JPH0984354A - Switching power-supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a compact configuration, light weight at low cost and to improve the power conversion efficiency and the like in a switching power supply circuit. SOLUTION: For current resonance type switching converters 100A, 100B and 100C, the following parts are provided in parallel with a commercial AC power supply AC. A filter choke coil is inserted into the output line of a bridge rectifier circuit D1 A. Power-factor improving circuits 10A, 10B and 10C feed back the switching output to the rectifier output line for the connecting point of the choke coil and a high-speed recovery diode D2 through a primary-side resonance circuit (C1 , N1 ) and improve the power factor. These parts are connected to the respective converters 100A, 100B and 100C in this improved-power- factor power supply circuit part. Thus, the switching power supply circuit is constituted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current resonance type switching power supply circuit for improving power factor, for example.

[0002]

2. Description of the Related Art In recent years, as a power supply device for rectifying a commercial power supply to obtain a desired DC voltage by developing a switching element capable of withstanding a relatively large current and voltage of a high frequency, a switching type power supply is mostly used. It is a device. The switching power supply is used as a power supply for various electronic devices as a high power DC-DC converter while increasing the switching frequency to reduce the size of a transformer and other devices.

In general, when a commercial power supply is rectified, the current flowing through the smoothing circuit has a distorted waveform, which causes a problem that the power factor indicating the efficiency of use of the power supply is impaired. Further, there is a need for a measure for suppressing harmonics generated due to the distorted current waveform.

Therefore, as a power factor improving means for improving the power factor in the power supply circuit, there is known a method of providing a so-called active filter in which a switching converter is provided in the rectifier circuit system to bring the power factor close to 1. Since this active filter operates independently, it can be applied, for example, when the power supply circuit is under heavy load or when simultaneously improving the power factor for a plurality of switching converters.

FIG. 13 is a circuit diagram showing an example of a switching power supply circuit including the active filter and configured to improve the power factor. The power supply circuit shown in this figure has, for example, an AC input voltage of 100 V AC system or AC
It is a so-called single range compatible with either one of the 200V systems. In addition, the stabilized DC output voltage on the secondary side is set to 2 channels or more, the load power is 250 W or more in the AC input voltage AC100V system, and the AC input voltage AC2.
The 00V system is configured to handle a heavy load of 500 W or more. Further, as a switching converter for obtaining a stabilized DC output voltage on the secondary side from a rectified output, a self-excited current resonance type converter in which switching elements are half-bridge coupled is used.

In the switching power supply circuit shown in FIG. 13, a common mode choke coil CMC and an across capacitor C _L are provided as a noise filter for removing common mode noise with respect to the commercial AC power supply AC. Further, two sets of normal mode low-pass filters formed by the filter choke coil L _N and the filter capacitor C _N are provided for the commercial AC power supply AC. The common-mode and normal-mode noise filters prevent high-frequency noise such as switching noise from flowing into the line of the commercial AC power supply AC.

The commercial AC power supply AC is a bridge rectifier circuit D ₁
Is full-wave rectified by. In this case, the rectification output terminal of the bridge rectification circuit D ₁ and the smoothing capacitors Ci ₁ , Ci
The winding Li of the choke coil CH and the fast recovery diode D ₂ are connected in series between the positive terminals of ₂ and Ci ₃ (rectified output line).

The winding Li of the choke coil CH is
As an inductance that functions as an energy storage means for becoming a voltage source or a current source at a level higher than the rectified and smoothed voltage in order to flow a current to the load side (switching converter section side) during the switching period of the switching element Q ₂₁ described later. Has been inserted. Further, the high speed recovery type diode D ₂ corresponds to a high frequency current flowing through the rectified output line by the switching operation of the switching element Q ₂₁ as described later.

The rectified current flowing through the rectified output line via the winding Li of the choke coil CH and the high speed recovery type diode D ₂ is smoothing capacitors Ci ₁ , Ci ₂ and C.
The smoothing capacitors Ci ₁ and Ci _{2 are} charged and discharged by i _3.
, Across the Ci _3, rectified and smoothed voltage as a operating power of the subsequent switching converter portion 200A~200C is obtained. In this case, for example, the smoothing capacitors Ci ₁ , Ci ₂ , and Ci are provided so that a plurality of switching converter units provided in the subsequent stage can obtain the corresponding current capacity.
₃ are provided in parallel. Further, as the smoothing capacitors Ci ₁ , Ci ₂ , Ci ₃ in this case, for example, electrolytic capacitors of 470 μF / 400 V are selected.

Further, in this case, the switching element Q _21, which is a component forming the active filter, uses, for example, a MOS-FET transistor, the drain of which is the winding Li of the choke coil CH and the fast recovery type diode D. _It is connected to the connection point of the _second anode, and the source is provided so as to be grounded to the primary side ground via the inrush current limiting resistor R _D. The switching element Q _21, by switching the drive signal is supplied to the gate from the drive circuit of the active filter control circuit 10 which will be described later, the switching operation is performed. Note that the winding Li of the choke coil CH, in order to flow current into the load side (switching converter section side) during the switching period of the switching element Q ₂₁ described later,
It is inserted as an inductance that functions as an energy storage means for becoming a voltage source or a current source having a level higher than the rectified and smoothed voltage. Further, the high speed recovery type diode D ₂ corresponds to a high frequency current flowing through the rectified output line by the switching operation of the switching element Q ₂₁ as described later.

In this case, the active filter control circuit 10 controls the operation of the active filter for improving the power factor so that the power factor approaches 1 and is, for example, a one-stone integrated circuit (IC). . In this case, the active filter control circuit 10 includes a starting circuit that drives the switching element Q ₂₁ when the power is turned on, an oscillation circuit that generates a required switching frequency, and an amplification circuit that amplifies the signal of the oscillation frequency to drive the switching element Q _21. A drive circuit that generates a gate signal, and P that performs PWM control for the switching drive signal output from the drive circuit
It is composed of a WM control circuit, a multiplier for performing multiplication based on inputs of a feedforward circuit and a feedback circuit described below, and a control input signal of the PWM control circuit, and the like. In this case, commercial AC power supply A
Rectifier diodes D _6A and D _6B are provided for both poles of C to form a double-wave rectifier circuit, and the output of this double-wave rectifier circuit is divided by resistors R ₁ and R ₂ to the active filter control circuit 10. Input, which forms a feedforward circuit for the AC input voltage. In addition, the feedback circuit includes smoothing capacitors Ci ₁ and Ci.
_The voltage across both ends of ₂ and Ci ₃ (rectified and smoothed voltage) is applied to resistors R ₃ and R ₃ .
It is formed by inputting the voltage value divided by ₄ to the active filter control circuit 10. That is, to the active filter control circuit 10 shown in this figure, the voltage value corresponding to the level of the AC input voltage is input from the feedforward circuit, and the voltage value corresponding to the rectified and smoothed voltage level is input from the feedback circuit. Will be done.

The positive output of the bridge rectifier circuit is input to the active filter control circuit 10 as a power source for start-up, and a half of the coil N ₅ wound around the choke coil CH and the rectifier diode D ₅ is used. The output of the wave rectifier circuit is supplied as the operating power supply of the active filter control circuit 10.

The outline of the power factor improving operation by the active filter configured as described above is as follows. For example, the active filter control circuit 10 detects the AC input voltage level based on the voltage value input from the feedforward circuit and inputs it to the internal multiplier.
On the other hand, the difference in fluctuation of the rectified and smoothed voltage is detected based on the voltage value input from the feedback circuit, and the difference in fluctuation of the rectified and smoothed voltage is input to the internal multiplier. Then, the multiplier multiplies the variation difference between the AC input voltage level and the rectified and smoothed voltage, and the result of this multiplication produces, for example, a current command value having the same waveform as the _AC input voltage VAC. Then, the PWM control circuit compares the current command value with the actual AC input current level, generates a PWM signal corresponding to the difference, and supplies the PWM signal to the drive circuit. The switching element Q ₂₁ is switching-driven by the drive signal based on this PWM signal. As a result, the AC input current is controlled so as to have the same waveform as the AC input voltage, and the power factor approaches 1 so that the power factor is improved. Further, in this case, since the current command value generated by the multiplier is controlled so that the amplitude changes according to the difference in fluctuation of the rectified and smoothed voltage, the fluctuation of the rectified and smoothed voltage is also suppressed. .

In this power supply circuit, in order to cope with the heavy load condition as described above, the smoothing capacitor Ci
A plurality of switching converter units using the rectified and smoothed voltage obtained by ₁ , Ci ₂ , and Ci ₃ as an operating power source are provided in parallel. In this figure, three switching converter units 200A, 200B, and 200C are provided, and the secondary side DC output voltages E _O1 , E _O2 , and E _O3 stabilized to a predetermined level can be output respectively. .

For example, the switching converter section 200
The configuration of A is provided with _two switching elements Q ₁ and Q _{2 which} are half-bridge coupled as shown in the figure, and are respectively connected between the positive terminal of the smoothing capacitors Ci ₁ , Ci ₂ and Ci ₃ and the primary side ground. Is connected via the collector and emitter. The collectors of the switching elements Q _1, Q ₂ - is between the base, each starting resistor R _S, R
_S is inserted, and the base current (drive current) of the switching elements Q ₁ and Q ₂ is adjusted by the resistors R _B and R _B.
Further, the bases of the switching elements Q _1, Q ₂ - each damper diode between the emitter D _D, D _D is inserted. The resonance capacitors C _B and C _B form a series resonance circuit for self-excited oscillation together with the drive windings N _B and N _{B of} the drive transformer PRT described next.

Drive transformer PRT (Power Regulati
ng Transformer) variably controls the switching frequency of the switching elements Q ₁ and Q ₂ , and in the case of this figure, the drive windings N _B and N _B and the resonance current detection winding N _D are wound. control winding N _C is the orthogonal saturable reactor is wound in a direction orthogonal to the windings. _One end of the drive winding N _B on the switching element Q ₁ side of the drive transformer PRT has a resonance capacitor C _B.
To the resistor R _B , and the other end is connected to the emitter of the switching element Q ₁ . Further, one end is grounded to the primary side ground drive winding N _B of the switching element Q ₂ side, the other end a drive winding N _B of is connected to the resonance capacitor C _B switching element Q ₁ side opposite The voltage of the polarity is output.

