JPH0965655A - DC power supply - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To suppress the weight increase, the size increase and the cost increase of a DC power supply device, and further to improve the power factor. SOLUTION: AC power input from an AC power supply 1 is full-wave rectified by a diode bridge 2, and a choke CH1, a capacitor C1, a transistor Q1 are supplied from a positive hot line.
Through the negative common line to charge the capacitor C1. The discharge current is diode D1, capacitor C
1, it is supplied to the load 3 via the choke CH2. The switching control circuit (SWCC) 5 has two chokes CH.
The voltage at the connection point A between 1 and CH2 is detected, and a drive signal for switching the transistor Q1 at high speed is output while the instantaneous value of the detected voltage is higher than the DC component voltage thereof, that is, during the charging cycle of the capacitor C1. Therefore, even if the inductance of the choke CH1 is small, it acts as a choke input type smoothing circuit to reduce ripples and widen the conduction angle, so that the peak current from the AC power source 1 is greatly reduced and the power factor is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply device for rectifying and smoothing input AC power to supply DC power to a load, and more particularly to a smoothing circuit of the DC power supply device.

[0002]

2. Description of the Related Art In order to convert input AC (alternating current) power into DC (direct current) power and supply it to a load, full-wave rectification is generally performed by a diode bridge. Therefore, the ripple is reduced or eliminated through the smoothing circuit after the rectification. As a smoothing circuit for that purpose, a capacitor input type and a choke input type are well known.

FIG. 14 is a circuit diagram showing an example of a capacitor input type rectifying and smoothing circuit, which is a commercial 50 Hz or 60 H.
The AC power input from the z AC power supply 31 is full-wave rectified by the diode bridge 32, and the DC power smoothed by the smoothing capacitor C4 is output to the load 33. FIG.
FIG. 4 is a waveform diagram showing an example of voltage or current of each part when the load 33 is non-inductive, for example, a resistive load.

FIGS. 15A and 15B are waveform diagrams of the voltage (current is also the same) on the input side and the output side of the diode bridge 32 when the smoothing capacitor C4 is not connected. The voltage (current) input to the load 33 has a large ripple as shown in FIG. As shown in FIG. 14, the smoothing capacitor C4
, The ripple between the terminals, that is, the ripple of the voltage (current) input to the load 33 is significantly reduced as shown in FIG.

[0005]

However, since the frequency of the AC power source 31 which is a commercial power source is low, the capacity of the smoothing capacitor C4 must be set large in order to reduce the ripple, but the smoothing capacitor C4 is charged. The current flows only when the instantaneous value of the full-wave rectification voltage shown in FIG. 15B exceeds the instantaneous value of the voltage across the smoothing capacitor C4 shown in FIG. 15C. , The conduction angle is narrow when viewed in phase. Therefore, the reactive power increases and the effective power decreases.

Since a large capacity capacitor has to be charged with a small conduction angle, as shown in the waveform diagram of the AC current on the input side shown in FIG. Since a large peak current, which is several times to more than ten times the average current value, flows, the power factor deteriorates, the life of the smoothing capacitor C4 is shortened, and high frequency noise occurs. Therefore, the instantaneous decrease in the power supply voltage of the AC power supply 31 and the high frequency noise adversely affect other devices connected to the same AC line.

Although not shown, the choke input type rectifying and smoothing circuit in which a choke coil is provided between the diode bridge 32 and the smoothing capacitor C4 shown in FIG. 14 has a lower output voltage with respect to the load than the capacitor input type. However, the inductive property of the choke coil and the decrease in the output voltage act in combination to widen the conduction angle, and the AC power supply 3
The peak current on the 1st side is reduced and the power factor is improved.

However, in this case as well, since the frequency of the AC power source 31 is low, the choke coil has an inductance of several mH or more (the smaller the required current value is, the larger it is) depending on the required current value of the load 33. Will be required. Therefore, there is a problem that the weight and size of the DC power supply device are increased and the cost is significantly increased.

The present invention has been made in view of the above points, and it is an object of the present invention to suppress the weight increase, the size increase, and the cost increase of a DC power supply device, and to improve the power factor.

[0010]

In order to achieve the above object, the present invention provides a diode bridge for full-wave rectifying AC input power in a DC power supply device for rectifying and smoothing AC input power to supply DC power to a load. And a positive and negative line connecting the output end of the diode bridge and the input end of the load as a common line and the other as a hot line for the common line, and first and second lines connected in series to the hot line. And a choke coil for each of them are provided as described below.

