JP2963355B2 - Power supply - Google Patents

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 for reducing a harmonic component of an input current by improving a power factor.

[0002]

2. Description of the Related Art A conventional switching regulator is disclosed, for example, in Japanese Patent Application Laid-Open No. 5-103468. 13 and 14 shows the circuit and the main current, in such a configuration, an AC power supply 2 (voltage V _AC) rectifying circuit 4
And the rectified voltage V _CC is increased by the transistor Q _S
Are turned on and off (switching) at high speed.

[0003] In this case, the transistor Q _S is in a section rectified voltage V _CC is higher than the terminal voltage of the partial smoothing capacitor C3 when turned on, the current I ₁ flows through the first primary winding N _I of the inverter transformer T1 with power is supplied to the secondary side, the smoothing capacitor C3 is charged the charging current I ₂ flows from the second primary winding N ₃ the smoothing capacitor C3. That is, the rectified voltage V _CC (= | AC input voltage V _AC
|) Is lower than the terminal voltage of the smoothing capacitor C3.
In b, the currents I ₁ and I ₂ do not flow.

Further, the rectified voltage V _CC is changed to a smoothing capacitor C3.
In the section a-b lower than the terminal voltage of
The discharge current I ₃ of the first primary winding N _I and the diode D
Therefore, power is supplied to the secondary side by the energy stored in the smoothing capacitor C3. That is, the current I ₃ does not flow in the rectified voltage V _CC is higher than the terminal voltage of the smoothing capacitor C3 section. The secondary side includes diodes D24 and D25, a choke coil CH, and a capacitor C2, and supplies an output voltage to a load _RL .

[0005]

However, in the conventional power supply, since the smoothing capacitor C3 and the rectifier circuit 4 are separated by the diode D and connected to the inverter transformer T1, the rectified voltage V _CC (= | AC input) Voltage V
_AC |) is lower than the terminal voltage of the smoothing capacitor C3.
Flows from the current I ₃ is a smoothing capacitor C3 in -b inverter transformer T1, the AC input current does not flow. Therefore, the conduction angle of the AC input current is reduced by the smoothing capacitor C3.
Is limited to less than 180 ° due to the terminal voltage, and the power factor is poor.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and it is an object of the present invention to improve a power factor by setting a conduction angle of an AC input current to 180 ° to reduce a harmonic component of the AC input current. It is an object of the present invention to provide a power supply device capable of performing the following.

[0007]

In order to achieve this object, the present invention provides a rectifier circuit for rectifying an AC voltage, an inverter circuit for switching a DC voltage rectified by the rectifier circuit to step up / down, and a rectifier circuit. and are connected in series between the inverter circuit, a smoothing capacitor for applying a DC voltage switching has been rectified by the discharge voltage and the rectifier circuit when turned to the inverter circuit, switching
Energy is stored when switching is on and switching is off
Charge the smoothing capacitor with the energy
And a choke coil .

The inverter circuit has an auxiliary winding of a transformer, and when the switching is off, the auxiliary winding charges a smoothing capacitor.
Is higher than the DC voltage rectified by the rectifier circuit.
And applying a current to the inverter circuit .

The present invention also provides a rectifier circuit for rectifying an AC voltage, a choke coil, a smoothing capacitor, and a transformer.
A step-down dither circuit for stepping down the DC voltage rectified by the rectifier circuit by the next winding and the switching means; charging when the switching means is on and returning the current to the AC side when the switching means is off; discharging when the switching means is off; to and having a capacitor for applying the energy to switch Yokukoiru.

[0010]

According to the power supply device of the present invention, the rectifier circuit and the inverter
The smoothing capacitor connected in series between the
The discharge voltage and the DC voltage rectified by the rectifier circuit
Applied to the inverter circuit.

Accordingly, the voltage applied to the inverter circuit is increased by the amount of the discharge voltage of the smoothing capacitor, since the conduction angle of the AC input current is 180 °, it improves the power factor
Thus , harmonic components of the AC input current can be reduced.

Also, according to the present invention, the conduction angle of the AC input current is 1
In the power supply circuit having a step-down dither circuit less than 80 °, that having a capacitor to return the current to the AC side with the switching means is charged when on.

