JP2000134941A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the startability of an HID lamp and keep power characteristics and power output constant even if the voltage of the lamp becomes higher than usual. SOLUTION: This power supply equipment is provided with switching elements S1-S4, diodes D1-D6, inductors L1, L2, and a smoothing capacitor C1. This equipment is also installed with a control circuit 11. When the right side of a switching element S7 and of an AC power supply AC becomes negative, the control circuit 11 repeatedly conducts a series of control in which it turns only the switching elements S2, S3 on and then turns only the switching element S7 on and finally turns all the switching elements off. When the right side becomes positive, it repeatedly conducts a series of control in which it turns only the switching elements S1, S4 on and then turns only the switching element S7 on and finally turns all the switching elements off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply circuit for obtaining DC power by taking power from an AC power supply, and an inverter circuit for supplying AC power to a load circuit using the power from the DC power supply circuit. The present invention relates to a power supply device configured.

[0002]

2. Description of the Related Art Conventionally, for a load circuit composed of, for example, a discharge lamp or the like, a DC power supply circuit that takes in power from an AC power supply and obtains DC power, and an AC power supply to the load circuit using power from the DC power supply circuit. 2. Description of the Related Art A power supply device including an inverter circuit for supplying electric power is widely used. As such a power supply device, there is known a DC power supply circuit and an inverter circuit which also serve as switching elements.

FIG. 9 is a schematic configuration diagram of a power supply apparatus employing a so-called dual-purpose chopper system described in Japanese Patent Application No. 9-234811.

[0004] This power supply device comprises a series-connected FET Q1,
Q2, series-connected FETs Q3 and Q4 connected in parallel with the FETs Q1 and Q2, series-connected FETs Q5 and Q6 connected in parallel with the FETs Q1 and Q2,
One end is connected in series with an AC power supply AC between the connection point of Q2 and the connection point of FETs Q5 and Q6.
The inductor L1 connected to the connection point of
A smoothing capacitor C1 connected in parallel with Q4 and an FET Q
An inductor L2 connected in series together with a load circuit LD between the connection point of the FETs Q1 and Q2 and the connection point of the FETs Q3 and Q4.
1 and Q2.

When the output terminal on the connection point side of the FETs Q1 and Q2 of the two output terminals of the AC power supply AC has a negative polarity (from the output terminal on the connection point side of the FETs Q5 and Q6, the power supply device enters the power supply device). FET Q)
2, Q3 and Q6 are turned on, only the FET Q3 is turned on, and then the FETs Q1 to Q6 are repeatedly turned on / off. On the other hand, when the output terminal on the connection point side of the FETs Q1 and Q2 becomes positive (FETQ1 , Q2, the current can be drawn into the power supply from the output end on the connection point side), and only the FETs Q1, Q4, Q5 are turned on,
Next, only the FETs Q2 and Q4 are turned on.
An unillustrated control circuit for repeatedly performing on / off control for turning off Q1 to Q6 is provided.

When the on / off control is performed by this control circuit, when the output terminal on the connection point side of the FETs Q1 and Q2 is negative, while only the FETs Q2, Q3 and Q6 are on, Opposite currents flow through the FET Q2 from the AC power supply AC and the smoothing capacitor C1, and during a period in which only the FET Q3 is on, opposing currents flow through the AC power supply AC and the inductor L.
It will flow from 2.

On the other hand, when the output terminal on the connection point side of the FETs Q1, Q2 is positive, the FETs Q1, Q4,
During the period in which only Q5 is on, currents in opposite directions flow through the FET Q1 from the AC power supply AC and the smoothing capacitor C1, and in the period in which only the FETs Q2 and Q4 are on, they are in opposite directions. Current is AC power A
It will flow from C and inductor L2.

As described above, the commonly used FETs Q1 and Q2
Of each of the FETs Q1 and Q2
, The loss is reduced.

However, each of the FETs Q1 to Q6 has a structure having a body (parasitic) diode (shown by a broken line in FIG. 9) to which a source / substrate is connected and a cathode and an anode are connected to a drain and a source, respectively. ing.

Further, since the FETs Q1 and Q2 are used in common, the DC power supply circuit has FETs Q1, Q2, Q5, Q6,
The inverter circuit is constituted by an inductor L1 and a smoothing capacitor C1, and the inverter circuit is constituted by FETs Q1 to Q4 and an inductor L2.

[0011]

However, in the power supply device shown in FIG. 9, the load circuit LD is composed of the HID lamp La and the capacitor C2 connected in parallel with the HID lamp La, as in FIG. 10 described later. Then, there arises a problem that it is difficult to secure the lamp voltage at the time of starting.

That is, when the HID lamp La is in a high impedance state until the start of discharge, the capacitor C2
Is rapidly charged to almost the voltage across the smoothing capacitor C1 by the smoothing capacitor C1 when the FETs Q2 and Q3 or the FETs Q1 and Q4 are turned on. In this case, since the voltage across the capacitor C2 is almost the same as the voltage across the smoothing capacitor C1 and the lamp voltage is high, it can be said that this is a desirable state for the HID lamp La at the start. However, after this, the capacitor C2 is connected to the FET Q1,
Q3 or FETs Q2 and Q4 turn on, inductor L
2, the capacitor C2 discharges,
The energy moves to the inductor L2. And
Finally, the energy of the inductor L2 returns to the smoothing capacitor C1 and returns. As a result, the voltage between both ends of the capacitor C2 becomes lower than the voltage between both ends of the smoothing capacitor C1, and the lamp voltage decreases, so that the above-described problem occurs.

FIG. 10 is a schematic configuration diagram of a power supply device disclosed in Japanese Patent Application No. 10-79921 which can solve such a problem.

