JPH06169571A - Switching power supply device - Google Patents

Abstract

PURPOSE:To provide a switching power supply device which can achieve the improvement of power factor synthetically even in the case where a switching power supply without a power factor improving circuit is used jointly. CONSTITUTION:For a power factor improving circuit A, a rectifier circuit 1 rectifies AC input Ei so as to generate rectified output, and a capacitor 2 generates DC output Vo being smoothed based on the rectified output Eo, and a control circuit 3 flattens the fluctuation of an AC input current Ii generated by the instantaneous fluctuation of the DC output Vo. A switching power circuit B generates power output by switching DC output Vo. Output terminals 41 and 42 are connected to the rear stages of a power factor improving circuit A, and lead out the DC output Vo to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply device, and more specifically, it supplies a DC output which has been subjected to power factor correction processing to a switching power supply circuit and outputs the DC output to the outside to output power. The present invention relates to a technique that can achieve power factor improvement even when a switching power supply without a factor improvement circuit is used together.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 3-78469 is known as a prior art of a switching power supply device with improved power factor. The above publication uses a chopper circuit to match the rectified voltage waveform with the current waveform flowing through the chopper circuit to improve the power factor.

[0003]

However, although the conventional switching power supply device discloses means for achieving its own power factor correction, it is also possible to use a switching power supply without a power factor correction circuit in combination. Does not disclose any means by which the power factor improvement can be achieved. Therefore, in order to improve the power factor, it is necessary to use all new power supply equipment, and existing power supply equipment cannot be effectively used.

Therefore, an object of the present invention is to solve the above-mentioned problems and to supply the DC output which has been subjected to the power factor correction processing to the switching power supply circuit and to derive the DC output to the outside to thereby obtain the power factor. It is an object of the present invention to provide a switching power supply device capable of achieving a comprehensive power factor improvement even when a switching power supply having no improvement circuit is used together.

[0005]

In order to solve the above problems, the present invention provides a switching power supply device including a power factor correction circuit, a switching power supply circuit, and an output terminal.
The power factor correction circuit includes a rectifier circuit, a capacitor, and a control circuit, the rectifier circuit rectifies an AC input to generate a rectified output, and the capacitor generates a DC output smoothed based on the rectified output. The control circuit flattens the fluctuation of the AC input current caused by the instantaneous fluctuation of the DC output, and the switching power supply circuit switches the DC output to generate a power supply output. The terminal is connected to a subsequent stage of the power factor correction circuit and leads the DC output to the outside.

[0006]

In the power factor correction circuit, the rectifier circuit rectifies an AC input to generate a rectified output, the capacitor generates a DC output smoothed based on the rectified output, and the control circuit generates an AC input current caused by an instantaneous fluctuation of the DC output. Since the fluctuation of is flattened,
Distortion of the AC input current is reduced and power factor improvement is achieved.

Since the switching power supply circuit switches the DC output to generate the power supply output, a desired DC voltage or AC voltage can be obtained.

Since the output terminal is connected to the subsequent stage of the power factor correction circuit and leads the DC output to the outside, the non-power factor correction switching power supply is connected by connecting the switching power supply without the power factor correction circuit. Overall power factor improvement including the above can be achieved.

[0009]

1 is a block diagram showing the configuration of a first embodiment of a switching power supply device according to the present invention. The figure shows a switching power supply with three-phase alternating current as the AC input.
Is a power factor correction circuit, B is a switching power supply circuit, C is a non-power factor correction switching power supply without a power factor correction circuit, 4
Reference numerals 1 and 42 are output terminals.

The power factor correction circuit A includes a rectifier circuit 1, a capacitor 2 and a control circuit 3. The rectifier circuit 1 rectifies the AC inputs Ea, Eb, Ec and outputs a rectified output Eo. Specifically, it is composed of a three-phase full-wave rectifier circuit. The capacitor 2 outputs a DC output Vo that is smoothed based on the rectified output Eo. DC output Vo is applied to terminals 21 and 2.
2 to the switching power supply circuit B. The control circuit 3 flattens the fluctuations of the AC input currents Ia, Ib, Ic caused by the instantaneous fluctuations of the DC output Vo during switching. The control circuit 3 is composed of an inductor element 31.