Isolation Converter Transformer PIT (Power Is
(Olation Transformer) transmits the switching outputs of the switching elements Q ₁ and Q _{2 to} the secondary side. One end of the primary winding N ₁ of this insulating converter transformer PIT has a contact point between the emitter of the switching element Q _{1 and} the collector of the switching element Q ₂ (through a series connection of a series resonance capacitor C ₁ and a resonance current detection winding N _D ). It is connected to the switching output point) and the other end is grounded to the primary side ground so that the switching output is obtained. The inductance component of the insulating converter transformer PIT including the series resonance capacitor C ₁ and the primary winding N ₁ forms a series resonance circuit for making the switching power supply circuit a current resonance type. Note that, hereinafter, this series resonance circuit will be particularly referred to as a primary side series resonance circuit.
In the case of this switching power supply circuit, on the secondary side of the insulating converter transformer PIT, the alternating voltage obtained by the switching operation on the primary winding N ₁ is compared with the secondary winding N ₂ whose center tap is grounded to the secondary side ground. The excited voltage is converted into a DC voltage by a double-wave rectification circuit composed of rectifying diodes D _3A and D _3B and a smoothing capacitor C ₃ , and an output voltage E ₀₁ is obtained.

The control circuit 1 is, for example, an error amplifier which compares the DC voltage output E _O1 on the secondary side with a reference voltage and supplies a DC current corresponding to the error to the control winding N _C of the drive transformer PRT.

In the switching operation of the switching power supply having the above structure, when a commercial AC power supply is first turned on, for example, the switching element Q is turned on via the starting resistors R _S and R _{S.
Although the} base current is supplied to the bases of ₁ and Q ₂ , if the switching element Q ₁ is turned on _first , the switching element Q ₂ is controlled to be turned off. Then, as an output of the switching element Q ₁ , a resonance current flows through the resonance current detection winding N _D → the primary winding N ₁ → the series resonance capacitor C ₁ , but the switching element Q ₂ is turned on in the vicinity where the resonance current becomes zero. , The switching element Q ₁ is controlled to be turned off. The reverse resonant current flows from the preceding through the switching element Q _2. Thereafter, a self-excited switching operation in which the switching elements Q ₁ and Q ₂ are turned on alternately is started. Thus, smoothing capacitors Smoothing capacitors Ci ₁ , Ci ₂ , C
Switching element Q using the terminal voltage of i ₃ as the operating power supply
_By alternately opening and closing ₁ and Q ₂ , a drive current close to the resonance current waveform is supplied to the primary winding N ₁ of the insulating converter transformer PIT, and the secondary winding N ₂ on the secondary side is supplied.
Get the alternating output to.

Further, when the secondary side DC output voltage E _O1 decreases, the control circuit 1 controls the current flowing through the control winding N _C so that the switching frequency becomes low (close to the resonance frequency). Is controlled so that the drive current flowing through the primary winding N ₁ is increased to achieve a constant voltage. Note that such a constant voltage control method will be hereinafter referred to as a switching frequency control method.

The switching converter section 200
Since B and 200C have the same configurations as those of the switching converter unit 200A described above, the same parts as those of the switching converter unit 200A are denoted by the same reference numerals and description thereof will be omitted.

14 and 15 show the waveform of the switching power supply circuit AC input current I _AC shown in FIG. 13 together with the AC input voltage V _AC . For example, FIG.
Shows an operation waveform when the load power P _O = 600 W when the power supply circuit of 1 corresponds to the _AC input voltage V _AC = 230 V. As shown in FIG. 14A, when an AC input voltage of 230V _AC is input, the AC input current I _AC is as shown in FIG.
As shown in FIG. 4 (b), a sine wave similar to the waveform of the AC input voltage is used, and a power factor of about 0.97 is actually obtained. As the level of the _AC input current I _AC , I _AC =
4.2 Arms is obtained and the input power is 694 W. The power supply circuit of FIG. 13 has an AC input voltage V _AC = 10.
As the operation waveform when the load power P _O = 600 W corresponding to 0 V, for example, as shown in FIG.
When the AC input voltage of 00V is input, the AC input current I _AC = 8.8 Arms, and its waveform becomes a sine wave as shown in FIG.
It is assumed that a power factor of about 9 can be obtained. The input power at this time is 709W.

16A and 16B are perspective views showing structural examples of the filter choke coil L _N and the choke coil CH used in the switching power supply circuit of FIG. The filter choke coil L _N is, for example, as shown in FIG.
As shown in (a), a winding L as a single wire coil is wound around a toroidal core made of a magnetic material such as an amorphous or pressure powder iron core. FIG.
Similarly, the choke coil CH shown in (b) is configured by winding a winding Li (and a winding N ₅ ) by a single wire coil on a toroidal core made of an amorphous material, a pressure powder iron core, or the like. When the sizes of the filter choke coil L _N and the choke coil CH are compared, for example, as shown in FIG.
As can be seen from 6 (a) and 6 (b), the choke coil CH has a larger core size than the filter choke coil L _N.

[0024]

From the viewpoint of the size and cost of the equipment, it is possible to reduce the number of parts in the switching power supply circuit as much as possible and use small or inexpensive parts to reduce the size / size. It is preferable to reduce the weight and cost. In addition, it is preferable to improve electric characteristics such as power conversion efficiency.

For example, in the case of the power supply circuit shown in FIG.
The low-pass filter of the normal mode formed by the component group forming the active filter and the filter choke coil L _N and the filter capacitor C _N becomes large in response to the increase in load power, and in particular, it is shown in FIG. Filter choke coil L _N and choke coil C
H becomes large in size / weight in order to reduce saturation due to rush current at power-on and leakage magnetic flux at rated operation, which makes the cost expensive. Further, in the active filter shown in FIG. 13, since the switching element Q ₂₁ and the high speed recovery type diode diode D ₂ generate a high level harmonic current at the time of turn-on / off, the filter choke coil L _N and It is necessary to provide a so-called π-type normal mode filter in which two sets of normal mode low-pass filters are coupled by the filter capacitor C _N. Further, it is known that the power loss due to the provision of the active filter having the configuration shown in FIG. 13 is relatively large. For example, the switching element Q ₂₁ ,
It is necessary to select a large-capacity semiconductor such as the bridge rectifier circuit D ₁ and the high-speed recovery type diode diode D _2, and it is also necessary to provide a heat dissipation plate for reducing heat generation due to power loss in these parts. .

[0026]

In order to solve the above-mentioned problems, the present invention inputs the rectified and smoothed voltage obtained by rectifying and smoothing the commercial power source and performs switching drive to output the secondary side DC output voltage. Current resonance type switching converter and a power factor correction circuit for feeding back the switching output of the current resonance type switching converter to the rectified output line to improve the power factor. The switching power supply circuit is configured by providing the rate improvement converter unit in parallel with the commercial power supply.

The power factor correction circuit includes a filter choke coil and a high speed recovery type diode which are provided in series with the path of the rectified current, and a filter capacitor which forms a low pass filter together with the filter choke coil. The primary winding of the insulation transformer of the primary side series resonance circuit of the switching converter is formed so as to be connected to the connection point of the filter choke coil and the high speed recovery type diode via the series resonance capacitor.

Alternatively, the power factor correction circuit includes a filter choke coil, a high speed recovery type diode and a choke coil winding, which are provided in series with respect to the path of the rectified current.
A primary side series resonance circuit of a current resonance type switching converter is formed by connecting a filter capacitor forming a low pass filter together with a filter choke coil to a connection point between a high speed recovery type diode and a choke coil winding. I decided.

Alternatively, the power factor correction circuit includes a magnetic coupling transformer formed by magnetically coupling the first winding and the second winding, and a filter choke coil and a high speed recovery type are provided for the path of the rectified current. The diode and the first winding are inserted in series, the second winding is connected in series to the primary side series resonance circuit of the current resonance type switching converter, and a filter capacitor forming a low pass filter together with the filter choke coil is connected. It was decided to be prepared.

Further, in the power factor correction circuit, the rectifier circuit is configured as a voltage doubler rectifier circuit, or a rectifier circuit capable of automatically switching between a bridge rectifier circuit and a voltage doubler rectifier circuit according to the voltage value of the AC input voltage. The rectification current path of such a rectification circuit is applied as described above to improve the power factor by feeding back the switching output through the primary side series resonance circuit of the current resonance type switching converter as described above. I decided.

According to the above configuration, for example, in a switching power supply circuit in which a plurality of switching converters are provided in parallel with a commercial AC power supply to cope with a heavy load, a circuit simpler than that using an active filter. The power factor correction circuit formed by the configuration can improve the power factor. As a result, the number of parts such as switching elements of the active filter that easily cause power loss is also reduced.

[0032]

FIG. 1 is a circuit diagram showing the configuration of a switching power supply circuit as an embodiment of the present invention. In this case, a single range of an AC input voltage AC100V system or AC200V system Power is 250W-6
It is supposed to support heavy load of about 00W, but especially A
It is suitable for application to a power supply circuit compatible with the C200V system. The same parts as those of the power supply circuit shown in FIG. 13 shown as the conventional example are designated by the same reference numerals and the description thereof will be omitted.

In the power supply circuit shown in this figure, the common mode choke coil CMC is used for the commercial AC power supply AC.
And an across capacitor _CL are provided to form a common mode noise filter.

In this case, the bridge rectifier circuits D _1A , D _1B and D _1C are provided in parallel with the commercial AC power source AC as shown in the figure, and the commercial AC power source is supplied by the bridge rectifier circuits D _1A , D _1B and D _1C. It is designed to perform full-wave rectification of AC. Then, the rectified output of the bridge rectifier circuit D _1A is charged in the smoothing capacitor Ci ₁ via the power factor correction circuit 10A described later. Then, the switching converter unit 100A operates using the voltage across the smoothing capacitor Ci ₁ (rectified and smoothed voltage) as the operating power source, and the DC output voltage E _O1 is obtained. Further, the rectified output of the bridge rectifier circuit D _1B is the power factor correction circuit 1
The smoothing capacitor Ci ₂ is charged via 0B, and the switching converter unit 100B operates by the voltage across the smoothing capacitor Ci ₂ to obtain the DC output voltage E _O2 . Similarly, the rectified output of the bridge rectifier circuit D _1C is passed through the power factor correction circuit 10C to the smoothing capacitor C.
i ₃ is charged, the switching converter unit 100C is operated by using the voltage across the smoothing capacitor Ci ₃ as the operating power supply, and thereby the DC output voltage E _O3 is obtained. Thus, in the power supply circuit shown in FIG. E _O1 , E _O2 ,
It is possible to obtain a stabilized secondary side DC voltage of three channels of E _O3 .

That is, in the power supply circuit of the present embodiment, a bridge rectifier circuit and a power factor correction circuit are provided corresponding to a plurality of switching converter units, and the [bridge rectifier circuit- Power factor correction circuit-switching converter section] is connected in parallel and configured. In addition, in this figure, the power supply circuit section including the above [bridge rectifier circuit-power factor correction circuit-switching converter section] is 3
Although a pair is provided, as is apparent from the fact that the commercial power supply lines branching in parallel are extended by arrows in this figure, more power supply circuit units may be provided. Alternatively, there may be two sets.

