JP2000308339A - Switching power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a switching power unit which can prevent the occurrence of an unexpected cessation of operation and can prevent the occurrence of trouble in a load by accurately predicting the service life of an electrolytic capacitor. SOLUTION: A switching power unit generates a DC voltage by rectifying and smoothing an AC input and an output voltage Vout by switching, transforming, rectifying, and smoothing the DC voltage and is provided with an electrolytic capacitor C1. The power unit is loaded with a processing program containing a step of measuring the frequency (f) of the AC input, a step of measuring the output voltage Vout an an output current Iout, and a step of measuring a terminal voltage VCP of the capacitor C1. The program also includes a step of converting the measured terminal voltage VCP into a terminal voltage, when the load is a rated one and a step of comparing the converted terminal voltage with the preset initial value of the terminal voltage VCP, and when the compared value becomes a prescribed value or smaller, sending an abnormality informing signal to the outside by discriminating that the capacitance of the capacitor C1 has dropped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply, and more particularly, to a switching power supply capable of determining the life of the capacitance of a smoothing electrolytic capacitor.

[0002]

2. Description of the Related Art In general, in a switching power supply, an AC input is rectified and smoothed using a rectifying element and an electrolytic capacitor to obtain a DC voltage, and the obtained DC voltage is pulse-controlled by pulse width modulation control of the switching element. Supply to the primary side of the transformer as a state voltage, and the transformed AC output induced on the secondary side of the transformer is further rectified and smoothed into a DC constant voltage output, and this DC constant voltage output is used for various electric devices,
We supply them to electronic devices.

[0003]

In the case of the above-mentioned conventional switching power supply, the DC constant voltage output is controlled to be constant by pulse width modulation (PWM) control, and the switching is performed by detecting an abnormality of the DC constant voltage output. Functions such as stopping the operation of the power supply device are realized using a microcomputer.

However, in the prior art, stabilization of DC constant voltage output and abnormality detection are performed, but in reality, the life of a smoothing electrolytic capacitor is not predicted.

Therefore, even if an abnormality occurs in the DC constant voltage output due to a decrease in the capacitance of the electrolytic capacitor with time, the operation of the switching power supply is stopped as an abnormality of the output voltage. That situation occurs.

Further, when the DC constant voltage output becomes higher due to the decrease in the capacitance of the electrolytic capacitor, the electronic equipment or the like connected as the load of the switching power supply unit malfunctions, which causes an extreme malfunction. In such a case, there is a possibility that an operation program or data mounted on the electronic device or the like may be damaged, which may cause a trouble.

The present invention has been made in view of the above circumstances, and accurately predicts the life of a smoothing electrolytic capacitor to prevent an unexpected operation stop of a switching power supply.
Still another object of the present invention is to provide a switching power supply device capable of preventing a trouble caused by an abnormal supply voltage to a load.

[0008]

According to the first aspect of the present invention,
The AC input is rectified and smoothed into a DC voltage, and the DC voltage is subjected to a switching process, a transforming process, a rectifying and smoothing process to an output voltage, and a switching power supply device having an electrolytic capacitor for smoothing process. Measuring the output voltage and output current, measuring the terminal voltage of the electrolytic capacitor, and measuring the frequency, output voltage and output current, and the terminal voltage of the electrolytic capacitor. Equipped with a processing program that converts the terminal voltage into the terminal voltage at the rated load, and compares the converted terminal voltage with a preset terminal voltage to determine a decrease in the capacitance of the electrolytic capacitor. It is characterized by having done.

According to the present invention, the frequency of the AC input, the measurement of the output voltage and the output current, the measurement of the terminal voltage of the electrolytic capacitor, the measured frequency, the output voltage and the output current, and the Conversion of this terminal voltage to the terminal voltage at the rated load based on the terminal voltage of the capacitor, and determination of the decrease in the capacitance of the electrolytic capacitor by comparing the converted terminal voltage with a preset terminal voltage initial value Can be automatically performed, thereby accurately predicting the life of the electrolytic capacitor for smoothing, and preventing the switching power supply from unexpectedly stopping operation.