The switching power supply circuit B switches the DC output Vo to generate a DC or AC power supply output. For example, a DC-DC converter can be used to obtain a DC power supply output, and a DC-AC converter can be used to obtain an AC power supply output. The switching power supply circuit B outputs the DC output Vo, for example, from several kHz to several hundreds of kHz.
Switching at a frequency of Hz.

The output terminals 41 and 42 are connected to the terminals 21 and 22 in the subsequent stage of the power factor correction circuit A and lead the DC output Vo to the outside.

As described above, in the power factor correction circuit A, the rectifier circuit 1 rectifies the AC inputs Ea, Eb, Ec to generate the rectified output Eo, and the capacitor 2 smoothes the DC output Vo based on the rectified output Eo. And the switching power supply circuit B is
Since the DC output Vo is switched, the DC output Vo is changed according to the energy transmitted to the switching power supply circuit B.
Is reduced. At this time, the charging current Id flows from the rectifier circuit 1 to the capacitor 2. Since the inductor element 31 suppresses the charging current Id by the inertial action, it flattens the fluctuations of the AC input currents Ia, Ib, Ic caused by the instantaneous fluctuations of the DC output Vo. Moreover, since the ripple of the rectified output Eo is small, the fluctuation of the charging current Id is small. Therefore, distortion of the AC input currents Ia, Ib, and Ic is reduced, and power factor improvement is achieved.

Since the switching power supply circuit B switches the DC output Vo to generate a power supply output, a desired DC voltage or AC voltage can be obtained.

Since the output terminals 41 and 42 are connected to the subsequent stage of the power factor correction circuit A and lead the DC output Vo to the outside, the switching power supply C having no power factor correction circuit is provided.
By connecting to the non-power factor improving switching power supply C
A comprehensive power factor improvement including can be achieved.

FIG. 2 is a block diagram showing the configuration of the second embodiment of the power factor correction circuit constituting the switching power supply device according to the present invention. In the figure, 1 is a rectifier circuit, 3 is a control circuit, 5 is a first power conversion circuit, and 6 is a second power conversion circuit.

The rectifier circuit 1 is a circuit that rectifies an AC input Ei to obtain a rectified output Eo, and can be constituted by a general full-wave rectifier circuit.

The first power conversion circuit 5 includes a first inductor element 51, a first switch element 52, and a first output circuit 53. First inductor element 51
Are connected in series to the first switch element 52 and the rectifier circuit 1. The first inductor element 51 stores the energy supplied from the rectifier circuit 1 during the ON period of the first switch element 52 and transfers the energy to the first output circuit 53 during the OFF period. The first switch element 52 is
It can be composed of a field effect transistor or the like. The first output circuit 53 converts the transmission energy into the first DC output V1. The first output circuit 53 has a diode 531 and a capacitor 532. The diode 531 transmits the unidirectional energy transmitted from the first inductor element 51 to the capacitor 532. Capacitor 532 stores the unidirectional energy and produces a first DC output V1.

The second power conversion circuit 6 includes a second inductor element 61, a second switch element 62, and a second output circuit 63. The embodiment has a well-known flyback converter configuration. The second inductor element 61 is connected in series with the second switch element 62 and the first output circuit 53. The second inductor element 61 transmits the switching output based on the first DC output V1 to the second output circuit 63. The second switch element 62 can be composed of a field effect transistor or the like. The second output circuit 63 converts the switching output into the DC output Vo.

The control circuit 3 receives the input signal S1 corresponding to the DC output Vo and outputs a control signal S2 having a pulse width for keeping the DC output Vo constant to the first switch element 52 and the second switch element 62. To do. In the figure, the first switch element 52 is shared by the second switch element 62. The input signal S1 is a signal obtained by dividing the DC output Vo. The control signal S2 is a signal whose frequency is constant and whose pulse width when turned on changes. The frequency is set to several kHz to several hundred kHz.

FIG. 3 is a diagram showing the waveform of the input current of the power factor correction circuit according to the second embodiment. In the figure, Ii is an AC input current, Io is a rectified output current, Eo is a rectified output, S
2 is a control signal. Hereinafter, referring to FIG. 2, FIG.
Will be explained together with the action.

