JPH11196572A - Switching power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To practice switching with a predetermined arbitrary frequency while soft switching is practiced. SOLUTION: An input reactor L1; a tertiary winding N3 of a transformer Tr connected in series to a primary winding N1; a main switch Q1 connected in series to the tertiary winding N3; a diode D1 connected in reverse-parallel to the main switch Q1; a snubber capacitor Cs connected in parallel to the main switch Q1; a series circuit which consists of a resonance capacitor C2, a resonance reactor L2, and an auxiliary switch Q2, and through which the snubber capacitor Cs is discharged; a diode D3 connected between the junction of the winding N1 and the winding N3 and the auxiliary switch Q2; and a capacitor C1 connected in parallel to the winding N3 through the diode D3; are provided. By generating resonance at a arbitrary time with the switching of the auxiliary switch Q2, the soft switching of the switches Q1 and Q2 can be practiced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply for supplying power from a DC power supply to a load via a transformer or the like.

[0002]

2. Description of the Related Art FIG. 19 shows a conventional example of a flyback type switching power supply. That is, a series circuit of the input reactor L1, the transformer primary winding N1, and the switch Q1 is
Connected in parallel to a rectifier Rec as a DC power supply,
The switch Q1 is configured by connecting a snubber capacitor Cs in parallel. The operation is to store energy in the primary winding N1 when the switch Q1 is on, and to release the stored energy from the secondary winding N2 when the switch Q1 is off. The output voltage is adjusted by adjusting ON and OFF of Q1. Further, in this circuit, by causing the leakage inductance of the transformer primary winding N1 and the snubber capacitor Cs connected in parallel to the switch Q1 to resonate, the switch Q1 is turned on when the voltage of the snubber capacitor Cs becomes the lowest. , So-called soft switching (zero voltage switching) is realized. The reason why soft switching is performed is to reduce loss and suppress generated noise.

When the power factor improving switch Q3 is turned on, an input power supply is short-circuited via the input reactor L1, and an input current flows. When the power factor improving switch Q3 is turned off, the energy stored in the input reactor L1 is discharged to the capacitor (electrolytic capacitor) C1.
At this time, by turning on / off the power factor improving switch Q3 in the entire region, the input current can flow even when the input voltage is low, so that the power factor can be improved.

[0004]

However, FIG.
In such a switching power supply device, soft switching is performed by the resonance between the leakage inductance of the transformer primary winding N1 and the snubber capacitor Cs.
The off period of the switch Q1 must be a fixed time determined by the leakage inductance of the transformer primary winding N1 and the resonance period of the snubber capacitor Cs. As a result, only the ON period is adjusted to adjust the output voltage, which causes a problem that the switching frequency is not constant. Further, when used as a power source for televisions (TVs) and displays, the switching frequency is synchronized with the deflection frequency. However, there is a problem that the switching frequency cannot be applied to such a variable frequency power source.

Further, in the conventional method, since the power factor improving switch Q3 and the main switch Q1 are individually switched, there arises a problem that noise generated from the switching power supply increases. Further, there is a problem that the efficiency is reduced because the converters are arranged in two series. Therefore, an object of the present invention is to enable switching at an arbitrary frequency set while maintaining a soft switching method, and to improve a power factor by a simple method.

[0006]

In order to solve such a problem, according to the first aspect of the present invention, a secondary winding of a transformer having a primary winding and a secondary winding and connected between a DC power supply is provided. Rectification
In a switching power supply device connected with a smoothing circuit, an input reactor, a tertiary winding connected in series to a primary winding of the transformer, a main semiconductor switch connected in series to the tertiary winding, A first diode connected in antiparallel with the semiconductor switch, a snubber capacitor connected in parallel with the main semiconductor switch, a series of a resonance capacitor for discharging electric charge of the snubber capacitor, a resonance reactor, and an auxiliary semiconductor switch; Circuit and
A second diode connected in anti-parallel to the auxiliary semiconductor switch, a third diode connected between the connection point between the primary winding and the tertiary winding and the auxiliary semiconductor switch, and a third diode connected to the auxiliary semiconductor switch; And a capacitor connected in parallel to the primary winding through the capacitor.

According to the first aspect of the invention, a series circuit of a resonance reactor and an auxiliary switch can be used instead of the series circuit of the resonance capacitor, the resonance reactor and the auxiliary semiconductor switch (the invention of the second aspect). In the first or second aspect of the invention, a reactor can be used instead of the transformer tertiary winding (the third aspect of the invention), or the third diode can be omitted (the fourth aspect of the invention). Invention).

According to a fifth aspect of the present invention, there is provided a switching power supply device comprising a primary winding and a secondary winding, and a rectifying / smoothing circuit connected to a secondary winding of a transformer connected between DC power supplies. An input reactor, a main semiconductor switch connected in series to a primary winding of the transformer, a first diode connected in anti-parallel to the main semiconductor switch,
A snubber capacitor connected in parallel to the main semiconductor switch, a series circuit of a resonance capacitor for discharging the electric charge of the snubber capacitor, a resonance reactor and an auxiliary semiconductor switch, and a second circuit connected in antiparallel to the auxiliary semiconductor switch. And two diodes. In the first to fifth aspects of the present invention, a newly provided transformer quaternary winding can be used as the input reactor instead of the input reactor (the invention of the sixth aspect).

