JPH0556647A - Power supply - Google Patents

Abstract

PURPOSE:To simplify circuitry by promoting the double use of parts for an auxiliary power circuit to give DC power to an inverter for the period of low supply voltage and the inverter. CONSTITUTION:A power device is constituted in such a manner that the inductor L1 of an inverter and a switching element are also used as the components for a step-down chopper, a capacitor C1 is charged by the step-down chopper and DC power is given to the inverter for the period of low supply voltage through a diode D4 from the capacitor C1. Accordingly, the number of parts as the whole device is decreased by the shared effect of the parts, thus simplifying circuitry.

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 converting an AC input voltage from an AC power supply into a DC voltage, converting the DC voltage into a high frequency by an inverter, and supplying the high frequency to a load.

[0002]

2. Description of the Related Art Conventionally, in order to drive a high frequency lighting device for a fluorescent lamp, a power supply device has been widely used which rectifies and smoothes an AC input voltage from an AC power supply to convert it into a DC voltage and supplies the DC voltage to an inverter or the like. It is used. FIG. 16 is a circuit diagram of a conventional power supply device (see Japanese Patent Laid-Open No. 59-220081). In this circuit, the AC power supply Vs is connected to the full-wave rectifier DB
Of the full-wave rectifier DB, the inverter A, and the auxiliary power supply circuit B. In this auxiliary power supply circuit B, when the transistor Q2 is turned on while the power supply voltage is high, the full-wave rectifier DB, the capacitor C1, the inductor L2, the diode D
3, the capacitor C1 is charged in a path passing through the transistor Q2 and the full-wave rectifier DB. During periods when the power supply voltage is low,
The capacitor C1 of the auxiliary power supply circuit B serves as the power supply of the inverter A.

[0003]

In the above-mentioned conventional example, the inverter A and the auxiliary power supply circuit B are separated, and only the transistor Q2 has the inverter A and the auxiliary power supply circuit B.
It is only used for and. In addition, auxiliary power circuit B
Since it is a step-down chopper, there is a problem in that a pause occurs in the input current, a harmonic component of the input current increases, and this causes a malfunction of other electric devices connected to the same system.

The present invention has been made in view of the above circumstances, and an object of the present invention is to use both an auxiliary power supply circuit for supplying DC power to an inverter and a component as a component while the power supply voltage is low. A further object of the present invention is to provide a power supply device in which the circuit configuration is further promoted to simplify the circuit configuration and the harmonic components of the input current are reduced.

[0005]

In order to solve the above-mentioned problems, the power supply device of the present invention provides an AC power supply Vs and an AC input voltage from the AC power supply Vs as shown in FIG. Full-wave rectifier DB for full-wave rectification and full-wave rectifier DB
Of the full-wave rectifier DB via an inverter connected to the output of the load circuit including a load circuit including an LC resonance system, a capacitor C1 for supplying DC power to the inverter, and an inductor L1 of the inverter and a switching element. Charging diode D for supplying charging current to the
3 and a discharging diode D4 for supplying DC power from the capacitor C1 to the inverter.

[0006]

In the present invention, the inductor L of the inverter is used.
1 and the switching element are also used as the constituent elements of the step-down chopper, the step-down chopper charges the capacitor C1, and the DC power is supplied from the capacitor C1 to the inverter via the diode D4 during the period when the power supply voltage is low. As a result of the shared use of parts, the number of parts in the device as a whole is reduced, and the circuit configuration is simplified.

