JP2003125585A - Power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sharply reduce the noise of a power unit which has the power factor improving function. SOLUTION: A power factor improving converter PFC 5 modulates the ripple voltage appearing in the output voltage to a DC-DC converter 6 to 10 Vp-p or higher, whereby the DC-DC converter 6 changes its oscillation frequency, according to the ripple voltage contained in the DC voltage from the power factor improving converter PFC 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device having a power factor improving function, and more particularly to a power supply device capable of significantly reducing noise.

[0002]

2. Description of the Related Art Conventionally, as a power supply device, as shown in FIG. 18, an active power factor correction converter for inputting an AC power supply and outputting direct current, and a DC output from the active power factor correction converter are input. There is known a DC-DC converter that outputs another direct current.

Now, the operation of the conventional power supply device shown in FIG. 18 will be described. When the AC power supply 1 is applied to the power supply device, the sine wave voltage supplied from the AC power supply 1 passes through the filter 2, is full-wave rectified by the rectifier 3 and passes through the filter 4, and is transmitted to the power factor correction converter PFC5. Wave rectified waveform is provided. At this time, the filters 2 and 4 remove noise components leaking from the power supply device to the AC power supply 1 side.

First, one end of the criticality detection winding 61b is G
It is connected to ND, and the other end is input to the + input terminal of the comparator 54 via the resistor 60, and at the same time, the first reference voltage 53 is input to the − input terminal of the comparator 54. In the comparator 54, both input voltages are compared, and the low level set signal is output from the comparator 54 to the flip-flop 59.

The flip-flop 59 is a comparator 54.
Is set according to the set signal from the switching element 6 and a high level drive signal is output from the Q output terminal.
2 is on-controlled. When the switching element 62 is turned on, the filter 4 moves from the main winding 61a to the switching element 6
2 through the drain-source and the current detection resistor 63
Switching current flows to ND, choke coil 61
Energy is stored in.

At this time, the switching current flowing in the switching element 62 is the source-source of the switching element 62.
A current target value V output from the multiplier 55 in the comparator 56 after being converted into a voltage by the current detection resistor 63 provided between the GNDs and input to the + input terminal of the comparator 56.
compared with m.

When the switching current reaches the current target value Vm, the comparator 56 outputs a high level reset signal to the flip-flop 59. The flip-flop 59 is reset in response to the reset signal from the comparator 56, the high level drive signal output from the Q output terminal is switched to the low level, and the switching element 62 is off-controlled.

When the switching element 62 is turned off, the energy stored in the choke coil 61 and the voltage supplied from the filter 4 are combined, and the rectifying diode 6
4, the output capacitor 65 is charged. As a result, the output capacitor 65 outputs a voltage boosted higher than the peak value of the full-wave rectified waveform supplied from the filter 4.

The voltage from the capacitor 65 is the resistance 66, 6
The voltage is divided by 7 and input to the operational amplifier 57, compared with the second reference voltage 58 by the operational amplifier 57, and this error signal is supplied to the multiplier 55. The full-wave rectified waveform from the filter 4 is divided by the resistors 51 and 52 and input to the multiplier 55. The multiplier 55 multiplies the full-wave rectified waveform and this error signal to obtain the target current value V of the switching current.
m is supplied to the-input terminal of the comparator 56.

Next, when the release of the energy stored in the choke coil 61 is completed, the criticality detection winding 61 is formed.
The voltage of b is inverted. This voltage is compared with the first reference voltage 53 by the comparator 54, and the comparator 54 outputs a low level set signal to the flip-flop 59. As a result, the flip-flop 59 is set according to the set signal from the comparator 54, and the drive signal is input again to the switching element 62 to be turned on. After that, the output voltage of the output capacitor 65 of the power factor correction converter PFC5 is kept constant by repeating such operations. At the same time, the current of the AC power supply 1 has a sinusoidal current waveform that follows the voltage of the AC power supply 1.

[0011]

As described above, in the power supply device having the power factor improving function, the power factor improving converter P is used.
The DC-DC converter 6 is connected to the output side of the FC5. For this reason, two switching power supply circuits are connected in series although they are one power supply device. Each switching power supply circuit handles a large amount of energy and is prone to generate switching noise.

Moreover, in this type of power supply device, since there are two switching power supply circuits, the noise generated by the entire power supply device becomes large. Therefore, many noise countermeasures are taken to comply with the noise standards of each country. There is a need to do.
As measures against individual noises, measures such as adding a filter immediately before the input / output terminal or slowing the switching speed to make the voltage change rate dv / dt gentle are taken.

Since the conventional power supply device has taken such measures against noise, the addition of parts has been a factor of cost increase. At the same time, it causes an increase in switching loss, forcing a decrease in conversion efficiency and an increase in the size of the device.

The present invention has been made in view of the above,
The purpose is to make it possible to significantly reduce noise in a power supply device having a power factor improving function.

[0015]

The invention according to claim 1 is
In order to solve the above problems, a power factor correction converter that inputs an AC power source, converts it into a DC voltage and outputs it, and a DC-DC that converts a DC voltage from this power factor correction converter into another DC voltage and outputs it. A power supply device including a converter, wherein the power factor correction converter has a ripple voltage appearing in an output voltage to the DC-DC converter of 10 Vp-
It is characterized in that the DC-DC converter is provided with a ripple voltage modulating means for modulating the voltage to become p or more, and the oscillation frequency fluctuates according to the ripple voltage included in the DC voltage from the power factor correction converter.

In order to solve the above-mentioned problems, the invention as set forth in claim 2 is a power factor correction converter for inputting a full-wave rectified waveform from an AC power source through a choke coil, turning it on and off by a switching element, and converting it into a DC voltage. And a DC-DC converter that converts the DC voltage from the power factor correction converter into another DC voltage and outputs the converted DC voltage, wherein the power factor correction converter converts the DC voltage to the DC-DC converter. An output signal is extracted, a modulation means for injecting an AC component of the full-wave rectified waveform from the AC power source to generate a modulation waveform, and an error signal composed of a difference between the modulation waveform from the modulation means and a reference voltage Error signal generating means for generating a current target value linked with the full-wave rectified waveform from the full-wave rectified waveform from the AC power supply and the error signal from the error signal generating means. A value generation means, a switching current detection means for detecting a switching current flowing in the ON period of the switching element and outputting it as a current detection value, and a current detection value of the switching current from the switching current detection means is the current target value. OFF control means for turning off the switching element when the current target value from the generation means is reached, and the modulation means includes a ripple voltage of a frequency component of the AC power source that appears in an output voltage to the DC-DC converter. Is generated to be 10 Vp-p or more, and the oscillating frequency of the DC-DC converter varies according to the ripple voltage included in the DC voltage from the power factor correction converter.

