JP2011109823A - Power supply apparatus and method for determining capacitor life - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply apparatus wherein the life of a capacitor for smoothing the direct current can be determined correctly, and to provide a method for determining the capacitor life. <P>SOLUTION: A detection capacitor 4 is inserted in series between a diode bridge 2 and an electrolytic capacitor 3 so that the terminal voltage of the electrolytic capacitor 3 can be detected, the terminal voltage Vd of the detection capacitor 4 is detected immediately after a DC power supply apparatus PS is introduced and before an inverter circuit 11 is started, the detection result is compared with a reference voltage Vref corresponding to the terminal voltage Vd of the detection capacitor 4 in the early stage of the electrolytic capacitor 3, and a decision is made that the life of the electrolytic capacitor 3 has expired if the terminal voltage Vd is greater than or equal to the reference voltage Vref. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power supply apparatus that outputs a DC voltage by smoothing a DC power supply with a capacitor and a capacitor life determination method.

  Conventionally, as described in Patent Document 1 and Patent Document 2, a method has been devised in which the lifetime is determined by detecting electrical characteristics of a capacitor (mainly an electrolytic capacitor) that smoothes a DC power supply. . That is, Patent Document 1 discloses a technique for determining the life by detecting that the charge / discharge time is shortened compared to the initial time when the capacitance of the capacitor in the lighting device decreases at the end of the life. . Patent Document 2 includes a counter that measures the discharge time of a capacitor, and when the measured discharge time becomes shorter than a reference discharge time, a technique for displaying on the display that the capacitor is time for replacement Is disclosed.

JP 2006-236666 A JP 7-163045 A

  However, the method of detecting the voltage of the capacitor at the time of turning on the power described in Patent Document 1 does not consider that the waveform varies depending on the phase angle at the time of turning on the power, so that the terminal voltage of the capacitor can be detected accurately. Can not. In addition, this document does not disclose a detection circuit corresponding to a power factor correction circuit (PFC (Power Factor Control) circuit). In the method of detecting the terminal voltage of a capacitor when the power is shut down described in Patent Document 2, the characteristics of the capacitor are detected when the power is shut down, so that it is not possible to detect an abnormality such as a capacity loss during the operation of the capacitor. Thus, with the techniques described in Patent Documents 1 and 2, it is difficult to accurately determine the life of the capacitor.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power supply device and a capacitor life determination method that can accurately determine the life of a capacitor that smoothes a direct current.

  A power supply device of the present invention is a power supply device including a smoothing capacitor that smoothes a DC power supply and outputs a DC voltage, and an inverter circuit that converts the DC voltage from the smoothing capacitor into an AC voltage and supplies the AC voltage to a load. And detecting a terminal voltage of the detection capacitor inserted in series between the DC power source and the smoothing capacitor, and immediately after the DC power source is turned on until the inverter circuit is activated. A life detecting means for determining a life of the smoothing capacitor by detecting a voltage change caused by a change in characteristics of the smoothing capacitor based on a terminal voltage of the detecting capacitor detected by the voltage detecting means; , With.

  According to the above configuration, the detection capacitor is inserted in series between the power supply and the smoothing capacitor, and the terminal voltage of the detection capacitor is detected immediately after the power is turned on. Based on the detected terminal voltage of the detection capacitor, Since the life of the smoothing capacitor is determined by detecting the voltage change caused by the characteristic change, the life of the smoothing capacitor can be accurately determined. Note that the voltage change caused by the characteristic change of the smoothing capacitor can be detected by comparing the detected terminal voltage of the detection capacitor with a reference voltage corresponding to the initial terminal voltage of the smoothing capacitor.

  In the above configuration, the life determination unit stops the operation of the inverter circuit when it is determined that the smoothing capacitor has a life.

  According to the above configuration, since the operation of the inverter circuit is stopped when the smoothing capacitor reaches the end of its life, a constant efficiency can always be maintained by replacing the smoothing capacitor that has reached the end of its life.

  Further, in the above configuration, the life determination unit operates using a terminal voltage generated in the detection capacitor as a power source.

  According to the above configuration, since the life determination means operates using the terminal voltage generated in the detection capacitor as a power source, it is possible to reduce costs because it is not necessary to prepare a dedicated power source.

  Further, in the above configuration, the voltage detecting unit has a resistance voltage dividing configuration including a plurality of resistance elements, and includes a switching unit that switches the voltage dividing ratio before and after starting the power supply apparatus.