That is, the smoothing capacitor having one end connected to the connection point between the first choke coil and the second choke coil, and the smoothing capacitor connected between the other end of the smoothing capacitor and the common line are charged. For detecting the voltage at the connection point between the first choke coil and the second choke coil or at the input end on the hotline side of the load, and the parallel circuit of the switching element and the diode for discharging the load from the smoothing capacitor to the load. When the absolute value of the detected voltage is larger than the absolute value of the DC component voltage obtained by removing the ripple component from the detected voltage, a switching control circuit that outputs a drive signal for opening and closing the switching element to the switching element at high speed is provided. It is provided.

Alternatively, a smoothing capacitor connected between a connection point between the first choke coil and the second choke coil and a common line, and a switching element for charging the smoothing capacitor and a smoothing capacitor to a load. A series circuit including a parallel circuit with a diode for discharging, a connection point between the first choke coil and the second choke coil, an input end on the hot line side of the load, or a terminal on the hot line side of the smoothing capacitor. When any one of these voltages is detected and the absolute value of the detected voltage is larger than the absolute value of the DC component voltage, which is the detected voltage minus the ripple component, the drive signal for opening and closing the switching element at high speed is output. A switching control circuit for outputting, a primary coil for inputting a drive signal output by the switching control circuit, and a switching element It is provided with a driving transformer consisting of the connected secondary coils between motion signal input terminal.

Alternatively, a smoothing capacitor connected between a connection point between the first choke coil and the second choke coil and a common line, and a switching element for charging the smoothing capacitor and a smoothing capacitor to a load. A series circuit including a parallel circuit with a diode for discharging, a connection point between the first choke coil and the second choke coil, an input end on the hot line side of the load, or a terminal on the hot line side of the smoothing capacitor. When any one of these voltages is detected and the absolute value of the detected voltage is larger than the absolute value of the DC component voltage, which is the detected voltage minus the ripple component, the drive signal for opening and closing the switching element at high speed is output. A switching control circuit for outputting, a leak resistance connected between the drive signal input terminals of the switching element,
A CR coupling circuit including a coupling capacitor that connects one end of the leak resistance and the output terminal of the drive signal of the switching control circuit is provided.

In the above DC power supply device, the first and second choke coils are one choke coil having an intermediate tap from one end to the intermediate tap and from the intermediate tap to the other end. Middle tap first
It may be a connection point between the second choke coil and the second choke coil.

Alternatively, at least either of the positive and negative output terminals of the diode bridge, the positive and negative input terminals of the load, or the connection point between the first choke coil and the second choke coil and the common line. It is advisable to provide a small-capacity capacitor for bypassing high-frequency noise at one location. Furthermore, the load may be a constant voltage DC / DC converter.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. In the embodiments described below, a negative line is a common line, a positive line is a hot line, and a transistor is used as a switching element. FET (field effect transistor) or MO as a switching element
When using S-FET, the emitter of the transistor,
The base and collector can be read as source, gate, and drain, respectively.

FIG. 1 is a circuit diagram showing an example of the configuration of a first embodiment of a direct-current power supply device according to the present invention. A diode bridge 2 constituting a rectifying section and first and second sections constituting a smoothing section, respectively. It comprises choke coils CH1 and CH2 which are second choke coils, a smoothing capacitor C1, a parallel circuit 4 of a transistor Q1 and a diode D1, and a switching control circuit (SWCC) 5.

The diode bridge 2 full-wave rectifies the AC power input from the AC power supply 1 to convert it into DC power, and supplies it to the load 3 via the smoothing section. The negative output end of the diode bridge 2 and the negative input end of the load 3 are directly connected by a common line, and the hot line connecting the positive output end of the diode bridge 2 and the positive input end of the load 3 has a choke coil. CH1 and CH2 are connected in series.

Connection point A of choke coils CH1 and CH2
Is connected to the positive terminal of the smoothing capacitor C1, and the parallel circuit 4 of the transistor Q1 and the diode D1 is connected between the negative terminal and the common line. Parallel circuit 4
Is a smoothing capacitor C
Since a current flows in the direction in which 1 discharges, the emitter of the NPN transistor Q1 is connected to the common line, and the collector is connected to the negative terminal of the smoothing capacitor C1.
When the base is more positive than the common line, current flows in the direction of charging the smoothing capacitor C1.

