JP7241590B2 - Condition Diagnosis Device, Condition Diagnosis Method, and Condition Diagnosis Program - Google Patents

Description

The present invention relates to a state diagnosis device, a state diagnosis method, and a state diagnosis program capable of diagnosing the state of a smoothing capacitor in a power supply device having a rectifier circuit and a smoothing capacitor.

2. Description of the Related Art Conventionally, switching power supply circuits have been widely used in power supply devices for electrical equipment, and the life of such switching power supply circuits greatly affects the reliability of the electrical equipment. The life of the switching power supply circuit greatly affects the deterioration of the smoothing capacitor arranged on the primary side. Therefore, such a smoothing capacitor is often the object of maintenance and inspection of equipment, and has a great impact on the reduction of maintenance costs and the optimization of equipment operation.

Therefore, for example, Patent Literature 1 proposes a power supply device that determines the life of a smoothing capacitor. The power supply device described in Patent Document 1 determines the life of the smoothing capacitor based on the result of comparing the peak value of the instantaneous value of the current flowing to the smoothing capacitor that smoothes the voltage rectified by the rectifier circuit with the determination reference value. .

JP 2011-106987 A

However, in the technique described in Patent Document 1, since it is necessary to provide a current measuring unit that measures the current flowing between the rectifier circuit and the smoothing capacitor inside the power supply, It is difficult to apply the technology described in Patent Document 1 to the power supply device of

SUMMARY OF THE INVENTION It is an object of the present invention to provide a condition diagnosis device capable of diagnosing at least one of deterioration and service life of a smoothing capacitor from the outside of a power supply device having a rectifying circuit and a smoothing capacitor. With the goal.

In order to solve the above-described problems and achieve the object, the condition diagnosis device of the present invention includes a current measurement section, a voltage phase calculation section, and a diagnosis section. The current measurement unit measures an instantaneous value of current between the power supply and an AC power supply that supplies AC power to the power supply including a rectifying circuit and a smoothing capacitor. The voltage phase calculator calculates the voltage phase of the AC power supply at a first timing when the supply of AC power from the AC power supply to the rectifier circuit is started. The diagnosis unit calculates a current moving average value, which is a moving average value of magnitudes of instantaneous values measured by the current measurement unit during the first period from the first timing, during a second period longer than the first period. , the current moving average peak value, which is the peak value of the current moving average value in the second period, is calculated a plurality of times when determining the deterioration state of the smoothing capacitor, and the voltage phase when determining the deterioration state of the smoothing capacitor is calculated. A first relationship, which is a relationship between one voltage phase and a first current moving average peak value that is a current moving average peak value at the time of determining the deterioration state of the smoothing capacitor, is acquired, and the first current moving average peak value in the first relationship is acquired. Diagnosing at least one of smoothing capacitor degradation and life based on the overall decrease over time .

ADVANTAGE OF THE INVENTION According to this invention, it is effective in the ability to diagnose at least one of deterioration and lifetime of a smoothing capacitor from the outside of the power supply device which has a rectifier circuit and a smoothing capacitor.

FIG. 4 is a diagram for explaining state diagnosis processing by the state diagnosis device according to the first embodiment of the present invention; 1 is a diagram showing a configuration example of electrical equipment according to a first embodiment; FIG. FIG. 2 is a diagram showing a specific configuration example of the condition diagnosis device according to the first embodiment; FIG. 4 is a diagram showing an example of a waveform of inrush current to the power supply device according to the first embodiment; FIG. 10 is a diagram showing an example of temporal change in current moving average value according to the first embodiment; FIG. 4 is a diagram showing an example of temporal changes in each of a voltage phase, a current moving average value, and a current moving average peak value when the voltage phase is 0 degrees at power-on timing according to the first embodiment; FIG. 10 is a diagram showing an example of temporal changes in each of the voltage phase, current moving average value, and current moving average peak value when the voltage phase is 90 degrees at power-on timing according to the first embodiment; 4 is a diagram showing the relationship between the voltage phase and current moving average peak value at power-on timing according to the first embodiment; FIG. FIG. 4 is a diagram showing the relationship between the voltage phase and current moving average peak value at power-on timing when the capacitance of the smoothing capacitor changes according to the first embodiment; FIG. 4 is a diagram showing an example of the relationship between the current moving average peak value average value and the capacitance of the smoothing capacitor according to the first embodiment; FIG. 4 is a diagram showing an example of the relationship between the current moving average peak value average value, the resistance value of the inrush current limiting resistor, and the capacitance of the smoothing capacitor according to the first embodiment; 4 is a diagram showing a configuration example of a current characteristic calculation unit according to the first embodiment; FIG. 4 is a diagram showing a configuration example of a determination unit according to the first embodiment; FIG. 3 is a flow chart showing an example of processing by the diagnosis unit of the condition diagnosis device according to the first embodiment; 4 is a flowchart showing an example of initial characteristic calculation processing according to the first embodiment; Flowchart showing an example of deterioration life determination processing according to the first embodiment 4 is a flowchart showing another example of deterioration life determination processing according to the first embodiment; FIG. 2 is a diagram showing an example of a hardware configuration of a diagnosis unit in the condition diagnosis device according to the first embodiment; FIG.

A condition diagnosis device, a condition diagnosis method, and a condition diagnosis program according to embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

Embodiment 1.
FIG. 1 is a diagram for explaining state diagnosis processing by a state diagnosis device according to Embodiment 1 of the present invention. As shown in FIG. 1 , the condition diagnosis device 1 according to the first embodiment is arranged between an AC power supply 2 and electrical equipment 3 .

The AC power supply 2 supplies AC power to the electrical equipment 3 . The electrical equipment 3 has a rectifier circuit 41 and a smoothing capacitor 42 on the primary side, a power supply 4 that converts AC power supplied from the AC power supply 2 into DC power, and a load to which the DC power is supplied from the power supply 4. 5. The load 5 includes, for example, electrical or motorized components, and consumes power to perform the functions of the electrical equipment 3 . Such a load 5 partially includes, for example, a switching element, a switching transformer, a secondary-side diode, and a secondary-side smoothing capacitor. A part of the load 5, the rectifying circuit 41 and the smoothing capacitor 42 constitute a switching power supply circuit.

The power supply device 4 includes an inrush current limiting resistor 43 and a switch 44 . Rush current limiting resistor 43 is arranged between rectifier circuit 41 and smoothing capacitor 42 to limit the rush current to smoothing capacitor 42 . Note that the inrush current limiting resistor 43 is not limited to the position shown in FIG. 1 as long as it can limit the inrush current to the smoothing capacitor 42 .

