JP2012023891A - Power supply device and lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an enabling technique for a power supply device with an electrolytic capacitor to be capable of detecting an abnormality in the electrolytic capacitor with a simple configuration and allowing continuous use of the power supply device even after the abnormality is detected.SOLUTION: A power supply device 100 includes: a DC power supply part (rectification circuit 1 and step-up chopper circuit 2) having a rectification circuit 1 for rectifying an AC voltage supplied from a commercial AC power supply 21 and an electrolytic capacitor C1 for smoothing a rectified voltage rectified by the rectification circuit 1; an inverter circuit 3 for supplying a load 5 with electric power based on the voltage smoothed by the DC power supply part; and a detection circuit 6 for detecting a voltage of the electrolytic capacitor C1 as a detection target and controlling a magnitude of electric power supplied to the load 5 by the inverter circuit 3 according to a range the detected voltage value belonging to.

Description

  The present invention relates to a technique for detecting an abnormality in an electrolytic capacitor in a DC power supply load device equipped with an electrolytic capacitor.

  For example, in an electrolytic capacitor, an aluminum electrode of cathode and anode and electrolytic paper are overlapped and wound into a roll shape and stored in an aluminum case. An external terminal is welded from the aluminum electrode of the cathode and the anode and is taken out of the case. The inside is filled with an electrolytic solution and sealed with a sealing rubber. The head of the aluminum case has a slit generally called a safety valve. This is because the inside of the capacitor generates heat due to an increase in the loss angle (tan δ) inside the electrolytic capacitor, etc., and when the electrolytic solution evaporates rapidly and the internal pressure rises rapidly, this slit portion tears and releases the internal pressure to the outside air.

  There is an electrolyte inside the electrolytic capacitor. When the inside of the capacitor generates heat, the electrolytic solution evaporates and the capacitor internal pressure increases. Even in the initial state, there is internal heat generation and the electrolytic solution evaporates, but it passes through the sealing rubber and maintains the balance between the internal pressure and the outside air. However, when used for a long time, the electrolytic solution decreases and the loss angle (tan δ) of the capacitor increases. As the loss angle increases, the inside of the capacitor generates heat, and the evaporation of the electrolyte is promoted. For this reason, the permeation from the sealing rubber is insufficient, and the internal pressure of the capacitor increases. For this reason, the safety valve in the head may be torn, and the internal electrolyte may be ejected in the form of water vapor to the outside.

  This phenomenon occurs not only when used for a long time, but also when the voltage applied to the capacitor exceeds the rated voltage or when a reverse voltage is applied. If the electrolyte is generated in a state where it remains sufficiently, more electrolyte is ejected in the form of water vapor. The main component of the electrolytic solution is ethylene glycol, and the boiling point is about 200 ° C.

  For example, electrolytic capacitors are also used in high-frequency conversion circuits such as switching power supplies and inverter circuits. The capacitance of the electrolytic capacitor is approximately several μF to several hundred μF, and the rated voltage is several V to several hundred V. The electrolytic capacitor generates heat in the capacitor at the end of its life or at the end of its life, the electrolytic solution evaporates, the safety valve opens, and the electrolytic solution is ejected in the form of water vapor.

  From the viewpoint of end users who use electronic devices, this phenomenon is often perceived as smoke generated by combustion, and is now regarded as a problem in recent years when the safety of electronic devices has been highlighted.

  In order to avoid this phenomenon, a technique (for example, Patent Document 1) that electrically detects a change in the current flowing through the electrolytic capacitor and an applied voltage, or a temperature sensing element in which the heat generated by the electrolytic capacitor is incorporated in the electrolytic capacitor. There exists a technique (for example, patent document 2) detected by the above.

Japanese Patent Publication No. 4-59592 JP-A-4-233214

  However, in Patent Document 1 and Patent Document 2, when the current flowing through the electrolytic capacitor, the applied voltage, or the heat generation is detected and the predetermined level is exceeded, the operation of the device stops. For example, if a lighting fixture or the like is turned off immediately after the end of life is detected, there is often no light until the lighting fixture is replaced.

  In addition, there is a function of turning on the LED just before the end of the life of the electrolytic capacitor or notifying the replacement time of the device by voice. However, it is desirable to avoid as much as possible the complexity of the circuit configuration for functions that are used for only a short time during the life cycle of the device.

  An object of the present invention is to provide a technique for detecting an abnormality of an electrolytic capacitor with a simple configuration in a power supply device equipped with an electrolytic capacitor, and enabling the use of the power supply device to be continued even after the abnormality is detected.