As described above, the first power conversion circuit 5
Means that the first inductor element 51 is the first switch element 5
2 and the rectifier circuit 1, and the first switch element 52
The energy supplied from the rectifier circuit 1 is accumulated during the on period Ton of the above, and the energy is transmitted to the first output circuit 53 during the off period Toff, and the first output circuit 53 transmits the transmitted energy to the first DC output V1. The control circuit 3 outputs to the first switch element 52 a control signal S2 having a pulse width that keeps the DC output Vo constant. Therefore, the control circuit 3 responds to the instantaneous value of the rectified output current Io for each pulse. Energy is transferred from the first inductor element 51 to the first output circuit 53.

A specific description will be given by paying attention to the pulse of reference numeral a. When the first switch element 52 is turned on, the rectified output current Ioa represented by the equation (1) flows through the first inductor element 51 due to a transient phenomenon.

Ioa = Eoa * Ton / L1 (1) Eoa: Instantaneous value of rectified output when the first switch element is turned off Ton: On time of pulse L1: Inductance of the first inductor element At this time Energy PL1 represented by the equation (2) is stored in the first inductor element 51. PL1 = (Eoa * Ton) ² / (2 * L1) (2) The stored energy PL1 becomes a so-called flyback voltage during the off period Toff of the first switch element 52, and the stored energy PL1 is supplied to the first output circuit 53. Is transmitted. The rectified output current Ioa is
The characteristic that the tail is drawn by the inertial action of the first inductor element 51 is shown. When the load connected to the second output circuit 63 becomes heavy and a large current flows, the ON time Ton of the control signal S2 becomes longer, and more stored energy PL1 is transmitted. The same applies to other pulses. Usually, since a filter circuit (not shown) is provided before and after the rectifying circuit 1, the AC input current Ii is an average value of the rectifying output current Io.

Therefore, even if the rectified output Eo is smaller than the DC output Vo, the AC input current Ii flows dispersedly for each pulse, and the envelope of the current is similar to the waveform of the rectified output Eo. Therefore, the distortion of the AC input current Ii is reduced and the power factor is improved.

In the second power conversion circuit 6, the second inductor element 61 is connected to the second switch element 62 and the first output circuit 53, and the switching output based on the first DC output V1 is output to the second output. Is transmitted to the second output circuit 63, and the second output circuit 63 converts the switching output into the direct current output Vo. The control circuit 3 outputs the control signal S2 having a pulse width that makes the direct current output Vo a constant voltage. Switch element 62
Therefore, the DC output Vo is controlled to a constant voltage.

Since the first switch element 52 and the second switch element 62 are driven in synchronization, the energy transferred from the first output circuit 53 to the second power conversion circuit 6 is the first inductor element. It is replenished by the energy transmission from 51, and the decrease of the first DC output V1 is prevented.
Further, the capacity of the capacitor 532 can be small.

Further, in the embodiment, the first inductor element 51 is a transformer, the input winding 511 is connected to the first switch element 52 and the rectifying circuit 1, and the output winding 512 is connected.
Are connected to the first output circuit 53. Output winding 51
2, the first switch element 52 is turned on and the input winding 51
When the rectified output current Io flows through 1, a positive voltage is generated in the direction of the black circle. When the first switch element 52 is turned off, the flyback voltage Vf1 is generated in the reverse direction. The flyback voltage Vf1 serves as an energy source for the first output circuit 53.

The second inductor element 61 is composed of a transformer, and the input winding 611 is connected to the second switch element 62 and the first switch element 62.
Connected to the output circuit 53 of the second switch element 62 and stores the energy supplied from the first output circuit 53 during the ON period of the second switch element 62, and the output winding 612 is connected to the second switch element 6
Energy is transmitted to the second output circuit 63 as a switching output during the OFF period of 2. Second output circuit 63
Has a diode 631 and a capacitor 632,
A flyback converter is configured with the output winding 611. The capacitor 632 is equivalent to the capacitor 2 in the embodiment of FIG. Second inductor element 61
Generates a flyback voltage Vf2 and transfers the energy to the second output circuit 63, similarly to the first inductor element 51. Since the first switch element 52 and the second switch element 62 are driven in synchronization with the control signal S2,
Energy transfer from the second inductor element 61 to the second output circuit 63, and transfer of energy from the first inductor element 51 to the first
Energy transmission to the output circuit 53 is performed in synchronization. Therefore, in the first output circuit 53, the energy released to the second inductor element 61 is replenished from the first inductor element 51 at the same timing.