The switching control circuit 5 whose common terminal is connected to the common line inputs the voltage at the connection point A of the choke coils CH1 and CH2 to its detection terminal, and detects the instantaneous value of the input detection voltage and its detection voltage. Further, by comparing with the voltage of the direct current component from which the ripple component obtained by smoothing is removed, only when the instantaneous value of the detected voltage is higher, for example, AC
Several KHz to several hundred KHz, which is much higher than the frequency of the power supply 1.
A positive drive signal having a frequency of
To open and close at high speed.

FIG. 2 is a waveform diagram showing an example of each instantaneous value of voltage and current in each part of the DC power supply device shown in FIG.
2A, 2B, and 2C are voltage waveform diagrams of the input side, output side, and connection point A of the diode bridge 2, that is, the positive terminal of the smoothing capacitor C1, respectively, and FIG. And (E) are waveform diagrams of the input side current of the diode bridge 2 and the charging current of the smoothing capacitor C1, respectively.

Vd indicated by broken lines in FIGS. 2B and 2C is the voltage of each DC component, and strictly speaking, there is a difference by the voltage drop due to the resistance component of the choke coil CH1, but Since the resistance value is small, it can be considered to be the same. ΔV shown in (C) of FIG. 2 is the ripple component p
-P value.

The charging current of the smoothing capacitor C1 flowing in the choke coil CH1 is A as shown in FIG.
Since it is switched at a frequency much higher than the frequency of the C power source 1 or twice the frequency thereof (by full-wave rectification), even if the inductance is a small value, it works sufficiently as a choke input type. Instead of the output voltage for the load 3 being slightly lowered, the conduction angle becomes wider as shown in (D) of the figure, and its peak current is greatly reduced.

That is, during the charging period in which the instantaneous value of the voltage at the connection point A is higher than the voltage across the common line of the smoothing capacitor C1, the current for charging the smoothing capacitor C1 via the choke coil CH1 is the frequency of the AC power source 1. Since the switching is performed at a much higher frequency, the inductance of the choke coil CH1 can be much smaller than that of the normal choke input type, and the size and weight can be reduced.

Further, the discharge current of the smoothing capacitor C1 is supplied to the load 3 via the choke coil CH2 and the diode D1. However, even if the choke coil CH1 is small and lightweight, its effect is great, and therefore the frequency of the AC power source 1 is 2%. The choke coil CH2, which is expected to have a choke effect for double the frequency, can also be made smaller and lighter. Therefore, both the choke coils CH1 and CH2 are reduced in size and weight, and the cost thereof can be significantly reduced.

The reason why the initial terminal of the switching control circuit 5 is connected to the hot line on the output side of the diode bridge 2 is to obtain the power from the power source at the initial stage when the power source is turned on. If it is input, the DC component voltage obtained by removing the ripple component from the detection voltage input to the detection terminal operates as the power supply.

Also, a small-capacity capacitor for high-frequency bypass, which is connected between the positive and negative output terminals of the diode bridge 2, between the positive and negative input terminals of the load 3, or between the connection point A and the common line as shown by the broken line. Cp should be provided in one or two places at least in the most effective place,
High-frequency noise due to the switching of the charging current according to the drive signal shown in FIG. 2E can be bypassed to prevent adverse effects on the AC power supply 1 and the load 3.

For example, as shown in FIG.
In the current of the C power source 1, high frequency noise due to switching of the charging current of the smoothing capacitor C1 by the transistor Q1 does not appear. The same applies to the current of the load 3 not shown.

FIG. 3 is a circuit diagram showing an example of the configuration of the second embodiment of the DC power supply device according to the present invention.
The difference from the first embodiment shown in FIG. 2 is that instead of detecting the voltage at the connection point A of the choke coils CH1 and CH2,
The voltage of the input end of the load 3 on the hot line side, that is, the positive input end is input as the detection voltage, and the same reference numerals are given to the other same portions and the description thereof will be omitted.

The voltage waveform at the positive input terminal of the load 3 has a ripple ΔV reduced by the amount of passing through the choke coil CH2 as compared with the voltage waveform at the connection point A shown in FIG. 2C. The operation of the switching control circuit 5 is exactly the same, and therefore the effect is also the same.