  A power supply device according to the present invention includes a rectifier circuit that rectifies an AC voltage supplied from a commercial AC power supply, a DC power supply unit that includes an electrolytic capacitor that smoothes the rectified voltage rectified by the rectifier circuit, and the DC power supply unit. Any one of a supply unit that supplies power based on the smoothed smoothed voltage to a predetermined load, a voltage of the electrolytic capacitor, a current flowing through the electrolytic capacitor, and a temperature of the electrolytic capacitor, And a control unit that controls the magnitude of the power supplied to the load by the supply unit according to a range to which the detected value of the detection target is detected. .

  According to the present invention, when the capacity of the electrolytic capacitor mounted on the power supply device decreases with time, the load output is reduced in stages, thereby preventing the safety valve of the electrolytic capacitor from operating. The life cycle can be extended. Further, by controlling the magnitude of the supplied power, for example, when the load is a light source, it gradually becomes dark, so that the user can know a decrease in load capability. For this reason, the user can smoothly exchange the devices.

FIG. 3 is a circuit diagram illustrating the power supply device 100 according to the first embodiment. FIG. 5 is a diagram illustrating voltage characteristics of the electrolytic capacitor C1 in the first embodiment. FIG. 5 shows waveforms of respective parts in the first embodiment. FIG. 6 is a circuit diagram showing a power supply device 100 according to a second embodiment. FIG. 6 is a circuit diagram illustrating a power supply device 100 according to a third embodiment. FIG. 9 is a perspective view showing the arrangement of temperature detection blocks 16 in the third embodiment.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram of a power supply device 100 for a fluorescent lamp according to the first embodiment.

  Next, the circuit configuration of the power supply device 100 of FIG. 1 will be described. The power supply apparatus 100 includes a rectifier circuit 1 that rectifies an AC voltage input from a commercial AC power supply 21, a boost chopper circuit 2 that boosts a voltage output from the rectifier circuit 1, and a voltage output from the boost chopper circuit 2 as a high-frequency current. An inverter circuit 3 (supply unit) that converts power into a load 5 connected via a load circuit 4 and a detection circuit 6 (control unit) that detects a DC voltage generated across the electrolytic capacitor C1. It has. The rectifier circuit 1 and the step-up chopper circuit 2 constitute a “DC power supply unit”.

(Boost chopper circuit 2)
The step-up chopper circuit 2 has an electrolytic capacitor C1 that smoothes the voltage that is rectified by the rectifier circuit 1 and further boosted by switching of the switching element Q1. The power supply device 100 is characterized in that it detects the voltage of the electrolytic capacitor C1 and controls the drive frequency of the inverter circuit 3 based on the detection result of the voltage, thereby executing control for reducing the output of the load.
The step-up chopper circuit 2 is connected in parallel to the output terminal of the rectifier circuit 1, connected in series with pulsating voltage detection resistors R4 and R5 for detecting the pulsating voltage, and a switching element Q1 connected via the transformer T1. A current detection resistor R6 for detecting a current flowing through the switching element Q1, a diode D1 connected to the anode side of the transformer T1, an electrolytic capacitor C1 connected to the cathode side of the diode D1 and the low potential side of the rectifier circuit 1, A series connection of output voltage detection resistors R1 and R2, which are connected in parallel to the electrolytic capacitor C1 and detect a voltage charged in the electrolytic capacitor C1, and pulsating voltage detection resistors R4 and R5 and output voltage detection resistors R1 and R2 and switching. The detection signal detected by the current detection resistor R6 of the element Q1 and the detection signal generated on the secondary side of the transformer T1 are input, and these Based on the output signal, and a step-up chopper control circuit 7 for controlling the switching element Q1.

(Inverter circuit 3)
The inverter circuit 3 supplies power to the load 5 based on the voltage boosted and smoothed by the boost chopper circuit 2 (smoothing voltage). That is, the inverter circuit 3 includes switching elements Q2 and Q3 connected in series, and a switching control circuit 8 that generates a signal for alternately turning on and off the switching elements Q2 and Q3 at a high frequency. The switching control circuit 8 changes the frequency of the high-frequency switching signal output from the terminal B according to the current value flowing out from the terminal A of the switching control circuit 8.

(Load circuit 4)
The load circuit 4 is connected to the load 5 through a ballast choke L20 from a connection point between the switching element Q2 and the switching element Q3, and constitutes a series resonance circuit including a capacitor C20 for removing a DC component between the load 5 and the ground. . The load 5 will be described below using a fluorescent lamp as an example.

