JPH10127048A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an input power factor and eliminate a waveform distortion by achieving an unneeded amount of resistance for an element without adding a complex additional circuit and another switching element in a power supply device with a switching means for adjusting power to be fed to a load. SOLUTION: An AC power supply PS is rectified by a rectification circuit Rec1, a DC power supply obtained by smoothing with a smoothing capacity C0 is switched by a switching element S1, an energy is accumulated in an inductor Ls, and the energy of the inductor Ls is discharged to a smoothing capacitor C0 via a diode D1 and at the same time is transferred to a load and a capacitor C1 via a current-limiting element Z1 and a rectification element Rec2. In this case, a capacitor Cs and a diode D0 are added and a period where current flows from the AC power supply PS is increased, thus improving an input power factor and eliminating a waveform distortion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter for controlling power transmitted to a load by a switching element.

[0002]

2. Description of the Related Art FIG. 24 shows a power supply device using a rectifying / smoothing circuit of a capacitor input type. In this device, the AC power supply P
Since the input current flows only near the peak of the voltage of S, it has a low power factor, contains many harmonics, and adversely affects other devices. Therefore, one of means for improving the power factor and suppressing harmonics is shown in FIG. This device is disclosed in Japanese Patent Application
The AC power supply PS is rectified by a rectifier circuit Rec1 and is smoothed by an inductor L0 and a capacitor C0 to produce a DC power supply. This is input to the inverter circuit INV, and the AC output is supplied to a load (in this case, a discharge lamp). This inverter circuit INV
, The capacitor C1 is charged by the feedback current. Turning on the switching element S0 applies the voltage of the capacitor C1 to the inductor L0. When the switching element S0 is turned off, the energy stored in the inductor L0 charges the capacitor C0 via the AC power supply PS and the rectifier circuit Rec1. As described above, even when the voltage V _PS of the AC power supply PS is lower than the voltage of the capacitor C0, the induced voltage of the inductor L0 is superimposed on the full-wave rectified waveform of the AC power supply, so that the period during which the input current flows becomes longer,
Power factor and waveform distortion are improved.

FIG. 26 shows a second conventional example. This device is proposed in Japanese Patent Application Laid-Open No. 4-87567. When the switching element Q1 is turned on, the capacitor C0 and the inductor L
s, a current flows through the path of the switching element Q1. When the switching element Q1 is turned off, the energy of the inductor Ls is stored in the capacitor Cs via the diode D0. At this time, the voltage of the capacitor Cs has the polarity of the arrow. The switching element Q1 is turned on again, a current starts to flow through the path of the capacitor C0, the inductor Ls, and the switching element Q1, and the voltage obtained by full-wave rectifying the AC power supply PS and the voltage of the capacitor Cs are superimposed.
The rectifier circuit Rec1 turns on, and a current flows through the path of the capacitor Cs, the switching element Q1, the rectifier circuit Rec1, and the AC power supply PS to the AC power supply PS via the switching element Q1. As described above, since the period during which the current flows to the AC power supply PS becomes longer, the power factor and the waveform distortion can be improved.

[0004]

In the above-mentioned prior art 1 shown in FIG. 25, the switching element S0 is required to improve the power factor and the efficiency, which causes an increase in cost. Further, in the conventional example 2 shown in FIG.
1 turns on, and when the electric charge stored in the capacitor Cs flows to the AC power supply PS via the rectifier circuit Rec1, a very large current flows because there is no current limiting element.
The switching element Q1 having a large withstand element is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply device having a switching means for adjusting power to be sent to a load, a complicated additional circuit, an additional An object of the present invention is to improve the input power factor and the waveform distortion without adding a switching element and without giving the element an unnecessary resistance.

[0006]

According to the present invention, in order to solve the above-mentioned problems, as shown in FIG.
S and a rectifier circuit Rec1 for rectifying the AC power supply PS.
A smoothing capacitor C0 for smoothing the output of the rectifier circuit Rec1, an impedance circuit including a rectifying element Rec2 and a current limiting element Z1 for supplying power from the smoothing capacitor C0 to the load, and an impedance circuit using the smoothing capacitor C0 as a DC voltage source. And a switching element S1 that performs a switching operation for adjusting the power transmitted to the load via the switching element S1. One end of the switching element S1 is connected to one end of the smoothing capacitor C0, and the other end of the switching element S1 is connected to the other end. An inductor Ls is connected between the other end of the capacitor C0 and a load is connected in parallel with the inductor Ls via the impedance circuit, and a rectifier circuit Rec1 for rectifying the AC power supply PS. One rectification output terminal is connected to a smoothing capacitor C via a diode D0. The polarity of the diode D0 is oriented so that the smoothing capacitor C0 can be charged from the rectifier circuit Rec1, and the diode D0 and the rectifier output terminal of the rectifier circuit Rec1 are connected to each other. Is connected to the other end of the switching element S1 via a power factor improving capacitor Cs.
A rectifying element D1 is provided at both ends of the switching element S1 in anti-parallel, and the polarity of the rectifying element D1 is
Characterized in that the current does not flow out of the device.

