life time based on the relationship between the ambient temperature of the capacitor and the life (for example, Arrhenius law).

It is preferable that the environmental condition detecting means is configured to output the side surface temperature and the near temperature of the capacitor as the environmental condition signal. With such a configuration, the life detecting means can determine the self-heating temperature of the capacitor due to the ripple current based on the side surface temperature and the vicinity temperature of the capacitor, and use the self-heating temperature to calculate the elapsed life time. It is possible to calculate accurately.

Further, the environmental condition detecting means may output the ripple current flowing through the capacitor as the environmental condition signal. With such a configuration,
The life detecting means can calculate a more accurate elapsed life time in consideration of the self-heating temperature of the capacitor caused by the ripple current.

On the other hand, the life estimating means may be configured to detect abnormal heat generation of the capacitor based on the side surface temperature of the capacitor and output an unsuitable signal (claim 9).
With this configuration, the DC power supply device outputs an alarm signal based on the elapsed life time of the capacitor, and directly detects abnormal heating of the capacitor due to phase loss of the AC power supply based on the side surface temperature, and outputs a nonconforming signal. , The safety and reliability are further improved. The load of the DC power supply can be an inverter circuit.
0).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the DC power supply of the present invention is applied to an inverter will be described below with reference to FIGS. In FIG. 1 showing the configuration of the inverter device, an inverter device 11 includes a DC power supply device 12 and an inverter circuit 1.
And 3. This DC power supply device 12 is further configured as follows. That is, for example, the output of each phase of the AC power supply 14 which is a three-phase 200 [V] commercial power supply is input to the rectifier circuit 16 via the AC reactor 15, and the positive side and the negative side which are the outputs of the rectifier circuit 16 are provided. A smoothing capacitor 19, which is an electrolytic capacitor, is connected between the DC power supply lines 17 and 18. A DC reactor 20 is interposed in the DC power supply line 17 from the positive output terminal of the rectifier circuit 16 to the positive terminal of the capacitor 19. Here, the rectifier circuit 16 has a known circuit configuration in which rectifier diodes are connected in a three-phase bridge.

Further, a temperature sensor 21 such as a thermistor is provided around (near) and side surfaces of the capacitor 19, respectively.
And 22 are provided. Further, in order to detect a ripple current flowing through the capacitor 19, a current detector 23 configured using, for example, a Hall element is provided on the DC power supply line 18 reaching the negative terminal of the capacitor 19.

On the other hand, an inverter circuit 13 as a load of the DC power supply 12 is a switching element such as an IGBT.
And a reflux diode are connected in a three-phase bridge to form a well-known circuit configuration. The output terminal of each phase of the inverter circuit 13 is connected to each phase winding terminal of an AC motor, for example, an induction motor 24. In order to detect a phase current (output current), an arbitrary one of the phases, for example, a W-phase output line,
For example, a current detector 25 configured using a Hall element is provided.

Inverter control circuit 26 as an inverter control means for performing all the controls related to the inverter device 11
Is a microcomputer 27 (hereinafter, referred to as a microcomputer 27), a voltage detection circuit 28 as an application time detection means,
Temperature detection circuit 29, ripple current detection circuit 30, output current detection circuit 31, alarm output circuit 3 as alarm output means
2 and a lifetime display circuit 33. Here, the temperature detection circuit 29 and the ripple current detection circuit 30
Functions as environmental condition detecting means together with the temperature sensor 21 and the current detector 23.

Further, the microcomputer 27 includes a parameter setting circuit 34 as storage means, a life detection circuit 35 as life detection means, and a life prediction circuit 3 as life prediction means.
6, a non-conforming output circuit 37, and a drive control circuit 38 as drive control means.

The voltage detection circuit 28 detects a voltage across the capacitor 19 (hereinafter referred to as a DC voltage) by, for example, a resistance voltage dividing circuit (not shown), and detects the detected DC voltage at A.
It is configured to be digitized by a / D converter and output to the life detecting circuit 35 in the microcomputer 27.

