JP3740926B2 - Power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply apparatus that uses a rectification method using a bridge rectifier circuit and supplies power to an apparatus, a system, or the like.
[0002]
[Prior art]
Conventionally, various rectification methods using diodes are known. FIG. 8 shows an example of a full-wave rectifier circuit using a bridge rectifier circuit. The full-wave rectifier circuit shown in this figure includes a bridge rectifier circuit 5 composed of four diodes 1 to 4 and a smoothing capacitor 8 at the stage after rectification. Reference numeral 14 denotes a load.
[0003]
FIG. 8A shows the flow of current during the half cycle in which the AC from the AC power source 6 is positive. Since the current flows in the order of the diode 1, the smoothing capacitor 8, and the diode 4 as indicated by the arrows, a positive voltage Vo can be taken out.
[0004]
FIG. 8B shows a current flow during a half cycle in which the AC from the AC power source 6 is negative. Since the current flows in the order of the diode 3, the smoothing capacitor 8, and the diode 2 as indicated by the arrows, a positive voltage Vo can be taken out. That is,
The AC input from the AC power supply 6 is full-wave rectified to obtain a positive DC voltage.
[0005]
[Problems to be solved by the invention]
However, the conventional power supply apparatus as described above has a problem in that the input current flows only during a period in which the voltage of the AC power supply 6 is higher than the DC output voltage, so that the power factor is low and the power supply harmonics are large.
[0006]
Normally, a method of connecting a reactor between the AC power source 6 and the bridge rectifier circuit 5 is used as an improvement measure. However, this method can obtain a power factor of only about 70% even if harmonics can be suppressed. Therefore, there is a problem in that a medium-capacity to large-capacity power supply increases the size of elements constituting the power supply, which in turn increases the size of the device, and places a burden on the power supply system.
[0007]
The power supply device of the present invention solves the above-described conventional problems, and by connecting a capacitor between the AC input terminal and the DC output terminal of the bridge rectifier circuit, high power factor and harmonic suppression are achieved. An object of the present invention is to provide a power supply device capable of satisfying both requirements.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a power supply apparatus according to the present invention includes an AC power supply, a bridge rectifier circuit formed by four diodes for full-wave rectification of AC from the AC power supply, and a DC output of the bridge rectifier circuit. A current device having a smoothing capacitor connected to an end, the reactor connected between the AC power source and the AC input end of the bridge rectifier circuit, the AC input end and the DC output end of the bridge rectifier circuit And a switching device connected in series with the capacitor, and a diode in which the AC power supply side is connected as a cathode and the DC output end side is connected as an anode in parallel with the switching device. An opening / closing control circuit for opening / closing the opening / closing means; and an AC power source opening phase detection circuit between the AC power supply and the AC input terminal of the bridge rectifier circuit, and the opening / closing means by the opening / closing control circuit for opening / closing the opening / closing means. A power supply apparatus, which is performed in synchronism with a signal from a mouth opening phase detection means.
[0009]
According to the power supply device as described above, even when the alternating current from the alternating current power source is in either the positive half cycle or the negative half cycle, the current can be supplied from the zero phase of the alternating voltage, and the power factor can be increased. be able to. In addition, since the current becomes a series resonance current between the reactor and the capacitor or the smoothing capacitor, the waveform is smooth and harmonics can be suppressed.
[0010]
Furthermore, inrush current can be prevented by closing the switching means at the zero phase of the power supply voltage.
[0011]
A current device having an AC power supply, a bridge rectifier circuit formed of four diodes for full-wave rectification of AC from the AC power supply, and a smoothing capacitor connected to a DC output terminal of the bridge rectifier circuit; A reactor connected between the AC power source and the AC input terminal of the bridge rectifier circuit; a capacitor between the AC input terminal and the DC output terminal of the bridge rectifier circuit; And an opening / closing means, comprising a diode connected in parallel with the opening / closing means as a cathode on the AC power source side and an anode on the DC output end side, and the reactor is saturated in a region of a constant current value or more. .
[0012]
According to the power supply device as described above, it is possible to prevent a decrease in the DC output voltage in a region where the load current is large.
[0013]
And a current device having an AC power source, a bridge rectifier circuit formed of four diodes for full-wave rectification of AC from the AC power source, and a smoothing capacitor connected to a DC output terminal of the bridge rectifier circuit. A reactor connected between the AC power source and the AC input terminal of the bridge rectifier circuit, a capacitor between the AC input terminal and the DC output terminal of the bridge rectifier circuit, and a cathode in series with the capacitor. A diode connected to the thyristor, connected in parallel with the thyristor, connected to the AC power supply side as a cathode and connected to the DC output end side as an anode, and has a current detection on the negative side of the DC output end Means for opening and closing the thyristor by this output.
