JPH0710180B2 - Inverter device - Google Patents

Description

The present invention relates to an inverter device for supplying power to a discharge lamp or the like.

[Conventional technology]

Conventional 1 transistor type inverter device, as shown in FIG. 5, intermittently switching elements Tr ₁ composed of transistors provided between the DC power source E and the load circuit LC ₁ by off to the load circuit LC ₁ It is designed to supply power to.

Further, the voltage of the DC power source E charges the capacitor C ₀ for smoothing the power source through the resistor R ₀ , and the capacitor for smoothing the power source is charged.
The control circuit power supply voltage V _C0 obtained at both ends of C ₀ is the control circuit CR ₁
Which causes the control circuit CR ₁ to supply an on / off control signal to the switching element Tr ₁ .

In such a one-stone type inverter device, when the switching operation of the switching element Tr ₁ is started, it operates as follows. When the DC power supply E is turned on, a current flows from the DC power supply E through the resistor R ₀ to the parallel circuit of the capacitor C ₀ and the Zener diode ZD ₀ , and the control circuit power supply voltage V _C0 is obtained. The control circuit power supply voltage V _C0 obtained across the capacitor C ₀ charges the capacitor C ₅ through the resistor R ₁₄ , and the voltage V _C5 across the capacitor C ₅ rises as shown in FIG. 6 (a). To do. When the voltage V _C5 across the capacitor C ₅ exceeds the threshold voltage V _T that is the turn-on voltage of the voltage response switch element SBS plus the base-emitter voltage V _BE of the transistor that is the switching element Tr ₁ , the voltage response switch element SBS Is turned on, and the electric charge of the capacitor C ₅ is discharged to the control pole (base) of the switching element Tr ₁ through the resistor R ₁₅ and the voltage response switching element SBS, and as a result, through the resistor R ₁₅ and the voltage response switching element SBS. The starting current I _SBS will flow to the control pole (base) of the switching Tr ₁ as shown in FIG. 6 (b). This starting current I _SBS will decrease as the voltage V _C5 across the capacitor C ₅ decreases.
The start-up current I _SBS shown in FIG. 6 (b) turns on the switching element Tr ₁ as shown in FIG. 6 (c) to start the switching operation.

Then, when the electric charge of the capacitor C ₅ is sufficiently discharged and the starting current I _SBS becomes smaller than the holding current I _H of the voltage response switch element SBS, the switching element Tr ₁ is turned off and the charging of the capacitor C ₅ is restarted.

After that, the above operation is repeated. As a result, the pulsed starting current I _SBS is repeatedly supplied to the control pole of the switching element Tr ₁ .

When the load current flows through the load circuit LC ₁ due to the supply of the starting current I _SBS to the switching element Tr _{1 described} above, the oscillation detection circuit DT ₂ detects this and turns on the transistor Tr ₇ . As a result, the charge of the capacitor C ₅ is forcibly released, the voltage V _C5 across the capacitor C ₅ does not reach the threshold voltage V _T , the voltage response switch element SBS maintains the cutoff state, and the switching element Tr ₁ Supply of start-up current I _SBS to is stopped. After the supply of the starting current I _SBS is stopped, the load circuit
Is supplied drive current from the secondary side of the current transformer CT ₁ in LC ₁ to a switching element Tr ₁ of the control electrode (base), the switching operation of the switching element Tr ₁ persists.

When the load LD is not connected and there is no load, the load circuit LC ₁
Since the load current does not flow to the
The supply of I _SBS will be repeated.

The on / off control signal for switching on / off of the switching element Tr ₁ is applied to the control pole (base) of the switching element Tr ₁ from the control circuit CR ₁ to which the control circuit power supply voltage V _C0 is supplied.

When the load circuit LC ₁ is intermittently supplied with DC power by the switching element Tr ₁ , the resonance circuit including the capacitor C ₂ and the oscillating transformer L ₃ causes a discharge lamp load.
An oscillating current will be supplied to the LD.