The embodiment of FIG. 6 includes an AC power supply PS, a rectifier circuit Rec1 for rectifying the AC power supply PS, and a smoothing capacitor C0 for smoothing the output of the rectifier circuit Rec1, and the smoothing capacitor C0 is connected to a DC voltage source. And the smoothing capacitor C0, the switching element S1, and the inductor Ls
To form a first closed circuit, and the switching element S
When 1 is on, energy is stored in the inductor Ls. When the switching element S1 is off, the load and the inductor Ls are included in a polarity such that the energy stored in the inductor Ls is transmitted to the load side. In a step-up / step-down power converter in which a rectifying element D2 is connected in the second closed circuit and the output voltage can be adjusted from the input voltage or lower to the input voltage or higher, one of the rectifier circuits Rec1 for rectifying the AC power supply PS. The rectification output terminal is connected to the connection point between the smoothing capacitor C0 and the inductor Ls via the diode D0, and the polarity of the diode D0 is such that the rectification circuit Rec1 can charge the smoothing capacitor C0. The connection point between the diode D0 and the rectification output terminal of the rectifier circuit Rec1 is connected via a power factor improving capacitor Cs. It is connected to a connection point of the switching element S1 and the inductor Ls, the switching element S1
Rectifier elements D1 are provided in anti-parallel at both ends of the rectifier element D1.
The polarity of 1 is a direction in which the current from the smoothing capacitor C0 does not flow out. When the switching element S1 is off, the energy stored in the inductor Ls is transmitted to the load side in the second closed circuit. The current limiting element L1 is connected.

The embodiment of FIG. 17 includes an AC power supply PS, a rectifier circuit Rec1 for rectifying the AC power supply PS, and a smoothing capacitor C0 for smoothing the output of the rectifier circuit Rec1, and the smoothing capacitor C0 is used as a DC voltage source. A first closed circuit is formed by the switching element S1, the load, and the first inductor L1 provided immediately before the load. When the switching element S1 is on, energy is transmitted to the load and the first inductor L1 And a second closed circuit is formed for the first inductor L1 and the load so that the energy stored in the first inductor L1 continues to flow to the load side when the switching element S1 is off. In the step-down type power conversion device, the output voltage can be adjusted within the range of the input voltage or less by connecting the freewheeling diode Df so that A second inductor Ls is connected so as to form a second closed circuit together with the smoothing capacitor C0 and the switching element S1, and has a polarity such that no current flows from the load side into the switching element S1 or the second inductor Ls. A rectifying element D2 is connected in the path from the first inductor L1 to the load, and one rectifying output terminal of the rectifying circuit Rec1 for rectifying the AC power PS is connected to the smoothing capacitor C0 via the diode D0. And the polarity of this diode D0 is such that the rectifier circuit Rec1 can charge the smoothing capacitor C0.
A connection point between the diode D0 and the rectification output terminal of the rectifier circuit Rec1 is connected to a connection point between the switching element S1 and the second inductor Ls via a power factor improving capacitor Cs. The rectifier D1 is provided in anti-parallel, and the polarity of the rectifier D1 is such that the current from the smoothing capacitor C0 does not flow out.

The embodiment of FIG. 21 includes an AC power supply PS, a rectifier circuit Rec1 for rectifying the AC power supply PS, and a smoothing capacitor C0 for smoothing the output of the rectifier circuit Rec1, and using the smoothing capacitor C0 as a DC voltage source. , Form a first closed circuit with the inductor Ls, the rectifying element D2 and the load, store energy in the inductor Ls when the switching element S1 is turned on, and store energy in the inductor Ls when the switching element S1 is turned off. Rectifies the AC power supply PS in a step-up power converter in which the output voltage can be adjusted to a voltage equal to or higher than the input voltage by sending a voltage obtained by superimposing the induced electromotive voltage caused by the above and the voltage of the smoothing capacitor C0 to the load side. One rectification output terminal of the rectification circuit Rec1 is connected to the smoothing capacitor C0 and the inductor via the diode D0. Is connected to the connection point of data Ls,
The polarity of the diode D0 is such that the smoothing capacitor C0 can be charged from the rectifier circuit Rec1, and the connection point between the diode D0 and the rectifier output terminal of the rectifier circuit Rec1 is a power factor improving capacitor. The switching element S1 is connected to the connection point of the inductor Ls via Cs, and a rectifying element D1 is provided in both ends of the switching element S1 in anti-parallel. The polarity of the rectifying element D1 is such that the current from the smoothing capacitor C0 flows. It is a direction that does not come out, the smoothing capacitor C0, the inductor Ls, and the rectifying element D
The second current limiting element L1 is connected immediately before the load in the first closed circuit including the load 2 and the load, and the energy of the current limiting element L1 is returned to the load even when the rectifying element D2 is off. Return diode Df for forming a closed circuit
Is connected.