In order to solve the above-mentioned problems, a third aspect of the present invention is a power factor correction converter for inputting a full-wave rectified waveform from an AC power source through a choke coil, turning it on and off by a switching element, and converting it into a DC voltage. And a DC-DC converter that converts a DC voltage from the power factor correction converter into another DC voltage and outputs the converted DC voltage, wherein the power factor correction converter has an oscillating waveform having a predetermined frequency. Oscillating means for outputting, a modulating means for extracting an output voltage to the DC-DC converter and injecting an AC component of an oscillating waveform from the oscillating means to generate a modulating waveform, and a modulating waveform from the modulating means. Error signal generating means for generating an error signal composed of the difference between the reference voltage and the reference voltage, a full-wave rectified waveform from the AC power source, and an error signal from the error signal generating means. From the switching current detection means, a current target value generation means for generating a current target value linked with a rectified waveform, a switching current detection means for detecting a switching current flowing in the ON period of the switching element and outputting it as a current detection value, OFF detection means for turning off the switching element when the detected current value of the switching current reaches the current target value from the current target value generation means, and the modulation means supplies to the DC-DC converter. The modulated waveform is generated so that the ripple voltage of the frequency component of the oscillating means appearing in the output voltage becomes 10 Vp-p or more, and the DC-DC converter converts the ripple voltage included in the DC voltage from the power factor correction converter into the ripple voltage. The gist is that the oscillation frequency fluctuates accordingly.

In order to solve the above-mentioned problems, the invention as set forth in claim 4 is a power factor improving converter for inputting a full-wave rectified waveform from an AC power source through a choke coil, turning it on and off by a switching element, and converting it into a DC voltage. And a DC-DC converter that converts a DC voltage from the power factor correction converter into another DC voltage and outputs the converted DC voltage, wherein the power factor correction converter is provided in the choke coil. Set signal generating means for generating a set signal when the ringing voltage generated in the criticality detection winding reaches the first reference voltage, and turning on the switching element in response to the set signal from the set signal generating means. ON control means, and a triangular wave generator which is activated in response to the set signal from the set signal generating means to oscillate a triangular wave signal having a predetermined frequency Means, a modulation means for extracting an output voltage to the DC-DC converter and injecting an AC component of a full-wave rectified waveform from the AC power supply to generate a modulation waveform, a modulation waveform from the modulation means and a reference Error signal generating means for generating an error signal that is interlocked with the full-wave rectified waveform and that has a voltage value of the triangular wave signal from the triangular wave oscillating means reaches the error signal from the error signal amplifying means. And an off control means for turning off the switching element, wherein the modulation means modulates the ripple voltage of the frequency component of the AC power source appearing in the output voltage to the DC-DC converter to 10 Vp-p or more. The oscillating frequency of the DC-DC converter varies according to the ripple voltage included in the DC voltage from the power factor correction converter. .

According to a fifth aspect of the invention, in order to solve the above-mentioned problems, the DC-DC converter is a self-excited oscillation type DC.
The gist is that it is a frequency control type DC-DC converter such as a DC converter, a voltage quasi-resonance type DC-DC converter, a current resonance type DC-DC converter.

In order to solve the above-mentioned problems, a sixth aspect of the present invention has a gist that the DC-DC converter is a DC-DC converter having a frequency modulation function.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a diagram showing a configuration of a power supply device according to a first embodiment of the present invention. The configuration of the power supply device will be described with reference to FIG. In FIG.
A sine wave voltage is supplied from the AC power supply 1 to the filter 2, the sine wave voltage that has passed through the filter 2 is full-wave rectified by the rectifier 3 and passes through the filter 4, and the full-wave rectified waveform from the filter 4 is the power factor. It is supplied to the improved converter PFC5.
The filters 2 and 4 remove noise components leaking from the power supply device to the AC power supply 1 side.

The DC output of the power factor correction converter PFC5 is input to the DC-DC converter 6, and the DC-
The DC converter 6 converts the DC voltage input from the power factor correction converter PFC5 into another DC voltage and outputs it to the output terminal 7
Output from a and 7b. The filters 2 and 4 are shown in FIG.
The π-type normal mode filter shown in FIG. 3, the simplest normal mode filter shown in FIG. 3, the normal mode filter + common mode filter shown in FIG. 4 and the like can be omitted.

Next, the structure of the power factor correction converter PFC5 will be described in detail. Power factor correction converter PFC5
Has a booster chopper circuit as a basic configuration, which includes a main winding 61a of the choke coil 61, a switching element 62, a rectifying diode 64, and an output capacitor 65.

The choke coil 61 is provided with a main winding 61a and a criticality detection winding 61b. Main winding 61a
Is connected to one output terminal of the filter 4 and the resistor 51, and the other end of the main winding 61a is connected to the switching element 6
2 and the anode of the rectifying diode 64. In addition, one end of the criticality detection winding 61b has a resistor 6
It is connected to the + input terminal of the comparator 54 via 0, and the other end of the criticality detection winding 61b is connected to GND. The cathode of the rectifying diode 64 described above is connected to one end of the output capacitor 65 and the input terminal 5 a of the DC-DC converter 6.

Next, the structure of the control system of the power factor correction converter PFC5 will be described. The + input terminal of the comparator 54 is connected to the GN via the resistor 60 and the criticality detection winding 61b.
Connected to D. The first reference voltage 53 is input to the-input terminal of the comparator 54. The comparator 54 compares both input voltages, and when the voltage generated in the criticality detection winding 61b input to the + input terminal is lower than the first reference voltage 53, a low level set signal is flip-flopted. It is output to the set terminal of the switch 59.

The set input terminal of the flip-flop 59 is connected to the output terminal of the comparator 54, the reset input terminal is connected to the output terminal of the comparator 56, and the Q output terminal is connected to the switching element 62. The gate terminal of is connected. The flip-flop 59 outputs a high level drive signal to the Q output terminal when a low level set signal is input from the comparator 54. When a high level reset signal is input from the comparator 56, a low level is output to the Q output terminal.

The voltage between the terminals of the capacitor 65 is divided by the resistors 66 and 67 and input to the-input terminal of the operational amplifier 57, and the full-wave rectified waveform output from the filter 4 is input to the resistor 70 and the capacitor 71. Via the-input terminal. Further, the second reference voltage 58 is input to the + input terminal.

At the negative input terminal of the operational amplifier 57, the output voltage of the capacitor 65 is divided by the resistors 66 and 67 and input, and the full-wave rectified waveform output from the filter 4 is input to the resistor 70 and the capacitor 71. Have been entered through. As a result, the AC component of the full-wave rectified waveform is injected into the extracted divided voltage value of the output voltage to generate the modulated waveform. In the operational amplifier 57, the modulation waveform and the second reference voltage 5
The error signal consisting of the difference from 8 is calculated and supplied to the multiplier 55.

A voltage obtained by dividing the full-wave rectified waveform from the filter 4 by the resistors 51 and 52 is input to one input terminal of the multiplier 55, and the operational amplifier 57 is input to the other input terminal.
The error signal from is input, the multiplier 55 multiplies the full-wave rectified waveform and this error signal, and the result is supplied to the-input terminal of the comparator 56 as the current target value Vm linked with the full-wave rectified waveform.

The current target value Vm of the switching current is supplied from the multiplier 55 to the-input terminal of the comparator 56, the current detection resistor 63 is connected to the + input terminal of the comparator 56, and the switching element 62 is turned on. The voltage corresponding to the drain-source current during the period is input as the current detection value. When the switching current reaches the current target value Vm linked with the full-wave rectified waveform, the comparator 56 outputs a high-level reset signal to the flip-flop 59.