Energy EL1 stored in the input winding 511 of the first inductor element 51 during the on period Ton of the first switch element 52 and the second inductor during the on period Ton of the second switch element 62. Input winding 6 of element 61
The energy EL2 stored in 11 is equal. Specifically, when the average value Eav of the rectified output Eo, the inductance of the input winding 511 is L1, and the inductance of the input winding 611 is L2, (Eav * Ton) ² / (2 * L1) = (V1 * The inductances L1 and L2 of the input windings 511 and 611 are set so that Ton) ² / (2 * L2) (3). As a result, the energy balance in the first output circuit 53 is maintained and the first DC output V1 is made constant.

The first power conversion circuit 5 includes a first diode.
It has a cord 54. In the first diode 54, the anode is connected to the input winding 511 of the first inductor element 51 and the cathode is connected to the connection point between the second inductor element 61 and the second switch element 62, The reverse flow of the first DC output V1 is blocked. That is, when the flyback voltage generated in the input winding 611 is higher than the flyback voltage generated in the input winding 511, backflow is blocked. On the contrary, if the flyback voltage generated on the input winding 511 is higher than the flyback voltage generated on the input winding 611, then the first diode 54 is connected to the second diode 54 as indicated by the dotted line in FIG. By providing the power conversion circuit 6, it is possible to prevent the backflow from the first power conversion circuit 5.

The first power conversion circuit 5 includes a second diode.
It has a do 55. The first output circuit 53 has a capacitor 532 at the output end. Second diode 55
The anode is connected to the positive side of the rectifier circuit 1, the cathode is connected to the capacitor 532,
A charging circuit for charging the. As a result, the capacitor 532 is charged early when the power is started, and a stable DC output Vo can be obtained quickly.

The second diode 55 has a capacitor 532 when the rectified output Eo is larger than the first DC output V1.
A charging current Id is passed through. Therefore, the capacitor 532 is
When the power supply is started up, both the first inductor element 51 and the second diode 55 are charged. After power on,
When the energy transfer from the first inductor element 51 is insufficient and the first DC output V1 drops, the second diode
Charged from the battery 55. The AC input current Ii is added to the current IL1 flowing through the first inductor element 51 by the second diode.
The charging current Id of the battery 55 is superimposed. As a result, the starting characteristic of the power supply is improved, the distortion of the AC input current Ii is reduced, and the power factor can be improved.

The energy EL1 stored in the input winding 511 of the first inductor element 51 during the ON period Ton of the first switch element 52 is changed to the second inductor during the ON period Ton of the second switch element 62. Input winding 6 of element 61
It is equal to or smaller than the energy EL2 stored in 11. Specifically, when the average value Eav of the rectified output Eo, the inductance of the input winding 511 is L1, and the inductance of the input winding 611 is L2, (Eav * Ton) ² / (2 * L1) = (V1 * Ton) ² / (2 * L2) ・ (4) or (Eav * Ton) ² / (2 * L1)> (V1 * Ton) ² / (2 * L2) ・ (5) The inductances L1 and L2 of the input windings 511 and 611 are set.

As a result, when the expression (4) is satisfied,
After the capacitor 532 is charged at the time of starting the power supply, the charged charge of the capacitor 532 is maintained by the energy transfer from the first inductor element 51, and the second diode 55.
Since the charging current Id due to is eliminated, the starting characteristic can be improved and the waveform distortion of the AC input current can be reduced most.
When the expression (5) is satisfied, the first inductor element 51
The charging current Id by the second diode 55 flows only when the energy transmitted from the
It is possible to prevent excessive charging of 32.

The second power conversion circuit 6 may be a DC-DC converter, and may be a forward type or resonance type converter.

FIG. 4 is a block diagram showing the configuration of a third embodiment of the power factor correction circuit constituting the switching power supply device according to the present invention. In the figure, 1 is a rectifier circuit, 3 is a control circuit, and 7 is a booster circuit.