Accordingly, the conduction angle of the AC input current becomes 180 °.
Thus, the power factor is improved and the harmonic component of the AC input current can be reduced.

[0014]

FIG. 1 is a circuit diagram showing one embodiment of a power supply device according to the present invention. In FIG. 1, an AC voltage (voltage V _AC , current I _AC ) having a period T supplied from an AC power supply 2 is full-wave rectified by a rectifier 4, and an output side of the rectifier 4 has one end of a smoothing capacitor C1 and an anode of a diode D1. It is connected to the. The inverter transformer (flyback transformer) T has a primary winding L11, an auxiliary winding L12, and a secondary winding L2. The other end of the smoothing capacitor C1 is a primary winding L
11, and the cathode of the diode D1 is connected to one end of the auxiliary winding L12. That is, the smoothing capacitor C1 is connected in series between the rectifier 4 and the transformer T.

[0015] The other end of the primary winding L11 is connected to the input side of the rectifier 4 through a switching transistor Q _S, the switching transistor Q _S is a high speed by the control signal pulse width is variable by the PWM control circuit 16 (period t = T _ON
+ T _OFF ) to turn on and off (switch). Here, the AC voltage V _AC frequencies 50 or 60 Hz, the on / off frequency of the switching transistor Q _S is several tens to several hundreds kHz.

A series circuit of a rectifier diode D2 and a smoothing capacitor C2 is connected to both ends of the secondary winding L2 of the transformer T, and a load _RL is connected to both ends of the smoothing capacitor C2. PWM control circuit 16 controls the pulse width of the switching transistor Q _S to a predetermined voltage by detecting the voltage across the smoothing capacitor C2 is turned on (duty ratio).

Next, the operation will be described with reference to FIGS. First, switching the transistor Q _S is turned on, the smoothing capacitor with flows in FIGS. 2 and 4 current I ₁ from the rectifier 4 as shown in the smoothing capacitor C1 → 1 winding L11 → switching transistor Q _S → rectifier 4 C1 discharges. No current flows through the diode D1 and the auxiliary winding L12 and the secondary winding L2. In this case, the rectified voltage V is applied to the primary winding L11 as shown in FIG.
_IN (= | ac input voltage V _AC |) voltage V _T of the charging voltage V _c is superimposed with the smoothing capacitor C1 is applied, since the energy is stored, the AC input current I _AC is AC input voltage V
_It flows at an _AC conduction angle of 180 °.

Next, when the switching transistor Q _S is turned off, FIGS. 3 and the auxiliary winding as shown in FIG. 4 L12
The energy stored in the side, with current I ₂ smoothing capacitor C1 flows to the smoothing capacitor C1 and the diode D11 side is charged, the current I ₃ is the secondary winding L
Flowing to the second side, the smoothing capacitor C2 is charged. Therefore, according to this embodiment, since the smoothing capacitor C1 is connected in series between the rectifier 4 and the transformer T, the rectified voltage V _IN and the charging of the smoothing capacitor C1 are provided on the primary winding L12 side of the transformer T. The voltage V _T on which the voltage V _c is superimposed is applied. Therefore, it is possible to improve the power factor by setting the conduction angle of the AC input current to 180 ° and reduce the harmonic component of the AC input current.

Next, a second embodiment will be described with reference to FIG. In this embodiment, a smoothing capacitor C1 is connected in series between a rectifier 4 and an inverter transformer (forward transformer) T1, and a choke coil CH1, a flywheel diode D11 and a rectifier diode D12 are also provided on the primary winding L1 side. Is provided. Further, on the secondary winding L2 side, a flywheel diode D13 and a choke coil CH2 are added to the circuit shown in FIG.

[0020] In such a configuration, the switching transistor Q _S is turned on, the choke coil CH currents I ₁ from the rectifier 4 to flow into the choke coil CH1 → rectifier diode D13 → the switching transistor Q _S side
With energy is stored in 1, the rectifier 4 current from I ₂ smoothing capacitor C1 → 1 winding L1 → switching transistor Q _S flows to the side smoothing capacitor C1 is discharged. Moreover, flows forward current I ₃ in the secondary side.

