JPH0919169A - Inverter device - Google Patents

Abstract

PURPOSE: To prevent the charging current to the smoothing capacitor of an inverter device and the resonance current of its inverter from canceling each other. CONSTITUTION: Switching elements Q1 , Q2 are connected in series with each other, and this series circuit is connected in parallel with a smoothing capacitor C0 . The one switching element Q1 is connected in series with an inductor L1 , and the output ends of a rectification circuit RE are connected by this series circuit. The energy stored in the inductor L1 when the switching element Q1 is in ON-state charges the smoothing capacitor C0 via a diode D8 when the switching element Q1 is in OFF-state. The switching elements Q1 , Q2 are turned on or off alternately to feed an AC power to a load with a discharge lamp DL. Further, a diode D9 is disposed in an inserting way between the switching elements Q1 , Q,2 m and thereby, the charging current to the smoothing capacitor C0 is prevented from being passed through the route including a diode D2 connected in parallel with the switching element Q2 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention rectifies an AC power source such as a commercial power source, charges a smoothing capacitor through a DC-DC converter, drives the inverter using the smoothing capacitor as a power source, and outputs from the inverter. The present invention relates to an inverter device that supplies AC power to a load circuit.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 10, an AC power source AC such as a commercial power source is full-wave rectified by a rectifier circuit RE composed of a diode bridge and then smoothed by a DC-DC converter composed of a step-up chopper circuit. Capacitor C ₀
There is provided an inverter device for charging the battery, driving the inverter using the smoothing capacitor C ₀ as a power source, and supplying the AC power output from the inverter to the load circuit.

In the DC-DC converter, a series circuit of an inductor L ₁ and a switch element Q ₁ is connected between the DC output terminals of a rectifying circuit RE, and a diode D ₅ connected in antiparallel to the switch element Q _2. It is configured by connecting a series circuit with the smoothing capacitor C ₀ in parallel with the switch element Q ₁ . Here, each switch element Q ₁ , Q ₂ has a MOSF
ET is used, and in FIG. 10, the switch element Q ₁ ,
The diodes D ₁ and D ₂ connected in antiparallel to Q ₂ are parasitic diodes. Further, between the inductor L ₁ and the switch element Q ₁ , there is such a polarity that a current flows through the inductor L ₁ when the switch element Q ₁ is turned on.
Diode D ₅ with cathode connected to switch element Q ₁
Is inserted.

[0004] switching element Q ₁ is turned on and off at a high frequency as will be described later, at the time of the on switch element Q _1, since a current flows from the rectifier circuit RE via an inductor L _1, the energy is stored in the inductor L ₁ ( 10). Further, when the switch element Q ₁ is off, the energy accumulated in the inductor L ₁ is released, and the charging current to the smoothing capacitor C ₀ flows through the diode D ₂ (path in FIG. 10). That is, when the switch elements Q ₁ and Q ₂ are turned on and off as shown in FIG.
The current I _D5 as shown in (b) flows through the diode D ₅ . When the smoothing capacitor C ₀ is charged, a voltage obtained by adding the voltage across the inductor L ₁ to the output voltage of the rectifier circuit RE is applied to the smoothing capacitor C _0. Therefore, the on / off ratio of the switch element Q ₁ should be adjusted. Thus, the voltage across the smoothing capacitor C ₀ can be made higher than the peak value of the output voltage of the rectifier circuit RE.

Further, when the switch element Q ₁ is on, a current flows from the rectifier circuit RE to the inductor L _0, and when the switch element Q ₁ is off, a charging current flows from the rectifier circuit RE and the inductor L ₁ to the smoothing capacitor C _0. , The rectifier circuit R regardless of the on / off state of the switch element Q _1.
The output current flows from E, and the input current from the AC power supply AC can continue to flow almost continuously. This shortens the quiescent period of the input current as compared to the case where only the smoothing capacitor is used, and consequently improves the input power factor.

On the other hand, the inverter includes a pair of switch elements Q ₁ and Q ₂ connected in series, and the switch element Q _{1 is connected} to D
It is also used as a C-DC converter. The series circuit of the switching elements Q ₁ and Q ₂ is connected across the smoothing capacitor C ₀ , and the current transformer CT is connected across the switching element Q _1.
, A primary winding, a ballast choke L ₂ as an inductance element, a DC cut capacitor C ₂ and a load circuit are connected in series. The load circuit includes a discharge lamp DL having a filament like a fluorescent lamp, and a preheating capacitor C ₄ connected to the non-power source side of the filament. The current transformer CT is provided with two secondary windings, one end of each secondary winding is connected to the gates of the switch elements Q ₁ and Q ₂ via resistors R ₁ and R ₂ , respectively, and the other end is a switch. Connected to the sources of elements Q ₁ and Q ₂ .