Next, the operation of the power supply device according to the first embodiment of the present invention will be described. When the AC power supply 1 is applied to the power supply device, the sine wave voltage supplied from the AC power supply 1 passes through the filter 2, is full-wave rectified by the rectifier 3 and passes through the filter 4, and is transmitted to the power factor correction converter PFC5. Wave rectified waveform is provided.

(1) Operation at startup First, the + input terminal of the comparator 54 has a resistor 60,
It is in a state of being connected to GND through the criticality detection winding 61b, and at the same time, the first reference voltage 53 is input to the-input terminal of the comparator 54. In the comparator 54, both input voltages are compared, and the voltage at the + input terminal has a lower potential, so the comparator 54 outputs a low-level set signal to the flip-flop 59.

The flip-flop 59 is provided for the comparator 5
The switching element 62 is set according to the set signal from No. 4, and the high-level drive signal is output from the Q output terminal at timing t1 shown in FIG. When the switching element 62 is turned on, the drain voltage Vd of the switching element 62 drops to near 0 V at timing t1 shown in FIG. Then, a switching current flows from the filter 4 to the GND via the main winding 61a, the drain-source of the switching element 62, and the current detection resistor 63, and energy is stored in the choke coil 61.

At this time, the switching current flowing through the switching element 62 is converted into a voltage Vs by the current detecting resistor 63 provided between the source of the switching element 62 and GND, as shown in FIG.
The full-wave rectified waveform input to the input terminal and output from the multiplier 55 in the comparator 56 is compared with the current target value Vm.

(2) Current target value Vm The output voltage of the capacitor 65 is divided by the resistors 66 and 67 and input to the-input terminal of the operational amplifier 57,
In addition, the full-wave rectified waveform output from the filter 4 is the resistance 7
0, and is input to the minus input terminal of the operational amplifier 57 via the capacitor 71. As a result, the AC component of the full-wave rectified waveform is injected into the extracted divided voltage value of the output voltage to generate the modulated waveform. In the operational amplifier 57, an error signal composed of the difference between the modulated waveform and the second reference voltage 58 is calculated and supplied to the multiplier 55. The waveform B shown in FIG. 6 represents the error signal output from the operational amplifier 57.

At the same time, the full-wave rectified waveform from the filter 4 is divided by the resistors 51 and 52 and input to the multiplier 55. The waveform A shown in FIG. 6 represents a full-wave rectified waveform output from the filter 4, and has a cycle twice the frequency of the commercial power source.

The multiplier 55 generates a voltage obtained by multiplying the error signal from the operational amplifier 57 by the full-wave rectified waveform from the filter 4, and outputs the voltage as the current target value Vm interlocked with the full-wave rectified waveform to the-input terminal of the comparator 56. Supplied.

(3) OFF control of switching element At the timing t2 shown in FIG. 5, the target current value Vm in which the detected current value of the switching current is linked with the full-wave rectified waveform
Then, the comparator 56 outputs a high-level reset signal to the flip-flop 59. The flip-flop 59 is reset in response to the reset signal from the comparator 56, the high level drive signal output from the Q output terminal is switched to the low level, and the switching element 62 is off-controlled. Switching element 62
When is turned off, the energy stored in the choke coil 61 and the voltage supplied from the filter 4 are combined, and the output capacitor 65 is charged through the rectifying diode 64.

As a result, a voltage boosted higher than the peak value of the full-wave rectified waveform supplied from the filter 4 is output to the output capacitor 65. The waveform C shown in FIGS. 7 and 6 is the output terminals 5a, 5 of the power factor correction converter PFC5.
It is a figure which shows the mode of the output voltage between b. As shown in this figure, while the output voltage from the conventional power factor correction converter PFC has no ripple voltage, the output voltage from the power factor correction converter PFC5 in the present embodiment is
A ripple voltage of about 10 Vp-p is modulated.

(4) On-Control of Switching Element Next, when the energy stored in the choke coil 61 is released, a ringing voltage is generated in the criticality detection winding 61b, and the voltage of the criticality detection winding 61b is generated. Is reversed. This voltage is the first reference voltage 53 and the comparator 54.
And the low level set signal is output from the comparator 54 to the flip-flop 59 at the timing t3.

As a result, the flip-flop 59 is set according to the set signal from the comparator 54, and FIG.
At timing t3 shown in (1), the drive signal is input again to the switching element 62 and is turned on.

Thereafter, by repeating such operations,
The output voltage of the output capacitor 65 of the power factor correction converter PFC5 has a ripple voltage and the average voltage is kept constant. At the same time, the current of the AC power supply 1 has a sinusoidal current waveform that follows the voltage of the AC power supply 1.

Next, the effect of the power supply device according to the first embodiment of the present invention will be described. According to the present embodiment, the output voltage of the capacitor 65 is divided by the resistors 66 and 67 and input to the negative input terminal of the operational amplifier 57, and the full-wave rectified waveform output from the filter 4 is the resistance 70. , Of the operational amplifier 57 via the capacitor 71
Since it is input to the input terminal, the negative input terminal of the operational amplifier 57 generates a modulation waveform in which the AC component of the full-wave rectified waveform is injected into the divided voltage value of the extracted output voltage. Then, in the operational amplifier 57, the modulation waveform and the second reference voltage 5
An error signal consisting of the difference from 8 is calculated and supplied to the multiplier 55. In the multiplier 55, a voltage obtained by multiplying the error signal from the operational amplifier 57 and the full-wave rectified waveform from the filter 4 is generated and supplied to the comparator 56 as the current target value Vm linked with the full-wave rectified waveform.

When the detected current value of the switching current reaches the current target value Vm linked with the full-wave rectified waveform, the comparator 56 outputs a high-level reset signal to the flip-flop 59. Since the flip-flop 59 is reset according to the reset signal from the comparator 56 and the switching element 62 is off-controlled, the output voltage ripple is caused by the modulation waveform in which the AC component of the full-wave rectified waveform is injected into the divided value of the output voltage. Can be set to 10 Vp-p or more, and as a result, the following effects appear.

As the DC-DC converter 6, for example, as shown in FIG. 8, a self-excited flyback converter whose switching frequency fluctuates according to the input voltage is used. Since the output voltage of the power factor correction converter PFC5 has the ripple voltage as described above, that is, the input voltage of the DC-DC converter 6 changes, the switching frequency of the DC-DC converter 6 is large. fluctuate. As a result, the frequency components of the noise generated from the DC-DC converter 6 are dispersed without being concentrated at a specific frequency.

By the way, the noise generated from electronic equipment is regulated by the international standard CISPR, and in particular, the bandwidth of the receiver used for noise measurement is determined to be 9 kHz. Therefore, a ripple voltage is generated in the output voltage of the power factor correction converter PFC5,
By changing the input voltage of the DC-DC converter 6, the fluctuation band of the switching frequency of the DC-DC converter 6 can be dispersed to 9 kHz or more, and noise can be significantly reduced.

Application Example 1 FIG. 8 is a diagram showing a self-excited flyback DC-DC converter 16 applicable to the DC-DC converter 6 of the power supply according to the embodiment of the present invention.