  According to the above configuration, for example, when a step-down chopper circuit is provided between a diode bridge from which a DC power source is obtained and a smoothing capacitor that outputs a DC voltage by smoothing the DC power source from the diode bridge, the step-down chopper circuit starts. Before, even if the resistor voltage division ratio is reduced and the terminal voltage of the smoothing capacitor is low, A / D conversion of the terminal voltage is possible. During operation of the step-down chopper circuit, the resistor voltage dividing ratio is increased to increase the terminal voltage of the smoothing capacitor. Even if it becomes high, A / D conversion of the terminal voltage becomes possible.

  The illuminating device of this invention was equipped with the said power supply device.

  According to the said structure, the illuminating device which can determine the lifetime of a smoothing capacitor correctly can be provided, and usual efficient illumination is attained.

  A capacitor life determination method according to the present invention is a power supply device including a smoothing capacitor that smoothes a DC power supply and outputs a DC voltage, and an inverter circuit that converts the DC voltage from the smoothing capacitor into an AC voltage and supplies the AC voltage to a load. A smoothing capacitor life judging method for judging the life of the smoothing capacitor, wherein a detection capacitor is inserted in series between the DC power supply and the smoothing capacitor, and immediately after the DC power supply is turned on until the inverter circuit is started During this period, the terminal voltage of the detecting capacitor is detected, and the life of the smoothing capacitor is determined by detecting the voltage change caused by the characteristic change of the smoothing capacitor based on the detected terminal voltage.

  According to the above method, the detection capacitor is inserted in series between the power supply and the smoothing capacitor, the terminal voltage of the detection capacitor is detected immediately after the power is turned on, and the smoothing capacitor is detected based on the detected terminal voltage of the detection capacitor. Since the life of the smoothing capacitor is determined by detecting the voltage change caused by the characteristic change, the life of the smoothing capacitor can be accurately determined. The voltage change caused by the characteristic change of the smoothing capacitor can be detected by comparing the detected terminal voltage with a reference voltage corresponding to the terminal voltage at the initial time of the smoothing capacitor.

  The present invention can accurately determine the life of a smoothing capacitor in a power supply device.

The circuit block diagram of the power supply device which concerns on Embodiment 1 of this invention Waveform diagram for explaining the operation of the power supply device of FIG. The circuit block diagram of the power supply device which concerns on Embodiment 2 of this invention The circuit block diagram of the power supply device which concerns on Embodiment 3 of this invention The circuit block diagram of the power supply device which concerns on Embodiment 4 of this invention

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a circuit configuration diagram of a power supply device according to Embodiment 1 of the present invention. In the figure, a power supply device 1 according to the present embodiment includes a diode bridge 2 for full-wave rectification of an AC voltage, an electrolytic capacitor (smoothing capacitor) 3 for smoothing a DC voltage from the diode bridge 2, a diode bridge 2 and an electrolysis. A detection capacitor 4 inserted in series between the capacitors 3, a bypass thyristor 5 connected in parallel to the detection capacitor 4, and a smoothing capacitor voltage detection circuit (voltage) for detecting the terminal voltage of the detection capacitor 4 Detection means) 6, a reference voltage generation circuit 7 for outputting a reference voltage for comparison with the detection voltage of the smoothing capacitor voltage detection circuit 6, and a detection voltage Vd output from the smoothing capacitor voltage detection circuit 6 and a reference voltage generation circuit 7 is compared, and if the detected voltage Vd is less than the reference voltage Vref, the inverter start signal A microcomputer that operates with a comparison circuit 8 that outputs EN and a DC power source that is output from the diode bridge 2, supplies a DC power source to the smoothing capacitor voltage detection circuit 6, and has a reference voltage generation circuit 7 and a comparison circuit 8 ( Life determination means, hereinafter referred to as “microcomputer”) 9, a control power supply circuit 10 that supplies DC power to the inverter 9, and an inverter circuit that converts the DC voltage obtained by the smoothing action of the electrolytic capacitor 3 into AC voltage and outputs it to the lamp 12 11.