(Detection circuit 6)
The detection circuit 6 includes a voltage detection block 10, a first threshold circuit block 11, a second threshold circuit block 12, a first signal processing block 13, and a second signal processing block 14.
(1) The voltage detection block 10 detects the voltage across the electrolytic capacitor C1 (an example of a detection target).
(2) The first threshold circuit block 11 compares the voltage detected by the voltage detection block 10 with its first threshold.
(3) The second threshold circuit block 12 also compares the voltage detected by the voltage detection block 10 with its second threshold.
(4) The first signal processing block 13 outputs a signal for increasing the frequency to the switching control circuit 8 when the detected voltage exceeds the first threshold value of the first threshold circuit block 11.
(5) The second signal processing block 14 outputs a signal for increasing the frequency to the switching control circuit 8 when the detected voltage exceeds the second threshold value of the second threshold circuit block 12. In (4) and (5), when the detected voltage exceeds the first threshold value and the second threshold value, a signal for increasing the frequency is output. This is because the fluorescent lamp (light source) that is the load 5 is increased when the frequency is increased. This is because it is assumed that the light output of the light source is reduced. That is, the first signal processing block 13 and the second signal processing block 14 output a signal that reduces the power consumption of the load when the detected voltage exceeds the first threshold value and the second threshold value.

  Next, the operation of the power supply apparatus 100 will be described. When power from the commercial AC power supply 21 is supplied to the power supply device 100, the boost chopper circuit 2 operates and a boosted DC voltage is applied to the inverter circuit 3.

  A signal is generated from the switching control circuit 8 so that the switching elements Q2 and Q3 of the inverter circuit 3 are alternately turned on and off, and a high-frequency rectangular wave is generated between the connection point of the switching elements Q2 and Q3 and the low potential side of the electrolytic capacitor C1. Voltage is generated.

  This rectangular wave high frequency voltage is applied to the load 5 through the load circuit 4. The ballast choke L20, the load 5, and the capacitor C20 are a series resonance circuit, and high-frequency current flows through the load circuit 4 and the load 5.

  The voltage detection block 10 of the detection circuit 6 is connected to both ends of the electrolytic capacitor C1. The voltage detection block 10 divides the peak voltage across the electrolytic capacitor C1 with, for example, a resistor. This divided voltage is input to the first threshold circuit block 11 and the second threshold circuit block 12, and is compared with the voltage of each internal threshold. The internal threshold (first threshold) of the first threshold circuit block 11 is a voltage lower than the internal threshold (second threshold) of the second threshold circuit block 12.

  When the voltage detected by the voltage detection block 10 exceeds the internal threshold value of the first threshold circuit block 11, a signal is output from the first threshold circuit block 11 to the first signal processing block 13, and the first signal processing block 13 is an inverter circuit. 3 outputs a signal for increasing the switching frequency of the switching elements Q2 and Q3.

  When the voltage detected by the voltage detection block 10 exceeds the internal threshold of the second threshold circuit block 12, a signal is output from the second threshold circuit block 12 to the second signal processing block 14, and the second signal processing block 14 is an inverter circuit. 3 outputs a signal for increasing the switching frequency of the switching elements Q2 and Q3. The signal output from the second signal processing block 14 is a signal instructing to further increase the oscillation frequency (make the fluorescent lamp as the load 5 darker) than the signal output from the first signal processing block 13.

The processing contents of the above detection circuit 6 will be described with reference to FIGS.
FIG. 2 is a diagram illustrating the voltage across the electrolytic capacitor C1.
(A) is the voltage across the electrolytic capacitor C1 in the initial lighting state, and has a ripple voltage Vp-p. This is because the load circuit 4 consumes current.
(B) is the voltage across the electrolytic capacitor C1 when the fluorescent lamp as the load 5 continues to be lit. The capacitance of the electrolytic capacitor C1 gradually decreases and the current consumed in the load circuit is constant, so the ripple voltage Vp-p increases.
(C) is a case where the lighting time is further increased from (b). The capacity of the electrolytic capacitor C1 is further reduced, and the ripple voltage Vp-p is further increased.

FIG. 3 shows the waveform of each part from the start of lighting to the end of life of the electrolytic capacitor C1. The horizontal axis of the waveform is time. The vertical axis represents the value of each voltage and each signal.
(A) is a voltage waveform across the electrolytic capacitor C1 when lighting continues.
(B) is an internal threshold voltage of the second threshold circuit block 12.
(C) is an internal threshold voltage of the first threshold circuit block 11.
(D) is an output voltage of the voltage detection block 10.
(E) is an output signal of the second threshold circuit block 12.
(F) is an output signal of the first threshold circuit block 11.
(G) is the oscillation frequency of the inverter circuit 3.
(H) is the illuminance of the lamp 5.