The switch 44 opens and closes the electric circuit between the AC power supply 2 and the rectifier circuit 41 . Opening and closing of the electric circuit by the switch 44 is performed manually or automatically, for example. When the switch 44 is switched from the open state to the closed state, supply of AC power from the AC power supply 2 to the power supply device 4 is started. The power supply device 4 converts AC power supplied from the AC power supply 2 into DC power and supplies the converted DC power to the load 5 . Thereby, the electric equipment 3 will be in an operating state. Hereinafter, for example, the timing at which the switch 44 is switched from the open state to the closed state is referred to as power-on timing.

FIG. 2 is a diagram illustrating a configuration example of electrical equipment according to the first embodiment. In the example shown in FIG. 2 , the rectifier circuit 41 of the power supply device 4 is a full-wave rectifier circuit configured by a diode bridge circuit, and performs full-wave rectification of the AC voltage output from the AC power supply 2 . In addition, the rectifier circuit 41 is not limited to the example shown in FIG.

Returning to FIG. 1, the description of the condition diagnosis device 1 is continued. The condition diagnosis device 1 includes a current transformer 10 , a current measurement section 11 , a voltage measurement section 12 and a diagnosis section 13 . The current transformer 10 is attached to a wire that connects the AC power supply 2 and the power supply device 4 . Based on the output of the current transformer 10, the current measurement unit 11 measures the instantaneous value of the current between the AC power supply 2 and the power supply device 4 at preset intervals.

The voltage measurement unit 12 measures the instantaneous value of the voltage output from the AC power supply 2 to the power supply device 4 at preset intervals. Diagnosis section 13 diagnoses deterioration and life of smoothing capacitor 42 based on the instantaneous value of current measured by current measurement section 11 and the instantaneous value of voltage measured by voltage measurement section 12 .

When the supply of AC power from the AC power supply 2 to the power supply device 4 is started, charging of the smoothing capacitor 42 in the power supply device 4 is started, and a rush current flows through the smoothing capacitor 42 . Therefore, a current corresponding to the inrush current flows between the AC power supply 2 and the power supply device 4 , and the instantaneous value of this current is measured by the current measurement unit 11 . Hereinafter, the instantaneous value of the current measured by the current measuring section 11 will be referred to as the instantaneous current value _id , and the instantaneous value of the voltage measured by the voltage measuring section 12 will be referred to as the instantaneous voltage value _vd .

The diagnosis unit 13 calculates a period integration value Ida, which is a value obtained by squaring the current instantaneous value _id measured by the current measurement unit 11 and integrating _{the value} over a preset period T. Specifically, the diagnosis unit 13 squares each of a plurality of instantaneous current values _id measured by the current measurement unit 11 during a preset period T, and integrates the squared values to obtain a period integration value. Determine the value _Ida .

Since the AC power supplied from the AC power supply 2 is used to charge the smoothing capacitor 42 immediately after the supply of AC power from the AC power supply 2 to the power supply device 4 is started, the period integrated value _Ida It becomes a value corresponding to the inrush current of 42. This inrush current depends on the capacitance of the smoothing capacitor 42, the inrush current limiting resistor 43, and the phase of the AC voltage of the AC power supply 2 at the power-on timing. Hereinafter, the phase of the alternating voltage of the alternating current power supply 2 is described as a voltage phase.

As the smoothing capacitor 42 is repeatedly charged and discharged, the smoothing capacitor 42 deteriorates and the capacitance of the smoothing capacitor 42 decreases. small enough to be ignored. Therefore, if the voltage phase does not change at power-on timing, the rush current mainly depends on the capacitance of the smoothing capacitor 42 .

Therefore, the diagnosis unit 13 calculates a period integration value Ida, which is a value obtained by squaring the current instantaneous value _id measured by the current measurement unit 11 and integrating _it for a preset period T, and calculates the period integration value Ida. Deterioration and life of the smoothing capacitor 42 are diagnosed based on _da .

Since the current measurement unit 11 measures the current between the AC power supply 2 and the power supply device 4 instead of the current inside the power supply device 4, the condition diagnosis device 1 detects deterioration of the smoothing capacitor 42 from the outside of the power supply device 4. and can diagnose longevity.

When the voltage phase changes at power-on timing, the rush current also changes according to the voltage phase at power-on timing. Therefore, the diagnosis unit 13 determines the voltage phase at the power-on timing based on the voltage instantaneous value _vd measured by the voltage measurement unit 12, and determines the voltage phase at the power-on timing and the period integrated value _Ida . Based on this, the deterioration and life of the smoothing capacitor 42 are diagnosed. Hereinafter, the voltage phase at power-on timing may be referred to as voltage phase _θon .

The electrical equipment 3 has a function of outputting an ON signal indicating the power-on timing, and the diagnostic unit 13 determines the voltage phase at the timing when the ON signal is output from the electrical equipment 3 as the voltage phase θ _on . can do.

The AC power supply 2 has a switch 6 inside, and an AC voltage is output from the AC power supply 2 when the switch 6 is switched from an open state to a closed state. The AC power supply 2 has a function of outputting an ON signal indicating the timing at which the switch 6 switches from the open state to the closed state. For example, when the switch 44 is closed, the diagnosis unit 13 can determine the voltage phase at the timing when the ON signal is output from the AC power supply 2 as the voltage phase _θon .

In this manner, the diagnostic unit 13 can determine the voltage phase θ _on based on the ON signal from the AC power supply 2 or the electrical equipment 3 . Then, the diagnosis unit 13 diagnoses deterioration and life of the smoothing capacitor 42 based on the voltage phase _θon and the period integrated value _Ida . Therefore, the condition diagnosis device 1 can diagnose the deterioration and life of the smoothing capacitor 42 even when the voltage phase θ _on changes.

If the voltage phase does not change at power-on timing, the condition diagnosis device 1 may be configured without the voltage measurement unit 12 . For example, when the switch 6 changes from an open state to a closed state at the zero cross point of the AC voltage of the AC power supply 2, or when the switch 44 changes from the open state to the closed state at the zero cross point of the AC voltage of the AC power supply 2 in the electric equipment 3 In this case, the condition diagnosis device 1 may be configured without the voltage measurement section 12 .

The configuration of the condition diagnosis device 1 will be specifically described below. FIG. 3 is a diagram illustrating a specific configuration example of the condition diagnosis device according to the first embodiment; As shown in FIG. 3 , the condition diagnosis device 1 includes a current transformer 10 , a current measurement section 11 , a voltage measurement section 12 and a diagnosis section 13 . Diagnosis unit 13 includes calculation unit 21 , storage unit 22 , and determination unit 23 .