Here, the operation of the self-excited flyback DC-DC converter 16 will be described with reference to FIG. Output terminals 5a, 5 of the power factor correction converter PFC5
b is the input terminals 16a, 1 of the DC-DC converter 16
6b, each connected to a power factor correction converter PFC5
Output voltage is the input voltage Vi of the DC-DC converter 16.
Will be supplied.

First, from the input voltage Vi, the starting resistor R6,
A charging current flows through the capacitor C4 through the route of the resistor R7, the capacitor C4, the auxiliary winding P2, and the current detection resistor R3. The voltage of the capacitor C4 is the threshold value Vt of the switching element Q1.
When it reaches h, the switching element Q1 is turned on and a voltage is applied to the primary winding P1. When a voltage is applied to the primary winding P1, a feedback voltage is generated in the auxiliary winding P2 to be added to the voltage of the capacitor C4, and the switching element Q1 is rapidly turned on.

The current in the primary winding P1 rises with the lapse of time, and energy is stored in the transformer T1. The combined value of the voltage detected by the current detection resistor R3 and the bias voltage of the capacitor C3 is Vbe (Vt of the control transistor Q2.
h) When the voltage is reached, the control transistor Q2 is turned on and the switching element Q1 is turned off.

When the switching element Q1 is turned off, the energy stored in the transformer T1 is transferred to the secondary winding S.
Is rectified and smoothed by the diode D21 and the capacitor C21 and output. When the release of the energy stored in the transformer T1 ends, a ringing voltage is generated in each winding of the transformer T1. Then, the ringing voltage generated in the auxiliary winding P2 turns on the switching element Q1 again. After that, the oscillation operation is continued by repeating this operation.

The output voltage Vo is the voltage detection circuit 1 on the secondary side.
7 and the error signal is transmitted to the primary side by the photocoupler PC1. This error signal controls the transistor side of the photocoupler PC1 to adjust the voltage of the capacitor C3. The voltage charged in the capacitor C3 controls the timing at which the switching element Q1 is turned off, and the output voltage becomes constant.

In the DC-DC converter 16, the peculiar oscillation frequency is determined by the winding ratio of the primary winding P1 and the secondary winding S of the transformer T1, the input voltage Vi and the output voltage Vo.

Even in the general self-excited flyback converter, the switching frequency fluctuates by several kHz when the input voltage fluctuates by 10V. Since the bandwidth of the switching frequency is generally about 10 kHz, the bandwidth of the switching frequency is 9 kHz.
It spreads out more and goes out of the band of the filter of the receiver used for noise measurement, and the frequency component of noise can be dispersed outside the band of measurement of this receiver.

Therefore, the DC-DC converter 16 which uses the output voltage of the power factor correction converter PFC5 as the input voltage Vi
In the case of DC-D, since the switching frequency greatly changes according to the fluctuation of the ripple voltage of the input voltage Vi.
The fluctuation band of the switching frequency of the C converter 16 is 9
Since it can be dispersed at a frequency of not less than kHz, a great effect can be obtained in reducing noise.

Application Example 2 FIG. 9 is a diagram showing a voltage quasi-resonant type DC-DC converter 26 applicable to the DC-DC converter 6 of the power supply device according to the embodiment of the present invention. Here, referring to FIG. 9, a voltage quasi-resonant type D
The operation of the C-DC converter 26 will be described.

Output terminal 5 of the power factor correction converter PFC5
a and 5b are input terminals 26 of the DC-DC converter 26.
a and 26b are respectively connected to the power factor improving converter P.
The output voltage of FC5 is supplied as the input voltage Vi of the DC-DC converter 26.

First, the flip-flop FF is set by the pulse output from the oscillator OSC and the switching element Q1 is turned on. When the switching element Q1 turns on, the switching current increases with the passage of time. The switching current is converted into a voltage by the current detection resistor R2, combined with the error signal from the secondary side by the resistor R1 and the capacitor C1, and compared with the reference voltage ES1 by the comparator COMP1.

When the combined value of the switching current and the error signal reaches the reference voltage ES1, the output of the comparator COMP1 becomes high level, the flip-flop FF is reset and the output Q1 is turned off. Flip flop FF
When the output Q1 is turned off, the energy stored in the transformer T1 is rectified and smoothed by the diode D21 and the capacitor C21 from the secondary winding S and output.

When the discharge of the energy stored in the transformer T1 is completed, a ringing voltage is generated in each winding of the transformer T1. The ringing voltage generated in the auxiliary winding P2 is compared with the reference voltage ES2 by the comparator COMP2. That is, the generation of the ringing voltage is detected, the flip-flop FF is set, and the switching element Q1 is turned on again. After that, the oscillation operation is continued by repeating this operation. The output voltage is detected by the voltage detection circuit 27 on the secondary side, and the error signal is transmitted to the primary side by the photocoupler PC1. The transistor side of the photocoupler PC1 is controlled by this error signal and is combined with the detection voltage of the switching current by the resistor R1 and the capacitor C1 to control the off timing of the switching element Q1 and make the output voltage constant.

Also in this DC-DC converter 26, the turn ratio of the primary winding P1 and the secondary winding S of the transformer T1, the input voltage Vi and the output voltage Vo, and the transformer T1.
The intrinsic oscillation frequency is determined by the quasi-resonant frequency due to the inductance L of 1 and the capacitor C2. Therefore, in the DC-DC converter 26 that uses the output voltage of the power factor correction converter PFC5 as the input voltage Vi, the switching frequency greatly changes according to the fluctuation of the ripple voltage of the input voltage Vi, and thus the DC-DC converter 26.
The fluctuation band of the switching frequency can be dispersed to 9 kHz or more, and a great effect can be obtained in noise reduction.

Application Example 3 FIG. 10 is a DC-DC converter 36 having a frequency modulation function applicable to the DC-DC converter 6 of the power supply device according to one embodiment of the present invention.
FIG.

Here, the operation of the DC-DC converter 36 having a frequency modulation function will be described with reference to FIG. The output terminal 5a of the power factor correction converter PFC5,
5b is an input terminal 36a of the DC-DC converter 36,
Power factor correction converter PFC connected to 36b
The output voltage of 5 is the input voltage V of the DC-DC converter 36.
i is supplied.

First, the ON timing of the switching element Q1 is always determined by the pulse output from the oscillator OSC. When the switching element Q1 turns on, the switching current increases with the passage of time. The switching current is converted into a voltage by the current detection resistor R6 and compared with the error signal from the secondary side by the comparator COMP1.

When the switching current reaches the value of this error signal, the output of COMP1 becomes high level, the flip-flop FF is reset and Q1 is turned off. When the switching element Q1 is turned off, the energy stored in the transformer T1 is transferred from the secondary winding S to the diode D2.
1, rectified and smoothed by the capacitor C21 and output. Eventually, the switching element Q1 is turned on again by the output of the oscillator OSC regardless of whether or not all the energy stored in the transformer T1 has been discharged.

The oscillation frequency of the DC-DC converter 36 is determined by the charge / discharge cycle of the capacitor C1. The capacitor C1 is charged by a current flowing from the reference voltage ES2 through the resistor R2 and an input voltage Vi from the resistor R1.
Is determined by the current flowing through. Generally, the current ratio of the resistor R2 is set high, and the charging cycle is mainly determined by the resistor R2. The capacitor C1 is discharged by the oscillator OS.
It is performed by the discharge circuit inside C. Where input voltage V
When i changes, the current of the resistor R1 also changes, and the charging cycle slightly changes. Therefore, when the input voltage Vi changes, the oscillation frequency changes depending on the ratio of the resistors R1 and R2.

