JPH0623197U - Inverter device - Google Patents

Abstract

(57) [Abstract] [Purpose] Detecting OFF of a self-excited switching element in an inverter device in which one of two switching elements connected in series to a DC power supply is self-excited and the other is separately excited. To improve the detection circuit for realizing stable operation. [Structure] In order to detect the off state of a transistor Q ₁ driven by self-excitation, in parallel with one of voltage dividing series resistors R ₄ , R ₅ connected in parallel to both ends of a transistor Q ₂ driven by another excitation. A capacitor C ₇ was connected to form a differentiating circuit. [Effect] A small change in the voltage across the transistor Q ₂ can be detected greatly, and therefore an ON signal of the transistor Q ₂ driven separately can be reliably generated, and a stable oscillation operation can be continued.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an inverter device, and is used, for example, in a discharge lamp lighting device for lighting a discharge lamp at a high frequency.

[0002]

[Prior art]

FIG. 3 shows a circuit diagram of a conventional inverter device (see Japanese Patent Laid-Open No. 63-297276). The circuit configuration will be described below. First and second transistors Q ₁ and Q ₂ as switching elements are connected in series between both ends of the DC power source E ₁ . Diodes D ₁ and D ₂ are connected in antiparallel to the transistors Q ₁ and Q ₂ , respectively. A load circuit Z including a series circuit of an inductor L ₁ and a load F ₁ such as a discharge lamp is connected to both ends of the transistor Q ₁ via a coupling capacitor C ₀ for cutting a DC component. Feedback means FB ₁ for feeding back the secondary winding n ₂ of the vibration current only inductor L ₁ to the control terminal of the I the first transistor Q ₁ flowing through the load circuit Z is provided, at a predetermined cycle determined by the oscillating current Only transistor Q ₁ is on / off controlled. n ₁ is a primary winding of the inductor L ₁ , and C ₁ is a resonance capacitor.

In this circuit, the second transistor Q ₂ is turned on during the timer operation period of the timer circuit 3 by the timer circuit 3 activated in response to the turning off of the transistor Q ₁ , and the timer of the timer circuit 3 is turned on. There is provided a control means X which is turned off after the operation is completed. In the control means X shown in FIG. 3, the detection circuit 1 detects the off time of the transistor Q _1. At this off time, the trigger circuit 2 triggers the timer circuit 3 to start the timer operation. By the timer output of the timer circuit 3, the transistor Q ₂ is turned on for a certain period of time, and then the transistor Q ₂ is turned off. In this case, the on-duty (length of on-period) of the transistor Q ₂ can be changed according to the time constant of the timer circuit 3, so that the output of the inverter device can be adjusted and the load F is released. If it is a light, it can be dimmed.

FIG. 4 is a circuit diagram showing a specific configuration of the circuit of FIG. Since the basic configuration of the inverter device is the same as that of the conventional example shown in FIG. 3, parts having the same functions are designated by the same reference numerals, and redundant description will be omitted. In FIG. 4, the resistor R ₁ is the base resistance of the transistor Q ₁ , and the resistor R ₂ is the base resistance of the transistor Q ₂ . This inverter device has a starting circuit ST ₁ for starting the oscillating operation of the transistors Q ₁ and Q ₂ when the power switch SW is turned on and the DC power source E ₁ is turned on. The starting circuit ST ₁ is the power-on, the capacitor C ₂ is charged through the resistor R _3, the the charging voltage reaches the breakover voltage of the two-terminal thyristor Q _3, two-terminal thyristor Q ₃ is turned on, flowing a base current to the base of the transistor Q ₂ through a two-terminal thyristor Q _3, initially operates on-the transistors Q _2, activate the inverter device. D ₃ is a diode, which discharges the electric charge of the capacitor C ₂ through the transistor Q ₂ after the activation of the inverter device and stops the operation of the activation circuit ST ₁ .