As described in "Means for Solving the Problems" in this specification, this power supply device includes switching elements S1 and S2 connected in series, and switching elements S1 and S2 connected in parallel with these switching elements S1 and S2. The switching elements S3 and S4 connected in series and the FETs Q1 to Q4 shown in FIG.
Diode D1 connected in parallel with switching elements S1 to S4 in the same circuit arrangement as the respective parasitic diodes of
To D4, series-connected diodes D5 and D6 connected in parallel with switching elements S1 and S2, and an AC power supply AC connected in series between a connection point between switching elements S1 and S2 and a connection point between diodes D5 and D6. Inductor L1 having one end connected to a connection point between diodes D5 and D6
And a smoothing capacitor C1 connected in parallel with the switching elements S3 and S4, and a control circuit outside the figure.

This control circuit corresponds to the first embodiment in the above specification.
In the case where the HID lamp La is in a high impedance state before the start of discharge, of the two output terminals of the AC power supply AC,
When the output terminal on the connection point side of the switching elements S1 and S2 becomes negative, on / off control for turning on only the switching elements S2 and S3 and then turning off the switching elements S1 to S4 is repeated. And ON / OFF control for turning ON only the switching elements S2 and S3, then turning ON only the switching elements S1 and S3, and then turning OFF the switching elements S1 to S4. Thus, the switching element S
When the ON operation of the switching element S1 is temporarily stopped for a certain period of time from the time when the output terminal on the connection point side of 1, 1 and S2 becomes negative, the capacitor C2 is not short-circuited via the inductor L2. For a certain period of time, a voltage substantially equal to the voltage across the smoothing capacitor C1 is maintained.

On the other hand, when the output terminal on the connection point side of the switching elements S1 and S2 among the two output terminals of the AC power supply AC has a positive polarity, only the switching elements S1 and S4 are turned on.
Next, turn on / off the switching elements S1 to S4.
The off control is repeatedly performed, and after a lapse of a certain time, the on / off control for turning on only the switching elements S1 and S4, then turning on only the switching elements S2 and S4, and then turning off the switching elements S1 to S4 is repeated. Done. Thus, the switching elements S1, S2
For a certain period of time from the time when the output terminal on the connection point side of
When the ON operation of the switching element S2 is temporarily stopped, the capacitor C2 is not short-circuited via the inductor L2, so that the capacitor C2 maintains substantially the same voltage as the voltage across the smoothing capacitor C1 for a certain period of time. However, the voltage polarity is opposite to the above case.

As described above, the on / off control of the control circuit improves the startability of the HID lamp.

However, in the power supply device shown in FIG. 10, when the voltage across the smoothing capacitor C1 further decreases, the switching elements S1 and S3 or the switching elements S2 and S4 are turned on to maintain the constant power characteristic. It is necessary to make the period longer, but if the period is made longer, the amount of power supplied to the load circuit LD will be further reduced, and it will be difficult to maintain a constant power output.

For example, in the case of an HID lamp, the lamp voltage may be higher than usual due to the end of life or the dispersion of solids. In such a case, when the load circuit LD is short-circuited via the inductor L2 during normal lighting, the load circuit L
The amount of power supplied to D decreases. At this time, HID
Since the lamp is lit and consuming power, HI
A larger amount of power is required than when the D lamp is in a high impedance state before the start of discharge, and as a result, the switching elements S1, S3 or S2, S3
4 is turned on for a longer period. However, if the period is lengthened, a vicious cycle occurs in which the amount of power supplied to the load circuit LD decreases, and it becomes difficult to stably turn on the HID lamp whose lamp voltage is higher than usual.

The present invention has been made in view of the above circumstances. For example, even if a load circuit is constituted by an HID lamp and a capacitor connected in parallel with the HID lamp, the startability of the HID lamp can be improved. It is an object of the present invention to provide a power supply device capable of maintaining a constant power characteristic and a constant power output even when the lamp voltage of the HID lamp becomes higher than usual.

[0021]

According to a first aspect of the present invention, there is provided a power supply apparatus comprising: first and second switching elements connected in series; and a serial connection connected in parallel with the first and second switching elements. Third and fourth switching elements, first to fourth diodes respectively connected in parallel with the first to fourth switching elements, and fifth and fifth series-connected diodes connected in parallel to the first and second switching elements. And a sixth diode, a first inductor connected in series with an AC power supply between a connection point of the first and second switching elements and a connection point of the fifth and sixth diodes, and the third and fourth diodes. A smoothing capacitor connected in parallel with the switching element, a connection point between the first and second switching elements, and a connection point between the third and fourth switching elements A second inductor connected in series with a load circuit between the first and second switching elements, and an output terminal on the connection point side of the first and second switching elements among both output terminals of the AC power supply is a negative electrode; Forming a short-circuit closed loop of the load circuit via the second inductor through which current can flow from the connection point of the switching element to the connection point of the third and fourth switching elements through the load circuit and the second inductor; While turning on / off the first to fourth switching elements, and short-circuiting the AC power supply via the first inductor and canceling the short-circuit, the two output terminals of the AC power supply are connected. When the output terminal on the connection point side of the first and second switching elements is a positive electrode, the connection point of the third and fourth switching elements is connected to the load circuit and the load circuit. While avoiding the formation of a short-circuit closed loop of the load circuit via the second inductor through which current can flow toward the connection point of the first and second switching elements through the second inductor. A closed loop forming means for turning on / off the fourth switching element and short-circuiting the AC power supply via the first inductor and canceling the short-circuit.