Further, according to the present invention, there is provided a switching power supply device comprising a primary winding and a secondary winding, and a rectifier / smoothing circuit connected to a secondary winding of a transformer connected between the DC power supplies. An input reactor, a main semiconductor switch connected in series to a primary winding of the transformer, a first diode connected in anti-parallel to the main semiconductor switch, and a primary winding and a main semiconductor switch of the transformer. A series circuit of a capacitor and an auxiliary semiconductor switch connected in parallel to the series circuit of the above, a second diode connected in anti-parallel to the auxiliary semiconductor switch, and a connection point between the primary winding of the transformer and the main semiconductor switch. And a third diode connected between the auxiliary semiconductor switch and the auxiliary semiconductor switch. According to the seventh aspect of the present invention, a transformer tertiary winding newly provided can be used as the input reactor instead of the input reactor (the invention of the eighth aspect), or the input reactor is removed and the capacitor is removed. And the auxiliary semiconductor switch can be replaced by a series circuit of a capacitor, a transformer tertiary winding, and an auxiliary semiconductor switch.

In a tenth aspect of the present invention, an electrolytic capacitor and a rectifier for converting an AC voltage to a DC voltage are connected in parallel with the series circuit in which a semiconductor switch is connected in series with the primary winding of the transformer. A rectifying / smoothing circuit is connected between the secondary windings to turn on and off the semiconductor switch to supply DC power to a load. In a switching power supply, a tertiary transformer is connected between a connection point between the rectifier and the electrolytic capacitor. A series circuit of a winding and a diode for reverse recovery is connected. In this way, when the semiconductor switch is turned on, a voltage having a polarity opposite to that of the reverse recovery diode is generated in the transformer tertiary winding, and as a result, the reverse recovery diode reversely recovers and cuts off the current. The rectifier can be constituted by a general rectifier diode, and cost reduction can be achieved.

According to the eleventh aspect of the present invention, an electrolytic capacitor and a rectifier for converting an AC voltage to a DC voltage are connected in parallel with the series circuit in which the first semiconductor switch is connected in series with the primary winding of the transformer. A rectifying / smoothing circuit is connected between the secondary windings of the transformer to turn on and off the first semiconductor switch to supply DC power to a load. A series circuit of a quaternary winding and a diode is connected, and a series circuit of a tertiary winding of a transformer and a second semiconductor switch is connected in parallel with an electrolytic capacitor.

According to the eleventh aspect, since the discharge of the quaternary winding of the transformer is performed via the diode, the electrolytic capacitor, the rectifier, and the AC power supply, even if the input voltage is lower than the electrolytic capacitor voltage. A current flows, and as a result, the conduction angle increases and the power factor is improved. At this time,
Since the power supply voltage and the voltage generated in the quaternary winding of the transformer are applied to the electrolytic capacitor, the electrolytic capacitor can be charged with a voltage higher than the power supply voltage peak value. Furthermore, even when the power supply voltage is low and the voltage generated in the quaternary winding of the transformer is applied, the voltage of the electrolytic capacitor does not reach the voltage of the electrolytic capacitor. Is directly connected to the rectifier, so that current can flow, and as a result, the conduction angle can be widened. I am trying to do it.

According to a twelfth aspect of the present invention, in a switching power supply unit in which a primary winding of a transformer and a main semiconductor switch are connected in series with a DC power supply, a resonance inductance, a resonance capacitor and an auxiliary capacitor are provided for the main semiconductor switch. A series circuit with the semiconductor switch is connected in parallel, and when the output power including the standby mode is small, the operation is performed by turning on and off only the auxiliary semiconductor switch. According to the twelfth aspect of the invention, the resonance inductance can be a tertiary winding of a transformer.
3 invention).

According to a fourteenth aspect of the present invention, a control integrated circuit for driving and controlling the semiconductor switch is connected to the semiconductor switch of the switching power supply in which a primary winding of a transformer and a semiconductor switch are connected in series with a DC power supply. A main power supply for supplying power during operation, and a control for driving and controlling the semiconductor switch of the switching power supply in which a primary winding of a transformer and a semiconductor switch are connected in series with the DC power supply in series. A sub-power supply for connecting the integrated circuit and supplying power during standby; providing a semiconductor switch for the main power supply and an integrated circuit for controlling the same and a semiconductor switch for the sub-power supply and an integrated circuit for controlling the same; It is stored in a package. According to the invention of claim 14, at least one of the main power supply and the sub power supply can be the switching power supply device according to any one of claims 1 to 13 (claim 15).
Invention).

According to a sixteenth aspect of the present invention, a switching power supply device in which a primary winding of a transformer and a semiconductor switch are connected in series with a DC power supply is provided as a main power supply and a sub power supply, and the semiconductor switch of the main power supply and the sub power supply are provided. A common control integrated circuit for controlling a power supply semiconductor switch is integrated with these semiconductor switches and housed in the same package. Claim 16
According to the present invention, at least one of the main power supply and the sub power supply can be the switching power supply device according to any one of claims 1 to 13 (invention of claim 17).