The rectifying circuit 1 rectifies the AC input Ei to generate a rectified output Eo.

The booster circuit 7 is a circuit for generating a DC output Vo by boosting the rectified output Eo. The booster circuit 7 includes a switching element 71, an inductor 72, and a diode 73.
And a capacitor 74. The switching element 71 is connected in series with the inductor 72 and the rectifier circuit 1 and is driven on / off in the range of several kHz to several hundred kHz. In this embodiment, it is set to 50 kHz. The diode 73 and the capacitor 74 are connected in series, both ends of the series connection circuit are connected in parallel to the switching element 71, and the DC output Vo is obtained from both ends of the capacitor 74. The capacitor 74 is equivalent to the capacitor 2 in the embodiment of FIG.

The control circuit 3 includes a rectified output Eo and a booster circuit 7.
It is controlled so that the currents flowing in the same phase. The control circuit 3 includes a target setting circuit 33, an error detection circuit 34, a current detection circuit 35, a differential amplifier circuit 36, and a pulse width control circuit 37.

The target setting circuit 33 includes a reference voltage signal generating section 330, receives the rectified output voltage signal S3 and the DC output voltage signal S4, and outputs the first output signal S5 and the second output signal S6. Is output. Reference voltage signal generator 330
Generates a reference voltage signal S50. First output signal S
5 is obtained from the reference voltage signal S50. The second output signal S6 is obtained from the DC output voltage signal S4. One of the first output signal S5 and the second output signal S6 changes so that the DC output Vo becomes higher than the rectified output Eo by following the increase and decrease in the entire voltage range of the rectified output Eo. FIG. 5 is a characteristic diagram showing an example of the first output signal S5. The first output signal S5 follows the rectified output voltage signal S3,
The DC output Vo is set to be larger than the rectified output Eo. The same applies to the second output signal S6.

The error detection circuit 34 outputs the first output signal S
5, the second output signal S6 and the rectified output voltage signal S3 are input, the first output signal S5 and the second output signal S6 are compared, and the error detection signal S7 having a similar waveform to the rectified output voltage signal S3. Is being output. Specifically, the error amplification circuit 342 compares the first output signal S5 and the second output signal S6 and outputs the error signal S8, and the multiplication circuit 344 outputs the error signal S8 and the rectified output voltage signal S3. The error detection signal S7 is obtained by multiplication. Error amplification circuit 342, multiplication circuit 3
Reference numeral 44 can be composed of a differential amplifier circuit using an operational amplifier, a multiplication circuit, or the like.

The current detection circuit 35 detects the current flowing through the inductor 72 and outputs the current detection signal S9.

The differential amplifier circuit 36 receives the error detection signal S7 and the current detection signal S9, compares the two signals, and outputs a differential signal S10 that causes the current detection signal S9 to follow the error detection signal S7.

The pulse width control circuit 37 controls the differential signal S10.
Is input to supply the control signal S11 for controlling the switching element 71 so as to minimize the differential signal S10 to the switching element 71.

As described above, in the booster circuit 7, the switching element 71 is driven on / off at the frequency f2 higher than the frequency f1 of the AC power source 10, the inductor 72 is connected in series with the switching element 71, and the series connection thereof is performed. Both ends of the circuit are connected to the output terminals 11 and 12 of the rectifier circuit 1, a diode 73 and a capacitor 74 are connected in series, and both ends of the series connection circuit are connected in parallel to the switching element 71, and both ends of the capacitor 74 are connected. Since the direct current output Vo is obtained from the switching element 71, the energy stored in the inductor 72 when the switching element 71 is turned on becomes the flyback voltage Vf when the switching element 71 is turned off.
The flyback voltage Vf is superimposed on the rectified output Eo, and a DC output Vo higher than the rectified output Eo is obtained.