In this configuration, when the output terminal on the connection point side of the first and second switching elements of the two output terminals of the AC power supply is a negative electrode, when the second and third switching elements are turned on, the load circuit In addition, the voltage across the smoothing capacitor is applied to the second inductor. At this time, for example, if the load circuit is constituted by the HID lamp and a capacitor connected in parallel with the HID lamp, and the HID lamp is in a high impedance state until the start of discharging, the capacitor connected in parallel with the HID lamp is ,
The battery is charged almost up to the voltage between both ends of the smoothing capacitor. In addition, the battery passes through the load circuit and the second inductor from the connection point of the first and second switching elements to the connection point of the third and fourth switching elements. As a result, a short-circuit closed loop of the load circuit via the second inductor through which a current can flow is not formed, so that a voltage substantially equal to the voltage across the smoothing capacitor is maintained. Even when the output terminal on the connection point side of the first and second switching elements of both output terminals of the AC power supply has a positive polarity, the capacitor connected in parallel with the HID lamp has a voltage substantially equal to the voltage across the smoothing capacitor. Therefore, a voltage suitable for starting is applied to both ends of the HID lamp. Accordingly, even if the load circuit is configured by the HID lamp and the capacitor connected in parallel with the HID lamp,
The startability of the ID lamp can be improved.

Further, since the closed loop forming means short-circuits the AC power supply via the first inductor and releases the short-circuit, magnetic energy is accumulated in the first inductor by the power from the AC power supply at the time of the short-circuit. When the short circuit is released, the smoothing capacitor is charged by the AC power supply and the first inductor that stores the magnetic energy, so that the step-up chopper operation is performed without using the first and second switching elements. Become like Thus, for example, a load circuit is formed by the HID lamp and a capacitor connected in parallel with the HID lamp, and the constant power characteristics and the constant power output can be maintained even when the lamp voltage of the HID lamp becomes higher than usual. become.

In addition, the closed loop forming means is provided with the fifth loop.
And a fifth and a sixth switching element respectively connected in parallel with the first and second switching elements, and when the output terminal on the connection point side of the first and second switching elements among the two output terminals of the AC power supply becomes a negative electrode, Turning on the second and third switching elements of the first to sixth switching elements, and then turning on the second and sixth switching elements of the first to sixth switching elements; While repeating a series of controls for turning off the switching element, when the output terminal on the connection point side of the first and second switching elements among both output terminals of the AC power supply becomes positive, the first to sixth switching operations are performed. Turning on the first and fourth switching elements among the elements;
Next, among the first to sixth switching elements, the first
And a control circuit that repeats a series of controls for turning on the fifth switching element and then turning off the first to sixth switching elements. According to this configuration, even if a load circuit is configured by, for example, an HID lamp and a capacitor connected in parallel with the HID lamp, the startability of the HID lamp can be improved, and the lamp voltage of the HID lamp is normally reduced. The constant power characteristic and the constant power output can be maintained even when the power becomes higher.

Further, the closed loop forming means includes a seventh switching element connected in parallel with the AC power supply and the first inductor, and the first switching element of both output terminals of the AC power supply.
And when the output terminal on the connection point side of the second switching element becomes negative, the second and third switching elements of the first to fourth and seventh switching elements are turned on, and then the first to fourth and A series of controls for turning on the seventh switching element of the seventh switching element and then for turning off the first to fourth and seventh switching elements is repeated, while the second of the two output terminals of the AC power source is repeatedly operated. When the output terminal on the connection point side of the first and second switching elements becomes positive, the first to fourth and seventh terminals
Turning on the first and fourth switching elements of the switching elements, then turning on the seventh switching element of the first to fourth and seventh switching elements, and then turning on the first to fourth and seventh switching elements And a control circuit for repeatedly performing a series of controls for turning off the element. According to this configuration, for example, HID
Even if a load circuit is constituted by the lamp and a capacitor connected in parallel with the HID lamp, it is possible to improve the startability of the HID lamp and to maintain a constant power even when the lamp voltage of the HID lamp becomes higher than usual. Characteristics and constant power output can be maintained.

Further, the seventh switching element may be a switching element capable of interrupting a current flowing bidirectionally through the seventh switching element. According to this configuration, the short-circuit of the AC power supply via the first inductor is performed regardless of whether the output terminal on the connection point side of the first and second switching elements among the two output terminals of the AC power supply is a negative electrode or a positive electrode. And this short circuit can be released.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of a power supply unit according to a first embodiment of the present invention, and FIGS. 2 and 3 are explanatory diagrams of a control circuit shown in FIG. A first embodiment will be described.

This power supply device comprises switching elements (first and second switching elements) S1, S2 connected in series.
Switching elements (third and fourth switching elements) S3 and S4 connected in series with these switching elements S1 and S2, and switching elements S1 to S4.
(First to fourth diodes) D1 to D4 connected in parallel with the switching elements S1 and S2, respectively.
Series-connected diodes (fifth and sixth diodes) D5 and D6 connected in parallel with the switching element S1,
S2 is connected in series with the AC power supply AC between the connection point of S2 and the connection point of the diodes D5 and D6, and one end is connected to the diode D
5, an inductor (first inductor) L1 connected to the connection point of D6, a smoothing capacitor C1 connected in parallel with the switching elements S3, S4, and a switching element S1,
An inductor (second inductor) L2 connected in series with the load circuit LD between the connection point of S2 and the connection point of the switching elements S3 and S4 is provided in the same manner as the power supply device shown in FIG. The circuit (closed loop forming means) 10 is further provided. The switching elements S1 to S4 are transistors or FET Q shown in FIG.
It may be 1 to Q4. In this case, according to the latter, since a structure including a parasitic diode corresponding to the diodes D1 to D4 is included, it is not necessary to separately provide a diode element. The load circuit LD includes an HID lamp La and a capacitor C2 connected in parallel with the HID lamp La, as in FIG.

