JP2001112253A - DC-to-DC CONVERTER - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC-to-DC converter which is applicable to a wide range of input voltage and controls wide ranges of output voltage and output power and is highly efficient and of small size. SOLUTION: Switching elements Q1 and Q2 are on/off-controlled by a controlling means not shown. The controlling means is so constituted as to be capable of controlling both the switching frequency and duty of the switching elements Q1 and Q2. A resonance circuit is composed of a choke coil L1, the leakage inductance of a transformer T, and a capacitor C21 (or C22). The controlling means is provided with two control modes for the switching elements Q1 and Q2: second mode in which the on-durations of Q1 and Q2 do not overlap and the switching elements are alternately turned on and off at a frequency close to the resonance frequency of the resonance circuit and first mode in which the duty is increased to a value higher than 50% when the switching elements Q1 and Q2 are alternately turned on and there is a duration when both the switching elements Q1 and Q2 are simultaneously on.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-DC converter.

[0002]

2. Description of the Related Art Conventionally, HIDs have been used as headlights for vehicles.
Lamps (high-intensity discharge lamps) are used. A discharge lamp lighting device for lighting this type of HID lamp includes a DC power supply of 12 V DC or 24 V DC composed of a storage battery, a DC-DC converter for converting (boosting) the output voltage of the DC power supply to a predetermined DC voltage, and a DC-DC converter. An inverter device that converts the output of the DC converter into an alternating rectangular wave voltage and outputs the voltage. Here, the HID lamp is
When the voltage required for steady (stable) lighting is _VL ,
A high voltage of 2.5 V _L or more is required at startup. Also,
The HID lamp has a negative load characteristic and a low lamp voltage during a period from the start of discharge to stable lighting, but when used for an application such as a headlight of a vehicle, it is necessary to speed up the rise of the luminous flux, When power required at the time of steady lighting (the rated power) and W _L, require the lamp power of about 2W _L after the start discharge, then the stable lighting by settles at the rated power W _L lamp power gradually decreases State.

As a DC-DC converter, for example, a DC-DC converter having a circuit configuration shown in FIG. 24 has been proposed.
p560).

[0004] A DC-DC converter (hereinafter referred to as a power supply device of Conventional Example 1) shown in FIG. 24 includes a transformer T having an intermediate tap on each of a primary winding N1 side and a secondary winding N2 side, and a DC power supply. A choke coil L1 connected between the positive electrode side of E and an intermediate tap of the primary winding N1, and a switching element including a transistor connected between both ends of the primary winding N1 and the negative electrode side of the DC power supply E, respectively. Q1,
Q2, a series circuit of a pair of rectifying diodes D21 and D21 is connected between both ends of the secondary winding N2, and a connection point between the diodes D21 and D22 and an intermediate tap between the secondary winding N2. An output capacitor C4 is connected between the first and second capacitors, and a load R _L is connected in parallel to the capacitor C4. In the power supply device of the first conventional example, when the switching elements Q1 and Q2 are alternately turned on and off, energy is accumulated in the choke coil L1 during a period in which the switching elements Q1 and Q2 are overlapped and on, and the switching elements Q1 and Q2 are turned on. Since the switching elements Q1 and Q2 are turned on and off so that the energy stored in the choke coil L1 is released when one of the two elements Q2 is turned off, the choke coil L1 and the switching element Q1,
Q2 is an inductance element for the boost chopper,
It functions as a switching element and can easily cope with heavy loads.

[0005] Japanese Patent Application Laid-Open No. 3-65061 discloses that
Wide range of input voltage (DC12V ~ DC2 as DC power supply
DC-DC with the purpose of supplying necessary power to a load with a small power loss that can cope with a 4V storage battery)
Converters have been proposed. This DC-DC converter (hereinafter referred to as a power supply device of Conventional Example 2) rectifies an AC output generated on an L push-pull type inverter circuit and a secondary side of a transformer of the inverter circuit and supplies the rectified output to a load. And a rectifier circuit composed of a voltage doubler circuit. In the power supply device of Conventional Example 2, since both switching elements of the inverter circuit are alternately turned on and off while providing a period in which both switching elements are on, it is easy to cope with a heavy load. .

Japanese Unexamined Patent Publication No. 1-318577 discloses a motor control inverter device having a plurality of switching elements Qa to Qb as shown in FIG. Example 3
Is referred to as a power supply device). In the power supply device of the third conventional example, the switching elements Qa,
The power can be controlled by providing a period during which both Qb are turned on and appropriately controlling the period of the boost mode in which energy is stored in the choke coils L3 and L4. Conventional example 3
In this power supply device, a DC power supply is obtained by rectifying an AC power supply AC such as a commercial power supply with a rectifier circuit DB.

Japanese Patent Application Laid-Open No. Hei 4-269 discloses FIG.
As shown in FIG. 6, a pair of switching elements Q11, Q1
2 series circuits and a pair of switching elements Q13, Q1.
4 is connected between both ends of the series circuit of the DC power supply E and the choke coil L1, and the switching element Q1
1 and Q12 and switching elements Q13 and Q14
Full-bridge type inverter circuit in which a load _RL is connected between the power supply device and a connection point (hereinafter referred to as a power supply device of Conventional Example 4)
Has been proposed. In the power supply device of the fourth conventional example, when the switching elements Q11 and Q14 are on, the switching element Q12 is turned on and off at a high frequency, and when the switching element Q12 is on, the DC power supply E → the choke coil L1 →
The current flows through the path of the switching element Q11 → the switching element Q12 → the DC power supply E, so that the choke coil L1
When the switching element Q12 is turned off, the energy of the choke coil L1 is supplied to the load _RL through the path of the DC power supply E → the choke coil L1 → the switching element Q11 → the load _RL → the switching element Q14 → the DC power supply E. When switching elements Q12 and Q13 are on, switching element Q14 is turned on and off at a high frequency, and when switching element Q14 is on, DC power supply E →
Energy is stored in the choke coil L1 through the path of the choke coil L1, the switching element Q13, the switching element Q14, and the DC power supply E. When the switching element Q14 is turned off, the DC power supply E → the choke coil L1 → the switching element Q13 → the load _RL. → Switching element Q12
→ The energy of the choke coil L1 is supplied to the load _RL through the path of the DC power supply E.

[0008] Japanese Patent Publication No. 1-1919 discloses a discharge lamp lighting device (hereinafter referred to as a power supply of prior art 5) capable of supplying optimum power at the time of starting and steady lighting of a discharge lamp such as a fluorescent lamp. (Referred to as an apparatus). Conventional example 5
Is a push-pull type inverter as shown in FIG. 27, which has a rectifier circuit DB for rectifying an AC power supply AC such as a commercial power supply to obtain a DC voltage, and an intermediate tap in the primary winding N1. A transformer T, a choke coil L1 connected between the positive electrode side of the rectifier circuit DB and an intermediate tap of the transformer T, and a choke coil L1 connected between both ends of the primary winding N1 of the transformer T and the negative electrode of the rectifier circuit DB, respectively. Switching elements Q1 and Q2 comprising
1 and a resonance capacitor Cb connected between both ends of a primary winding N1 via a contact r1 of a relay Ry.
The current limiting inductor L _B across the secondary winding N2, via the L _B connects the discharge lamp La, the switching elements Q1, Q
2 is turned on and off alternately by the output of the feedback winding N3 to perform self-excited oscillation, and to generate a resonance voltage at both ends of the capacitor Ca by resonance with the inductance component of the transformer T. In the discharge lamp lighting device of the conventional example 5, immediately after the AC power supply AC is turned on, the relay Ry is not excited and the contact r1 is not energized.
Is switched to the Nc side, the resonance capacitor Cb is disconnected, and a high voltage sufficient to start the discharge lamp La is induced in the secondary winding N2 of the transformer T, so that the discharge lamp La Is turned on, and thereafter, when the voltage across the capacitor C17 increases and the trigger element 22 becomes conductive, the transistor Tr is turned on, the relay Ry is excited, the contact r1 is switched to the No side, and the primary winding N1 of the transformer T1 is turned on. Two capacitors Ca and Cb for resonance are connected between both ends, and the voltage induced in the secondary winding N2 of the transformer T decreases.

[0009]

SUMMARY OF THE INVENTION The above conventional examples 1 to
The power supply device 5 requires a high voltage of 2.5 V _L or more at the time of starting (at a light load) like a HID lamp, for example, and at the time of low voltage from starting (discharge start) to stable lighting.
W _L loads requiring power of about (i.e., the load the load condition greatly changes) not suitable for use as a power supply, in order to be able to handle the load, such as HID lamps, transformer T Therefore, it is necessary to design such that the turn ratio is increased and the maximum output capability is also increased, and there is a problem that the apparatus becomes large and expensive.

In the power supply device of the fifth prior art shown in FIG. 27, there is no means for freely controlling the power supplied to the discharge lamp La as a load to a desired value, and the design is fixed by the constants of the circuit components. Becomes In order to make the power supplied to the discharge lamp La variable, it is conceivable that the capacitors Ca and Cb can be made variable by using high-withstand-voltage variable capacitors. Is large and expensive, which leads to an increase in the size and cost of the apparatus. In the discharge lamp lighting device shown in FIG. 27, the switching elements Q1, Q2
Since the base drive current is fixed, the width in which the output power can be controlled cannot be widened, and is not suitable for power control during heavy loads from start to lighting, such as HID lamps.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a high-efficiency and small-sized DC power supply having a wide application range of input voltage and a wide control range of output voltage and output power.
-To provide a DD converter.