Now, if the switch element Q ₁ is on,
Using the capacitor C ₂ as a power source, the capacitor C ₂ −ballast choke L ₂ −primary winding of the current transformer CT −switch element Q
₁ -load circuit-current flows through the path of capacitor C ₂ (path of FIG. 10), and power is supplied to the load circuit from capacitor C ₂ . In addition, the induced voltage of one of the secondary windings connected to the switch element Q ₁ of the secondary windings of the current transformer CT has a polarity that controls the switch element Q ₁ to turn on, and the other secondary winding. The induced voltage on the line has a polarity that controls the switching element Q ₂ to be off. At this time, the DC-DC converter current flows from the rectifier circuit RE to the inductor L _1, the energy is accumulated in inductor L _1.

After that, when the current flowing in the primary winding of the current transformer CT becomes substantially constant, the induced voltage in the secondary winding decreases,
The switch element Q ₁ is controlled off. Switch element Q
_{When 1} is turned off, the energy stored in the ballast choke L ₂ and the current transformer CT is discharged as a regenerative current through the diode D ₂ . Further, since the polarity of the induced voltage in the secondary winding of the current transformer CT is reversed, the switch element Q ₁ is kept off and the switch element Q ₂ is controlled in the on direction.

If the regenerative current stops, the switching element Q ₂
Are controlled in the ON direction, so that the smoothing capacitor C ₀ or the rectifying circuit RE-the switch element Q ₂ -the primary winding of the current transformer CT-the ballast choke L ₂ -the capacitor C ₂ -the load circuit-the smoothing capacitor C _{0 to} rectifier circuit R
An electric current flows through the route E (route in FIG. 10). Here, the power source to the inverter is mainly the rectifier circuit RE in the peak portion period when the output voltage of the rectifier circuit RE is relatively high, and the main source of the smoothing capacitor C ₀ is the output voltage of the rectifier circuit RE. It is a relatively low valley period. Thus, the direction of the current flowing through the load circuit is opposite to that when the switch element Q ₁ is on. At this time, switch element Q
₁ is kept off and switch element Q ₂ is fully on. Further, in the DC-DC converter, the inductor L ₁
Energy is released from the rectifier circuit RE-inductor L
₁ -Diode D ₅ -Diode D ₂ -Smoothing capacitor C ₀ -Rectifier circuit RE A charging current flows to the smoothing capacitor C ₀ .

Even in this state, when the current flowing through the current transformer CT becomes substantially constant, the induced voltage in the secondary winding drops and the switch element Q ₂ is turned off. When the switching element Q ₂ is turned off, the primary winding of the current transformer CT and the ballast choke L ₂
The regenerative current flows through the diode D ₁ due to the release of the stored energy of Further, since the polarity of the induced voltage in the secondary winding of the current transformer CT is reversed, the switch element Q ₁ is controlled in the ON direction and the switch element Q ₂ is kept OFF. When the regenerative current is stopped, the switch element Q ₁ is completely turned on and the capacitor C ₂ is used as a power source. That is,
Currents I _Q1 and I _Q2 as shown in FIGS. 11C and 11D flow to the drains of the switch elements Q ₁ and Q ₂ .

As is clear from the above operation, the current transformer C
By the feedback of the current flowing through T, the switching elements Q ₁ , Q ₂
Are alternately turned on and off, and self-excited control is performed. Further, since the polarity of the voltage applied to the load circuit is inverted according to the ON / OFF of the switch elements Q ₁ and Q ₂ , it is possible to supply AC power to the load circuit.

[0012]

By the way, when the switching element Q ₁ is on, the current flowing through the switching element Q ₁ through the inductor L ₁ and the diode D ₅ in the DC-DC converter and the capacitor C ₂ in the inverter are supplied with power. The current flows in the same direction as the current flowing through the switch element Q ₁ so as to be supplied to the load circuit. However, when the switch element Q ₂ is on, DC-DC
Contrary to current flowing a charging current through the switching element Q ₂ toward the inductor L ₂ to the smoothing capacitor C ₀ in the converter, the switching element Q ₂ as supplied to the load circuit smoothing capacitor C ₀ as a power source in the inverter Turn to face. That is, the charging current from the inductor L ₂ to the smoothing capacitor C ₀ in the DC-DC converter flows simultaneously with the regenerative current passing through the diode D ₂ in the inverter, and the charging current to the smoothing capacitor C ₂ passing through the diode D ₂ is generated. Is stopped, discharge is started from the smoothing capacitor C ₂ . As a result, a quiescent period occurs in the current flowing through the inductor L ₁ while the smoothing capacitor C ₂ is discharging. The current to the load circuit flows through the switch element Q ₂ during this idle period.

It is assumed that the discharge lamp DL is restarted from a stable lighting state for some reason. At this time, the voltage across the smoothing capacitor C ₀ once drops to about the output voltage of the rectifier circuit RE, so the voltage obtained by adding the output voltage of the rectifier circuit RE and the voltage across the inductor L ₁ when the switch element Q ₁ is off. Then, the difference between the voltage across the smoothing capacitor C ₀ becomes large, and the period during which the current flows through the inductor L ₁ becomes longer than that during stable lighting of the discharge lamp DL. Further, since the discharge lamp DL is in a state of being easily lit at the time of restart and the resonance frequency of the resonance system including the load circuit is different from that at the time of starting, the current flowing in the primary winding of the current transformer CT is at the time of starting. Will be smaller than.