[Problems to be Solved by the Invention]

In the inverter device shown in FIG. 5, the starting current I _SBS
Is smaller than the holding current I _H of the voltage response switching element SBS, the starting current I _SBS is cut off by using the fact that the voltage response switching element SBS cuts off. Holding current I _H is several hundred μA
If for extremely small, the starting current I _SBS holding current I flowing to discharge the capacitor C ₅ to the voltage responsive switch element SBS
_In order to turn off the voltage response switch element SBS by making it smaller than _H, it is necessary to increase the resistance value of the resistor R ₁₄ and decrease the resistance value of the resistor R ₁₅ .

However, when the resistance values of the resistors R ₁₄ and R ₁₅ are set in this way, an unnecessarily large starting current I _SBS flows when the voltage response switch element SBS is turned on, and the switching element Tr ₁ and the voltage response switch element SBS are May be destroyed.

On the other hand, since the holding current I _{H of} the voltage response switch element SBS is small as described above, it takes time to turn off. That is, the ON time of the voltage response switch element SBS is likely to be long, and the starting current I _SBS is continuously supplied to the switching element Tr ₁ for a longer time than necessary. If the long-time start-up current I _SBS is continuously supplied in this manner, abnormal oscillation may occur between the capacitor C ₂ and the oscillation transformer L ₃ when there is no load, or overcurrent may flow into the switching element Tr ₁ and damage it. .

For such a problem, in FIG. 5, if the resistance value of the resistor R ₁₅ is made small and the discharge of the capacitor C ₅ is made fast, it is possible to shorten the time for supplying the starting current I _SBS .
As described above, since a larger starting current I _SBS flows than necessary, there is a limit to shortening the time for supplying the starting current I _SBS .

The fifth diagram of an inverter device, Yes and circuit configuration using the voltage responsive switch element SBS, since it is integrated integral with the voltage response switching elements other parts of SBS is difficult, the control circuit CR ₁ In the case where the start-up circuit section is formed as a dedicated integrated circuit, the voltage response switch element SBS has to be externally attached, which causes a problem of high cost and large size.

It is considered that the above problems are due to the use of the timer circuit including the voltage response switch element SBS in order to periodically generate the starting current. Therefore, it is expected that the above problems will be solved if the circuit configuration can be used without using the voltage response switch element SBS to periodically generate the starting current.

An object of the present invention is to provide an inverter device that can be started up without using a non-linear voltage response switch element, and can be achieved at a small size and at low cost.

[Means for Solving the Problems]

The inverter device of the present invention, which includes a switching element and is connected to a DC power source to generate a high frequency output voltage, is configured as follows. That is, a series circuit of a first resistor and a first capacitor that form a control circuit power supply is connected to both ends of a DC power supply, and a series circuit of a second resistor and a first switch is connected to both ends of the first capacitor. In addition, the series circuit of the second capacitor and the second switch is connected via the control pole of the switching element. Further, the discharge element for discharging the electric charge of the second capacitor is connected in parallel with the second capacitor. When the voltage of the first capacitor exceeds the upper set value, the first and second switches are turned on, and when the voltage of the first capacitor falls below the lower set value, the first and second switches are turned off. A switch control circuit for setting the state is provided.

[Action]

According to the configuration of the present invention, the switch control circuit detects the voltage of the first capacitor, turns on the first and second switches when the voltage exceeds the upper set value, and lowers the lower set value. Then, the first and second switches are turned off.

When the first and second switches are off, the first capacitor is charged through the first resistor and the voltage of the first capacitor rises.

When the voltage of the first capacitor exceeds the upper set value, the first and second switches are turned on and the first switch
The starting current is supplied to the control pole of the switching element from the second capacitor through the parallel circuit of the second capacitor and the discharging element and the second switch. At the same time, the first
Capacitor is discharged, and the voltage of the first capacitor drops.

After that, when the voltage of the first capacitor drops to a predetermined value, the starting current no longer flows in the control pole of the switching element, the switching element is cut off, and the control pole of the switching element is further controlled by the voltage across the second capacitor. Is applied with a reverse bias voltage, followed by discharge of the first and second capacitors.