The closed loop forming circuit 10 includes an AC power supply A
When the output terminal on the connection point side of the switching elements S1 and S2 among the two output terminals of C is a negative electrode, the switching elements S1 and S2
The switching is performed while avoiding the formation of a short-circuit closed loop of the load circuit LD via the inductor L2 through which the current can flow from the connection point of No. 2 to the connection point of the switching elements S3 and S4 through the load circuit LD and the inductor L2 respectively. The elements S1 to S4 are turned on / off, and the short-circuit of the AC power supply AC via the inductor L1 and the elimination of the short-circuit are performed. When the output terminal is positive, the load circuit LD via the inductor L2 through which the current can flow from the connection point of the switching elements S3 and S4 to the connection point of the switching elements S1 and S2 through the inductor L2 and the load circuit LD respectively. When the switching elements S1 to S4 are turned on / off while avoiding the formation of a short-circuit closed loop of In addition, the switching element (seventh switching element) S7 connected in parallel with the AC power supply AC and the inductor L1 is connected to the AC power supply AC and the inductor L1 in the first embodiment. , And a control circuit 11. Note that the switching element S7 is the switching element S
Any device capable of interrupting the current flowing in both directions through the device 7 may be used, such as a transistor or a relay.

When the output terminal on the connection point side of the switching elements S1 and S2 among the two output terminals of the AC power supply AC is negative, that is, the diode D5
When the current can be drawn from the output terminal on the connection point side of D6 into the present power supply device, the switching elements S2, S3 of the switching elements S1 to S4, S7 as shown in FIG.
Is turned on, and then the switching elements S1 to S4, S7
A series of control operations of turning on the switching element S7 and then turning off the switching elements S1 to S4 and S7 is repeated, while the output terminal on the connection point side of the switching elements S1 and S2 among the both output terminals of the AC power supply AC. Becomes positive, that is, when it becomes possible to draw current into the power supply from the output terminal that becomes positive, as shown in FIG. 3, the switching elements S1 and S4 of the switching elements S1 to S4 and S7 are turned on. And then the switching element S1
To turn on the switching element S7 among S4 and S7,
Next, a series of controls for turning off the switching elements S1 to S4 and S7 are repeatedly performed.

FIG. 4 is a diagram for explaining the operation of the present power supply device. The circuit operation of the first embodiment will be described with reference to FIG.

When the output terminal on the connection point side of the switching elements S1 and S2 of the two output terminals of the AC power supply AC is negative,
As shown in a period T1 of FIG. 2 and FIG. 4A, the switching element S out of the switching elements S1 to S4 and S7.
2, S3 is turned on.

When the switching elements S2 and S3 are turned on, the AC power supply AC serves as a power supply on the AC power supply AC side, and the AC power supply AC, the inductor L1, and the diode D
5. A current flows along a closed loop of the smoothing capacitor C1, the diode D2 and the AC power supply AC along this forward path. Thereby, the smoothing capacitor C1 is charged.

On the other hand, on the load circuit LD side, the smoothing capacitor C1 serves as a power source, and the smoothing capacitor C1, the switching element S3, the inductor L2, the load circuit LD, the switching element S2, and the closed loop of the smoothing capacitor C1 follow this forward path. Electric current flows. As a result, power is supplied to the load circuit LD and magnetic energy is stored in the inductor L2. Also, at this time, when the HID lamp La is in a high impedance state until the start of discharging, the capacitor C2 is rapidly charged by the smoothing capacitor C1 to almost the voltage across the smoothing capacitor C1.

Thereafter, when the period T1 elapses, as shown in the period T2 of FIG. 2 and FIG. 4B, the switching element S7 among the switching elements S1 to S4 and S7 is turned on.

When the switching element S7 is turned on, on the AC power supply AC side, the AC power supply AC serves as a power supply.
AC power supply AC, inductor L1, switching element S7
A current flows along a closed loop of the AC power supply AC along this forward path. Thereby, energy is stored in the inductor L1.

On the other hand, on the load circuit LD side, the energy accumulated in the inductor L2 during the period T1 causes the closed loop of the inductor L2, the load circuit LD, the switching element S7, the diode D5, the smoothing capacitor C1, the diode D4, and the inductor L2 to: A current flows through the inductor L2, the load circuit LD, the diode D1, the smoothing capacitor C1, the diode D4, and the closed loop of the inductor L2. Thus, the energy stored in the inductor L2 returns to the smoothing capacitor C1 while supplying power to the load circuit LD. Further, at this time, when the HID lamp La is in a high impedance state until the start of discharge, the connection point of the switching elements S1 and S2 passes through the load circuit LD and the inductor L2 to the connection point of the switching elements S3 and S4. Since a short-circuit closed loop of the load circuit LD via the inductor L2 through which current can flow is not formed, the capacitor C2 does not discharge in the short-circuit closed loop of the load circuit LD via the inductor L2. Therefore, the capacitor C2 can hold the voltage across the smoothing capacitor C1 obtained during the charging in the period T1.

Thereafter, when the energy stored in the inductor L2 is exhausted, as shown in FIG. 4C, a current flows only in the closed loop due to the turning on of the switching element S7.

Thereafter, when the period T2 elapses, as shown in a period T3 in FIG.
7 turns off.

When the switching elements S1 to S4 and S7 are turned off, the "AC power supply AC and inductor L1", the diode D5, the smoothing capacitor C1, the diode D2 and the "AC power supply AC and inductor L1" A current flows along a closed loop of the AC power supply AC and the inductor L1 along this forward path. Thus, the smoothing capacitor C1 is connected to the “AC power supply A
C and the inductor L1 ", the voltage at both ends is increased to the voltage level of the AC power supply AC or higher.

Thereafter, when the period T3 has elapsed, the series of operations in the periods T1 to T3 are repeated until the output terminal on the connection point side of the switching elements S1 and S2 among the two output terminals of the AC power supply AC becomes positive. It is.

Thereafter, when the output terminal on the connection point side of the switching elements S1 and S2 among the two output terminals of the AC power supply AC becomes positive, as shown in a period T1 in FIG. 3, the switching elements S1 to S4 and S7 are turned off. Switching elements S1 and S4
Turns on.

When the switching elements S1 and S4 are turned on, on the AC power supply AC side, the AC power supply AC serves as a power supply, and the AC power supply AC, the diode D1, the smoothing capacitor C1, the diode D6, the inductor L1, and the AC power supply AC are connected. Current flows along this path in the closed loop. Thereby, the smoothing capacitor C1 is charged.