  The thyristor 5 has a cathode connected to one end on the load side (inverter circuit 11 side) of the detection capacitor 4, an anode connected to one end on the power supply side (diode bridge 2 side) of the detection capacitor 4, and a gate connected to the comparison circuit. 8 is connected to the output terminal. The thyristor 5 is turned on (conductive state) when the inverter activation signal EN is output from the comparison circuit 8 and bypasses the detection capacitor 4. The inverter circuit 11 is activated when the inverter activation signal EN is output from the comparison circuit 8. In the present embodiment, as will be described later, since the life of the electrolytic capacitor 3 is determined by detecting the terminal voltage of the detection capacitor 4 before the inverter circuit 11 is activated, the terminal voltage of the detection capacitor 4 is determined. Thus, the inverter circuit 11 is not activated until the thyristor 5 is turned on.

  The smoothing capacitor voltage detection circuit 6 has a resistance voltage dividing structure composed of a plurality of resistance elements, and the voltage dividing ratio can be switched. The microcomputer 9 switches the voltage division ratio in the smoothing capacitor voltage detection circuit 6 according to the state of the input voltage so as to be compatible with various power sources. Thus, the microcomputer 9 also functions as a switching unit that switches the voltage division ratio of the smoothing capacitor voltage detection circuit 6.

  The microcomputer 9 A / D (Analog / Digital) converts the detection voltage Vd output from the smoothing capacitor voltage detection circuit 6 immediately after the DC power supply is supplied from the control power supply circuit 10 and starts up. Measure the voltage. For example, a voltage 140 mV obtained by reducing the terminal voltage Vcx = 1.4 V of the electrolytic capacitor 3 to 1/10 by the smoothing capacitor voltage detection circuit 6 is taken and A / D converted. At this time, if the microcomputer 9 has a 10-bit A / D converter, a data value “28” is obtained. Here, if the terminal voltage Vcx of the electrolytic capacitor 3 becomes 1.7 V, a data value “34” obtained by A / D converting the voltage 170 mV is obtained.

  Here, when the life threshold value of the electrolytic capacitor 3 is the data value “33”, the life of the electrolytic capacitor 3 can be detected. That is, when the data value corresponding to the reference voltage Vref is “33”, the data value “33” and the data value corresponding to the terminal voltage Vcx of the electrolytic capacitor 3 (this data value is the smoothing capacitor voltage detection circuit 6). The deterioration of the electrolytic capacitor 3 can be determined by comparing the data value obtained by A / D conversion of the detection voltage Vd output from the A / D converter. When the electrolytic capacitor 3 deteriorates, the terminal voltage Vcx increases, and the data value becomes equal to or higher than the data value corresponding to the reference voltage Vref. Therefore, the microcomputer 9 determines that the electrolytic capacitor 3 has reached the end of its life.

  When the microcomputer 9 determines that the electrolytic capacitor 3 has reached the end of its life, the microcomputer 9 stops outputting the inverter activation signal EN and outputs a signal S2 for notifying the user. On the other hand, if the electrolytic capacitor 3 has not reached the end of its life, that is, if the data value corresponding to the terminal voltage Vcx of the electrolytic capacitor 3 is less than the data value corresponding to the reference voltage Vref, the microcomputer 9 outputs the inverter activation signal EN. . Further, the microcomputer 9 outputs a signal S1 for switching the voltage dividing ratio of the smoothing capacitor voltage detection circuit 6 to 1: 100 to the smoothing capacitor voltage detection circuit 6. When the inverter start signal EN is output from the microcomputer 9, the thyristor 5 is turned on, and the inverter circuit 11 is started to supply power to the lamp 12.

  Note that noise included in the detection voltage Vd can be removed by capturing the detection voltage Vd output from the smoothing capacitor voltage detection circuit 6 a plurality of times. In addition, the power supply device 1 and the lamp 12 of the present embodiment constitute an illumination device 100.

  Next, the operation of the power supply apparatus 1 having the above configuration will be described with reference to the operation waveform diagram shown in FIG. 2, “DB” is a waveform diagram of the output voltage of the diode bridge 2, “Vcx” is a waveform diagram of the terminal voltage of the electrolytic capacitor 3, and “Vcc” is a waveform diagram of the output voltage of the control power supply circuit 10. “S1” is a waveform diagram showing the operating state of the thyristor 5.