In the power supply circuit of this embodiment, the switching converter units 100A, 100B, 1
00C uses a current resonance type converter.
The switching converter unit 100 shown in this figure
Similar to the switching converter units 200A, 200B, and 200C shown in FIG. 13, A, 100B, and 100C are self-exciting current resonance type converters in which switching elements are half-bridge coupled, and a converter drive is a constant voltage control system. Since the switching frequency control method by the transformer PRT is adopted, the same reference numerals as those in FIG. 13 are given and the description thereof is omitted.
Further, regarding the switching converter units 100B and 100C, the circuit configuration is not shown in detail, but is shown as a block. For example, the switching converter units 100A, 100B, 100C shown in the present embodiment
Is configured so that the load power of each DC output voltage E _O1 , E _O2 , and E _O3 can correspond to 200 W, and therefore a switching power supply circuit that can support a total load power of 200 W × 3 = 600 W is configured. To be done.

Next, the power factor correction circuit provided in the power supply circuit of this embodiment will be described. For example, the power factor correction circuit 10A provided on the rectification output line of the bridge rectification circuit D _1A corresponding to the switching converter unit 100A
Is formed by including a filter choke coil L _NA , a filter capacitor C _NA , a fast recovery type diode D ₂ , and a resonance capacitor C ₂ as shown in the figure. In this case, the filter choke coil L _NA and the fast recovery type diode D ₂ are provided in series with the rectified output line as shown in the figure. Further, the filter capacitor C _NA is inserted between the positive electrode output terminal of the bridge rectifier circuit D _{1A and} the positive electrode of the smoothing capacitor Ci ₁ so as to form a normal mode low pass filter together with the filter choke coil L _NA . The resonance capacitor C ₂ is inserted in parallel with the fast recovery type diode D ₂ as shown in the figure, and the filter choke coil L is connected by this connection form.
It is designed to form a resonant circuit with _NA . In this case, the end of the primary winding N ₁ of the insulating converter transformer PIT of the switching converter unit 100A using the current resonance type converter is connected to the filter choke coil L _NA and the high speed recovery type diode D via the series resonance capacitor C _1. Connected to ₂ connection points.

In the power factor correction circuit 10 formed by the connection configuration as described above, the switching converter section 100 is used.
The primary winding N _{1 of the} insulating converter transformer PIT forming the primary side series resonance circuit by the switching operation of AS.
The switching output obtained at
Filter choke coil L via ₁ capacitive coupling
It will be fed back to the connection point between the _NA and the fast recovery type diode D ₂ . The switching output fed back in this way causes the filter choke coil L _NA as a load to superimpose an alternating voltage of the switching cycle on the rectified output line, whereby the fast recovery diode D ₂ switches the rectified output current to the switching cycle. The switching operation is intermittently performed.

Therefore, the full-wave rectified voltage rectified by the bridge rectifier circuit D _1A is superposed with the switching voltage to charge the smoothing capacitor Ci _A. Then, the terminal voltage of the smoothing capacitor Ci _A is lowered in the switching cycle by the superposition of the switching voltage. Then, the charging current starts flowing while the terminal voltage of the smoothing capacitor Ci _A is lower than the rectified voltage level of the bridge rectifier circuit D _1A . And
In this case, the average waveform of the input current I ₁ input from the commercial AC power supply AC to the bridge rectifier circuit D _1A approaches the voltage waveform of the commercial AC power supply AC. That is, the conduction angle of the input current I ₁ is expanded.

Further, the switching converter section 100B
The configuration of the power factor correction circuit 10B provided corresponding to the above and the configuration of the power factor correction circuit 10C provided corresponding to the switching converter unit 100C are the same as the above-described power factor improvement 10A, so that The same reference numerals are given and the description is omitted. Therefore, the power factor correction operation is performed in the same manner as the power factor correction 10A described above, so that the input current I ₂ of the bridge rectifier circuit D _1B and the bridge rectifier circuit D
The conduction angle of the input current I ₃ of _1C is also expanded to the same extent as the input current I ₁ of the bridge rectifier circuit D _1A .

For example, FIG. 2 is a waveform diagram showing an AC input voltage, an input current, and KYD in the power supply circuit of this embodiment. For example, as shown in FIG. 2A, the AC input voltage V _AC Is supplied, the above-mentioned input currents I ₁ , I ₂ , and I ₃ are as shown in FIG. 2 (b) (c) (d), respectively.
Flow as shown in FIG.
The conduction angle is expanded by the action of B and 10C. In the case of the power supply circuit of FIG. 1, since the AC input current I _AC is obtained by combining the input currents I ₁ , I ₂ , and I ₃ , the waveform of the _AC input current I _AC is as shown in FIG. Actually, it has a conduction angle similar to that of the input currents I ₁ , I ₂ and I ₃ . In this way, control is performed so that the conduction angle of the waveform of the _AC input current I _AC is expanded, and as a result, the power factor is improved. In the power supply circuit of this embodiment, it is actually necessary to obtain a power factor of, for example, about 0.8 under the predetermined AC input voltage and load conditions to improve the power factor. The parts are selected, and it is possible to deal with the harmonic distortion regulation in a European region with a sufficient margin.

Further, the power factor correction circuit 10A as described above,
In the power supply circuit that improves the power factor based on the configurations of 10B and 10C, the switching frequency on the switching converter section (100A, 100B, 100C) side is controlled to increase as the load becomes lighter.
Although the drive current of the insulating converter transformer PIT becomes small, this drive current also makes the switching current flowing through the full-wave rectification output line small. Therefore, the average charging current level becomes small when the load is light and the charging current becomes large when the load is heavy. Therefore, the phenomenon that the terminal voltage of the smoothing capacitor abnormally rises especially when the load is light is eliminated, and the normal MS (magnet) is eliminated. -It is possible to improve the regulation, which was difficult with the power factor correction method by the switch method.

The power factor correction circuits 10A, 10
In B and 10C, a normal mode low-pass filter (filter choke coil L _NA and filter capacitor C _NA ) is provided on the rectification output side of the bridge rectification circuit D ₁ . According to such a connection form, the filter choke coil L _N and the fast recovery type diode D ₂ are connected in series and inserted in the rectified output line. However, by combining the resistance components of these elements. By setting the obtained value to a value that can suppress the inrush current when the power is turned on to a required level, it becomes possible to omit the inrush current limiting resistor that should normally be inserted in the AC line, Moreover, since the power consumption is dispersed by the resistance component of each element, heat generation can be suppressed.

Then, one end of the filter capacitor C _NA is not directly grounded to the ground, but the smoothing capacitor C _NA is
Although it is connected to the positive electrode of i ₁ , the voltage applied across the filter capacitor C _NA can be lower than when the normal mode low-pass filter is inserted on the AC line side. There is no need to select a pressure resistant product.

Further, each power factor correction circuit 10A, 10B, 1
At 0C, the parallel resonant circuit including the resonant capacitor C ₂ connected to the filter choke coil L _N is
Its resonance impedance is designed to change in response to load fluctuations, and when the load on this switching power supply becomes lighter, it suppresses the switching voltage fed back to the rectifying and smoothing line. It is possible to suppress the rise of the terminal voltage of the smoothing capacitor.

Further, in the configuration of the active filter provided in the power supply circuit of FIG. 13 shown as the prior art example, for example, 450 V / 20 A is selected for the switching element Q _21, and 600 V / for the fast recovery type diode D _2. 20
A and 600 V / 10 A were selected for each of the four rectifying diodes of the bridge rectifying circuit D ₁ . On the other hand, the power factor correction of the power supply circuit of FIG.
In A, 10B and 10C, switching element Q ₂₁
Not provided, also, those high-speed recovery type diode D ₂ are current capacity 10A, the bridge rectifier D _1A, D
_1B, may be selected to current capacity 5A in four rectifying diodes D _1C. Accordingly, in the present embodiment, for example, the bridge rectifier circuit, the fast recovery type diode D ₂ and the switching element Q, which are required in the circuit of FIG.
A heat sink for ₂₁ etc. is unnecessary.

Further, in the power supply circuit of FIG. 13, the choke coil CH of a large toroidal core as shown in FIG.
And the filter choke coil L _N were provided,
In the circuit of FIG. 1, the choke coil CH is omitted and the filter choke coil L _NA is small. FIG. 12 is a perspective view showing an example of the structure of the filter choke coil L _NA used in the power supply circuit of this embodiment. As shown in FIG. Can be configured as a lead inductor.

The power supply circuit of FIG. 1 is configured by the components selected as described above, so that the power loss is reduced and the power conversion efficiency is improved. For example, the power conversion efficiency eta _AC → _DC power supply circuit specifically shown in FIG. 13, the AC input voltage V _AC = 230V Sometimes, eta _AC
→ _DC = (power conversion efficiency of active filter x power conversion efficiency of switching converter section) = 92% x 94% ≈
The power conversion efficiency was 86.5%, which was about 3.5% lower than the power conversion efficiency of 90% in the configuration of the power supply circuit before the power factor improvement without the active filter. On the contrary,
In the power supply circuit of FIG. 1, the actual AC input current I _AC is 4.8.
Although the effective current increases due to Arms, the power conversion efficiency is 91%, and the power conversion efficiency before power factor improvement is 90%.
1%, and the input power of the power supply circuit of FIG. 13 is 694 W, whereas it is 659 W in the power supply circuit of FIG. The result is achieved.

From the above, although the power supply circuit of the present embodiment is provided with the bridge rectification circuit and the power factor correction circuit corresponding to the number of switching converter units, FIG.
When compared with the power supply circuit shown in FIG. 3, it is possible to achieve a smaller size / lighter weight and lower cost, and it is also advantageous in terms of characteristics such as power conversion efficiency.

FIG. 3 is a circuit diagram showing the configuration of the embodiment of the switching power supply circuit of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.
In the case of the power supply circuit shown in this figure, _one bridge rectifier circuit D ₁ for rectifying the commercial AC power supply AC is common,
Power factor correction circuits 11A, 11B, and 11C are provided in parallel with the rectified output of the bridge rectification circuit D ₁ as shown in the drawing, and switching is performed for the respective subsequent stages of these power factor correction circuits 11A, 11B, and 11C. Converter unit 101
A, 101B, 101C are provided. Then, the switching converter units 101A, 10
The stabilized secondary side DC output voltages E _O1 , E _O2 , and E _O3 are obtained from each of 1B and 101C. That is, in this case, the power supply circuit section formed by the [power factor correction circuit-switching converter section] is connected in parallel to the common bridge rectifier circuit D ₁ . By doing so, it is not necessary to provide a plurality of bridge rectifier circuits according to the number of switching converter units provided in parallel as in the power supply circuit of FIG. 1, so that the number of components can be reduced accordingly. Become. However, in this case, since the current capacity of the bridge rectifier circuit D ₁ increases, for example, a heat sink is provided for the bridge rectifier circuit D _{1 on} the actual power supply circuit board surface.