FIG. 4 is a circuit diagram showing an example of the configuration of the third embodiment of the DC power supply device. The points different from the first embodiment shown in FIG. 1 are the first and second embodiments. Instead of the choke coils CH1 and CH2, one choke coil CH3 having an intermediate tap B is connected in series to a hot line, and the other same parts are designated by the same reference numerals and their description is omitted. .

That is, the left side of the middle tap B of the choke coil CH3 corresponds to the first choke coil CH1, and the right side of the middle tap B corresponds to the second choke coil CH1.
The intermediate tap B corresponds to the connection point A of the first and second choke coils CH1 and CH2. A big difference in performance is that the left and right coils of the intermediate tap B are magnetically coupled to each other.

According to the result of experimentally constructing the circuit, when the one choke coil provided with the intermediate tap B and the two left and right coils are magnetically coupled is used, the load 3 is increased. The effect of reducing the ripple between the positive and negative input terminals of was excellent. In addition, the size of one choke coil is smaller than that of two choke coils.
It is needless to say that the weight is reduced and the cost is excellent, and the same effect can be obtained when applied to the second embodiment shown in FIG.

The first to third embodiments described with reference to FIGS. 1 and 3 and 4 are based on the invention described in claim 1, and are composed of a transistor Q1 and a diode D1 connected in parallel. The circuit 4 is connected to the common line side, the smoothing capacitor C1 is connected to the connection point A or the intermediate tap B on the hot line side, and the output terminal of the switching control circuit 5 and the base of the transistor Q1 are directly connected.

FIG. 5 is a circuit diagram showing an example of the configuration of the fourth embodiment of the DC power supply device. The difference from the first embodiment shown in FIG. 1 is that the output of the switching control circuit 5 is different. Instead of directly connecting the terminal and the base of the transistor Q1, a drive transformer 6 in which the primary coil and the secondary coil are galvanically isolated is provided, and a drive signal is transmitted through the transformer 6. .

That is, the primary coil of the drive transformer 6 is between the output terminal of the switching control circuit 5 and the common line, and the secondary coil thereof is between the input terminal of the switching element and the base-emitter of the transistor Q1. The base of the transistor Q1 is set to be positive with respect to its emitter when connected and the output terminal of the switching control circuit 5 is positive with respect to the common line. (There is no problem even if the polarity of the secondary coil is reversed.)

FIG. 6 is a circuit diagram showing an example of the configuration of the fifth embodiment of the DC power supply device. The difference from the fourth embodiment shown in FIG. 5 is that of the first embodiment. Similar to the third embodiment (FIG. 4) for (FIG. 1), one choke coil CH3 having an intermediate tap B is provided instead of the first and second choke coils CH1, CH2. Yes, others are the same as in the fourth embodiment.

Therefore, the operation and effect of the fourth and fifth embodiments shown in FIGS. 5 and 6 are exactly the same as those of the first and third embodiments (FIGS. 1 and 4), respectively. , Detailed description is omitted. Although not shown in the drawing, the switching control circuit 5 is also used in the fourth and fifth embodiments as in the second embodiment shown in FIG.
It goes without saying that the same operation and effect can be obtained even if the detection terminal of is connected to the input end of the load 3 on the hotline side.

However, without directly connecting the output terminal of the switching control circuit 5 and the base of the transistor Q1,
By providing the drive transformer 6 which insulates both of them from DC, the parallel circuit 4 including the transistor Q1 and the diode D1 is always provided on the common line side with respect to the smoothing capacitor C1, that is, the emitter of the transistor Q1 is provided. This has the effect of eliminating the need for direct connection to the common line.

FIG. 7 is a circuit diagram showing an example of the configuration of the sixth embodiment of the DC power supply device. The difference from the fourth embodiment shown in FIG. 5 is that the transistor Q1 and the diode D1 are By changing the arrangement order of the series circuit of the parallel circuit 4 and the smoothing capacitor C1, the negative terminal of the smoothing capacitor C1 is connected to the common line, and the positive terminal and the first and second choke coils CH1 and CH2 are connected. That is, the parallel circuit 4 is connected to the connection point A.

As shown in FIG. 7, even if the emitter of the transistor Q1 is separated from both the common line and the hot line and placed in the floating level state, the secondary of the drive transformer 6 is provided between the base and the emitter. If the coil is connected, the secondary coil is insulated from the primary coil in terms of direct current, so that there is no possibility of causing troubles such as destruction of the transistor Q1 and normal operation is achieved.