Next, when the switching transistor Q _S is turned off, the current I ₄ flows by the energy stored in the choke coil CH1 to charge the smoothing capacitor C1, and the current I ₅ flows on the secondary side. That is,
In this second embodiment, the switching transistor Q _S is the current of I ₁ + I ₂ in the case of on-flows as AC input current I _AC, the AC input current I _AC at the AC input voltage V _AC of T / 2 interval The conduction angle becomes 180 °.

Next, a third embodiment will be described with reference to FIGS. In this embodiment, a forward transformer T1 having primary windings L11 to L13 is used as shown in FIG. 7, and a partial smoothing capacitor C3 and diodes D14 and D15 are added to FIG. With such a configuration, when the switching transistor Qs is turned on, the current from the rectifier 4 is changed from the smoothing capacitor C1 to the primary winding L1 in the entire ON section as in the first embodiment.
1 → the switching transistor Qs → the rectifier 4 and the smoothing capacitor C1 is discharged. In a section where the rectified voltage V _IN is lower than the terminal voltage of the partial smoothing capacitor C3 in the ON section, the current from the partial smoothing capacitor C3 causes the primary winding L11 → switching transistor Qs
→ It flows to the diode D15 .

In this case, as shown in FIG. 8, the AC input current I _AC due to the smoothing capacitor C1 has a waveform inversely proportional to the AC instantaneous peak value, and the AC input current I _AC due to the partial smoothing capacitor C3 has a rectified voltage V _{Since IN} flows only in a section lower than the terminal voltage of the partial smoothing capacitor C3, the AC input current I _AC obtained by adding the two currents approaches a sine wave. Therefore, the power factor can be improved and the harmonic component can be reduced. Further, in the third embodiment, the partial smoothing capacitor C3 is discharged when the AC input is momentarily interrupted, so that the smoothing capacitor C1 is compared with the first and second embodiments.
However, there is an effect that a small capacity is sufficient.

Next, a fourth embodiment will be described with reference to FIGS. In this embodiment, as shown in FIG. 9, a choke coil CH, a smoothing capacitor C1, a diode D1
5, D16, with respect to known antihypertensive dither circuit comprising the primary winding L1 and the switching transistor Q _S of the flyback transformer T, capacitor C _P and the diode D17 for diverting current from the rectifier 4 are added ing.

The conduction angle using the step-down dither circuit is shown in FIG.
In a so 90 °, as shown, the switching transistor Q _S is the current from the rectifier 4 in this 90 ° intervals diode D17 → flowing in the input side of the step-down dither circuit → rectifier 4 on. Then, the flow in this embodiment, the switching transistor Q _S is turned on, the input side of the rectified voltage V _IN current I ₁ from the rectifier 4, which is proportional to the capacitor C _P → switching transistor Q _S → rectifier 4 in full period T Thus, the capacitor _CP is charged. The switching transistor Q _S is turned off, the energy in the choke coil CH and the charging voltage of the capacitor C _p by the exciting current of the primary winding L1 of the transformer T1 is discharged is accumulated.

In this case, the capacitor C_PAnd diode D
Current I flowing through 17₁Is the AC instantaneous as shown in FIG.
Since the waveform is proportional to the peak time, the step-down dither
Two currents, that is, the AC input power
Style I_ACApproaching a sine wave, thus improving the power factor
Thus, harmonic components can be reduced. Next, FIG.
A fifth embodiment will be described with reference to FIGS. This example
Now, as shown in FIG.
Iod D18, D19, flyback transformer T 1
Next windings L11 and L12 and switching transistor Q
_SSwitching regulator of partial smoothing system composed of
Capacitor C_pAnd its charging / discharging diode
D20 and D21 are added.

In this case, as shown in FIG.
_{In a} section where _IN is lower than the terminal voltage of the partial smoothing capacitor C3, the current by the partial smoothing capacitor C3 is the primary winding L1 → the switching transistor Qs → the diode D1.
9 , the conduction angle is less than 180 °. Then, the current I _l flowing through the capacitor Cp becomes proportional waveform and AC actual peak value in use shown in FIG. 11,
The combined current of the two currents approaches a sine wave.