As described above, when the voltage phase _θon changes, the inrush current changes depending on the voltage phase _θon . That is, the waveform of the rush current to the smoothing capacitor 42 changes greatly depending on the voltage phase _θon . Therefore, the calculation unit 21 calculates the period integrated value _Ida , which is a value obtained by accumulating the value obtained by squaring the current instantaneous value _id in a preset period T, and based on the period integrated value _Ida , the smoothing capacitor Diagnose the deterioration and life of 42. As a result, deterioration and life of the smoothing capacitor 42 can be accurately diagnosed from the outside of the power supply device 4 .

Here, the characteristics of the inrush current will be described. Assume that the AC voltage v(t) of the AC power supply 2 input to the electrical equipment 3 at time t is represented by the following equation (1).

The current flowing at power-on timing is controlled by a rectifying circuit 41, a rush current limiting resistor 43, and a smoothing capacitor . The value of the voltage v'(t) output from the rectifier circuit 41 by the diode bridge of the rectifier circuit 41 becomes an absolute value as shown in the following equation (2). It is assumed that the voltage drop due to the diode bridge is negligibly small compared to the AC voltage v(t).

Here, let the resistance value of the rush current limiting resistor 43 be "R", the load 5 of the electrical equipment 3 be "R ₀ ", and the capacitance of the smoothing capacitor 42 be "C". Further, the currents flowing through the inrush current limiting resistor 43, the load 5, and the smoothing capacitor 42 at time t are defined as "i(t)", " _iC (t)", and " _iR0 (t)", respectively, and the smoothing Let the charge on the capacitor 42 be "q(t)". In this case, the following circuit equations (3) to (6) hold.

A differential equation of the following equation (7) is established from the above equations (3) to (6).

When v′(t)<q(t)/C, the current does not flow from the power supply 4 to the AC power supply 2 due to the diode bridge that constitutes the rectifier circuit 41, so the charge q of the smoothing capacitor 42 in the load 5 (t) is only consumed. Therefore, it is necessary to solve differential equations in the states of v'(t)<q(t)/C and v'(t)>q(t)/C respectively.

Assuming that the initial value of the charge in the smoothing capacitor 42 is “Q ₀ ” and the time elapsed from the power-on timing is “t”, the charge of the smoothing capacitor 42 is q(t) is represented by the following formula (8). In the following formula (8), φ is represented by the following formula (9).

Further, if the initial value of the charge q(t) of the smoothing capacitor 42 is "Q' ₀ ", the charge q(t) of the smoothing capacitor 42 during the period of v'(t)<q(t)/C is It is represented by the following formula (10).

4 is a diagram illustrating an example of a waveform of rush current to the power supply device according to the first embodiment; FIG. The example shown in FIG. 4 shows the case where θ _on =0, that is, the voltage phase at power-on timing is 0 degrees. As shown in FIG. 4, the current i(t) has a waveform with peaks at intervals corresponding to the frequency of v'(t), and the peak value decreases over time. Note that the current i(t) shown in FIG. 4 can be obtained by differentiating the charge q(t). In addition, in the example shown in FIG. 4, the power-on timing is set to "0".

Even if the voltage phase θ _on is the same, when the capacitance of the smoothing capacitor 42 decreases due to deterioration, each peak value of the current i(t) also decreases. Therefore, for example, deterioration of the smoothing capacitor 42 can be determined from the degree of decrease in the peak value of the current i(t) that appears first. However, the waveform of the current i(t) changes with the voltage phase θ _on . Therefore, if the voltage phase θ _on cannot be made the same, it is difficult to determine deterioration of the smoothing capacitor 42 from the degree of decrease in the peak value of the current i(t).

Therefore, the diagnosis unit 13 squares each of the plurality of instantaneous current values _id measured by the current measurement unit 11 in a preset period T, and integrates the plurality of squared values to obtain the period integrated value _Ida Ask for Then, the diagnosis unit 13 divides the integrated period value _Ida by a preset period T, and calculates the square root of the division result. For example, the diagnosis unit 13 uses a plurality of current instantaneous values _id measured by the current measurement unit 11 in a preset period T to calculate the following formula (11).

Since the diagnosis unit 13 repeatedly calculates the above formula (11) each time the instantaneous current value _id is measured, the value _Ir calculated by the above formula (11) is the current instantaneous value in the preset period T. It can be called a moving average of the magnitude of the value _id . Hereinafter, the value _Ir calculated by the above formula (11) will be referred to as the current moving average value _Ir .

The current instantaneous value i _d is measured by the current measuring unit 11 at a cycle of 4 kHz, for example. The preset period T is, for example, 25 ms. Note that the preset period T may be longer than one cycle of the AC voltage waveform output from the AC power supply 2, and is not limited to 25 ms, and may be 20 ms, for example. Moreover, the measurement period of the current instantaneous value _id by the current measurement unit 11 does not have to be 4 kHz.

FIG. 5 is a diagram showing an example of temporal change in current moving average value according to the first embodiment. As shown in FIG. 5, the time change of the current moving average value _Ir has a mountain-shaped characteristic. The diagnosis unit 13 can calculate the peak value of the current moving average value _Ir that is repeatedly calculated. Hereinafter, the peak value of the current moving average value _Ir is referred to as the current moving average peak value _Irp .

Since the time change of the current moving average value _Ir varies depending on the voltage phase _θon , the time change of the current moving average peak value _Irp also varies depending on the voltage phase _θon .

FIG. 6 is a diagram showing an example of temporal changes in each of a voltage phase, a current moving average value, and a current moving average peak value when the voltage phase is 0 degrees at power-on timing according to the first embodiment. . FIG. 7 is a diagram showing an example of temporal changes in each of a voltage phase, a current moving average value, and a current moving average peak value when the voltage phase is 90 degrees at power-on timing according to the first embodiment. . FIG. 8 is a diagram showing the relationship between the voltage phase and current moving average peak value at power-on timing according to the first embodiment.

As shown in FIGS. 6 and 7, the time change of the current i(t) differs greatly between when θ _on =0 degrees and when θ _on =90 degrees. As shown in FIGS. 6 and 7, it can be seen that the change in the current moving average value _Ir due to the change in the voltage phase _θon is suppressed compared to the time change in the current i(t).