  When the AC power supply PS is turned on to the power supply device 1, the control power supply circuit 10 starts to operate and applies the voltage Vcc to the smoothing capacitor voltage detection circuit 6 and the microcomputer 9. The microcomputer 9 is activated by applying the voltage Vcc (time t1). When the AC power supply PS is turned on, the detection capacitor 4 and the electrolytic capacitor 3 are charged with the peak voltage Vi from the diode bridge 2. By this charging, a terminal voltage Vcx represented by the following expression is generated in the electrolytic capacitor 3. However, the capacitance of the electrolytic capacitor 3 is Cx, and the capacitance of the detection capacitor 4 is Cr.

    Vcx = Vi × Cr / (Cx + Cr)

  Here, for example, when the peak voltage Vi of the AC power supply PS is 141 V, the capacitance Cx of the electrolytic capacitor 3 is 47 μF, and the capacitance Cr of the detection capacitor 4 is 0.47 μF, the electrolytic capacitor 3 has about 1.4 V. The terminal voltage is generated. If the power supply device 1 is used for a long time, the capacitance Cx of the electrolytic capacitor 3 is reduced by 20% to 38 μF, and the capacitance of the detection capacitor 4 does not change. The terminal voltage is about 1.7V.

  The terminal voltage Vcx of the electrolytic capacitor 3 is affected by the input voltage, but can be easily corrected if the microcomputer 9 detects the input voltage. In addition, there is a voltage change due to variations in the capacitances of the electrolytic capacitor 3 and the detection capacitor 4, but the influence can be eliminated by detecting the relative change.

  The microcomputer 9 performs A / D conversion on the detection voltage Vd output from the smoothing capacitor voltage detection circuit 6 immediately after startup, and measures the terminal voltage Vcx of the electrolytic capacitor 3. Then, the degradation of the electrolytic capacitor 3 is determined by comparing the data value corresponding to the measured terminal voltage Vcx with the data value corresponding to the reference voltage Vref. When the deterioration of the electrolytic capacitor 3 is determined, the output of the inverter start signal EN is stopped and the user is notified. When it is determined that the electrolytic capacitor 3 has not deteriorated, the inverter start signal EN is output. Further, the microcomputer 9 gives a signal for switching the voltage dividing ratio of the smoothing capacitor voltage detection circuit 6 to 1: 100 to the smoothing capacitor voltage detection circuit 6.

  When the inverter activation signal EN is output from the microcomputer 9, the thyristor 5 is turned on (t2), and then the inverter circuit 11 is activated (t3). When the thyristor 5 is turned on, a DC voltage is applied to the inverter circuit 11, and the inverter circuit 11 outputs an AC voltage and supplies power to the lamp 12.

  As described above, the power supply device 1 of the present embodiment can detect the terminal voltage of the electrolytic capacitor 3 by inserting the detection capacitor 4 in series between the diode bridge 2 and the electrolytic capacitor 3. The terminal voltage can be detected accurately. Further, the terminal voltage Vd of the detection capacitor 4 is detected immediately after the DC power source PS is turned on and before the inverter circuit 11 is started, and the detection result and the terminal voltage Vd of the detection capacitor 4 at the initial stage of the electrolytic capacitor 3 are equivalent. Therefore, the life of the electrolytic capacitor 3 can be accurately determined.

  Further, since the operation of the inverter circuit 11 is stopped when it is determined that the electrolytic capacitor 3 has a lifetime, it is possible to always maintain a constant efficiency by replacing the electrolytic capacitor 3 whose lifetime has been reached at that time. Further, since the voltage dividing ratio of the smoothing capacitor voltage detection circuit 6 can be changed, it is possible to cope with various power sources by varying the voltage dividing ratio according to the state of the input voltage. Further, since the smoothing capacitor voltage detection circuit 6 and the microcomputer 9 operate with a DC power source from the diode bridge 2, it is possible to reduce costs because it is not necessary to prepare a dedicated power source.

  In the present embodiment, the detection capacitor 4 has a capacitance that is 1 / 100th of the capacitance of the electrolytic capacitor 3, but may be further reduced. In this case, when the capacitance is reduced, the detection voltage is reduced. However, since the variation rate of the detection voltage due to the capacitance change does not change, it can be dealt with by reducing the voltage dividing ratio of the smoothing capacitor voltage detection circuit 6.

  In the present embodiment, the leakage current of the electrolytic capacitor 3 can also be detected by detecting a change in the terminal voltage Vd of the detection capacitor 4 in a short time. That is, when the leakage current increases due to the deterioration of the electrolytic capacitor 3, the charge voltage varies greatly between the initial stage and the last stage, and this may be detected.