The temperature detecting circuit 29 includes the temperature sensors 21 and 2
The ambient temperature (around) and the side temperature of the capacitor 19 respectively detected by step 2 are digitized by an A / D converter, and the side temperature signal and the ambient temperature signal as the environmental condition signal are converted into a life detecting circuit 35 in the microcomputer 27. Output. These temperature signals are also supplied to a life estimation circuit 36 through a life detection circuit 35.

The ripple current detection circuit 30 includes the current detector 2
The ripple current flowing into the capacitor 19 detected by 3 is digitized by an A / D converter, and the ripple current signal is output to the life detection circuit 35 in the microcomputer 27 as an environmental condition signal. This ripple current signal is also supplied to the life estimation circuit 36 through the life detection circuit 35.

The output current detection circuit 31 includes a current detector 25
, The W-phase current (output current) of the induction motor 24 detected by the A / D converter is digitized by the A / D converter, and the output current signal is output to the drive control circuit 38 in the microcomputer 27.

The parameter setting circuit 34 includes a microcomputer 27
It is configured as a non-volatile memory, for example, an EEPROM, and stores life characteristic data of the capacitor 19 with respect to detected environmental conditions (ambient temperature, ripple current value) and the expected life time of the capacitor 19 under certain conditions, that is, a capacitor manufacturer. Is stored in advance.

The life detecting circuit 35 receives the detected DC voltage value from the voltage detecting circuit 28, the ambient temperature and the side surface temperature from the temperature detecting circuit 29, and the ripple current value from the ripple current detecting circuit 30, and sets a parameter. Circuit 34
Enter the expected life time and required life characteristic data from
The elapsed life time from the installation (replacement) of the capacitor 19 is obtained by a calculation described later. However, the side surface temperature is not used for the calculation and is output to the life prediction circuit 36 as it is. The elapsed life time as the calculation result is temporarily stored in a memory in the microcomputer 27, for example, an EEPROM. Further, by comparing the elapsed life time with the expected life time, an alarm signal is output at a predetermined time. Although not shown in FIG.
For example, a reset switch is provided for clearing the elapsed life time to zero.

The alarm output circuit 32 comprises, for example, an alarm lamp or an alarm buzzer.
Is notified to the user that the time to replace the capacitor 19 has come.

The life estimation circuit 36 calculates the elapsed life time input from the life detection circuit 35, the ambient temperature and the ripple current value of the capacitor 19 obtained through the life detection circuit 35,
Based on the required life characteristic data and the expected life time input from the parameter setting circuit 34, the capacitor 19
Is calculated by a calculation described later. further,
The life predicting circuit 36 constantly monitors the side surface temperature of the capacitor 19, and outputs a nonconforming signal when the side surface temperature exceeds a predetermined upper limit temperature.

The nonconforming output circuit 37 includes, for example, the microcomputer 2
7, and outputs the incompatible signal from the life prediction circuit 36 to an external circuit. Further, the life display circuit 33 includes, for example, an LCD display, an LED display, and the like.
The predicted life time input from the life prediction circuit 36 is displayed.

The drive control circuit 38 includes the inverter circuit 13
It is configured to output a PWM-controlled commutation signal to a control terminal (gate terminal) of each switching element. The inverter circuit 13 performs a DC-AC conversion operation according to the commutation signal, and outputs a variable voltage and a variable frequency AC voltage to the induction motor 24 based on a command signal (not shown) externally provided. The induction motor 24 is driven to rotate by this AC voltage.

Next, the operation of the present embodiment will be described with reference to FIGS. Environmental conditions that affect the life of the capacitor 19 include temperature, ripple current, applied voltage, humidity, atmospheric pressure, and vibration. Among them, there is known an experimental result (Arrhenius law) that the influence of the temperature is the largest, and the life is almost halved when the temperature rises by 10 [° C.]. In addition, when a ripple current flows through the capacitor 19, self-heating is generated, and the life is shortened. For other environmental conditions, the effect on the life is small as long as it is used within the allowable value of each environmental condition. Therefore, generally, the life time of the capacitor 19 can be calculated by the following equation.