Also, as shown in FIG. 8, the current moving average peak value _Irp has a mountain-shaped characteristic that changes with changes in the voltage phase _θon , and it can be seen that changes due to changes in the voltage phase _θon are suppressed. . Note that the example shown in FIG. 8 shows changes in the current moving average peak value _Irp with respect to changes in the voltage phase _θon from 0 degrees to 180 degrees. The change in the current moving average peak value _Irp with respect _to the voltage phase θon changing from 180 degrees to 360 degrees is the same as the change in the current moving average peak value _Irp with respect to the voltage phase θon changing _from 0 degrees to 180 degrees. is.

As the electrical equipment 3 is repeatedly started and stopped, the smoothing capacitor 42 in the power supply device 4 is repeatedly charged and discharged, and the electrostatic capacity of the smoothing capacitor 42 decreases due to deterioration. When the capacitance of the smoothing capacitor 42 decreases, the amount of charge that can be charged in the smoothing capacitor 42 also decreases, so the inrush current at power-on also decreases.

FIG. 9 is a diagram showing the relationship between the voltage phase and current moving average peak value at power-on timing when the capacitance of the smoothing capacitor changes according to the first embodiment. 9, the voltage phase θ _on and current moving average peak value I _rp is shown.

As shown in FIG. 9, when the capacitance of the smoothing capacitor 42 decreases, the mountain-shaped characteristic decreases as a whole. Therefore, the diagnostic unit 13 detects deterioration of the smoothing capacitor 42 based on the current moving average peak value _Irp and the voltage phase _θon . For example, the diagnosis unit 13 can determine the deterioration of the smoothing capacitor 42 from the overall reduction amount or reduction rate of the relationship between the voltage phase _θon and the current moving average peak value _Irp .

Diagnosis unit 13 performs approximation processing for approximating the relationship between voltage phase θ _on and current moving average peak value I _rp based on a plurality of current moving average peak values I _rp obtained at power-on timings at different voltage phases. conduct. Through such approximation processing, the diagnosis unit 13 can calculate the approximate expression _Fvc representing the relationship between the voltage phase _θon and the current moving average peak value _Irp . The approximation formula _Fvc is, for example, a formula that approximates the characteristics shown in FIG. The diagnosis unit 13 can perform the approximation process by, for example, polynomial approximation or the method of least squares. Further, the diagnosis unit 13 can calculate an approximate expression _Fvc representing the relationship between the voltage phase _θon and the current moving average peak value _Irp by interpolation processing instead of approximation processing.

For example, if the electric equipment 3 is turned on once a day, the diagnosis unit 13 obtains a set of the voltage phase θ _on and the current moving average peak value I _rp for each day on the 20th. Thereby, the diagnosis unit 13 can obtain 20 sets of combinations of the voltage phase θ _on and the current moving average peak value I _rp . The diagnosis unit 13 performs approximation processing or interpolation processing from the 20 sets of information to calculate an approximation formula _Fvc representing the relationship between the voltage phase _θon and the current moving average peak value _Irp .

Each voltage phase θ _on will generally be a random voltage phase if the power-on in the electrical equipment 3 cannot be performed such that the power-on timing is at a particular voltage phase. In this case, it is unlikely that the 20-day voltage phase θ _on will be evenly spaced. Therefore, there is a possibility that the approximation formula diverges so that the characteristics at both ends of the voltage phase from 0 degrees to 180 degrees diverge from the true values.

Therefore, the diagnostic unit 13 stores information indicating the tendency of the voltage phase θ _on to both ends. Diagnosis unit 13 determines voltage phase θ _on and current moving average peak value I _rp based on information on a plurality of sets of voltage phase θ _on and current moving average peak value I rp and information on the tendency of voltage phase θ _on to both ends. It is possible to calculate an approximation F _vc representing the relationship with _rp . Accordingly, it is possible to accurately calculate the approximate expression _Fvc representing the relationship between the voltage phase _θon and the current moving average peak value _Irp .

The diagnosis unit 13 can determine the deterioration and life of the smoothing capacitor 42 based on the approximate expression _Fvc representing the relationship between the voltage phase _θon and the current moving average peak value _Irp . Specifically, the diagnosis unit 13 sets the calculated approximation formula F _vc as the initial approximation formula FB _vc in the initial state determination mode. After that, the diagnosis unit 13 sets the calculated approximation formula F _vc as the current approximation formula FC _vc in the deterioration state determination mode. The initial state determination mode is a mode for determining the state of the smoothing capacitor 42 when the power supply device 4 is in the initial state. The deterioration state determination mode is a mode for determining the deterioration state of the smoothing capacitor 42 .

The diagnosis unit 13 can determine the deterioration and life of the smoothing capacitor 42 based on the calculated initial approximation formula FB _vc and current approximation formula FC _vc . It shows that the capacitance of the smoothing capacitor 42 decreases as the difference or ratio between the initial approximation formula FB _vc and the current approximation formula FC _vc changes. The diagnosis unit 13 can detect a decrease in the capacitance of the smoothing capacitor 42 by calculating the difference or ratio between the initial approximation formula FB _vc and the current approximation formula FC _vc .

For example, the diagnosis unit 13 sets the average value of the current moving average peak values _Irp included in the initial approximation formula _FBvc as the initial value of the current characteristic value _Ic , and the current moving average peak value Irp included in the current approximation formula _FCvc . The average value of _rp is calculated as the current value of the current characteristic value _Ic . The diagnosis unit 13 can calculate the difference or ratio between the initial value and the current value of the current characteristic value _Ic as the difference or ratio between the initial approximation formula _FBvc and the current approximation formula _FCvc . Hereinafter, the average value of the current moving average peak values _Irp is referred to as the current moving average peak value average value _Irpav .

10 is a diagram showing an example of a relationship between a current moving average peak value average value and a capacitance of a smoothing capacitor according to Embodiment 1. FIG. As shown in FIG. 10, current moving average peak value average value _Irpav decreases as the capacitance of smoothing capacitor 42 decreases.

FIG. 11 is a diagram showing an example of the relationship between the current moving average peak value average value, the resistance value of the inrush current limiting resistor, and the capacitance of the smoothing capacitor according to the first embodiment. FIG. 11 shows an example in which the rectifier circuit 41 is a full-wave rectifier circuit and the effective value of the AC voltage of the AC power supply 2 is 100V. As shown in FIG. 11, the current moving average peak value average value I _rpav differs depending on the resistance value of the inrush current limiting resistor 43 and the capacitance of the smoothing capacitor 42 .

