JP3248198B2 - 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 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 for rectifying and smoothing an AC input voltage from an AC power supply to convert it to a DC voltage and supplying the DC voltage to an inverter or the like has been widely used. Used. FIG. 16 is a circuit diagram of a conventional power supply device (see JP-A-59-220081). In this circuit, the AC power supply Vs is connected to a full-wave rectifier DB
And an inverter A is connected to a DC output terminal of the full-wave rectifier DB, and an auxiliary power supply circuit B is connected. In the 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,
3. The capacitor C1 is charged through a path passing through the transistor Q2 and the full-wave rectifier DB. During periods of low power supply voltage,
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 is connected to the inverter A and the auxiliary power supply circuit B.
It is merely shared with. The auxiliary power circuit B
Since this 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.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to share parts between an inverter and an auxiliary power supply circuit for supplying DC power to the inverter while the power supply voltage is low. It is another object of the present invention to provide a power supply device in which the circuit configuration is further simplified by simplifying the circuit configuration and the harmonic component of the input current is reduced.

[0005]

According to the power supply device of the present invention, in order to solve the above-mentioned problems, as shown in FIG. 1, an AC power supply Vs and an AC input voltage from the AC power supply Vs are used. Full-wave rectifier DB for full-wave rectification and full-wave rectifier DB
And an inverter having a load circuit including an LC resonance system connected to the output of the inverter, a capacitor C1 for supplying DC power to the inverter, and the LC resonance system of the inverter .
That the inductor L1 and the charge diode D3 for supplying a charging current to the capacitor C1 from the output of the full-wave rectifier DB through the switching element, a discharging diode D4 for supplying DC power from the capacitor C1 to the inverter It is characterized by having.

[0006]

According to the present invention, the LC resonance system of the inverter is
The inductor L1 and the switching element are also used as components of a step-down chopper, and the capacitor C1 is charged by the step-down chopper, and DC power is supplied from the capacitor C1 to the inverter via the diode D4 to the inverter during a period when the power supply voltage is low. Therefore, the number of parts in the entire apparatus is reduced due to the effect of sharing parts, and the circuit configuration is simplified.

[0007]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.
Hereinafter, the circuit configuration of the present embodiment will be described. The AC power supply Vs is connected to an 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 anti-parallel 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 connected between the connection point of the transistors Q1 and Q2 and the connection point of the capacitors C3 and C4.
1, a parallel circuit of a load F and a capacitor C2 is connected. A capacitor C1 for power supply smoothing and 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 a current flowing through this circuit. The charging voltage of the capacitor C1 is applied to a series circuit of the transistors Q1 and Q2 via the diode D4.

Hereinafter, the operation of the present embodiment will be described.
In this embodiment, the transistors Q1 and Q2 are alternately turned on.
It turns off, operates as a half-bridge type inverter using the rectified output voltage of the full-wave rectifier DB or the charged voltage of the capacitor C1 as a power supply, and supplies high-frequency power to the load F.
That is, when the transistor Q1 turns on, the capacitor C
3, a current flows through a transistor Q1, an inductor L1, a parallel circuit of a load F and a capacitor C2, and a capacitor C3.
4. Parallel circuit of load F and capacitor C2, inductor L
1, a current flows through a path passing through the transistor Q2 and the capacitor C4, so that the load F is supplied with high-frequency power having the switching frequency of the transistors Q1 and Q2. Note that the capacitor C2 and the inductor L1 form an LC series resonance circuit, and a voltage generated at both ends of 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 for dividing the input DC voltage of the inverter, which has a sufficiently large capacity as compared with the resonance capacitor C2.

Next, the charging / discharging operation of the power supply 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 while 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 one charging path, the rush current to the capacitor C1 at the initial stage of turning on the power is reduced. When the transistor Q2 is turned off, a regenerative current flows through a path passing through the inductor L1, the diode D1, the capacitor C1, the diode D3, and the inductor L1 due to the energy stored in the inductor L1, and the capacitor C1 is charged. As described above, the inductor L1, the diodes D1 and D3, the transistor Q2, and the capacitor C1 constitute a step-down chopper, and charge the capacitor C1. The circuit configuration is simplified by using the inductor L1, the diode D1, and the transistor Q2 in the step-down chopper and the inverter. 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. I do.