Therefore, the DC-DC converter 36 having the input voltage Vi as the output voltage of the power factor correction converter PFC5
In the case of DC-D, since the switching frequency greatly changes according to the fluctuation of the ripple voltage of the input voltage Vi.
The fluctuation band of the switching frequency of the C converter 36 is set to 9
Since it can be dispersed at a frequency of not less than kHz, a great effect can be obtained in reducing noise.

Application Example 4 FIG. 11 is a diagram showing a current resonance type DC-DC converter 46 applicable to the DC-DC converter 6 of the power supply device according to the embodiment of the present invention. Here, referring to FIG. 11, a current resonance type DC-
The operation of the DC converter 46 will be described.

Output terminal 5 of power factor correction converter PFC5
a and 5b are input terminals 46 of the DC-DC converter 46.
a and 46b respectively connected to the power factor improving converter P
The output voltage of FC5 is supplied as the input voltage Vi of the DC-DC converter 46.

The switching elements Q1 and Q2 are alternately turned on and off with a dead time provided by the two gate control signals output from the control circuit 47. The leakage inductance Lr of the transformer T1 and the capacitor C are turned on by being alternately turned on by the switching elements Q1 and Q2.
A resonance current due to 3 flows.

At the same time, an exciting current flows through the inductance Lp1 of the primary winding P1 of the transformer T1. This exciting current charges and discharges the capacitor C3 regardless of the load current.
In order to adjust the output voltage, it is necessary to change the amplitude voltage of the capacitor C3 by controlling the charging / discharging of the capacitor C3 by this exciting current. These are switching elements Q1,
This is possible by varying the oscillation frequency of Q2 that is turned on and off alternately, and the output voltage can be adjusted by so-called frequency control.

Now, this DC- which makes the output voltage a constant voltage
In the DC converter 46, when the load is constant, its oscillation frequency is also constant. Also, when the input voltage changes, the oscillation frequency fluctuates and the output voltage is made constant.

Therefore, the DC-DC converter 46 having the input voltage Vi as the output voltage of the power factor correction converter PFC5
In the case of DC-D, since the switching frequency greatly changes according to the fluctuation of the ripple voltage of the input voltage Vi.
The fluctuation band of the switching frequency of the C converter 46 is set to 9
Since it can be dispersed at a frequency of not less than kHz, a great effect can be obtained in reducing noise.

(Second Embodiment) FIG. 12 is a diagram showing a configuration of a power supply device according to a second embodiment of the present invention. The configuration of the power supply device will be described with reference to FIG. The feature of this embodiment is that the operational amplifier 57 has a −
After the full-wave rectified waveform output from the filter 4 is divided by the resistors 51 and 52 with respect to the input terminal, the resistor 70,
It is input to the-input terminal via the capacitor 71. Further, the voltage between the terminals of the capacitor 65 is divided by the resistors 66 and 67 and input to the negative input terminal. Further, the second reference voltage 58 is input to the + input terminal.

Next, a characteristic portion of the operation of the power supply device according to the second embodiment of the present invention will be described, and first operation will be described.
The description of the same parts as those in the embodiment will be omitted. (1) Operation at startup Since the operation is similar to that of the first embodiment, the description thereof will be omitted.

(2) Current target value Vm The output voltage of the capacitor 65 is divided by the resistors 66 and 67 and input to the-input terminal of the operational amplifier 57,
In addition, the full-wave rectified waveform output from the filter 4 is the resistance 5
After being divided by 1, 52, resistor 70, capacitor 7
It is input to the-input terminal of the operational amplifier 57 via 1.

As a result, an AC component of the full-wave rectified waveform is injected into the extracted divided voltage value of the output voltage to generate a modulated waveform. In the operational amplifier 57, an error signal composed of the difference between the modulated waveform and the second reference voltage 58 is calculated and supplied to the multiplier 55.

The waveform B shown in FIG. 6 corresponds to the operational amplifier 5
7 shows the error signal output from No. 7. At the same time, the full-wave rectified waveform from the filter 4 is divided by the resistors 51 and 52 and input to the multiplier 55. The waveform A shown in FIG. 6 represents a full-wave rectified waveform output from the filter 4, and has a cycle twice the frequency of the commercial power source.

In the multiplier 55, a voltage obtained by multiplying the error signal from the operational amplifier 57 and the full-wave rectified waveform from the filter 4 is generated, and is input to the-input terminal of the comparator 56 as the current target value Vm linked with the full-wave rectified waveform. Supplied.

(3) OFF control of switching element,
(4) Since the ON control of the switching element is the same as that of the first embodiment, the description thereof will be omitted. Next, the effect of the power supply device according to the second embodiment of the present invention, (Application Example 1) to (Application Example 4) is the same, and thus the description thereof is omitted.

(Third Embodiment) FIG. 13 is a diagram showing a configuration of a power supply device according to a third embodiment of the present invention. The configuration of the power supply device will be described with reference to FIG. The feature of this embodiment is that the operational amplifier 57 has a −
The voltage between the terminals of the capacitor 65 is divided by the resistors 66 and 67 and input to the input terminal.

Further, the full-wave rectified waveform output from the filter 4 is applied to the resistor 5 with respect to the + input terminal of the operational amplifier 57.
After being divided by 1, 52, resistor 70, capacitor 7
It is input via 1. Further, the second input via the resistor 72 that serves as an impedance for injecting the full-wave rectified waveform to the + input terminal of the operational amplifier 57.
The reference voltage 58 is input.

Next, a characteristic portion of the operation of the power supply device according to the third embodiment of the present invention will be described, and first operation will be described.
The description of the same parts as those in the embodiment will be omitted. (1) Operation at startup Since the operation is similar to that of the first embodiment, the description thereof will be omitted.

(2) Target current value Vm The output voltage of the capacitor 65 is divided by the resistors 66 and 67 and input to the-input terminal of the operational amplifier 57.
In addition, the full-wave rectified waveform output from the filter 4 is the resistance 5
After being divided by 1, 52, resistor 70, capacitor 7
1 is input to the + input terminal of the operational amplifier 57, and at the same time, the second reference voltage 58 is input to the + input terminal via the resistor 72.

As a result, in the operational amplifier 57, an error having a modulation waveform formed by the difference between the divided voltage value of the output voltage and the second reference voltage 58 which is a modulation waveform obtained by injecting the AC component of the full-wave rectified waveform. The signal is calculated and supplied to the multiplier 55.

The multiplier 55 generates a voltage obtained by multiplying the error signal having the modulation waveform from the operational amplifier 57 by the full-wave rectified waveform from the filter 4, and generates a voltage as a current target value Vm linked with the full-wave rectified waveform. -Supplied to the input terminals.

(3) OFF control of switching element,
(4) Since the ON control of the switching element is the same as that of the first embodiment, the description thereof will be omitted. Next, the effect of the power supply device according to the third embodiment of the present invention, (Application Example 1) to (Application Example 4) is the same, and thus the description thereof is omitted.