Further, the configuration of the power factor correction circuit 11A shown in FIG. 3 is such that the filter choke coil L _NA , the high speed recovery type diode are connected to the rectification output line between the bridge rectification circuit D ₁ and the positive terminal of the smoothing capacitor Ci _1. D ₂ and the winding Li _A of the choke coil CH are connected in series. The filter capacitor C _NA in this case is inserted between the connection point of the filter choke coil L _NA and the fast recovery diode D ₂ and the positive terminal of the smoothing capacitor Ci ₁ , and together with the filter choke coil L _NA , a normal mode low-pass filter. I am trying to form a filter.
In this case, the resonance capacitor C ₂ is connected in parallel to the winding Li _A of the choke coil CH to form a parallel resonance circuit.
In the same manner as in the case of ₁ , the operation of suppressing the voltage across the smoothing capacitor Ci ₁ from rising is obtained when the load becomes light, for example. The choke coil CH in this case is configured as a small choke coil in which a litz wire is wound around an EI type core made of a ferrite material or the like having a size of about EI-23 type.

In this case, the insulating converter transformer PRT of the switching converter unit 101A in the subsequent stage is also used.
The primary winding N ₁ of via a series resonance capacitor C _1,
Fast recovery type diode D ₂ in power factor correction 11A
And the connection point of the winding Li _A of the choke coil CH. That is, in this case, the switching output supplied to the primary side series resonance circuit of the switching converter unit 101A is fed back by being superimposed on the rectified output line side by the magnetic coupling of the choke coil CH. ing. In the power factor correction circuit having such a configuration, the switching voltage is superimposed with the inductance of the winding Li _A of the choke coil CH as a load, and the switching of the fast recovery type diode D ₂ is promoted by the superimposed switching voltage. It will work. Even in this case, the same operation as that of the power factor correction circuit of the power supply circuit of FIG.

Switching converter sections 101A, 10
Power factor correction circuit 11 provided corresponding to each 1B
Since B and 11C have the same configuration as the power factor correction circuit 11A described above, the same parts as those of the power factor correction circuit 11A are denoted by the same reference numerals, and the description of the configuration will be omitted. Therefore, the power factor correction circuits 11B and 11C operate to expand the conduction angle of the AC input current to the same extent as in the power factor correction circuit 11A. In this way, the power factor correction circuits 11A, 11B, and 11C expand the conduction angle of the AC input current flowing to the commercial AC power supply AC, and as a result, the AC input current as shown in FIG. I _AC is obtained, and its waveform approaches the AC input voltage to improve the power factor.

Further, the switching converter section 101
A, 101B, 101C are switching elements Q ₁ , Q
_{Since 2} is a half-bridge coupled self-exciting current resonance type converter, the same parts as those of the switching converter 100A of FIG. In addition, the switching converter units 101B, 1
Since 01C has the same configuration as that of the switching converter unit 101A, the specific circuit configuration is not shown in the figure, and is shown as a block.

In the switching converter unit 101A of this embodiment, the converter drive transformer CD
T has a structure in which the control winding N _C is not wound as in the case of FIG. 1, and therefore the switching frequency is fixed.
In this case, in the insulating converter transformer PRT, the control winding N _C is provided so that the winding directions of the primary winding N ₁ and the secondary winding N ₂ are orthogonal to each other. In this case, the control circuit 1 supplies the control current to the control winding N _C as the control current, which is a DC current of a level that is varied according to the variation of the DC output voltage E _O1. In the PRT, the leakage magnetic flux is changed to change the inductance of the primary winding N ₁ . Due to this inductance change, the resonance frequency of the primary side series resonance circuit is variably controlled with respect to the switching frequency, whereby the secondary side DC output voltage E _O1 can be made a constant voltage. Hereinafter, such constant voltage control will be referred to as a series resonance frequency control method. The switching converter unit 101
Similarly, in B and 101C, the secondary side DC output voltages E _O2 and E _O3 are respectively controlled by the series resonance frequency control method.
Will be made constant voltage.

Even with the power supply circuit having such a configuration, when compared with the power supply circuit of FIG. 13, for example, the circuit size can be made smaller and lighter as described in the power supply circuit of FIG. The power conversion efficiency will also be improved.

FIG. 4 is a circuit diagram showing the configuration of a switching power supply circuit according to still another embodiment of the present invention.
The same parts as those of the power supply circuit shown in FIGS. 1 and 3 are designated by the same reference numerals and the description thereof is omitted. First, the switching converter unit used in the power supply circuit of the present embodiment will be described. In the present embodiment, two switching converter units 102A and 102B are provided in parallel with the rectified output as shown in the figure, but in reality, more switching converter units may be provided. . Further, since the switching converter unit 102A and the switching converter unit 102B are configured as a separately excited current resonance type converter of the same type as will be described later, the same reference numerals are given to the same portions and the description thereof will be omitted.

Switching converter section 1 shown in this figure
02A includes switching elements Q ₁₁ and Q ₁₂ such as MOS.
-It is a separately excited current resonance type converter using a half bridge connection using FET. In this case, the control circuit 1 controls the oscillation drive circuit 2 based on the DC output voltage E _O1.
To control the switching element Q from the oscillation drive circuit 2.
Constant voltage control is performed by changing the switching drive voltage supplied to the gates of ₁₁ and Q ₁₂ (for example, performing variable pulse width control of the drive voltage). D _D and D _D connected between the drains and sources of the switching elements Q ₁₁ and Q _{12 in} the direction shown in the figure are the paths of the current fed back when the switching elements Q ₁₁ and Q ₁₂ are off. It is a damper diode to be formed. Further, the starting circuit 3 is provided to detect the voltage or current obtained in the rectifying and smoothing line at the time of starting the power source to start the oscillation drive circuit 2. The starting circuit 3 is provided in the insulating converter transformer PIT. The low-voltage DC voltage generated by the tertiary winding N ₃ , the rectifying diode D _4, and the smoothing capacitor C ₄ is supplied.

Further, the switching converter section 102B
Is a separately excited type current resonance type converter by half bridge connection similar to the above-mentioned switching converter unit 102A, and outputs a DC output voltage E _O2 which has been made into a constant voltage. In addition, in the starting circuit 3 of the switching converter unit 102B, the switching converter unit 102 described above is used.
The low-voltage DC voltage obtained by the tertiary winding N ₃ , the rectifying diode D _4, and the smoothing capacitor C ₄ of the insulating converter transformer PIT of A is input as the power source for starting. Since the field effect type switching element used in this embodiment is driven by voltage and self-excited oscillation becomes difficult, it is preferable to provide the oscillation drive circuit 2 and the starting circuit 3 as shown in this figure.

In the case of the power supply circuit shown in FIG. 4, the filter choke coil L _N and the filter capacitor C _N are connected to the rectified output line of the bridge rectifier circuit D ₁ as shown in the figure.
Normal mode low-pass filter LP formed by
F is provided. Then, in the subsequent stage of the normal mode low-pass filter LPF, the power factor improving circuit 12A is provided corresponding to the switching converter unit 102A, and the power factor improving circuit 12B is provided in the switching converter unit 1.
It is provided corresponding to 02B. For example, in the power supply circuits of FIGS. 1 and 3 described above as the embodiments, the normal mode low-pass filter including the filter choke coil L _NA and the filter capacitor C _NA is provided in each power factor correction circuit. On the other hand, in the present embodiment, the bridge rectifier circuit D ₁ −normal mode low-pass filter LP
The circuit portion of F is commonly provided for the parallel connection of the power supply circuit section including the power factor correction circuit and the switching converter section in the subsequent stage.

Next, the power factor correction circuit of this embodiment will be described. In this figure, two power factor correction circuits 12A, 1
Although 2B is shown, since both have the same configuration, the same portions are denoted by the same reference numerals and description thereof will be omitted. For example, the power factor correction circuit 12A provided corresponding to the switching converter unit 102A includes a fast recovery type diode D ₂ , a magnetic coupling transformer MCT, and a resonance capacitor C ₂ as shown in the figure. The magnetic coupling transformer MCT is configured by winding the primary winding L _P and the secondary winding Li _{A such} that they are magnetically tightly coupled to each other. In this power factor correction circuit 12A, the bridge rectifier circuit D
_For the rectified output line from ₁ to the smoothing capacitor Ci ₁ on the side of the switching converter 102A, the secondary of the fast recovery diode D ₂ and the magnetic coupling transformer MCT is passed through the filter choke coil L _NA of the normal mode low pass filter LPF. Winding Li _A is inserted in series. The resonance capacitor C _{2 in} this case is connected in parallel to the secondary winding Li _A of the magnetic coupling transformer MCT to form a parallel resonance circuit. The primary winding L _P of the magnetic coupled transformer MCT is provided so as to connect in series with the primary side series resonant circuit of the switching converter portion 102A. That is, in this case, one end of the primary winding L _P of the magnetic coupling transformer MCT is connected to the primary winding N ₁ of the insulating converter transformer PIT, and the other end is connected to the primary side ground via the series resonance capacitor C _1. Grounded.

In such a power factor correction 12A configuration, the switching current obtained in the primary side series resonance circuit of the switching converter section 102A is applied to the magnetic coupling transformer MCT.
_Will flow through the primary winding L _P. As a result, in the magnetic coupling transformer MCT, the primary winding L _P to the secondary winding Li
The alternating voltage of the switching cycle is excited in _A , so that the switching voltage is superimposed on the charging path to the smoothing capacitor Ci ₁ . That is, in the present embodiment, the switching output is fed back to the rectified output line by the magnetic coupling of the magnetic coupling transformer MCT. As a result of the switching voltage fed back in this way, the fast recovery type diode D ₂ operates so as to be intermittent in the switching cycle. As a result, the conduction angle of the AC input current is expanded by the same operation as described above. It will be.

Further, the switching converter section 102B
Also in the power factor correction circuit 12B corresponding to, by the same operation as that of the power factor correction circuit 12A, in this case, the switching voltage is superimposed on the charging path to the smoothing capacitor Ci _2, and the AC input current It acts to increase the conduction angle. In this way, the power factor correction circuit 12A,
As a result of increasing the conduction angle of the AC input current by 12B,
For example, the AC input current I _AC as shown in FIG. _2E is obtained, and it is possible to improve the power factor. By the operation of the power factor correction circuits 12A and 12B, the normal mode low-pass filter LPF blocks the harmonic current of the switching cycle which is about to flow from the rectified output line to the commercial AC power supply AC side.