[0007]

1 is a circuit diagram of a first embodiment of the present invention.
The circuit configuration of this embodiment will be described below. The AC power supply Vs is connected to the AC input terminal of the full-wave rectifier DB. A series circuit of transistors Q1 and Q2 is connected between the DC output terminals of the full-wave rectifier DB. Diodes D1 and D2 are connected in antiparallel to the transistors Q1 and Q2, respectively. A series circuit of capacitors C3 and C4 is connected in parallel between the DC output terminals of the full-wave rectifier DB. An inductor L is provided between the connection point of the transistors Q1 and Q2 and the connection point of the capacitors C3 and C4.
A parallel circuit of the load F and the capacitor C2 is connected via 1. A capacitor C1 for smoothing the power supply, a series circuit of a diode D3, an inductor L1, and a transistor Q2 are connected between the DC output terminals of the full-wave rectifier DB, and the capacitor C1 is charged by the current flowing in this circuit. The charging voltage of the capacitor C1 is applied to the series circuit of the transistors Q1 and Q2 via the diode D4.

The operation of this embodiment will be described below.
In this embodiment, the transistors Q1 and Q2 are turned on alternately.
It is turned off and operates as a half-bridge type inverter by using the rectified output voltage of the full-wave rectifier DB or the charging voltage of the capacitor C1 as a power source, and supplies the load F with high-frequency power.
That is, when the transistor Q1 turns on, the capacitor C
3, the transistor Q1, the inductor L1, the parallel circuit of the load F and the capacitor C2, the current flows through the capacitor C3, and when the transistor Q2 is turned on, the capacitor C
4, parallel circuit of load F and capacitor C2, inductor L
Since a current flows in a path that passes through the transistor 1, the transistor Q2, and the capacitor C4, the load F is supplied with high-frequency power having the switching frequency of the transistors Q1 and Q2. The capacitor C2 and the inductor L1 form an LC series resonance circuit, and the voltage generated across the capacitor C2 by the resonance action is applied to the load F. Therefore, the voltage applied to the load F can be controlled by controlling the switching frequency. Each capacitor C3, C
Reference numeral 4 denotes a power supply capacitor that divides the input DC voltage of the inverter, and has a capacity set sufficiently larger than that of the resonance capacitor C2.

Next, the charging / discharging operation of the power source smoothing capacitor C1 will be described. The capacitor C1 is charged by the rectified output of the full-wave rectifier DB via the diode D3 and the inductor L1 when the transistor Q2 is turned on during the period when the power supply voltage is sufficiently high. Capacitor C
Since the inductor L1, which is a component of the inverter, is interposed in series in the charging path of No. 1, the rush current to the capacitor C1 at the initial stage of power-on becomes small. When the transistor Q2 is turned off, the stored energy of the inductor L1 causes a regenerative current to flow in a path that passes through the inductor L1, the diode D1, the capacitor C1, the diode D3, and the inductor L1 to charge the capacitor C1. In this way, the inductor L1, the diodes D1 and D3, the transistor Q2, and the capacitor C1 form a step-down chopper, and the capacitor C1 is charged. The inductor L1, the diode D1, and the transistor Q2 are shared by the step-down chopper and the inverter, so that the circuit configuration is simplified. Next, during a period when the power supply voltage is low, the capacitor C1 is connected to the input of the inverter (that is, both ends of the series circuit of the transistors Q1 and Q2) by the diode D4 connected in series to the capacitor C1 and supplies DC power to the inverter. To do.

FIG. 2 is a circuit diagram of a second embodiment of the present invention. In this embodiment, in the circuit of FIG. 1, the configuration of the inverter is changed from the half bridge type to the full bridge type, and the capacitors C3 and C4 are replaced by the transistor Q3.
It is replaced with Q4. Each transistor Q3, Q
Diodes D5 and D6 are connected in anti-parallel to 4, respectively. In this full-bridge type inverter, the transistors Q1 and Q4 are turned on / off in the same phase, and the transistors Q2 and Q3 are turned on / off in the opposite phase to supply high frequency power to the load circuit of the inverter. ..
The capacitor C1 is charged by the rectified output of the full-wave rectifier DB via the diode D3 and the inductor L1 when the transistor Q2 is turned on during the period when the power supply voltage is sufficiently high. When the transistor Q2 is turned off, the stored energy of the inductor L1 causes a regenerative current to flow in a path that passes through the inductor L1, the diode D1, the capacitor C1, the diode D3, and the inductor L1 to charge the capacitor C1. And in the period when the power supply voltage is low,
Due to the diode D4 connected in series with the capacitor C1, the capacitor C1 supplies DC power to the inverter. As described above, the operations relating to the charging and discharging of the capacitor C1 are exactly the same as those of the circuit of FIG.