[0016]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. Input reactor L for DC input
The primary winding N1, the tertiary winding N3, and the main switch Q of the transformer Tr are connected in series with the input reactor L1.
1 is connected. An antiparallel diode D1 and a snubber capacitor Cs are connected in parallel to the main switch Q1. A series circuit of a resonance capacitor C2, a resonance reactor L2, and an auxiliary switch Q2 is connected in parallel to the snubber capacitor Cs, and a diode D2 is connected in anti-parallel to the auxiliary switch Q2. A diode D3 is connected between a connection point between the primary winding N1 and the tertiary winding N3 and the auxiliary switch Q2, and a capacitor C1 is connected in parallel with the primary winding N1 via the diode D3. In addition,
DC indicates a DC power supply.

FIG. 2 is a diagram for explaining the operation of FIG. First, as shown in FIG. 2, the auxiliary switch Q2 is turned on before the main switch Q1 is turned on, and generates a series resonance of the snubber capacitor Cs, the resonance capacitor C2, and the resonance reactor L2 via the auxiliary switch Q2. At this time, the current of the auxiliary switch Q2 is supplied from the power supply DC, the capacitor C1, and the snubber capacitor Cs via the resonance reactor L2, the input reactor L1, the transformer primary winding N1, and the transformer tertiary winding N3, so that the current suddenly increases. No flow occurs, and the auxiliary switch Q2 performs zero current switching (ON). The main switch Q1 is turned on when the voltage of the snubber capacitor Cs (voltage of the main switch Q1) becomes zero due to the series resonance of the snubber capacitor Cs, the resonance capacitor C2, and the resonance reactor L2.
Zero voltage switching (ON) of the main switch Q1 is performed.

When the main switch Q1 is turned on, the series resonance of the snubber capacitor Cs, the resonance capacitor C2, and the resonance reactor L2 passing through the auxiliary switch Q2 causes the diode D2 connected in anti-parallel to the main switch Q1 and the auxiliary switch Q2. The auxiliary switch Q2 is switched to the series resonance of the resonant capacitor C2 and the resonance reactor L2, and the auxiliary switch Q2 is turned off while the current flows through the diode D2 due to the series resonance. Perform Next, when the main switch Q1 is turned off, the current flowing in the main switch Q1 flows to the snubber capacitor Cs, the voltage of the snubber capacitor Cs (the voltage of the main switch Q1) gradually increases, and the off of the main switch Q1 is zero. Voltage switching (off) is performed. At this time, during the ON period of the main switch Q1, the capacitor C1
The electric charge of the resonance capacitor C2 stored through the circuit is regenerated to the capacitor C1. The energy stored in the leakage inductance of the primary winding N1 is stored in the capacitor C1 via the diode D3.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention, in which the resonance capacitor C2 of FIG. 1 is removed and short-circuited. Here, the auxiliary switch Q2
1 is turned on before the main switch Q1 is turned on, as in the case of FIG. 1, and generates a series resonance of the snubber capacitor Cs and the resonance reactor L2 via the auxiliary switch Q2. At this time, the current of the auxiliary switch Q2 is supplied from the power supply DC, the capacitor C1, and the snubber capacitor Cs via the resonance reactor L2, the input reactor L1, the transformer primary winding N1, and the transformer tertiary winding N3, so that the current suddenly increases. No flow occurs, and the auxiliary switch Q2 performs zero current switching (ON). And the snubber capacitor Cs
When the voltage of the snubber capacitor Cs (the voltage of the main switch Q1) becomes zero due to the series resonance between the main switch Q1 and the resonance reactor L2, the main switch Q1 is turned on to perform zero voltage switching (on) of the main switch Q1. . Next, when the main switch Q1 is turned off, the current flowing in the main switch Q1 flows to the snubber capacitor Cs, the voltage of the snubber capacitor Cs (the voltage of the main switch Q1) gradually increases, and the off of the main switch Q1 is zero. Voltage switching (off) is performed. At this time, the energy stored in the leakage inductance of the primary winding N1 is stored in the capacitor C1 via the diode D3.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention, in which the tertiary winding N3 in FIG. 1 is changed to a reactor L3. Here, the auxiliary switch Q2
1 is turned on before the main switch Q1 is turned on, as in the case of FIG. 1, and generates a series resonance of the snubber capacitor Cs, the resonance capacitor C2 and the resonance reactor L2 via the auxiliary switch Q2. At this time, the current of the auxiliary switch Q2 passes through the resonance reactor L2, the primary winding N1 of the transformer, and the reactor L3, and passes through the power supply DC and the capacitor C2.
1 and supplied from the snubber capacitor Cs, the current does not flow rapidly, and the auxiliary switch Q2 is switched to zero current switching (ON). The following operations are the same as those in FIG. Also in the case of FIG. 3, it goes without saying that the tertiary winding N3 can be changed to the reactor L3.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention, in which the diode D3 in FIG.
3 is short-circuited. Auxiliary switch Q
1 is turned on before the main switch Q1 is turned on, as in the case of FIG. 1, and passes through the auxiliary switch Q2 to the snubber capacitor Cs, the resonance capacitor C2 and the resonance reactor L2.
Generates a series resonance. At this time, the auxiliary switch Q2
Is supplied from the power source DC, the capacitor C1 and the snubber capacitor Cs via the resonance reactor L2 and the input reactor L1, and therefore does not flow rapidly, and the auxiliary switch Q2 is switched to zero current (ON). Then, the series resonance of the snubber capacitor Cs, the resonance capacitor C2, and the resonance reactor L2 causes the snubber capacitor Cs
When the voltage of s (voltage of the main switch Q1) becomes zero, the main switch Q1 is turned on, thereby performing zero-voltage switching (on) of the main switch Q1.