In any case, a power factor improving circuit including the power factor improving capacitor Cs, the inductor Ls and the diode D0 is added to at least one of the positive and negative terminals of the smoothing capacitor C0. Good. Regarding the circuit constants and the switching conditions, immediately after the switching element S1 is turned off, after the charging current flowing into the power factor improving capacitor Cs ends, the power factor improving capacitor Cs
, The current continues to flow until the voltage polarity of the power factor improving capacitor Cs is inverted, and the power factor improving capacitor Cs
The inverted voltage of s is preferably set to be equal to or higher than the rectified voltage of the AC power supply PS. Then, it is preferable to have a function of turning on the switching element S1 when the inversion voltage of the power factor improving capacitor Cs increases and the voltage across the switching element S1 decreases to a predetermined voltage (substantially zero voltage). . The output voltage to the load may be DC, or an inverter circuit may be connected immediately before the load, and the output voltage to the load may be AC output (FIGS. 9 and 1).
9). Further, the rectifying element may be replaced with a capacitor C2, and the output voltage to the load may be a high-frequency output (FIG. 1).
6, FIG. 23). Further, a transformer T1 may be used instead of the inductor Ls (FIGS. 11 to 14). In the transformer T1, when the switching element S1 is turned on, even if a current flows in the primary winding, no current flows in the secondary winding, and energy is stored in the transformer T1. When turned off, a current may flow through the secondary winding to perform a flyback operation such that power is supplied to the load (FIG. 11), or when the switching element S1 is turned on. When a current flows through the primary winding, a current also flows through the secondary winding and power is supplied to the load.
A device that performs a forward operation such that no current flows in both the secondary windings (FIG. 14) may be used.

[0011]

FIG. 1 shows a basic principle diagram of the present invention. The AC power supply PS is rectified by the rectifier circuit Rec1, and is smoothed by the capacitor C0 via the diode D0. Power is supplied to the load through the impedance circuit Z1 and the rectifier circuit Rec2 by performing the switching operation of the switching element S1 using the capacitor C0 as a DC voltage source. The capacitor C1 is a load voltage smoothing capacitor, and F1 is a high frequency cut filter.

2 to 5 show the operation. When the switching element S1 is turned on, the capacitor C
0, a current flows through the switching element S1 and the inductor Ls. When the switching element S1 is turned off, the energy of the inductor Ls is released through the path of FIG. That is, the inductor Ls, the diode D0, and the capacitor Cs
A current flows through the path, and the capacitor Cs is charged.
In the circuit after the rectifier circuit Rec2 including the load, a current flows through at least one of the paths when the switching element S1 is on or off.

Then, after all the energy of the inductor Ls is released to the circuit after the capacitor Cs and the rectifier circuit Rec2, the path of the capacitor Cs, the rectifier circuit Rec1, the AC power supply PS, the capacitor C0, and the inductor Ls (the path of FIG. 4) ), A current flows, and the charge of the capacitor Cs is charged in the capacitor C0.

The charging voltage of the capacitor Cs becomes zero,
Subsequently, the capacitor Cs is charged with a voltage of opposite polarity, and when the voltage becomes equal to the rectified voltage of the AC power supply PS, the voltage across the switching element S1 becomes zero, so that the diode D1 turns on and the inductor Ls , A diode D1 and a capacitor C0 (a path shown in FIG. 5). At this time, if the switching element S1 is turned on, zero voltage switching can be performed when the switching element S1 is turned on.

When the switching element S1 is turned off, the charging voltage of the capacitor Cs is higher than the charging voltage of the capacitor C0. Thereafter, a current flows through the path shown in FIG. 4, and the charge of the capacitor Cs is charged in the capacitor C0. At this time, the charging current continues to flow until the voltage of the capacitor Cs is inverted, and each constant has a predetermined value so that the inverted voltage reaches or exceeds the rectified voltage of the AC power supply PS.

As described above, by switching the switching element S1, the current can be forced to flow to the AC power supply PS, thereby extending the period during which the current flows from the AC power supply PS, thereby increasing the power factor / waveform. Is to improve. Also, as shown in FIG. 1, the AC power supply PS and the rectifier circuit Re.
A filter F1 may be provided between the switching element c1 and the switching frequency component of the switching element S1 higher than the frequency of the AC power supply PS. Further, as described above, zero voltage switching is performed when the current flows in the path shown in FIG. 5, so that there is no possibility that an excessive current flows when the switching element is turned on as in the second conventional example. .

[0017]

FIG. 6 shows a first embodiment of the present invention. AC power supply P
S is full-wave rectified by a diode bridge circuit Rec1 including diodes Da to Dd, and is smoothed by a capacitor C0 via a diode D0. Switching element S1
Is turned on, the capacitor C0 and the switching element S
1. A current flows through the path of the inductor Ls and the inductor L
Energy is stored in s. When the switching element S1 is turned off, part of the energy of the inductor Ls is charged in the capacitor Cs through a path including the inductor Ls, the diode D0, and the capacitor Cs. The remaining energy is inductor Ls, load / capacitor C1, inductor L
1. It is sent to the load through the path of the diode D2. The inductor L1 limits the current on the load side so that when the switching element S1 is turned off, the energy stored in the inductor Ls is not concentrated only on the load side, but is also charged on the capacitor Cs. Then, after all the energy of the inductor Ls is released, the capacitor Cs, the diode Dd (or Db), the AC power supply PS, and the diode Da
(Or Dc), a current flows through the path of the capacitor C0 and the inductor Ls, and the charge of the capacitor Cs is charged in the capacitor C0. Since all the charge of the capacitor Cs is discharged, the capacitor Cs is charged with a voltage of the opposite polarity, and when the voltage becomes equal to the rectified voltage of the AC power supply PS, the voltage across the switching element S1 becomes zero. , The diode D1 is turned on, and a current flows through the path of the inductor Ls, the diode D1, and the capacitor C0.
At this time, by turning on the switching element S1, on-time zero voltage switching becomes possible.