According to a second aspect of the present invention, an AC input is rectified and smoothed using a rectifying element and an electrolytic capacitor to obtain a DC voltage, and the obtained DC voltage is pulse-shaped by a switching control of a switching element by a control unit. A switching power supply that supplies a voltage as a voltage to the primary side of the transformer and rectifies and smoothes the transformed AC output induced on the secondary side of the transformer to produce an output voltage; The process of measuring the voltage and output current, the process of measuring the terminal voltage of the electrolytic capacitor, and the terminal voltage at the rated load based on the measured frequency, output voltage and output current, and the terminal voltage of the electrolytic capacitor. In the process of conversion, and comparing the converted terminal voltage with the preset initial value of the terminal voltage, if the comparison value is equal to or less than a predetermined value, the electrolytic capacitor The processing program including the steps of delivering a decreased judgment abnormality notification signal of the electrostatic capacitance to the outside is characterized in that mounted on the control unit.

According to the present invention, in addition to the effect of the first aspect of the present invention, an abnormality notification signal can be sent to the outside when it is determined that the capacitance of the electrolytic capacitor has decreased. In addition, it is possible to prevent the occurrence of the trouble as described in the conventional example due to the abnormal supply voltage to the load of the switching power supply device.

According to a third aspect of the present invention, in the switching power supply device according to the first or second aspect, the step of converting the terminal voltage of the electrolytic capacitor into a terminal voltage at the time of rated load is performed.
The measurement is performed using a difference between the maximum value and the minimum value of the measured terminal voltage of the electrolytic capacitor and a difference between the maximum value and the minimum value of the terminal voltage at the time of rated load.

According to the present invention, when the measured terminal voltage of the electrolytic capacitor is converted into the terminal voltage at the rated load, the difference between the maximum value and the minimum value of the measured terminal voltage of the electrolytic capacitor and the rated Since the difference between the maximum value and the minimum value of the terminal voltage is used, the conversion into the terminal voltage at the time of the rated load and the determination of the decrease in the capacitance can be performed with higher accuracy.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A switching power supply according to an embodiment of the present invention will be described below.

In this switching power supply device, as shown in FIG. 1, an AC input from an AC power supply 1 is full-wave rectified by a diode bridge circuit 2 in which diodes serving as rectifiers are bridge-connected, and an electrolytic capacitor C1 is used. After obtaining the DC voltage by smoothing, the obtained DC voltage is
By switching control of the switching element S by 0 (for example, pulse width modulation control), a pulsed voltage is supplied to the primary side of the transformer T, and the transformed AC output induced on the secondary side of the transformer T is used by diodes D1 and D2. The output current Iout is supplied to the electronic device 20 as a load as an output voltage Vout by rectification and smoothing using the choke coil L and the electrolytic capacitor C2.

The control unit 10 measures the frequency f of the AC input, the process of measuring the output voltage Vout and the output current Iout, and the process of measuring the terminal voltage VCP of the electrolytic capacitor C1. Frequency F, output voltage Vout and output current Iout, electrolytic capacitor C1
The process of converting this terminal voltage VCP to the terminal voltage at the rated load based on the terminal voltage VCP of the above, and comparing the converted terminal voltage with the preset initial value Vini of the terminal voltage at the rated load,
When the comparison value is equal to or less than a predetermined value, the electrolytic capacitor C
(1) a processing program including a step of determining that the capacitance has decreased and transmitting an abnormality notification signal to the outside.

The processing program further includes a program for performing initialization processing of processing data and a timer function.

The initial value Vini of the terminal voltage of the electrolytic capacitor C1 is stored in a memory (ROM) 11 in advance.