Therefore, if restarting from a stable lighting state, the charging current to the smoothing capacitor C ₀ flowing from the inductor L ₁ through the diode D ₂ cancels the discharging current of the smoothing capacitor C ₀ . As a result, the above-described pause period does not occur in the charging current to the smoothing capacitor C ₀ , and as shown in FIGS. 12B and 12C, the drains of the switch elements Q ₁ and Q ₂ mainly charge the smoothing capacitor C ₀ . The electric current comes to flow. In addition, a DC current flows through the load circuit and the switch elements Q ₁ , Q ₂
The potential at the connection point of does not fall to the negative potential of the rectifier circuit RE, and a sufficiently large induced voltage does not occur in the secondary winding of the current transformer CT, so that the oscillation operation of the inverter immediately stops after restarting. It will be. Since the inverter restarts when the oscillating operation is stopped, the discharge lamp DL is eventually restarted and turned off.
The light output of fluctuates and a phenomenon similar to flicker occurs.

The present invention has been made in view of the above reasons, and an object thereof is to prevent the charging current to the smoothing capacitor and the resonance current of the inverter from flowing in the same path in opposite directions at the same time. An object of the present invention is to provide an inverter device capable of stably operating the inverter by preventing it.

[0016]

According to a first aspect of the present invention, a rectifier circuit for rectifying an AC power source and a switch element that is turned on / off at a high frequency are provided, and an inductor is formed by a current passing through the rectifier circuit when the switch element is on. A DC-DC converter that discharges stored energy when the switch element is off to charge a smoothing capacitor, and a smoothing capacitor having at least one switch element including a switch element shared with the switch element of the DC-DC converter. In an inverter device including an inverter that converts a DC voltage at both ends into AC power using a resonance element including an inductance element and supplies the AC power to a load circuit, a current loop for flowing a charging current from an inductor to a smoothing capacitor, and the charging current And the current loop that flows the resonant current of the inverter flowing at the same time Characterized by comprising providing a current loop isolation means that.

According to a second aspect of the invention, the DC-DC converter includes a series circuit of a first switch element and an inductor connected between the DC output terminals of the rectifier circuit, and
The inverter includes a first diode inserted in a current loop that passes through the rectifier circuit, the inductor, and the smoothing capacitor so that a charging current from the inductor to the smoothing capacitor flows when the first switch element is turned off. A second switch element that is connected in series to the switch element via a second diode and that is alternately turned on / off with the first switch element is provided, and the first switch element, the second switch element, and the second switch element are provided. A series circuit with a diode is connected between both ends of the smoothing capacitor, and forms a current loop in the second switch element, in which a regenerative current generated by the inductance element flows in the opposite direction when the second switch element is off and when it is on. A third diode is connected in parallel and a second diode is connected to the third diode when the first switching element is off. Inductor and second polar to prevent
It is characterized in that the current loop separating means is configured with the first diode by being inserted between the switch element and the switch element.

In the invention of claim 3, the inverter is a DC
A second switch element that is connected in series with the first switch element that is shared with the DC converter and that is alternately turned on and off with the first switch element, the first switch element and the second switch A series circuit including an element is connected between both ends of the smoothing capacitor, and a series circuit including an inductance element, a DC cut capacitor, and a load circuit is provided in either one of the first switch element and the second switch element. The first switch element and the second switch element are connected in parallel, and a diode for flowing a regenerative current of the inductance element is connected in parallel to each of the first switch element and the second switch element.

In the invention of claim 4, the inverter is a DC
A switch element shared with the DC converter, a resonance inductor connected in series to the switch element, and a resonance capacitor forming a resonance circuit together with the resonance inductor, and including the switch element and the resonance inductor. The series circuit is connected between both ends of the smoothing capacitor, the switch element is connected in parallel with the series circuit of the inductance element, the DC cut capacitor, and the load circuit, and the switch element is connected in parallel with the diode for flowing the regenerative current of the inductance element. It is characterized by being connected physically.

According to a fifth aspect of the invention, the rectifier circuit is composed of a diode bridge, and the DC-DC converter includes an inductor inserted between an AC power source and an AC input end of the rectifier circuit and a DC output end of the rectifier circuit. Each of the diodes connected to both ends of the diode from the inductor when the first switch element is off, the smoothing capacitor connected to the first switch element and the first switch element connected in parallel to one of the diodes of the rectifier circuit. Form a current loop through which the charging current to the smoothing capacitor flows, and the inverter
Second switch element connected in series via a second diode and turned on / off alternately with the first switch element
And a series circuit of the first switch element, the second switch element, and the second diode is connected across the smoothing capacitor, and the second switch element receives the regenerative current generated by the inductance element. A third diode that forms a current loop that flows in a direction opposite to that when the second switch element is turned off is connected in parallel, and the second diode is switched from the inductor to the third diode when the first switch element is turned off. It is characterized in that the current loop separating means is configured together with the rectifying circuit by being inserted between the inductor and the second switch element with a polarity that blocks the flowing current.