When the switching element S1 is turned off, the charging voltage of the capacitor Cs is higher than the charging voltage of the capacitor C0. Thereafter, when the charge of the capacitor Cs is charged to the capacitor C0, the charging current is the voltage of the capacitor Cs. Each constant has a predetermined value so that the inverted voltage reaches the rectified voltage of the AC power supply PS or more.

The power to the load is adjusted by the switching element S1.
It can be adjusted by the switching frequency and the on duty. That is, the switching element S1, the inductor Ls, the diode D2, the capacitor C1, and the circuit portion configured by the load constitute a kind of step-up / step-down chopper, so that the load voltage can be adjusted in a range from zero to the input voltage or more.

The state of the switching element S1, the current I _S1 of the switching element S1, the current I Cs of the capacitor _Cs ,
Current Iin of rectifier circuit Rec1 and inductor L
FIG. 7 shows the current I _L1 flowing through No. 1. AC power supply PS
Voltage V _PS, current Ia is input to the rectifier circuit Rec1 of
c, the current I _PS input to the filter F1 is shown in FIG.
As described above, by switching the switching element S1, the current can be forced to flow to the AC power supply PS, and the period during which the current flows to the AC power supply PS can be lengthened to improve the power factor and the waveform. .

FIG. 9 shows an embodiment in which a discharge lamp load is used as a load. In order to apply an alternating current to the discharge lamp, a full-bridge inverter circuit including switching elements Sa to Sd and diodes D3a to D3d is provided. It is connected to the subsequent stage of the smoothing capacitor C1. A value calculated by the output command value calculator based on each detected value of the lamp voltage and the lamp current is input to the comparator, and is compared with a signal from the triangular wave high-frequency oscillator to generate a PWM control signal. ON duty is controlled. FIG.
The position of the rectifier diode D2 and the inductor L1 may be changed as in 0.

Next, FIG. 11 shows a second embodiment of the present invention.
In the present embodiment, the inductor Ls in FIG. 6 is replaced with a transformer T1. The transformer T1 will be described. When the switching element S1 is turned on, the transformer T1 is turned on.
1 even if a current flows through the primary winding N1 of the secondary winding N2.
, No current flows, and energy is stored in the transformer T1. When the switching element S1 is turned off, a current flows through the secondary winding N2 of the transformer T1, and power is supplied to the load. The transformer performs the flyback operation as described above.

The operation of the circuit is basically the same as that of the first embodiment.
When the switching element S1 is turned on, a current flows through the path of the capacitor C0, the switching element S1, and the primary winding N1 of the transformer T1, and energy is stored in the transformer T1. When the switching element S1 is turned off, part of the energy of the transformer T1 is transferred to the transformer T1.
1, primary winding N1, diode D0, capacitor Cs
Is charged in the capacitor Cs along the path. The remaining energy is transferred from the secondary winding N2 of the transformer T1, the diode D2,
It is sent to the load through the path of the inductor L1 and the load / capacitor C1. After all the energy of the transformer T1 is released, the capacitor Cs, the diode Dd (or Db),
The capacitor Cs is charged with the electric charge of the capacitor Cs through the path of the AC power supply PS, the diode Da (or Dc), the capacitor C0, and the primary winding N1 of the transformer T1. All the charges of the capacitor Cs are discharged, and then the capacitor Cs is charged with a voltage of the opposite polarity. When the voltage becomes equal to the rectified voltage of the AC power supply PS, the voltage across the switching element S1 becomes zero. So the diode D
1 is turned on, and a current flows through the path of the primary winding N1, the diode D1, and the capacitor C0 of the transformer T1. At this time, turning on the switching element S1 enables zero voltage switching. By switching the switching element S1 in this manner, the AC power supply P
S, a current can be supplied to the AC power supply P
The power factor and the waveform can be improved by extending the period in which the current flows through S.

Also in this embodiment, when the switching element S1 is turned off, the inductor L1 does not concentrate the energy stored in the transformer T1 only on the secondary side, that is, the load side, but also charges the capacitor Cs. This limits the current on the load side.

The circuit shown in FIG. 12 is obtained by omitting the inductor L1 connected to the secondary side of the transformer T1 in FIG. The operation is basically the same as that of the circuit shown in FIG. 11, except that the energy stored in the transformer T1 when the switching element S1 is turned on is changed by the switching element S1.
1 is turned off and sent to the secondary side of the transformer T1.
The energy stored in the primary-side leakage reactance is charged in the capacitor Cs.