Next, the operation in the process of the electrolytic capacitor C1 from the start of lighting to the end of its life will be described with reference to FIG.
(1) As in (a), the ripple voltage Vp-p of the voltage across the electrolytic capacitor C1 rises as the lighting time elapses. Accordingly, the voltage (d) obtained by dividing the peak voltage across the electrolytic capacitor C1 by the voltage detection block 10 also increases.
(2) The time when the decrease in the capacity of the electrolytic capacitor C1 from the start of lighting is equal to or less than the specified capacity is defined as T1, and this T1 is defined as the lifetime of the electrolytic capacitor C1.
(3) As shown in (d), the internal threshold value of the first threshold circuit block 11 is the voltage at the time when the electrolytic capacitor after the elapse of T1 has reached the capacity defined as the lifetime.
(4) When the output voltage (d) of the voltage detection block 10 exceeds the internal threshold (c) of the first threshold circuit block 11, the output signal (f) from the first threshold circuit block 11 toward the first signal processing block 13 Is output. In response to this output signal (f), the first signal processing block 13 outputs to the switching control circuit 8 a signal that increases the oscillation frequency of the inverter circuit 3 output from the switching control circuit 8.
(5) As a result, the current flowing through the load 5 decreases and the power consumed by the load 5 decreases. Here, since the load 5 is a fluorescent lamp, it enters a dimming state, and the illuminance of the lamp decreases.
(6) When the power consumption of the load 5 decreases, the current discharged from the electrolytic capacitor C1 decreases, so that the increase in the peak voltage of the electrolytic capacitor C1 after the lapse of T1 stops or decreases.
(7) When more time elapses with the power consumption of the load 5 decreased at T1, the capacity of the electrolytic capacitor C1 further decreases, and the peak voltage of the electrolytic capacitor C1 begins to rise again.
(8) Then, the output voltage (d) of the voltage detection block 10 further increases and reaches the internal threshold voltage of the second threshold circuit block 12 (time T2). At this time, the capacity of the electrolytic capacitor C1 is less than the capacity at the time of the life set at the time of design, but since the power consumption of the load 5 is reduced, the load of the electrolytic capacitor C1 is also reduced. Does not work.
(9) When the output voltage (d) of the voltage detection block 10 rises and reaches the internal threshold voltage of the second threshold circuit block 12, the second signal processing is performed as described in (4) to (7) above. The block 14 outputs a signal that further increases the oscillation frequency of the inverter circuit 3 output from the switching control circuit 8 to the switching control circuit 8.
(10) As a result, the current flowing through the load 5 is further reduced from the above (5), the power consumed by the load 5 is further reduced, and the illuminance of the lamp is further reduced.

  As described in (1) to (10) above, the detection circuit 6 (detection unit, control unit) detects the voltage of the electrolytic capacitor C1 as a detection target, and inverts the inverter according to the range to which the detected voltage value belongs. The amount of power supplied from the circuit 3 to the load 5 is controlled.

  In the first embodiment, there are two threshold circuit blocks, but two or more threshold circuit blocks may be provided.

  As shown in FIG. 3, the detection circuit 6 determines to which range of the plurality of ranges set in advance that the detected voltage of the electrolytic capacitor C1 does not overlap with other ranges (for example, the first A range less than one threshold, a range greater than or equal to the first threshold and less than the second threshold, or a range greater than or equal to the second threshold). The greater the value of the determined range, the smaller the electric power applied to the inverter circuit 3 To supply. In this way, when the capacity of the electrolytic capacitor falls below the design life capacity, the load supply power is decreased step by step, and the load is not stopped and the user is informed that the capacity of the load has decreased. The stress on the electrolytic capacitor can also be reduced, and the safety valve operation can be prevented.

  In the first embodiment, the case where the inverter circuit 3 supplies high-frequency power to the load 5 as power based on the smoothed voltage smoothed by the electrolytic capacitor C1 is described as an example. When direct current power is supplied to a predetermined load as power based on the smooth voltage, a configuration for controlling the magnitude of the direct current power may be used.

Embodiment 2. FIG.
FIG. 4 is a circuit diagram of the power supply device 100 according to the second embodiment. FIG. 4 shows a configuration in which the voltage detection block 10 of the detection circuit 6 in the first embodiment is replaced with a current detection block 15.