According to a sixth aspect of the invention, the inverter includes a current transformer in which a primary winding is inserted in a series circuit including an inductance element, a DC cut capacitor, and a load circuit, and the secondary output of the current transformer is provided. It is characterized in that the switch element is turned on and off in a self-exciting manner. According to a seventh aspect of the invention, the inverter includes a control circuit that limits the ON period of the switch element.

The invention of claim 8 is characterized in that an inductance element for noise prevention is connected in series in such a manner that it is directly connected to a switch element shared by the DC-DC converter and the inverter. According to a ninth aspect of the invention, the load circuit includes a discharge lamp. According to the invention of claim 10, the DC-DC converter and the inverter are arranged close to the load circuit, the rectifying circuit and the smoothing capacitor are arranged on the side of the AC power supply, and the other circuit is arranged in the DC-DC.
It is characterized in that it is arranged between a converter and an inverter and a rectifying circuit and a smoothing capacitor.

[0023]

According to the structure of the present invention, the current loop separating means for independently providing the current loop for flowing the charging current from the inductor to the smoothing capacitor and the current loop for flowing the resonance current of the inverter flowing at the same time as the charging current are provided. Since it is provided, the charging current to the smoothing capacitor and the resonant current of the inverter do not cancel each other out when they try to flow in the same route in the opposite directions at the same time, so that the smoothing capacitor can be charged quickly and the inverter The reduction of the resonance current is prevented, and as a result, the inverter can be stably operated. Therefore, even when the discharge lamp is used in the load circuit as in the invention of claim 9, it is possible to prevent the occurrence of flicker by repeating light-out and restart without causing inconvenience such as instantaneous restart. it can.

[0024]

【Example】

(Embodiment 1) As shown in FIG. 1, the construction of this embodiment is basically the same as that of the conventional example shown in FIG.
In adding three diodes D ₈ to D ₁₀ to the circuit configuration of different. Therefore, the description of the components denoted by the same reference numerals as in FIG. 10 is omitted. The diode D ₈ has its anode connected to a connection point between the inductor L ₁ and the anode of the diode D ₅ , and its cathode connected to the positive electrode of the smoothing capacitor C ₀ . Further, the diode D ₉ is inserted between the pair of switch elements Q ₁ and Q ₂ in such a manner that the anode is connected to the switch element Q ₂ and the cathode is connected to the switch element Q ₁ . The diode D ₁₀ has a structure in which the cathode is connected to the anode of the diode D _9.
It is connected in parallel to the series circuit of ₉ and the switch element Q ₁ .

[0025] Thus, the diode D ₈ is inserted in a path to flow a charging current from the inductor L ₁ to the smoothing capacitor C _0, the diode D ₉ smoothing capacitor C ₀ current flows through the diode D ₂ by the release energy of the inductor L ₁ It has a function to prevent it from flowing into. Further, the diode D ₁₀ forms a current loop of the resonance current in place of the diode D ₁ when the switch element Q ₁ functions as a constituent element of the inverter.

The operation of this embodiment will be described in more detail. Switching element Q similar to the conventional configuration shown in FIG.
_{Since 1} and Q ₂ are turned on and off alternately at high frequency, DC
In -DC converter, passing a current through the inductor L ₁ and the diode D ₅ from the rectifier circuit RE during on of the switch element Q _1, stores energy in the inductor L ₁ (path of the FIG. 1). When the switch element Q ₁ is turned off, the energy stored in the inductor L ₁ is released, and the charging current to the smoothing capacitor C ₀ flows through the diode D ₈ (path in FIG. 1). Since the diode D ₉ is provided here, the inductor L
The charging current from ₁ to the smoothing capacitor C ₀ is diode D
Blocked from passing through ₂ . Thus, DC-D
When viewed from the AC power supply AC, the C converter operates in the same manner as the conventional configuration, and thus has a high input power factor.

On the other hand, the inverter uses the capacitor C ₂ as a power source and the capacitor C ₂ while the switch element Q ₁ is on.
₂ - primary winding of the ballast choke L ₂ over current transformer CT - diode D ₉ - switching element Q ₁ - load circuit - a current flows in a path of the capacitor C _2, powered from the capacitor C ₂ to the load circuit (Fig. Route 1). When the switching element Q ₁ is turned off, the energy stored in the ballast choke L ₂ and the current transformer CT is discharged as a regenerative current through the diode D ₂ .

If the regenerative current stops, the switching element Q ₂
Are controlled in the ON direction, so that the smoothing capacitor C ₀ or the rectifying circuit RE-the switch element Q ₂ -the primary winding of the current transformer CT-the ballast choke L ₂ -the capacitor C ₂ -the load circuit-the smoothing capacitor C _{0 to} rectifier circuit R
An electric current flows through the route E (route in FIG. 1). That is, the direction of the current flowing through the load circuit is opposite to that when the switch element Q ₁ is on. After that, when the switch element Q ₂ is turned off, the regenerative current flows through the diode D ₁₀ due to the discharge of the energy stored in the primary winding of the current transformer CT and the ballast choke L ₂ .