Although not shown in the drawing, in the sixth embodiment as well, the detection terminal of the switching control circuit 5 is connected to the input end of the load 3 on the hotline side, as in the second embodiment (FIG. 3). There is no problem even if it is connected to and the voltage is detected.

FIG. 8 is a circuit diagram showing an example of the configuration of the seventh embodiment of the DC power supply device. The difference from the sixth embodiment shown in FIG. 7 is the detection of the switching control circuit 5. The terminals are connected to the first and second choke coils CH1 and CH2.
Instead of connecting to the connection point A, the smoothing capacitor C1 is connected to the positive terminal and the voltage between the terminals is detected.

In the seventh embodiment shown in FIG. 8, the instantaneous value of the detected voltage is slightly different from the instantaneous value of the voltage at the connection point A, but the discharge current remains when the charging current flows through the smoothing capacitor C1. Even when flowing, the voltage drop due to the transistor Q1 or the diode D1 is slight, and
The voltage (for example, 100V) at which the C power is full-wave rectified by the diode bridge 2 to charge the smoothing capacitor C1.
It can be neglected compared to ~ 140V).

As described above, the fourth example shown and described with reference to FIGS.
The seventh to seventh embodiments are according to the invention described in claim 2, respectively, and the drive signal output from the switching control circuit 5 is transmitted to the transistor Q1 which is a switching element via the drive transformer 6. In addition, in the sixth and seventh embodiments (FIGS. 7 and 8),
Similar to the fifth embodiment (FIG. 6), the first and second choke coils CH1 and CH2 are provided with an intermediate tap B1.
It can be replaced with an individual choke coil CH3.

FIG. 9 is a circuit diagram showing an example of the configuration of the eighth embodiment of the DC power supply device. The difference from the fourth embodiment shown in FIG. 5 is that the primary coil and the secondary coil are different. A CR coupling circuit including a capacitor C2, which is a coupling capacitor whose input side and output side are also galvanically insulated, and a resistor R1, which is a leak resistance, instead of the drive transformer 6 whose coil is galvanically insulated. 7 is provided and the drive signal output from the switching control circuit 5 is transmitted to the transistor Q1 via the coupling circuit 7.

That is, as shown in FIG. 9, the transistor Q1 between the drive signal input terminals of the switching element is
Resistor R1 is connected between the base and emitter of
A capacitor C2 for blocking direct current is connected between the base side terminal of the switching control circuit 5 and the output terminal of the switching control circuit 5, and the time constant which is the product of the capacitance value of the capacitor C2 and the resistance value of the resistor R1 It is set to be larger than the reciprocal (cycle) of the frequency.

Therefore, its operation and effect are exactly the same as those of the drive transformer 6 used in the fourth embodiment (FIG. 5). Also, in the ninth to eleventh embodiments shown in FIGS. 10 to 12, respectively, the drive transformer 6 in the fifth to seventh embodiments shown in FIGS. 6 to 8 is replaced with a CR coupling circuit 7. Therefore, like the eighth embodiment (FIG. 9), the operation and effect are exactly the same, and the same portions are denoted by the same reference numerals and description thereof is omitted.

The eighth to eleventh embodiments described with reference to FIGS. 9 to 12 are according to the invention described in claim 3, and the drive signal output from the switching control circuit 5 is CR-coupled. The signal is transmitted to the transistor Q1 which is a switching element via the circuit 7. In addition, the tenth and eleventh embodiments (FIGS. 11 and 1)
Also in 2), the first and second choke coils CH
1, CH2 can be replaced by a single choke coil CH3 with an intermediate tap B.

The first to eleventh embodiments described above, and the respective modified circuits (not shown) are two or one.
The choke coil is used to increase the conduction angle compared to the capacitor input type and has the characteristic of the choke input type that suppresses the peak current from the AC power source 1, while switching the charging current of the smoothing capacitor C1 at high speed. By doing so, the inductance of the choke coil is reduced, and the features are that it is small, lightweight and inexpensive.