FIG. 3 is a circuit diagram of a third embodiment of the present invention. In this embodiment, the configuration of the inverter is changed from the half-bridge type to the one-stone type in the circuit of FIG. 1, the capacitor C4 is omitted, and instead of the transistor Q1 and the diode D1, a capacitor C3 and an inductor L are provided.
Two LC parallel resonance circuits are connected, and a parallel circuit of a fluorescent lamp load FL and a capacitor C2 is connected to both ends of this LC parallel resonance circuit via an inductor L1. The capacitor C1 is charged by the rectified output of the full-wave rectifier DB via the diode D3 and the inductor L1 when the transistor Q2 is turned on during the period when the power supply voltage is sufficiently high. When the transistor Q2 turns off, the inductor L1
Inductor L1, capacitor C3, capacitor C1, diode D3, inductor L
A regenerative current flows through the path passing through 1 to charge the capacitor C1. Then, during a period when the power supply voltage is low, the capacitor C1 supplies DC power to the inverter by the diode D4 connected in series with the capacitor C1. In this way, the operations related to the charging and discharging of the capacitor C1 are
The circuit is almost the same as that of FIG. 1, except that the path through which the regenerative current flows is replaced with the diode D1 and the capacitor C3.

FIG. 4 is a circuit diagram of a fourth embodiment of the present invention. The circuit configuration will be described below. AC power supply V
s is connected to the AC input terminal of the full-wave rectifier DB.
A diode D5 is placed between the DC output terminals of the full-wave rectifier DB.
A series circuit of transistors Q1 and Q2 is connected via. Diodes D1 and D2 are connected in antiparallel to the transistors Q1 and Q2, respectively. A load F and a capacitor C2 are placed between the DC output terminals of the full-wave rectifier DB.
Parallel circuit is connected via a series circuit of capacitors C4 and C3. An inductor L1 is connected between the connection point of the transistors Q1 and Q2 and the connection point of the capacitors C3 and C4. A diode D5, a capacitor C1 for smoothing the power source, a diode D3, an inductor L1, and a series circuit of a transistor Q2 are connected between the DC output terminals of the full-wave rectifier DB, and the capacitor C1 is charged by the current flowing in this circuit. To be done. The charging voltage of the capacitor C1 is applied to the series circuit of the transistors Q1 and Q2 via the diode D4. A high frequency bypass capacitor C5 is connected in parallel to the series circuit of the transistors Q1 and Q2.

The operation of this embodiment will be described below.
When the transistor Q2 is turned on while the power supply voltage is high, the full-wave rectifier DB, the diode D5, and the capacitor C
1, diode D3, inductor L1, transistor Q
2. A current flows through the path passing through the full-wave rectifier DB to charge the capacitor C1. The charging operation of the capacitor C1 is the same as that in each of the above-described embodiments except that the diode D5 is included in the charging current path. In this state, when the power supply voltage is low, a pause occurs in the input current. Therefore, in this embodiment, the capacitor C4 is connected between a part of the load circuit of the inverter and the full-wave rectifier DB to prevent the interruption of the input current. The capacity of this capacitor C4 is 1
It is small enough to charge and discharge electric charge with the inductor L1 by switching once. Therefore, the potential at the connection point between the capacitor C4 and the inductor L1 fluctuates in a high frequency, and when the potential is low, the potential is the same as or lower than the negative output terminal of the full-wave rectifier DB, so that the value of the power supply voltage becomes Regardless, when the transistor Q2 is turned on, the input current flows in a path that passes through the full-wave rectifier DB, the capacitor C4, the inductor L1, the transistor Q2, and the full-wave rectifier DB.
This makes it possible to eliminate the pause of the input current. The diode D5 is for discharging the electric charge of the capacitor C4. When the transistor Q1 is turned on, the diode D5 releases the electric charge of the capacitor C4 to the inductor L1 and allows the input current to flow when the transistor Q2 is turned on next time. Thus, in this embodiment, the capacitor C4 and the diode D are
The addition of 5 has the advantages that the pause of the input current is eliminated, the harmonic components of the input current are reduced, and the input power factor is further increased. That is, the performance is remarkably improved by adding a few parts. The capacitor C5 is provided to bypass the regenerative current of the inverter, but it is not always necessary.