FIG. 2 is a circuit diagram of a second embodiment of the present invention. In the present embodiment, the configuration of the inverter is changed from a half-bridge type to a full-bridge type in the circuit of FIG.
It is replaced with Q4. Each transistor Q3, Q
4, diodes D5 and D6 are connected in anti-parallel. In this full-bridge inverter, the transistors Q1 and Q4 turn on / off in the same phase, and the transistors Q2 and Q3 turn 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 while the power supply voltage is sufficiently high. When the transistor Q2 is turned off, a regenerative current flows through a path passing through the inductor L1, the diode D1, the capacitor C1, the diode D3, and the inductor L1 due to the energy stored in the inductor L1, and the capacitor C1 is charged. And, during the period when the power supply voltage is low,
Capacitor C1 supplies DC power to the inverter through diode D4 connected in series with capacitor C1. As described above, the operation related to charging and discharging of the capacitor C1 is exactly the same as the circuit of FIG.

FIG. 3 is a circuit diagram of a third embodiment of the present invention. This embodiment is different from the circuit shown in FIG. 1 in that the configuration of the inverter is changed from a half-bridge type to a single type. The capacitor C4 is omitted, and a capacitor C3 and an inductor L are used instead of the transistor Q1 and the diode D1.
2 LC parallel resonance circuits, and a parallel circuit of a fluorescent lamp load FL and a capacitor C2 is connected to both ends of the 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 while the power supply voltage is sufficiently high. When the transistor Q2 is turned off, the inductor L1
L1, capacitor C3, capacitor C1, diode D3, inductor L
1, a regenerative current flows through the path, and the capacitor C1 is charged. 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 to the capacitor C1. As described above, the operation related to charging and discharging of the capacitor C1 is
This is almost the same as the circuit of FIG. 1, except that the path through which the regenerative current flows is replaced by the diode D1 and the capacitor C3.

FIG. 4 is a circuit diagram of a fourth embodiment of the present invention. Hereinafter, the circuit configuration will be described. AC power supply V
s is connected to the AC input terminal of the full-wave rectifier DB.
A diode D5 is connected between the DC output terminals of the full-wave rectifier DB.
, A series circuit of the transistors Q1 and Q2 is connected. Diodes D1 and D2 are connected in anti-parallel to the transistors Q1 and Q2, respectively. A load F and a capacitor C2 are connected between the DC output terminals of the full-wave rectifier DB.
Are connected via a series circuit of capacitors C4 and C3. An inductor L1 is connected between a connection point between the transistors Q1 and Q2 and a connection point between the capacitors C3 and C4. A diode D5 and a series circuit of a power supply smoothing capacitor C1, 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 a current flowing through this circuit. Is done. The charging voltage of the capacitor C1 is applied to a series circuit of the transistors Q1 and Q2 via the diode D4. A high-frequency bypass capacitor C5 is connected in parallel to a 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 a path passing through the full-wave rectifier DB, and the capacitor C1 is charged. The charging operation of the capacitor C1 is the same as that of each of the above-described embodiments except that the charging current path includes the diode D5. In this state, when the power supply voltage is low, a pause occurs in the input current. Therefore, in the present embodiment, the capacitor C4 is connected between a part of the load circuit of the inverter and the full-wave rectifier DB to prevent a pause of the input current. The capacity of the capacitor C4 is 1
It is small enough to charge and discharge the charge with the inductor L1 in each switching. For this reason, the potential at the connection point between the capacitor C4 and the inductor L1 fluctuates in high frequency, and when the potential is low, the potential is equal to or lower than the potential of the negative output terminal of the full-wave rectifier DB. Regardless, when the transistor Q2 is turned on, an input current flows through a path passing through the full-wave rectifier DB, the capacitor C4, the inductor L1, the transistor Q2, and the full-wave rectifier DB.
Thereby, the pause of the input current can be eliminated. The diode D5 is for discharging the charge of the capacitor C4. When the transistor Q1 is turned on, the charge of the capacitor C4 is discharged to the inductor L1, and the input current can flow when the transistor Q2 is turned on next. Thus, in this embodiment, the capacitor C4 and the diode D
With the addition of 5, there is an advantage that the pause of the input current is eliminated, harmonic components of the input current are reduced, and the input power factor is further increased. In other words, the performance is remarkably improved by adding a small number of components. The capacitor C5 is provided to bypass the regenerative current of the inverter, but is not always necessary.