The above-described respective embodiments up to now correspond to a heavy load in the range of load power of 250 W to 600 W and a single range of AC input voltage AC100V system or AC200V system, and particularly to AC200V system. Although the configuration of the power supply circuit is shown to be suitable for the power supply circuit, the switching power supply circuit of the present invention is preferably used as a power supply circuit corresponding to a single range of the AC input voltage of AC100V. Will be described.

FIG. 5 is a circuit diagram showing an embodiment of the switching power supply circuit as described above. The same parts as those of the power supply circuits shown in FIGS. 1, 3, and 4 shown as the embodiments so far are designated by the same reference numerals and the description thereof will be omitted. In the power supply circuit shown in this figure, the voltage doubler rectification / power factor correction circuits 13A, 13B, 1 are connected in parallel to the commercial AC power supply AC.
3C is provided. Double voltage rectification / power factor correction circuit 13
A, 13B, and 13C are smoothing capacitors Ci _A1 -Ci _B1 , Ci _A2- Ci _B2 , and Ci provided corresponding to each other.
It is adapted to form a voltage doubler rectifier circuit with each series connection of _A3- Ci _B3 . The switching converter unit 103A, 103B, 103C, respectively smoothing capacitor _{Ci A1 -Ci B1, Ci A2 -Ci} B2, Ci A3 -Ci
_The rectified and smoothed voltage obtained by each series connection of _B3 is driven as an operating power source, and the switching converter unit 103A,
The stabilized secondary side DC output voltages E _O1 , E _O2 , and E _O3 are obtained from 103B and 103C, respectively.
That is, in the present embodiment, the power supply circuit unit including [double voltage rectification / power factor correction circuit-switching converter unit] is provided in parallel with the commercial AC power supply AC.

Since the switching converter units 103A, 103B, 103C shown in this figure have the same circuit configuration as the switching converter unit shown in FIG. 1, the same reference numerals are given to the inside of the circuits. The description of the switching operation and constant voltage control will be omitted.

The voltage doubler rectification / power factor correction circuit 13
The operations of A, 13B and 13C are as follows. For example, in the voltage doubler rectification / power factor correction circuit 13A, first, a filter choke coil L _NA inserted in series with the positive electrode line of the commercial AC power supply AC and a filter capacitor C _NA provided in parallel with the commercial AC power supply AC are used. It forms a normal mode low pass filter. The rectifier diode D ₁₁ is inserted in series between the filter choke coil L _NA and the positive electrode terminal of the smoothing capacitor Ci _{A1 such} that the cathode is connected to the positive electrode terminal of the smoothing capacitor Ci _A1 . The rectifying diode D ₁₂ is a rectifying diode D _12.
The cathode is connected to the anode of _{11 and} the anode is connected to the primary side ground. It should be noted that the rectifying diodes D ₁₁ and D ₁₂ in this case are of a high-speed recovery type in response to the high-frequency current of the switching cycle of the switching converter section flowing through the rectifying current path as described later. In this case, the primary winding N ₁ of the insulating converter transformer PIT of the switching converter unit 103A is connected to the series resonance capacitor C ₁
Is connected to the connection point of the rectifying diode D ₁₁ and the rectifying diode D ₁₂ via the rectifying diode D ₁₁ , so that the switching output obtained in the primary side series resonance circuit is capacitively coupled to the series resonance capacitor C _1. The double voltage rectified current is fed back to the path through which it flows. Further, in this case, two resonance capacitors C ₂ are provided and connected in parallel to the rectifying diode D ₁₁ and the rectifying diode D ₁₂ , respectively.

The smoothing capacitors Ci _A1 and Ci _{B1 are} added to the voltage doubler rectifying / power factor improving circuit 13A having the above-mentioned configuration.
Is connected in series between the cathode of the rectifying diode D _{11 and} the ground on the primary side, and is connected to the smoothing capacitor Ci _A1.
And a connection point of Ci _B1 are connected to a line on the negative side of the commercial AC power supply AC.

In such a configuration, for example, during a period in which the _AC input voltage VAC is positive, the commercial AC power supply AC is rectified by the rectifying diode D ₁₁ to form a current path for charging the smoothing capacitor Ci _A1 . On the other hand, during the period when the _AC input voltage VAC is negative, the commercial AC power supply AC is rectified by the rectifier diode D ₁₁ to form a path for charging the smoothing capacitor Ci _B1 . As a result, a rectified and smoothed voltage corresponding to approximately twice the _AC input voltage VAC is obtained across the smoothing capacitors Ci _A1 -Ci _B1 connected in series. The power supply circuit is designed to perform double voltage rectification.

Further, in the voltage doubler rectification / power factor correction circuit 13A, as described above, the primary side series resonance circuit of the switching converter section 103A at the subsequent stage is connected to the connection point of the rectification diode D ₁₁ and the rectification diode D _12. Connected,
The switching output is fed back by the capacitive coupling of the series resonance capacitor C ₁ . In this case, the fed back switching output is superimposed on the rectified output through the inductance of the filter choke _LNA as an alternating voltage in the switching cycle, whereby the rectifier diode D ₁₁ and the rectifier diode D ₁₂ rectify in the switching cycle. Operates to interrupt the current. As a result, for example, similarly to the power factor correction circuit 10A in FIG. 1, the power factor correction circuit 10A acts to increase the conduction angle of the rectified input current I ₁ .

Double voltage rectification / power factor correction circuits 13B and 13
C has the same configuration as the above voltage doubler rectification / power factor correction circuit 13A, and is therefore given the same reference numeral. Therefore, in the voltage doubler rectification / power factor correction circuits 13B and 13C as well as in the voltage doubler rectification / power factor correction circuit 13A, voltage doubler rectification is performed with respect to the commercial AC power source, and the voltage doubler is respectively performed. The rectification / power factor correction circuit 13B increases the conduction angle for the rectified input current I ₂ , and the voltage doubler rectification / power factor correction circuit 13C acts to increase the conduction angle for the rectified input current I ₃ .

FIG. 6 is a waveform diagram showing the rectified input currents I ₁ , I ₂ , I ₃ and the AC input current I _AC in the commercial power supply cycle in the power supply circuit of FIG. For example, if the AC input voltage V _AC of AC100V As shown in FIG. 6 (a) is supplied, a voltage doubler rectifier / power factor correction circuit 13 described above
Rectified input current I flowing through A, 13B, and 13C, respectively
_{As for 1} , I ₂ , and I ₃ , waveforms in which the conduction angles are enlarged are obtained as shown in FIGS. 6B, 6C, and 6D, respectively. Then, the AC input current I _AC obtained by combining the rectified input current I _1, I _2, I ₃ is rectified input currents I _1, I as shown in FIG.
₂ , obtained as a waveform in which the conduction angle is expanded to the same extent as I _3, and in the present embodiment, the power factor is actually improved to about 0.8 under a predetermined AC input voltage and load conditions. Is set to be.

In the case of the power supply circuit of this embodiment shown in FIG. 5, for example, the rectifying diode D ₁₁ and the rectifying diode D _{12 are used.}
For, select each with a current capacity of 10A,
No heat sink is required. The rectifying and smoothing capacitors forming the voltage doubler rectifying circuit are 470 μF / 200 each.
It is possible to adopt V. Furthermore, with regard to the filter choke coil L _NA, is intended or structurally similar small Ridoindaku as those described in FIG. 12 above, the filter can also be used small-capacity products for capacitor C _NA, both inexpensive This makes it possible to select small and lightweight parts.

In the power supply circuit of FIG. 5, the AC input current I _AC is 10.1 Arms when the load power is 600 W, for example.
As a result, the effective current increases, but the power conversion efficiency is 92%.
Is obtained, and the power conversion efficiency before power factor improvement is 2% than 90%
Will be improved. Further, in the power supply circuit of FIG. 13 which is a conventional example, the power conversion efficiency at an AC input voltage of 100 V AC is about 84.6% (AC input current I _AC = 8.8 Arm.
Although it is described as s), the power loss is remarkably reduced compared to the above. Further, when the AC input voltage is AC 100 V, the input power is 694 W in the power supply circuit of FIG. 13, whereas it is 652 W in the power supply circuit of FIG.
The result is that the power consumption is reduced by 7 W.

As described above, also in the power supply circuit of the present embodiment, when compared with the power supply circuit shown in FIG. 13, it is possible to further reduce the size / weight and reduce the cost, and Also, the characteristics such as power conversion efficiency can be improved.

FIG. 7 is a circuit diagram showing a configuration of a switching power supply circuit according to still another embodiment of the present invention. Note that this power supply circuit is also suitable for being applied to a power supply circuit corresponding to a single range of an AC input voltage AC100V system in the same manner as the power supply circuit shown in the embodiment of FIG. 5, for example. Rectification / power factor correction circuits 14A, 14B, 1
4C is provided to improve the power factor, the same parts as those in FIG. 5 are denoted by the same reference numerals and the description thereof will be omitted. In addition, the switching converter unit 104 of FIG.
A, 104B, and 104C are described in FIG.
Since it has the same configuration as that of the switching converter section shown in (1), the same parts are designated by the same reference numerals, and the description of the switching operation and the constant voltage control will be omitted.

In the power supply circuit shown in this figure, a normal mode low-pass filter LPF formed by a filter choke coil L _N and a filter capacitor C _N is provided for the commercial AC power supply AC, and will be described later [double voltage rectification / Power factor correction circuit-switching converter section] is commonly operated for parallel connection of circuit sections. Therefore, in this case, one set of normal mode low-pass filters may be used regardless of the number of sets corresponding to the [doubler rectification / power factor correction circuit-switching converter unit] provided in parallel with the commercial AC power supply AC. It will be possible.

Since the voltage doubler rectification / power factor correction circuits 14A, 14B, and 14C provided in the power supply circuit of this embodiment have the same configuration, they are denoted by the same reference numerals. For example, in the voltage doubler rectification / power factor correction circuit 14A, the voltage doubler rectification / power factor correction circuit 1 included in the power supply circuit of FIG.
Two rectifier diodes D ₁₁ and D ₁₂ for voltage doubler rectification are provided by the same connection form as 3A. Resonance capacitors C ₂ and C ₂ are connected in parallel to the rectifier diodes D ₁₁ and D ₁₂ . Further, in this case, the winding Li of the choke coil CH is inserted in series between the filter choke coil L _N and the connection point of the rectifying diodes D ₁₁ and D ₁₂ , and in this case also, the double voltage rectification / Power factor correction circuit 14A
Switching converter unit 104A connected to the subsequent stage
The primary side series resonance circuit is connected to the connection point of the rectifier diodes D ₁₁ and D ₁₂ . The choke coil CH used in the present embodiment is constructed by winding a litz wire or the like around a core having a size of about EI-28 made of, for example, a ferrite material.