(Embodiment 2)
FIG. 3 is a circuit configuration diagram of a power supply device according to Embodiment 2 of the present invention. In this figure, the same reference numerals are given to the portions common to FIG. 1 described above. In FIG. 3, the power supply device 20 of the present embodiment includes a diode bridge 2 for full-wave rectification of an AC voltage, an electrolytic capacitor 3 for smoothing a DC voltage from the diode bridge 2, and between the diode bridge 2 and the electrolytic capacitor 3. Is connected in series, and includes a series circuit 23 including a diode 21, a resistor 22, and a detection capacitor 4, a bypass switch 24 connected in parallel to the series circuit 23, and a smoothing for detecting a terminal voltage of the detection capacitor 4. The capacitor voltage detection circuit 6, the reference voltage generation circuit 7 that outputs a reference voltage Vref for comparison with the detection voltage Vd detected by the smoothing capacitor voltage detection circuit 6, and the detection voltage output from the smoothing capacitor voltage detection circuit 6 Vd is compared with the reference voltage Vref output from the reference voltage generation circuit 7, and the detected voltage Vd is compared with the reference voltage Vr. If less than f, the comparator circuit 8 that outputs the inverter activation signal EN, the switch control circuit 25 that closes the bypass switch 24 when the inverter activation signal EN is output from the comparison circuit 8, and the electrolytic capacitor 3 And an inverter circuit 11 that converts a DC voltage obtained by the smoothing action into an AC voltage and outputs the AC voltage to the lamp 12.

  The diode 21 of the series circuit 23 has an anode connected to one end of the electrolytic capacitor 3 and a cathode connected to one end of the resistor 22. One end of the resistor 22 is connected to the cathode of the diode 21 described above, and the other end is connected to one end of the detection capacitor 4. One end of the detection capacitor 4 is connected to the other end of the resistor 22 described above, and the other end is connected to one of the output ends of the diode bridge 2.

  The reference voltage generation circuit 7, the comparison circuit 8 and the switch control circuit 25 are constituted by a microcomputer (hereinafter referred to as a microcomputer) 27.

  Note that the power supply device 20 and the lamp 12 of the present embodiment constitute an illumination device 101.

Next, the operation of the power supply device 20 configured as described above will be described. When the AC power supply PS is turned on to the power supply device 20, since the bypass switch 24 is open, the electrolytic capacitor 3 and the detection capacitor 4 are charged by the peak voltage Vi of the power supply via the resistor 22. Done. The inverter circuit 11 that is a load is in a stopped state because the inverter activation signal EN has not come. A terminal voltage Vcx represented by the following expression is generated in the electrolytic capacitor 3.
Vcx = Vi × Cx / (Cx + Cr)

  The microcomputer 27 is activated by the terminal voltage of the detection capacitor 4 and detects the terminal voltage of the detection capacitor 4 immediately after activation. Then, the detected voltage Vd corresponding to the detected terminal voltage is compared with the reference voltage Vref, and if the detected voltage Vd is less than the reference voltage Vref, an inverter activation signal EN is output.

  Here, when the peak voltage Vi of the power source is 141 V, the capacitance Cx of the electrolytic capacitor 3 is 47 μF, and the capacitance Cr of the detection capacitor 4 is 470 μF, a voltage of about 23 V is generated in the detection capacitor 4. If the power supply device 20 is used for a long time, the capacitance Cx of the electrolytic capacitor 3 is reduced by 20% to 38 μF, and the capacitance of the detection capacitor 4 does not change. The voltage of the capacitor 4 is about 11V. Assuming that the life of the power supply capacitor 3 is when the electrostatic capacitance Cx of the electrolytic capacitor 3 is reduced to about 20%, the detection voltage Vd can be set to the reference voltage by setting the reference voltage Vref to a value slightly lower than 11V. When Vref or less, the microcomputer 27 stops outputting the inverter activation signal EN and outputs a signal S2 for notifying the user.

  When the detection voltage Vd exceeds the reference voltage Vref and the inverter activation signal EN is output from the microcomputer 27, the switch control circuit 25 closes the bypass switch 24, and then the inverter circuit 11 is activated. As a result, the inverter circuit 11 converts the DC voltage obtained by the smoothing action by the electrolytic capacitor 3 into an AC voltage, supplies power to the lamp 12, and turns on the lamp 12. Further, when the inverter circuit 11 is activated, control power is supplied from the inverter circuit 11 to the microcomputer 27.

