JP2000115999A - Direct-current power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent malfunctions due to high-frequency currents and high-frequency voltages produced on the alternating current input side without degrading the alternating current-to-direct current conversion efficiency of a direct-current power supply. SOLUTION: High-frequency components in a frequency band of 1-2 kHz contained in alternating-current input current IAC from an alternating-current generator 3 are extracted through a band-pass filter circuit 24. A product signal VN obtained from an alternating-current input voltage VAC from the alternating- current generator 3 and a detection signal VD from an error amplifier 22, outputted from a multiplying circuit 23 is compared with a detection signal V2 from an input current detector 19 at a comparator 25. The resultant comparison output signal VP is inputted, together with an output signal VB from the band-pass filter circuit 24, to a subtracting circuit 27. According to a difference signal VDF from the subtracting circuit 27, MOS-FET's 11 and 12 are on/off- controlled. Thus, malfunctions due to high-frequency current IN and high-frequency voltage VN produced on the alternating current input side can be prevented without degrading the alternating current-to-direct current conversion efficiency of a direct-current power supply 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply having a power factor improving function, and more particularly to a DC power supply capable of preventing a malfunction caused by a high-frequency current and a high-frequency voltage generated on an AC input side without lowering the AC-DC conversion efficiency. Belongs to.

[0002]

2. Description of the Related Art 50 or 60 Hz commercial AC power
In order to obtain the power flow, a die that has been
A capacitor consisting of a rectifier such as an diode and a smoothing capacitor
The maximum value of the sinusoidal AC input current is
Since charging current flows to the smoothing capacitor only near
Conduction angle of force current waveform is narrow, and input power factor is as low as around 0.6
There was a problem. Therefore, at least one MOS-
It has a switching element such as an FET, and has an output voltage and commercial
According to the input voltage and input current supplied from the AC power supply
By controlling the switching element on and off with
Converts power from commercial AC power to constant-voltage DC power
With the input voltage supplied from the commercial AC power supply.
DC power supply that increases the input power factor to 1.0 in proportion to the flow
The device has been proposed and put into practical use. Figure 5 shows the engine
And a power source 1 such as an electric motor connected via a joint 2.
AC power supplied from the flow generator 3 to a DC power supply
4 converts the power into constant-voltage DC power and supplies it to the load 5
1 shows a system. Input terminal of DC power supply 4 and power source 1
Between the input voltage V of the DC power supply 4_ACDepending on the power
A control means 6 for controlling the number of revolutions of the source 1 is provided.
Input voltage V of DC power supply 4_ACAccording to the alternator
3 is controlled. In the system shown in FIG.
Is supplied to the DC power supply 4 for some reason, for example.
Input current I_ACExceeds the normal value and the input voltage V _ACFell
In this case, the power source is controlled by a control signal output from the control means 6.
1 increases, thereby generating power of the AC generator 3.
Pressure rises. On the other hand, the output voltage V of the DC power supply 4_DCIs
So that it decreases as the voltage of the generator 3 rises
Constant voltage control is performed. At the same time, the alternator 3
Current I supplied to the power supply 4_ACIs the input voltage V_AC
Is controlled in proportion to.

[0003]

By the way, when the DC power supply 4 is operated by the system shown in FIG. 5 when the power generation capacity of the AC generator 3 is small, the control system of the AC generator 3 and the DC power supply 4 is controlled. delay of signal transmission in the oscillation phenomenon at a frequency input current I _AC and the input voltage V _AC phases of the DC power supply device 4 is substantially in phase occurs. Thereby, the high-frequency current I _N shown in FIG.
Flows, and at the same time, the high-frequency voltage V _N shown in FIG. 6B is also generated, so that the DC power supply 4 may malfunction. Therefore, in the conventional connecting a damper circuit 9 consisting of a capacitor 7 and a resistor 8 connected in series as shown in FIG. 7 between the input terminal of the DC power supply 4, high frequency current I _N via a damper circuit 9 Thus, the high-frequency current _IN and the high-frequency voltage _VN are reduced, and malfunction of the DC power supply 4 is prevented. This method has the advantage of reducing the high-frequency current I _N and a high frequency voltage V _N by the damper circuit 9 having a simple circuit configuration, since the power loss occurs in the resistance 8, AC DC power supply 4 - DC conversion efficiency However, there was a drawback that was reduced. Further, since a relatively large current flows through the damper circuit 9, it is necessary to use a large-capacity capacitor 7 and a resistor 8, and there is a problem that the DC power supply 4 becomes large.