  The detection circuit 6 in FIG. 4 includes a current detection block 15 that detects a current (an example of a detection target) flowing through the electrolytic capacitor C1 in series with the electrolytic capacitor C1.

  It is known that the capacity of the electrolytic capacitor C1 decreases with time, and the ripple voltage and ripple current increase. The current detection block 15 in FIG. 4 is connected in series with the electrolytic capacitor C1.

  As the current detection means of the current detection block 15, for example, a current transformer or a resistor having a low resistance value for current detection is used.

  The signal detected by the current detection block 15 is connected to the switching control circuit 8 via a plurality of threshold circuit blocks and signal processing blocks in the subsequent stage, as described in the first embodiment.

  When the capacitance of the electrolytic capacitor decreases due to aging, the ripple current increases and the detection current also increases. This change is determined by a plurality of threshold circuit blocks in the same manner as in the first embodiment, and the load power is reduced stepwise as the capacity of the electrolytic capacitor C1 decreases.

Embodiment 3 FIG.
FIG. 5 is a circuit diagram of the power supply device 100 according to the third embodiment. FIG. 5 shows a configuration in which the voltage detection block 10 of the detection circuit 6 in the first embodiment is replaced with a temperature detection block 16. The temperature detection block 16 detects the temperature of the electrolytic capacitor C1 (an example of a detection target).

  FIG. 6 is a perspective view showing a state in which the temperature detection block 16 is attached to the aluminum case of the aluminum electrolytic capacitor C <b> 1 disposed on the substrate 17. As shown in FIG. 6, the temperature detection block 16 is attached to the side surface of the electrolytic capacitor C1. It is known that due to aging, the electrolytic capacitor C1 increases its internal resistance value when its capacity decreases, and the temperature of the electrolytic capacitor C1 increases due to a ripple current.

  When the capacity of the electrolytic capacitor C1 decreases due to aging, the ripple current increases, the internal resistance value increases, and the electrolytic capacitor C1 generates heat. This change is determined by a plurality of threshold circuit blocks in the same manner as in the first embodiment, and the load power is reduced stepwise as the capacity of the electrolytic capacitor C1 decreases.

  In addition, although Embodiment 1-3 demonstrated the power supply device, it is of course possible to set it as the embodiment of the lighting fixture provided with the power supply device in any one of Embodiment 1-3.

  1 rectifier circuit, 2 boost chopper circuit, 3 inverter circuit, 4 load circuit, 5 load, 6 detection circuit, 7 boost chopper control circuit, 8 switching control circuit, 10 voltage detection block, 11 first threshold circuit block, 12 second Threshold circuit block, 13 First signal processing block, 14 Second signal processing block, 15 Current detection block, 16 Temperature detection block, 21 Commercial AC power supply, 100 power supply, R4 to R5 Pulsating current detection resistor, T1 transformer, Q1 Switching element, R6 current detection resistor, R1-R2 output voltage detection resistor, D1 diode, C1 electrolytic capacitor, Q2-Q3 switching element, L20 ballast choke, C20 capacitor for removing DC voltage component, F current fuse.

Claims (6)

A DC power supply unit having a rectifier circuit for rectifying an AC voltage supplied from a commercial AC power supply, and an electrolytic capacitor for smoothing the rectified voltage rectified by the rectifier circuit;
A supply unit that supplies power based on the smoothed voltage smoothed by the DC power supply unit to a predetermined load;
Any one of the voltage of the electrolytic capacitor, the current flowing through the electrolytic capacitor, and the temperature of the electrolytic capacitor is detected as a detection target, and according to the range to which the detected value of the detected detection belongs And a control unit that controls the magnitude of the electric power supplied to the load by the supply unit. The controller is
It is determined which range of the plurality of ranges that are set in advance so that the detected value is not overlapped with other ranges, and the larger the value of the determined range is, the smaller the power is supplied to the supply unit The power supply apparatus according to claim 1, wherein the power supply is supplied to the load. The load is
It is a light source that emits light when supplied with power,
The controller is
The power supply apparatus according to claim 2, wherein the supply unit is controlled such that the illuminance of the light source decreases as the determined range value increases. The supply unit
4. The power supply device according to claim 1, wherein either high frequency power or direct current power is supplied to the load as the power based on the smoothing voltage. 5. The electrolytic capacitor is
5. The power supply device according to claim 4, wherein the power supply device is an aluminum electrolytic capacitor.   A lighting fixture comprising the power supply device according to claim 1.

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