As is apparent from the above operation, according to the configuration of this embodiment, there is no current that tries to flow in the same route in the opposite direction at the same time, and the currents do not cancel each other. As a result, the resonance current of the inverter is not disturbed by the current flowing as the charging current to the capacitor C ₀ in the DC-DC converter, and the oscillation operation of the inverter is prevented from being stopped. That is, the fluctuation of the light output due to the restarting and extinguishing of the discharge lamp DL is prevented.

Furthermore, in the conventional configuration shown in FIG. 10, as shown in FIG. 2 (b), a diode D _5, the period and the inductor L ₁ for storing energy in the inductor L ₁ and the period of emitting energy Since the current was flowing in both of the above, the amount of heat generated by the diode D ₅ was large. On the other hand, in the configuration of the present embodiment, the current flows through the diode D ₅ only during the period when energy is stored in the inductor L ₁ as shown in FIG. 2C, and during the period when the energy of the inductor L ₁ is released. 2D, a current flows through the diode D ₈ as shown in FIG. 2D, so that the temperature rise of each of the diodes D ₅ and D ₈ is reduced as compared with the temperature rise of the diode D ₅ having the conventional configuration. Here, FIG. 2 (a) the drain of the switching element Q ₁ - shows the source voltage, the switch element Q ₁ at 0V is turned on, the switch element Q ₂ is turned off.

(Embodiment 2) In this embodiment, as shown in FIG. 3, bipolar transistors are used as the switching elements Q ₁ and Q ₂ . Therefore, the switching element Q
_The diode D ₂ is connected in antiparallel between the collector and the emitter of _2.
Is connected. Further, since the regenerative current by the current transformer CT and the ballast choke L ₂ passes through the diode D ₁₀ ,
The diode D ₁ is not connected to the switch element Q ₁ . The configuration of the present embodiment is different only in that the MOSFET of the first embodiment is replaced with a bipolar transistor and a diode D ₂ as the switch elements Q ₁ and Q ₂ , and other configurations and operations are the same.

(Embodiment 3) In this embodiment, as shown in FIG. 4, a switching element Q ₂ and a diode D ₂ in the configuration of Embodiment 1 shown in FIG. 1 are connected in parallel with an inductor L ₃ and a capacitor C _3. It is replaced with a resonance circuit. In this configuration, when the switch element Q ₁ is turned on, the capacitor C ₂ −ballast choke L ₂ −primary winding of the current transformer CT−
Diode D ₉ −Switching element Q ₁ −Load circuit −In addition to the path of capacitor C ₂ , smoothing capacitor C ₀ −Resonant circuit including inductor L ₃ and capacitor C ₃ −
Diode D ₉ -Switch element Q ₁ -Smoothing capacitor C
_The current flows through the path of ₀ . Next, switch element Q
_{When 1} is turned off, the resonance circuit oscillates freely, and after the regenerative current by the ballast choke L ₂ and the current transformer CT flows through the resonance circuit and the smoothing capacitor C ₀ , the capacitor C ₀ or the rectifying circuit RE-inductor L. _A current flows through a path of a resonance circuit composed of ₃ and a capacitor C ₃ , a primary winding of the current transformer CT, a ballast choke L _{2, a} capacitor C _{2, a} load circuit, and a smoothing capacitor C ₀ . When the current flowing through the primary winding of the current transformer CT starts to decrease due to the resonance current flowing through the resonance circuit, the switch element Q ₁ is controlled in the ON direction, and the regenerative current of the current transformer CT and the inductor L ₂ is changed to the diode D. Flowing through ₁₀ . When this regenerative current is stopped, a current flows again through the switch element Q ₁ , and as a result, the same operation as when the _two switch elements Q ₁ and Q ₂ are provided is performed.

Other configurations and operations are similar to those of the first embodiment, and the MOSF shown as the switch element Q ₁ is shown.
It goes without saying that a bipolar transistor may be used instead of ET to operate similarly. (Embodiment 4) In this embodiment, as shown in FIG.
The switching elements Q ₁ and Q _{2 in the above} are replaced with MOSFETs from bipolar transistors, and an inductor L ₁ is inserted between the AC power supply AC and the rectifier circuit RE. Further, the diode D _{5 serving as} a current path for storing energy in the inductor L ₁ is inserted between the switch element Q ₁ and the negative electrode of the rectifier circuit RE, and the load circuit is on the low side (negative electrode side of the smoothing capacitor C ₀ ). Are connected in series to the switch element Q ₂ (in the above embodiment, in parallel). The rectifier circuit RE is a diode D
A series circuit of ₈₁ and D _{82 and} a series circuit of diodes D ₁₁ and D ₁₂ are connected in parallel to each other to form a diode bridge. The connection point of the diodes D ₈₁ and D ₈₂ and the diode D
The connection point of ₁₁ and D ₁₂ becomes the AC input terminal. Further, in the circuit configuration of the present embodiment, not only the switch element Q ₁ but also the switch element Q ₂ is used for boosting in the DC-DC converter, and the switch element Q ₁ and the switch element Q are used.
A diode D _91, which is inserted in a manner of connecting the anode to the switching element Q ₂ between the _2, switching element Q ₁
Between switching element Q ₁ and the anode of diode D ₈₂
And a diode D ₉₂ inserted so that the anode is connected to.