[0014]
According to the power supply device as described above, since charging of the capacitor can be stopped at a light load, an increase in output voltage more than necessary can be suppressed. Further, the current detecting means and the opening / closing means can be easily configured with a small number of parts.
[0015]
In addition, a diode is connected in parallel with the current detection means with the bridge rectifier circuit side as a cathode. According to the power supply apparatus as described above, it is possible to reduce the power loss in the current detection means and realize a more efficient power supply apparatus.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Components having the same configurations as those of the conventional example will be described with the same numbers.
[0017]
Example 1
FIG. 1 shows a circuit diagram of a power supply apparatus according to Embodiment 1 of the present invention.
[0018]
A bridge rectifier circuit 5 formed by an AC power source 6, four diodes 1 to 4 for full-wave rectification of the AC from the AC power source 6, and a smoothing capacitor 8 is connected to the DC output terminal of the bridge rectifier circuit 5. The smoothing capacitor 8 can convert the direct current of drastic change obtained by the bridge rectifier circuit 5 into a smooth direct current. A reactor 7 is connected between the AC power source 6 and the AC input terminal of the bridge rectifier circuit 5. A capacitor 9 and an opening / closing means 11 are connected in series with the capacitor 9 between the AC input terminal and the DC output terminal of the bridge rectifier circuit 5. In parallel with the opening / closing means 11, a charging stop diode 10 is connected so that the AC power supply side is a cathode and the DC output end side is an anode. An open / close control circuit 13 for opening / closing the open / close means 11 is provided, and an AC power supply phase detector 12 is provided between the AC power supply 6 and the AC input terminal of the bridge rectifier circuit 5. The opening / closing means 11 is opened / closed by the opening / closing control circuit 13 in synchronization with the signal from the AC power source opening phase detection circuit 12.
[0019]
Hereinafter, the operation of the power supply device shown in FIG. 1 will be described with reference to FIGS. 2A, 2B, 2C, and 2D. 2A and 2B show the AC input voltage Vi during the positive half cycle, and FIGS. 2C and 2D show the negative half cycle.
[0020]
In the following description, the opening / closing means 11 is in a closed state.
[0021]
In the state shown in FIG. 2A, that is, immediately after the zero phase of the positive AC half cycle, the current flows in the direction of arrow a. That is, in order from the AC power supply 6, the resonance current flows through the capacitor 9, the diode 4, and the reactor 7, and the capacitor 9 is charged. As the capacitor 9 is charged, the voltage Vc continues to rise.
[0022]
FIG. 2B shows the current flow after Vc rises to Vo. In this state, since Vc is clamped to Vo, the current flows in the order of the diode 1, the smoothing capacitor 8, the diode 4, and the reactor 7 in this order from the AC power source 6, as indicated by the arrow b.
[0023]
FIG. 2C shows a state in which the polarity of the AC power source 6 is reversed from the states of FIGS. 2A and 2B. In this state, current flows in the order of the reactor 7, the diode 3, the smoothing capacitor 8, and the capacitor 9 in this order from the AC power supply 6 as indicated by the arrow c. That is, since the potential of the AC power supply 6 is boosted by the voltage Vc of the capacitor 9, a current always flows through the smoothing capacitor 8 from the zero phase. Due to the current flow shown in the figure, the capacitor 9 continues to be discharged and finally Vc becomes zero.
[0024]
FIG. 2D shows a state after the completion of the discharge of the capacitor 9. In the state shown in this figure, as indicated by the arrow d, the current flows in order from the AC power source 6 in the order of the reactor 7, the diode 3, the smoothing capacitor 8, and the diode 2, and the voltage Vc of the capacitor 9 becomes Vc = 0. Clamped.
[0025]
When the polarity of the AC power supply 6 is reversed after finishing the negative AC half cycle, the current flows again in the direction of arrow a as shown in FIG. 2A because it is clamped at Vc = 0.
[0026]
As described above, in the state shown in FIGS. 2A and 2B, the capacitor 9 is charged until Vc = Vo, so that current starts to flow from the zero phase of the input voltage. In the state shown in FIG. 2 (c), the potential of the AC power supply 6 is boosted by the voltage Vc of the capacitor 9, so that current flows from the zero phase. That is, in the case where the alternating current from the alternating current power supply 6 is in either a positive half cycle or a negative half cycle, the current flows from the zero phase of the alternating current power supply, and a high power factor can be achieved.