However, in the DC power output from these DC power supply devices, although the ripple component is reduced or removed, the output voltage with respect to the input voltage fluctuation of the AC power supply 1 and the fluctuation of the current flowing through the load 3 are input. Has no constant voltage property. In addition, the common line and the hot line connected to the load 3 have an AC grounded on either side to the ground.
Since it is completely floating with respect to the power source 1, there is a risk of electric shock even if any line is touched.

Therefore, if the load 3 is a lighting lamp or the like in a TV studio, a stage for TV relay, a stadium, etc., in which only flicker due to a commercial frequency is a problem,
Since the constant voltage property is hardly a problem and there is no fear of electric shock,
The effect of reducing the ripple by using a choke coil having a relatively small capacity and the capacity of the smoothing capacitor being small in response to the demand for the large power is extremely large. Thus, although effective for some limited applications,
As it is, it is dangerous to use it for many general applications, and it is not suitable for applications requiring constant voltage.

However, if a DC / DC converter having a constant voltage characteristic is connected as the load, there is no problem in terms of the constant voltage characteristic, and in particular, the input side and the output side are insulated from each other. , For example, if you connect a switching regulator, there is no danger of electric shock.

FIG. 13 is a circuit diagram showing an example of the configuration of a switching regulator which is a constant voltage DC / DC converter whose input and output sides to be combined as the load 3 are insulated from each other. Since the operation and effect of the switching regulator shown in FIG. 13 are well known,
Briefly explained.

DC input to the positive and negative terminals of the input side Vin
The electric power is a transistor (or FE) which is a switching element connected in series with the primary coil Np of the transformer 10.
T) Turned on and off at high speed by Q2. Transformer 1
The AC power induced in the secondary coil Ns of 0 is rectifier diode D2, commutation diode D3, choke coil CH.
4, converted into DC power rectified and smoothed by the rectification smoothing circuit 11 composed of the smoothing capacitor C3, and output Vou
It is output from the positive and negative terminals of t.

The control circuit 12 which outputs the drive pulse to the transistor Q2 detects the voltage Vout of the DC power to be output, and raises the on-duty ratio of the drive pulse if it is lower than the preset output voltage, and if it is higher than the preset output voltage. By lowering, the control is performed so that the set output voltage is maintained even if the input voltage or the output current fluctuates.

Such a DC / DC converter is connected as the load 3, that is, the DC power supply device according to the present invention is connected to D
By using as a DC power source in combination with a C / DC converter and outputting the constant voltage DC power output by the DC / DC converter to a target device or apparatus, it is possible to safely handle a wide range of applications. .

In the above-described embodiments, the negative line is the common line and the positive line is the hot line. However, conversely, the positive line is the common line and the negative line is the hot line. Even in this case, it goes without saying that the present invention can be applied in exactly the same manner if the polarities of the smoothing capacitor C1 and the diode D1 and the direction of the current flowing in the transistor Q1 are reversed.

[0059]

As described above, the DC power supply device according to the present invention is small and lightweight, has a low cost, and has an improved power factor.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an example of a first embodiment of a DC power supply device according to the present invention.

FIG. 2 is a waveform diagram showing an example of voltage or current of each part of the DC power supply device shown in FIG.

FIG. 3 is a circuit diagram showing an example of a second embodiment of a DC power supply device according to the present invention.

FIG. 4 is a circuit diagram showing an example of a third embodiment of a DC power supply device.

FIG. 5 is a circuit diagram showing an example of a fourth embodiment of a DC power supply device.

FIG. 6 is a circuit diagram showing an example of a fifth embodiment of a DC power supply device.

FIG. 7 is a circuit diagram showing an example of a sixth embodiment of a DC power supply device.

FIG. 8 is a circuit diagram showing an example of a seventh embodiment of a DC power supply device.

FIG. 9 is a circuit diagram showing an example of an eighth embodiment of a DC power supply device.

FIG. 10 is a circuit diagram showing an example of a ninth embodiment of a DC power supply device.

FIG. 11 is a circuit diagram showing an example of a tenth embodiment of a DC power supply device.

FIG. 12 is a circuit diagram showing an example of an eleventh embodiment of a DC power supply device.

FIG. 13: DC connected to a DC power supply device according to the present invention
It is a circuit diagram which shows an example of a / DC converter.

FIG. 14 is a circuit diagram showing a conventional capacitor-input type rectifying and smoothing circuit.

15 is a waveform diagram showing an example of voltage or current in each part of the rectifying / smoothing circuit shown in FIG.