[0012]

In order to achieve the above object, the invention according to claim 1 comprises a DC voltage source and at least two switching elements each forming a closed loop together with the DC voltage source and an inductance element. An inverter circuit that converts an output voltage of the DC voltage source into an AC output and outputs the AC voltage to a secondary winding side of a transformer; and a resonance capacitor that forms a resonance circuit with the transformer and the inductance element. The circuit is
The period in which the at least two switching elements are turned on in an overlapping manner and energy is stored in the inductance element, and one of the at least two switching elements is turned off and the stored energy in the inductance element is stored in the DC voltage source. A first mode having a period superimposed on energy and released to the primary winding of the transformer;
A second mode in which the at least two switching elements do not turn on in an overlapping manner and are alternately turned on and off at a frequency near the resonance frequency of the resonance circuit. When operating in the mode, the at least two switching elements function as switching elements of the step-up chopper. Therefore, by adjusting a period in which the at least two switching elements are overlapped and on, the secondary voltage of the transformer is reduced. It is possible to control and obtain a large power, and when the inverter circuit operates in the second mode, the at least two switching elements do not overlap and turn on at a frequency near the resonance frequency of the resonance circuit. Since they are turned on and off alternately, even if the value of the input voltage changes, the switching frequency By adjusting the on-duty, the output voltage and output power can be controlled and a high voltage can be obtained.The output voltage and output power can be controlled without changing the constant of the capacitor. The applicable range and the control range of output voltage and output power are wide, and high efficiency and miniaturization can be achieved.
In the case of a load whose load state changes greatly, such as an ID lamp, it operates in the first mode when the load is heavy and the second mode when the load is light.
By operating in the mode described above, it can be used as a power supply device for a load whose load state greatly changes, such as an HID lamp.

According to a second aspect of the present invention, there is provided a DC voltage source, and at least two switching elements each forming a closed loop together with the DC voltage source and the inductance element, and converting an output voltage of the DC voltage source into an AC output. An inverter circuit that outputs to the secondary winding side of the transformer, a resonance capacitor that forms a resonance circuit with the transformer and the inductance element, and an output voltage of the inverter circuit that is converted into a predetermined DC voltage and supplied to a load. A rectifier circuit, wherein the inverter circuit is configured such that the at least two switching elements are turned on in an overlapping manner and energy is accumulated in the inductance element, and one of the at least two switching elements is turned off. The stored energy of the inductance element is converted to the energy of the DC voltage source. A first mode having a period of being folded and discharged to the primary winding of the transformer, and the at least two switching elements are not turned on in an overlapping manner and are alternately turned on and off at a frequency near the resonance frequency of the resonance circuit. And a second mode.
When the inverter circuit operates in the first mode, the at least two switching elements function as switching elements of the step-up chopper.
By adjusting the period during which the two switching elements are on in an overlapping manner, it is possible to control the secondary voltage of the transformer and obtain large power, and the inverter circuit
In the mode of operation, the at least two switching elements do not turn on in an overlapping manner and are alternately turned on and off at a frequency near the resonance frequency of the resonance circuit. By adjusting the switching frequency and on-duty, the output voltage and output power can be controlled and a high voltage can be obtained, and the output voltage and output power can be controlled without changing the capacitor constant. The application range of the input voltage and the control range of the output voltage and the output power are wide, high efficiency and small size can be achieved. By operating in the second mode at a light load with the operation in the mode, the load of the load, such as the HID lamp, whose load state changes greatly can be reduced. It can be used as a source device.

According to a third aspect of the present invention, in the first aspect of the present invention, there is provided a control means for controlling on / off of each of the switching elements, wherein the control means makes the voltage of the DC voltage source lower than a predetermined threshold value. When the inverter circuit is operated in the first mode when it is necessary to supply a low power to the load and the power is larger than the rated power, the inverter circuit operates even when the voltage of the DC voltage source is lower than a predetermined threshold. Power can be supplied.

According to a fourth aspect of the present invention, in the discharge lamp according to the first aspect of the present invention, the load requires a larger amount of power in a transition period from the start of discharging to the stable lighting as compared with the stable lighting. Control means for controlling the on / off of the element, wherein the control means operates the inverter circuit in the first mode during the transition period, so that even if the load is, for example, an HID lamp, from the start of discharge to stable lighting. It is possible to supply a large amount of electric power required during the transition period.

According to a fifth aspect of the present invention, in the first aspect of the present invention, there is provided a control means for controlling ON / OFF of each of the switching elements, wherein the control means controls the inverter circuit to the second state at light load or no load. , The necessary high voltage can be supplied to the load at light load or no load.

According to a sixth aspect of the present invention, in the first aspect of the invention, the load is a discharge lamp, and the load includes a control means for controlling on / off of each of the switching elements. Since the inverter circuit is operated in the second mode at the time of starting or dimming, it is possible to obtain an output voltage and output power required at the time of starting discharging or dimming of the discharge lamp.

According to a seventh aspect of the present invention, in the second aspect of the present invention, there is provided a control means for controlling on / off of each of the switching elements, wherein the control means makes the voltage of the DC voltage source lower than a predetermined threshold value. When the inverter circuit is operated in the first mode when it is necessary to supply a low power to the load and the power is larger than the rated power, the inverter circuit operates even when the voltage of the DC voltage source is lower than a predetermined threshold. Power can be supplied.

According to an eighth aspect of the present invention, in the discharge lamp according to the second aspect of the present invention, the load requires a larger amount of power in a transition period from the start of discharge to the stable lighting as compared with the stable lighting. Control means for controlling the on / off of the element, wherein the control means operates the inverter circuit in the first mode during the transition period, so that even if the load is, for example, an HID lamp, from the start of discharge to stable lighting. It is possible to supply a large amount of electric power required during the transition period.

In a ninth aspect of the present invention, in accordance with the second aspect of the present invention, there is provided a control means for controlling on / off of each of the switching elements, wherein the control means controls the inverter circuit to the second state at light load or no load. , The required high voltage can be supplied to the load at light load or no load.

According to a tenth aspect of the present invention, in the second aspect of the present invention, the load is a discharge lamp, and a control means for controlling on / off of each of the switching elements is provided. Since the inverter circuit is operated in the second mode at the time of starting or dimming, it is possible to obtain an output voltage or output power required at the time of starting discharging or dimming of the discharge lamp.

According to an eleventh aspect, in the first to tenth aspects, the inverter circuit has a choke coil as the inductance element on an input side.

According to a twelfth aspect of the present invention, in the first to tenth aspects, the inverter circuit is a push-pull type inverter circuit having a choke coil as the inductance element on an input side.

According to a thirteenth aspect, in the first to tenth aspects, the inverter circuit is a full-bridge type inverter circuit having a choke coil as the inductance element on an input side.

According to a fourteenth aspect of the present invention, in the first to tenth aspects of the present invention, the inverter circuit is a full-bridge type inverter circuit having a choke coil as the inductance element on an input side. Is a four simultaneous ON mode in which at least two switching elements are turned on in an overlapping manner, and four switching elements of an inverter circuit are turned on in an overlapping manner;
Two simultaneous ON mode in which two switching elements of one of the arms are turned on in an overlapping manner.
A mode selected from a sequential switching-on mode in which a period in which one switching element is turned on in an overlapped manner and a period in which two switching elements of the other arm are turned on in an overlapping manner are alternately provided. I do.

According to a fifteenth aspect of the present invention, in the first to tenth aspects, the inverter circuit is a full-bridge type inverter circuit having a choke coil as the inductance element on the input side, and the first mode Is a dual simultaneous ON mode in which at least two switching elements are turned on in an overlapping manner, and two switching elements in one of the arms are turned on in an overlapping manner, and two switching elements in one arm are turned on in an overlapping manner. A sequential switching on mode in which a period for turning on and a period for turning on two switching elements of the other arm are alternately provided, and a mode selected from three simultaneous on modes in which three switching elements are turned on in an overlapping manner. It is characterized by adoption.

According to a sixteenth aspect of the present invention, in the first to fifteenth aspects, the resonance capacitor is provided on a primary side of the transformer.

A seventeenth aspect of the present invention is characterized in that, in the first to fifteenth aspects of the present invention, the resonance capacitor is provided on a secondary side of the transformer.

According to an eighteenth aspect of the present invention, in the second aspect, the rectifier circuit is a voltage doubler rectifier circuit connected between both ends of a secondary winding of the transformer, and a capacitor of the voltage doubler rectifier circuit is provided. Also serves as the resonance capacitor, so there is no need to separately provide the resonance capacitor, and the number of components can be reduced.

According to a nineteenth aspect, in the eighteenth aspect, diodes are connected in anti-parallel between both ends of each capacitor of the voltage doubler rectifier circuit. Full-wave rectification operation is ensured under load.

According to a twentieth aspect, in the second aspect, the rectifier circuit is a full-wave rectifier circuit comprising a diode bridge connected between both ends of a secondary winding of the transformer. A capacitor input type smoothing circuit connected between the output terminals of the rectifier circuit is provided.Since the capacitor of the capacitor input type smoothing circuit also serves as the resonance capacitor, the AC component is removed by the capacitor input type smoothing circuit. In addition, since the capacitor of the capacitor input type smoothing circuit also serves as the resonance capacitor, it is not necessary to separately provide a resonance capacitor, and the number of components can be reduced.