[0027]
Further, since the current is a series resonance current between the reactor 7 and the capacitor 9 or the smoothing capacitor 8, a smooth sine waveform is obtained. By appropriately selecting the inductance L of the reactor 7 and the capacitance C of the capacitor 9, the harmonic current is obtained. Can be suppressed appropriately. The above is the basic operation description of the circuit.
[0028]
Next, the charging stop diode 10, the switching means 11, and the zero phase detection circuit 12 will be described.
[0029]
In the state shown in FIG. 2C, the potential of the AC power supply 6 is boosted by the voltage Vc of the capacitor 9, so that when the load is lighter than the charging energy of the capacitor 9, a phenomenon in which the output voltage increases excessively occurs. Therefore, by adding a charging prevention diode 10 and switching means 11 in series with the capacitor 9 as shown in the figure, in the case of a light load, the switching means can be opened while leaving a discharge circuit using the charging prevention diode 10. By opening (cutting), charging of the capacitor 9 is stopped, and an increase in output voltage is suppressed. By adding the diode 10 for preventing charging, even when the opening / closing means 11 is opened to stop the charging of the capacitor 9, a path for discharging the charging voltage of the capacitor 9 at that time can be left.
[0030]
When the operation is started, the initial voltage of the capacitor 9 is zero. Therefore, by using the detection signal of the zero phase detection circuit 12, the switching means is closed (ON) in synchronization with the zero phase of the AC power supply voltage. To do. As a result, an inrush current generated by a circuit formed by the capacitor 9, the bridge rectifier circuit 5, and the reactor 7 can be prevented. That is, an excessive current to the opening / closing means 11 can be prevented.
[0031]
Here, the circuit configuration will be supplemented based on FIG.
Although the circuit operation has been described based on FIG. 3A, the capacitor 9, the charge stopping diode 10, and the opening / closing means 11 have the same configuration as shown in FIGS. 3B, 3C, and 3D. The effect is obtained.
[0032]
(Example 2)
FIG. 4 shows a circuit diagram of a power supply apparatus according to Embodiment 2 of the present invention.
[0033]
A bridge rectifier circuit 5 formed by an AC power source 6, four diodes 1 to 4 for full-wave rectification of the AC from the AC power source 6, and a smoothing capacitor 8 is connected to the DC output terminal of the bridge rectifier circuit 5. A reactor 7 is connected between the AC power source 6 and the AC input terminal of the bridge rectifier circuit 5. A capacitor 9 and an opening / closing means 11 are connected in series with the capacitor 9 between the AC input terminal and the DC output terminal of the bridge rectifier circuit 5. In parallel with the opening / closing means 11, a charging stop diode 10 is connected so that the AC power supply side is a cathode and the DC output end side is an anode.
[0034]
FIG. 5 shows the characteristics of the reactor 7 according to the second embodiment.
In the reactor, the relationship between the current value IL (AC effective value) and the voltage VL (AC voltage) changes linearly in the unsaturated region. However, when the reactor enters the saturation region, it loses the actance characteristics and increases the voltage VL relative to the current IL. Becomes nonlinear. Using this characteristic, the reactor 7 is set to saturate in the large current region Io or more, thereby reducing the voltage drop due to the reactor in the region where the output current becomes large and suppressing the DC voltage output value from being lowered. Can do.
[0035]
Since the basic operation of the circuit is the same as that of the first embodiment, description thereof is omitted.
[0036]
Example 3
FIG. 6 shows a circuit diagram of a power supply device according to Embodiment 3 of the present invention.
[0037]
A bridge rectifier circuit 5 formed by an AC power source 6, four diodes 1 to 4 for full-wave rectification of the AC from the AC power source 6, and a smoothing capacitor 8 is connected to the DC output terminal of the bridge rectifier circuit 5. The reactor 7 is connected between the AC power source 6 and the AC input terminal of the bridge rectifier circuit 5. A capacitor 9 and a thyristor 15 as an opening / closing means are connected in series between the AC input terminal and the DC output terminal of the bridge rectifier circuit 5. In parallel with the Siris evening 12, a charging stop diode 10 is connected so that the AC power supply side is a cathode and the DC output end side is an anode. A current detection resistor 16 is provided on the negative side of the DC output terminal, and the thyristor 15 is opened and closed by applying a gate voltage to the thyristor 15 by the output voltage generated by the voltage drop.
[0038]
In the region where the load becomes lighter, the voltage drop value at the current detection resistor 16 also becomes smaller in proportion to the load. Thereby, the thyristor can be opened (turned off) in a light load region by utilizing the lack of the gate voltage for closing (turning on) the thyristor. As a result, the charging of the capacitor 9 is stopped in the light load region to suppress an increase in the DC output voltage.