On the other hand, on the load circuit LD side, the smoothing capacitor C1 serves as a power source, and the smoothing capacitor C1, the switching element S1, the load circuit LD, the inductor L2, the switching element S4, and the closed loop of the smoothing capacitor C1 follow this forward path. Electric current flows. As a result, power is supplied to the load circuit LD and magnetic energy is stored in the inductor L2. Further, at this time, when the HID lamp La is in a high impedance state until the start of discharging, the capacitor C2 is changed by the smoothing capacitor C1.
The battery is rapidly charged to almost the voltage across the smoothing capacitor C1 with a polarity opposite to that of the period T1 in FIG.

Thereafter, when the period T1 in FIG. 3 has elapsed, as shown in the period T2, the switching elements S1 to S4, S4
7, the switching element S7 is turned on.

When the switching element S7 is turned on, on the AC power supply AC side, the AC power supply AC serves as a power supply.
AC power supply AC, switching element S7, inductor L1
A current flows along a closed loop of the AC power supply AC along this forward path. Thereby, energy is stored in the inductor L1.

On the other hand, on the load circuit LD side, the period T in FIG.
By the energy stored in the inductor L2 at 1,
Inductor L2, diode D3, smoothing capacitor C
1, a closed loop of diode D6, switching element S7, load circuit LD and inductor L2, and inductor L
2. A current flows through the diode D3, the smoothing capacitor C1, the diode D2, the load circuit LD, and the closed loop of the inductor L2. Thus, the energy stored in the inductor L2 returns to the smoothing capacitor C1 while supplying power to the load circuit LD. Also, at this time, when the HID lamp La is in a high impedance state until the start of discharge, the connection point of the switching elements S3 and S4 passes through the inductor L2 and the load circuit LD, respectively, and then goes to the connection point of the switching elements S1 and S2. Since a short-circuit closed loop of the load circuit LD via the inductor L2 through which current can flow is not formed, the capacitor C2 does not discharge in the short-circuit closed loop of the load circuit LD via the inductor L2. Therefore, the capacitor C2 can substantially hold the voltage across the smoothing capacitor C1 obtained by charging during the period T1 in FIG.

Thereafter, when the energy stored in the inductor L2 is exhausted, the current flows only in the closed loop due to the turning on of the switching element S7.

Thereafter, when the period T2 in FIG. 3 elapses, as shown in the period T3 in FIG.
4, S7 is turned off.

When the switching elements S1 to S4 and S7 are turned off, the AC power supply AC and the inductor L1 that has accumulated energy during the period T2 in FIG.
Current flows along the closed loop of “C and inductor L1”, diode D1, smoothing capacitor C1, diode D6, and “AC power supply AC and inductor L1”. As a result, the smoothing capacitor C1 is charged by the “AC power supply AC and the inductor L1”, so that the voltage at both ends is boosted to the voltage level of the AC power supply AC or more.

Thereafter, when the period T3 in FIG. 3 elapses, the switching elements S1 and S1 of the two output terminals of the AC power supply AC are switched.
Until the output terminal on the connection point side of No. 2 becomes negative, T
A series of operations in a period from 1 to T3 is repeated.

As described above, according to the first embodiment, when the HID lamp La is in a high impedance state before the start of discharging, the capacitor C2 is substantially turned on both ends of the smoothing capacitor C1 by turning on the switching elements S2, S3 or S1, S4. After being charged to the voltage, the switching elements S1, S3 or S2, S2, like the conventional power supply shown in FIG.
Since no short circuit occurs through the inductor L2 when the switch 4 is turned on, a voltage suitable for starting can be applied to both ends of the HID lamp La. Thereby, the startability of the HID lamp La can be improved.

Further, an inductor L1, a diode D5,
D6, smoothing capacitor C1 and switching element S7
DC power supply circuit comprising switching elements S1-S
4. The boost chopper operation can be performed without using the switching elements S1 and S2 of the inverter circuit including the diodes D1 to D4 and the inductor L2.
The constant power characteristic and the constant power output can be maintained even when the lamp voltage of the ID lamp becomes higher than usual.

When the switching element S7 is turned on, the currents flowing in the closed loop on the AC power supply AC side and the closed loop on the load circuit LD side are opposite to each other, so that the loss in the switching element S7 can be reduced.

Further, since the step-up chopper circuit is constituted, it is possible to draw the input current from the AC power supply over the entire period. For example, if a filter circuit is provided on the AC power supply side, the input current harmonic distortion can be reduced. Can be suppressed.

FIG. 5 is a schematic configuration diagram of a power supply device according to a second embodiment of the present invention, and FIGS. 6 and 7 are explanatory diagrams of the control circuit shown in FIG. 5. The second embodiment will be described with reference to these drawings. Will be described.

This power supply device includes switching elements S1 to S1.
S4, diodes D1 to D6, inductors L1 and L2, and a smoothing capacitor C1 as in the first embodiment, and a closed loop forming circuit 2 different from the first embodiment.
0 is provided.

This closed-loop forming circuit 20 includes an AC power supply A
When the output terminal on the connection point side of the switching elements S1 and S2 among the two output terminals of C is a negative electrode, the switching elements S1 and S2
The switching is performed while avoiding the formation of a short-circuit closed loop of the load circuit LD via the inductor L2 through which the current can flow from the connection point of No. 2 to the connection point of the switching elements S3 and S4 through the load circuit LD and the inductor L2 respectively. The elements S1 to S4 are turned on / off, and the short-circuit of the AC power supply AC via the inductor L1 and the elimination of the short-circuit are performed. When the output terminal is positive, the load circuit LD via the inductor L2 through which the current can flow from the connection point of the switching elements S3 and S4 to the connection point of the switching elements S1 and S2 through the inductor L2 and the load circuit LD respectively. When the switching elements S1 to S4 are turned on / off while avoiding the formation of a short-circuit closed loop of Moni, and performs release of the AC power source AC short-circuit and the short circuit through the inductor L1, in the second embodiment, the diodes D5, D6 and the switching elements S5, S6 are connected in parallel, respectively, the control circuit 2
1. The switching element S
5, S6 may be the same FETs Q5 and Q6 as in FIG.
Alternatively, a transistor or the like may be used. In this case, according to the former, since a structure including a parasitic diode corresponding to the diodes D5 and D6 is included, it is not necessary to separately provide a diode element.