Accordingly, an object of the present invention is to provide a DC power supply device capable of preventing a malfunction caused by a high-frequency current and a high-frequency voltage generated on the AC input side without lowering the AC-DC conversion efficiency.

[0005]

A DC power supply according to the present invention has at least one switching element, and turns on and off the switching element in accordance with an output voltage, an input voltage supplied from an AC power supply, and an input current. By controlling, the AC power from the AC power supply is converted into DC power of a constant voltage, and the input current is made proportional to the input voltage supplied from the AC power supply. In this DC power supply device, output voltage detection means for detecting a difference between the level of the output voltage and a constant voltage level, multiplication means for outputting a product signal of the input voltage and a detection signal of the output voltage detection means, A filter circuit for extracting a high-frequency component included in the input current or the input voltage; and a subtraction unit for outputting a difference signal between an output signal of the multiplication unit and an output signal of the filter circuit. On / off control of the switching element according to a signal. The difference between the level of the DC output voltage and the constant voltage level is detected by the output voltage detection means, and the detection signal is input to the multiplication means together with the input voltage supplied from the AC power supply, and the input current or input supplied from the AC power supply is input. By extracting a high frequency component included in the voltage by a filter circuit, and inputting the output signal of the filter circuit to the subtraction means together with the product signal of the input voltage from the AC power supply output from the multiplication means and the detection signal of the output voltage detection means. The high-frequency signal having a phase substantially opposite to that of the high-frequency signal included in the output signal of the multiplication means is added to the output signal of the multiplication means, and the high-frequency signal included in the output signal of the multiplication means is removed. Therefore, by performing on / off control of the switching element according to the difference signal between the output signal of the multiplication means and the output signal of the filter circuit output from the subtraction means,
The oscillation phenomenon of the AC input current and the AC input voltage caused by the control delay can be prevented, and the high-frequency current and the high-frequency voltage are not generated on the AC input side. Further, since a damper circuit that generates power loss is not required, malfunction of the DC power supply device due to a high-frequency current and a high-frequency voltage generated on the AC input side can be prevented without lowering the AC-DC conversion efficiency.

In an embodiment of the present invention, input current detecting means for detecting the level of the input current, comparing means for comparing an output signal of the multiplying means and a detection signal of the input current detecting means, and the comparing means Subtraction means for outputting a difference signal between the comparison output signal and the output signal of the filter circuit, and a control signal for forming an on / off control signal to be applied to a control terminal of the switching element in accordance with the output signal of the subtraction means Forming means for controlling on / off of the switching element by an output signal of the control signal forming means. The level of the input current is detected by the input current detection means, the output signal of the multiplication means is compared with the detection signal of the input current detection means by the comparison means, and the difference between the comparison output signal of the comparison means and the output signal of the filter circuit is determined. The operation is performed by the subtraction means, and an on / off control signal formed by the control signal forming means in response to the output signal of the subtraction means is applied to the control terminal of the switching element to perform on / off control of the switching element. It is possible to prevent malfunction due to high-frequency current and high-frequency voltage generated on the AC input side without lowering DC conversion efficiency, and to increase the input power factor to approximately 1.0 by making the AC input current proportional to the AC input voltage. AC-
There is an advantage that the DC conversion efficiency can be further improved.