[0039]
Further, by realizing the roles of the charging stop diode 10 and the thyristor 12 together with a reverse conducting thyristor, the number of parts can be further reduced.
[0040]
(Example 4)
FIG. 7 shows a circuit diagram of a power supply device according to Embodiment 4 of the present invention.
[0041]
A bypass diode 17 is connected in parallel with the current detection resistor 16 with the bridge rectifier circuit side as a cathode. As a result, the voltage signal necessary for closing (turning on) the thyristor 15 can be suppressed to VF of the bypass diode 17. Therefore, while securing a voltage signal for closing (turning on) the thyristor 15, it is possible to reduce loss due to heat generation in the current detection resistor 16 and suppress power loss more than necessary.
[0042]
【The invention's effect】
As described above, according to the power supply device of the present invention, the inrush current to the switching means can be prevented by detecting the zero phase of the AC power supply and closing the switching means. For this reason, since the component which comprises an opening-and-closing means does not require high current capacity, cost reduction and size reduction are attained.
[0043]
Further, by saturating the reactor characteristics in a large current region where the load is high, a voltage drop due to the reactor can be reduced, and a decrease in the DC output voltage can be avoided.
By maintaining the DC output voltage, the load resistance of the entire system can be increased.
[0044]
Further, by using a thyristor as the opening / closing means, the charging / discharging circuit by the capacitor can be automatically opened / closed according to the load, so that the number of parts can be reduced and the configuration of the power supply circuit can be simplified.
[0045]
Further, by adding a diode in parallel with the current detection resistor, a heat loss due to a voltage drop in the current detection resistor can be reduced, and a more efficient circuit can be configured.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a power supply device according to a first embodiment of the present invention. FIG. 2 is an operation explanatory diagram according to the first embodiment of the present invention. FIG. 3 is another circuit configuration diagram according to the first embodiment of the present invention. 4 is a circuit diagram of a power supply device according to Embodiment 2 of the present invention. FIG. 5 is a reactor characteristic diagram according to Embodiment 2 of the present invention. FIG. 6 is a circuit diagram of a power supply device according to Embodiment 3 of the present invention. FIG. 7 is a circuit diagram of a power supply device according to a fourth embodiment of the present invention. FIG. 8 is a circuit diagram of a conventional power supply device.
1, 2, 3, 4 Diode 5 Bridge rectifier circuit 6 AC power source 7 Reactor 8 Smoothing capacitor 9 Capacitor 10 Charging stop diode 11 Open / close means 12 Zero phase detection circuit 13 Open / close control circuit 14 Load 15 Thyristor 16 Current detection resistor 17 Bypass diode

Claims (5)

A power supply apparatus comprising: an AC power supply; a bridge rectifier circuit formed of four diodes that rectifies the AC from the AC power supply in full wave; and a smoothing capacitor connected to a DC output terminal of the bridge rectifier circuit. A reactor connected between the AC power source and the AC input terminal of the bridge rectifier circuit, a capacitor between the AC input terminal and one DC output terminal of the bridge rectifier circuit, and a capacitor And a switching device connected in series with the switching device, and a diode connected in parallel with the switching device, the AC power supply side being a cathode and the DC output end side being an anode. And closing control circuit for opening and closing the opening and closing means comprises an AC power zero port phase detection circuit between the AC input of the AC power supply and the bridge rectifier circuit, before Ki交 the opening and closing of the closing means by the switching control circuit 2. The power supply apparatus according to claim 1, wherein the power supply apparatus is performed in synchronization with a signal from a current power source opening phase detection circuit.   2. The power supply device according to claim 1, wherein the reactor is magnetically saturated in a region having a constant current value or more. An AC power source, a power supply device including a bridge rectifier circuit formed by four diodes for full-wave rectifying an AC and a connected smoothing capacitor to the DC output end of the bridge rectifier circuit from the AC power source A reactor connected between the AC power source and the AC input end of the bridge rectifier circuit; a capacitor between the AC input end and the DC output end of the bridge rectifier circuit; and a cathode in series with the capacitor. A diode connected to the thyristor, connected in parallel to the thyristor, connected to the AC power supply side as a cathode and connected to the DC output end as an anode, and having a current detection means on the negative side of the DC output end And a power supply device that opens and closes the thyristor according to the output.   5. The power supply device according to claim 4, wherein a diode is connected in parallel with the current detection means with the bridge rectifier circuit side as a cathode.

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