According to a twenty-first aspect, in the second aspect, the rectifier circuit is a full-wave rectifier circuit including a diode bridge connected between both ends of a secondary winding of the transformer. A choke coil connected between the output terminals of the rectifier circuit and a series circuit of a smoothing capacitor, wherein the resonance capacitor is connected between both ends of the secondary winding on the input side of the full-wave rectifier circuit. Therefore, an AC component can be removed by a series circuit of a choke coil connected between the output terminals of the full-wave rectifier circuit and a smoothing capacitor.

According to a twenty-second aspect, in the first to fifteenth aspects, the transformer has a plurality of secondary windings.

According to a twenty-third aspect, in the first to fifteenth aspects, the transformer has a plurality of secondary windings, and the resonance capacitor is provided for each secondary winding. Therefore, power can be simultaneously supplied to a plurality of loads.

According to a twenty-fourth aspect, in the first to fifteenth aspects, the transformer has two secondary windings, and a rectifying diode is provided between both ends of each secondary winding. Since a load is inserted and the resonance capacitor is inserted between both ends of each secondary winding, power can be simultaneously supplied to a plurality of loads.

According to a twenty-fifth aspect of the present invention, in the first aspect of the present invention, the resonance capacitor is connected between both ends of the secondary winding of the transformer, and a DC cutoff is provided between both ends of the resonance capacitor. It is characterized in that a load is connected via a capacitor.

According to a twenty-sixth aspect of the present invention, there is provided a DC voltage source, and two switching elements each forming a closed loop together with the DC voltage source and an inductance element. An inverter circuit that outputs to the secondary winding side, a resonance capacitor that forms a resonance circuit with the transformer and the inductance element, and converts an output voltage of the inverter circuit into a predetermined DC voltage and supplies the DC voltage to a load A rectifier circuit, wherein the inverter circuit alternately turns on and off both switching elements at a duty exceeding 50% and stores energy in the inductance element during a period in which both switching elements are turned on in an overlapping manner; One turns off and the stored energy in the inductance element A first mode superimposed on the energy of the source and emitted to the primary winding of the transformer, a flyback converter is constituted by one switching element and the transformer, and a forward converter is constituted by the other switching element and the transformer. And a second mode in which each switching element is turned on and off.
By operating in the second mode, a high voltage of small power can be obtained with high efficiency, and by operating in the first mode under heavy load, large power can be supplied.

According to a twenty-seventh aspect of the present invention, a DC current source, a capacitor connected in parallel to the DC current source, and two switching elements forming a closed loop together with the DC current source via respective primary windings of a transformer. An inverter circuit that converts the output current of the DC current source into an AC output and supplies the AC current to a load on a secondary winding side of a transformer; and an inductance element that forms a resonance circuit with the capacitor. , Each switching element is 50
A first mode in which a period in which the switching element is alternately turned on and off with a duty of less than% and overlapped off is provided, and each switching element is alternately turned on and off at a frequency near the resonance frequency of the resonance circuit with a duty of 50%. The second mode is characterized by having the second mode, and by operating in the first mode at the time of no load and at the time of light load, a necessary high voltage can be applied to the load, and at the time of heavy load By operating in the second mode, the load power can be increased at a low voltage.

According to a twenty-eighth aspect of the present invention, a DC current source, a capacitor connected in parallel to the DC current source, and two switching elements forming a closed loop together with the DC current source via primary windings of a transformer, respectively. An inverter circuit that converts the output current of the DC current source into an AC output and outputs the AC current to the secondary winding side of a transformer; and an inductance element that forms a resonance circuit with the capacitor. A first mode in which each switching element operates as a flyback type converter together with a primary winding connected in series, and a second mode in which each switching element operates as a push-pull inverter in which each switching element is turned on and off at a duty of 50%. Characterized in that the first mode is used when there is no load and when there is a light load. By work, high voltage low power can be obtained efficiently, by operating in the second mode to the heavy load, it is possible to obtain a high current low voltage.

[0040]

(Embodiment 1) DC of this embodiment
The DC converter has a push-pull converter configuration as shown in FIG.
An inverter circuit INV that converts an output voltage of the DC power supply E into an AC output and outputs the AC output; and a rectifier circuit A that rectifies and smoothes the AC output of the inverter INV and outputs the result.
The load _RL is connected between the output terminals of the rectifier circuit A. An input capacitor C1 is connected in parallel between both ends of the DC power supply E, and a snubber circuit composed of a series circuit of a resistor R and a capacitor Cs is connected between both ends of the capacitor C1.

The inverter circuit INV is a push-pull type inverter circuit, and has a primary winding N with an intermediate tap.
A choke coil L1 as an inductance element inserted between the positive electrode side of the DC power supply E and the intermediate tap on the primary side of the transformer T;
MOSFETs respectively inserted between one end of the primary windings N11 and N12 of the transformer T1 and the negative electrode of the DC power supply E
Switching elements Q1 and Q2.
That is, the switching elements Q1 and Q2 each constitute a closed loop together with the DC power supply E and the choke coil L1. The switching elements Q1 and Q2 are on / off controlled by control means (not shown). here,
The control means is configured to control both the switching frequency and the duty (on-duty ratio) of the switching elements Q1 and Q2.

In FIG. 1, diodes D01 and D0 connected in anti-parallel to respective switching elements Q1 and Q2 are connected.
02 are the respective MOs constituting the switching elements Q1 and Q2.
FIG. 4 shows parasitic diodes of each SFET. Here, both switching elements Q1 and Q2 have the same specifications. Diodes D11 and D12 are inserted between the drains of the switching elements Q1 and Q2 and the connection point between the resistor R and the capacitor Cs of the snubber circuit, respectively.

The rectifier circuit A is a voltage doubler rectifier circuit, and one end of the secondary winding N2 of the transformer T is connected to a diode D.
21 and D22 in a series circuit.
The other end of the secondary winding N2 is connected to a connection point of the capacitors C21 and C22 in a series circuit of the capacitors C21 and C22. Series circuit of diodes D21 and D22 and capacitors C21 and C22
Are connected in parallel with the series circuit of
An output (smoothing) capacitor C3 is connected between both ends of the series circuit 2, and a load _RL is connected between both ends of the capacitor C3. Therefore, the secondary winding N of the transformer T
2 is full-wave rectified by the diodes D21 and D22, and the voltage smoothed by the series circuit of the capacitors C21 and C22 is further smoothed by the capacitor C3 and applied to both ends of the load _RL . Here, diodes D21 and D22, a capacitor C
21 and C22 have the same specifications.

In this embodiment, a resonance circuit is constituted by the choke coil L1, the leakage inductance of the transformer T, and the capacitor C21 (or C22).

The above-mentioned control means includes two switching elements Q
1, Q2, the switching elements Q1,
A mode in which Q2 does not turn on repeatedly and alternately turns on and off at a frequency near the resonance frequency of the resonance circuit (second mode)
And a mode (first mode) in which when the switching elements Q1 and Q2 are turned on alternately, the duty is made larger than 50% to provide a period in which both switching elements Q1 and Q2 are turned on in an overlapping manner. are doing. In addition, the control means,
The switching frequency and duty of the switching elements Q1 and Q2 are controlled based on the voltage of the DC power supply E detected by input voltage detection means (not shown), the voltage across the load _RL detected by output voltage detection means (not shown), and the like. It has become.

The operation in each mode will be described below.

The on-duty of each of switching elements Q1 and Q2 is set to 50%, and both switching elements Q1 and Q2 are turned on.
In the case of the second mode in which Q2 is turned on and off alternately, the LC resonance state can be controlled by controlling the switching frequency, and the power supplied to the load _RL is adjusted based on the relationship between the switching frequency and the resonance circuit. Therefore, by switching at a frequency near the resonance frequency as in the second mode, a high voltage can be generated at light load or no load. Therefore, if the DC-DC converter of the present embodiment is used as a power supply of a discharge lamp lighting device for lighting an HID lamp, a voltage (a voltage of 2.5 V _L or more) required when starting the HID lamp can be applied. Therefore, the HID lamp can be reliably started.

On the other hand, in the case of the first mode in which the switching elements Q1 and Q2 are alternately turned on, the duty is made larger than 50% to provide a period in which both switching elements Q1 and Q2 are turned on in an overlapping manner. The control signals g1 and g2 of the respective switching elements Q1 and Q2 are
As shown in (a) and (b), energy is stored in the choke coil L1 when both switching elements Q1 and Q2 are on, and when switching element Q1 is on and switching element Q2 is off (or switching element Q1). Is turned off, and the switching element Q2 is turned on), the accumulated energy of the choke coil L1 and the energy from the DC power supply E are superimposed to supply a large power to the load R _L on the secondary side of the transformer T. Here, switching elements Q1,
The longer the period during which Q2 overlaps and turns on, the longer the load R
Large power can be supplied to _L. In short, since the energy accumulated in the choke coil L1 can be adjusted by varying the period during which both the switching elements Q1 and Q2 are turned on in an overlapping manner, the secondary voltage generated across the secondary winding N2 of the transformer T can be adjusted. Can be controlled, so that the output voltage can be controlled. Therefore,
If the DC-DC converter of this embodiment is used as a power supply of a discharge lamp lighting device for lighting an HID lamp, the period from the start of discharge of the HID lamp to stable lighting or the voltage Vin of the DC power supply E is low and large. By performing PWM control with a duty greater than 50% during heavy load such as when power is required, about 2 W _L of power can be supplied to the load R _L. Therefore, the control means detects that the voltage of the DC power supply E is lower than a predetermined threshold value due to a voltage fluctuation or the like based on the detected voltage by the input voltage detection means, and supplies the load _RL with a power larger than the rated power. By operating the inverter circuit INV in the first mode when it is necessary to supply the power, the required power can be obtained. The control means is
When the load _RL is a discharge lamp such as an HID lamp, the switching elements Q1 and Q2 are alternately turned on and off at a duty of 50% during stable lighting.