After that, when the voltage of the first capacitor drops and falls below the lower set value, the first and second switches are turned off, the initial state is restored, and the above operation is repeated. The pulsed starting current is repeatedly supplied.

〔Example〕

A first embodiment of the present invention will be described with reference to FIGS. The inverter device, as shown in FIG. 1, which intermittently powered by turning on and off the switching elements Tr ₁ composed of transistors provided between the DC power source E and the load circuit LC ₁ to the load circuit LC ₁ In the above, the circuit configuration is characterized by supplying a starting current to the control pole (base) of the switching element Tr ₁ . That is, in this inverter device, the DC power source E is connected in series with the first resistor R ₀ and the first capacitor C ₀ for smoothing the power source.
C ₀ and the second resistor R ₁ and a first series circuit of a switch S ₁ is connected in parallel, a first resistor R ₀ and the first connection point between the capacitor C ₀ and the switching elements Tr ₁ control electrode (Base) with resistor R ₂ , second capacitor C ₁ and second switch S
Connect a series circuit of ₂ and connect the discharge element R ₃ consisting of a resistor to the second
Connected in parallel with the capacitor C _1, the control circuit power supply voltage V _C0 appearing across the first capacitor C ₀ is the first and second switches S _1, S ₂ on state when it exceeds the upper set value At the same time, a switch control circuit CR ₂ is provided which turns off the first and second switches S ₁ and S ₂ when the control circuit power supply voltage V _C0 across the first capacitor C ₀ falls below the lower set value. ing.

ST is a start / stop circuit that detects that a load current has flowed in the load circuit LC ₁ and holds the first and second switches S ₁ and S ₂ in an off state, and has priority over the switch control circuit CR ₂ . C
R ₁ is a control circuit that operates when a control circuit power supply voltage V _C0 is applied and that gives an on / off control signal to the switching element Tr ₁ as in the conventional example.

In the circuit shown in FIG. 1, the discharge element R ₃ is a resistor
It may be connected in parallel with the series circuit of R ₂ and the second capacitor C ₁ . As the discharging element R _3, as well as use of discrete components, it is also possible to use the internal impedance of the capacitor C _1.

Next, the operation of this inverter device will be described. The first capacitor C ₀ is charged from the DC power supply E through the first resistor R ₀ , and the control circuit power supply voltage V _C0 is obtained across the first capacitor C ₀ .

Then, the switch control circuit CR ₂ detects the control circuit power supply voltage V _C0 , and when the control circuit power supply voltage V _C0 exceeds the upper set value V _L1 (see FIG. 2), the first and second switches
Turn on S ₁ and S ₂ . On the other hand, when the control circuit power supply voltage V _{C0 at} the connection point between the first R ₀ and the first capacitor C ₀ falls below the lower set value V _L2 (see FIG. 2), the first and second switches S ₁ and S ₂ are turned off.

The first capacitor C ₀ is charged when the first and second switches S ₁ and S ₂ are off.

When the first and second switches S ₁ and S ₂ are turned on,
Through the control circuit power supply voltage V _C0 across the first capacitor C ₀ , the parallel circuit of the resistor R ₂ , the capacitor C ₁ and the discharge element R ₃ and the second switch S ₂ through the switching element Tr ₁
Starting current I _S1 flows through the control pole (base) of. At the same time, the charge of the first capacitor C ₀ is changed to the first switch.
When it is discharged through S ₁ and the second resistor R ₁ and the control circuit power supply voltage V _C0 drops to a predetermined value, the starting current I _S1 disappears and the switching element Tr ₁ shuts off, after which the second capacitor C ₁ A reverse bias voltage will be applied to the control pole of the switching element Tr ₁ .

After that, when the first and second switches S ₁ and S ₂ are turned off, the charging of the first capacitor C ₀ is started and the above operation is repeated.