The transistor Q ₂ is on / off controlled by a monostable multivibrator MV ₁ which constitutes the trigger circuit 2 and the timer circuit 3 in FIG. This monostable multivibrator MV ₁ is composed of a general-purpose integrated circuit (for example, μPD4538 manufactured by NEC Corporation), and is an output terminal for a certain period of time after the falling trigger input terminal B changes from high level to low level. Q becomes high level and output terminal Q'becomes low level, and the states of output terminals Q and Q'invert after a lapse of a certain time. In this example, by dividing the collector-emitter voltage V ₂ of the transistor Q ₂ in the series circuit of a resistor R _4, R ₅ connected in parallel to a transistor motor Q _2, to detect the off-Tran register Q _1, single It is used as the trigger signal for the stable multivibrator MV ₁ . This constitutes the detection circuit 1 of FIG. Monostable multivibrator rater MV ₁ of the output terminal Q becomes a high level time (the output terminal Q 'have time to become low level) is determined by the time constant of the resistor R ₆ and the capacitor C _3.

The output terminal Q of the monostable multivibrator MV ₁ is connected to the base of a driving transistor Q ₄ via a resistor R ₇ , and the output terminal Q ′ is connected to a driving transistor Q ₅ via a resistor R _8. Connected to the base of. The collector of the transistor Q ₄ are the positive electrode of the dc power source E _2, the emitter of the transistor Q ₅ is their respective connected to the negative electrode of the DC power source E _2. The emitter of the transistor Q _{4 and} the collector of the transistor Q ₅ are connected to the base of the transistor Q ₂ via the resistor R ₂ . Therefore, the monostable multivibrator MV ₁ operates as a timer circuit for determining the ON period τ ₁ of the transistor Q ₂ . The monostable multivibrator MV ₁ can continuously adjust the output by changing the value of the resistor R ₆ for setting the time constant, and enables continuous dimming when the load F is a discharge lamp. Become. Incidentally, V _1, V ₂ the transistors Q _1, Q collector-emitter voltage of _2, I _1, I ₂ Waso respectively transistors Q _1, the collector current of Q _2, Id _1, Id ₂ each diode The regenerative current flowing through D ₁ and D ₂ and Vbe ₂ are the base-emitter voltage of the transistor Q ₂ .

FIG. 5 is an operation waveform diagram of each part of the inverter device when the load circuit Z is inductive. FIG. 3A shows an oscillating current I 2 flowing as a load current in the inductor L ₁ , in which I ₁ and I ₂ are collector currents flowing in the transistors Q ₁ and Q ₂ , and Id ₁ and Id ₂ are diodes D respectively. shows the regenerative current flowing to _1, D _2. Further, FIG. (B) the collector-emitter voltage V ₁ of the transistor Q _1, to FIG. (C) the collector-emitter voltage V ₂ of the transistor Q _2, FIG. (D) shows the transistor Q ₁ base The emitter-to-emitter voltage Vbe ₁ , the output signals of the output terminals Q and Q'of the monostable multivibrator MV ₁ are shown in (e) and (f) of the figure, and the base current Ib _{1 of the} transistor Q ₁ is shown in (g) of the figure. Are shown respectively.

The operation of the inverter device of FIG. 4 will be described below with reference to the operation waveform diagram of FIG. When the power switch SW is turned on, the transistor Q ₂ is first turned on by the start-up circuit ST ₁ , and the collector-emitter voltage V ₂ (see FIG. 5 (c)) becomes low level. Therefore, the monostable multivibrator is used. The falling trigger input terminal B of MV ₁ changes from high level to low level. As a result, the monostable multivibrator MV ₁ is triggered and its output terminal Q becomes high level and its output terminal Q ′ becomes low level (see FIGS. 5E and 5F). Accordingly, transistor Q ₄ for driving on, the transistor Q ₅ is turned off, the DC power source E ₂ from the transistor Q _4, a base current is supplied to the transistor Q ₂ through the resistor R _2, the on-state transistor Q ₂ is maintained To be done. When the transistor Q ₂ is turned on, the diode D ₃ becomes conductive and the capacitor C ₂ is no longer charged, so that the starting circuit ST ₁ stops operating. In this case, the secondary winding n ₂ of the inductor L ₁ is wound on the polarity so as to apply a reverse bias voltage between the base and emitter of the bets transistor Q _1, the transistor Q ₁ is kept off.