In the voltage doubler rectification / power factor correction circuit 14A having such a configuration, similar to the power factor correction in the power supply circuit of FIG. 3, for example, the primary side series resonance circuit of the switching converter 104A is magnetically coupled by the choke coil CH. It is said that the method of feeding back the switching output obtained in the above is adopted. Therefore, also in this case, the choke coil CH
Due to the alternating voltage of the switching cycle superimposed on the rectified output flowing through the inductance of the winding Li of the high-speed recovery type, the rectifying diodes D ₁₁ and D _{12 of the} high-speed recovery type intermittently switch the rectifying current in the switching cycle. By the same operation as the power supply circuit described above, the conduction angle of the AC input current is expanded to improve the power factor.

In addition, the voltage doubler rectification / power factor correction circuit 14B
-For the power supply circuit unit including the switching converter unit 104B] and the [double voltage rectification / power factor correction circuit 14C-switching converter unit 104C], the above-mentioned [double voltage rectification / power factor correction circuit 14A-switching converter unit 104A] is also used. The same operation as that of the power supply circuit section can be obtained, and thereby the conduction angle of the AC input current is expanded to improve the power factor.

FIG. 8 is a circuit diagram showing a configuration of a switching power supply circuit according to still another embodiment of the present invention.
Also in this case, it is suitable as a power supply circuit corresponding to a single range of AC input voltage AC100V system and heavy load, and is configured to have a voltage doubler rectifier circuit. Since the double voltage rectification / power factor correction circuit in the subsequent stage operates in parallel with each other, the same parts as those of the power supply circuits of FIGS. Omit it.

Further, in the case of this power supply circuit, the two sets of switching converter sections 105A and 105B provided in parallel with the commercial AC power supply AC are of the half-bridge type separately excited current resonance type converter. . Further, the voltage doubler rectification / power factor correction circuits 15A and 15B of the power supply circuit shown in FIG. 8 are configured by applying a configuration for improving the power factor to the voltage doubler rectifier circuit by the magnetic coupling transformer MCT. Therefore, the same parts as those of the switching converter unit of the power supply circuit shown in FIG.

For example, a voltage doubler rectifier / power factor correction circuit 15A
Is equipped with a magnetic coupling transformer MCT,
In this case, one end of the secondary winding Li of the magnetic coupling transformer MCT is connected to the connection point of the high-speed recovery type rectifier diodes D ₁₁ and D ₁₂ , and the other end of the filter choke coil L _N of the normal mode low-pass filter LPF. It is connected to the positive electrode line of the commercial AC power supply AC so as to be connected to the end portion. The resonance capacitor C ₂ is provided in parallel with the secondary winding Li of the magnetic coupling transformer MCT, and the primary winding L _P of the magnetic coupling transformer MCT is connected to the primary side series resonance circuit of the switching converter unit 105A. Are inserted in series.

According to such a configuration, in the voltage doubler rectification / power factor correction circuit 15A, the switching output is superimposed on the path of the voltage doubler rectified current via the magnetic coupling of the magnetic coupling transformer MCT. Therefore, by the same operation as described with reference to FIG. 3, it operates so as to increase the conduction angle of the input current flowing from the commercial AC power supply AC into the voltage doubler rectification / power factor correction circuit 15A. Then, in the voltage doubler rectification / power factor correction circuit 15B provided corresponding to the switching converter unit 105B, similarly, voltage doubler rectification is performed together with the smoothing capacitors Ci _A2 and Ci _B2 , and the feedback switching output is provided. Based on this, the operation is performed so as to increase the conduction angle of the input current, the waveform of the AC input current flowing through the commercial AC power supply AC approaches the waveform of the AC input voltage, and the power factor is improved.

By the way, in each of the above-described embodiments, the AC input voltage AC100V system, or 2
The configuration of the switching power supply circuit, which is suitable when applied to the power supply circuit corresponding to the 00V single range and heavy load, has been described. The AC input voltage AC is shown in the circuit diagram of FIG.
1 shows an embodiment of a switching power supply circuit that is compatible with a so-called wide range capable of sharing a 100 V system and a 200 V system and that can handle a heavy load of about 250 W to 600 W. The same parts as those of the switching power supply circuits shown in FIGS. 1 and 5 described above as the embodiments are designated by the same reference numerals and the description thereof will be omitted.

In this power supply circuit, the switching converter units 106A, 106B, 1 are connected to the commercial AC power supply AC.
06C is provided in parallel, and for each of the preceding stages,
Power factor correction rectification circuits 16A, 16B, and 16C are connected and provided. In other words, in this case, [power factor correction rectifier circuit-
A plurality of power supply circuit units including a switching converter unit are provided in parallel with the commercial AC power supply AC so as to handle a heavy load. The switching converters 106A, 106B and 106C are respectively composed of smoothing capacitors [Ci _A1 -Ci _B1 ], [Ci _A2- Ci _B2 ],
It is driven by using the voltage across [Ci _A3 -Ci _B3 ] as the operating power supply. In addition, the switching converter units 106A, 10
6B and 106C have the same configurations as those of the switching converter units shown in FIGS. Further, in this power supply circuit, as shown by the broken line, the filter capacitor C _N is the commercial AC power supply AC.
Power factor correction rectifier circuit 1 which is provided in parallel with
Filter choke coils L _NA , L _NA , and L _NA inserted in the rectifying input line on the positive electrode side of 6A, 16B, and 16C.
At the same time, a normal mode low pass filter is formed. That is, in this case, the power factor correction rectifier circuit 1
The filter capacitor C _N is commonly provided for the parallel connection of 6A, 16B, and 16C.

In this case, the power factor correction rectifier circuits 16A, 16
Since B and 16C have the same configuration, they are designated by the same reference numerals. In the power factor correction rectifier circuit 16A, first, as described above, the filter choke coil L
_NA is serially inserted in the positive rectification input line to the rectification circuit of the power factor correction rectification circuit 16A to form a normal mode low-pass filter with the filter capacitor C _N. Further, in this case, a bridge rectifier circuit D _1A is provided and is provided for the commercial AC power supply AC as shown in the figure. This bridge rectifier circuit D _1A responds to intermittent rectification current in a switching cycle as will be described later, and accordingly, as shown in the figure, high-speed recovery type rectification diodes D _F1 , D _F2 ,
D _F3 and D _F4 are used. In this case, two resonance capacitors C ₂ are provided, and each bridge rectifier circuit D
_It is provided in parallel with the ₁ A rectifying diodes D _F1 and D _F2 .

In the power factor correction rectifier circuit 16A, the positive output terminal of the bridge rectifier circuit D _1A (the connection point of the rectifier diodes D _F2 and D _F4 ) is connected to the positive terminal of the smoothing capacitor Ci _A1 . Further, the negative input terminal (the connection point of the rectifier diodes D _F3 and D _F4 ) is connected to the connection point of the smoothing capacitor Ci _B1 via the switch section S ₁ of the electromagnetic relay RL. In this case, the primary side series resonance circuit is the positive input terminal of the bridge rectifier circuit D _1A (rectifier diode D _F1 ,
It is connected to the connection point of D _F2 ) to supply the switching output to the path of the rectified current as described later.

The power factor correction rectifier circuit 16B is also connected to the smoothing capacitors Ci _A2- Ci _B2 side via the switch section S ₂ of the electromagnetic relay RL in the same manner as described above, and the power factor correction rectifier circuit 16C is Smoothing capacitor Ci _A3 −
It is connected to the Ci _B3 side via the switch section S ₃ of the electromagnetic relay RL. The primary side series resonance circuits of the switching converter units 106B and 106C are connected to the power factor correction rectification circuits 16B and 1B by the same connection configuration as described above.
6C is connected to the positive input terminal of each bridge rectifier circuit D _1A .

Electromagnetic relay RL shown in the power supply circuit of this figure
Is for one relay drive circuit RL _D as shown
A type is used in which the switch units S ₁ , S ₂ and S ₃ are interlocked and switched. For example, the relay drive circuit RL _D is connected to a standby power supply circuit unit for standby, which is not shown here, and has an AC input voltage of AC 150 or more and 150 V or less, for example.
The relay drive circuit RL _D is switched between conduction and non-conduction of current. And this relay drive circuit R
By the excitation effect of the L _D, in the case of the AC input voltage AC150 or more is controlled to switch section S _1, S _2, S ₃ is turned off, the switch section S ₁ when the AC input voltage AC150 or less, S ₂ and S ₃ are controlled to be turned on.

The rectifying operation of the power supply circuit of the present embodiment equipped with such an electromagnetic relay RL is performed by the power factor improving rectifier circuit 1
6A will be described as an example. For example, if the AC input voltage is AC15
When it is 0 or less, that is, when the AC input voltage of AC100V system is input to the commercial AC power supply AC, the switch unit S ₁ is controlled to be in the ON state by the operation of the electromagnetic relay RL described above. As a result, the smoothing capacitor Ci _A1 ,
The connection point of Ci _B1 is connected to the negative line of the commercial AC power supply AC. In this case, the smoothing capacitor Ci _A1 is charged through the rectifying diode D _F2 while the commercial AC power supply AC is positive, and the rectifying diode D A is charged while the commercial AC power supply AC is negative.
By charging the smoothing capacitor Ci _B1 via _F1 , a voltage doubler rectifier circuit for voltage rectifying the commercial AC power supply AC is formed.

On the other hand, when the AC input voltage is set to 200 V and the AC input voltage of AC 150 V or more is input to the AC power source AC, the switch section S ₁ is turned off by the electromagnetic relay RL. The connection point of the smoothing capacitors Ci _A1 and Ci _B1 and the negative line of the commercial AC power supply AC are cut off by being controlled. In this state, the commercial AC power source AC is full-wave rectified by the bridge rectifier circuit D _1A , and the smoothing capacitors Ci _A1 , Ci are rectified by the rectified output.
_The operation is to obtain the full-wave rectified smoothed voltage by charging the series connection of _B1 . Therefore, in this case, commercial AC power supply A
A rectified smoothed voltage corresponding to the level of C is obtained across smoothing capacitors Ci _A1 and Ci _B1 connected in series. The switching converter unit 106A performs a switching operation by using the doubled voltage rectified voltage or the full-wave rectified smoothed voltage thus obtained as an operating power source to finally obtain the stabilized secondary side DC output voltage E _O1. To work.