The diagnosis unit 13 can also calculate the initial value of the current characteristic value _Ic using a calculation formula or a table obtained from the equivalent circuit of the power supply device 4 or the like. For example, the diagnosis unit 13 receives from an input unit (not shown) the effective value and frequency of the AC voltage of the AC power supply 2, the type of the rectifier circuit 41, the resistance value of the inrush current limiting resistor 43, and the capacitance of the smoothing capacitor 42. Get information. The diagnosis unit 13 can calculate the initial value of the current characteristic value _Ic based on the acquired information. The types of the rectifier circuit 41 include full-wave rectification and half-wave rectification.

Returning to FIG. 3, the description of the diagnosis unit 13 is continued. As shown in FIG. 3, the diagnosis unit 13 includes a calculation unit 21, a storage unit 22 that stores information on the initial characteristics calculated by the calculation unit 21, and a current characteristic value _Ic calculated by the calculation unit 21. A judgment unit 23 is provided for judging deterioration and life of the smoothing capacitor 42 based on the value and the initial value of the current characteristic value _Ic stored in the storage unit 22 . The initial characteristic information stored in the storage unit 22 is, for example, the initial value of the current characteristic value _Ic and the initial approximation formula _FBvc . Note that, hereinafter, the initial value of the current characteristic value _Ic may be referred to as the initial characteristic value _Iic , and the current value of the current characteristic value _Ic may be referred to as the current characteristic value _Icc .

Calculation unit 21 calculates voltage phase θon based on voltage instantaneous _{value vd} obtained from voltage measurement unit 12, and voltage phase calculation unit 31 calculates voltage phase θon based on current instantaneous value _id obtained from current measurement unit 11. , and a current characteristic calculator 32 for calculating the current characteristic value _Ic .

The voltage phase calculation unit 31, for example, repeatedly calculates the voltage phase based on the voltage instantaneous value _vd measured by the voltage measurement unit 12, and calculates the voltage phase at the timing when the ON signal indicated by the electrical equipment 3 is output. It can be calculated as the phase θ _on . The voltage phase calculator 31 can also calculate the voltage phase at the timing when the ON signal is output from the AC power supply 2 as the voltage phase _θon .

12 is a diagram illustrating a configuration example of a current characteristic calculation unit according to the first embodiment; FIG. As shown in FIG. 12, the current characteristic calculator 32 includes a square value calculator 51, a period integrated value calculator 52, a period average value calculator 53, a square root value calculator 54, and a peak value determiner 55. , a peak average value calculator 56 and a current characteristic output unit 57 .

The squared value calculator 51 acquires the current instantaneous value _id measured by the current measuring unit 11 at a preset cycle. The squared value calculator 51 repeatedly squares the instantaneous current ^value _id every time the instantaneous current value _id is obtained, thereby calculating the squared value _id2 . The squared value calculator 51 outputs the calculated squared value i _d ² to the period integrated value calculator 52 every time it calculates the squared value i _d ² .

Every time the period integrated value calculation unit 52 acquires the squared value _id ² from the squared value calculation unit 51, the period integrated value calculation unit 52 integrates the squared value _id ² from the current time point to the preset period T before, thereby obtaining the period integrated value I Iteratively calculate _da . The period integrated value calculator 52 outputs the calculated period integrated value _Ida to the period average value calculator 53 each time it calculates the period integrated value _Ida .

The period average value calculation unit 53 divides the period integration value _Ida by a preset period T each time it acquires the period integration value _Ida from the period integration value calculation unit 52, thereby repeating the period average value _Idav . calculate. The period average value calculator 53 outputs the calculated period average value I _dav to the square root value calculator 54 each time it calculates the period average value I _dav .

Each time the square root value calculator 54 acquires the period average value I _dav from the period average value calculator 53 , the square root value calculator 54 calculates the current moving average value I _r that is the square root of the period average value I _dav . The square root value calculation unit 54 outputs the calculated current moving average value _Ir to the peak value determination unit 55 each time it calculates the current moving average value _Ir .

The peak value determination unit 55 determines the current moving average repeatedly output from the square root value calculation unit 54 from the timing when the ON signal indicating the power-on timing is acquired from the electrical equipment 3 until the preset period TA elapses. A current moving average value I _r that is the largest among the values I _r is determined. The peak value determination unit 55 determines that the current moving average value _Ir determined to be the largest is the current moving average peak value _Irp . The period TA is longer than the preset period T, and is, for example, twice as long as the preset period T or more.

Hereinafter, the period integration value I _da , period average value I _dav , current moving average value I _r , or current moving average peak value I _rp described above will be referred to as current characteristic value I _c1 . The period average value I _dav , current moving average value I _r , or current moving average peak value I _rp are examples of values based on the period integrated value I _da . Also, the average value of the current moving average peak values _Irp may be referred to as the current characteristic value _Ic2 . Note that when the current characteristic value _Ic1 and the current characteristic value _Ic2 are not distinguished from each other, they may be referred to as the current characteristic value _Ic .

The peak average value calculator 56 acquires the current characteristic value I _c1 and also acquires the voltage phase θ _on calculated by the voltage phase calculator 31 . The peak average value calculator 56 calculates the above-described approximate expression _Fvc based on the acquired current characteristic value _Ic1 and the voltage phase _θon .

For example, in the initial state determination mode, the peak average value calculator 56 calculates an initial approximation formula FB _vc and stores information on the calculated initial approximation formula FB _vc in the storage unit 22 . Further, the peak average value calculation unit 56 calculates the current moving average peak value average value _Irpav , which is the current characteristic value _Ic2 , as the initial characteristic value _Iic based on the calculated initial approximation formula _FBvc .

In addition, in the deterioration state determination mode, the peak average value calculation unit 56 calculates the current approximate expression FC _vc of the smoothing capacitor 42, and based on the calculated current approximate expression FC _vc , the current characteristic value I _c2 is calculated. The moving average peak value average value _Irpav is calculated as the current characteristic value _Icc .

Note that, in the deterioration state determination mode, the calculation unit 21 replaces the approximate expression representing the relationship between the current moving average peak value _Irp and the voltage phase θon _with the period integrated value I _da , the period average value I _dav , Alternatively, an approximation expression representing the relationship between the current moving average value _Ir and the voltage phase _θon can be calculated as the initial approximation expression _FBvc .