FIG. 5 is a circuit diagram of a fifth embodiment of the present invention. In the present embodiment, the capacitor C4 in the circuit of FIG. 4 is replaced with an inductor L2. As compared with the case where the capacitor C4 is used, the inductor L2 has a slight boosting action, and the input current flows more easily. That is, by generating a voltage in the inductor L2 in a direction superimposed on the output voltage of the full-wave rectifier DB, the input current can flow even during a period in which the power supply voltage is low.
Thereby, harmonic components of the input current can be reduced.

FIG. 6 is a circuit diagram of a sixth embodiment of the present invention. In the present embodiment, the 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 between both ends becomes oscillating. Therefore, even when the output voltage of the full-wave rectifier DB is low, the input current can flow by the voltage generated in the LC series resonance circuit,
It is possible to eliminate the pause of the input current and reduce the harmonic component of the input current.

FIG. 7 is a circuit diagram of a seventh embodiment of the present invention. In the present 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 flows more easily when the connection current is arranged at the connection location shown in FIG. 7 than at the connection location shown in FIG. 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 between the parallel circuit of the load F and the capacitor C2 and the connection point of the capacitor C3 in the circuit of FIG. 7 are replaced. In this case, the capacitor C3
Is preferably set smaller than usual so that the potential fluctuation at the point where the series circuit of the capacitor C4 and the inductor L2 is connected increases. Note that the inductor L2 can be omitted.

FIG. 9 is a circuit diagram of a ninth embodiment of the present invention. In the present embodiment, in the circuit of FIG. 6, the load circuit of the inverter connected to both ends of the transistor Q2 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. Things.
The basic operation is the same. When the transistor Q2 is turned on during a 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 through the path passing through B, and the capacitor C1 is charged. When the transistor Q2 is turned off, a current flows through a path passing through the inductor L1, the diode D1, the capacitor C1, the diode D3, and the inductor L1, and the capacitor C1 is charged. During the period when the power supply voltage is low, the charging voltage of the capacitor C1 is applied to the input of the inverter (ie, the transistors Q1, Q
2 at both ends of the series circuit. Further, a full-wave rectifier D is connected through a series circuit of a capacitor C4 and an inductor L2.
The input current flows from the output terminal of B to a part of the load circuit of the inverter (the inductor L1 in this embodiment), so that 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 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 through a series circuit of the capacitor C4 and the inductor L2. In the circuit of FIG.
, An input current flows through a series circuit of the capacitor C3 and the inductor L1. Here, the 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 an eleventh embodiment of the present invention. In the present embodiment, the connection point of 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, an input current flows through the series circuit of the capacitor C3 and the inductor L1 via the impedance element Z, but in the circuit of FIG. The input current flows through a 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 a 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 while the power supply voltage is high, the full-wave rectifier DB, the inductor L2, the capacitor C1,
3, inductor L1, transistor Q2, full-wave rectifier D
The input current flows through the path passing through B, and the capacitor C1 is charged. When the transistor Q2 is turned off, a current flows through a path passing 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. During the period when 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, and the capacitor C
3. Parallel circuit of load F and capacitor C2, inductor L
1, transistor Q2, diode D4, capacitor C
The current flows in a path passing through No. 1. At this time, the inductor L
2, a voltage is generated rightward in the figure, so that 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. An input current flows through a path passing through the full-wave rectifier DB. Therefore, the inductor L2 not only functions as a component of the step-down chopper, but also has an action of reducing harmonic components 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 point of the capacitor C1 is changed, and the inductor L2 is connected to the output terminal of the full-wave rectifier DB. FIG.
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 a switching element of the step-down chopper.