  As described above, in the power supply device 20 of the present embodiment, the series circuit 23 including the diode 21, the resistor 22, and the detection capacitor 4 is interposed in series between the diode bridge 2 and the electrolytic capacitor 3. The bypass switch 24 is connected in parallel, and the terminal voltage Vd of the detection capacitor 4 is detected immediately after the DC power source PS is turned on and before the inverter circuit 11 is started. The detection result and the initial detection of the electrolytic capacitor 3 are detected. Since the reference voltage corresponding to the terminal voltage Vd of the capacitor 4 is compared, the life of the electrolytic capacitor 3 can be accurately determined. Further, since the operation of the inverter circuit 11 is stopped when it is determined that the electrolytic capacitor 3 has a lifetime, it is possible to always maintain a constant efficiency by replacing the electrolytic capacitor 3 whose lifetime has been reached at that time.

  Further, since the voltage division ratio of the smoothing capacitor voltage detection circuit 6 can be changed, the life of the electrolytic capacitor 3 can be determined with high accuracy. Further, since the resistor 22 is provided in the series circuit 23, an inrush current when the AC power supply PS is turned on can be prevented. Further, since the smoothing capacitor voltage detection circuit 6 and the microcomputer 27 operate using the terminal voltage generated in the detection capacitor 4 as a power source, it is possible to reduce the cost because it is not necessary to prepare a dedicated power source.

(Embodiment 3)
FIG. 4 is a circuit configuration diagram of a power supply device according to Embodiment 3 of the present invention. In this figure, the same reference numerals are given to the portions common to FIG. 1 described above. In FIG. 4, the power supply device 30 of the present embodiment includes a diode bridge 2 that full-wave rectifies an AC voltage, and a DC voltage from the diode bridge 2 that is stepped down, and an inverter start signal EN that is output from a comparison circuit 8 described later. The step-down chopper circuit 31 that is started up in step S3, the series circuit 33 including the detection capacitor 4 and the resistor 32 connected in parallel between the input and output of the step-down chopper circuit 31, and the electrolytic capacitor that smoothes the DC voltage from the step-down chopper circuit 31 3, a detection capacitor voltage detection circuit 6 for detecting the terminal voltage of the detection capacitor 4, and a reference voltage generation for generating a reference voltage Vref for comparison with the detection voltage Vd output from the detection capacitor voltage detection circuit 6 The detection voltage Vd output from the circuit 7 and the detection capacitor voltage detection circuit 6 and the reference voltage generation circuit 7 The reference voltage Vref is compared, and when the detection voltage Vd exceeds the reference voltage Vref, the comparator circuit 8 that outputs the inverter start signal EN and the DC voltage from the diode bridge 2 operate, and the detection capacitor voltage detection circuit 6 and the microcomputer The control power supply circuit 10 that supplies a DC power supply to each of 34 (hereinafter referred to as a microcomputer) and the inverter start signal EN output from the comparison circuit 8 are started, and the direct current obtained by the smoothing action by the electrolytic capacitor 3 is obtained. And an inverter circuit 11 that converts the voltage into an AC voltage and outputs the converted voltage to the lamp 12.

  One end of the detection capacitor 4 of the series circuit 33 is connected to one of both output ends of the step-down chopper circuit 31, and the other end is connected to one end of the resistor 32. The resistor 32 has one end connected to the other end of the detection capacitor 4 and the other end connected to one of both input ends of the step-down chopper circuit 31. The reference voltage generation circuit 7 and the comparison circuit 8 are constituted by a microcomputer 34.

  Note that the power supply device 30 and the lamp 12 of the present embodiment constitute an illumination device 102.

  Next, the operation of the power supply device 30 having the above configuration will be described. When the AC power supply PS is turned on to the power supply device 30, a current flows through the series circuit 33 of the detection capacitor 4 and the resistor 32 and the electrolytic capacitor 3, and the detection capacitor 4 and the electrolytic capacitor 3 are detected by the peak voltage Vi from the diode bridge 2. Is charged. At the same time, the control power supply circuit 10 starts operating, and supplies DC power to the smoothing capacitor voltage detection circuit 6 and the microcomputer 34 respectively.