(Fourth Embodiment) FIG. 14 is a diagram showing the structure of a power supply device according to a fourth embodiment of the present invention. The configuration of the power supply device will be described with reference to FIG. The feature of this embodiment is that the operational amplifier 57 has a −
The AC waveform output from the filter 2 is input to the-input terminal via the resistor 70 and the capacitor 71 with respect to the input terminal. Further, the voltage between the terminals of the capacitor 65 is divided by the resistors 66 and 67 and input to the negative input terminal. Further, the second reference voltage 58 is input to the + input terminal.

Next, a characteristic portion of the operation of the power supply device according to the fourth embodiment of the present invention will be described, and first operation will be described.
The description of the same parts as those in the embodiment will be omitted. (1) Operation at startup Since the operation is similar to that of the first embodiment, the description thereof will be omitted.

(2) Current target value Vm The output voltage of the capacitor 65 is divided by the resistors 66 and 67 and input to the-input terminal of the operational amplifier 57,
Moreover, the AC waveform output from the filter 2 is the resistance 70,
It is input to the-input terminal of the operational amplifier 57 via the capacitor 71.

As a result, the AC component of the AC waveform is injected into the extracted divided voltage value of the output voltage to generate the modulated waveform. In the operational amplifier 57, the modulation waveform and the second reference voltage 5
An error signal consisting of the difference from 8 is calculated and supplied to the multiplier 55.

In the multiplier 55, a voltage obtained by multiplying the error signal from the operational amplifier 57 and the full-wave rectified waveform from the filter 4 is generated, and is input to the-input terminal of the comparator 56 as the current target value Vm linked with the full-wave rectified waveform. Supplied.

(3) OFF control of switching element,
(4) Since the ON control of the switching element is the same as that of the first embodiment, the description thereof will be omitted. Next, the effect of the power supply device according to the fourth embodiment of the present invention, (Application Example 1) to (Application Example 4) is the same, and thus the description thereof is omitted.

(Fifth Embodiment) FIG. 15 is a diagram showing the structure of a power supply device according to a fifth embodiment of the present invention. The configuration of the power supply device will be described with reference to FIG. The feature of the present embodiment is that an oscillator 73 capable of oscillating any one of a sine wave, a triangular wave, a sawtooth wave, etc. as an output waveform is provided, and an output waveform output from the oscillator 73 is passed through a resistor 70 and a capacitor 71. It is input to the-input terminal of the operational amplifier 57. Also, this-
The voltage between the terminals of the capacitor 65 is divided by the resistors 66 and 67 and input to the input terminal. Further, the second reference voltage 5 is applied to the + input terminal of the operational amplifier 57.
8 has been entered. The frequency of the oscillator 73 is a frequency at which the control operation of the circuit components such as the operational amplifier 57, the multiplier 55, the comparator 56 and the DC-DC converter 6 can follow even when the frequency output from the oscillator 73 changes. If Next, a characteristic part of the operation of the power supply device according to the fifth embodiment of the present invention will be described, and description of the same parts as those in the first embodiment will be omitted.

(1) Operation at startup Since the operation is the same as that of the first embodiment, its explanation is omitted.

(2) Current target value Vm The output voltage of the capacitor 65 is divided by the resistors 66 and 67 and input to the-input terminal of the operational amplifier 57,
Moreover, the output waveform output from the oscillator 73 is the resistance 70,
It is input to the-input terminal of the operational amplifier 57 via the capacitor 71.

As a result, the AC component of the output waveform from the oscillator 73 is injected into the extracted divided voltage value of the output voltage to generate the modulated waveform. In the operational amplifier 57, an error signal composed of the difference between the modulated waveform and the second reference voltage 58 is calculated and supplied to the multiplier 55.

At the same time, the full-wave rectified waveform from the filter 4 is divided by the resistors 51 and 52 and input to the multiplier 55.

In the multiplier 55, a voltage obtained by multiplying the error signal from the operational amplifier 57 and the full-wave rectified waveform from the filter 4 is generated, and is supplied to the-input terminal of the comparator 56 as the current target value Vm linked with the full-wave rectified waveform. Supplied.

(3) OFF control of switching element,
(4) Since the ON control of the switching element is the same as that of the first embodiment, the description thereof will be omitted. Next, the effect of the power supply device according to the fifth embodiment of the present invention, (Application Example 1) to (Application Example 4) is the same, and thus the description thereof is omitted.

(Sixth Embodiment) FIG. 16 is a diagram showing the structure of a power supply device according to a sixth embodiment of the present invention. The configuration of the power supply device will be described with reference to FIG. In the first to fifth embodiments, referring to FIGS. 1, 12, 13, 14, and 15, respectively, the set signal of the flip-flop 59 indicates that the energy stored in the choke coil 61 is released. When the process is completed, the voltage of the criticality detection winding 61b is inverted. That is, FIG. 1, FIG. 12, FIG. 13, FIG. 14, and FIG. 15 are the power factor correction converter PFC in the discontinuous current mode, and the current flowing through the choke coil 61 is reduced to zero.

On the other hand, the feature of the sixth embodiment is that the power factor correction converter PF in the continuous current mode is used.
This is to input the rectangular wave output from the oscillator 81 to the flip-flop 59 as a set signal. That is, every time the rectangular wave output from the oscillator 81 becomes low level, the set signal is flip-flop 59.
Is input to the choke coil 61, the current flowing in the choke coil 61 continuously flows without decreasing to zero.

It is to be noted that FIG. 16 differs from FIG. 1 used in the first embodiment in that the output from the oscillator 81 is input to the flip-flop 59 as a set signal. 12 and 1 used in the fifth embodiment.
3, FIG. 14 and FIG. 15 may be modified so that the output from the oscillator 81 is input to the flip-flop 59 as a set signal.

Regarding the operation of the power supply device according to the sixth embodiment of the present invention, for example, a rectangular wave output from the oscillator 81 is input to the flip-flop 59 as a set signal, and the high level is output from the Q output terminal. Since the drive signal is output and the switching element 62 is ON-controlled, and other operations are the same as those in the first to fifth embodiments, and therefore description thereof will be omitted.

Further, since the same effects can be obtained by the power supply device according to the sixth embodiment of the present invention as in (Application Example 1) to (Application Example 4), the description thereof will be omitted.

(Seventh Embodiment) FIG. 17 is a diagram showing the structure of a power supply device according to a seventh embodiment of the present invention. The configuration of the power supply device will be described with reference to FIG. The feature of the seventh embodiment is that the power factor correction converter PF using a triangular wave current that does not change the width of the ON period of the switching element 62 within a half cycle of the frequency of the AC power supply 1.
A feedback circuit is formed in the booster type power factor correction converter PFC by using a control circuit that operates in the quasi-resonant type voltage mode.

That is, the multiplier 55 and the current detection resistor 63 provided in the first embodiment are deleted,
Further, a triangular wave oscillator 8 that oscillates a triangular wave by being triggered according to the set signal output from the comparator 54
5 and the reset signal is flip-flop 5 when the voltage value of the amplified error signal output from the operational amplifier 57 reaches the voltage value of the triangular wave output from the triangular wave oscillator 85.
This is because the comparator 56 for outputting to 9 is provided.