The circuit shown in FIG. 13 is such that the inductor L1 shown in FIG. 6 is constituted by an autotransformer T1. The operation is basically the same as the circuit of FIG.

Next, FIG. 14 shows a third embodiment of the present invention.
In the present embodiment, the inductor Ls in FIG. 6 is replaced with a transformer T1. The transformer T1 will be described. When the switching element S1 is turned on, the transformer T1 is turned on.
1, when a current flows through the primary winding N1 of the secondary winding N2.
Current also flows to supply power to the load. When the switching element S1 is turned off, no current flows through the primary winding N1 and the secondary winding N2 of the transformer T1. The transformer performs the forward operation as described above.

The operation is basically very similar to that of the second embodiment, but when the switching element S1 is turned on, the transformer T
It is characterized in that energy is sent to the secondary side of the capacitor 1 and that the capacitor Cs is charged with the excitation energy of the transformer T1 when the switching element S1 is turned off. FIG.
3 may be changed to a single-winding transformer.

Next, FIG. 15 shows a fourth embodiment of the present invention.
The circuit of FIG. 15 has the same configuration as that of the first embodiment shown in FIG. 6 except that the inductor Ls, the capacitor Cs, and the diode D
0, the position of the power factor improving circuit composed of the switching element S1 is changed from the positive side to the negative side of the capacitor C0.

The operation is basically very similar to that of the first embodiment.
When the switching element S1 is turned on, the capacitors C0,
A current flows through the path of the inductor Ls and the switching element S1, and energy is stored in the inductor Ls. When the switching element S1 is turned off, a part of the energy of the inductor Ls is charged in the capacitor Cs through the path of the inductor Ls, the capacitor Cs, and the diode D0. The remaining energy is sent to the load side. Then, after all the energy of the inductor Ls is released, the capacitor C
s, inductor Ls, capacitor C0, diode Dd
(Or Db), a current flows through the path of the AC power supply PS and the diode Da (or Dc), and the charge of the capacitor Cs is charged in the capacitor C0. All the charges of the capacitor Cs are discharged, and then the capacitor Cs is charged with a voltage of the opposite polarity. When the voltage becomes equal to the rectified voltage of the AC power supply PS, the voltage across the switching element S1 becomes zero. Therefore, the diode D1 turns on, and a current flows through the path of the inductor Ls, the capacitor C0, and the diode D1. At this time, turning on the switching element S1 enables zero voltage switching.

Next, FIG. 16 shows a fifth embodiment of the present invention.
The circuit of FIG. 16 is obtained by replacing the diode D2 on the load side with a capacitor C2 in the configuration of the first embodiment shown in FIG. The capacitor C2 blocks a DC component and applies a high frequency equal to a switching frequency to a load.

FIG. 17 shows a sixth embodiment of the present invention. The AC power supply PS is full-wave rectified by a diode bridge circuit Rec1 including diodes Da to Dd, and is smoothed by a capacitor C0 via a diode D0. Switching element S
1 turns on, the capacitor C0 and the switching element S
1. A current flows through the path of the inductor Ls and the inductor L
Energy is stored in s. Also, a diode D2,
At the same time that power is transmitted to the load side via the inductor L1, energy is also stored in the inductor L1. When the switching element S1 is turned off, the energy stored in the inductor Ls is changed to the inductor Ls and the diode Ds.
0, the capacitor Cs is charged through the path of the capacitor Cs. The energy stored in the inductor L1 is equal to the inductor L1, the load / capacitor C1, and the diode Df.
Route to the load. Thereafter, after all the energy of the inductor Ls is released to the capacitor Cs, the capacitor Cs, the diode Dd (or Db), and the AC power supply P
S, diode Da (or Dc), capacitor C0,
A current flows through the path of the inductor Ls, and the charge of the capacitor Cs is charged in the capacitor C0. Since all the charge of the capacitor Cs is discharged, the capacitor Cs is charged with a voltage of the opposite polarity, and when the voltage becomes equal to the rectified voltage of the AC power supply PS, the voltage across the switching element S1 becomes zero. , The diode D1 is turned on, and a current flows through the path of the inductor Ls, the diode D1, and the capacitor C0. At this time, by turning on the switching element S1, on-time zero voltage switching becomes possible.

When the switching element S1 is turned off, the charging voltage of the capacitor Cs is higher than the charging voltage of the capacitor C0. Thereafter, when the charge of the capacitor Cs is charged to the capacitor C0 as described above, the charging current becomes It continues to flow until the voltage polarity of the capacitor Cs is inverted,
Each constant has a predetermined value so that the inverted voltage reaches the rectified voltage of the AC power supply PS or more.

The power adjustment to the load is performed by the switching element S1.
Can be adjusted by the switching frequency and the on-duty. That is, the switching element S1 and the inductor L
1, a circuit portion composed of the diode Df, the capacitor C1, and the load constitutes a kind of step-down chopper, so that the load voltage can be adjusted within a range from zero to the input voltage.