The control unit 10 includes an A / D conversion unit 1
2, the frequency f of the AC input, the output voltage Vout and the output current Iout, and the terminal voltage VCP of the electrolytic capacitor C1.
Each data is taken in.

The switching power supply shown in FIG.
Although the diode bridge circuit 2 is provided for rectification of the AC input from the AC power supply 1, a choke for boosting the power factor or a boost regulator can be used instead. In this case, only the threshold value of the capacitor voltage VCP changes.

Next, the details of the process of determining the capacitance of the electrolytic capacitor C1 in the switching power supply device according to the above-described processing program will be described with reference to FIGS.

First, after a power switch (not shown) is turned on (step S1), the processing program temporarily initializes processing data (maximum and minimum values of the terminal voltage VCP, the number of determinations n) (step S2).

Next, the processing program determines the output voltage Vout.
(Step S3) and the output current Iout (Step S4). Then, the product of the output voltage Vout and the output current Iout is stored as the power W (step S5). If there are a plurality of output terminals, the total is calculated.

Next, the processing program determines whether or not the value of the power W is equal to or greater than a predetermined value (for example, 150) (step S6). This is because accurate values cannot be obtained if the load is extremely small relative to the rating. The certain value set in advance varies depending on the rated load of the switching power supply device.

Here, the processing program terminates the processing unless the value of the power W is equal to or more than a predetermined value.

If the value of the power W is equal to or greater than a predetermined value, the frequency f of the AC input from the AC power supply 1 is measured (step S7).

Next, the measurement time t = 0 by the timer function.
(Step S8), the capacitor terminal voltage VCP is measured (step S9), the maximum value during this period is VCPmax (steps S10 and S11), and the minimum value is VCPmin (steps S12 and S13).

In the case of the full-wave rectification method of the present embodiment, such a process is repeated for a period of half the period of the AC input (1 / 2f) (step S14).

Next, the processing program executes the maximum value Vcpmax and the minimum value Vcpm of the terminal voltage VCP in order to improve the accuracy.
Then, a difference ΔV from “in” is obtained (step S15).

Then, this value is compared with a value Vini previously set and stored in the memory 11 (step S16), and a comparison value A is obtained.

In this case, since the processing program sets Vini to a value at a rated load and a frequency of 50 Hz, the difference ΔV is set to (ΔV · WO · 50) / (V
Ini · W · f) is converted to the value at the rated load. Where WO is the rated load power.

The value Vini is the value of the initial electrolytic capacitor C
1 is set in advance as the difference between the minimum value and the maximum value of the terminal voltage based on the value of the capacitance at the time of the rated load, and stored in the memory 11. This value Vini also changes depending on the rectification method of the AC input (full-wave rectification, half-wave rectification, presence / absence of a booster circuit) and the like.

Next, the processing program determines whether the comparison value A is equal to or smaller than a preset value (0.6 in this embodiment) (step S17), and the comparison value A is set in advance. If the value is larger than the calculated value, it is determined that there is no decrease in the capacitance, and the process ends.

When the comparison value A becomes 0.6 or less for 10 consecutive times (steps S18 and S19), the processing program sets the capacitance of the electrolytic capacitor C1 to a value less than the allowable value. It is determined that it has decreased.

Then, the processing program sends an abnormality notification signal from the switching power supply to the electronic device 20 to which the output voltage Vout is supplied (step S20), and ends the processing.

If the comparison value A does not become 0.6 or less up to 10 times in succession, the number of determinations n is incremented, and the flow returns to step S3 to repeat the above operation.

In this manner, by the processing of the processing program installed in the switching power supply unit, a decrease in the capacitance of the electrolytic capacitor C1 can be determined, whereby the life of the electrolytic capacitor C1 for smoothing can be accurately predicted. In addition, it is possible to prevent an unexpected operation stop of the switching power supply device.

The electronic device 20 that has received the abnormality notification signal
It is possible to take measures such as saving the operation program and the processing data on the side, and it is possible to prevent the occurrence of trouble due to the abnormal supply voltage.