When the main switch Q1 is turned on, the series resonance of the snubber capacitor Cs, the resonance capacitor C2, and the resonance reactor L2 via the auxiliary switch Q2 causes the diode D2 connected in anti-parallel to the main switch Q1 and the auxiliary switch Q2. It switches to the series resonance of the resonance capacitor C2 and the resonance reactor L2 that have passed through, and turns off the auxiliary switch Q2 during a period when a current flows through the diode D2 due to this series resonance, thereby zero voltage switching (off) of the auxiliary switch Q2. Perform Next, when the main switch Q1 is turned off, the current flowing in the main switch Q1 flows to the snubber capacitor Cs, the voltage of the snubber capacitor Cs (the voltage of the main switch Q1) gradually increases, and the off of the main switch Q1 is zero. Voltage switching (off) is performed. At this time, during the ON period of the main switch Q1, the capacitor C1
The electric charge of the resonance capacitor C2 stored through the circuit is regenerated to the capacitor C1.

FIG. 6 is a circuit diagram showing a fifth embodiment of the present invention. Here, a transformer primary winding N1 and a main switch Q1 are connected in series to the DC input, and an anti-parallel diode D1 and a snubber capacitor Cs are connected in parallel to the main switch Q1. Further, a series circuit of the resonance capacitor C2, the resonance reactor L2 and the auxiliary switch Q2 is connected in parallel to the snubber capacitor Cs, and a diode D2 is connected in anti-parallel to the auxiliary switch Q2. The auxiliary switch Q2 is turned on before the main switch Q1 is turned on, as in the case of FIG.
2, the snubber capacitor Cs and the resonance capacitor C
2 and the resonance reactor L2 generate series resonance.
At this time, the current of the auxiliary switch Q2 is
2, the current is supplied from the snubber capacitor Cs and does not flow rapidly, and the auxiliary switch Q2 is switched to zero current switching (ON). Then, the snubber capacitors Cs,
When the voltage of the snubber capacitor Cs (the voltage of the main switch Q1) becomes zero due to the series resonance of the resonance capacitor C2 and the resonance reactor L2, the main switch Q1 is turned on. On).

When the main switch Q1 is turned on, the series resonance of the snubber capacitor Cs, the resonance capacitor C2, and the resonance reactor L2 via the auxiliary switch Q2 causes the diode D2 connected in anti-parallel to the main switch Q1 and the auxiliary switch Q2. It switches to the series resonance of the resonance capacitor C2 and the resonance reactor L2 that have passed through, and turns off the auxiliary switch Q2 during a period when a current flows through the diode D2 due to this series resonance, thereby zero voltage switching (off) of the auxiliary switch Q2. Perform Next, when the main switch Q1 is turned off, the current flowing in the main switch Q1 flows to the snubber capacitor Cs, the voltage of the snubber capacitor Cs (the voltage of the main switch Q1) gradually increases, and the off of the main switch Q1 is zero. Voltage switching (off) is performed.

FIG. 7 is a circuit diagram showing a sixth embodiment of the present invention, in which the input reactor L1 of FIG. 1 is changed to a transformer quaternary winding. Here, as in the case of FIG. 1, the auxiliary switch Q2 is turned on before the main switch Q1 is turned on, and generates a series resonance of the snubber capacitor Cs, the resonance capacitor C2 and the resonance reactor L2 via the auxiliary switch Q2. At this time, the current of the auxiliary switch Q2 is transmitted to the resonance reactor L2, the transformer quaternary winding N4, the transformer primary winding N1, and the transformer tertiary winding N
3, the power is supplied from the power source DC, the capacitor C1, and the snubber capacitor Cs, so that the current does not flow rapidly, and the auxiliary switch Q2 is switched to zero current (ON).
The following operations are the same as those in FIG. In FIGS. 3, 4, and 5, it goes without saying that a transformer quaternary winding can be used instead of input reactor L1.

It is desirable that the switching power supply has a high power factor. Hereinafter, an example for improving the power factor will be described. FIG. 8 is a circuit diagram showing a seventh embodiment of the present invention. An input reactor L1 is connected to the DC input, and a series circuit of the primary winding N1 of the transformer Tr and the main switch Q1 is connected in series with the input reactor L1. This main switch Q1 has a diode D connected in anti-parallel.
1 is connected in parallel with a capacitor C1 and an auxiliary switch Q in a series circuit of the primary winding N1 of the transformer Tr and the main switch Q1.
The auxiliary switch Q2 includes a diode D2 in anti-parallel, and a primary winding N1 of the transformer Tr.
A diode D3 is connected between the connection point of the main switch Q1 and the auxiliary switch Q2.

The operation is as follows. First, the main switch Q1 is turned on to flow an input current. As a result, the input current can flow even when the input voltage is low, and the power factor can be improved. When the main switch Q1 is off, a part of the excitation energy of the transformer Tr is
The current is accumulated via a diode D3 in a capacitor C1 connected in parallel with the primary winding N1 of the transformer Tr. next,
By turning on the auxiliary switch Q2, the capacitor C
The energy stored in the input reactor L1 is transferred to the transformer Tr by transferring the energy stored in 1 to the input reactor L1 via the rectifier Rec and turning off the auxiliary switch Q2. As a result, the energy stored in the capacitor C1 can be released to the load.