[0034]

(Equation 1)

Here, L is a rated life time that is guaranteed by the capacitor maker, that is, an expected life time.
There are a type that is guaranteed for 2000 hours at an ambient temperature of 85 ° C. and a type that is guaranteed for 5000 hours at an ambient temperature of 105 ° C. The expected life time is determined in advance by the EEPROM as the parameter setting circuit 34, as described above.
Is stored in Further, the ripple acceleration coefficient Bn is one of the life characteristic data representing the effect of the ripple current on the life.
Although not specifically shown, it has a characteristic that increases as the ripple current increases.

FIG. 2 shows the change over time of the capacitance of the capacitor 19 with the ambient temperature as a parameter.
The horizontal axis represents the voltage application time, and the vertical axis represents the change rate [%] of the capacitance. The characteristics shown here correspond to the above-mentioned 1
It can be seen that the rate of decrease in capacitance increases as the ambient temperature rises for the type of 05 [° C.] / 5000 hours.

The method of calculating the elapsed life time in the life detecting circuit 35 will be described below. The life detection circuit 35 detects the presence or absence of voltage application to the capacitor 19 by comparing the DC voltage value input from the voltage detection circuit 28 with a preset application determination voltage value. That is, when the DC voltage value is equal to or higher than the application determination voltage value, it is determined that the voltage is applied to the capacitor 19, and the application time counter provided in the microcomputer 27 determines that the capacitor 1
The time during which the capacitor 19 is in the voltage application state after the replacement of the capacitor 9 is integrated as the voltage application time.

The life detecting circuit 35 inputs the ambient temperature of the capacitor 19 from the temperature detecting circuit 29 at regular intervals of the accumulated voltage application time, for example, every hour, and further outputs the ripple current from the ripple current detecting circuit 30. Enter a value. At this time, the life detection circuit 35 adds (that is, integrates) the addition time obtained based on the ambient temperature, the ripple current value, and the life characteristic data stored in the parameter setting circuit 34 to the elapsed life time. This addition time is one hour, which is the same as the addition cycle when a rated ripple current is flowing under a reference environment condition, for example, an ambient temperature of 105 [° C.], but when the ambient temperature and the ripple current value are different from this reference environment condition. Increases or decreases accordingly, as described below.

FIG. 3 shows the calculation result of the above equation (1). The horizontal axis represents the ratio of the ripple current value actually flowing to the rated ripple current value (current multiple), and the vertical axis represents the rated life. The ratio (estimated life time coefficient) of the life time Ln by the equation (1) to the time L is expressed as a logarithm. The data shown in FIG. 3 is stored in the parameter setting circuit 34 in advance as life characteristic data. The above-mentioned addition time is based on the estimated life time coefficient when the ambient temperature is 105 [° C.] and the current multiple is 1 in FIG. 3 (= 1).
It can be obtained as the reciprocal of the estimated life time coefficient at the actual ambient temperature and the ripple current value. In this case, without using the life characteristic data shown in FIG. 3, it is also possible to directly calculate by using the equation (1).

The elapsed life time of the capacitor 19 obtained in this manner is not lost even if the inverter control circuit 26 is in a cut-off state.
Stored in the OM. When the capacitor 19 is replaced, the elapsed life time is cleared to 0 by operating a reset switch (not shown).

Further, the life detecting circuit 35 calculates the elapsed life time for each hour, and then calculates the estimated life time stored in the parameter setting circuit 34 (for example, 5 hours).
000 hours), an alarm signal is output if the elapsed life time exceeds the expected life time. Therefore, the user of the inverter device 11 can know the replacement time of the capacitor 19 from the alarm lamp or the alarm buzzer of the alarm output circuit 32. In this case, an alarm signal may be output in advance when the elapsed life time approaches the expected life time.