The state of the switching element S1 of this embodiment, the current I _S1 of the switching element _S1 , the capacitor Cs
FIG. 18 shows the current I _Cs and the current Iin of the rectifier circuit Rec1. The power supply voltage V _PS of the AC power supply PS, the rectifier circuit R
Current is inputted to ec1 Iac, the current I _PS to be inputted to the filter circuit F1 shown in FIG. As described above, by switching the switching element S1, it is possible to force the current to flow to the AC power supply PS, thereby increasing the period during which the current flows to the AC power supply PS and improving the power factor and waveform. Can be.

FIG. 19 shows an embodiment in which a discharge lamp load is used as a load. In order to apply an alternating current to the discharge lamp, switching elements Sa to Sd and diodes D3a to D3d are used.
Is connected to the subsequent stage of the smoothing capacitor C1.

FIG. 20 shows a seventh embodiment of the present invention. FIG.
17 changes the position of the power factor improving circuit including the inductor Ls, the capacitor Cs, the diode D0, and the switching element S1 from the positive side of the capacitor C0 to the negative side in the configuration of the sixth embodiment shown in FIG. It was done.
The operation is basically very similar to that of the sixth embodiment, but when the switching element S1 is turned on, a current flows through the path of the capacitor C0, the inductor Ls, and the switching element S1, and energy is accumulated in the inductor Ls. At the same time, power is sent to the load side, and energy is stored in the inductor L1. When the switching element S1 is turned off, the inductor L
energy of the inductor Ls, the capacitor Cs,
The capacitor Cs is charged through the path of the diode D0.
The energy of the inductor L1 is equal to the inductor L1,
It is sent to the load through the path of the capacitor C1 / load and the diode Df. Thereafter, after all the energy of the inductor Ls is released, the charge of the capacitor Cs is transferred to the capacitor C0 through the path of the capacitor Cs, the inductor Ls, the capacitor C0, the diode Dd (or Db), the AC power supply PS, and the diode Da (or Dc). Charged. All charges of the capacitor C0 are discharged, and then the capacitor Cs
Are charged with voltages of opposite polarities, and when the voltage becomes equal to the rectified voltage of the AC power supply PS, the voltage across the switching element S1 becomes zero, so that the diode D1 turns on, the inductor Ls and the capacitor C0. , A current flows through the path of the diode D1. At this time, turning on the switching element S1 enables zero-voltage switching.

FIG. 21 shows an eighth embodiment of the present invention. The AC power supply PS includes a rectifier circuit Re including diodes Da to Dd.
It is full-wave rectified by c1 and smoothed by a capacitor C0 via a diode D0. When the switching element S1 is turned on, a current flows through the path of the capacitor C0, the inductor Ls, and the switching element S1, and energy is accumulated in the inductor Ls. When the switching element S1 is turned off,
Part of the energy stored in the inductor Ls is charged in the capacitor Cs through the path of the inductor Ls, the capacitor Cs, and the diode D0. The remaining energy is obtained by superimposing the induced electromotive voltage of the inductor Ls and the voltage of the capacitor C0 on the inductor Ls, the diode D2,
Inductor L1, load / capacitor C1, capacitor C
0 to the load. Then, after all the energy of the inductor Ls is released, the capacitor C
s, inductor Ls, capacitor C0, diode Dd
(Or Db), the path of the AC power supply PS and the diode Da (or Dc), the charge of the capacitor Cs is
It is charged to zero. All the charges of the capacitor Cs are discharged, and then the capacitor Cs is charged with a voltage of the opposite polarity. When the voltage becomes equal to the rectified voltage of the AC power supply PS, the voltage across the switching element S1 becomes zero. Therefore, the diode D1 turns on, and the inductor Ls,
A current flows through the path of the capacitor C0 and the diode D1. At this time, turning on the switching element S1 enables zero voltage switching.

When the switching element S1 is turned off, the charging voltage of the capacitor Cs is higher than the charging voltage of the capacitor C0. Thereafter, when the charge of the capacitor Cs is charged to the capacitor C0, the charging current is the voltage of the capacitor Cs. Each constant has a predetermined value so that the inverted voltage reaches the rectified voltage of the AC power supply PS or more.

The power supplied to the load is determined by the switching element S
It can be adjusted by the switching frequency and the on-duty of 1. Since a circuit portion composed of the switching element S1, the inductor L1, the diode Df, the capacitor C1, and the load constitutes a kind of boost chopper, the load voltage can be adjusted at a voltage higher than the input voltage.

The state of the switching element S1, the current I _S1 of the switching element _S1 , the capacitor Cs
FIG. 18 shows the current I _Cs and the current Iin of the rectifier circuit Rec1. The power supply voltage V _PS of the AC power supply PS, the rectifier circuit R
Current is inputted to ec1 Iac, the current I _PS to be inputted to the filter circuit F1 shown in FIG. As described above, by switching the switching element S1, a current can be forcibly passed to the AC power supply PS.
The power factor and the waveform can be improved by extending the period during which the current flows to the AC power supply PS.