FIG. 9 shows a first modification of FIG. FIG. 9 is characterized in that the input reactor L1 in FIG. 8 is changed to a transformer tertiary winding N3 and this is used as an input reactor. The operation is almost the same as that in FIG. FIG. 10 shows a second modification of FIG. This removes the input reactor L1 from FIG.
The series circuit of the capacitor C1 and the auxiliary switch Q2 is composed of the capacitor C1, the transformer tertiary winding N3, and the auxiliary switch Q2.
The feature is that it has been replaced with a series circuit with
Is the same as Although the example of the flyback converter has been described above, the present invention can be similarly applied to the case of a forward converter.

FIG. 11 is a circuit diagram showing an eighth embodiment of the present invention. The circuit shown in the figure includes a series circuit of a transformer tertiary winding N3 connected to a rectifier Rec that converts an AC voltage to a DC voltage and a high-speed reverse recovery (recovery) diode D2, a transformer primary winding N1 and a transformer tertiary winding. Consisting of an electrolytic capacitor C1 connected between a series circuit of N3 and a diode D2, a semiconductor switch Q1 connected in series with the transformer primary winding N1, and a diode D1 connected in anti-parallel to the semiconductor switch Q1. Is done.

The operation will be described. When the semiconductor switch Q1 is turned on in FIG. 11, a voltage is generated in the transformer tertiary winding N3 with a polarity opposite to that of the high-speed recovery diode D2, thereby reversely recovering the diode D2 and interrupting the current. Therefore, the rectifier Rec includes the diode D
No current flows due to the reverse recovery of No. 2, so that the rectifier Rec does not need to have a high-speed reverse recovery characteristic, and a general low-speed rectifier diode is sufficient, and the cost can be reduced.

FIG. 12 is a circuit diagram showing a ninth embodiment of the present invention. The circuit shown in FIG.
And a diode D connected in anti-parallel to the semiconductor switch Q1.
1, the transformer primary winding N1 and the first semiconductor switch Q
1 and a transformer quaternary winding N connected in parallel to the series circuit
4, a series circuit of a diode D3 and an electrolytic capacitor C1, a series circuit of a transformer tertiary winding N3 and a second semiconductor switch Q2 connected in parallel to the electrolytic capacitor C1, and anti-parallel to the second semiconductor switch Q2. And a connected diode D2.

First, the operation by the switching of the semiconductor switch Q1 will be described. Transformer primary winding N1
When the first semiconductor switch Q1 connected in series with the first is turned on, energy is accumulated in the transformer primary winding N1. At this time, the rectifier Re is connected to the transformer quaternary winding N4.
A voltage is generated with a polarity such that the c side is positive and the electrolytic capacitor C1 side is negative, preventing charging of the electrolytic capacitor C1. When the semiconductor switch Q1 is turned off, the energy stored in the transformer primary winding N1 is released to the secondary winding N2 and the quaternary winding N4 of the transformer Tr. Then, the energy released to the transformer secondary winding N2 is supplied to the load via the rectifier Rec1. Further, in the transformer quaternary winding N4, a voltage is generated with a polarity having a negative polarity on the rectifier Rec side and a positive polarity on the electrolytic capacitor C1 side, discharges energy to the electrolytic capacitor C1 via the diode D3, and charges it. .

Next, the operation by the switching of the second semiconductor switch Q2 will be described. When the semiconductor switch Q2 is turned on, the electrolytic capacitor C1 is discharged via the transformer tertiary winding N3. Due to this discharge current, energy is stored in the transformer tertiary winding N3. At this time, the rectifier Rec side is positive and the transformer quaternary winding N4 is positive.
A voltage is generated with a polarity that makes the electrolytic capacitor C1 side negative,
This prevents charging of the electrolytic capacitor C1. Semiconductor switch Q
2, the energy stored in the transformer tertiary winding N3 is transferred to the secondary winding N2 and the quaternary winding N of the transformer Tr.
It is released to 4. Then, the energy released to the transformer secondary winding N2 is supplied to the load via the rectifier Rec1. A rectifier R is connected to the transformer quaternary winding N4.
A voltage is generated with a polarity such that the ec side is negative and the electrolytic capacitor C1 side is positive.
Release energy to 1 and charge it.

The discharge of the transformer quaternary winding N4 due to the switching of the first semiconductor switch Q1 or the second semiconductor switch Q2 is performed by the transformer quaternary winding N4 → diode D
3 → Electrolytic capacitor C1 → Rectifier Rec → AC power supply AC
Therefore, even when the voltage of the AC power supply AC is lower than the electrolytic capacitor C1, the input current flows, so that the conduction angle increases and the power factor can be improved. At this time, the voltage generated in the transformer quaternary winding N4 is added to the input voltage of the electrolytic capacitor C1, and the electrolytic capacitor C1 can be charged with a voltage higher than the input voltage peak value. Also, even when the voltage of the AC power supply AC is low and the voltage generated in the transformer quaternary winding N4 is applied, the voltage of the electrolytic capacitor C1 does not reach and the charging of the electrolytic capacitor C1 is not performed. Since the series circuit of the line N1 and the first semiconductor switch Q1 is directly connected to the rectifier Rec, current can flow, and as a result, the conduction angle can be increased. The switching operations of the first semiconductor switch Q1 and the second semiconductor switch Q2 have been described separately. However, even if the first semiconductor switch Q1 and the second semiconductor switch Q2 are simultaneously switched (on and off), There is no problem at all.