The operation of the circuit shown in FIG. 1 will now be described in detail with reference to FIGS. 2 (a) to 2 (e). In FIG. 2, (a) shows a change in the control circuit power supply voltage V _C0 ,
(B) shows a change in voltage V _C1 , (c) shows a change in starting current I _S1 , (d) shows an on / off state of switching element Tr ₁ , and (e) shows first and second switches. S ₁ , S ₂
Shows the on / off state of.

Before time t ₀ , the first and second switches S ₁ , S
₂ is in the off state, the first capacitor C ₀ is charged through the first resistor R ₀ , and the control circuit power supply voltage V _C0 rises as shown in FIG. 2 (a).

When the control circuit power supply voltage V _C0 exceeds the upper set value V _L1 at time t ₀ , the switch control circuit CR ₂ operates and the first and second switches S ₁ and S ₂ are shown in FIG. 2 (e). To turn it on. As a result, the first capacitor C ₀ to the resistor R ₂ and the second
Starting current I _S1 as shown in FIG. 2 (c) to the control electrode (base) of the switching element Tr ₁ to flow through the capacitor C ₁ and the second switch S _2, the switching element Tr ₁ is Figure 2 (d ), It is turned on. Second capacitor
As C ₁ is charged, the voltage V _C1 increases and the starting current I _S1 decreases as shown in FIG. 2 (b).

Meanwhile, from the first capacitor C ₀ to the second resistor R ₁ and the first
Current flows through the switch S _{1 of} the first capacitor C ₀
The control circuit power supply voltage V _C0 across both ends of the voltage drops as shown in FIG. 2 (a).

At time t ₁ , the voltage V _C1 changes When the, the starting current flowing through the second capacitor C ₁ to the switching element Tr ₁ longer, is only slightly starting current I _S1 continues to flow through the resistor R ₂ and a discharge element R _3.

At this time, the electric charge of the first capacitor C ₀ is equal to that of the second resistor R ₁
And is continuously discharged through the first switch S ₁ , and the control circuit power supply voltage V _C0 continues to drop thereafter. As a result, discharge starts in the second capacitor C _1, the second capacitor C ₁
The voltage V _C1 starts to fall.

At time t ₂ , when the control circuit power supply voltage V _C0 becomes equal to the voltage V _C1 , the starting current I _S1 becomes zero and the switching element T
r ₁ cuts off as shown in FIG. 2 (d). On the other hand, the first capacitor C ₀ is continuously discharged, and the control circuit power supply voltage
V _C0 continues to decline thereafter. As a result, the reverse bias voltage is applied to the control pole of the switching element Tr ₁ by the second capacitor C ₁ .

At time t ₃ , the control circuit power supply voltage V _C0 is set to the lower set value V _L2.
When the temperature falls below the range, the switch control circuit CR ₂ is activated and the first and second switches S ₁ and S ₂ are, as shown in FIG. 2 (e),
Both are turned off. As a result, the first capacitor C ₀ is charged through the first resistor R ₀ , and the control circuit power supply voltage
V _C0 rises again.

At time t _4, the second discharge of the capacitor C ₁ is completed.

At time t ₅ , the state is the same as at time t _0, and thereafter, at time t ₀
The operation from ˜t ₅ is repeated, so that the pulsed starting current I _S1 is repeatedly supplied to the control pole of the switching element Tr ₁ .

By the above operation, when the switching operation of the switching element Tr ₁ is started and a load current flows in the load circuit LC ₁ , the start / stop circuit ST detects this and the first and second switches S ₁ , forcing will be to turn off the S _2. As a result, the starting current I _S1 to the switching element Tr ₁
Will be stopped. In addition, switching elements
Drive current to the control electrode of Tr _1, since is continuously supplied from the load circuit LC _1, the switching operation of the switching element Tr ₁ lasts without hindrance.

The control circuit CR ₁ controls ON / OFF of the switching element Tr ₁ as in the conventional example.