FIG. 22 shows a ninth embodiment of the present invention. FIG.
The circuit of FIG. 21 is obtained by changing the position of the power factor improving circuit including the inductor Ls, the capacitor Cs, and the diode D0 in the configuration of the eighth embodiment shown in FIG. The operation is basically very similar to that of the eighth embodiment, but when the switching element S1 is turned on, a current flows through the path of the capacitor C0, the switching element S1, and the inductor Ls, and energy is accumulated in the inductor Ls. When the switching element S1 is turned off, part of the energy stored in the inductor Ls is charged in the capacitor Cs through the path of the inductor Ls, the diode D0, and the capacitor Cs. The remaining energy is the inductor Ls in the form of a voltage obtained by superimposing the induced electromotive voltage of the inductor Ls and the voltage of the capacitor C0.
s, capacitor C0, diode D2, inductor L
1. It is sent to the load through the path of the load / capacitor C1. Then, after all the energy of the inductor Ls is released, the capacitor Cs and the diode Dd (or Dd
b), AC power supply PS, diode Da (or Dc),
In the path of the capacitor C0 and the inductor Ls, the capacitor C
The electric charge of s is charged in the capacitor C0. Capacitor C
s is discharged, and then the capacitor Cs is charged with a voltage of the opposite polarity, and the voltage is changed to the AC power supply PS.
Switching element S
1 becomes zero, the diode D1 turns on, the inductor Ls, the diode D1, and the capacitor C0.
The current flows through the path. At this time, the switching element S
Turning on 1 enables zero voltage switching.

FIG. 23 shows a tenth embodiment of the present invention. The circuit of FIG. 23 is obtained by replacing the diode D2 on the load side in the eighth embodiment shown in FIG. 21 with a capacitor C2. The capacitor C2 blocks a DC component and applies a high frequency equal to a switching frequency to a load.

[0044]

According to the present invention, in a power converter such as a chopper circuit composed of one switching element, a power factor improving circuit comprising a diode, an inductor and a capacitor is provided to provide a power factor and a waveform. Can be improved, and it is not necessary to increase the number of switching elements, and it can be realized at a relatively low cost. Further, since there is no sudden charge / discharge of the capacitor, the current withstand capability of the switching element does not need to be increased so much.

[Brief description of the drawings]

FIG. 1 is a circuit diagram for explaining a basic principle of the present invention.

FIG. 2 is a circuit diagram for explaining a first operation of the circuit of FIG. 1;

FIG. 3 is a circuit diagram for explaining a second operation of the circuit of FIG. 1;

FIG. 4 is a circuit diagram for explaining a third operation of the circuit of FIG. 1;

FIG. 5 is a circuit diagram for explaining a fourth operation of the circuit of FIG. 1;

FIG. 6 is a circuit diagram of a first embodiment of the present invention.

FIG. 7 is a waveform chart showing a high-frequency operation of the circuit of FIG. 6;

FIG. 8 is a waveform chart showing a low-frequency operation of the circuit of FIG. 6;

FIG. 9 is a circuit diagram showing an example in which the first embodiment of the present invention is applied to a discharge lamp lighting device.

FIG. 10 is a circuit diagram showing an example in which the arrangement of the load-side rectifying element and the current limiting element according to the first embodiment of the present invention is changed.

FIG. 11 is a circuit diagram according to a second embodiment of the present invention.

FIG. 12 is a circuit diagram illustrating an example in which a current limiting element on a load side according to a second embodiment of the present invention is omitted.

FIG. 13 is a circuit diagram showing an example in which the transformer according to the second embodiment of the present invention is changed to an autotransformer.

FIG. 14 is a circuit diagram according to a third embodiment of the present invention.

FIG. 15 is a circuit diagram according to a fourth embodiment of the present invention.

FIG. 16 is a circuit diagram according to a fifth embodiment of the present invention.

FIG. 17 is a circuit diagram of a sixth embodiment of the present invention.

FIG. 18 is a waveform chart showing a high-frequency operation of the circuit of FIG. 6;

FIG. 19 is a circuit diagram showing an example in which Embodiment 6 of the present invention is applied to a discharge lamp lighting device.

FIG. 20 is a circuit diagram of a seventh embodiment of the present invention.

FIG. 21 is a circuit diagram of an eighth embodiment of the present invention.

FIG. 22 is a circuit diagram of a ninth embodiment of the present invention.

FIG. 23 is a circuit diagram of a tenth embodiment of the present invention.

FIG. 24 is a circuit diagram of a conventional capacitor input type rectifying / smoothing circuit.

FIG. 25 is a circuit diagram of Conventional Example 1 in which the input power factor and the waveform distortion are improved.

FIG. 26 is a circuit diagram of a second conventional example in which the input power factor and the waveform distortion are improved.

