JPS6016170B2 - DC power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC power supply device most suitable for compensating for instantaneous power outages.

A secondary DC power supply device is generally configured to convert AC supplied from an AC power supply 1 into DC using a rectifier 2, as shown in FIG. 1, and supply DC power to a load 4 via a smoothing capacitor 3. ing.

In such a DC power supply, the capacity of the smoothing capacitor 3 may be increased to compensate for instantaneous voltage drops or instantaneous power outages, and this may also be used as a capacitor for compensating for instantaneous power outages. By the way, the second form of instantaneous power outage is
It can be roughly classified into three types shown in Figures A, B, and C.

The waveforms in FIG. 2 are explanatory representations of the voltage (Vin) at the output stage of the rectifier 2 in the case where the capacitor 3 does not have a compensation function, without considering ripple current. Figure 2A
Figure 2B shows a power outage mode in which the voltage Vin becomes zero volts at time t, and then gradually increases, returning to the normal state at time 2. Figure 2B shows the voltage Vin reaching zero volts from time t to t2. FIG. 2C shows a power outage mode in which the voltage remains at zero volts until time t, and then the voltage gradually increases from t2, returning to the normal state at time t. The present invention provides an apparatus that is particularly suitable for compensating voltages in the power outage regimes shown in FIGS. 2A and 2C. In a conventional power failure compensation circuit in which the capacity of the smoothing capacitor 3 is simply increased, the power failure conditions shown in Figure 2 A, B, and C are changed to Figure 3 A.
, B, and C, and in either case, the output voltage Vc decreases as the capacitor 3 discharges.

Therefore, in the case of a load that requires a stabilized voltage, the capacitance of the capacitor 3 must be increased to reduce the voltage drop. As a result, the cost and size of the device have increased. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a DC power supply device that can reduce voltage changes during momentary power outages or significant voltage drops, and that can reduce the size and size of the device and reduce costs. It is in.

To achieve the above object, the present invention provides a rectifier connected to an AC power source that is likely to cause a momentary power outage or voltage drop that recovers in a form that gradually increases after the power source voltage falls below a predetermined value; a pair of DC power supply lines for supplying power from the DC power supply lines to the load; a reverse current blocking circuit, such as the diode 23 of the embodiment, connected in series to one of the pair of DC power supply lines; a compensation capacitor, one end of which is connected to the one DC power supply line on the output side of the reverse current blocking circuit; and a terminal of the compensation capacitor and the other DC power supply line of the pair of DC power supply lines. a compensation capacitor charging circuit, such as the high resistance 17 of the embodiment, connected between the one DC power supply line and the other end of the compensation capacitor on the input side of the reverse current blocking circuit; a smoothing capacitor connected between the one DC power supply line and the other DC power supply line on the output side of the reverse current blocking circuit; and a terminal voltage of the smoothing capacitor. is configured to detect that the voltage has become below a predetermined level, and based on this detection, form a signal to turn on the switch and supply it to the switch, and the smoothing capacitor works as a power source to turn on the switch. a voltage detection and switch control circuit connected to form a control signal, and when the AC power supply is normal, the compensation capacitor and the smoothing capacitor are connected via the rectifier and the reverse current blocking circuit. and supplies power to the load at the same time as charging the AC power supply, and after the voltage of the AC power supply becomes equal to or lower than the predetermined level, the rectifier The present invention relates to a DC power supply device configured to supply the load with a voltage obtained by adding the voltage of the compensation capacitor to the output voltage of the DC power supply. According to the above invention, the following effects can be obtained. [B] During a momentary power outage or voltage drop and during recovery, the rectifier, switch, and compensation capacitor are connected in series, so if the power supply voltage gradually increases when the power supply voltage is restored, the voltage of the compensation capacitor The drop is compensated by the rectifier voltage, and
Changes in voltage applied to the load are reduced. 'o} During a complete power outage period when the input and output of the rectifier are zero, when the switch is turned on, the smoothing capacitor and the compensation capacitor are connected in parallel, so both capacitors supply power to the load. It is possible to suppress a significant voltage drop. (1) Since the voltage detection and switch control circuit operates using the smoothing capacitor as a power source, it is possible to perform voltage compensation in the event of a power outage or voltage drop without the need to provide a separate power source.

0 During voltage compensation, substantially all of the charge of the compensation capacitor can be used, so the capacitance of the capacitor can be reduced, and the device can be made smaller.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 4 is a principle circuit diagram showing a DC power supply device with an instantaneous power failure compensation circuit according to the present invention. This DC power supply has a main circuit that converts AC supplied from an AC power supply 11 into DC using a rectifier 12 and supplies this to a load 14 via a smoothing capacitor 13. A compensation capacitor 8 is connected between the power supply line 16 of switch 21 and switch 21 connected to
It has a power outage detection and switch control circuit 22 that controls the power outage detection and switch control circuit. A diode 23 connected in series to the line between one end of the compensation capacitor 18 and the output point 20 is a diode for blocking reverse current. In this circuit, load 14 is a load equipped with a voltage stabilization circuit. When AC power is normally supplied from the AC power supply 11 in the above circuit,
DC power is supplied to the load 14 via the rectifier 12 and the smoothing capacitor 3.