When the output terminal on the connection point side of the switching elements S1 and S2 among the two output terminals of the AC power supply AC becomes negative, the control circuit 21 switches the switching elements among the switching elements S1 to S6 as shown in FIG. S2, S3 are turned on, then the switching elements S1 to S6 are turned on, and then the switching elements S1 to S6 are turned off. Switching element S
When the output terminal on the connection point side of the switching elements S1 and S2 becomes positive, as shown in FIG. 7, the switching elements S1 and S4 of the switching elements S1 to S6 are turned on, and then the switching elements S1 and S1 of the switching elements S1 to S6. A series of controls for turning on S5 and then turning off the switching elements S1 to S6 are repeatedly performed.

FIG. 8 is a diagram for explaining the operation of the present power supply device. The circuit operation of the second embodiment will be described with reference to FIG.

When the output terminal on the connection point side of the switching elements S1 and S2 among the two output terminals of the AC power supply AC is negative,
As shown in a period T1 of FIG. 6 and FIG. 8A, the switching elements S2 and S
3 turns on. This is the same as in the first embodiment, so that the smoothing capacitor C1 is charged while the load circuit L
Power is supplied to D and magnetic energy is stored in inductor L2. Also, at this time, when the HID lamp La is in a high impedance state until the start of discharging, the capacitor C2 is rapidly charged by the smoothing capacitor C1 to almost the voltage across the smoothing capacitor C1.

Thereafter, when the period T1 elapses, as shown in the period T2 in FIG. 6 and FIG. 8B, the switching elements S2 and S6 among the switching elements S1 to S6 are turned on.

When the switching elements S2 and S6 are turned on, on the AC power supply AC side, the AC power supply AC becomes a power supply, and the AC power supply AC, the inductor L1, the switching element S6, the diode D2, and the closed loop of the AC power supply AC form this power supply. Current flows along the path. Thereby, energy is stored in the inductor L1.

On the other hand, on the side of the load circuit LD, a current decreases and flows through the closed loop of the inductor L2, the load circuit LD, the switching element S2, the diode D4, and the inductor L2 due to the energy stored in the inductor L2 during the period T1.

As a result, the currents flowing through the closed loop on the AC power supply AC side and the closed loop on the load circuit LD side become opposite to each other, so that the loss in the switching element S2 can be reduced. At this time, when the HID lamp La is in a high impedance state before the start of discharge, the switching element S3 passes through the load circuit LD and the inductor L2 from the connection point of the switching elements S1 and S2, respectively.
Inductor L2 through which current can flow toward the connection point of S4
Is not formed, the capacitor C2 does not discharge in the short-circuit closed loop of the load circuit LD via the inductor L2. Therefore, the capacitor C2 can hold the voltage across the smoothing capacitor C1 obtained during the charging in the period T1.

Thereafter, when the energy stored in the inductor L2 is exhausted, a current flows only in the closed loop on the AC power supply AC side as shown in FIG.

Thereafter, when the period T2 in FIG. 6 has elapsed, as shown in the period T3, the switching elements S1 to S6 are turned off.

When switching elements S1 to S6 are turned off, "AC power supply AC and inductor L1", diode D5, smoothing capacitor C1, diode D2, and AC power supply AC and inductor L1 that has accumulated energy during period T2 in FIG. A current flows in the closed loop of “AC power supply AC and inductor L1” along this forward path. Thus, the smoothing capacitor C1 is connected to the “AC power supply A
C and the inductor L1 ", the voltage at both ends is increased to the voltage level of the AC power supply AC or higher.

Thereafter, when the period T3 in FIG. 6 has elapsed, the switching elements S1 and S1 of the two output terminals of the AC power supply AC are switched.
Until the output terminal on the connection point side of No. 2 becomes a positive electrode, T in FIG.
A series of operations in a period from 1 to T3 is repeated.

Thereafter, when the output terminal on the connection point side of the switching elements S1 and S2 of the two output terminals of the AC power supply AC becomes positive, the switching elements S1 to S6 are switched as shown in a period T1 in FIG. The elements S1 and S4 are turned on. Since this is the same as in the first embodiment, the smoothing capacitor C1 is charged, while power is supplied to the load circuit LD and magnetic energy is accumulated in the inductor L2. At this time, when the HID lamp La is in a high impedance state before the start of discharge, the capacitor C2 is connected to the smoothing capacitor C1 for the period T in FIG.
1 and is rapidly charged to almost the voltage between both ends of the smoothing capacitor C1 with a polarity opposite to that of the case 1.

Thereafter, when the period T1 in FIG. 7 has elapsed, as shown in the period T2, the switching elements S1 and S5 of the switching elements S1 to S6 are turned on.

When the switching elements S1 and S5 are turned on, on the AC power supply AC side, the AC power supply AC is used as a power supply, and the AC power supply AC, the diode D1, the switching element S5, the inductor L1, and the AC power supply AC are closed. Current flows along the path. Thereby, energy is stored in the inductor L1.

On the other hand, on the load circuit LD side, the period T in FIG.
By the energy stored in the inductor L2 at 1,
Inductor L2, diode D3, switching element S
1. The current flows in the closed loop of the load circuit LD and the inductor L2 while decreasing.