FIG. 5 is a circuit diagram of a fifth embodiment of the present invention. In this embodiment, the capacitor C4 in the circuit of FIG. 4 is replaced with the inductor L2. Compared to the case where the capacitor C4 is used, the inductor L2 has a slight boosting action, and the input current becomes easier to flow. That is, the voltage is generated in the inductor L2 in the direction in which it is superimposed on the output voltage of the full-wave rectifier DB, so that the input current can flow even when the power supply voltage is low.
Thereby, the harmonic component of the input current can be reduced.

FIG. 6 is a circuit diagram of a sixth embodiment of the present invention. In this embodiment, an inductor L2 is inserted in series with the capacitor C4 of the circuit of FIG. Since the capacitor C4 and the inductor L2 form an LC series resonance circuit, the voltage across them becomes oscillatory. Therefore, even when the output voltage of the full-wave rectifier DB is low, the input current can flow due to the voltage generated in the LC series resonance circuit.
It is possible to reduce the harmonic component of the input current by eliminating the pause of the input current.

FIG. 7 is a circuit diagram of a seventh embodiment of the present invention. In this embodiment, the capacitor C3 in the circuit of FIG.
Is changed from the load F side to the inductor L1 side. Since this capacitor C3 is a coupling capacitor for cutting the DC component of the inverter, it has a predetermined DC voltage. Therefore, the input current can flow more easily in the connection portion shown in FIG. 7 than in the connection portion shown in FIG. In addition, in the circuit of FIG. 7, the inductor L2 may be omitted.

FIG. 8 is a circuit diagram of an eighth embodiment of the present invention. In the present embodiment, the connection circuit of the capacitor C3 and the parallel circuit of the load F and the capacitor C2 in the circuit of FIG. 7 is replaced. In this case, the capacitor C3
It is preferable that the capacitance of is set to be smaller than usual so that the potential fluctuation at the location where the series circuit of the capacitor C4 and the inductor L2 is connected becomes large. The inductor L2 can be omitted.

FIG. 9 is a circuit diagram of a ninth embodiment of the present invention. In this embodiment, the load circuit of the inverter connected to both ends of the transistor Q2 in the circuit of FIG. 6 is connected to both ends of the transistor Q1. That is,
In the circuit of FIG. 6, the parallel circuit of the load F and the capacitor C2 and the series circuit of the capacitor C3 are connected to both ends of the transistor Q2 via the inductor L1, but in the circuit of FIG. 9, they are connected to both ends of the transistor Q1. It is a thing.
The basic operation is the same, and when the transistor Q2 is turned on during the period when the power supply voltage is high, the full-wave rectifier D
B, diode D5, capacitor C1, diode D
3, inductor L1, transistor Q2, full-wave rectifier D
The input current flows along the path passing through B, and the capacitor C1 is charged. Further, when the transistor Q2 is turned off, a current flows in a path that passes through the inductor L1, the diode D1, the capacitor C1, the diode D3, and the inductor L1, and the capacitor C1 is charged. While the power supply voltage is low, the charging voltage of the capacitor C1 is input to the inverter (that is, the transistors Q1 and Q1) via the diode D4.
2 at both ends of the series circuit). In addition, the full-wave rectifier D is connected via the series circuit of the capacitor C4 and the inductor L2.
The input current flows from the output terminal of B to a part of the load circuit of the inverter (inductor L1 in this embodiment), the pause of the input current is eliminated, and the harmonic component of the input current is reduced.