Next, the operation of this embodiment will be described.
The DC-DC converter supplies a current through the inductor L ₁ -switch element Q ₁ -diode D ₉₂ -diode D ₁₂ when the switch element Q ₁ is on during the period in which the lower end side of the AC power supply AC shown in FIG. 5 becomes positive. When the switching element Q ₁ is off, the energy stored in the inductor L ₁ is discharged through the path of the diode D ₈₁ -smoothing capacitor C ₀ -diode D ₁₂ to charge the smoothing capacitor C ₀ . At this time, due to the presence of the diode D ₉₁ , no current flows from the inductor L ₁ to the smoothing capacitor C ₀ in the diode D ₂ .

Further, during the period in which the upper end side of the AC power source AC shown in FIG. 5 is positive, when the switch element Q ₂ is turned on,
Diode D ₁₁ -Switch element Q ₂ -Diode D _91-
A current flows through the path of the inductor L ₁ , and when the switch element Q ₂ is off, the energy accumulated in the inductor L ₁ is transferred to the diode D ₁₁ −smoothing capacitor C ₀ −diode D.
_The smoothing capacitor C ₀ is charged by discharging through the path ₈₂ . At this time, due to the presence of the diode D ₉₂ , no current flows from the inductor L ₁ to the smoothing capacitor C ₀ in the diode D ₁₀ .

The inverter operates almost in the same way as in the first embodiment. However, the smoothing capacitor C ₀ to the rectifier circuit RE when the on switch element Q ₁ and a power supply, that operates the capacitor C ₂ as a power source when the on switch element Q ₂ are different. That is, when the switching element Q ₁ is turned on, the smoothing capacitor C ₀ or the rectifying circuit RE-capacitor C ₂ -load circuit-ballast choke L _2- primary winding of the current transformer CT-diode D ₉₁ -switch element Q ₁
-A current flows through the path of the smoothing capacitor C ₀ or the rectifier circuit RE, and the current flows from the top to the bottom of FIG. 5 with respect to the load circuit. The switch when the element Q ₁ is turned off, the ballast choke L ₂ and current transformer CT regenerative current by the switching element Q ₂ in parallel diode D ₂
Will flow through. Further, since the switch element Q ₂ is controlled in the ON direction at the time when the regenerative current flows, the capacitor C ₂ −switch element Q ₂ −primary winding of the current transformer CT−ballast choke along with the stop of the regenerative current. L
₂ -Load circuit-Current flows through the route of capacitor C ₂ .

As described above, since the switching elements Q ₁ and Q ₂ are shared by both the DC-DC converter and the inverter, current does not flow in the opposite direction at the same time in the same route. Similarly, the inverter continues stable operation. In addition, the positive half cycle of the AC power supply AC (see FIG.
Switch element Q ₂ is DC-DC
Used in the converter, the switch element Q ₁ is used in the DC-DC converter in the negative half cycle of the AC power supply AC.

Other configurations and operations are the same as those of the first embodiment, and it goes without saying that the same operation is performed even if a MOSFET is used as the switch element Q ₁ instead of the bipolar transistor shown in the figure. In that case,
Since the diode D ₂ is realized by a parasitic diode of MOSFET, the diode D ₂ becomes unnecessary. (Embodiment 5) As shown in FIG. 6, this embodiment has a structure in which a control circuit CN for controlling the switch element Q ₁ is added to the structure of the embodiment 1 shown in FIG. Control circuit CN
Is fed by the smoothing capacitor C ₀ or the rectifying circuit RE, and limits the ON period of the switch element Q ₁ according to the voltage across the smoothing capacitor C ₀ . That is, DC-DC
In order to stabilize the voltage across the smoothing capacitor C _{0 in} the converter, the switching element Q is controlled by the control circuit CN.
The on-duty of ₁ is controlled. Other configurations and operations are the same as those of the first embodiment. By the way, in this embodiment,
Components are mounted on a circuit board PB made of a printed wiring board in a form as shown in FIG. That is, the terminal portion T ₁ connected to the AC power supply AC is provided at one end portion in the longitudinal direction of the rectangular circuit board PB, and the terminal portion T ₂ connected to the load circuit is provided at the other end portion, and the terminal portion T _{From 2} to the terminal portion T ₁ , main parts of the DC-DC converter and the inverter surrounded by the broken line in FIG. 6, the control circuit CN, FIG.
A rectifier circuit RE, an inductor L ₁ and a diode D ₈ surrounded by a solid line are sequentially arranged. That is, the components forming the main parts of the DC-DC converter and the inverter, which often perform switching operations, are mounted in a portion close to the load circuit. If such an arrangement is adopted, as shown in FIG. 7B, an inverter, a control circuit CN, a DC-DC converter, a rectifier circuit RE, and an inductor L _{1 are} called from the terminal portion T ₂ toward the terminal portion T _1. The distance between the circuit portion that performs the switching operation and the load circuit becomes smaller than that in the case of the arrangement. As a result, the load circuit and DC-DC
The area of the current loop formed by the converter and the inverter can be reduced, and the radiation noise can be reduced.