In this power factor correction rectifier circuit 16A,
As described above, since the primary side series resonance circuit of the switching converter unit 106A is connected to the connection point of the rectification diodes D _F1 and D _F2 forming the bridge rectification circuit D _1A , the series resonance capacitor C ₁ The switching output obtained in the primary side series resonance circuit is fed back to the rectification input line in the power factor correction rectification circuit 16A via the capacitive coupling. As a result, in the case of the double voltage rectification operation at the time of AC input voltage AC100V system,
In both cases of the full-wave rectification operation in the AC200V system, the switching voltage is superimposed on the path through which the rectification current flows, and the rectification diodes D _F1 and D _F2 intermittently switch the rectification current in the switching cycle. To be Therefore, the conduction angle of the rectified input current of the commercial cycle flowing from the commercial AC power supply AC into the rectification path of the power factor correction rectification circuit 16A is increased.

Then, the power factor correction rectification circuits 16B and 16C
In the same manner, the switching units S ₂ and S ₃ are switching-controlled by the operation of the electromagnetic relay RL, so that the voltage doubler rectifying operation is performed in the AC input voltage AC100V system (AC150V or less) in the same manner as the power factor correction rectifying circuit 16A. Obtained,
In the AC200V system (AC150V or more), the switching is automatically performed so that the full-wave rectification smoothing operation by the bridge rectification circuit D _1A can be obtained. In addition, the power factor correction rectifier circuits 16B and 16
At C, the conduction angle of the rectified input current is expanded by the same operation as that of the power factor correction rectifier circuit 16A, and as a result, the rectified input currents of the power factor correction rectifier circuits 16A, 16B, and 16C are combined. The conduction angle of the obtained AC input current is also expanded to improve the power factor. Also in the present embodiment N, the required components in the power supply circuit are selected so that the power factor improvement is about 0.8.

In the power supply circuit of the present embodiment configured as described above, for example, four fast recovery type rectifying diodes D _F1 and D _F forming the bridge rectifying circuit D _1A are provided.
Each of _F2 , D _F3 , and D _F4 has a current capacity of 10
A heat sink is required for the rectifying diodes D _F1 and D _F2 that select and discontinue the rectifying current in the switching cycle, but the rectifying diodes D _F3 and D _F4 are not required. For the smoothing capacitors provided for each power factor correction rectifier circuit, 1000 μF /
400V is selected. Further, regarding the filter choke coil L _NA, it is considered that the same small lead-inductor structure as described above with reference to FIG. 12 may be used, and regarding the filter capacitor C _NA , 1 μF /
Although 400V is used, the power factor correction rectifier circuit of the present embodiment does not generate a high level noise unlike the active filter, and therefore one set can be used as shown in FIG.

Further, in the power supply circuit of FIG. 9, for example, when the load power is 600 W and the AC input voltage is AC 100 V, the power factor is improved to about 0.82, and the AC input current level, the power conversion efficiency, and the input power are previously calculated. Its form is equivalent to that of the switching power supply circuit shown in FIG. When the load power is 600 W and the AC input voltage is AC 200 V, the power factor is 0.
The power conversion efficiency is 93% and the input power is 645.
W (AC input current level is 4.8 Arms), which is shown in FIG.
The power conversion efficiency of the power supply circuit is 86.5%, and the input power is 694W. Therefore, also in the switching power supply circuit of the present embodiment, when compared with the power supply circuit shown in FIG. 13, it is possible to achieve a smaller size / lighter weight and a lower cost, and an AC input voltage AC100V.
In both cases of the system and the 200V system, improvement of power conversion efficiency and reduction of power consumption can be achieved.

FIG. 10 is a circuit diagram showing a configuration of a switching power supply circuit according to still another embodiment of the present invention. Like the power supply circuit of FIG. 9 described above, the power supply circuit shown in this figure is compatible with a wide range, and the electromagnetic relay RL automatically performs double voltage rectification and full-wave rectification for AC input voltage AC100V system and AC200V system. Since the configuration is changed over, the same components as those in FIG. 9 are designated by the same reference numerals and the description thereof will be omitted. Further, the switching converter units 107A, 107B, 10 in the power supply circuit of FIG.
7C has the same configuration as the switching converter unit shown in FIG. 3 and FIG. 7 as an embodiment, the same parts are designated by the same reference numerals, and the switching operation and the constant voltage control are performed. Is omitted.

In the power supply circuit shown in this figure, a pair of normal mode low pass filters LPF formed by a filter choke coil L _N and a filter capacitor C _N are provided for the commercial AC power supply AC, and the power factor of the latter stage The improved rectifier circuit-switching converter section] acts in common on the parallel connection of the circuit sections to block the harmonic current flowing into the commercial AC power supply.

The power factor correction rectifier circuits 17A, 17B, and 17C provided in the power supply circuit shown in this figure have the same structure, and are designated by the same reference numerals. For example, in the power factor correction rectifier circuit 17A, the bridge rectifier circuit D _1A , the same as the power factor correction rectifier circuit 17A of the power supply circuit of FIG.
Resonance capacitors C ₂ and C ₂ are provided. Then, in this case, the winding Li of the choke coil CH is inserted between the filter choke coil L _N of the normal mode low-pass filter LPF and the connection point of the rectifying diodes D _F1 and D _F2 . That is, the winding L of the choke coil CH
i is provided in series with the positive rectification input line of the power factor correction rectification circuit 17A.

The power factor correction rectifier circuit 14A having such a configuration
According to the above, the switching converter unit 1 is formed by magnetic coupling of the choke coil CH shown in FIGS. 3 and 7, for example.
The switching output obtained in the primary side series resonance circuit of 07A is fed back to improve the power factor. Therefore, in this case, the rectified output that flows through the inductance of the winding Li of the choke coil CH is used in both cases of the double voltage rectification corresponding to the AC input voltage AC100V system and the full-wave rectification smoothing corresponding to the AC200V system. On the other hand, the alternating voltage of the switching cycle is superimposed, and the operation of the high-speed recovery type rectifying diodes D _F1 and D _F2 to intermittently connect the rectified current in the switching cycle is obtained. For this reason,
The conduction angle of the rectified input current is expanded by the same operation as that of the power supply circuit of FIGS. Further, also in the power factor correction rectifier circuits 14B and 14C, the rectification operation is switched in the same manner as the power factor correction rectifier circuit 14A, and
As a result of the conduction angle of the rectified input current being enlarged, the conduction angle of the AC input current is enlarged and the power factor is improved.

The circuit diagram of FIG. 11 is adapted to a wide range, and the electromagnetic relay RL automatically switches between the double voltage rectification and the full-wave rectification corresponding to the AC input voltage AC100V system and AC200V system. 1 is a circuit diagram showing a configuration of a switching power supply circuit as an embodiment. In addition, in the power supply circuit shown in this figure, one set of normal mode low-pass filters LPF is configured to act in common on the parallel connection of the power factor correction rectifier circuits in the subsequent stages. Therefore, the same parts as those in FIGS. 9 and 10 are designated by the same reference numerals and the description thereof will be omitted.

Further, in the case of the power supply circuit of this embodiment, three sets of switching converter units 108A, 108B and 10 provided in parallel with the commercial AC power supply AC are provided.
8C is configured as a half-bridge type separately excited current resonance type converter. Further, the power factor correction rectification circuits 18A, 18B and 18C of the power supply circuit shown in this figure apply a configuration for improving the power factor by the magnetic coupling transformer MCT to the switching circuit of double voltage rectification / full wave rectification. There is. Therefore, the same parts as those in FIGS. 3 and 8 are designated by the same reference numerals and the description thereof will be omitted.

For example, in the power factor correction rectifier circuit 18A, the secondary winding Li of the magnetic coupling transformer MCT is inserted in series with the positive input line of the bridge rectifier circuit D _1A . That is, in this case, the secondary winding Li includes the filter choke coil of the normal mode low-pass filter LPF and the rectifying diodes D _F1 and D _{F2 of the} bridge rectifying circuit D _1A.
Are inserted in series between the connection points. In this case, one set of resonance capacitors C ₂ is provided in parallel with the secondary winding Li of the magnetic coupling transformer MCT. The primary winding L _P of the magnetic coupled transformer MCT is inserted in series with the primary side series resonant circuit of the switching converter portion 108A.

Power factor correction rectifier circuit 1 having such a connection configuration
Even if it is set to 8 A, the switching output will be superimposed on the rectified input line via the magnetic coupling of the magnetic coupling transformer MCT so as to be fed back, and at the time of double voltage rectification corresponding to the AC input voltage AC100V system. And AC20
In any case of the full-wave rectification smoothing corresponding to the 0 V system, it acts to increase the conduction angle of the rectified input current flowing from the commercial AC power source AC into the power factor correction rectifier circuit 18A. Also in the power factor correction rectifier circuit 18B, the conduction angle of the rectified input current to the power factor correction rectifier circuit 15B is expanded based on the switching output fed back from the primary side series resonance circuit of the switching converter unit 108B. The power factor correction rectifier circuit 18C operates in the same manner to increase the conduction angle of the rectified input current. As a result, the power factor of the AC input current flowing through the commercial AC power supply AC is improved. In the power supply circuits shown in FIGS. 9, 10, and 11, instead of the electromagnetic relay RL used for switching between the full-wave rectifier circuit and the voltage doubler rectifier circuit, a bidirectional thyristor such as a triac is included. Other elements may be used.

Further, the power factor improving method of the present invention described so far in each of the above-described embodiments is the self-excited oscillation type / other-excited oscillation type as the current resonance type switching power supply circuit, the switching frequency control method (drive transformer). Is an orthogonal PRT (Power Regulating Transformer)) /
Series resonant frequency control method (isolation transformer orthogonal type PR
T), half bridge coupling type / full bridge coupling type of switching element, and common mode of normal mode low-pass filter composed of filter capacitor and filter choke coil. It is needless to say that the present invention can be applied to a power supply circuit and is not limited to the combination patterns shown as the embodiments in each of the above figures.

[0106]

As described above, according to the present invention, a plurality of current resonance type switching converters are provided in parallel with a commercial AC power source to form a power supply circuit corresponding to a heavy load, and then each current resonance type By providing a power factor correction circuit with a simple structure for the switching converter by feeding back the switching output obtained in the primary side series resonant circuit, power loss can be improved as in the conventional case. It becomes unnecessary to provide a large-scale power factor correction circuit such as an active filter having a large size. As a result, the present invention has the effect of significantly reducing power loss and significantly improving power conversion efficiency. As a result, the heat dissipation plate material to be provided in the power supply circuit is also reduced. Further, in the present invention, since the input power is also reduced and the power consumption is saved, the reliability of the power supply circuit is improved together with the improvement of the power conversion efficiency.

Further, for example, in an active filter, it is necessary to select a switching element of a high power MOS-FET, an inductor such as a filter choke coil or choke coil using a large toroidal core, a high withstand voltage filter capacitor, and the like. However, in the present invention, the switching element for improving the power factor is omitted, and the normal mode low-pass filter is also formed by a small and lightweight group of components. Therefore, the power supply circuit can be downsized / lightened and the cost can be reduced. Can be realized.