The voltage value of the error signal after amplification output from the operational amplifier 57 is substantially constant for at least a half cycle of the frequency of the AC power supply 1 because the response is sufficiently delayed by the capacitor 93.

Here, the inductance value (L value) of the choke coil 61 is selected so that the current flowing through the choke coil 61 is always a triangular wave, and the feedback response time is set to a half cycle or more of the frequency of the AC power supply. so,
The width of the ON period of the switching element 62 within the half cycle is substantially fixed.

Further, since the width of the ON period of the switching element 62 is fixed, the switching current Ip becomes
By fixing T and L,

[Equation 1] Ip = E × T / L (1) A value proportional to the input voltage E is determined.

Therefore, the current flowing through the choke coil 61 is filled with the triangular wave having an ascending slope and the triangular wave having a descending slope, so that 1/2 of the peak current becomes the input current. That is, the sine wave current waveform is proportional to the input current waveform. Next, the operation of the power supply device according to the seventh embodiment of the present invention will be described.

When the AC power supply 1 is applied to the power supply device, the sine wave voltage supplied from the AC power supply 1 passes through the filter 2, is full-wave rectified by the rectifier 3 and passes through the filter 4, and the power factor improving converter The full-wave rectified waveform is supplied to the PFC 5.

(1) Operation at Startup First, the + input terminal of the comparator 54 has the resistor 60,
It is in a state of being connected to GND through the criticality detection winding 61b, and at the same time, the first reference voltage 53 is input to the-input terminal of the comparator 54. In the comparator 54, both input voltages are compared, and the voltage at the + input terminal has a lower potential, so the comparator 54 outputs a low-level set signal to the flip-flop 59.

The flip-flop 59 is provided for the comparator 5
The switching element 62 is set according to the set signal from No. 4, and the high-level drive signal is output from the Q output terminal at timing t1 shown in FIG.

When the switching element 62 is turned on, FIG.
As shown at timing t1 in FIG.
Drain voltage Vd of the device drops to near 0V. Then, a switching current flows from the filter 4 to the GND via the main winding 61a and the drain-source of the switching element 62, and energy is stored in the choke coil 61.

(2) The output voltage of the error signal capacitor 65 is divided by the resistors 66 and 67 and input to the-input terminal of the operational amplifier 57.
In addition, the full-wave rectified waveform output from the filter 4 is the resistance 7
0, and is input to the + input terminal of the operational amplifier 57 via the capacitor 71. At the same time, the second reference voltage 58 is input to the + input terminal via the resistor 72. As a result,
The amplified output of the operational amplifier 57 becomes a divided voltage value of the output voltage and a modulated waveform in which the AC component of the full-wave rectified waveform is injected, and is supplied to the-input terminal of the comparator 56.

(3) When the low level set signal is output from the comparator 54 to the flip-flop 59 at the time of starting the OFF control of the switching element, at the same time, the set signal is input to the triangular wave oscillator 85 to trigger and generate a triangular wave. Is oscillated. The triangular wave output from the triangular wave oscillator 85 is input to the + input terminal of the comparator 56. In the triangular wave oscillator 85, the comparator 5
4 to the next set signal is input, for example, about 10
It oscillates a triangular wave at a frequency of 0 kHz.

In the comparator 56, the voltage value of the amplified error signal output from the operational amplifier 57 is the triangular wave oscillator 8
When the voltage value of the triangular wave output from 5 is reached, a reset signal is output to the flip-flop 59. The flip-flop 59 is reset in response to the reset signal from the comparator 56, the high-level drive signal output from the Q output terminal is switched to the low level, and the switching element 62 is off-controlled.

When the switching element 62 is turned off, the energy stored in the choke coil 61 and the voltage supplied from the filter 4 are combined, and the rectifying diode 6
4, the output capacitor 65 is charged.

As a result, a voltage boosted higher than the peak value of the full-wave rectified waveform supplied from the filter 4 is output to the output capacitor 65. FIG. 7 is a diagram showing a state of the output voltage between the output terminals 5a and 5b of the power factor correction converter PFC5. As shown in this figure, the output voltage from the conventional power factor correction converter PFC has no ripple voltage, whereas the output voltage from the power factor correction converter PFC5 in the present embodiment is approximately 10 Vp-p. It has a ripple voltage.

(4) ON Control of Switching Element Next, when the energy stored in the choke coil 61 is released, a ringing voltage is generated in the criticality detection winding 61b and the voltage of the criticality detection winding 61b is generated. Is reversed. This voltage is the first reference voltage 53 and the comparator 54.
And a low level set signal is output from the comparator 54 to the flip-flop 59.

As a result, the flip-flop 59 is set according to the set signal from the comparator 54, and the drive signal is input to the switching element 62 again to be turned on. At the same time, the set signal is input to the triangular wave oscillator 85 and a trigger is applied to synchronize the oscillation of the triangular wave with the set signal.

(5) Feedback Response Time In this embodiment, the capacitor 93 for adjusting the response time is connected between the − input terminal and the output terminal of the operational amplifier 57. As a result, the amplified error signal output from the operational amplifier 57 responds slowly to the output voltage of the capacitor 65 due to the capacitor 93, and thus has a substantially constant value over a half cycle of the frequency of the AC power supply 1. Become.

On the other hand, the + input terminal of the operational amplifier 57 is
The full-wave rectified waveform output from the filter 4 is input via the resistor 70 and the capacitor 71, and at the same time, the second reference voltage 58 is input via the resistor 72. As a result, the AC component of the full-wave rectified waveform is injected into the reference voltage 58 and slightly superposed on the amplified error signal of the operational amplifier 57. The injection amount of the AC component to these full-wave rectified waveforms is set to such a small level that the ripple voltage appearing in the output voltage of the capacitor 65 is 10 Vp-p or more.

As described above, the injection amount of the AC component into the full-wave rectified waveform is extremely small in the error signal. The width of the ON period of the switching element 62 is almost fixed.

Further, since the width of the ON period of the switching element 62 is fixed, the switching current Ip becomes
Since T and L are fixed, a value proportional to the input voltage E is determined by the above equation (1). As a result, the current flowing through the choke coil 61 is filled with a rising triangle wave and a descending triangle wave, so that half of the peak current becomes the input current, and the sinusoidal current waveform is proportional to the input current waveform.

As a result, a large ripple voltage is generated in the output voltage of the power factor correction converter PFC5 as compared with the conventional power supply device.

Thereafter, by repeating such operations,
The output voltage of the output capacitor 65 of the power factor correction converter PFC5 has a ripple voltage and the average voltage is kept constant. At the same time, the current of the AC power supply 1 has a sinusoidal current waveform that follows the voltage of the AC power supply 1.

[0129]

As described above, according to the present invention, since a large ripple voltage of 10 Vp-p or more, which is twice the frequency of the commercial power supply, is generated in the output voltage of the power factor correction converter, it is supplied. DC- whose frequency changes with the power supply voltage
The switching frequency of the DC converter is also frequency-modulated according to these ripple voltages. Therefore, DC-
The noise level at the switching frequency of the DC converter is dispersed by the frequency modulation, and the noise level can be significantly reduced.

[Brief description of drawings]

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

FIG. 2 is a circuit of a π-type normal mode filter applicable to filters 2 and 4.