A terminal voltage Vcx represented by the following expression is generated in the electrolytic capacitor 3.
Vcx = Vi × Cr / (Cx + Cr)

  Here, when the peak voltage of the AC power supply PS is 410 V, the capacitance Cx of the electrolytic capacitor 3 is 220 μF, and the capacitance Cr of the detection capacitor 4 is 0.1 μF, a voltage of about 190 mV is generated in the electrolytic capacitor 3. . If this power supply device 30 is used for a long time, the capacitance Cx of the electrolytic capacitor 3 is reduced by 20% to 176 μF, and the capacitance Cr of the detection capacitor 4 is not changed. The voltage of the capacitor 3 is about 230 mV.

  The terminal voltage Vcx of the electrolytic capacitor 3 is affected by the input voltage, but can be easily corrected if the microcomputer 34 detects the input voltage. In addition, there is a voltage change due to variations in the capacitances of the electrolytic capacitor 3 and the detection capacitor 4, but the influence can be eliminated by detecting the relative change.

  The smoothing capacitor voltage detection circuit 6 is a resistance voltage dividing circuit that varies the voltage dividing ratio. The microcomputer 34 reduces the resistance voltage dividing ratio before the step-down chopper circuit 31 is activated, and the terminal voltage Vcx of the electrolytic capacitor 3 is low. A / D conversion can be performed, and when the step-down chopper circuit 31 is operated, the resistance voltage dividing ratio is increased so that A / D conversion can be performed even if the terminal voltage Vcx of the electrolytic capacitor 3 is increased. For example, the voltage division ratio until the step-down chopper circuit 31 is started is 1: 2, and the voltage division ratio after the step-down chopper circuit 31 is started is 1: 6. Thus, the microcomputer 34 also functions as a switching unit that switches the voltage division ratio of the smoothing capacitor voltage detection circuit 6.

  The microcomputer 34 performs A / D conversion on the detection voltage Vd output from the smoothing capacitor voltage detection circuit 6 immediately after startup, and measures the terminal voltage Vcx of the electrolytic capacitor 3. For example, before the step-down chopper circuit 31 is started, A / D conversion is performed on a voltage 95 mV that is ½ of the terminal voltage Vcx of the electrolytic capacitor 3.

  When the microcomputer 34 has a 12-bit A / D converter, a data value “76” is obtained if the voltage is 95 mV. If the terminal voltage Vcx of the electrolytic capacitor 3 becomes 230 mV, the data value “92” is obtained by A / D converting 115 mV. When the lifetime threshold value of the electrolytic capacitor 3 is a data value “91”, the lifetime of the electrolytic capacitor 3 can be determined based on the terminal voltage Vcx of the electrolytic capacitor 3. When it is determined that the electrolytic capacitor 3 has reached the end of its life, the microcomputer 34 stops outputting the inverter activation signal EN and outputs a signal S2 for notifying the user. On the other hand, if it is determined that the electrolytic capacitor 3 has not reached the end of its life, the inverter activation signal EN is output, and the signal S1 for switching the voltage dividing ratio of the smoothing capacitor voltage detection circuit 6 to 1: 6 is supplied to the smoothing capacitor voltage detection circuit 6. give. When the inverter activation signal EN is output from the microcomputer 34, the step-down chopper circuit 31 is activated, and power can be supplied to the inverter circuit 11.

  As described above, the power supply device 30 of this embodiment can detect the terminal voltage Vcx of the electrolytic capacitor 3 by connecting the series circuit 33 including the detection capacitor 4 and the resistor 32 in parallel between the input and output of the step-down chopper circuit 31. Thus, the terminal voltage Vcx of the electrolytic capacitor 3 can be accurately detected. Further, the terminal voltage of the detection capacitor 4 is detected immediately after the DC power supply PS is turned on and before the step-down chopper circuit 31 is started up. The detection voltage Vc as the detection result and the detection capacitor 4 at the initial stage of the electrolytic capacitor 3 are detected. Since the reference voltage Vref corresponding to the terminal voltage is compared, the life of the electrolytic capacitor 3 can be accurately determined.

  Further, since the voltage division ratio of the smoothing capacitor voltage detection circuit 6 can be changed, the life of the electrolytic capacitor 3 can be determined with high accuracy. Further, since the smoothing capacitor voltage detection circuit 6 and the microcomputer 34 operate with a DC power source from the diode bridge 2, it is possible to reduce costs because it is not necessary to prepare a dedicated power source.