The voltage of the DC power supply E (hereinafter referred to as input voltage) is Vin, and the current flowing through the choke coil L1 is I
_L , the period during which the control signals g1 and g2 overlap and are on
_ON, when one of the two switching elements Q1, Q2 are on the other hand on to the period is on a T _OFF, the potential Vm of the intermediate tap of the primary of the transformer T, Vm = {1 / (1 -M)} Where M is the switching element Q1 and the switching element Q expressed by M = T _ON / (T _ON + T _OFF ).
2 is the degree of overlap at which the signal turns on.

The number of turns of the primary windings N11 and N12 is N
p, the number of turns of the secondary winding N2 is Ns, and the capacitors C21, C
22 is C ₂ , and the switching frequency of the switching elements Q1 and Q2 is f, the output voltage V of the rectifier circuit A is
Each o and the output power Pout, Vo = 2 (Ns / Np) Vm = 2nVin / (1-M) Pout = (1/2) C 2 Vo 2 × 2f = C 2 f {2nVin /
(1−M)｝ ² , where n is a turns ratio represented by n = Ns / Np.

The rectifier circuit A includes a capacitor C21,
By the capacitance C ₂ of C22 keep constant designed to a small value, since the heavy load charged electric charge of the capacitor C21, C22 are immediately eliminated because of a heavy load capacitor C2
1 and C22 act like a rectifier diode, so that the operation is the same as that of the full-wave rectifier circuit.

In this embodiment, the HI rated power is 35 W
Since the maximum efficiency is desired when the input voltage is 14 V for the purpose of using as a power supply device of a load composed of a D lamp, the duty of each switching element Q1 and Q2 is set to 50%, and the switching elements Q1 and Assuming that the switching frequency f of Q2 is 200 kHz, the capacitances of the capacitors C21, C22, and C3 are determined so that the output power becomes 35 W.

FIG. 3 shows the switching frequency and duty characteristics at which the conversion efficiency is maximized by varying the input voltage under the conditions shown in Table 1 below. FIG. 4 shows a duty characteristic when the voltage is controlled to be constant at 380 V.

[0054]

[Table 1]

In FIG. 3, the horizontal axis is the input voltage (voltage Vin of the DC power supply E), the left vertical axis is the duty and efficiency (output power / input power), and the right vertical axis is the switching frequency. Indicates the duty, indicates the efficiency, and indicates the switching frequency, respectively.

On the other hand, in FIG. 4, the horizontal axis represents the input voltage (voltage Vin of the DC power supply E), the left vertical axis represents the output voltage, and the right vertical axis represents the duty. In FIG. The voltage indicates the duty, and the duty indicates the duty.

FIG. 3 shows that high efficiency is obtained over a wide range of input voltage (8 V to 18 V) by controlling the duty and the switching frequency, respectively. FIG. 4 shows that by controlling the duty in a range larger than 50%, an output voltage of a high voltage (380 V) can be obtained over a wide range of the input voltage (8 V to 18 V). Therefore, H
When starting the ID lamp, a high voltage can be reliably supplied. Not only at the time of starting the HID lamp, but also at the time of dimming the discharge lamp, the switching frequency may be appropriately shifted from the resonance frequency, and the voltage exceeding the re-ignition voltage may be continuously applied so that the lighting is maintained.

Thus, in the present embodiment, a high voltage required at the time of starting a discharge lamp such as an HID lamp can be obtained over a wide range of the input voltage due to the resonance action of the resonance circuit at a light load and a heavy load. In such a case, a large power can be obtained by an operation exhibiting a step-up chopper operation, and the efficiency is also increased because the duty is set to 50% during steady lighting.
In this embodiment, the capacitor C2 of the rectifier circuit A is used.
Since C1 and C22 also serve as capacitors of the resonance circuit, the number of components can be reduced as compared with a case where a resonance capacitor is separately prepared, and cost reduction can be achieved.

Further, since the switching element Q1 and Q2 have the first mode in which the switching element Q1 and the switching element Q2 are turned on, the use efficiency of the transformer T and the switching elements Q1 and Q2 can be increased, and the number of parts can be reduced. It can be used as a power supply device for a load such as an HID lamp that has a large change in load state, and improvement in reliability can be expected. Further, at a light load, a high voltage can be supplied by utilizing the resonance action. Therefore, it is not necessary to increase the turns ratio of the transformer T so much, and the size of the transformer T can be reduced.

[0060] In the present embodiment, since the capacity C ₂ of the capacitor C21, C22 connected in series is the same, positive and negative direction of the peak value of the current flowing through the capacitor C21, C22 flows through the secondary winding N2 of the transformer T In the half cycle, the output voltage ripple is reduced.

FIG. 5 shows an example of the operation waveform of each part when the duty of the control signals g1 and g2 of both switching elements Q1 and Q2 is set to 50% under the conditions shown in Table 1 above. Voltage (input voltage) Vin across E
(B) shows the control signal g1 of the switching element Q1;
(C) shows the control signal g2 of the switching element Q2,
(D) is a voltage V _TP1 across the primary winding N11 of the transformer T.
(E) is the voltage V across the primary winding N12 of the transformer T.
_TP2 , (f) the voltage V _TS across the secondary winding N2 of the transformer T, and (g) the voltage V _TS across the capacitor C21.
_C21 , (h) is the voltage V _C22 across the capacitor C22,
(I) shows the output voltage Vo across the load _RL .

(Embodiment 2) The basic configuration of a DC-DC converter of this embodiment is substantially the same as that of Embodiment 1, and as shown in FIG. 6, in a rectifier circuit A, capacitors C21 and C22 connected in series. Each diode D2
3, D24 is connected in parallel. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Here, also in the present embodiment, the control means for turning on and off the switching elements Q1 and Q2 is the same as that in the first embodiment.
Has the same first mode and second mode.

The rectifier circuit A according to the present embodiment functions as a voltage doubler rectifier circuit similar to that of the first embodiment when the load is light, and the diodes D23 and D24 are connected in parallel to the capacitors C21 and C22 respectively when the load is heavy. It functions more reliably as a full-wave rectifier circuit than the first embodiment. In the present embodiment, the number of components is increased as compared with the first embodiment, but it is possible to reliably supply a necessary voltage to the load _{RL under} heavy load.

(Embodiment 3) The basic configuration of a DC-DC converter of this embodiment is substantially the same as that of Embodiment 1, and as shown in FIG. 7, a rectifier circuit A is formed by a full-wave rectifier circuit composed of a diode bridge. A resonance capacitor C is connected between the output terminals of the rectifier circuit A, and a smoothing choke coil L2 is connected between the high-potential end of the capacitor C and the load _RL.
There is a feature in the point that is inserted. Here, the capacitor C, the choke coil L2, and the capacitor C3 constitute a capacitor input type smoothing circuit. The capacitor C also serves as a resonance capacitor, and the smoothing choke coil L2
Functions as a high-frequency cut filter so that the capacitor C can form a resonance circuit with the choke coil L1 on the primary side of the transformer T and the transformer T at a light load, so that the resonance state of the resonance circuit can be maintained. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Also in this embodiment, the control means for turning on and off the switching elements Q1 and Q2 is the same as that in the first embodiment
Has the same first mode and second mode.

In the present embodiment, the number of components is increased as compared with the first embodiment, but it is possible to reliably supply a necessary voltage to the load _{RL under} heavy load. The DC-DC converter according to the present embodiment is suitable for a case where a very high voltage is not required at the time of starting depending on a load condition, for example, a type of a discharge lamp.

(Embodiment 4) The basic configuration of a DC-DC converter of this embodiment is substantially the same as that of Embodiment 3, and a resonance capacitor C is connected to a secondary winding of a transformer T as shown in FIG. The only difference is that it is connected between both ends of N2. Also in this embodiment, the smoothing choke coil L
2 functions as a high-frequency cut filter so that the capacitor C can form a resonance circuit with the choke coil L1 on the primary side of the transformer T and the transformer T at a light load, so that the resonance state of the resonance circuit can be maintained. In addition,
The same components as those in the third embodiment are denoted by the same reference numerals, and description thereof is omitted. Here, also in the present embodiment, the control means for turning on and off the switching elements Q1 and Q2 has the same first mode and second mode as in the first embodiment.