At the same time, the compensation capacitor 18 is charged via the resistor 17 to approximately the rectifier output voltage. At this time, the switch 21 is held off. As shown in Fig. 5, a momentary power outage occurs in the Ingawa River, and the voltage Vjn at the output point of the rectifier 12 becomes the state shown by the dotted line in Fig. 6A. If so, the power outage is detected by the power outage detection and switch control circuit 22 and the switch 21 is turned on.

As a result, a circuit consisting of the rectifier 12, the switch 21, the compensation capacitor 8, and the load 14 is formed, and the voltage that is the sum of the power supply voltage yin at the output point of the rectifier 12 and the voltage Vco of the compensation capacitor 8 is used for smoothing. It is applied to a load 14 via a capacitor 3. The power supply voltage yin gradually increases as shown by the dotted line in FIG. 5A, and the compensation capacitor voltage Vco gradually decreases as shown by the chain line.
If the slope of the compensation capacitor voltage Vco and the slope of the power supply voltage Vjn are made equal and opposite in value, Vin
The output voltage Vc, which is the sum of
becomes constant as shown by the solid line. During power outage periods, the voltage on the anode side of diode 23 is lower than the voltage on the cathode side, so diode 23 remains non-conducting and no backflow occurs. When the power supply voltage Vin returns to the normal value at time t2, the switch 21 is turned off, while the diode 23 is turned conductive, and power is again supplied to the load 14 based on the power supply voltage. At the same time, charging of the compensation capacitor 8 is started in preparation for the next power outage. Next, the case of the power outage mode shown in FIG. 2C will be described. FIG. 6 shows the state of voltage compensation in this power outage mode. If the power goes out at that time, switch 21 will be turned on. However, since the power supply voltage Vin is not generated until time 3, power is supplied to the load 14 only by the discharge of the compensation capacitor 8. Therefore, the output voltage Vc decreases somewhat. At time t2, the power supply voltage Vin changes to A in FIG.
Since the voltage is generated as shown by the dotted line, the voltage that is the sum of the compensation capacitor 8 and the power supply voltage Vin becomes the output voltage Vc. When the normal state is reached at time t3, the switch 21 is turned off and the normal power supply state is established. In the case of this power outage type, some voltage fluctuation occurs, but it is easy to suppress the voltage fluctuation to an allowable range. FIG. 7 is a circuit diagram showing the circuit of FIG. 4 in more detail.

Components designated by numerals 11 to 23 in this drawing have the same functions as those of the same numerals in FIG. The switch 21 in FIG. 4 is shown as a thyristor switch 21a in FIG. The anode of the thyristor switch 21a is connected to the point 2 via the resistor 24, and the cathode is connected to the point 19. The gate of the thyristor is connected via a resistor 25 to a pulse transformer 26 of a power failure detection and switch control circuit 22. 2
Reference numeral 7 denotes a detection transistor, the base of which is connected to the positive power supply line 15 via a resistor 28 and a diode 29, the emitter connected to the negative power supply line 16, and the collector connected to the positive power supply line 16. is connected between the resistor 30 and the capacitor 31. One base electrode of the junction transistor, that is, the UJT 32, is connected to the positive power supply line 15 via the resistor 33, and the other base electrode is connected to the negative power supply line 16 via the primary winding of the pulse transformer 26. has been done. If a power outage occurs in this circuit and the output voltage Vc drops slightly, the Jenner diode 29, which has been in a conductive state until now, becomes non-conductive, and the transistor 27 is turned off.

As a result, carrier injection from the emitter of the UJT 32 causes the pulse transformer 26 to generate a trigger pulse. The IJ pulse generated by the pulse transformer 26 is applied to the thyristor switch 21a, which turns on. The thyristor switch 21a may be kept in the on state as shown in FIG. 5 during the power outage period, but in this specific example, since the power supply voltage Vin is a pulsating current, the thyristor switch 21a is intermittently turned on. FIG. 8 shows the voltage and current of each part in detail. In FIG. 8A, the dotted line shows the power supply voltage Vin, the chain line shows the voltage Vco of the compensation capacitor 18, and the solid line shows the output voltage yc. It is shown.