(Embodiment 4)
FIG. 5 is a circuit configuration diagram of a power supply device according to Embodiment 4 of the present invention. In this figure, the same reference numerals are given to the portions common to FIG. 1 described above. In FIG. 5, a power supply device 40 according to the present embodiment is obtained by adding a communication interface 41 and a communication line 42 to the configuration of the power supply device 1 according to the first embodiment described above. The life detection of the electrolytic capacitor 3 is the same operation as that of the power supply device 1 of the first embodiment, but the control operation at the time of detection is different.

  When the microcomputer 9 </ b> A of the power supply device 40 detects the life of the electrolytic capacitor 3, it transmits a life signal to the communication line 42 via the communication interface 41. The lifetime signal transmitted to the communication line 42 is received by the host controller 50. The host control device 50 also receives a life signal from another power supply device 40. When receiving the life signal, the host controller 50 tests the microcomputer 9A of the power supply device 40 that has transmitted the signal. The test content is a ROM checksum of the microcomputer 9A. When the test is normal, the operating time of the power supply device 40 is confirmed. Here, when the microcomputer 9A of the power supply device 40 includes a storage medium such as an EEPROM (Electrically Erasable and Programmable Read Only Memory), the microcomputer 9A transmits the operating time stored in the storage medium to the host controller 50. .

  If the operating time of the power supply device 40 is within the operating time range in which the power supply device 40 has a lifetime, the host controller 50 determines that the power supply device 40 has a lifetime. And control, such as output fall, is performed with respect to the power supply device 40 which became the lifetime. In addition, the user is notified of a replacement request for the power supply 40 that has reached the end of its life.

  Note that the power supply device 40 and the lamp 12 of the present embodiment constitute an illumination device 103.

  As described above, the power supply device 40 according to the present embodiment is not a life-time operation of the power supply device alone but an accurate life-time determination and a highly convenient power supply by confirming the life detection while checking the microcomputer operation by the host control device 50. A device can be realized.

1, 20, 30, 40 Power supply device 2 Diode bridge 3 Electrolytic capacitor (smoothing capacitor)
4 Detection Capacitor 5 Bypass Thyristor 6 Smoothing Capacitor Voltage Detection Circuit 7 Reference Voltage Generation Circuit 8 Comparison Circuit 9, 9A, 27, 34 Microcomputer 10 Control Power Supply Circuit 11 Inverter Circuit 12 Lamp 21 Diode 22, 32 Resistance 23, 33 Series Circuit 24 Bypass switch 25 Switch control circuit 31 Step-down chopper circuit 41 Communication interface 42 Communication line 50 Host controller 100, 101, 102, 103 Lighting device

Claims (6)

A smoothing capacitor that smooths the DC power supply and outputs a DC voltage;
An inverter circuit that converts a DC voltage from the smoothing capacitor into an AC voltage and supplies the load to a load, and a power supply device comprising:
A detection capacitor inserted in series between the DC power supply and the smoothing capacitor;
Voltage detection means for detecting a terminal voltage of the detection capacitor between immediately after turning on the DC power source and starting the inverter circuit;
Life determination means for determining the life of the smoothing capacitor by detecting a voltage change caused by a characteristic change of the smoothing capacitor based on the terminal voltage of the detection capacitor detected by the voltage detection means;
Power supply unit with   The power supply device according to claim 1, wherein the life determination unit stops the operation of the inverter circuit when it is determined that the smoothing capacitor has a life.   The power supply device according to claim 1, wherein the life determination unit operates using a terminal voltage generated in the detection capacitor as a power supply.   4. The voltage detection unit according to claim 1, wherein the voltage detection unit has a resistance voltage dividing configuration including a plurality of resistance elements, and includes a switching unit that switches a voltage division ratio before and after starting the power supply device. Power supply.   The illuminating device provided with the power supply device in any one of Claims 1 thru | or 4. A capacitor for determining the life of the smoothing capacitor in a power supply device comprising: a smoothing capacitor that smoothes a DC power supply and outputs a DC voltage; and an inverter circuit that converts the DC voltage from the smoothing capacitor into an AC voltage and supplies the AC voltage to a load. A method for determining the life,
A detection capacitor is inserted in series between the DC power supply and the smoothing capacitor, and the terminal voltage of the detection capacitor is detected immediately after the DC power supply is turned on until the inverter circuit is started. A capacitor life determination method for determining a life of the smoothing capacitor by detecting a voltage change caused by a change in characteristics of the smoothing capacitor based on a terminal voltage.

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