(Embodiment 5) The basic configuration of a DC-DC converter according to the present embodiment is substantially the same as that of Embodiment 1, and two secondary windings are provided on the secondary side of a transformer T as shown in FIG. N21 and N22, and capacitors C and C for resonance are inserted between both ends of each of the secondary windings N21 and N22. It is characterized in that a series circuit with the loads _RL and _RL is connected. Here, each capacitor C provided on the secondary side of the transformer T may be connected between both ends of each of the secondary windings N21 and N22 as shown by a broken line in FIG. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Here, also in the present embodiment, the control means for turning on and off the switching elements Q1 and Q2 is the same as the first mode and the second mode as in the first embodiment.
Mode.

In the present embodiment, when the load is light, the resonance action occurs and the rectification is performed in each of the positive and negative half cycles of the secondary voltage of the transformer T, so that a high voltage can be applied to each load _RL .

Thus, in the present embodiment, two loads R _L
Power can be supplied to the discharge lamps at the same time, so-called parallel lighting in which two discharge lamps are simultaneously turned on is possible.
Even when the number of secondary windings is increased to a plurality (three or more), power can be simultaneously supplied to a plurality of loads.

(Embodiment 6) DC-D of each of the above embodiments
In the C converter, a push-pull type inverter circuit is used as the inverter circuit INV. However, in the present embodiment, a full bridge type inverter circuit is used as the inverter circuit. That is, the inverter circuit according to the present embodiment includes a series circuit of switching elements Q11 and Q12 each including a pair of MOSFETs, and a pair of MOSFs.
A series circuit of switching elements Q13 and Q14 made of ET is connected between both ends of a series circuit of DC power supply E and choke coil L1, and a connection point of switching elements Q11 and Q12 in one arm and the other arm. , The primary winding N1 of the transformer T is connected to the connection point of the switching elements Q13 and Q14. The rectifier circuit described in any of the first to fifth embodiments is connected between both ends of the secondary winding N2 of the transformer T, and a load is connected between the output terminals of the rectifier circuit. In short, FIG.
The portions shown by broken lines in the first to fifth embodiments
In each of the circuit diagrams (FIGS. 1, 6 to 9), the circuits enclosed by broken lines may be connected. In FIG. 10, diodes D011 to D014 connected in anti-parallel to switching elements Q11 to Q14 are connected to switching elements Q1 to Q14, respectively.
FIG. 2 shows parasitic diodes of respective MOSFETs constituting 1 to Q14. Here, the switching elements Q11 to Q14 having the same specifications are used.

In this embodiment, the switching element Q1
The control mode of the control means for controlling the on / off of 1 to Q14 will be described. The control means is configured to control both the switching frequency and the duty, as in the first embodiment.

When the load is light or no load, the control means switches the switching elements Q11 and Q14 (or Q12 and Q1) at the diagonal positions of the four switching elements.
3) so that the switching elements Q11 to Q14 are turned on simultaneously and the switching elements Q11 and Q12 (or Q13 and Q14) connected in series are alternately turned off.
Control. Therefore, an alternating voltage is output between both ends of the secondary winding N2 of the transformer T.

The control means controls the on / off of each of the switching elements Q11 to Q14 at the time of heavy load by a control signal as shown in FIG. 11 to FIG.
Here, in each figure, (a) is a control signal to the gate of switching element Q11, (b) is a control signal to the gate of switching element Q12, and (c) is switching element Q13.
Control signal to the gate of the switching element Q1.
Control signals to the gates No. 4 are shown.

The example shown in FIG. 11 is an example in which a period in which four switching elements Q11 to Q14 are turned on in an overlapping manner is provided, and four switching elements Q11 to Q14 are provided.
Are turned on repeatedly, a current flows through the choke coil L1 along the path A and the path B shown by the dashed line in FIG. That is, current flows through the path of DC power supply E → choke coil L1 → switching element Q11 → switching element Q12 → DC power supply E, and the path of DC power supply E → choke coil L1 → switching element Q13 → switching element Q14 → DC power supply E. Because it flows, choke coil L1
The current flowing through each arm is diverted to each arm, and the load on Q11 to Q14 of each switching element can be substantially equalized. In the present embodiment, since a full-bridge inverter circuit is configured, it is suitable for a case where the output load is larger than that of a push-pull inverter circuit. However, the same effects as those of the first embodiment can be obtained.

The example shown in FIG. 12 is a mode in which a period in which the switching elements Q11 and Q12 of one arm overlap and are turned on is provided (simultaneous on-mode), and the switching elements Q11 and Q12 overlap. When the switch is turned on, a current flows through a path of DC power supply E → choke coil L1 → switching element Q11 → switching element Q12 → DC power supply E.

The example shown in FIG. 13 is a mode in which a period in which the switching elements Q13 and Q14 of the other arm overlap and are turned on is provided (two simultaneous ON mode), and the switching elements Q13 and Q14 overlap. When the switch is turned on, a current flows through the path of the DC power supply E → the choke coil L1 → the switching element Q13 → the switching element Q14 → the DC power supply E.

In the example shown in FIG. 14, a period in which the switching elements Q11 and Q12 of one arm overlap and turns on and a period in which the switching elements Q13 and Q14 of the other arm overlap and turn on alternately. In the provided mode (sequential switching on mode), the switching element Q
When the power supply 11 and the power supply Q12 are turned on repeatedly, the DC power supply E →
A current flows through the path of the choke coil L1, the switching element Q11, the switching element Q12, and the DC power supply E,
When the switching elements Q13 and Q14 are turned on in an overlapping manner, a current flows through the path of the DC power supply E → the choke coil L1 → the switching element Q13 → the switching element Q14 → the DC power supply E. The burden on Q11 to Q14 can be substantially equalized.

The example shown in FIG. 15 is a mode in which three switching elements Q11, Q12, and Q13 are provided with a period in which they are turned on in an overlapped manner (three simultaneous ON mode), and the three switching elements Q11, Q12, When Q13 is ON repeatedly, a current flows through the choke coil L1 through the path A and the path D indicated by the alternate long and short dash line in FIG. That is,
DC power supply E → choke coil L1 → switching element Q
11 → switching element Q12 → DC power supply E, and DC power supply E → choke coil L1 → switching element Q13 → primary winding N1 of transformer T → switching element Q12 → DC power supply E ,
The current flowing through the choke coil L1 is divided into two paths A and D.

In the example shown in FIG. 16, a period in which three switching elements Q11, Q12, and Q13 overlap and turns on, and a period in which three switching elements Q11, Q13, and Q14 overlap and turn on alternately. Provided mode (sequential switching on mode), in which three switching elements Q
In the case where 11, Q12 and Q13 are turned on repeatedly, FIG.
During 0, a current flows through the choke coil L1 through a path A and a path D indicated by a chain line. That is, the path of the DC power supply E → the choke coil L1 → the switching element Q11 → the switching element Q12 → the DC power supply E, and the DC power supply E → the choke coil L1 → the switching element Q13 → the transformer T
Primary winding N1 → switching element Q12 → DC power supply E
Since the current flows through the path d, the current flowing through the choke coil L1 is divided into the two paths a and d. Also, 3
When the two switching elements Q11, Q13, and Q14 are turned on in an overlapping manner, a current flows through the choke coil L1 through the path d and the path c shown by the alternate long and short dash line in FIG. That is, the path of the DC power supply E → the choke coil L1 → the switching element Q13 → the primary winding N1 of the transformer T → the switching element Q12 → the DC power supply E, and the DC power supply E → the choke coil L1 → the switching element Q11 → the primary of the transformer T A current flows through the winding N1, the switching element Q14, and the path C of the DC power supply E. Therefore, the load on each of the switching elements Q11 to Q14 can be reduced.

(Embodiment 7) The basic configuration of the power supply device of the present embodiment is substantially the same as that of Embodiment 1, except for the circuit configuration on the secondary side of the transformer T. As shown in FIG. A resonance capacitor C is connected between both ends of the secondary winding N2, and a series circuit of a DC cut capacitor Cr and a load _RL is connected between both ends of the capacitor C. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the switching element Q
1 and Q2 are controlled on / off by control means (not shown), but the control means in this embodiment also controls on / off of both switching elements Q1 and Q2 as in the first embodiment.

When a discharge lamp such as an HID lamp is used as the load R _L , the control means controls the switching frequency of the switching elements Q 1 and Q 2 at the time of no load or light load to boost the voltage by resonance. The applied voltage is applied to the load R _L, and at the time of heavy load after the start of discharge, the control means alternately turns on and off the switching elements Q1 and Q2 so that a period in which both switching elements Q1 and Q2 overlap and are turned on is provided. By turning on and off, necessary power can be supplied.

As another configuration example, a separate resonance circuit including a capacitor Cr is formed to prevent the discharge lamp from becoming lower than the re-ignition voltage when the polarity of the power supply is switched or when the voltage value of the power supply changes suddenly. Thus, a stable lighting state of the discharge lamp can be maintained.

(Embodiment 8) The basic configuration of a power supply device of this embodiment is substantially the same as that of Embodiment 7, except that a resonance capacitor C is provided on the primary side of the transformer T as shown in FIG. There is a feature. In the example shown in FIG. 18, diodes D04 and D0 are connected to switching elements Q1 and Q2, respectively.
3 are connected in series.
03 is connected in the opposite direction to the parasitic diodes D01 and D02 of the switching elements Q1 and Q2, and can prevent a return current from flowing through the parasitic diodes D01 and D02. Since the basic operation is the same as that of the first embodiment, the same reference numerals are given to the same components as those of the first embodiment, and the description will be omitted.