The target setting circuit 33 uses the reference voltage signal S50.
A rectified output voltage signal S3 and a DC output voltage signal S4 are input, and a first output signal S5 and a second output signal S6 are output. Output signal S5 is obtained from the reference voltage signal S50, the second output signal S6 is obtained from the DC output voltage signal S4, and one of the first output signal S5 and the second output signal S6 is rectified and output. The increase / decrease in the entire voltage range of Eo is followed, and the DC output Vo is changed to be higher than the rectified output Eo, and the error detection circuit 34 causes the first output signal S5, the second output signal S6, and the rectified output. Since the voltage signal S3 is input and the first output signal S5 and the second output signal S6 are compared and the error detection signal S7 having a similar waveform to the rectified output voltage signal S3 is output, the reference voltage signal S3 is changed. If you let the second Force signal S6 is first output signal S5
The DC output Vo also changes at the same time. When the DC output voltage signal S4 is changed, the second output signal S6 is controlled to match the first output signal S5, and the DC output Vo changes in the process of matching. This satisfies the requirement that the DC output Vo is higher than the rectified output Eo, which is the requirement for power factor improvement.

The current detection circuit 35 detects the current flowing through the inductor 72 and outputs the current detection signal S9, and the differential amplifier circuit 36 outputs the error detection signal S7 and the current detection signal S9.
And a differential signal S10 that causes the current detection signal S9 to follow the error detection signal S7 is output, and the pulse width control circuit 3
7 supplies the control signal 371 for controlling the switching element 71 so as to minimize the differential signal S10 to the switching element 71, the DC output Vo has a voltage corresponding to the first output signal S5. In addition, the input current changes following the AC input voltage, becomes equal to a resistance load when viewed from the AC power supply 10, and the power factor can be improved.

As a result, when the rectified output Eo drops, the DC output Vo also drops, so that the current flowing through the switching element 71 for boosting can be reduced, and the power loss of the switching element 71 is reduced. can do.

The target setting circuit 33 uses the rectified output voltage signal S
3 can be configured to change the DC output voltage signal S4. FIG. 6 is a circuit diagram showing a specific example of the target setting circuit in that case. In the figure, the same reference numerals as those in FIG. 4 denote the same components. Below, FIG.
Also, description will be made with reference to FIG. Reference numeral 330 is a reference voltage signal generator, and 334 is a DC output voltage adjuster. Terminal 3
The rectified output Eo is applied between the terminal 35 and the terminal 336, and the DC output Vo is applied between the terminal 337 and the terminal 336.

The reference voltage signal generator 330 outputs the DC output V
A reference voltage Vk serving as a reference for increasing or decreasing o is generated and output as a first output signal S5. Reference voltage Vk is battery B
It is gained by 1. The positive electrode of the battery B1 is connected to the terminal 338. The reference voltage Vk may be obtained by forming a DC constant voltage circuit and dividing the DC constant voltage with a resistance voltage dividing circuit.

The DC output voltage adjusting section 334 changes the voltage division ratio of the resistor for dividing the DC output Vo according to the rectified output voltage signal S3, and outputs the divided voltage as the second output signal S6. In this embodiment, a diode D1 and a capacitor C
1, resistors R1 to R6, operational amplifier IC1, battery B2
And have. The diode D1 and the capacitor C1 are connected in series, and both ends of which are connected in series are connected to the terminal 335 and the terminal 336. A resistor R1 and a resistor R2 are connected in series, and both ends of which are connected in series are a capacitor C1.
It is connected to the. The connection point between the resistors R1 and R2 is connected to the negative input terminal of the operational amplifier IC1, and the rectified output Eo
Is supplied to the operational amplifier IC1. The battery B2 is connected to the positive input terminal of the operational amplifier IC1 and supplies the reference voltage Vk to the operational amplifier IC1. The resistor R3 is connected between the output terminal and the negative input terminal of the operational amplifier IC1. The resistor R4 has one end connected to the output end of the operational amplifier IC1 and the other end connected to a connection point between the resistors R5 and R6. Resistance R5 and resistance R6
Are connected in series, and both ends connected in series are connected to the terminal 337 and the terminal 336. The connection point between the resistors R5 and R6 is connected to the terminal 339, and the divided voltage VR6 obtained by dividing the DC output Vo is supplied as the second output signal S6. The operational amplifier IC1 constitutes an inverting amplifier circuit,
As shown in FIG. 7, the output voltage Vout decreases as the divided voltage Vin increases. Therefore, the terminal voltage V of the resistor R5
When the rectified output Eo increases, that is, when the output voltage Vout decreases, R5 increases due to an increase in the current flowing through the resistor R4. The terminal voltage VR5 of the resistor R5 is the rectified output Eo.
Decreases, that is, the output voltage Vout increases, it decreases due to the decrease in the current flowing through the resistor R4. Therefore, the divided voltage VR6 of the resistor R6 decreases as the terminal voltage VR5 increases and increases as the terminal voltage VR5 decreases if the DC output Vo is constant.