As a result, the currents flowing through the closed loop on the AC power supply AC side and the closed loop on the load circuit LD side become opposite to each other, so that the loss in the switching element S1 can be reduced. Also, at this time, when the HID lamp La is in a high impedance state before the start of discharge, the switching elements S1 and S4 pass through the inductor L2 and the load circuit LD from the connection point of the switching elements S3 and S4, respectively.
Inductor L2 through which current can flow toward the connection point of S2
Is not formed, the capacitor C2 does not discharge in the short-circuit closed loop of the load circuit LD via the inductor L2. Therefore, the capacitor C2 can substantially hold the voltage across the smoothing capacitor C1 obtained by charging during the period T1 in FIG.

Thereafter, when the energy stored in the inductor L2 is exhausted, a current flows only in the closed loop on the AC power supply AC side.

Thereafter, when the period T2 in FIG. 7 elapses, as shown in the period T3, the switching elements S1 to S6 are turned off.

When switching elements S1 to S6 are turned off, "AC power supply AC and inductor L1", diode D1, smoothing capacitor C1, diode D6 and AC power supply AC and inductor L1 which has accumulated energy during period T2 in FIG. A current flows in the closed loop of “AC power supply AC and inductor L1” along this forward path. Thus, the smoothing capacitor C1 is connected to the “AC power supply A
C and the inductor L1 ", the voltage at both ends is increased to the voltage level of the AC power supply AC or higher.

Thereafter, when the period T3 in FIG. 7 elapses, the switching elements S1 and S
Until the output terminal on the connection point side of No. 2 becomes negative, T
A series of operations in a period from 1 to T3 is repeated.

As described above, according to the first embodiment, when the HID lamp La is in a high impedance state until the start of discharging, the capacitor C2 is substantially turned on both ends of the smoothing capacitor C1 by turning on the switching elements S2, S3 or S1, S4. After being charged to the voltage, the switching elements S1, S3 or S2, S2, like the conventional power supply shown in FIG.
Since no short circuit occurs through the inductor L2 when the switch 4 is turned on, a voltage suitable for starting can be applied to both ends of the HID lamp La. Thereby, the startability of the HID lamp La can be improved.

The inductor L1, the diode D5,
D6, smoothing capacitor C1 and switching element S
DC power supply circuit composed of switching elements S1 to S4, diodes D1 to D4 and inductor L
2 switching elements S1,
Regardless of the ON / OFF state of S2, the diodes D1, D
Since the step-up chopper operation can be performed only by using No. 2, the constant power characteristic and the constant power output can be maintained even when the lamp voltage of the HID lamp becomes higher than usual.

When the switching elements S2 and S6 are turned on and when the switching elements S1 and S5 are turned on, currents flowing through the closed loop on the AC power supply AC side and the closed loop on the load circuit LD side are mutually switched in the switching elements S2 and S1. The switching element S
2. The loss in S1 can be reduced.

Further, since the step-up chopper circuit is configured, it is possible to draw the input current from the AC power supply over the entire period. For example, if a filter circuit is provided on the AC power supply side, the input current harmonic distortion can be reduced. Can be suppressed.

Although the present power supply device is suitable for a load circuit composed of an HID lamp and a capacitor connected in parallel with the HID lamp, it can be used for various load circuits. Needless to say.

[0084]

As is apparent from the above, according to the first aspect of the present invention, the first and second switching elements connected in series, and the series connected in parallel with the first and second switching elements. Connected third and fourth switching elements, first to fourth diodes respectively connected in parallel with the first to fourth switching elements, and third and fourth diodes connected in series with the first and second switching elements. Fifth and sixth diodes, a first inductor connected in series with an AC power supply between a connection point of the first and second switching elements and a connection point of the fifth and sixth diodes, and A smoothing capacitor connected in parallel with the fourth switching element, a connection point between the first and second switching elements, and a connection point between the third and fourth switching elements A second inductor connected in series with a load circuit between the first and second switching elements, and an output terminal on the connection point side of the first and second switching elements among both output terminals of the AC power supply is a negative electrode; Forming a short-circuit closed loop of the load circuit via the second inductor through which current can flow from the connection point of the switching element to the connection point of the third and fourth switching elements through the load circuit and the second inductor; While turning on / off the first to fourth switching elements, and short-circuiting the AC power supply via the first inductor and canceling the short-circuit, the two output terminals of the AC power supply are connected. When the output terminal on the connection point side of the first and second switching elements is a positive electrode, the connection point of the third and fourth switching elements is connected to the load circuit and the load circuit. While avoiding the formation of a short-circuit closed loop of the load circuit via the second inductor through which current can flow toward the connection point of the first and second switching elements through the second inductor. A closed loop forming means for turning on / off the fourth switching element and short-circuiting the AC power supply via the first inductor and canceling the short-circuit is provided. For example, the HID lamp and the HID lamp are connected in parallel. Even if a load circuit is constituted by a capacitor, the startability of the HID lamp can be improved, and the constant power characteristics and the constant power output can be maintained even when the lamp voltage of the HID lamp becomes higher than usual. Becomes possible.

According to the second aspect of the present invention, the closed loop forming means includes a fifth and a sixth switching element connected in parallel with the fifth and the sixth diode, respectively.
When the output terminal on the connection point side of the first and second switching elements of both the output terminals of the AC power supply becomes a negative electrode, the second and third switching elements of the first to sixth switching elements become negative.
While repeating a series of control to turn on the switching element, then turn on the second and sixth switching elements of the first to sixth switching elements, and then turn off the first to sixth switching elements, When the output terminal on the connection point side of the first and second switching elements among the two output terminals of the AC power supply has a positive polarity, the first to the first are output.
Turning on the first and fourth switching elements of the sixth switching element, then turning on the first and fifth switching elements of the first to sixth switching elements, and then turning on the first to sixth switching elements And a control circuit that repeats a series of controls for turning off the HID lamp, so that the startability of the HID lamp can be improved even if, for example, a load circuit is constituted by the HID lamp and a capacitor connected in parallel with the HID lamp. And the constant power characteristic and the constant power output can be maintained even if the lamp voltage of the HID lamp becomes higher than usual.