(Embodiment 9) In the present embodiment, as shown in FIG.
This is a dual circuit employing the current source Is and connecting the capacitor Ci in parallel with the current source Is. In the present embodiment, the current source I
s is connected to an intermediate tap on the primary side of the transformer T, and switching elements Q1 and Q2 each composed of a MOSFET are provided between one end of each of the primary windings N11 and N12 of the transformer T1 and the other end of the current generator Is. Is connected. The switching elements Q1 and Q2 are on / off controlled by control means (not shown). Here, the control means is configured to be able to control both the switching frequency and the duty (on-duty ratio) of the switching elements Q1 and Q2.

In this embodiment, on the secondary winding N2 side of the transformer T, a series circuit of the diode D21 and the choke coil Li1, a series circuit of the diode D23 and the choke coil Li2, and a smoothing capacitor C3
Are connected in parallel, one end of the secondary winding N2 is connected to a connection point between the diode D21 and the choke coil Li1, and the other end of the secondary winding N2 is connected to a connection point between the diode D23 and the choke coil Li2. It is connected. A load _RL is connected to both ends of the capacitor C3. In addition,
A series current rectifier circuit is configured by a series circuit of the diode D21 and the choke coil Li1 and a series circuit of the diode D23 and the choke coil Li2. When a current flowing through the secondary winding N2 of the transformer T is i, Diode D
The combined current of the current flowing through the diode 21 and the current flowing through the diode D23 is 2i.

In the present embodiment, the control means sets the switching elements Q1 and Q2 to 5
A period is provided in which the switching elements Q1 and Q2 are turned off in an overlapping manner by alternately turning on and off with a duty of less than 0% (first mode). Here, when both the switching elements Q1 and Q2 are off, the capacitor Ci is charged by the current from the current source Is, and the voltage across the capacitor Ci becomes a high voltage.
When one of Q1 and Q2 is turned on, a high voltage is generated in the secondary winding N2 of the transformer T, so that a high voltage is applied to both ends of the load _RL . In this case, a higher voltage can be applied to the load _RL by bringing the switching frequency closer to the resonance frequency of the resonance circuit formed by the capacitor Ci and the choke coil Li1 or Li2 (by causing half-wave resonance). . In addition, even when both the switching elements Q1 and Q2 are turned off, a current flows through the choke coils Li1 and Li2.

On the other hand, the control means controls the switching elements Q1 and Q2 in the first mode in which the duty of the switching elements Q1 and Q2 is set to 50% and the switching elements Q1 and Q2 are turned on and off alternately without a period in which the switching elements are turned on. Thus, the load power can be increased at a low voltage. Therefore, it can be used as a low-voltage / high-current power supply device.

(Embodiment 10) The basic configuration of this embodiment is substantially the same as that of Embodiment 9, and as shown in FIG. 20, a leakage transformer is adopted as the transformer T, and a diode is used instead of the choke coils Li1 and Li2. D22, D
24 is different. That is, in the present embodiment, the diodes D21 to D24 form a full-wave rectifier circuit. Note that the same components as those in the ninth embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the switching element Q1 and the transformer T and the switching element Q2 and the transformer T constitute a flyback type converter at no load and light load, respectively, and the operation phase is inverted (the phase is 180).
On / off of the switching elements Q1 and Q2 is controlled so as to perform a pair of flyback converter operations.

In the present embodiment, since a gap is provided in the transformer T, the transformer T
And the stray capacitance component such as windings can generate an output voltage equal to or higher than the turns ratio of the transformer T.

The control of the switching elements Q1 and Q2 under no load and light load requires little power as the duty of the switching elements Q1 and Q2 is less than 50% and the duty is small. Therefore, it is necessary to lower the switching frequency. Accordingly, a high voltage can be efficiently obtained with low power.

At the time of heavy load, each switching element Q1, Q
2 is alternately turned on and off at a duty of 50% to perform a two-push push-pull inverter operation, thereby obtaining a large current at a low voltage.

FIG. 21 shows the secondary winding N2 of the transformer T.
(A) shows a comparatively low switching frequency and an on-duty of 50.
%, And FIG. 7B shows a voltage waveform when the switching frequency is relatively high and the on-duty is 50%. Here, assuming that the peak value of the latter voltage is V _S2 , the peak value V _S1 of the former voltage is twice or more the value of V _S2 . FIG. 22 schematically shows the relationship between the output current and the output voltage and the operation mode.

(Embodiment 11) DC-DC of this embodiment
The converter has the circuit configuration shown in FIG. 23 and has the same configuration as that of the first embodiment. The same components as those of the first embodiment are denoted by the same reference numerals.

In the present embodiment, when no load or light load is applied, the switching element Q1 and the transformer T constitute a flyback type converter and the switching element Q1
2 and a transformer T to form a forward converter, and control the on / off of the switching elements Q1 and Q2 so that the operation becomes an operation in which the operation phase is inverted (the phase is different by 180 degrees). .

Under no load and light load, a high voltage is obtained by operating the switching element Q1 and the transformer T so that a flyback converter is constituted. In this case, lower the switching frequency and set the duty to 50%.
With the control made less than the above, a high voltage of a small power can be obtained with high efficiency.

At the time of heavy load, each switching element Q1, Q
The duty of 2 is made larger than 50%, and both switching elements Q1 and Q2 are alternately turned on and off, and a period in which they are turned on in an overlapping manner is provided to operate the chopper and to operate the two-push push-pull type inverter to obtain a large current. Therefore, large power can be supplied.

[0099]

According to a first aspect of the present invention, there is provided a DC voltage source, and at least two switching elements each forming a closed loop together with the DC voltage source and an inductance element, and converting an output voltage of the DC voltage source into an AC output. An inverter circuit that outputs to the secondary winding side of the transformer
A resonance capacitor forming a resonance circuit with the transformer and the inductance element, wherein the inverter circuit has a period in which the at least two switching elements are turned on in an overlapping manner and energy is stored in the inductance element; A first mode having a period in which one of the at least two switching elements is turned off and the energy stored in the inductance element is superimposed on the energy of the DC voltage source and discharged to the primary winding of the transformer; A second mode in which at least two switching elements do not turn on in an overlapping manner and are alternately turned on and off at a frequency near the resonance frequency of the resonance circuit, and the inverter circuit operates in the first mode. Means that the at least two switching elements are switching of a boost chopper Therefore, by adjusting the period during which the at least two switching elements are overlapped and on, the secondary voltage of the transformer can be controlled and a large power can be obtained. When operating in the second mode, the at least two switching elements do not turn on in an overlapping manner and are alternately turned on and off at a frequency near the resonance frequency of the resonance circuit.
Even if the value of the input voltage changes, the output voltage and output power can be controlled by adjusting the switching frequency and on-duty of the switching element, and a high voltage can be obtained, and the output can be obtained without changing the capacitor constant. Since the voltage and the output power can be controlled, the applicable range of the input voltage and the control range of the output voltage and the output power can be widened, high efficiency and small size can be achieved, and the load state is large like the HID lamp. In the case of a changing load, by operating in the first mode at the time of heavy load and operating in the second mode at the time of light load, it can be used as a power supply for a load such as an HID lamp whose load state changes greatly. This has the effect.

According to a second aspect of the present invention, there is provided a DC voltage source, and at least two switching elements each forming a closed loop together with the DC voltage source and the inductance element, and converting an output voltage of the DC voltage source into an AC output. An inverter circuit that outputs to the secondary winding side of the transformer, a resonance capacitor that forms a resonance circuit with the transformer and the inductance element, and an output voltage of the inverter circuit that is converted into a predetermined DC voltage and supplied to a load. A rectifier circuit, wherein the inverter circuit is configured such that the at least two switching elements are turned on in an overlapping manner and energy is accumulated in the inductance element, and one of the at least two switching elements is turned off. The stored energy of the inductance element is superimposed on the DC voltage source A first mode having a period of discharging to the primary winding of the transformer, and a second mode in which the at least two switching elements are not turned on repeatedly and are alternately turned on and off at a frequency near the resonance frequency of the resonance circuit. And when the inverter circuit operates in the first mode, the at least two switching elements function as switching elements of the at least two switching element boosting choppers, so that the at least two switching elements are ON repeatedly. By adjusting the period, the secondary voltage of the transformer can be controlled and a large power can be obtained. When the inverter circuit operates in the second mode, the at least two switching elements overlap. Since it is turned on and off alternately at a frequency near the resonance frequency of the resonance circuit without turning on, the value of the input voltage changes. Even by adjusting the switching frequency and on-duty of the switching element, it is possible to control the output voltage and output power and obtain a high voltage, and control the output voltage and output power without changing the capacitor constant. Therefore, the application range of the input voltage, the output voltage, and the control range of the output power are wide, and high efficiency and miniaturization can be achieved. In the case of a load such as an HID lamp whose load state greatly changes, By operating in the first mode at the time of heavy load and operating in the second mode at the time of light load, there is an effect that it can be used as a power supply device of a load such as an HID lamp whose load state changes greatly.

A third aspect of the present invention, according to the first aspect, further comprises control means for controlling on / off of each of the switching elements, wherein the control means controls a voltage of the DC voltage source to be lower than a predetermined threshold value. When the inverter circuit is operated in the first mode when it is necessary to supply a low power to the load and the power is larger than the rated power, the inverter circuit operates even when the voltage of the DC voltage source is lower than a predetermined threshold. There is an effect that electric power can be supplied.