The inverter device of this embodiment has a control circuit power supply voltage V _C0
Since the repetition cycle of the starting current I _S1 is determined by pulsating the pulse current, a special timer circuit including the voltage response switch element SBS etc. that determines the cycle is unnecessary, and the first resistor for the control circuit power supply is also unnecessary. Since R ₀ and the first capacitor C ₀ are also used for starting, the number of parts is small, and rational and cost reduction can be achieved.

Also, during the period in which the control circuit power supply voltage V _C0 is pulsating,
Since the switching operation of the switching element Tr ₁ is not yet performed and the control circuit CR ₁ is not operating at this time, the pulsating flow of the control circuit power supply voltage V _C0 adversely affects the operation of the inverter device. Never give.

In addition, the starting current I _S1 is supplied to the switching element T through a differentiation circuit composed of a resistor R ₂ and a second capacitor C ₁ in series.
At the same time as supplying to the control pole of r _1, the control circuit power supply voltage V _{C0 serving} as a power supply is lowered, so that the current flowing through the discharge element R ₃ for discharging the second capacitor C ₁ is eliminated and the control of the switching element Tr ₁ is performed. A reverse bias voltage can be applied to the poles. As a result, the width of the pulsed starting current I _S1 can be narrowed. Therefore, even when there is no load, the switching element Tr ₁ does not remain on for a long time, and abnormal oscillation in the load circuit LC ₁ and destruction of the switching element Tr ₁ can be prevented.

In addition, the starting current I is applied to the switching element Tr ₁ through a differentiation circuit composed of a resistor R ₂ and a second capacitor C ₁ in series.
_{Since S1} is flown, the magnitude of the starting current I _S1 can be arbitrarily set by changing the resistance value of the resistor R ₂ , and therefore an appropriate starting current I _S1 is supplied to the control pole of the switching element Tr _1. be able to. As a result, it is possible to prevent the control pole of the switching element Tr ₁ from being destroyed by causing an excessive starting current I _S1 to flow, and it is not necessary to use a _second switch S ₂ having a large current capacity.

The generation cycle of the starting current I _S1 under no load is the value of the first resistor R ₀ , the first capacitor C ₀ and the second resistor R ₁ , and the upper set value V _L1 in the switch control circuit CR ₂ . And the lower set value V _L2 .

In addition, it does not include a component that is difficult to be integrated into a circuit because of its circuit configuration, so that the integrated circuit can be easily formed and the cost can be reduced.

FIG. 3 shows a concrete implementation of the circuit of FIG.
In FIG. 3, the DC power source E performs full-wave rectification on the voltage of the AC power source AC by the diode bridge DB and smoothes it by the smoothing capacitor C ₃ . The load circuit LC ₁ is composed of inductors L ₁ and L ₂ , a capacitor C ₂ , a current transformer CT ₁ and a resistor R ₁₂ ,
An oscillating current is generated by the inductor L ₁ and the capacitor C ₂ and supplied to the load LD such as a discharge lamp through the current transformer CT ₁ and the inductor L ₂ .

The first switch S ₁ is composed of a transistor Tr ₃ and the second switch S ₂ is composed of a transistor Tr ₂ . R
₄ and R ₅ are the base resistances of the transistors Tr ₄ and Tr ₅ , respectively, and D ₁
Is a flywheel diode connected in parallel with the switching element Tr ₁ and ZD ₀ is a zener diode.

The start / stop circuit ST includes a load current detection circuit DT ₁ that detects a load current and a transistor Tr _{4 that is} turned on / off by the load current detection circuit DT ₁ . Then, when the load current is flowing, the output of the load current detection circuit DT ₁ goes high and the transistor Tr ₄ is turned on. The transistors Tr ₂ and Tr ₃ are forcibly turned off. Further, when the load current is not flowing, the output of the load current detection circuit DT ₁ becomes low level, the transistor Tr ₄ is turned off, and the transistors Tr ₂ and Tr ₃ are turned on / off according to the output of the switch control circuit CR _2. .