FIG. 14 is a circuit diagram of a fourteenth embodiment of the present invention. In this embodiment, in the circuit of FIG. 1 state, and are not inserted parallel circuit of the impedance element Z and the diode D5 between the capacitor C3 and the transistor Q1, wherein
That corresponds to the invention of claim 3. During periods when power supply voltage is low
When the transistor Q2 is turned on, the capacitor C1,
A current flows through a path passing through 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. At this time, a voltage is generated in the impedance element Z in the rightward direction in the figure. Therefore, 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 load F and the capacitor An input current flows through a path passing through the parallel circuit of C2, the inductor L1, the transistor Q2, and the full-wave rectifier DB. Therefore,
The impedance element Z has a function of reducing harmonic components of the input current.

FIG. 15 is a circuit diagram of a fifteenth embodiment of the present invention. In this 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 components of the step-down chopper for charging the capacitor C1 during the period when the power supply voltage is high, and has the function of reducing the harmonic component of the input current by flowing the input current during the period when the power supply voltage is low. is there. That is, when the transistor Q1 is turned on, current flows through a path passing 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 rightward direction in the drawing. 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 and the transistor Q
1, an input current flows through a path passing through the inductor L1, the parallel circuit of the load F and the capacitor C2, the capacitor C4, and the full-wave rectifier DB. Therefore, the pause of the input current does not occur even when the power supply voltage is low. Thereby, 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. For example, a fluorescent lamp load or an incandescent lamp load may be used. 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 first aspect of the present invention, in a power supply device including a full-wave rectifier for full-wave rectifying an AC power supply and an inverter driven by an output of the full-wave rectifier, an LC resonance system of the inverter is provided. Constituent inductors and switches
The switching element is also used as a component of the step-down chopper, and the capacitor is charged by the step-down chopper, and DC power is supplied from the capacitor to the inverter during a period when the power supply voltage is low. The parts can be shared, and the number of parts is reduced, thereby reducing the apparatus cost and simplifying the circuit configuration.

Further, 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 present invention, the input current can be prevented from stopping and the input current can be reduced. There is an effect that the higher harmonic component can be reduced. Further, according to the third aspect of the present invention,
Thus, the output of the full-wave rectifier and the first and second switching
A first diode and an impedance between the
If a parallel circuit of dance elements is inserted, the output of the full-wave rectifier
Input current even if the voltage is lower than the voltage of the first capacitor
To reduce harmonic components of the input current.
Can be.

[Brief description of the 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 (3)

(57) [Claims] An AC power supply, a full-wave rectifier for full-wave rectifying an AC input voltage from the AC power supply, an inverter having a load circuit connected to an output of the full-wave rectifier and including an LC resonance system, A capacitor for supplying power, a charging diode for flowing a charging current from the output of the full-wave rectifier to the capacitor via an inductor and a switching element constituting the LC resonance system of the inverter, A power supply device comprising: a discharge diode for supplying DC power from the capacitor to an inverter. 2. The power supply device according to claim 1, further comprising an impedance element for connecting a part of a load circuit of the inverter to an output of the full-wave rectifier. 3. An AC power supply, a full-wave rectifier for full-wave rectifying an AC input voltage from the AC power supply, and an output of the full-wave rectifier connected to the output of the full-wave rectifier via a first diode to be turned on and off alternately.
A series circuit of the first and second switching elements to be turned off, an impedance element connected in parallel to the first diode, and a series circuit of the first and second switching elements in parallel with the second diode via the second diode. , A series circuit of second and third capacitors connected in parallel to the output of the full-wave rectifier, and one end connected to a connection point of the first and second switching elements. An inductor, a load connected between the connection point of the second and third capacitors and the other end of the inductor,
A fourth capacitor connected in parallel to the load so as to form an LC series resonance circuit; and a third capacitor connected between a connection point between the first capacitor and the second diode and the other end of the inductor. And the first and third diodes.
Is connected in such a direction that the first capacitor can be charged from the output of the rectifier through the inductor when one of the switching elements is turned on, and the second diode can discharge the first capacitor when the other switching element is turned on. A power supply device connected in a direction.