The error detection circuit 34 connected in the subsequent stage has the divided voltage VR6 at the terminal 339 and the reference voltage Vk at the terminal 338.
Since they operate so as to match with each other, the change in the divided voltage VR6 substantially changes the first output signal S5, and the DC output Vo is finally adjusted to the target DC output voltage. That is, when the rectified output Eo increases, the divided voltage VR6 decreases, the DC output Vo increases in the process of making the divided voltage VR6 equal to the reference voltage Vk, and when the rectified output Eo decreases, the divided voltage VR6. Rises, and the DC output Vo is lowered in the process of making the divided voltage VR6 equal to the reference voltage Vk.
As a result, the DC output Vo is adjusted to be higher than the rectified output Eo, and it is possible to obtain the same effect as that of the embodiment shown in FIG.

The target setting circuit 33 uses the rectified output voltage signal S
It is also possible to change the reference voltage signal S3 according to 3. FIG. 8 is a circuit diagram showing a specific example of the target output voltage setting circuit. In the figure, the same reference numerals as those in FIGS. 4 and 6 denote the same components. Less than,
This will be described with reference to FIGS. 4, 6 and 8.

The reference voltage signal generator 330 changes the reference voltage Vk according to the rectified output voltage signal S3 and outputs the first output signal S5. In this embodiment, the diode D1
And a capacitor C1, a resistor R1 and a resistor R2, a resistor R7, a battery B3, a resistor R5 and a resistor R6. The diode D1, the resistor R1 and the resistor R2 are connected in series, and both ends of the series connection circuit are connected to the terminals 335 and 336. The capacitor C1 is connected in parallel to the series connection circuit of the resistor R1 and the resistor R2. Resistance R
2 generates a divided voltage Vin obtained by dividing the rectified output Eo. The resistor R7 and the battery B3 are connected in series, and both ends of which are connected in series are connected to the resistor R2. One end of the resistor R7 is connected to the terminal 338, and the reference voltage Vk is applied to the terminal 338.
Is being supplied. The reference voltage Vk becomes a voltage as shown in FIG. 9 from the relationship between the divided voltage Vin and the voltage Vref of the battery B3. That is, when the divided voltage Vin is higher than the voltage Vref, current flows from the resistor R1 to the battery B3 and becomes higher than the voltage Vref, and the divided voltage Vin is the voltage Vr.
When it is lower than ef, current flows from the battery B3 to the resistor R2 and becomes lower than the voltage Vref.

The DC output voltage adjusting section 334 has resistors R5 and R6 and divides the DC output Vo by resistance.
The connection point of the resistors R5 and R6 is connected to the terminal 339, and the divided voltage VR6 is applied to the terminal 339 as the second output signal S6.
Output as.

Since the error detection circuit 34 connected in the subsequent stage operates so as to match the first output signal S5 and the second output signal S6, the second output signal S6 is changed to the first output signal S5. The DC output Vo is finally adjusted to the target DC output voltage. As a result, it is possible to obtain the same effects as the embodiment of FIG.

[0058]

As described above, according to the present invention, the following effects can be obtained. (A) In the power factor correction circuit, a rectifier circuit rectifies an AC input to generate a rectified output, a capacitor generates a DC output smoothed based on the rectified output, and a control circuit generates an AC input current caused by an instantaneous fluctuation of the DC output. It is possible to provide a switching power supply device capable of achieving power factor improvement because the fluctuations in the power supply are flattened. (B) Since the switching power supply circuit switches the DC output to generate the power supply output, it is possible to provide the switching power supply device that can obtain the desired power supply output while improving the power factor. (C) The output terminal is connected to the latter stage of the power factor correction circuit and leads the DC output to the outside. Therefore, by connecting the switching power supply without the power factor correction circuit, the non-power factor correction switching power supply is connected. It is possible to provide a switching power supply device that can achieve comprehensive power factor improvement including the above.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a switching power supply device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a second embodiment of a power factor correction circuit.