Next, a method of estimating the life in the life estimating circuit 36 will be described below. The life predicting circuit 36 is configured based on the environmental conditions at that time, that is, the ambient temperature of the capacitor 19 and the ripple current value at the time of installing the capacitor 19 (at the time of replacement) or at any time during the operation of the inverter device 11 (current time). The remaining lifetime (predicted lifetime) of the capacitor 19 is predicted. For example, when a test run of the inverter device 11 is performed at the time of replacement of the capacitor 19, the life prediction circuit 36 inputs the data (see FIG. 3) relating to the estimated life time coefficient from the parameter setting circuit 34 and outputs the ambient temperature during the test run. And an estimated life time coefficient for the ripple current value. Then, the expected life time is estimated by multiplying the expected life time (for example, 5000 hours) by the estimated life time coefficient. In this case, without using the life characteristic data shown in FIG.
It is also possible to obtain by direct calculation using equation (1).

During the operation of the inverter device 11, the estimated life time estimated by the above method is
The predicted life time can be estimated by subtracting the time obtained by multiplying the elapsed life time calculated by the life detection circuit 35 by the estimated life time coefficient at that time. The life time information predicted in this way is displayed on an LCD display or an LED display constituting the life display circuit 33.

Further, the life prediction circuit 36 operates to input the side surface temperature of the capacitor 19 through the life detection circuit 35 and to output an incompatibility signal when the side surface temperature exceeds a predetermined upper limit temperature. Therefore, the inverter device 11
In the case where a phase loss occurs in the input of the capacitor 19 or the like, even if the deterioration of the capacitor 19 progresses at an abnormal speed due to an increase in the ripple current, the user cannot use the non-conforming output circuit 37.
Overheating of the capacitor 19 can be known through the line.

The output current value detected by the output current detection circuit 31 is used by the drive control circuit 38 to protect the inverter circuit 13 and the induction motor 24 from overcurrent. In this case, the ripple current flowing through the capacitor 19 tends to increase as the output current increases. Therefore, the life detecting circuit 35 outputs the current instead of the ripple current value detected using the current sensor 23 and the ripple current detecting circuit 30. A configuration may be adopted in which a current value is input and a ripple current value is estimated from the output current value.

As described above, in order to detect the life of the capacitor 19 used in the DC power supply 12 of the inverter device 11 of the present embodiment, the life detection circuit 35 is used.
, The environmental conditions, that is, the capacitors 19 every hour.
Is characterized by detecting the ambient temperature and the ripple current value and calculating the elapsed life time in consideration of the environmental conditions for each hour by referring to the estimated life time coefficient stored in the parameter setting circuit 34 in advance. Have. Then, the life detection circuit 35 compares the elapsed life time with the expected life time guaranteed by the manufacturer to warn the user that the replacement time of the capacitor 19 has been reached or is near to the replacement time. The user only has to replace the capacitor 19 in accordance with the alarm, which simplifies the management of the maintenance time and reduces the risk of accidentally missing the replacement time. In particular, since the main life detection is performed by reflecting the environmental condition every one hour, the life span detection accuracy is high and the alarm timing has high reliability.

The life predicting circuit 36 of the inverter device 11 detects the ambient temperature and the ripple current value at the time of replacement of the capacitor 19 or at the time of the subsequent operation, and predicts the current by referring to the estimated life time coefficient. The life time is calculated and displayed on the life display circuit 33. Therefore, the user can grasp the maintenance time of the capacitor 19 in advance, and if the predicted life time is short, it is possible to improve environmental conditions such as temperature and ripple current.

Further, the life prediction circuit 36 outputs a nonconforming signal via the nonconforming output circuit 37 when the side surface temperature of the capacitor 19 exceeds a predetermined upper limit temperature, so that the reliability and safety of the inverter device 11 are improved. Is further improved. In this case, the configuration may be such that the non-conforming signal is input to the drive control circuit 38, and the inverter circuit 13 is stopped at the same time as the non-conforming signal is output.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 4 with respect to portions different from the first embodiment. In FIG. 1, except for the temperature sensor 23 and the ripple current detection circuit 30, the configuration is such that the side surface temperature of the capacitor 19 is used as an environmental condition instead. In this case, the temperature sensors 21 and 22 and the temperature detecting circuit 29 serve as environmental condition detecting means. In this configuration, the calculation of the elapsed life time in the life detection circuit 35 is performed as follows.