By the way, in a TV or a portable device, there is a very small load condition called a standby mode of about 1/100 or less of the rated load. When the power is adjusted by the conventional circuit as shown in FIG. 19 under such a light load condition, the efficiency of the converter at a light load is significantly reduced due to the following problems. 1/100 to drive with a switch equivalent to the rated load
The switch driving power is large for a moderate load. As in the case of the rated load, the transformer is excited by a rectangular wave, and a current having a short on-period and a large peak value flows. Therefore, the copper loss of the transformer becomes large when the load is about 1/100. As described above, when the driving power and the copper loss in the standby mode of the conventional circuit are increased, the battery is drastically consumed in the case of a portable device or the like, and the operation period is shortened. In addition, TV
In such devices, there is a problem that power consumption regulations are not satisfied.

FIG. 13 is a circuit diagram showing a tenth embodiment capable of coping with the above problem. This example is characterized in that a series circuit of a resonance reactor L1, a resonance capacitor C2 and an auxiliary switch Q2 is connected in parallel with the switch Q1. As the auxiliary switch Q2, a switch that is about 1/10 of the rating of the main switch Q1 is used. The operation will be described. That is, during rated load operation, power is stored in the transformer Tr by switching of the main switch Q1. At this time, by turning on the auxiliary switch Q2 before turning on the main switch Q1, the charge of the capacitor Cs connected in parallel to the main switch Q1 can be discharged via the resonance capacitor C2 and the resonance reactor L1. , The main switch Q1 can be turned on from the state without voltage.

When the load is light, such as in the standby mode, only the auxiliary switch Q2 is switched and the main switch Q1 is kept off. At this time, a current flows through the auxiliary switch Q2 through a series circuit of the resonance capacitor C2 and the resonance reactor L1 in addition to the primary winding N1 of the transformer Tr. In this case, the operation is such that the resonance capacitor C2 is connected in series with the auxiliary switch Q2, so that the operation is a current resonance circuit. When the auxiliary switch Q2 is turned on, a current flows through the path of the transformer primary winding N1, the resonance reactor L1, the resonance capacitor C2, and the auxiliary switch Q2. At this time, the voltage of the transformer primary winding N1 decreases as the voltage of the resonance capacitor C2 increases. Capacitor C2
When the voltage rises above the input voltage, a current starts to occur, and the polarity of the voltage applied to the transformer primary winding N1 is inverted. When the transformer secondary voltage becomes higher than the output voltage Vo, the diode D1 conducts, and the energy stored in the transformer is released to the load.

During rated operation when the main switch Q1 is turned on,
The input voltage is directly applied to the transformer primary winding N1, and a triangular wave current flows. When only the auxiliary switch Q2 is operated, the current is determined by the impedance of the resonance capacitor C2, the transformer excitation inductance, and the resonance reactor L1. In this case, the resonance capacitor is
With a small capacity corresponding to a load of about 1/100 times, a current smaller than the peak value of the triangular wave can flow. Accordingly, since the output can be performed with a current having a smaller peak value than when the main switch is used, it is possible to reduce the transformer loss and the element conduction loss.
The rating of the auxiliary switch Q2 is 1 / the rating of the main switch.
Since the power is about 10 times, the driving power at the time of the light load operation is about 1/10 times that at the time of the rated operation.

FIG. 14 is a circuit diagram showing an eleventh embodiment. The difference from FIG. 13 lies in that a tertiary winding N3 of a transformer is used instead of the resonance reactor L1.
The operation of this circuit is almost the same as that of FIG. 13, except that when the auxiliary switch Q2 is turned on, the transformer primary winding N
1 and the tertiary winding N3 are in series. That is, since the excitation inductance is proportional to the square of the number of turns, the excitation inductance is greatly increased by slightly winding the tertiary winding, thereby making it possible to easily reduce the current peak value. That is, in the case of FIG.
Is a part as a resonance reactor at the time of light load operation. In FIG. 14, this can be replaced by adding only a few windings to the transformer, and the number of parts can be reduced.

FIGS. 13 and 14 show an example in which a light load (standby mode) operation can be performed with one circuit, but two circuits are generally used. FIG. 15 is a circuit diagram showing such an example. This is because a main power supply including a capacitor C1, a transformer Tr1, an integrated circuit (also referred to as a power IC1), diodes D5, D6, and capacitors C3 and C4, and a capacitor C11, a transformer Tr2, a power IC2, a diode D7, And a sub-power supply composed of a capacitor C4. The power IC1
Is composed of a MOSFET Q1 and a control IC1, and the power IC2 is composed of a MOSFET Q11 and a control IC2.

In the above configuration, when a device (not shown) is operating, the MOSFET Q1 is turned on and off, an AC voltage is applied to the transformer Tr1, and a main circuit power supply including a diode D5 and a capacitor C3, DC power is supplied to a CPU power supply composed of D6 and capacitor C4. The control IC 1 detects the output voltage and, based on the result of comparison with the command value, the MOSFET Q
By adjusting the on / off ratio of 1, the main circuit power supply is controlled to be constant. On the other hand, in the standby mode in which the apparatus does not operate and only the CPU operates, only the MOSFET Q11 is turned on and off without driving the MOSFET Q1, and the transformer T
An AC voltage is applied to r2 to supply DC power only to the CPU power supply including the diode D7 and the capacitor C5. By doing so, the power consumption in the standby mode in which only the CPU operates is reduced to several watts or less, and various energy regulations and the like are cleared.