[0028]

As described above, according to the present invention, the discharge voltage and the DC voltage rectified by the rectifier circuit are applied to the inverter circuit by the smoothing capacitor connected in series between the rectifier circuit and the inverter circuit. Then, the voltage applied to the inverter circuit increases by the discharge voltage of the smoothing capacitor, and the conduction angle of the AC input current becomes 180 °.
Therefore, the power factor can be improved and the harmonic component of the AC input current can be reduced.

Further, according to the present invention, the conduction angle of the AC input current is 1
In a power supply circuit having a step-down dither circuit of less than 80 °, a capacitor that is charged when the switching means is turned on and returns a current to the AC side has a conduction angle of the AC input current of 180 °, and therefore, The power factor can be improved and the harmonic component of the AC input current can be reduced.

Further, according to the present invention, the conduction angle of the AC input current is 1
In a power supply circuit having a partial smoothing circuit of less than 80 °,
And a capacitor that is charged when the switching means is turned on and returns the current to the AC side, so that the conduction angle of the AC input current becomes 180 °, thus improving the power factor and reducing the harmonic components of the AC input current. Can be reduced.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing an operation when switching is on in FIG. 1;

FIG. 3 is an explanatory diagram showing an operation when switching is off in FIG. 1;

FIG. 4 is a waveform diagram showing main currents when switching is turned on and off in FIG.

FIG. 5 is an explanatory diagram showing a conduction angle of an AC input current in the power supply device of FIG. 1;

FIG. 6 is a circuit diagram showing a second embodiment of the power supply device according to the present invention.

FIG. 7 is a circuit diagram showing a third embodiment of the power supply device according to the present invention.

FIG. 8 is an explanatory diagram showing a conduction angle of an AC input current in the power supply device of FIG. 7;

FIG. 9 is a circuit diagram showing a fourth embodiment of the power supply device according to the present invention.

FIG. 10 is an explanatory diagram showing a conduction angle of an AC input current in the power supply device of FIG. 9;

FIG. 11 is a circuit diagram showing a fifth embodiment of the power supply device according to the present invention.

FIG. 12 is an explanatory diagram showing conduction angles of an AC input current in the power supply device of FIG. 10;

FIG. 13 is a circuit diagram showing a conventional power supply device.

14 is an explanatory diagram showing a conduction angle of an AC input current in the power supply device of FIG.

[Explanation of symbols]

2: AC power supply 4: Rectifier circuit 16: PWM control circuit C1, C2, C3: Smoothing capacitors D1, D2, D11 to D21: Diode T, T1: Transformers L11 to L13, L1: Primary winding L2: Secondary winding line R _L: load Q _S: switching transistors CH, CH1, CH2: choke coil

Claims (3)

(57) [Claims] A rectifier circuit for rectifying an AC voltage; an inverter circuit for switching a DC voltage rectified by the rectifier circuit to step up / down the voltage; a rectifier circuit connected in series between the rectifier circuit and the inverter circuit; A smoothing capacitor for applying the discharge voltage and the DC voltage rectified by the rectifier circuit to the inverter circuit when on, storing energy when switching is on, and charging the smoothing capacitor with the energy when switching is off Power supply device having a choke coil. 2. A rectifier circuit for rectifying an AC voltage, an inverter circuit for switching a DC voltage rectified by the rectifier circuit to step up / down, and a serial connection between the rectifier circuit and the inverter circuit. When turned on, the discharge voltage and the DC voltage rectified by the rectifier circuit are applied to the inverter circuit, and a current is applied to the inverter circuit in a section where the terminal voltage is higher than the DC voltage rectified by the rectifier circuit. A power supply device comprising: a capacitor; and the inverter circuit includes an auxiliary winding of a transformer, and charges the smoothing capacitor by the auxiliary winding when switching is off. 3. A rectifier circuit for rectifying an AC voltage, a step-down dither circuit for reducing a DC voltage rectified by the rectifier circuit by a choke coil, a smoothing capacitor, a primary winding of a transformer, and switching means; When the switching means is on, the battery is charged and the current returns to the AC side, and when the switching means is off,
And a capacitor for discharging the energy and applying the energy to the choke coil.