(Embodiment 6) In this embodiment, as shown in FIG. 8, with respect to the structure of Embodiment 1 shown in FIG. 1, a diode D ₅ and a diode D ₉ are connected from the drain of the switch element Q _1.
Ferrite beads FB are mounted as an inductance element for noise prevention in the electric path leading to the connection point between the cathodes of and. This is, the switch element Q ₁ DC-
Since currents of both the DC converter and the inverter flow simultaneously and noise is likely to occur, selecting the drain of the switch element Q ₁ as the place where the ferrite bead FB is mounted increases the noise reduction effect. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 7) In this embodiment, as shown in FIG. 9, the discharge lamp DL is mounted in the sockets SK ₁ and SK _2, and the construction of the embodiment 1 shown in FIG. With respect to the above, a protection means for preventing circuit breakage due to a minute contact failure between the discharge lamp DL and the sockets SK ₁ and SK ₂ is provided. That is, the discharge lamp DL and the socket SK
_1, the SK ₂ and the minute contact failure between the results, a high voltage is generated at both sockets SK _1, a high impedance will both socket SK ₁ between SK _2, SK _2. If such a high voltage occurs, it will lead to the destruction of the switch elements Q ₁ , Q _2, etc.

Therefore, in this embodiment, the switch element Q ₁
Between the gate and the source of the transistor S ₁
Insert a parallel circuit of the emitter and the phototransistor S ₂ which is the light receiving element of the photocoupler PC, and insert the socket SK
_The voltage applied to ₁ and SK ₂ is monitored, and sockets SK ₁ and S
When the product of the voltage applied to K ₂ and its duration exceeds a predetermined value, the transistor S ₁ or the phototransistor S ₂ is turned on and the switch element Q ₁ is turned off to stop the operation of the DC-DC converter and the inverter. Is done.

As a circuit for detecting the voltage applied to the sockets SK ₁ and SK ₂ , a diode D ₁₅ and a resistor R ₁₅ are provided between the power source side and the non-power source side of the socket SK ₂ provided on the high voltage side of the discharge lamp DL. , Insert a series circuit of capacitor C ₁₅ ,
A series circuit of a light emitting diode E which is a light emitting element of the photocoupler PC and a resistor R ₁₄ is connected to the capacitor C ₁₅ . Further, the socket S provided on the low pressure side of the discharge lamp DL
A series circuit of a diode D ₁₆ , a resistor R ₁₆ and a capacitor C ₁₆ is inserted between the non-power source side and the power source side of K ₁ , and the base of the transistor S ₁ is connected to the capacitor C ₁₆ via the resistor R _13. To be done.

According to the above construction, both sockets SK ₁ , S
When there is a light or no load between K ₂ , socket SK
₁ , the voltage applied to SK ₂ increases, and
₁₅ or the voltage across the capacitor C ₁₆ is the resistance R ₁₅ , R ₁₆
Increases with a predetermined time constant determined by the transistors S ₁
Alternatively, the phototransistor S ₂ is turned on. That is,
When the transistor S ₁ or the phototransistor S ₂ is turned on, the switch element Q ₁ is turned off and the DC-DC
The operation of the converter and the inverter is stopped. With this configuration, even if the discharge lamp DL is removed during operation, the DC-DC converter and the inverter are immediately stopped, and an electric shock due to a high voltage being applied to the sockets SK ₁ and SK ₂ is prevented. You can

Other configurations and operations are similar to those of the first embodiment.

[0045]

According to the structure of the present invention, the current loop separating means for independently providing the current loop for flowing the charging current from the inductor to the smoothing capacitor and the current loop for flowing the resonance current of the inverter flowing at the same time as the charging current are provided. Since it is provided, the charging current to the smoothing capacitor and the resonance current of the inverter do not cancel each other out when they try to flow in the opposite direction on the same path at the same time, so that the smoothing capacitor can be charged quickly and the inverter There is an advantage that the reduction of the resonance current is prevented and, as a result, the inverter can be stably operated.

In particular, when a discharge lamp is used in the load circuit as in the invention of claim 9, flicker is prevented by repeating light-off and restart without causing inconvenience such as instantaneous restart. There is an advantage that can be done.

[Brief description of the drawings]

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

FIG. 2 is an operation explanatory diagram of the first embodiment.

FIG. 3 is a circuit diagram showing a second embodiment.

FIG. 4 is a circuit diagram showing a third embodiment.

FIG. 5 is a circuit diagram showing a fourth embodiment.

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

FIG. 7A is a diagram showing a mounting form on a circuit board according to a fifth embodiment, and FIG. 7B is a diagram showing a mounting form on a conventional circuit board.

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

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

FIG. 10 is a circuit diagram showing a conventional example.

FIG. 11 is an operation explanatory diagram of a conventional example.