FIG. 10 is a circuit diagram of a tenth embodiment of the present invention. In the present embodiment, the connection point of the impedance element Z is changed in the circuit of FIG. That is,
In the circuit of FIG. 9, when the transistor Q2 is turned on,
An input current flows from the output terminal of the full-wave rectifier DB to the inductor L1 via the series circuit of the capacitor C4 and the inductor L2, but in the circuit of FIG.
An input current flows through the series circuit of the capacitor C3 and the inductor L1 via the. Where impedance element Z
May be a capacitor, an inductor, a series circuit of both, or a parallel circuit of both.

FIG. 11 is a circuit diagram of the eleventh embodiment of the present invention. In the present embodiment, the parallel circuit of the load F and the capacitor C2 and the connection point of the capacitor C3 are replaced in the circuit of FIG. That is, in the circuit of FIG. 10, when the transistor Q2 is turned on, the input current flows through the impedance element Z to the series circuit of the capacitor C3 and the inductor L1, but in the circuit of FIG. 11, the load F and the capacitor C2 are connected. The input current flows in the series circuit of the parallel circuit and the inductor L1. In this case,
It is preferable to set the capacitance of the capacitor C3 to be slightly smaller and to increase the potential fluctuation at one end of the capacitor C3.

FIG. 12 is a circuit diagram of the twelfth embodiment of the present invention. In this embodiment, an inductor L2 is added to the components of the step-down chopper for charging the capacitor C1 in the circuit of FIG. When the transistor Q2 is turned on during the period when the power supply voltage is high, the full-wave rectifier DB, the inductor L2, the capacitor C1, the diode D
3, inductor L1, transistor Q2, full-wave rectifier D
The input current flows along the path passing through B, and the capacitor C1 is charged. Further, when the transistor Q2 is turned off, a current flows in a path that passes through the inductor L1, the diode D1, the inductor L2, the capacitor C1, the diode D3, and the inductor L1, and the capacitor C1 is charged. While the power supply voltage is low, the charging voltage of the capacitor C1 is supplied to the input of the inverter via the diode D4 and the inductor L2. That is, when the transistor Q2 is turned on, the capacitor C1, the inductor L2, the capacitor C
3, parallel circuit of load F and capacitor C2, inductor L
1, transistor Q2, diode D4, capacitor C
An electric current flows through the path passing through 1. At this time, inductor L
2, a voltage is generated rightward in the figure, so even if the output voltage of the full-wave rectifier DB is lower than the voltage of the capacitor C1, the full-wave rectifier DB, the capacitor C3, the parallel circuit of the load F and the capacitor C2, Inductor L1, transistor Q
2. The input current flows along the path passing through the full-wave rectifier DB. Therefore, the inductor L2 not only serves as a constituent element of the step-down chopper but also has an action of reducing the harmonic component of the input current.

FIG. 13 is a circuit diagram of a thirteenth embodiment of the present invention. In the present embodiment, in the circuit of FIG. 12, the connection location of the capacitor C1 is changed and the inductor L2 is connected to the output terminal of the full-wave rectifier DB. Figure 1
In the circuit of No. 2, the transistor Q2 of the inverter is shared as the switching element of the step-down chopper,
In the circuit of FIG. 13, the transistor Q1 of the inverter is shared as the switching element of the step-down chopper.

FIG. 14 is a circuit diagram of a fourteenth embodiment of the present invention. In this embodiment, a parallel circuit of an impedance element Z and a diode D5 is inserted between the capacitor C3 and the transistor Q1 in the circuit of FIG. When the transistor Q2 is turned on during the period when the power supply voltage is low, a current flows through the capacitor C1, the impedance element Z, the capacitor C3, the parallel circuit of the load F and the capacitor C2, the inductor L1, the transistor Q2, the diode D4, and the capacitor C1. Flows. At this time, since a voltage is generated in the impedance element Z in the rightward direction in the figure, even if the output voltage of the full-wave rectifier DB is lower than the voltage of the capacitor C1, the full-wave rectifier DB, the capacitor C3,
Parallel circuit of load F and capacitor C2, inductor L1,
The input current flows through the path passing through the transistor Q2 and the full-wave rectifier DB. Therefore, the impedance element Z has a function of reducing the harmonic component of the input current.