The current characteristic output unit 57 also stores the initial approximate expression FB _vc and the initial characteristic value I _ic calculated in the current characteristic calculation unit 32 in the storage unit 22 . The current characteristic output unit 57 also outputs the current characteristic value _Icc calculated by the current characteristic calculation unit 32 to the determination unit 23 . The current characteristic output unit 57 can also output the current characteristic value _Ic1 calculated by the current characteristic calculation unit 32 in the deterioration state determination mode to the determination unit 23 as the current characteristic value _Icc .

Next, the determination unit 23 will be described. 13 is a diagram illustrating a configuration example of a determination unit according to the first embodiment; FIG. As shown in FIG. 13, the determination unit 23 determines the deterioration and life of the smoothing capacitor 42 in the deterioration state determination mode. The determination unit 23 includes a comparison unit 61 , a deterioration degree determination unit 62 and a life determination unit 63 .

The comparison unit 61 compares the initial characteristic value I _ic obtained from the storage unit 22 and the current characteristic value I _cc obtained from the current characteristic calculation unit 32 . For example, the comparison unit 61 calculates the amount of decrease, which is the difference between the initial characteristic value _Iic and the current characteristic value _Icc . The comparison unit 61 can also calculate a reduction rate, which is the ratio of the current characteristic value _Icc to the initial characteristic value _Iic .

Further, the comparison unit 61 can use the current characteristic value _Ic1 instead of the current characteristic value _Ic2 as the current characteristic value _Icc to be compared with the initial characteristic value _Iic . The current characteristic value I _c1 is, for example, the period average value I _dav , the current moving average value I _r , the current moving average peak value I _rp , or the current moving average peak value I _rp , as described above.

In this case, the comparison unit 61 corresponds to the voltage phase _θon calculated by the voltage phase calculation unit 31 in the deterioration state determination mode among the current characteristic values _Ic1 at each voltage phase _θon included in the initial approximation formula _FBvc. The current characteristic value I _c1 is set to the initial characteristic value I _ic . For example, assume that the voltage phase θ _on calculated by the voltage phase calculator 31 is 90 degrees. In this case, the comparison unit 61 sets the current characteristic value I _c1 obtained by substituting 90 degrees as the voltage phase θ _on into the initial approximation formula FB _vc as the initial characteristic value I _ic . In addition, in the deterioration state determination mode, the comparison unit 61 sets the current characteristic value _Ic1 calculated by the calculation unit 21 as the current characteristic value _Icc . Then, the comparison unit 61 can calculate the ratio or difference between the initial characteristic value _Iic and the current characteristic value _Icc .

The deterioration degree determination unit 62 can determine the deterioration degree of the smoothing capacitor 42 based on the comparison result by the comparison unit 61 . Specifically, the deterioration degree determination unit 62 has deterioration degree determination information in which a deterioration degree is associated with each ratio or difference between the initial characteristic value _Iic and the current characteristic value _Icc . Such deterioration degree determination information is, for example, information of a table or an arithmetic expression.

The deterioration degree determination unit 62 determines the degree of deterioration corresponding to the amount of decrease or the rate of decrease as the degree of deterioration of the smoothing capacitor 42 based on the degree of deterioration determination information and the amount of decrease or the rate of decrease calculated by the comparison unit 61. be able to.

The life determination unit 63 can determine the life of the smoothing capacitor 42 based on the comparison result by the comparison unit 61 . Specifically, the lifespan determination unit 63 has lifespan determination information that associates the remaining time until the lifespan with each ratio or difference between the initial characteristic value _Iic and the current characteristic value _Icc . Such life determination information is, for example, information of a table or an arithmetic expression.

Based on the life determination information and the reduction amount or reduction rate calculated by the comparison section 61, the life determination section 63 can determine the remaining period corresponding to the reduction amount or reduction rate as the life of the smoothing capacitor 42. can.

Next, the operation of the diagnosis unit 13 of the condition diagnosis device 1 will be explained using a flowchart. 14 is a flowchart illustrating an example of processing by a diagnosis unit of the condition diagnosis device according to the first embodiment; FIG.

As shown in FIG. 14, the diagnosis unit 13 of the condition diagnosis device 1 determines whether or not the set mode is the initial condition determination mode (step S11). Such an initial state determination mode is set by, for example, an input operation to an input unit (not shown) in the state diagnostic device 1 .

When the diagnostic unit 13 determines that the set mode is the initial state determination mode (step S11: Yes), it determines whether or not it is within a set period from the power-on timing (step S12). When the diagnosis unit 13 determines that it is within the set period from the power-on timing (step S12: Yes), the diagnosis unit 13 executes initial characteristic calculation processing (step S13). Such initial characteristic calculation processing is, for example, the processing of steps S21 to S26 shown in FIG. 15, and will be described later.

If the diagnosis unit 13 determines that the set mode is not the initial state determination mode (step S11: No), or determines that it is not within the set period from the power-on timing (step S12: No), or step S13 When the process of (1) is completed, it is determined whether or not the set mode is the deterioration state determination mode (step S14). Such a deterioration state determination mode is set by, for example, an input operation to an input unit (not shown) in the state diagnosis device 1 .

When the diagnostic unit 13 determines that the set mode is the deterioration state determination mode (step S14: Yes), it determines whether or not it is within a set period from the power-on timing (step S15). When the diagnostic unit 13 determines that the set period has elapsed since the power-on timing (step S15: Yes), it executes deterioration life determination processing (step S16). Such deterioration life determination processing is, for example, the processing of steps S31 to S35 shown in FIG. 16, and will be described later.

If the diagnosis unit 13 determines that the set mode is not the deterioration state determination mode (step S14: No), or determines that it is not within the set period from the power-on timing (step S15: No), or step S16 When the processing of is completed, the processing shown in FIG. 14 is terminated.

Next, the initial characteristic calculation process in step S13 shown in FIG. 14 will be described. 15 is a flowchart illustrating an example of initial characteristic calculation processing according to the first embodiment; FIG.

As shown in FIG. 15, the diagnosis unit 13 calculates a voltage phase _θon , which is the voltage phase at power-on timing (step S21), and calculates a current characteristic value _Ic1 (step S22). Then, the diagnosis unit 13 determines whether or not it is time to calculate the current characteristic value _Ic2 (step S23). In step S23, for example, in the initial state determination mode, the diagnosis unit 13 calculates the current characteristic value _Ic2 when the calculation of the voltage phase _θon and the current characteristic value _Ic1 is performed a preset number of times or for a period of time. It can be determined that it is time.