According to a fourth aspect of the present invention, in the discharge lamp according to the first aspect of the present invention, the load requires a larger amount of power in a transition period from the start of the discharge to the stable lighting as compared with the stable lighting. Control means for controlling the on / off of the element, wherein the control means operates the inverter circuit in the first mode during the transition period, so that even if the load is, for example, an HID lamp, from the start of discharge to stable lighting. There is an effect that it is possible to supply a large amount of power required during the transition period.

A fifth aspect of the present invention, in the first aspect of the present invention, further comprises control means for controlling the on / off of each of the switching elements, wherein the control means controls the inverter circuit to operate at the time of light load or no load. In this mode, the required high voltage can be supplied to the load at light load or no load.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the load is a discharge lamp, and the load includes a control means for controlling on / off of each of the switching elements. Since the inverter circuit is operated in the second mode at the time of starting or dimming, it is possible to obtain the required output voltage and output power at the time of starting discharging or dimming of the discharge lamp.

The invention of claim 7 is the invention of claim 2, further comprising control means for controlling on / off of each of the switching elements, wherein the control means makes the voltage of the DC voltage source lower than a predetermined threshold value. When the inverter circuit is operated in the first mode when it is necessary to supply a low power to the load and the power is larger than the rated power, the inverter circuit operates even when the voltage of the DC voltage source is lower than a predetermined threshold. There is an effect that electric power can be supplied.

According to an eighth aspect of the present invention, in the discharge lamp according to the second aspect of the present invention, the discharge lamp requires a larger amount of power in a transition period from the start of discharging to the stable lighting as compared with the stable lighting. Control means for controlling on / off of the element, wherein the control means operates the inverter circuit in the first mode during the transition period, so that even when the load is, for example, an HID lamp, the lamp is changed to a stable lighting after the start of discharge. There is an effect that it is possible to supply a large amount of electric power required during the transition period.

In a ninth aspect of the present invention, in accordance with the second aspect of the present invention, there is provided a control means for controlling on / off of each of the switching elements, wherein the control means controls the inverter circuit to the second state at light load or no load. In this mode, the required high voltage can be supplied to the load at light load or no load.

According to a tenth aspect of the present invention, in the second aspect of the present invention, the load is a discharge lamp, further comprising control means for controlling ON / OFF of each of the switching elements, wherein the control means discharges the discharge lamp. Since the inverter circuit is operated in the second mode at the time of starting or dimming, it is possible to obtain the required output voltage and output power at the time of starting discharging or dimming of the discharge lamp.

The invention of claim 18 is the invention of claim 2, wherein the rectifier circuit is a voltage doubler rectifier circuit connected between both ends of a secondary winding of the transformer, wherein the capacitor of the voltage doubler rectifier circuit is Is also used as the resonance capacitor, so that there is no need to separately provide the resonance capacitor, and the number of parts can be reduced.

According to a nineteenth aspect of the present invention, in the invention of the eighteenth aspect, diodes are connected in anti-parallel between both ends of each capacitor of the voltage doubler rectifier circuit. There is an effect that the full-wave rectification operation is reliably performed at the time of load.

According to a twentieth aspect, in the second aspect, the rectifier circuit is a full-wave rectifier circuit comprising a diode bridge connected between both ends of a secondary winding of the transformer. A capacitor input type smoothing circuit connected between the output terminals of the rectifier circuit is provided.Since the capacitor of the capacitor input type smoothing circuit also serves as the resonance capacitor, the AC component is removed by the capacitor input type smoothing circuit. In addition, since the capacitor of the capacitor input type smoothing circuit also serves as the resonance capacitor, there is no need to separately provide a resonance capacitor, and the number of components can be reduced. .

According to a twenty-first aspect, in the second aspect, the rectifier circuit is a full-wave rectifier circuit including a diode bridge connected between both ends of a secondary winding of the transformer. A choke coil connected between the output terminals of the rectifier circuit and a series circuit of a smoothing capacitor, wherein the resonance capacitor is connected between both ends of the secondary winding on the input side of the full-wave rectifier circuit. Therefore, there is an effect that an AC component can be removed by a series circuit of a choke coil connected between the output terminals of the full-wave rectifier circuit and a smoothing capacitor.

According to a twenty-third aspect of the present invention, in the first to fifteenth aspects, the transformer has a plurality of secondary windings, and the resonance capacitor is provided for each secondary winding. Therefore, there is an effect that power can be supplied to a plurality of loads simultaneously.

According to a twenty-fourth aspect of the present invention, in the first to fifteenth aspects, the transformer has two secondary windings, and a rectifying diode is provided between both ends of each secondary winding. Since a load is inserted and the resonance capacitor is inserted between both ends of each secondary winding, there is an effect that power can be simultaneously supplied to a plurality of loads.

According to a twenty-sixth aspect of the present invention, there is provided a DC voltage source, and two switching elements each forming a closed loop together with the DC voltage source and an inductance element. An inverter circuit that outputs to the secondary winding side, a resonance capacitor that forms a resonance circuit with the transformer and the inductance element, and converts an output voltage of the inverter circuit into a predetermined DC voltage and supplies the DC voltage to a load A rectifier circuit, wherein the inverter circuit alternately turns on and off both switching elements at a duty exceeding 50% and stores energy in the inductance element during a period in which both switching elements are turned on in an overlapping manner; One turns off and the stored energy in the inductance element A first mode superimposed on the energy of the source and emitted to the primary winding of the transformer, a flyback converter is constituted by one switching element and the transformer, and a forward converter is constituted by the other switching element and the transformer. And a second mode for controlling the switching element so as to constitute the second mode. When the second mode is operated at no load and at light load, a high voltage of small power can be obtained with high efficiency. Also, there is an effect that large power can be supplied by operating in the first mode at the time of heavy load.

According to a twenty-seventh aspect of the present invention, a DC current source, a capacitor connected in parallel to the DC current source, and two switching elements forming a closed loop together with the DC current source via a primary winding of a transformer are provided. An inverter circuit that converts the output current of the DC current source into an AC output and supplies the AC current to a load on a secondary winding side of a transformer; and an inductance element that forms a resonance circuit with the capacitor. , Each switching element is 50
A first mode in which a period in which the switching element is alternately turned on and off with a duty of less than% and overlapped off is provided, and each switching element is alternately turned on and off at a frequency near the resonance frequency of the resonance circuit with a duty of 50%. A second mode, wherein the first mode is used when there is no load and when the load is light.
By operating in the second mode, a required high voltage can be applied to the load, and by operating in the second mode under heavy load, the load power can be increased at a low voltage. .

According to a twenty-eighth aspect of the present invention, there is provided a DC current source, a capacitor connected in parallel to the DC current source, and two switching elements forming a closed loop together with the DC current source via a primary winding of a transformer. An inverter circuit that converts the output current of the DC current source into an AC output and outputs the AC current to the secondary winding side of a transformer; and an inductance element that forms a resonance circuit with the capacitor. A first mode in which each switching element operates as a flyback type converter together with a primary winding connected in series, and a second mode in which each switching element operates as a push-pull inverter in which each switching element is turned on and off at a duty of 50%. Operating in the first mode at no load and at light load. Ri, high voltage low power can be obtained efficiently, by operating in the second mode to the heavy load, there is an effect that it is possible to obtain a high current low voltage.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is a characteristic explanatory diagram of the above.

FIG. 4 is a characteristic explanatory diagram of the above.

FIG. 5 is an operation explanatory view of the above.

FIG. 6 is a circuit diagram showing a second embodiment.

FIG. 7 is a circuit diagram showing a third embodiment.

FIG. 8 is a circuit diagram showing a fourth embodiment.

FIG. 9 is a circuit diagram showing a fifth embodiment.

FIG. 10 is a circuit diagram showing a sixth embodiment.

FIG. 11 is an operation explanatory diagram of the above.

FIG. 12 is an operation explanatory view of the above.

FIG. 13 is an explanatory diagram of the operation of the above.

FIG. 14 is an operation explanatory view of the above.

FIG. 15 is an explanatory diagram of the operation of the above.

FIG. 16 is an operation explanatory view of the above.

FIG. 17 is a circuit diagram showing a seventh embodiment.

FIG. 18 is a circuit diagram showing an eighth embodiment.

FIG. 19 is a circuit diagram showing a ninth embodiment;

FIG. 20 is a circuit diagram showing a tenth embodiment.

FIG. 21 is an explanatory diagram of the above operation.

FIG. 22 is an explanatory diagram of the above operation.

FIG. 23 is a circuit diagram showing an eleventh embodiment.

FIG. 24 is a circuit diagram showing a first conventional example.

FIG. 25 is a circuit diagram showing a third conventional example.

FIG. 26 is a circuit diagram showing a fourth conventional example.