As described above, the switching power supply circuit of the present invention is more compact and lighter in weight and lower in cost than the switching power supply circuit configured to improve the power factor by the active filter, and improves the power conversion efficiency. The electrical characteristics are also improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a switching power supply circuit as an embodiment of the present invention.

FIG. 2 is a waveform diagram showing an operation of the switching power supply circuit of the embodiment in a commercial AC power supply cycle.

FIG. 3 is a circuit diagram showing a switching power supply circuit according to another embodiment.

FIG. 4 is a circuit diagram showing a switching power supply circuit as still another embodiment.

FIG. 5 is a circuit diagram showing a switching power supply circuit as still another embodiment.

6 is a waveform diagram showing an operation of the switching power supply circuit shown in FIG. 5 in a commercial AC power supply cycle.

FIG. 7 is a circuit diagram showing a switching power supply circuit as still another embodiment.

FIG. 8 is a circuit diagram showing a switching power supply circuit as still another embodiment.

FIG. 9 is a circuit diagram showing a switching power supply circuit as still another embodiment.

FIG. 10 is a circuit diagram showing a switching power supply circuit as still another embodiment.

FIG. 11 is a circuit diagram showing a switching power supply circuit as still another embodiment.

FIG. 12 is a perspective view showing a filter choke coil used in the itching power supply circuit of the present embodiment.

FIG. 13 is a circuit diagram showing a switching power supply circuit as a conventional example.

FIG. 14 is a waveform diagram showing an AC input current with respect to an AC input voltage in a conventional switching power supply circuit.

FIG. 15 is a waveform diagram showing an AC input current with respect to an AC input voltage in a conventional switching power supply circuit.

FIG. 16 is a perspective view showing a structure of a filter choke coil and a choke coil used in a conventional switching power supply circuit.

[Explanation of symbols]

1 Control Circuit 2 Oscillation Drive Circuit 3 Starter Circuit 4 Error Amplifier 10A to 10C, 11A to 11C, 12A, 12B Power Factor Correction Circuit 13A to 13C, 14A to 14C, 15A, 15B Double Voltage Rectification / Power Factor Correction Circuit 16A to 16C , 17A to 17C, 18A to 18C Power factor improving rectifier circuit L _N , L _NA filter choke coil C _N , C _NA filter capacitor D _1A , D _1B , D _1C bridge rectifier circuit D ₂ fast recovery diode CH choke coil PIT ( PRT) Isolation converter transformer CDT (PRT) converter Drive transformer Q ₁ , Q ₂ , Q ₁₁ , Q ₁₂ Switching element C ₁ Series resonance capacitor N ₁ Primary winding C ₂ Resonance capacitor

Claims (30)

[Claims] 1. A primary side series resonance circuit formed by connecting in series a primary side winding of an insulation transformer and a series resonance capacitor, wherein a smoothing DC voltage obtained by rectifying and smoothing a commercial power supply is input to perform a switching operation. In order to improve the power factor, the current resonance type switching converter means for outputting a DC output voltage from the secondary side of the insulation converter transformer and the switching output of the switching converter means for the rectified current path are fed back. And a plurality of power factor improving converters formed by the power factor improving means, the plurality of power factor improving converters being independently connected to a commercial power source. Switching power supply circuit. 2. The power factor improving means includes a filter choke coil and a high-speed recovery type diode which are provided in series with a path of a rectified current, and a filter capacitor which forms a low pass filter together with the filter choke coil. The switching power supply circuit according to claim 1, wherein: 3. The primary side series resonance circuit is connected to a connection point of the filter choke coil and a high speed recovery type diode to feed back a switching output. The switching power supply circuit described. 4. The switching power supply circuit according to claim 2, further comprising a resonance capacitor provided in parallel with the fast recovery diode. 5. The power factor improving means comprises a filter choke coil, a high speed recovery type diode and a winding of a choke coil which are provided in series with a path of a rectified current, and a filter which forms a low pass filter together with the filter choke coil. The switching power supply circuit according to claim 1, further comprising a capacitor. 6. The primary side series resonance circuit is connected to a connection point between the high speed recovery type diode and a winding of a choke coil to feed back a switching output. The switching power supply circuit according to claim 5. 7. The switching power supply circuit according to claim 5, further comprising a resonance capacitor provided in parallel with the winding of the choke coil. 8. The power factor improving means comprises a first winding and a second winding.
A magnetic coupling transformer formed by magnetically coupling the windings of, the filter choke coil, the high speed recovery type diode and the first winding are inserted in series with respect to the path of the rectified current, and the second winding is connected. The switching power supply according to claim 1, wherein the winding is connected in series to the primary side series resonance circuit, and is provided with a filter capacitor that forms a low-pass filter together with the filter choke coil. circuit. 9. The switching power supply circuit according to claim 8, further comprising a resonance capacitor provided in parallel with the first winding. 10. The switching device according to claim 1, wherein a plurality of sets of rectifying means for rectifying a commercial power source are provided corresponding to the plurality of power factor improving converter units. Power supply circuit. 11. The rectifying means for rectifying the commercial power source is a set, and is provided in common to the plurality of power factor improving converter units. The switching power supply circuit described. 12. A filter choke coil and a filter capacitor forming the low-pass filter, or the filter capacitor is set as one set and is provided commonly to the plurality of power factor improving converter units. The switching power supply circuit according to any one of claims 2 to 9. 13. A voltage doubler rectifying means for rectifying a voltage of a commercial power source, and a primary side series resonant circuit formed by series connection of a primary side winding of an insulating transformer and a series resonant capacitor. With respect to the rectifying current path of the current resonance type switching converter means for inputting the obtained smoothed DC voltage to perform the switching operation and outputting the DC output voltage from the secondary side of the insulating converter transformer, , A plurality of power factor improving converter units each comprising a switching output of the switching converter unit and a power factor improving unit adapted to improve the power factor, and the plurality of power factor improving converter units are commercially available. A switching power supply circuit that is independently connected to a power supply. 14. The power factor improving means includes a filter choke coil inserted in series in a rectification path of the voltage doubling rectification means, and a filter capacitor provided so as to form a low-pass filter together with the filter choke coil. 14. The switching power supply circuit according to claim 13, wherein the primary side series resonance circuit is connected so that a switching output is applied to a rectifying element forming the voltage doubler rectifying means. 15. The power factor improving means forms a low pass filter together with a filter choke coil, a choke coil winding, and the filter choke coil which are inserted in series in a rectification path of the voltage doubling rectification means. 14. The primary side series resonance circuit is connected so that a switching output is applied to a rectifying element forming the voltage doubler rectifying means, the filter condenser being provided. Switching power supply circuit. 16. The switching power supply circuit according to claim 14, wherein a resonance capacitor is provided in parallel with the rectifying element forming the voltage doubler rectifying means. 17. The power factor improving means includes a magnetic coupling transformer formed by magnetically coupling a first winding and a second winding, and the filter choke coil and the first winding are connected to each other. A filter that is inserted in series in the rectification path of the voltage doubler rectification means, the second winding is connected in series to the primary side series resonance circuit, and is provided so as to form a low-pass filter together with the filter choke coil. The switching power supply circuit according to claim 13, wherein the switching power supply circuit comprises a capacitor. 18. The switching power supply circuit according to claim 17, wherein a resonance capacitor is provided in parallel with the first winding. 19. A filter choke coil and a filter capacitor forming the low-pass filter, or the filter capacitor is set as one set and is commonly provided for the plurality of power factor improving converter units. The switching power supply circuit according to any one of claims 14 to 18. 20. Rectification means capable of switching between a full-wave rectification circuit for full-wave rectifying a commercial power supply according to the voltage value of an AC input voltage and a double-voltage rectification circuit for doubling the commercial power supply. A primary side series resonance circuit formed by connecting a primary side winding of an insulation transformer and a series resonance capacitor in series is provided, and a smoothing DC voltage obtained based on the rectified output of the rectifying means is input to perform a switching operation. The switching output of the switching converter means is fed back to the current resonance type switching converter means for outputting a DC output voltage from the secondary side of the insulating converter transformer and the rectification current path of the rectification means to improve the power factor. A plurality of power factor improving converters each including the power factor improving means, and the plurality of power factor improving converters are connected to a commercial power source. A switching power supply circuit characterized by being connected independently of each other. 21. The power factor improving means includes a filter choke coil inserted in series in a rectifying path of the rectifying means, and a filter capacitor provided so as to form a low-pass filter together with the filter choke coil, 21. The switching power supply circuit according to claim 20, wherein the primary side series resonance circuit is connected so that a switching output is applied to a rectifying element forming rectifying means. 22. The power factor improving means is provided so as to form a low pass filter together with a filter choke coil inserted in series in a rectifying path of the rectifying means, a winding of the choke coil, and the filter choke coil. 21. The switching power supply circuit according to claim 20, further comprising a filter capacitor, wherein the primary side series resonant circuit is connected so that a switching output is applied to a rectifying element forming the rectifying means. 23. The switching power supply circuit according to claim 21, wherein a resonance capacitor is provided in parallel with the rectifying element forming the rectifying means. 24. The power factor improving means includes a magnetic coupling transformer formed by magnetically coupling a first winding and a second winding, and the filter choke coil and the first winding are connected to each other. A filter capacitor that is inserted in series in the rectification path of the rectification means, the second winding is connected in series to the primary side series resonance circuit, and is provided so as to form a low-pass filter together with the filter choke coil. The switching power supply circuit according to claim 20, wherein the switching power supply circuit comprises: 25. The switching power supply circuit according to claim 24, wherein a resonance capacitor is provided in parallel with the first winding. 26. The filter choke coil and the filter capacitor forming the low-pass filter, or the filter capacitor is a set and is commonly provided for the plurality of power factor improving converter units. The switching power supply circuit according to any one of claims 21 to 25. 27. The switching power supply circuit according to claim 2, wherein the filter choke coil is formed by winding a single wire around a drum-shaped core. 28. The switching converter means comprises:
A constant voltage control is performed by varying a switching frequency of a switching element of the switching converter means based on a DC output voltage obtained on the secondary side of the isolation transformer. The switching power supply circuit according to any one of claims 1 to 27. 29. The switching converter means comprises:
2. The constant voltage control is performed by changing the magnetic flux of the insulation transformer based on the DC output voltage obtained on the secondary side of the insulation transformer.
28. The switching power supply circuit according to claim 27. 30. The switching converter means is a separately-excited current resonance type converter, and constant voltage control is performed by changing a switching drive signal based on a DC output voltage obtained at the secondary side of the insulation transformer. 28. The switching power supply circuit according to claim 1, wherein the switching power supply circuit is configured as described above.