When the diagnosis unit ₁₃ determines that it is time to calculate the current characteristic value _Ic2 (step S23: Yes) _, the approximation formula _Fvc is calculated (step S24). _In addition, _the diagnosis unit 13 calculates the initial characteristic value I _ic based on the approximate expression F _vc (step S25). (step S26). When the diagnostic unit 13 determines that it is not the timing for calculating the current characteristic value _Ic2 (step S23: No), or when the process of step S26 ends, the process shown in FIG. 15 ends.

Next, the deterioration life determination process in step S16 shown in FIG. 14 will be described. 16 is a flowchart illustrating an example of deterioration life determination processing according to the first embodiment; FIG.

As shown in FIG. 16, the diagnostic unit 13 calculates a voltage phase _θon , which is the voltage phase at power-on timing (step S31), and calculates a current characteristic value _Ic1 (step S32). Then, the diagnosis unit 13 determines whether or not it is time to calculate the current characteristic value _Ic2 (step S33). In step S33, the diagnostic unit 13 calculates the current characteristic value Ic2 _, for example, when the calculation of the voltage phase _θon and the current characteristic value _Ic1 is performed a preset number of times or for a period of time in the deterioration state determination mode. It can be determined that it is time.

When the diagnosis unit 13 _determines that it is time to calculate the current characteristic value _Ic2 (step S33: Yes), the current _{characteristic} A current characteristic value _Ic2 is calculated as the value _Icc (step S34). In step S34, the diagnosis unit 13 calculates the current approximate expression FC vc based on the voltage phase θ _on and the current characteristic value I _c1 calculated in steps S31 and S32, and the current approximate expression FC _vc is calculated from the current approximate expression FC _vc . A characteristic value _Ic2 can be calculated.

Diagnosis unit 13 determines deterioration and life of smoothing capacitor 42 based on the result of comparison between calculated current characteristic value _Icc and initial characteristic value _Iic stored in storage unit 22 (step S35). If the diagnostic unit 13 determines that it is not the time to calculate the current characteristic value _Ic2 (step S33: No), or if the process of step S35 ends, the process shown in FIG. 16 ends.

The deterioration life determination process in step S16 shown in FIG. 14 is not limited to the example shown in FIG. 17 is a flowchart illustrating another example of the deterioration life determination process according to the first embodiment; FIG.

As shown in FIG. 17, the diagnostic unit 13 calculates a voltage phase _θon , which is the voltage phase at power-on timing (step S41), and calculates a current characteristic value _Ic as the current characteristic value _Icc (step S42). ). Then, the diagnosis unit 13 determines deterioration and life of the smoothing capacitor 42 based on the voltage phase _θon calculated in step S41 and the current characteristic value _Ic calculated in step S42 (step S43).

For example, the diagnosis unit 13 stores the current characteristic value I _c obtained by substituting the voltage phase θ _on calculated in step S41 into the initial approximation formula FB _vc stored in the storage unit 22, and the current characteristic value I c calculated in step S42. Compare with _c . The diagnosis unit 13 can determine the deterioration and life of the smoothing capacitor 42 based on the comparison result. Diagnosis part 13 ends the processing shown in Drawing 17, when processing of Step S43 is completed.

18 is a diagram illustrating an example of a hardware configuration of a diagnosis unit in the condition diagnosis device according to Embodiment 1; FIG. As shown in FIG. 18 , diagnosis unit 13 of condition diagnosis device 1 includes a computer having processor 101 , memory 102 , and interface circuit 103 .

Processor 101 , memory 102 and interface circuit 103 can transmit and receive data to and from each other via bus 104 . Storage unit 22 is implemented by memory 202 . The processor 101 reads out and executes programs stored in the memory 102 to perform the functions of the calculation unit 21 , the storage unit 22 , and the determination unit 23 . The processor 101 is an example of a processing circuit and includes one or more of a CPU (Central Processing Unit), a DSP (Digital Signal Processor), and a system LSI (Large Scale Integration).

The memory 102 includes one or more of RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Registered Trademark) (Electrically Erasable Programmable Read Only Memory). include. The memory 102 also includes a recording medium in which a computer-readable program is recorded. Such recording media include one or more of nonvolatile or volatile semiconductor memories, magnetic disks, flexible memories, optical disks, compact disks, and DVDs (Digital Versatile Disks). The diagnosis unit 13 of the condition diagnosis device 1 may include integrated circuits such as ASIC (Application Specific Integrated Circuit) and FPGA (Field Programmable Gate Array).

In the example described above, the diagnosis unit 13 determines the voltage phase at the power-on timing based on the ON signal from the AC power supply 2 or the electrical equipment 3, but the present invention is not limited to such an example. For example, the diagnostic unit 13 can also determine the voltage phase at the power-on timing without using the ON signal from the AC power supply 2 or the electrical equipment 3 . For example, the diagnostic unit 13 can also determine the voltage phase at the power-on timing from the change state of the current instantaneous value _id .

Further, the current characteristic calculator 32 may have the configuration shown in FIG. 12 for each of the initial state determination mode and the deterioration state determination mode. That is, the current characteristic calculator 32 has the configuration shown in FIG. 12 for performing the calculation process in the initial state determination mode and the configuration shown in FIG. 12 for performing the calculation process in the deterioration state determination mode. may

As described above, the condition diagnosis device 1 according to the first embodiment includes the current measurement section 11 and the diagnosis section 13 . Current measurement unit 11 measures current instantaneous value _id , which is the instantaneous value of current between power supply 4 and AC power supply 2 that supplies AC power to power supply 4 having rectifier circuit 41 and smoothing capacitor 42 . Diagnosis unit 13 detects deterioration and life of smoothing capacitor 42 based on period integration value _Ida , which is a value obtained by squaring current instantaneous value _id measured by current measurement unit 11 and integrating it for a preset period of time. Diagnose at least one of them. As a result, deterioration and service life of the smoothing capacitor 42 can be diagnosed from the outside of the power supply device 4 having the rectifying circuit 41 and the smoothing capacitor 42 .

The diagnosis unit 13 also includes a calculation unit 21 and a determination unit 23 . The calculator 21 calculates the period integrated value _Ida or a value based on the period integrated value _Ida as the current characteristic value _Ic . The determining unit 23 determines the deterioration and life of the smoothing capacitor 42 based on the result of comparison between the current characteristic value _Ic and the initial characteristic value _Iic of the smoothing capacitor 42 . This makes it possible to easily diagnose the deterioration and life of the smoothing capacitor 42 .