In another embodiment according to the present invention, a DC power supply is connected between each line of a polyphase AC power supply having three or more phases, and a power supply is generated in each phase without lowering the AC-DC conversion efficiency. There is an advantage that malfunction of the DC power supply device due to high frequency current and high frequency voltage can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a DC power supply according to the present invention will be described below with reference to FIGS. However, in these drawings, substantially the same parts as those shown in FIGS. 5 and 6 are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG. 1, the DC power supply 4 according to the present embodiment
Represents a reactor 10 connected to one output line of the AC generator 3 and first and second switching elements
And the first and second diodes 13 and 14 are bridge-connected and the reactor 1
0, and a switching circuit 15 connected between the other output lines of the AC generator 3, a smoothing capacitor 16 connected between the output terminals of the switching circuit 15, and a DC output voltage _VDC and the _DC power supplied from the AC generator 3. AC input voltage V
_AC and depending on the ac input current I _AC switching circuits 1
5 is provided with a control circuit 17 for controlling on / off of the first and second MOS-FETs 11 and 12 in the first and second MOS-FETs. First and second parasitic diodes 11a and 12a are formed in parallel with the first and second MOS-FETs 11 and 12, respectively. An AC input side of the DC power supply 4 has an input voltage detecting transformer 18 for detecting an _AC input voltage VAC supplied from the AC generator 3, and an AC input current I flowing from the AC generator 3 to the reactor 10. input current detector 19 of the _AC as the input current detecting means for detecting a voltage corresponding to the level of the current I _AC is provided. Furthermore,
On the output side of the DC power supply 4, a DC-DC that converts a DC output voltage V _DC generated at both ends of the smoothing capacitor 16 into a DC output voltage V _O having a different voltage level and supplies it to the load 5
Converter 20 is connected.

The control circuit 17 controls the DC output voltage V_DCStandards of
Reference voltage V as a constant voltage level defining the value_ROccurs
Reference power supply 21 and DC output voltage V_DCAnd reference power supply 21
Reference voltage V_ROutput voltage detection
An error amplifier 22 as a stage and a transformer for detecting an input voltage
18 detection signal V₁And the output signal V of the error amplifier 22_DWith
Product signal V_MMultiplication circuit 23 as multiplication means for outputting
And the AC input current detected by the input current detector 19
I_ACHigh frequency components in the frequency band of 1-2 kHz included in
Band-pass filter circuit 24 that extracts
3 output signal V_MAnd the detection signal V of the input current detector 19_Two
And a comparator 25 as comparing means for comparing
Comparison output signal V_PAnd the band input through the amplifier 26
Output signal V of band-pass filter circuit 24_BAmplified signal V_A
Difference signal V_P-V_A= V_DFAs a subtraction means for outputting
A subtraction circuit 27, the first and second MOS-FETs 11,
Three that specify 12 switching frequencies (20 kHz)
Angle wave signal V_TAnd a subtraction circuit
Output signal V of path 27_DFAnd the triangular wave of the triangular wave oscillation circuit 28
Signal V_TIs compared with the PWM modulation signal V_PWMOutput PW
M comparator 29 and input voltage detection transformer 18
Detection signal V₁High (H) level when the polarity of
Signal V_ThreeAnd outputs a low (L) level when negative.
Signal V_ThreeAnd a positive / negative determination circuit 30 for outputting
30 output signal V_ThreeInverted signal -V_ThreeInverter 3 that outputs
1 and the PWM modulation signal V of the PWM comparator 29_PWM
And the output signal V of the positive / negative determination circuit 30_ThreeInversion signal of logical product with
Signal to the first on / off control signal V_G1Switching as
To the gate terminal of the first MOS-FET 11 in the circuit 15
A first NAND gate 32 for outputting, and a PWM comparator
PWM signal V of data 29 _PWMAnd the inverted signal of inverter 31
No.-V_ThreeSecond on / off control of inverted signal of logical product with
Signal V_G2As the second MOS in the switching circuit 15
-The second NAND gate that outputs to the gate terminal of the FET 12
Port 33. Triangular wave oscillation circuit 28,
PWM comparator 29, positive / negative determination circuit 30, inverter 3
1, the first and second NAND gates 32 and 33 perform subtraction
Output signal V of path 25_DFThe first and second MOS-
1st and 1st given to each gate terminal of FET11,12
2 ON / OFF control signal V_G1, V_G2Forming a control signal
Forming means.