FIG. 12 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

AC AC power supply C ₀ Smoothing capacitor C ₂ capacitor C ₃ capacitor CN Control circuit CT Current transformer D ₁ diode D ₂ diode D ₅ diode D ₈ diode D ₉ diode D ₁₀ diode DL discharge lamp L ₁ inductor L ₂ ballast choke Q ₁ Switch element Q ₂ Switch element RE Rectifier circuit

Claims (10)

[Claims] 1. A rectifier circuit for rectifying an AC power supply, and a switch element that is turned on and off at a high frequency, and releases energy accumulated in an inductor by a current passing through the rectifier circuit when the switch element is on, when the switch element is off. DC-DC converter that charges the smoothing capacitor by
The DC voltage across the smoothing capacitor having at least one switch element including a switch element shared with the switch element of the DC converter is converted into AC power using a resonance element including an inductance element and supplied to a load circuit. In an inverter device provided with an inverter, a current loop separating means is provided for making a current loop for flowing a charging current from an inductor to a smoothing capacitor and a current loop for flowing a resonance current of an inverter flowing at the same time as this charging current independent from each other. An inverter device characterized by being formed. 2. The DC-DC converter includes a series circuit of a first switch element connected between DC output terminals of a rectifying circuit and an inductor, and when the first switch element is off, the inductor changes from a smoothing capacitor to a smoothing capacitor. Comprising a first diode inserted in the current loop through the rectifier circuit, the inductor and the smoothing capacitor to carry the charging current of the inverter, the inverter being connected in series with the first switch element via the second diode. A second switch element that is turned on and off alternately with the first switch element is provided, and a series circuit of the first switch element, the second switch element, and the second diode is connected across the smoothing capacitor. In the second switch element, a regenerative current generated by the inductance element is caused to flow in the opposite direction when the second switch element is off and when it is on. A third diode forming a loop is connected in parallel, and the second diode is connected between the inductor and the second switch element with a polarity that blocks a current flowing from the inductor to the third diode when the first switch element is off. 5. The current loop separating means is configured with the first diode by being inserted into the first diode.
The inverter device as described. 3. The inverter is connected in series with a first switch element that is shared with a DC-DC converter.
A second switch element that is turned on and off alternately with the switch element, and a series circuit including the first switch element and the second switch element is connected across the smoothing capacitor, A series circuit including an inductance element, a DC cut capacitor, and a load circuit is connected in parallel to either one of the element and the second switch element, and
2. The inverter device according to claim 1, wherein the switch element and the second switch element are each connected in parallel with a diode for flowing a regenerative current of an inductance element. 4. The inverter includes a switch element shared with the DC-DC converter, a resonance inductor connected in series with the switch element, and a resonance capacitor forming a resonance circuit together with the resonance inductor. A series circuit including a switch element and a resonance inductor is connected across the smoothing capacitor, a series circuit including an inductance element, a DC cut capacitor, and a load circuit is connected in parallel to the switch element, and the switch element has an inductance. 2. The inverter device according to claim 1, wherein diodes for flowing a regenerative current of the elements are connected in parallel. 5. The rectifier circuit comprises a diode bridge, and the DC-DC converter has a smoothing element connected between an AC power source and an AC input terminal of the rectifier circuit, and a DC output terminal of the rectifier circuit. A capacitor and a first switch element connected in parallel with one of the diodes of the rectifier circuit are provided, and when the first switch element is off, the inductor is connected to the smoothing capacitor through each diode connected across the diode. The inverter includes a second switch element that forms a current loop that flows a charging current, and the inverter is connected in series to the first switch element via a second diode and is turned on / off alternately with the first switch element. , A first switch element and a second switch element and a second
The series circuit with the diode is connected between both ends of the smoothing capacitor, and the second switch element forms a current loop in which the regenerative current generated by the inductance element flows in the opposite direction when the second switch element is off. A third diode connected in parallel, and the second diode is inserted between the inductor and the second switch element with a polarity that blocks a current flowing from the inductor to the third diode when the first switch element is off. The inverter device according to claim 1, wherein the current loop separating means is configured together with the rectifying circuit. 6. The inverter comprises a current transformer in which a primary winding is inserted in a series circuit of an inductance element, a DC cut capacitor and a load circuit, and a switching element is provided by a secondary output of the current transformer. The inverter device according to claim 3, wherein the inverter device is turned on / off by excitation. 7. The inverter comprises a control circuit for limiting an ON period of the switch element.
The inverter device as described. 8. The inverter according to claim 1, wherein an inductance element for noise prevention is connected in series so as to be directly connected to a switching element shared by the DC-DC converter and the inverter. apparatus. 9. The inverter device according to claim 1, wherein the load circuit includes a discharge lamp. 10. A DC-DC converter and an inverter are arranged in proximity to a load circuit, a rectifying circuit and a smoothing capacitor are arranged on the side of an AC power source, and another circuit is a DC circuit.
The inverter device according to claim 9, wherein the inverter device is arranged between the DC converter and the inverter and the rectifying circuit and the smoothing capacitor.