FIG. 3 is a circuit of a normal mode filter applicable to filters 2 and 4.

FIG. 4 is a circuit of a normal mode filter + common mode filter applicable to filters 2 and 4.

FIG. 5 is a timing chart for explaining the operation of the power factor correction converter PFC5.

FIG. 6 is waveforms A, B, and C at various places for explaining the operation of the power factor correction converter PFC5.

FIG. 7 is a waveform for explaining the operation of the power factor correction converter PFC5.

8 is a circuit of a self-excited flyback DC-DC converter 16 applicable to the DC-DC converter 6. FIG.

9 is a circuit of a voltage quasi-resonant type DC-DC converter 26 applicable to the DC-DC converter 6. FIG.

10 is a circuit of a DC-DC converter 36 having a frequency modulation function applicable to the DC-DC converter 6. FIG.

11 is a circuit of a current resonance type DC-DC converter 46 applicable to the DC-DC converter 6. FIG.

FIG. 12 is a diagram showing a configuration of a power supply device according to a second embodiment of the present invention.

FIG. 13 is a diagram showing a configuration of a power supply device according to a third embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of a power supply device according to a fourth embodiment of the present invention.

FIG. 15 is a diagram showing a configuration of a power supply device according to a fifth embodiment of the present invention.

FIG. 16 is a diagram showing a configuration of a power supply device according to a sixth embodiment of the present invention.

FIG. 17 is a diagram showing a configuration of a power supply device according to a seventh embodiment of the present invention.

FIG. 18 is a circuit diagram of a conventional power supply device.

[Explanation of symbols]

1 AC power supply 2,4 filter 3 rectifier 5 Power factor improvement converter PFC 6 DC-DC converter 54, 56 comparator 55 multiplier 59 flip flops 57 operational amplifier 61 choke coil 62 switching element 64 rectifier diode 65 Output capacitor 66,67,70,72 resistance 71,93 capacitors 73,81 oscillator 85 Triangle wave oscillator

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H006 AA02 CA02 CA07 CB08 CC02                       DA04 DB01 DC05                 5H730 AA02 AA18 BB43 BB52 BB57                       BB62 BB72 BB86 CC03 CC04                       DD04 EE02 EE03 EE07 EE59                       FD01 FG07 VV03 VV06

Claims (6)

[Claims] 1. A power factor correction converter which inputs an AC power source and converts it into a DC voltage and outputs it, and a D which converts a DC voltage from this power factor correction converter into another DC voltage and outputs it.
A power supply device including a C-DC converter, wherein the power factor correction converter includes ripple voltage modulation means for modulating the ripple voltage appearing in the output voltage to the DC-DC converter to be 10 Vp-p or more. The power supply device, wherein the DC-DC converter has an oscillation frequency that varies according to a ripple voltage included in the DC voltage from the power factor correction converter. 2. A power factor correction converter for inputting a full-wave rectified waveform from an AC power source through a choke coil, turning it on and off by a switching element to convert it into a DC voltage, and a DC voltage from this power factor correction converter. And a DC-DC converter that converts the DC voltage into a DC voltage and outputs the DC voltage, the power factor improving converter extracts an output voltage to the DC-DC converter to extract a full wave from the AC power supply. Modulation means for injecting an AC component of the rectified waveform to generate a modulation waveform, error signal generation means for generating an error signal composed of a difference between the modulation waveform from the modulation means and a reference voltage, and all of the AC power supplies. Current target value generating means for generating a current target value linked with the full-wave rectified waveform from the wave rectified waveform and the error signal from the error signal generating means, and turning on the switching element. A switching current detection unit that detects a switching current flowing during a period and outputs it as a current detection value, and a current detection value of the switching current from the switching current detection unit has reached a current target value from the current target value generation unit. An OFF control means for turning off the switching element at times is provided, and the modulation means modulates the ripple voltage of the frequency component of the AC power source appearing in the output voltage to the DC-DC converter to 10 Vp-p or more. A power supply device that generates a waveform, wherein the DC-DC converter has an oscillation frequency that varies according to a ripple voltage included in the DC voltage from the power factor correction converter. 3. A power factor correction converter for inputting a full-wave rectified waveform from an AC power source through a choke coil, turning it on and off by a switching element and converting it into a DC voltage, and a DC voltage from this power factor correction converter. And a DC-DC converter for converting and outputting the DC voltage to the DC-DC converter, wherein the power factor correction converter includes an oscillating unit that outputs an oscillating waveform having a predetermined frequency, and the DC-DC converter. Of the output voltage of the oscillating means to inject an AC component of the oscillating waveform from the oscillating means to generate a modulating waveform, and an error signal composed of a difference between the modulating waveform from the modulating means and a reference voltage. An error signal generating means, a full-wave rectified waveform from the AC power supply, and an error signal from the error signal generating means generate a current target value linked with the full-wave rectified waveform. Current target value generating means, a switching current detecting means for detecting a switching current flowing in the ON period of the switching element and outputting it as a current detection value, and a current detection value of the switching current from the switching current detecting means is the current. OFF control means for turning off the switching element when the current target value from the target value generation means is reached, and the modulation means includes a frequency component of the oscillation means that appears in an output voltage to the DC-DC converter. A modulation waveform is generated such that the ripple voltage is 10 Vp-p or more, and the DC-DC converter has an oscillation frequency that varies according to the ripple voltage included in the DC voltage from the power factor correction converter. Power supply. 4. A power factor correction converter for inputting a full-wave rectified waveform from an AC power supply through a choke coil, turning it on and off by a switching element to convert it into a DC voltage, and a DC voltage from this power factor correction converter. And a DC-DC converter for converting the DC voltage into a DC voltage and outputting the converted DC voltage, wherein the power factor correction converter has a first ringing voltage generated in a criticality detection winding provided in the choke coil. Set signal generating means for generating a set signal when reaching the reference voltage, ON control means for turning on the switching element in response to the set signal from the set signal generating means, and set from the set signal generating means Triangular wave oscillating means for activating in response to a signal to oscillate a triangular wave signal having a predetermined frequency, and output to the DC-DC converter A full-wave rectified waveform composed of a modulation means for extracting a voltage and injecting an AC component of the full-wave rectified waveform from the AC power source to generate a modulated waveform, and a difference between the modulated waveform from the modulation means and a reference voltage. Error signal generating means for generating an interlocked error signal, and off control means for turning off the switching element when the voltage value of the triangular wave signal from the triangular wave oscillating means reaches the error signal from the error signal amplifying means. Wherein the modulation means generates a modulation waveform so that a ripple voltage of a frequency component of the AC power source appearing in an output voltage to the DC-DC converter becomes 10 Vp-p or more, and the DC-DC converter, A power supply device characterized in that an oscillation frequency fluctuates according to a ripple voltage contained in a DC voltage from the power factor correction converter. 5. The DC-DC converter is a self-excited oscillation type DC-DC converter, a voltage quasi-resonant type DC.
5. The power supply device according to claim 1, wherein the power supply device is a frequency control type DC-DC converter such as a -DC converter or a current resonance type DC-DC converter. 6. The power supply device according to claim 1, wherein the DC-DC converter is a DC-DC converter having a frequency modulation function.