According to the third aspect of the present invention, the closed loop forming means includes a seventh switching element connected in parallel with the AC power supply and the first inductor, and the first and second output terminals of the AC power supply. When the output terminal on the connection point side of the second switching element becomes negative, the second and third switching elements of the first to fourth and seventh switching elements are turned on, and then the first to fourth and fourth switching elements are turned on. While repeating a series of controls for turning on the seventh switching element among the seven switching elements and then turning off the first to fourth and seventh switching elements,
When the output terminal on the connection point side of the first and second switching elements among the two output terminals of the AC power supply has a positive polarity, the first of the first to fourth and seventh switching elements is
And a fourth switching element, a series of turning on the seventh switching element among the first to fourth and seventh switching elements, and then turning off the first to fourth and seventh switching elements. Since a control circuit for repeating control is provided, even if a load circuit is constituted by, for example, an HID lamp and a capacitor connected in parallel with the HID lamp, it is possible to improve the startability of the HID lamp and to improve the startability of the HID lamp. It is possible to maintain the constant power characteristic and the constant power output even when the lamp voltage becomes higher than usual.

According to the fourth aspect of the present invention, since the seventh switching element is a switching element capable of interrupting a current flowing bidirectionally through the seventh switching element, the seventh switching element is one of the two output terminals of the AC power supply. Regardless of whether the output terminal on the connection point side of the first and second switching elements is a negative electrode or a positive electrode, it is possible to short-circuit the AC power supply via the first inductor and release the short-circuit.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a power supply device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a control circuit shown in FIG.

FIG. 3 is an explanatory diagram of a control circuit shown in FIG.

FIG. 4 is an operation explanatory diagram of the power supply device according to the first embodiment.

FIG. 5 is a schematic configuration diagram of a power supply device according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of the control circuit shown in FIG.

FIG. 7 is an explanatory diagram of the control circuit shown in FIG.

FIG. 8 is an operation explanatory diagram of the power supply device according to the second embodiment.

FIG. 9 is a schematic configuration diagram of a power supply device adopting a dual-purpose chopper method.

FIG. 10 is a schematic configuration diagram of another power supply device.

[Explanation of symbols]

 10, 20 Closed loop forming circuit 11, 21 Control circuit S5 to S7 Switching element S1 to S4 Switching element D1 to D6 Diode L1, L2 Inductor C1 Smoothing capacitor LD Load circuit La HID lamp C2 Capacitor

Claims (4)

[Claims] A first and a second switching element connected in series, a third and a fourth switching element connected in series with the first and second switching elements, and the first to fourth switching elements. First to fourth diodes respectively connected in parallel with each other, fifth and sixth diodes connected in series with the first and second switching elements, and a connection point between the first and second switching elements. A first inductor connected in series with an AC power supply between the connection point of the fifth and sixth diodes, a smoothing capacitor connected in parallel with the third and fourth switching elements, and a first and second switching; A second inductor connected in series with a load circuit between a connection point of the element and a connection point of the third and fourth switching elements; When the output terminal on the connection point side of the first and second switching elements of both output terminals of the AC power supply is a negative electrode, the output terminal passes through the load circuit and the second inductor from the connection point of the first and second switching elements. And the third and fourth
While turning on / off the first to fourth switching elements while avoiding formation of a short-circuit closed loop of the load circuit via the second inductor through which a current can flow toward a connection point of the switching elements, While short-circuiting the AC power supply and canceling the short-circuit through one inductor, when the output terminal on the connection point side of the first and second switching elements among both output terminals of the AC power supply is a positive electrode,
The load via the second inductor through which a current can flow from the connection point of the third and fourth switching elements through the load circuit and the second inductor toward the connection point of the first and second switching elements. Closed-loop forming means for turning on / off the first to fourth switching elements while avoiding formation of a short-circuit closed loop of a circuit, and for short-circuiting the AC power supply via the first inductor and canceling the short-circuit; A power supply device comprising: 2. The closed loop forming means includes: fifth and sixth switching elements connected in parallel with the fifth and sixth diodes, respectively; and the first and second switching elements of both output terminals of the AC power supply. When the output terminal on the connection point side becomes negative, the second and third switching elements of the first to sixth switching elements become
While repeating a series of control to turn on the switching element, then turn on the second and sixth switching elements of the first to sixth switching elements, and then turn off the first to sixth switching elements, When the output terminal on the connection point side of the first and second switching elements among the two output terminals of the AC power supply has a positive polarity, the first to the first are output.
Turning on the first and fourth switching elements of the sixth switching element, then turning on the first and fifth switching elements of the first to sixth switching elements, and then turning on the first to sixth switching elements The power supply device according to claim 1, further comprising: a control circuit that repeats a series of controls for turning off the power supply. 3. The closed loop forming means includes: a seventh switching element connected in parallel with the AC power supply and the first inductor; and a connection point side of the first and second switching elements among both output terminals of the AC power supply. When the output terminal becomes negative, the second of the first to fourth and seventh switching elements
And a third switching element, a series of turning on the seventh switching element among the first to fourth and seventh switching elements, and then turning off the first to fourth and seventh switching elements. While repeating the control, the first of the two output terminals of the AC power supply
And when the output terminal on the connection point side of the second switching element becomes positive, turns on the first and fourth switching elements among the first to fourth and seventh switching elements, and then turns on the first to fourth and 2. A control circuit that repeats a series of controls for turning on the seventh switching element among the seventh switching elements and then turning off the first to fourth and seventh switching elements.
The power supply as described. 4. The power supply device according to claim 3, wherein the seventh switching element is a switching element capable of interrupting a current flowing bidirectionally through the seventh switching element.