Next, the operation of the DC power supply 4 shown in FIG. 1 when the AC generator 3 having a small power generation capacity is used will be described. When the polarity of the ac input voltage V _AC from the AC generator 3 shown in FIG. 2 (A) is positive, the signal V ₃ of the high level is output from the sign determining circuit 30 in the control circuit 17. Also,
The first on / off control signal V _G1 output from the first NAND gate 32 to the gate terminal of the first MOS-FET 11 in the switching circuit 15 has a low (L) level as shown in FIG. It will be constant. Therefore, the first MOS-FET 11 in the switching circuit 15 is turned off during a positive half cycle of the _AC input voltage VAC from the AC generator 3. At the same time, the second on / off control signal V _G2 shown in FIG. 2C is sent from the second NAND gate 33 to the gate terminal of the second MOS-FET 12 in the switching circuit 15.
Is output, and the second MOS-FET 12 is turned on / off. Conversely, when the polarity of the AC input voltage V _AC from the AC generator 3 shown in FIG. 2 (A) is negative, a low level signal V ₃ is output from the sign determining circuit 30 in the control circuit 17.
2 from the first NAND gate 32 to the gate terminal of the first MOS-FET 11 in the switching circuit 15.
A first on / off control signal V _G1 shown in FIG. Therefore, the first MOS in the switching circuit 15 ac input voltage V _AC from the AC generator 3 is in a negative half cycle
-FET 11 is turned on / off. At the same time,
The second on / off control signal V _G2 output from the second NAND gate 33 to the gate terminal of the second MOS-FET 12 in the switching circuit 15 becomes constant at a low level as shown in FIG. Therefore, the second MOS-FET 12 is turned off.

When the second MOS-FET 12 in the switching circuit 15 is on during the positive half cycle of the _AC input voltage VAC from the AC generator 3 shown in FIG. 2A, the AC generator 3 and the reactor The AC input current I _AC flows from the AC generator 3 to the reactor 10 through the path of the 10, the second MOSFET 12 and the second diode 14, and energy is stored in the reactor 10. When the second MOS-FET 12 changes from the on state to the off state, most of the energy stored in the reactor 10 is discharged through the path of the reactor 10, the first parasitic diode 11a, the smoothing capacitor 16, and the second diode 14. Then, the smoothing capacitor 16 is boosted and charged with the polarity shown. When the first MOS-FET 11 in the switching circuit 15 is in the ON state during the negative half cycle of the _AC input voltage VAC from the AC generator 3 shown in FIG. , An AC input current I _AC flows from the AC generator 3 to the reactor 10 through the path of the diode 13, the first MOS-FET 11, and the reactor 10,
Energy is stored in the reactor 10. First MOS
When the FET 11 changes from the on state to the off state, most of the energy stored in the reactor 10 is discharged through the path of the first diode 13, the smoothing capacitor 16, the second parasitic diode 12a and the reactor 10, and the smoothing capacitor 16 Are boosted and charged with the polarity shown. As described above, the DC output voltage _VDC is output from both ends of the smoothing capacitor 16, and further converted by the DC-DC converter 20 into DC output voltages V _O having different voltage levels and supplied to the load 5.