FIG. 8B shows the current LscR of the thyristor 21a. If a power outage occurs in the form shown in FIG. 2A at the time shown in FIG. 8, the power supply voltage Vin decreases and the output voltage V
c also decreases. When the output voltage Vc drops to the predetermined level Vr, the transistor 27 is turned off as described above, and the pulse transformer 26 generates a trigger pulse. resistance 30
Since the time constant of the circuit consisting of and capacitor 31 is set to be extremely small, a trigger pulse is generated after a very short time when transistor 27 is turned off. When the thyristor 21a receives a trigger pulse and turns on at a certain time, a circuit including the rectifier 12, the resistor 24, the thyristor 21a, and the compensation capacitor 18 is formed, and the voltage is the sum of the power supply voltage Vin and the compensation capacitor voltage Vco. Smoothing capacitor 13 is charged. Therefore, the smoothing capacitor 13
The voltage Vc increases as shown in FIG. 8A. As the smoothing capacitor is charged by the power supply voltage Vin and the compensation capacitor voltage Vco, the compensation capacitor voltage Vco
decreases, and the current voltage Vi obtained by full-wave rectification of the sine wave AC
n reaches its maximum half-wave value and begins to decrease at time. Therefore, the anode of the thyristor 2 receiving the power supply voltage Vjn is
1a is in a reverse bias state, and 1a is turned off. When the thyristor 21a is turned off, the discharge of the compensation capacitor 18 is also stopped, and the voltage Vco is kept constant for now. Since the output voltage Vc of the smoothing capacitor 13 is supplying power to the load 14, it gradually decreases and reaches the predetermined level Vr again, and a trigger pulse is applied to the thyristor 21a. As a result, the thyristor 21a is turned on from t4 to t5, and the power supply voltage Vin and the compensation capacitor voltage V
The smoothing capacitor 13 is charged by CO.
If the power outage is restored after repeating these operations, the thyristor 21a will no longer be turned on, and the diode 23 will be in a conductive state, resulting in a normal power supply state.
At the same time, the compensating capacitor 18, which has been completely discharged, is charged. As can be understood from the explanation up to this point, in the above-mentioned device, the output voltage does not change much even if there is a power outage.

Therefore, stable DC power can be supplied. Furthermore, since almost all of the charge of the compensating capacitor 18 can be used, the capacitor capacity can be reduced.
That is, even if the sum of the capacitance of the smoothing capacitor 13 and the capacitance of the compensation capacitor 18 is smaller than the capacitance of the subordinate capacitor. Furthermore, if the capacitor capacity is the same as that of a conventional capacitor, it is possible to compensate for a power outage for a longer period of time than conventionally. Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be further modified.

For example, another switching element such as a transistor may be used in place of the sirensor 21a. Also, switch 2
The voltage value of Vin added to Vco during a power outage period may be adjusted by the control of 1 or by providing an independent voltage adjustment circuit. In this case, it is convenient to use a transistor for the switch 21 and perform switching and voltage adjustment with the transistor. Further, a smoothing circuit may be provided to smooth the voltage Vin applied via the switch 21 in FIG. Furthermore, the manner in which the switch 21 is turned on during a power outage period may be changed. That is, it may be turned on continuously as shown in FIG. 5B, or it may be turned on intermittently as shown in FIG. 8B'. Alternatively, a switch circuit may be connected in place of the resistor 17, and the switch may be turned on only during charging.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a conventional DC power supply device, Fig. 2 is a waveform diagram illustrating the mode of power outage using power supply voltage Vin, and Fig. 3
The figure shows the state of power failure compensation by the circuit in Figure 1 with the output voltage Vc
4 is a circuit diagram showing the principle of a DC power supply device according to an embodiment of the present invention, FIG. 5 is a waveform chart showing the state of each part in FIG. 4, and FIG. A waveform diagram illustrating the state of each part in Fig. 4 in another power outage mode, Fig. 7 is a circuit diagram showing the circuit in Fig. 4 in more detail, and Fig. 8 is a diagram showing the state of each part in Fig. 7. FIG. 3 is a waveform diagram showing the state. In the symbols used in the drawings, 11 is an AC power supply, 12 is a rectifier, 13 is a smoothing capacitor, 14 is a load, 15 and 16 are power lines, 17 is a resistor, 18 is a compensation capacitor, and 21 is a The switch 22 is a power failure detection and switch control circuit, and 23 is a reverse current blocking diode. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A rectifier connected to an alternating current power source that is likely to cause a momentary power outage or voltage drop that recovers in the form of a gradual increase after the power supply voltage drops below a predetermined value, and a pair for supplying power from the rectifier to a load. a DC power line, a reverse current blocking circuit connected in series to one of the DC power lines of the pair of DC power lines, and one end thereof connected to the one DC power line on the output side of the reverse current blocking circuit. a compensation capacitor connected to the compensation capacitor; a compensation capacitor charging circuit connected between the other end of the compensation capacitor and the other DC power supply line of the pair of DC power supply lines; and a compensation capacitor charging circuit connected to the reverse current blocking circuit. A switch connected between the one DC power line and the other end of the compensation capacitor on the input side, and a switch connected between the one DC power line and the other end of the compensation capacitor on the output side of the reverse current blocking circuit. A smoothing capacitor connected between the DC power supply line and the smoothing capacitor detects that the terminal voltage of the smoothing capacitor becomes below a predetermined level, and forms a signal to turn on the switch based on this detection. a voltage detection and switch control circuit configured to supply power to the switch and connected so that the smoothing capacitor acts as a power source to form the on-control signal; At this time, the compensating capacitor and the smoothing capacitor are charged through the rectifier and the reverse current blocking circuit, and power is supplied to the load, and after the voltage of the AC power source falls below the predetermined level. A DC power supply device configured to provide a voltage obtained by adding the voltage of the compensation capacitor to the output voltage of the rectifier to the load during a period in which the voltage of the AC power supply gradually increases to the predetermined voltage value.