[Explanation of symbols]

 1: AC power supply 2: Diode bridge 3: Load 4: Parallel circuit 5: Switching control circuit 6: Drive transformer 7: CR coupling circuit A: Connection point B: Intermediate tap C1: Smoothing capacitor C2: Capacitor (coupling capacitor) Cp: Small-capacity capacitor CH1: first choke coil CH2: second choke coil CH3: choke coil with intermediate tap D1: diode Q1: transistor (switching element) R1: resistance (leakage resistance)

Claims (6)

[Claims] 1. A DC power supply device for rectifying and smoothing AC input power to supply DC power to a load, comprising: a diode bridge for full-wave rectifying the AC input power; an output end of the diode bridge and an input end of the load. First and second choke coils connected in series to the hot line, with one of the positive and negative lines connecting to and as a common line and the other as a hot line for the common line. And a smoothing capacitor having one end connected to a connection point of the second choke coil, a switching element connected between the other end of the smoothing capacitor and the common line for charging the smoothing capacitor, and the smoothing capacitor. A parallel circuit with a diode for discharging the load to the load, the first choke coil and the second choke When the voltage at the connection point with the coil or the input end on the hotline side of the load is detected, and the absolute value of the detected voltage is greater than the absolute value of the voltage of the direct current component obtained by removing the ripple component from the detected voltage,
A DC power supply device comprising: a switching control circuit that outputs a drive signal for opening and closing the switching element at high speed to the switching element. 2. A DC power supply device for rectifying and smoothing AC input power to supply DC power to a load, comprising: a diode bridge for full-wave rectifying the AC input power; an output end of the diode bridge and an input end of the load. First and second choke coils connected in series to the hot line, with one of the positive and negative lines connecting to and as a common line and the other as a hot line for the common line. A smoothing capacitor, a switching element for charging the smoothing capacitor, and a diode for discharging the smoothing capacitor to the load, the smoothing capacitor being connected between the connection point of the second choke coil and the common line. A series circuit including a parallel circuit; a connection point between the first choke coil and the second choke coil; The voltage at any one of the input end on the hot line side of the load or the terminal on the hot line side of the smoothing capacitor is detected, and the absolute value of the detected voltage is the DC component excluding the ripple component from the detected voltage. A switching control circuit that outputs a drive signal for opening and closing the switching element at high speed when the voltage is greater than the absolute value of the voltage, a primary coil that inputs the drive signal output by the switching control circuit, and a drive for the switching element. A DC power supply device comprising a drive transformer including a secondary coil connected between signal input terminals. 3. A DC power supply device for rectifying and smoothing AC input power to supply DC power to a load, a diode bridge for full-wave rectifying the AC input power, an output end of the diode bridge, and an input end of the load. First and second choke coils connected in series to the hot line, with one of the positive and negative lines connecting to and as a common line and the other as a hot line for the common line. A smoothing capacitor, a switching element for charging the smoothing capacitor, and a diode for discharging the smoothing capacitor to the load, the smoothing capacitor being connected between the connection point of the second choke coil and the common line. A series circuit including a parallel circuit; a connection point between the first choke coil and the second choke coil; The voltage at any one of the input end on the hot line side of the load or the terminal on the hot line side of the smoothing capacitor is detected, and the absolute value of the detected voltage is the DC component excluding the ripple component from the detected voltage. A switching control circuit that outputs a drive signal for opening and closing the switching element at high speed when the absolute value of the voltage is larger than the absolute value of the voltage; a leak resistance connected between drive signal input terminals of the switching element; A DC power supply device comprising: a CR coupling circuit including a coupling capacitor that connects one end to an output end of a drive signal of the switching control circuit. 4. The DC power supply device according to claim 1, wherein the first and second choke coils are provided from one end of one choke coil having an intermediate tap to the intermediate tap. And the intermediate tap to the other end, and the intermediate tap of the choke coil serves as a connection point between the first choke coil and the second choke coil. 5. The DC power supply device according to claim 1, wherein the diode bridge has positive and negative output terminals, a positive and negative input terminals of the load, or the first choke coil. Second
2. A DC power supply device, characterized in that a small-capacity capacitor for bypassing high-frequency noise is provided in at least one of the connection point with the choke coil and the common line. 6. The DC power supply device according to claim 1, wherein the load is a constant voltage DC / DC converter.