Output from both ends of the smoothing capacitor 16
DC output voltage V_DCIs the error amplifier 22 in the control circuit 17.
The signal is input to the inverting input terminal (−),
Current output voltage V_DCAnd the base input to the non-inverting input terminal (+)
Reference voltage V of quasi power supply 21_RIs detected.
On the other hand, the high frequency voltage V supplied from the AC generator 3_NIncluding
AC input voltage V_ACIs determined by the input voltage detecting transformer 18.
And the detection signal V₁Is the detection of the error amplifier 22
Signal V_DIs input to the multiplication circuit 23 to detect the input voltage.
Signal V of the transformer 18 for₁And the output of the error amplifier 22
Signal V_DProduct signal V_MIs output from the multiplication circuit 23.
Output signal V of multiplication circuit 23_MIs input to the comparator 25
AC input current I detected by current detector 19_ACInspection
Outgoing signal V_TwoAnd the output signal V_MAnd the detection signal V_Twoof
Comparison output signal V_PIs output from the comparator 25. Also,
High frequency current I_NAC input current I including_ACIs the input current detection
And the detection signal V_TwoIs the band pass type
The AC input voltage V_ACFundamental frequency
(50 or 60 Hz) component is cut off and the frequency of 1-2 kHz
High frequency current I in wavenumber band_NIs extracted. Bandpass type
Output signal V of the filter circuit 24_BIs the ratio through the amplifier 26
Output signal V of the comparator 25_PInput to the subtraction circuit 27
And the comparison output signal V of the comparator 25_PAnd bandpass filter
Output signal V of the filter circuit 24_BAmplified signal V_ADifference signal V
_P-V_A= V_DFIs output from the subtraction circuit 27. Subtraction circuit
27 difference signal V_DFAre three in the PWM comparator 29.
The triangular wave signal V of the square wave oscillation circuit 28_TIs compared with the difference signal
V_DFAnd triangular wave signal V_TIs related to V_DF> V_TLow when
Bell, V_DF<V_TPWM which becomes high level at the time of
Modulation signal V_PWMIs output from the PWM comparator 29.
And one of the first and second NAND gates 32 and 33
Input to the input terminal. At the same time, the first NAND
The other input terminal of the gate 32 has an output of the positive / negative judgment circuit 30.
Force signal V_ThreeIs directly input to the second NAND gate 33
Is connected to the output signal V of the positive / negative judgment circuit 30. _Three
Is input via the inverter 31. Therefore,
AC input voltage V from electric machine 3_ACDuring the positive half cycle
Output signal V of positive / negative determination circuit 30_ThreeWill be at a high level
Thus, the first output output from the first NAND gate 32 is
ON / OFF control signal V_G1Becomes a low level constant. On the other hand,
From the NAND gate 33 of the second, the PWM comparator 29
PWM modulated signal V_PWMIs the second on / off control signal V
_G2Is output as In addition, AC input from AC generator 3
Force voltage V_ACOf the positive / negative judgment circuit 30 during the half cycle in which the polarity of
Output signal V_ThreeBecomes low level, the first NAND gate
PWM modulation signal of PWM comparator 29 from port 32
V_PWMIs the first on / off control signal V_G1Output as
You. On the other hand, the second NAND gate 33 outputs the
2 ON / OFF control signal V_G2Becomes a low level constant. No.
Output from the first and second NAND gates 32 and 33, respectively.
First and second on / off control signals V _G1, V_G2
Are the first MOS-FET 11 and the second MOS-FET 1
2 is provided to each gate terminal of the first MOS-
The FET 11 and the second MOS-FET 12 are AC input power
Pressure V_ACON / OFF control is performed alternately every half cycle. this
The DC output from both ends of the smoothing capacitor 16
Output voltage V_DCIs maintained at a certain level, and
AC input current I flowing from reactor 3 to reactor 10_ACBut
AC input voltage V_ACIs controlled in proportion to In addition,
AC input current I supplied from the electric machine 3_ACHigh circumference included in
Wave current I_NIs extracted by the band-pass filter circuit 24
And the output signal V_BAmplified signal V_ATo the comparator 25
Output signal V_PTogether with the input to the subtraction circuit 27.
The comparison output signal V of the comparator 25_PHigh frequency signal included in
The comparison output signal V_PAdded to
And the comparison output signal V of the comparator 25_PHigh frequency signal included in
The signal is removed. Therefore, the high frequency current I
_NAnd high frequency voltage V_NDoes not occur.