FIG. 15 is a circuit diagram of the fifteenth embodiment of the present invention. In the present embodiment, in the circuit of FIG. 14, the arrangement of the transistors Q1 and Q2 and the capacitors C3 and C4 is exchanged, and the inductor L2 is connected between the transistor Q1 and the capacitor C3. Inductor L2
Is included in the constituent elements of the step-down chopper for charging the capacitor C1 during the period when the power supply voltage is high, and also has the action of allowing the input current to flow during the period when the power supply voltage is low and reducing the harmonic components of the input current. is there. That is, when the transistor Q1 is turned on, current flows through a path that passes through the capacitor C1, the inductor L2, the transistor Q1, the inductor L1, the parallel circuit of the load F and the capacitor C2, the capacitor C4, the diode D4, and the capacitor C1.
At this time, a voltage is generated in the inductor L2 in the right direction in the figure, and even if the output voltage of the full-wave rectifier DB is lower than the voltage of the capacitor C1, the full-wave rectifier DB, the transistor Q
1, an input current flows through a path passing through the inductor 1, the parallel circuit of the load F and the capacitor C2, the capacitor C4, and the full-wave rectifier DB. Therefore, the input current does not stop even during the period when the power supply voltage is low. As a result, the harmonic component of the input current is reduced.

In the power supply device of the present invention, the load F is not particularly limited, but it is possible to use, for example, a fluorescent lamp load or an incandescent lamp load. Further, a low-pass filter circuit for removing high frequency noise may be interposed between the AC power supply Vs and the full-wave rectifier DB.

[0026]

According to the invention described in claim 1, in a power supply device comprising a full-wave rectifier for full-wave rectifying an AC power supply and an inverter driven by the output of the full-wave rectifier, a switching element and an inductor of the inverter are provided. Is also used as a component of the step-down chopper, the step-down chopper charges the capacitor, and DC power is supplied from the capacitor to the inverter while the power supply voltage is low. Since it can be shared, the device cost can be reduced by reducing the number of parts, and the circuit configuration can be simplified.

If an impedance element for connecting a part of the load circuit of the inverter to the output of the full-wave rectifier is provided as in the second aspect of the invention, the input current can be eliminated and the input current can be eliminated. There is an effect that the harmonic component of can be reduced.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram of a second embodiment of the present invention.

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

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

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

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

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

FIG. 8 is a circuit diagram of an eighth embodiment of the present invention.

FIG. 9 is a circuit diagram of a ninth embodiment of the present invention.

FIG. 10 is a circuit diagram of a tenth embodiment of the present invention.

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

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

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

FIG. 14 is a circuit diagram of a fourteenth embodiment of the present invention.

FIG. 15 is a circuit diagram of a fifteenth embodiment of the present invention.

FIG. 16 is a circuit diagram of a conventional example.

[Explanation of symbols]

 Vs AC power supply DB Full-wave rectifier Q1 transistor Q2 transistor L1 inductor F load D1, ..., D5 diode C1, ..., C4 capacitor

Claims (2)

[Claims] 1. An AC power supply, a full-wave rectifier for full-wave rectifying an AC input voltage from the AC power supply, an inverter including a load circuit connected to the output of the full-wave rectifier and including an LC resonance system, and a DC power supply for the inverter. A capacitor for supplying electric power, a charging diode for causing a charging current to flow from the output of the full-wave rectifier to the capacitor through the inductor and the switching element of the inverter, and for supplying DC power from the capacitor to the inverter. A power supply device comprising a discharging diode. 2. The power supply device according to claim 1, further comprising an impedance element for connecting a part of the load circuit of the inverter to the output of the full-wave rectifier.