FIG. 3 is a diagram showing a waveform of an input current of the power factor correction circuit according to the second embodiment.

FIG. 4 is a block diagram showing a configuration of a third embodiment of a power factor correction circuit.

FIG. 5 is a characteristic diagram showing an example of a first output signal.

FIG. 6 is a circuit diagram showing a specific example of a target setting circuit configured to change a DC output voltage signal.

FIG. 7 is a characteristic diagram of an inverting amplifier circuit.

FIG. 8 is a circuit diagram showing a specific example of a target setting circuit configured to change a DC output voltage signal.

FIG. 9 is an input / output characteristic diagram of a reference voltage generator.

[Explanation of symbols]

 A Power factor correction circuit 1 Rectifier circuit 1 2 Capacitor 3 Control circuit B Switching power supply circuit C Non-power factor correction switching power supply 41, 42 Output terminal Ei AC input Eo Rectified output Vo DC output

Claims (6)

[Claims] 1. A switching power supply device including a power factor correction circuit, a switching power supply circuit, and an output terminal, wherein the power factor correction circuit includes a rectifier circuit, a capacitor, and a control circuit. A circuit rectifies the AC input to produce a rectified output, the capacitor produces a smoothed DC output based on the rectified output, and the control circuit flattens variations in the AC input current caused by instantaneous variations in the DC output. The switching power supply circuit is for switching the DC output to generate a power supply output, the output terminal is connected to a subsequent stage of the power factor correction circuit,
A switching power supply device for deriving the DC output to the outside. 2. The power factor correction circuit receives a three-phase alternating current, the control circuit has an inductor element, and the inductor element is provided between the rectifier circuit and the capacitor. The switching power supply device according to. 3. The power factor correction circuit includes a first power conversion circuit and a second power conversion circuit, and the first power conversion circuit includes a first inductor element,
A first switch element and a first output circuit, wherein the first inductor element is connected to the first switch element and the rectifier circuit, and the first switch element is connected to the rectifier circuit during the ON period of the first switch element. Energy stored in a rectifier circuit is stored, the energy is transmitted to the first output circuit during an off period, and the first output circuit converts the transmitted energy into a first DC output; The second power conversion circuit includes a second inductor element,
A second switch element and a second output circuit are included, the second inductor element is connected to the second switch element and the first output circuit, and switching based on the first DC output is performed. Transmitting the output to the second output circuit,
The second output circuit is for converting the switching output into the DC output, and the control circuit is input with an input signal according to the DC output, and has a pulse width control signal for keeping the DC output constant. Is output to the first switch element and the second switch element. 4. The first inductor element is a transformer, an input winding is connected to the first switch element and the rectifier circuit, and an output winding is connected to the first output circuit. The second inductor element is a transformer, the input winding is connected to the second switch element and the first output circuit, and the first output circuit is in the ON period of the second switch element. Energy is supplied from the output winding, the output winding is connected to the second output circuit, and the energy is transmitted to the second output circuit as the switching output during the off period of the second switch element. Energy stored in the input winding of the first inductor element during the on period of the first switch element is equal to the energy stored in the second inductor element during the on period of the second switch element. The switching power supply according to the input winding equals the stored as energy in the line, or from less going on claim 3. 5. The first power conversion circuit includes a first diode and a second diode, the first switch element sharing the second switch element, and First
Is connected to the first inductor element to block the reverse flow of the first DC output, the first output circuit has a capacitor at the output end, and the second output circuit The switching power supply according to claim 4, wherein a diode is connected between the rectifier circuit and the capacitor to form a charging circuit for charging the capacitor. 6. A switching power supply device including a power factor correction circuit, a switching power supply circuit, and an output terminal, wherein the power factor correction circuit includes a rectifier circuit, a booster circuit, and a control circuit. A rectifier circuit rectifies an AC input to generate a rectified output, the booster circuit boosts the rectified output to generate a DC output, and the control circuit sets the voltage of the rectified output and a current flowing through the booster circuit in phase. The switching power supply circuit is for switching the DC output to generate a power supply output, the first output terminal is connected to a subsequent stage of the power factor correction circuit, A switching power supply device for deriving the DC output to the outside.