[Explanation of symbols]

 PS AC power supply Rec1 Rectifier circuit D0 Diode D1 Diode C0 Smoothing capacitor Cs Power factor improving capacitor Ls Inductor S1 Switching element Z1 Current limiting element

Claims (5)

[Claims] An AC power supply, a rectifier circuit for rectifying the AC power supply, a smoothing capacitor for smoothing an output of the rectifier circuit, an impedance circuit including a rectifying element for supplying power from the smoothing capacitor to a load, and a current limiting element. A switching element that performs a switching operation for adjusting power transmitted to a load via an impedance circuit using a smoothing capacitor as a DC voltage source.
One end of the switching element is connected to one end of the smoothing capacitor, and an inductor is connected between the other end of the switching element and the other end of the smoothing capacitor. The inductor is connected in parallel with the inductor via the impedance circuit. Is connected, one rectification output terminal of the rectifier circuit for rectifying the AC power supply is connected to the other end of the smoothing capacitor via a diode, the polarity of the diode from the rectifier circuit to the smoothing capacitor. It is in a direction in which charging is possible, and a connection point between the diode and a rectification output terminal of the rectification circuit is connected to the other end of the switching element via a power factor improving capacitor, and Rectifiers are provided at both ends in anti-parallel, and the polarity of this rectifier is such that current does not flow from the smoothing capacitor. Electric power converter according to. 2. An AC power source, a rectifier circuit for rectifying the AC power source, and a smoothing capacitor for smoothing an output of the rectifier circuit. The smoothing capacitor is used as a DC voltage source. A closed circuit is formed to store energy in the inductor when the switching element is on and to transmit the energy stored in the inductor to the load side when the switching element is off, A rectifying element connected in a second closed circuit including a load and an inductor;
In a step-up / step-down power converter capable of adjusting an output voltage from an input voltage or lower to an input voltage or higher, one rectification output terminal of a rectifier circuit for rectifying the AC power is connected to a connection point between a smoothing capacitor and an inductor via a diode. The polarity of this diode is such that the smoothing capacitor can be charged from the rectifier circuit, and the connection point between the diode and the rectifier output terminal of the rectifier circuit is a power factor improving capacitor. Connected to the connection point between the switching element and the inductor via
A rectifying element is provided in both ends of the switching element in anti-parallel.The polarity of the rectifying element is such that current from the smoothing capacitor does not flow out, and when the switching element is off, energy stored in the inductor is transferred to the load side. A current limiting element is connected in a second closed circuit transmitted to the power converter. 3. An AC power supply, a rectifier circuit for rectifying the AC power supply, and a smoothing capacitor for smoothing an output of the rectifier circuit, wherein the smoothing capacitor is a DC voltage source, and is provided immediately before the switching element, the load, and the load. A first closed circuit is formed by the first inductor, and when the switching element is on, energy is transmitted to the load and energy is stored in the first inductor. A reflux diode is connected to the first inductor and the load so as to form a second closed circuit so that the energy stored in the first inductor continues to flow to the load side, and the output voltage is lower than the input voltage. In a step-down power converter that can be adjusted in a range, a second closed circuit is formed so as to form a second closed circuit together with the smoothing capacitor and the switching element. A rectifier element is connected in a path from the first inductor to the load with a polarity such that current does not flow from the load side to the switching element or the second inductor, and a rectifier for rectifying the AC power supply. One rectification output terminal of the circuit is connected via a diode to a connection point between the smoothing capacitor and the second inductor, and the polarity of the diode is such that the rectifying circuit can charge the smoothing capacitor. A connection point between the diode and a rectification output terminal of the rectification circuit is connected to a connection point between the switching element and the second inductor via a power factor improving capacitor;
A power converter wherein rectifying elements are provided in both ends of the switching element in anti-parallel, and the polarity of the rectifying element is such that current from the smoothing capacitor does not flow out. 4. An AC power supply, a rectifier circuit for rectifying the AC power supply, and a smoothing capacitor for smoothing an output of the rectifier circuit, wherein the smoothing capacitor is a DC voltage source, and a first capacitor is provided together with an inductor, a rectifying element and a load. A closed circuit is formed, when the switching element is turned on, energy is stored in the inductor, and when the switching element is turned off, a voltage obtained by superimposing the induced electromotive voltage due to the energy stored in the inductor and the voltage of the smoothing capacitor is applied to the load side. In a step-up power converter in which the output voltage can be adjusted at a voltage equal to or higher than the input voltage, one of the rectification output terminals of the rectification circuit for rectifying the AC power is connected to a smoothing capacitor and an inductor via a diode. Connected to the connection point, the polarity of this diode allows the smoothing capacitor to be charged from the rectifier circuit. That direction and are made, the connection point between the rectified output terminal of the diode and the rectifier circuit is connected to the connection point of the switching element and the inductor via a capacitor for power factor correction,
A rectifying element is provided in both ends of the switching element in anti-parallel, and the polarity of the rectifying element is such that the current from the smoothing capacitor does not flow out. A current limiting element is connected immediately before the load, and a circulating diode for forming a second closed circuit in which the energy of the current limiting element is returned to the load even when the rectifying element is in an off state. A power converter. 5. After the charging current flowing into the power factor improving capacitor immediately after the switching element is turned off, when the current flows from the power factor improving capacitor to the smoothing capacitor in a direction of charging the smoothing capacitor, the power factor improving. Circuit constants and switching conditions are set so that the current continues to flow until the voltage polarity of the capacitor for use reverses, and the reversal voltage of the capacitor for power factor improvement is equal to or higher than the rectified voltage of the AC power supply. The power converter according to claim 1.