The calculator 21 also calculates a voltage phase _{θ on} that is the voltage phase of the AC power supply 2 at the timing when the supply of AC power from the AC power supply 2 to the rectifier circuit 41 is started. The determination unit 23 compares the initial characteristic value _Iic corresponding to the voltage phase _θon calculated by the voltage phase calculation unit 31 and the current characteristic value _Ic , which is the current characteristic value _Icc , to the smoothing capacitor 42. Determining deterioration and life. This makes it possible to easily diagnose the deterioration and life of the smoothing capacitor 42 even when the power-on timing is not at the same voltage phase _θon .

Further, the calculation unit 21 calculates an average value of the current characteristic values I _c based on the current characteristic values I _c and the voltage phase _θ on calculated by the voltage phase calculation unit 31 . Determination unit 23 determines the deterioration and life of smoothing capacitor 42 based on the difference or ratio between the average current characteristic value _Ic , which is the current characteristic value _Icc , and the initial characteristic value _Iic . This makes it possible to accurately diagnose the deterioration and life of the smoothing capacitor 42 .

Further, the calculator 21 calculates an initial characteristic value I _ic based on the current characteristic value I _c and the voltage phase _θ on calculated by the voltage phase calculator 31 . As a result, even if the power supply device 4 has individual differences, it is possible to accurately diagnose the deterioration and life of the smoothing capacitor 42 .

Further, the calculation unit 21 repeatedly calculates the period integrated value _Ida at intervals shorter than the preset period T, and calculates the peak value of the period integrated value _Ida , the peak value of the value based on the period integrated value _Ida , or The average value of the peak values is calculated as the current characteristic value _Ic . This makes it possible to accurately diagnose the deterioration and life of the smoothing capacitor 42 .

The configuration shown in the above embodiment shows an example of the content of the present invention, and it is possible to combine it with another known technology, and one configuration can be used without departing from the scope of the present invention. It is also possible to omit or change the part.

1 state diagnosis device 2 AC power supply 3 electrical equipment 4 power supply device 5 load 6 switch 10 current transformer 11 current measurement unit 12 voltage measurement unit 13 diagnosis unit 21 calculation unit 22 storage unit , 23 determination unit, 31 voltage phase calculation unit, 32 current characteristic calculation unit, 41 rectifier circuit, 42 smoothing capacitor, 43 rush current limiting resistor, 44 switch, 51 square value calculation unit, 52 period integrated value calculation unit, 53 period average Value calculation unit 54 Square root value calculation unit 55 Peak value determination unit 56 Peak average value calculation unit 61 Comparison unit 62 Deterioration degree determination unit 63 Life determination unit.

Claims (7)

a current measurement unit that measures an instantaneous value of current between an AC power supply that supplies AC power to a power supply device that includes a rectifying circuit and a smoothing capacitor, and the power supply device;
a voltage phase calculator that calculates the voltage phase of the AC power supply at a first timing, which is the timing at which supply of AC power from the AC power supply to the rectifier circuit is started;
A current moving average value, which is a moving average value of magnitudes of the instantaneous values measured by the current measuring unit during a first period from the first timing, is calculated for a second period longer than the first period. and calculating a current moving average peak value, which is a peak value of the current moving average value in the second period, a plurality of times when determining the deterioration state of the smoothing capacitor, Acquiring a first relationship that is a relationship between a first voltage phase that is a voltage phase and a first current moving average peak value that is the current moving average peak value at the time of determining the deterioration state of the smoothing capacitor, and obtaining a first relationship in the first relationship a diagnostic unit that diagnoses at least one of deterioration and life of the smoothing capacitor based on the overall decrease in the first current moving average peak value over time . The diagnosis unit
a second relationship that is a relationship between a second voltage phase that is the voltage phase in the initial state of the power supply and a second moving average peak value that is the current moving average peak value in the initial state of the power supply; Determine at least one of deterioration and life of the smoothing capacitor obtained in advance and based on a comparison between the first relationship and the second relationship
The condition diagnosis device according to claim 1, characterized in that: The diagnosis unit
Calculate a first current moving average peak value average value that is an average value of the first current moving average peak values included in the first relationship, and average the second current moving average peak values included in the second relationship A second current moving average peak value average value is calculated, and based on a comparison between the first current moving average peak value average value and the second current moving average peak value average value, deterioration of the smoothing capacitor and 3. The condition diagnosis device according to claim 2, wherein at least one of lifespans is determined. 4. The condition diagnosis device according to claim 2, wherein said first relationship and said second relationship are approximate expressions . The moving average value is obtained by dividing a period integrated value, which is a value obtained by accumulating a value obtained by squaring the instantaneous value during the first period, by the first period, and obtaining the square root of the division result. The condition diagnosis device according to any one of claims 1 to 4 . a current measuring step of measuring an instantaneous value of a current between an AC power supply that supplies AC power to a power supply comprising a rectifying circuit and a smoothing capacitor and the power supply;
A voltage phase calculation step of calculating the voltage phase of the AC power supply at a first timing, which is the timing at which the supply of AC power from the AC power supply to the rectifier circuit is started;
A current moving average value, which is a moving average value of magnitudes of the instantaneous values measured in the current measuring step from the first timing to the first period, is calculated for a second period longer than the first period. and calculating a current moving average peak value, which is a peak value of the current moving average value in the second period, a plurality of times when determining the deterioration state of the smoothing capacitor, Acquiring a first relationship that is a relationship between a first voltage phase that is a voltage phase and a first current moving average peak value that is the current moving average peak value at the time of determining the deterioration state of the smoothing capacitor, and obtaining a first relationship in the first relationship and a diagnostic step of diagnosing at least one of deterioration and life of the smoothing capacitor based on an overall decrease in the first current moving average peak value over time . a current measuring step of measuring an instantaneous value of a current between an AC power supply that supplies AC power to a power supply comprising a rectifying circuit and a smoothing capacitor and the power supply;
A voltage phase calculation step of calculating the voltage phase of the AC power supply at a first timing, which is the timing at which the supply of AC power from the AC power supply to the rectifier circuit is started;
A current moving average value, which is a moving average value of magnitudes of the instantaneous values measured in the current measuring step from the first timing to the first period, is calculated for a second period longer than the first period. and calculating a current moving average peak value, which is a peak value of the current moving average value in the second period, a plurality of times when determining the deterioration state of the smoothing capacitor, Acquiring a first relationship that is a relationship between a first voltage phase that is a voltage phase and a first current moving average peak value that is the current moving average peak value at the time of determining the deterioration state of the smoothing capacitor, and obtaining a first relationship in the first relationship a diagnostic step of diagnosing at least one of deterioration and life of the smoothing capacitor based on the overall decrease in the first current moving average peak value over time. program.

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