FIG. 27 is a circuit diagram showing a conventional example 5;

[Explanation of symbols]

A Rectifier circuit E DC power supply INV Inverter circuit N11, N12 Primary winding N2 Secondary winding L1 Choke coil Q1, Q2 Switching element R _L load T Transformer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K072 AA11 AC18 AC20 BB09 CA16 GA03 GB14 GC04 HA05 HA06 HA10 5H007 BB03 CA02 CB05 CB06 CB25 CC32 5H730 AA15 AS11 BB25 BB27 BB61 CC10 DD04 EE04 EE06 EE07 EE08 FE07 FD08

Claims (28)

[Claims] 1. A secondary winding of a transformer, comprising: a DC voltage source; and at least two switching elements each forming a closed loop together with the DC voltage source and an inductance element, converting an output voltage of the DC voltage source into an AC output. And an inverter circuit for outputting to the line side, and a resonance capacitor forming a resonance circuit with the transformer and the inductance element. The inverter circuit is configured such that the at least two switching elements are turned on in an overlapping manner and the inductance is reduced. A period during which energy is stored in the element and a period during which one of the at least two switching elements is turned off and the stored energy of the inductance element is superimposed on the energy of the DC voltage source and discharged to the primary winding of the transformer. A first mode having at least two switches. A second mode in which the switching elements are alternately turned on and off at a frequency near the resonance frequency of the resonance circuit without being turned on in an overlapping manner.
C converter. 2. A secondary winding of a transformer, comprising: a DC voltage source; and at least two switching elements each forming a closed loop together with the DC voltage source and an inductance element, converting an output voltage of the DC voltage source into an AC output. An inverter circuit that outputs to the line side, a resonance capacitor that forms a resonance circuit with the transformer and the inductance element, and a rectifier circuit that converts an output voltage of the inverter circuit into a predetermined DC voltage and supplies the DC voltage to a load. Prepare,
The inverter circuit includes a period in which the at least two switching elements are turned on in an overlapping manner and energy is stored in the inductance element, and a state in which one of the at least two switching elements is turned off and the stored energy of the inductance element is reduced. A first mode having a period in which the energy is superimposed on the energy of the DC voltage source and discharged to a primary winding of the transformer; A second mode that is alternately turned on and off at a frequency. 3. A control means for controlling ON / OFF of each of the switching elements, wherein the control means supplies a power whose voltage of the DC voltage source is lower than a predetermined threshold value and which is higher than a rated power to a load. The DC-DC converter according to claim 1, wherein the inverter circuit is operated in the first mode when necessary. 4. A discharge lamp that requires a larger power than during stable lighting during a transition period from a start of discharging to a stable lighting of the load, further comprising control means for controlling on / off of each of the switching elements. 2. The DC-DC converter according to claim 1, wherein the control unit operates the inverter circuit in the first mode during the transition period. 5. A control device for controlling ON / OFF of each of the switching elements, wherein the control device operates the inverter circuit in the second mode at light load or no load. DC-DC according to 1.
converter. 6. The load lamp is a discharge lamp, and further includes control means for controlling on / off of each of the switching elements. The control means controls the inverter circuit when the discharge lamp starts discharging or when dimming is performed. 2. The DC-DC converter according to claim 1, wherein the DC-DC converter is operated in two modes. 7. A control unit for controlling ON / OFF of each of the switching elements, wherein the control unit supplies power greater than a rated power to a load when a voltage of the DC voltage source is lower than a predetermined threshold value. 3. The DC-DC converter according to claim 2, wherein the inverter circuit is operated in the first mode when necessary. 8. A discharge lamp which requires a larger power than during stable lighting during a transition period from a start of discharging to a stable lighting of the load, further comprising control means for controlling on / off of each switching element. The DC-DC converter according to claim 2, wherein the control means operates the inverter circuit in the first mode during the transition period. 9. A control device for controlling on / off of each of the switching elements, wherein the control device operates the inverter circuit in the second mode at light load or no load. DC-DC according to 2
converter. 10. The load is a discharge lamp, comprising control means for controlling on / off of each of the switching elements,
3. The DC-DC converter according to claim 2, wherein the control unit operates the inverter circuit in the second mode at the time of starting discharge or dimming of the discharge lamp. 4. 11. The DC-DC converter according to claim 1, wherein the inverter circuit has a choke coil as the inductance element on an input side. 12. The DC-to-DC converter according to claim 1, wherein said inverter circuit is a push-pull type inverter circuit having a choke coil as said inductance element on an input side.
DC converter. 13. The DC-DC converter according to claim 1, wherein the inverter circuit is a full-bridge inverter circuit having a choke coil as the inductance element on an input side. . 14. The inverter circuit is a full-bridge type inverter circuit having a choke coil as the inductance element on the input side, and the first mode is configured such that at least two switching elements are turned on in an overlapping manner. Four simultaneous ON modes in which four switching elements of a circuit are turned on in duplicate, two simultaneous ON modes in which two switching elements of one arm are turned on in duplicate, and two switching elements of one arm are duplicated A mode selected from a sequential switching-on mode in which a period in which the switching element is turned on and a period in which the two switching elements of the other arm are turned on are alternately provided. The DC-DC converter according to claim 10. 15. The inverter circuit according to claim 1, wherein the inverter circuit is a full-bridge inverter circuit having a choke coil as the inductance element on an input side. Two simultaneous ON mode in which two switching elements of one arm are turned on in an overlapping manner, a period in which two switching elements of one arm are turned on in an overlapping manner, and two switching elements of the other arm are turned on in an overlapping manner. 11. A mode selected from a sequential switching on mode in which the switching periods are provided alternately and a three simultaneous on mode in which three switching elements are turned on in an overlapped manner.
The DC-DC converter according to any one of the above. 16. The DC-DC converter according to claim 1, wherein the resonance capacitor is provided on a primary side of the transformer. 17. The DC-DC converter according to claim 1, wherein the resonance capacitor is provided on a secondary side of the transformer. 18. A voltage doubler rectifier circuit connected between both ends of a secondary winding of the transformer, wherein the capacitor of the voltage doubler rectifier circuit also functions as the resonance capacitor. 3. The DC-D according to claim 2, wherein
C converter. 19. The DC-DC converter according to claim 18, wherein diodes are connected in anti-parallel between both ends of each capacitor of the voltage doubler rectifier circuit. 20. A full-wave rectifier circuit comprising a diode bridge connected between both ends of a secondary winding of the transformer, wherein the rectifier circuit includes a capacitor input connected between output terminals of the full-wave rectifier circuit. 3. A DC according to claim 2, further comprising a type smoothing circuit, wherein the capacitor of the capacitor input type smoothing circuit also serves as the resonance capacitor.
-DC converter. 21. A full-wave rectifier circuit comprising a diode bridge connected between both ends of a secondary winding of the transformer, wherein the choke coil is connected between output terminals of the full-wave rectifier circuit. 3. A series circuit comprising a capacitor for smoothing and a capacitor for smoothing, wherein the capacitor for resonance is connected between both ends of the secondary winding on the input side of the full-wave rectifier circuit. DC-DC converter. 22. The DC-DC converter according to claim 1, wherein the transformer has a plurality of secondary windings. 23. The method according to claim 1, wherein the transformer has a plurality of secondary windings, and the resonance capacitor is provided for each of the secondary windings. 3. The DC-DC converter according to 1. 24. The transformer has two secondary windings, a load is inserted between both ends of the secondary winding via a rectifying diode, and the resonance is provided between both ends of each secondary winding. The DC-DC converter according to any one of claims 1 to 15, wherein a capacitor for use in the DC-DC converter is inserted. 25. A configuration in which the resonance capacitor is connected between both ends of a secondary winding of the transformer, and a load is connected between both ends of the resonance capacitor via a DC cut capacitor. 2. The DC according to claim 1, wherein:
-DC converter. 26. A secondary winding of a transformer, comprising: a DC voltage source; and two switching elements each forming a closed loop together with the DC voltage source and an inductance element, converting an output voltage of the DC voltage source into an AC output. An inverter circuit for outputting to the transformer, the capacitor for resonance forming a resonance circuit with the transformer and the inductance element, and a rectifier circuit for converting an output voltage of the inverter circuit into a predetermined DC voltage and supplying the DC voltage to a load, In the inverter circuit, both switching elements are alternately turned on and off with a duty exceeding 50%, and energy is accumulated in the inductance element during a period in which both switching elements are overlapped and turned on, and one of the two switching elements is turned off. The stored energy of the inductance element is superimposed on the energy of the DC voltage source The first mode, which is then released to the primary winding of the transformer, constitutes a flyback converter with one switching element and the transformer, and forms a forward converter with the other switching element and the transformer. A second mode in which the switching element is turned on and off. 27. A direct current source, a capacitor connected in parallel with the direct current source, and a closed loop constituting together with the direct current source via a primary winding of a transformer.
An inverter circuit that includes two switching elements and converts an output current of the DC current source into an AC output and outputs the AC current to a secondary winding of a transformer; and an inductance element that forms a resonance circuit with the capacitor. A first period in which each switching element is alternately turned on and off with a duty of less than 50% and overlapped off.
And a second mode in which each switching element is alternately turned on and off at a frequency near the resonance frequency of the resonance circuit with a duty of 50%. 28. A direct current source, a capacitor connected in parallel to the direct current source, and a closed loop forming together with the direct current source via a primary winding of a transformer.
An inverter circuit that includes two switching elements and converts an output current of the DC current source into an AC output and outputs the AC current to a secondary winding of a transformer; and an inductance element that forms a resonance circuit with the capacitor. A first mode in which each switching element operates as a flyback converter together with a primary winding connected in series, and a second mode in which each switching element operates as a push-pull inverter in which each switching element is turned on and off at a duty of 50% DC characterized by having a mode
-DC converter.