In the DC power supply 4 of the embodiment shown in FIG.
Is the comparison output signal V of the comparator 25_PWith the band-pass type
Output signal V of the filter circuit 24_BAmplified signal V_ASubtraction circuit
27, the comparison output signal V of the comparator 25_PIncluded in
Signal transmission in the control system
Input current I generated by the delay of_ACAnd AC input
Voltage V_ACOscillation phenomenon can be prevented, and high-frequency
Style I_NAnd high frequency voltage V_NDoes not occur. Because of this,
There is no need for a damper circuit that generates loss, and AC-DC
High frequency generated on AC input side without lowering conversion efficiency
Wave current I_NAnd high frequency voltage V_NOf DC power supply 4 due to
Operation can be prevented. Further, the input current detector 19
Input current I_ACIs the current I_ACVoltage of the level corresponding to
And the output signal V of the multiplication circuit 23_MAnd input current
Detection signal V of detector 19_TwoIs compared with the comparator 25
And the comparison output signal V of the comparator 25_PAnd bandpass fill
Output signal V of the_BAmplified signal V_AAnd subtract the difference times
The difference signal V of the subtraction circuit 27_DFAccording to
The PWM modulation signal V by the PWM comparator 29 _PWM
And the PWM output from the PWM comparator 29
M modulated signal V_PWMIs the first or second on / off control signal
V_G1, V_G2AC input voltage V_ACEvery half cycle of the first
Is applied to the gate terminals of the second MOS-FETs 11 and 12.
To turn on the first or second MOS-FET 11, 12.
By performing the off control, the AC input current I_ACThe AC input
Voltage V_ACAnd the input power factor is increased to approximately 1.0.
Can be raised.

The embodiment of the present invention is limited to the above-described embodiment.
It is not specified and various changes are possible. For example,
In the embodiment, the band-pass filter circuit 24 detects the input current.
Output 19 and the AC input current I_AC1-2 contained in
High frequency current I in the frequency band of kHz_NThe bandpass fill
Form extracted by the data circuit 24 and input to the subtraction circuit 27
, But as shown by the broken line in FIG.
The filter circuit 24 is connected to the secondary of the input voltage detecting transformer 18.
Connected to the winding, AC input voltage V_AC1-2KH contained in
High frequency voltage V in frequency band z_NThe bandpass filter times
It may be extracted by the path 24 and input to the subtraction circuit 27.
In the above embodiment, the switching circuit 15 is configured.
Has a parasitic diode as a switching element
MOS-FET (MOS field effect transistor)
Although the form used was shown, it was added in parallel with the switching element.
If an external diode is used, a bipolar transistor, J
-FET (junction field effect transistor) or IGBT
(Insulated gate transistor) and the like can also be used. Change
Meanwhile, in the above embodiment, the exchange from the single-phase AC generator 3 is performed.
Input voltage V_ACIs the DC output voltage V_DCDC power to convert to
The embodiment in which the present invention is applied to the device 4 has been described.
The line voltage from the multi-phase AC power supply having the above phases
The present invention is also applied to a DC power supply that converts to an output voltage.
It is possible. Fig. 3 shows a three-phase AC power supply
DC power supply devices 4A, 4B,
4C and each DC power supply 4A, 4B, 4C
Of the DC-DC converter 20 are connected in parallel.
DC output voltage V to load 5 via_OSupply DC power
It shows the device. In FIG. 3, 18A, 18
B and 18C are for detecting phase voltage of U phase, V phase and W phase respectively
Transformers, 19A, 19B, and 19C are U-phase and V-phase, respectively.
3 shows a phase and W-phase line current detector. In addition, between U-V phase, V
-Each DC power supply 4 connected between the W phase and between the W and U phases
The internal configuration of A, 4B, and 4C is the DC power supply 4 shown in FIG.
Therefore, detailed illustration is omitted. Also figure
In the DC power supply device shown in FIG.
Each phase voltage V _U, V_V, V_WAnd DC power supply 4A between each line,
4B, 4C, the first and second MOS-FETs 11A-
Gate ends of 12A, 11B-12B, 11C-12C
1st-2nd, 3rd-4th, 5th-6th
ON / OFF control signal V_G1-V _G2, V_G3-V_G4, V_G5-V
_G6Are as shown in FIGS. 4A to 4G.