FIG. 16 shows a configuration example of the power IC shown in FIG. 1A shows a power IC 1 and FIG. 1B shows a power IC.
2 shows a chip having a copper pattern formed on an insulating substrate. In this example, it is necessary to insulate the terminal block and the chip and the case and the chip for each package. Therefore, the configuration is as shown in FIG. FIG. 17 shows a configuration example of a power IC according to the present invention. As is clear from the figure, the power IC1 and the power IC2 are formed on the same insulating substrate, and the insulating substrate is made common, so that the size is reduced and the price is reduced. In FIG. 17, the power IC1 and the power IC2 are configured on the same insulating substrate, but may be configured as shown in FIG. That is, attention is paid to the fact that the control ICs 1 and 2 can have substantially the same configuration in terms of function, and the control ICs 1 and 2 are integrated into one (shared).

In the above description, the power source to be integrated is shown in FIG.
Although the switching power supply is a general switching power supply as shown in FIG. 5, it goes without saying that the various switching power supplies described with reference to FIGS. 13 and 14
When the standby mode operation can be performed by the auxiliary switch as described above, the control IC may be provided corresponding to the main switch and the auxiliary switch, or may be provided in common with the main switch and the auxiliary switch.

[0044]

According to the first to sixth aspects of the present invention, the switching element can be switched at an arbitrary set frequency while performing soft switching. As a result, the following advantages 1) to 3) are obtained. 1) Since switching is performed at zero voltage and zero current, switching loss is reduced. 2) dv / dt at the time of switching is reduced, and noise is reduced. 3) It can be used for a power supply for synchronizing a switching frequency with a deflection frequency in a power supply for a television or a display. According to the eighth and ninth aspects of the present invention, not only the power factor can be improved and noise is reduced, but also the energy stored in the primary-side capacitor (C1) is released to the load during an instantaneous stop. Therefore, there is an advantage that output voltage compensation can be easily performed.

According to the tenth aspect of the present invention, the primary side of the transformer can be constituted by one high-speed recovery diode, and the rectifier can be constituted by a general rectifier diode. As a result, it becomes cheap. According to the eleventh aspect, the input current can flow in the entire region, and the power factor can be improved. Also, since the electrolytic capacitor voltage can be higher than the input voltage peak value,
Output voltage compensation during a momentary power failure can be easily performed.

According to the twelfth and thirteenth aspects of the present invention, a) the driving power in the standby mode can be smaller than the rating of the auxiliary switch, so that the power consumption can be reduced and the operating time can be prolonged. This makes it possible to satisfy the power consumption regulations of TV devices and the like. B) Conventionally, a switching power supply with a 1/100 rating is generally installed separately in order to satisfy the above regulations. According to the invention of claims 12 to 13, a separately installed lower power supply becomes unnecessary. In addition, the size, weight and cost of the device can be reduced.

According to the fourteenth and fifteenth aspects of the present invention, the main power switch and its control IC and the sub power switch and its control IC are housed in the same package. In comparison, a package member such as an insulating substrate can be omitted, and downsizing and cost reduction can be realized. According to the invention of claims 16 and 17, by using one control IC and sharing it for the main power supply and the sub power supply, it is possible to further reduce the size and cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of FIG. 1;

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

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

FIG. 7 is a circuit diagram showing a sixth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a seventh embodiment of the present invention.

FIG. 9 is a circuit diagram showing a modification of the seventh embodiment of the present invention.

FIG. 10 is a circuit diagram showing another modified example of the seventh embodiment of the present invention.

FIG. 11 is a circuit diagram showing an eighth embodiment of the present invention.

FIG. 12 is a circuit diagram showing a ninth embodiment of the present invention.

FIG. 13 is a circuit diagram showing a tenth embodiment of the present invention.

FIG. 14 is a circuit diagram showing an eleventh embodiment of the present invention.

FIG. 15 is a circuit diagram showing a general example of a switching power supply performing a light load operation.

FIG. 16 is a configuration diagram showing an example of integration of FIG. 15;

FIG. 17 is a configuration diagram showing an example of integration according to the present invention.

FIG. 18 is a configuration diagram showing another example of integration according to the present invention.

FIG. 19 is a circuit diagram showing a conventional example.

[Explanation of symbols]

Rec, Rec1 rectifier, L1, L2, L3 ... reactor, C1, C2, C3, C4, C5, C11, Cs ...
Capacitors, Q1, Q2, Q3, Q11 ... semiconductor switches, D1, D2, D3, D4, D5, D6, D7 ... diodes, Tr, Tr1, Tr2 ... transformers, N1 ... transformer primary winding, N2 ... transformer secondary winding Line, N3 ... Transformer tertiary winding, N4 ... Transformer quaternary winding, DC ... DC power supply.