The switch control circuit CR ₂ includes a comparator IC ₁ and resistors R _{6 to} R.
₁₁ , a transistor Tr _5, and a Zener diode ZD ₁ . In this configuration, the upper set value V _L1 is And the lower set value V _L2 is Becomes However, V _ZD1 is the Zener voltage of the Zener diode ZD ₁ .

Then, when the control circuit power supply voltage V _C0 becomes higher than the upper set value V _L1 , the output of the comparator IC ₁ becomes high level, and the transistors Tr ₂ , Tr ₃ , Tr ₅ are turned on. On the other hand, when the control circuit power supply voltage V _C0 becomes lower than the lower set value V _L2 , the output of the comparator IC ₁ becomes low level and the transistors Tr ₂ , Tr ₃ , Tr ₅ are turned off.

Other circuit operations are as described with reference to FIG.

A second embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 4, this inverter device is of a two-stone half bridge type and intermittently turns on and off the load circuit LC ₁ by alternately turning on and off the two switching elements Tr ₁ and Tr _{6 formed} of transistors. It supplies power.

The load circuit LC ₁ is composed of a load LD such as a discharge lamp and an inductor L ₁
And it is composed of a current transformer CT ₂ and the capacitor C _2, C _4, configuration as that of Figure 3 but slightly different, the inductor L ₁
The point that the oscillating current is generated by the capacitor C ₂ and the capacitor C ₂ and is supplied to the load LD, and the point that the drive current is supplied from the current transformer CT ₂ to the control poles (bases) of the switching elements Tr ₁ and Tr ₆ are the same. D ₂ is a flywheel diode connected in parallel with the switching element Tr ₆ .

The configuration and operation of the other circuit parts are the same as those in FIG. 3, and therefore detailed description thereof will be omitted.

〔The invention's effect〕

According to the inverter device of the present invention, the control circuit power supply voltage is used as a pulsating flow to determine the repeating cycle of the starting current, so that a special timer circuit including a voltage response switch and the like for determining the cycle is unnecessary, and the control is performed. Since the first resistor and the first capacitor forming the circuit power supply are also used for starting, rational and cost reduction can be achieved. Also, the period when the control circuit power supply voltage is pulsating is when the switching operation of the switching element is not yet performed, and at this time, the control circuit for controlling the on / off of the switching element is not operating yet, so The pulsating circuit power supply voltage does not adversely affect the operation of the inverter device.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing the configuration of the first embodiment of the present invention,
FIG. 2 is a time chart showing the operation of the circuit of FIG. 1, FIG. 3 is a circuit diagram showing the concrete constitution of the circuit of FIG. 1, and FIG. 4 shows the concrete constitution of the second embodiment of the present invention. Circuit diagram, fifth
FIG. 6 is a circuit diagram showing the configuration of the conventional example, and FIG. 6 is a time chart showing the operation of FIG. E ... DC power supply, LC ₁ ... load circuit, Tr ₁ ... switch element, R ₀ ... first resistance, R ₁ ... second resistance, R ₃ ... discharge element, C ₀ ... second 1st capacitor, C ₁ ... 2nd capacitor, S ₁ ... 1st switch, S ₂ ... 2nd switch, CR
₁ ...... Control circuit, CR ₂ ...... Switch control circuit

Claims (1)

[Claims] 1. An inverter device including a switching element, which is connected to a direct current power source to generate a high frequency output voltage, comprising: a first resistor and a first capacitor connected to both ends of the direct current power source to form a control circuit power source. A series circuit, a series circuit of a second resistor and a first switch connected to both ends of the first capacitor, and a second circuit connected to both ends of the first capacitor via a control pole of the switching element. 2 capacitors and 2nd
A series circuit of switches, a discharge element that is connected in parallel with the second capacitor to discharge the electric charge of the second capacitor, and if the voltage of the first capacitor exceeds an upper set value, then An inverter, comprising: a switch control circuit that turns on the first and second switches, and turns off the first and second switches when the value is below a lower set value. apparatus.