As described above, the biggest factor affecting the life of the capacitor 19 is the temperature, and the ripple current also reduces the life as an increase in the center temperature due to self-heating generated inside the capacitor 19. In this case, it is most accurate to detect the center temperature of the capacitor 19 and determine the difference between the center temperature and the ambient temperature as the self-heating temperature. However, since it is difficult to directly detect the center temperature, the center temperature is estimated from the ambient temperature and the side surface temperature of the capacitor 19.

FIG. 4 is a diagram showing the relationship between the diameter φ [mm], which is the external dimension of the capacitor 19, and the temperature difference coefficient. The temperature difference coefficient is a ratio between a temperature difference obtained by subtracting the ambient temperature from the side temperature and a temperature difference obtained by subtracting the ambient temperature from the center temperature, that is, a self-heating temperature, and is stored in the parameter setting circuit 34 in advance as life characteristic data. Is what is being done.

The microcomputer 27 sets the temperature difference coefficient corresponding to the outer shape of the capacitor 19 at the time of initialization to the parameter setting circuit 3.
4 For example, by reading from an EEPROM,
5 is written into the RAM. Thereafter, the life detection circuit 35 inputs the ambient temperature and the side surface temperature as an environmental condition signal at regular intervals, for example, every hour of the voltage application time obtained by integration, and calculates the difference between the ambient temperature and the side surface temperature (> 0). ) Is multiplied by the temperature difference coefficient to determine the self-heating temperature. Then, although not specifically shown, the estimated life time coefficient is obtained based on life characteristic data indicating the relationship between the self-heating temperature and the estimated life time coefficient using the ambient temperature as a parameter.
The life characteristic data is stored in the parameter setting circuit 34 in advance. The subsequent calculation method of the elapsed life time is the same as in the first embodiment. The life prediction circuit 3
6 can also be calculated in the same manner as in the first embodiment, using the estimated life time coefficient based on the self-heating temperature described above.

As described above, in the inverter device 11 of the present embodiment, the self-heating temperature is calculated by multiplying the difference between the ambient temperature and the side surface temperature of the capacitor 19 by the temperature difference coefficient every hour in the life detecting circuit 35. The estimated life time coefficient is obtained based on life characteristic data indicating the relationship between the self-heating temperature and the estimated life time coefficient, and the elapsed life time is obtained. Further, the estimated life time in the life estimation circuit 36 is also estimated based on the self-heating temperature.

Therefore, in this embodiment, the same effects as those of the first embodiment can be obtained for the life detection and the life prediction, and the current sensor 23 and the ripple current detection circuit 30 for detecting the ripple current become unnecessary. A simple configuration can be provided.

(Other Embodiments) The present invention is not limited to the embodiment described above and shown in the drawings.
For example, the configuration may be as follows. Life detection circuit 35
The environmental condition used in the life prediction circuit 36 may be only the ambient temperature of the capacitor 19. In this case, the parameter setting circuit 34 may store the life characteristic data calculated by setting the ripple acceleration coefficient Bn to 1 in the equation (1). In the first and second embodiments, the operation cycle of the life detecting means 35 is not limited to one hour, and may be determined as appropriate according to the installation environment, operating conditions, and the like of the inverter device 11.

[0056]

As described above, in the DC power supply of the present invention, the life characteristic data for the environmental condition affecting the life of the smoothing capacitor is stored in advance, and the detected environmental condition, life characteristic data, And calculating the elapsed life time of the capacitor based on the voltage application time of the capacitor and outputting an alarm signal based on the elapsed life time and the expected life time. In this case, in the calculation of the elapsed life time, environmental conditions at each time are reflected based on the life characteristic data with respect to the elapse of the voltage application time.
It has an excellent effect that the life detection accuracy is good and the reliability of the warning period is high. Therefore, the management of the maintenance time is simplified, and the risk of accidentally missing the replacement time is reduced.