Claims (17)

[Claims] 1. A switching power supply device comprising a primary winding and a secondary winding and a rectifier / smoothing circuit connected to a secondary winding of a transformer connected between a DC power supply, comprising: an input reactor; A tertiary winding connected in series to the primary winding, a main semiconductor switch connected in series to the tertiary winding, a first diode connected in anti-parallel to the main semiconductor switch, and a main semiconductor switch. , A series circuit of a resonance capacitor, a resonance reactor, and an auxiliary semiconductor switch for discharging the electric charge of the snubber capacitor, and a second diode connected in anti-parallel to the auxiliary semiconductor switch. A third diode connected between the connection point between the primary winding and the tertiary winding and the auxiliary semiconductor switch; and a third diode connected via the third diode. Switching power supply apparatus characterized by comprising a capacitor connected in parallel to the winding. 2. The switching power supply according to claim 1, wherein a series circuit of a resonance reactor and an auxiliary semiconductor switch is used instead of the series circuit of the resonance capacitor, the resonance reactor and the auxiliary semiconductor switch. 3. The switching power supply device according to claim 1, wherein a reactor is used instead of the transformer tertiary winding. 4. The switching power supply device according to claim 1, wherein the third diode is omitted. 5. A switching power supply device comprising a primary winding and a secondary winding and a rectifier / smoothing circuit connected to a secondary winding of a transformer connected between a DC power supply, wherein the input reactor and the transformer Main switch connected in series with the primary winding of the first semiconductor switch, a first diode connected in anti-parallel to the main semiconductor switch, a snubber capacitor connected in parallel to the main semiconductor switch, and a charge of the snubber capacitor. A switching power supply device comprising: a series circuit of a resonance capacitor, a resonance reactor, and an auxiliary semiconductor switch for discharging a current; and a second diode connected in anti-parallel to the auxiliary semiconductor switch. 6. The switching power supply according to claim 1, wherein a newly provided transformer quaternary winding is used as the input reactor instead of the input reactor. 7. A switching power supply device comprising a primary winding and a secondary winding, and a rectifier / smoothing circuit connected to a secondary winding of a transformer connected between a DC power supply, wherein the input reactor comprises: A main semiconductor switch connected in series to the primary winding of the transformer, a first diode connected in anti-parallel to the main semiconductor switch, and connected in parallel to a series circuit of the primary winding of the transformer and the main semiconductor switch. And a second circuit connected in anti-parallel to the auxiliary semiconductor switch.
And a third diode connected between the connection point between the primary winding of the transformer and the main semiconductor switch and the auxiliary semiconductor switch. 8. The switching power supply according to claim 7, wherein a newly provided transformer tertiary winding is used as the input reactor instead of the input reactor. 9. The system according to claim 7, wherein the input reactor is removed, and a series circuit of the capacitor and the auxiliary switch is replaced with a series circuit of a capacitor, a transformer tertiary winding, and an auxiliary semiconductor switch. Switching power supply. 10. A series circuit in which a semiconductor switch is connected in series with a primary winding of a transformer is connected in parallel with an electrolytic capacitor and a rectifier for converting an AC voltage to a DC voltage.
A rectifying / smoothing circuit is connected between secondary windings of a transformer, and a switching power supply for supplying DC power to a load by turning on / off the semiconductor switch, wherein a transformer is provided between a connection point between the rectifier and an electrolytic capacitor. A tertiary winding and a series circuit of a diode for reverse recovery are connected. 11. A series circuit in which a first semiconductor switch is connected in series with a primary winding of a transformer is connected in parallel with an electrolytic capacitor and a rectifier for converting an AC voltage to a DC voltage. A rectifying / smoothing circuit is connected between the windings to turn on / off the first semiconductor switch to supply DC power to a load. A switching power supply device, wherein a series circuit of a diode and a series circuit of a tertiary winding of a transformer and a second semiconductor switch are connected in parallel with an electrolytic capacitor. 12. A switching power supply in which a primary winding of a transformer and a main semiconductor switch are connected in series with a DC power supply, wherein a series of a resonance inductance, a resonance capacitor, and an auxiliary semiconductor switch are connected to the main semiconductor switch. A switching power supply device, wherein circuits are connected in parallel, and when the output power including the standby mode is low, the switching power supply device is operated by turning on and off only the auxiliary semiconductor switch. 13. The switching power supply according to claim 12, wherein the resonance inductance is a tertiary winding of a transformer. 14. A switching power supply in which a primary winding of a transformer and a semiconductor switch are connected in series with a DC power supply in series with a semiconductor integrated circuit for driving and controlling the semiconductor switch. A control integrated circuit for driving and controlling the main power supply for supplying power and the semiconductor switch of the switching power supply in which a primary winding of a transformer and a semiconductor switch are also connected in series with a DC power supply are connected in series. And a sub-power supply for supplying power during standby, and integrating the semiconductor switch of the main power supply and the integrated circuit for controlling the same and the semiconductor switch of the sub-power supply and the integrated circuit for controlling the same, and storing them in the same package. A switching power supply device characterized by the above-mentioned. 15. The switching power supply according to claim 14, wherein at least one of the main power supply and the sub power supply is the switching power supply according to any one of claims 1 to 13. 16. A switching power supply device in which a primary winding of a transformer and a semiconductor switch are connected in series with a DC power supply is provided as a main power supply and a sub power supply, and a semiconductor switch of the main power supply and a semiconductor switch of the sub power supply are provided. A switching power supply device, wherein a common control integrated circuit for controlling the power supply is integrated with these semiconductor switches and housed in the same package. 17. The switching power supply according to claim 16, wherein at least one of the main power supply and the sub power supply is the switching power supply according to any one of claims 1 to 13.