Incidentally, the latter-stage electrolytic capacitor C2 shown in FIG.
Also, it is of course possible to perform the capacitance determination processing according to the processing program described above.

The present invention is applied to a system in which a plurality of switching power supply units are made redundant, and it is possible to display any one of the power supply units in which an abnormality is detected, thereby interrupting the operation of the entire system. Without doing so, it is possible to take measures such as replacing the power supply in which the abnormality is detected with a new power supply.

[0041]

According to the present invention, it is possible to provide a switching power supply capable of accurately predicting the life of an electrolytic capacitor and preventing an unexpected stop of operation.

Further, according to the present invention, it is possible to provide a switching power supply device capable of avoiding a trouble caused by an abnormal supply voltage to a load caused by a decrease in capacitance of an electrolytic capacitor.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a switching power supply according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing flow according to a processing program installed in the switching power supply according to the embodiment of the present invention.

FIG. 3 is a flowchart showing a flow of processing by a processing program installed in the switching power supply according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Diode bridge circuit 10 Control part 11 Memory 12 A / D conversion part 20 Electronic equipment C1 Electrolytic capacitor Vout Output voltage Iout Output current VCP terminal voltage

Continued on the front page F term (reference) 2G036 AA24 BA37 BB02 CA01 CA06 5G065 BA00 DA06 DA07 EA06 GA06 HA01 JA07 LA01 LA02 LA07 MA01 MA03 MA09 MA10 NA01 NA09 5H006 AA04 AA05 CA00 CA12 CB01 CB03 CC08 DA04 DC02 DC05 FA04 A13A01 CC01 EE08 EE10 FD01 FD11 FD31 FD61 FG01 FG12 XX02 XX13 XX33 XX50

Claims (3)

[Claims] 1. A switching power supply having an electrolytic capacitor for smoothing processing, wherein an alternating current input is rectified and smoothed to obtain a DC voltage, and this DC voltage is subjected to switching processing, voltage transformation processing, rectifying and smoothing to obtain an output voltage, and smoothing processing. In the process of measuring the frequency of the AC input, the process of measuring the output voltage and output current, the process of measuring the terminal voltage of the electrolytic capacitor, the measured frequency, output voltage and output current, terminal voltage of the electrolytic capacitor A process of converting this terminal voltage into a terminal voltage at the time of rated load, and a process of comparing the converted terminal voltage with a preset initial value of the terminal voltage to determine a decrease in the capacitance of the electrolytic capacitor. A switching power supply device comprising a processing program including the same. 2. An AC input is rectified and smoothed using a rectifying element and an electrolytic capacitor to obtain a DC voltage, and the obtained DC voltage is converted into a pulse-like voltage by a switching control of a switching element by a control unit, so that the primary side of the transformer is obtained. A switching power supply that rectifies and smoothes the transformed AC output induced on the secondary side of the transformer to produce an output voltage, wherein the step of measuring the frequency of the AC input and the step of measuring the output voltage and output current The process of measuring the terminal voltage of the electrolytic capacitor, the process of converting this terminal voltage to the terminal voltage at the rated load based on the measured frequency, output voltage and output current, and the terminal voltage of the electrolytic capacitor. If the comparison value is equal to or less than a predetermined value when the measured terminal voltage is compared with the preset initial value of the terminal voltage, it is determined that the capacitance of the electrolytic capacitor has decreased. And abnormality notification signal switching power supply apparatus characterized by a processing program comprising the steps of sending to the outside and mounted on the control unit. 3. The process of converting the terminal voltage of the electrolytic capacitor into a terminal voltage at a rated load includes a step of converting a difference between a maximum value and a minimum value of the measured terminal voltage of the electrolytic capacitor into a maximum value of the terminal voltage at a rated load. 3. The switching power supply device according to claim 1, wherein the switching is performed using a difference between the value and the minimum value.