Further, when the present DC power supply is installed or operated, the life of the capacitor is predicted based on the environmental conditions, life characteristics data, expected life and elapsed life at that time. The user can know the maintenance time of the capacitor in advance, and if the predicted life is short, it is possible to improve the environmental conditions. Furthermore, the present DC power supply device detects abnormal heating of the capacitor based on the side surface temperature of the capacitor and outputs a non-conforming signal, so that its reliability and safety are further improved.

[Brief description of the drawings]

FIG. 1 is an electrical configuration diagram of an inverter device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a change in capacitance of a capacitor over time;

FIG. 3 is a diagram showing an estimated life time coefficient with respect to an ambient temperature and a current multiple of a capacitor.

FIG. 4 is a diagram showing a temperature difference coefficient with respect to an outer dimension (diameter) of a capacitor according to a second embodiment of the present invention.

FIG. 5 is a diagram corresponding to FIG. 1 in a conventional configuration.

FIG. 6 is an input current waveform diagram when there is no AC reactor (a) and when there is an AC reactor (b).

FIG. 7 is a diagram showing characteristics of an input power factor with respect to an output current.

[Explanation of symbols]

11 is an inverter device, 12 is a DC power supply device, 13 is an inverter circuit (load), 14 is an AC power supply, 16 is a rectifier circuit, 19 is a capacitor, 21, 23, 29, and 30 are environmental condition detecting means, and 28 is voltage detection. Circuit (application time detection means), 32 is an alarm output circuit (alarm output means), 34 is a parameter setting circuit (storage means), 35 is a life detection circuit (life detection means), 36 is a life prediction circuit (life prediction means) It is.

Claims (10)

[Claims] 1. A DC power supply device that rectifies an AC power supply output with a rectifier circuit and supplies a DC voltage obtained by smoothing the output with a capacitor to a load, wherein an environmental condition affecting the life of the capacitor is detected. Environmental condition detecting means for outputting an environmental condition signal; storage means for storing in advance the expected life time of the capacitor and the life characteristic data of the capacitor with respect to the environmental condition; and application time detecting means for detecting the voltage application time of the capacitor. Life detection for calculating an elapsed life time of the capacitor based on the environmental condition signal, the life characteristic data, and the voltage application time, and outputting an alarm signal based on the elapsed life time and the expected life time. Means, and an alarm output means for outputting an alarm in response to the alarm signal. Power supply. 2. The DC power supply according to claim 1, wherein the life detecting means outputs an alarm signal before the elapsed life reaches the expected life. 3. The DC power supply according to claim 1, wherein the life detecting means outputs an alarm signal when the elapsed life time exceeds the expected life time. 4. A life predicting means for predicting the life of the capacitor and outputting the life prediction information based on the environmental condition signal, the life characteristic data of the capacitor and the expected life time at the time of installing the capacitor. The DC power supply according to claim 1, further comprising: 5. A life prediction means for predicting the life of the capacitor and outputting the life prediction information at the present time based on the environmental condition signal, the life characteristic data of the capacitor, the expected life time, and the elapsed life time at that time. The DC power supply according to claim 1, further comprising: 6. The DC power supply according to claim 1, wherein the environmental condition detecting means outputs a temperature near the capacitor as an environmental condition signal. 7. The DC power supply device according to claim 1, wherein the environmental condition detecting means outputs a side surface temperature and a nearby temperature of the capacitor as an environmental condition signal. 8. The DC power supply according to claim 1, wherein the environmental condition detecting means outputs a ripple current flowing through the capacitor as an environmental condition signal. 9. The DC power supply device according to claim 4, wherein the life estimating unit detects abnormal heat generation of the capacitor based on a side surface temperature of the capacitor and outputs an unsuitable signal. 10. The DC power supply according to claim 1, wherein the load is an inverter circuit.