[0015]

According to the present invention, high-frequency current and high-frequency voltage generated on the AC input side can be prevented without using a damper circuit that generates power loss. Malfunction of the power supply device can be prevented. In addition, since malfunction of the DC power supply can be prevented only by changing the circuit configuration in the control circuit,
There is no need to provide a large and large-capacity damper circuit on the AC input side, and there is an advantage that the DC power supply can be downsized.

[Brief description of the drawings]

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

FIG. 2 is a time chart of an AC input voltage and each on / off control signal of the DC power supply device shown in FIG.

FIG. 3 is an electric circuit diagram showing another embodiment of the DC power supply device according to the present invention.

4 is a time chart of each phase voltage and each on / off control signal of the DC power supply device shown in FIG.

FIG. 5 is an electric circuit diagram showing a DC power supply system using a conventional DC power supply device.

FIG. 6 is a waveform diagram showing a high-frequency voltage and a high-frequency current generated on the input side of the DC power supply device of FIG.

FIG. 7 is an electric circuit diagram showing an example of a conventional high-frequency countermeasure;

[Explanation of symbols]

1. . . Power source, 2. . . Fittings, 3. . . 3. AC generator (AC power supply); . . 4. DC power supply unit; . . load,
6. . . Control means, 7. . . Capacitor, 8. . . Resistance, 9. . . 10. damper circuit; . . Reactor, 1
1. . . A first MOS-FET (switching element),
11a. . . 11. a first parasitic diode; . . Second MOS-FET (switching element), 12a. . . Second
13. parasitic diode of . . First diode, 1
4. . . Second diode, 15. . . Switching circuit; 16. . . 17. smoothing capacitor; . . Control circuit,
18. . . Transformer for input voltage detection, 19. . . 20. an input current detector (input current detection means); . . DC-DC
Converter, 21. . . Reference power supply, 22. . . 23. an error amplifier (output voltage detecting means); . . 24. multiplication circuit (multiplication means); . . 24. band-pass filter circuit (filter circuit); . . 26. comparator (comparing means); . . Amplifier, 27. . . 28. subtraction circuit (subtraction means); . . Triangular wave oscillation circuit, 29. . . PWM comparator, 3
0. . . 30. positive / negative determination circuit; . . Inverter, 32. . .
First NAND gate, 33. . . Second NAND gate, 34. . . Three-phase AC generator (multi-phase AC power supply)

Continued on the front page F term (reference) 5G065 AA01 AA05 AA06 AA08 BA00 DA06 DA07 HA04 HA13 JA01 KA02 KA05 LA01 LA02 MA01 MA03 MA09 MA10 5H006 AA02 AA05 CA02 CA07 CB02 CC02 DB02 DC02 DC05 FA01 FA02 5H740 AA03 BB05 BB05 BB05 BB05 BB05

Claims (3)

[Claims] 1. An AC power supply from an AC power supply having at least one switching element and controlling the switching elements to be turned on / off according to an output voltage and an input voltage and an input current supplied from an AC power supply. In a DC power supply that converts the input current to the input voltage supplied from the AC power source while converting the input voltage into a constant voltage DC power, an output voltage that detects a difference between the level of the output voltage and a constant voltage level Detecting means, a multiplying means for outputting a product signal of the input voltage and a detection signal of the output voltage detecting means, a filter circuit for extracting a high-frequency component contained in the input current or the input voltage, and Subtraction means for outputting a difference signal between an output signal and an output signal of the filter circuit, wherein the switch is provided in accordance with an output signal of the subtraction means. DC power supply device, characterized in that the on-off control of the ring element. 2. An input current detection means for detecting a level of the input current, a comparison means for comparing an output signal of the multiplication means and a detection signal of the input current detection means, and a comparison output signal of the comparison means. Subtraction means for outputting a difference signal from the output signal of the filter circuit; and on-off means for applying to the control terminal of the switching element according to the output signal of the subtraction means.
2. The DC power supply according to claim 1, further comprising control signal forming means for forming an off control signal, wherein on / off control of the switching element is performed by an output signal of the control signal forming means. 3. A DC power supply device, wherein the DC power supply device according to claim 1 or 2 is connected for each line of a polyphase AC power supply having three or more phases.