Next, after a lapse of a predetermined time determined by the resistor R ₆ and the capacitor C ₃ , the output terminal Q of the monostable multivibrator MV ₁ becomes low level, the output terminal Q ′ becomes high level, and the transistor Q ₄ becomes Off, transistor Q ₅ turns on. Therefore, the transistor Q ₂ is turned off. When the transistor Q ₂ is turned off at the point P shown in FIG. 5A, the collector current I ₂ of the transistor Q ₂ decreases, and the residual inductance of the inductor L ₁ generates an opposite induced voltage. At this time, the oscillating current I flowing through the inductor L ₁ tends to flow in the same direction, so that the diode D ₁ becomes conductive and the current Id ₁ flows. Further, by the secondary winding n ₂ of the inductor L ₁ generates a reverse induced voltage, as shown in FIG. 5 (d), base-emitter voltage Vbe ₁ of the transistor Q ₁ is a positive The transistor Q ₁ is forward biased, and the transistor Q ₁ is turned on. When the current Id ₁ in the diode D ₁ becomes zero, the transistor Q ₁ is the collector current I ₁ flows through the charge accumulated in the capacitor C ₀ as the power source. At this time, the core of the inductor L ₁ is linearly magnetized toward the saturation magnetic flux. When the core reaches the saturation magnetic flux, the inductance of the inductor L ₁ suddenly moves toward zero, and as a result, the time change of the collector current I ₁ of the transistor Q ₁ becomes infinite.

Transistor Q₁Collector current I₁At time Ta (see FIG. 5 (g)), the base current is multiplied by hfe (I₁= Hfe × Ib₁) Is reached, the transistor Q ₁ Becomes unsaturated and inductor L₁Each winding n₁, N₂Since the induced voltage of is reduced, the feedback base current Ib₁Also decreases (see Fig. 5 (g)), transistor Q₁Is reverse biased. After that, transistor Q₁After the oscillating current flows for the storage time Ts of₁Turns off. Transistor Q ₁ Inductor L after turning off₁Since the oscillating current I flowing in the diode D tends to flow in the same direction, the diode D₂Conducts and current Id₂Is load circuit Z and capacitor C₀, DC power supply E₁Flow on the route. Diode D₂Is turned on, the transistor Q₂Collector-emitter voltage V₂Is zero, the monostable multivibrator MV₁The falling trigger input terminal B of changes from high level to low level again, and the monostable multivibrator MV₁Output terminal Q goes high, driving transistor Q_FourIs turned on and transistor Q₂Is forward biased. Diode D₂Current Id flowing in₂DC power source E₁ Capacitor C₀, Load circuit Z, transistor Q₂Collector current I ₂ Flows. Hereinafter, by repeating the above-mentioned operation, the oscillation of the inverter device is continued.

In the conventional example shown in FIG. 4, the input signal Vb to the falling trigger input terminal B of the monostable multivibrator MV ₁ is started from the falling time of the collector-emitter voltage V ₂ of the transistor Q _2. There is always a delay in the timing of. For this reason, when the period during which the diode D ₂ is conducting becomes short, a large power supply short-circuit current flows from the DC power supply E _{1 in} the path of the diode D ₁ and the transistor Q ₂ , and the transistors Q ₁ and Q ₂ Stress increased and in some cases could be destroyed. Therefore, as shown in FIG. 6, there is _one in which voltage-dividing capacitors C ₇ and C ₈ are used in place of the voltage-dividing resistor connected in parallel with the transistor Q ₂ for detecting the off state of the transistor Q ₁ (Japanese Patent Application No. -199943).

Further, the transistor Q₁If the voltage waveform at the time of turning off is blunt, the transistor Q ₂ At the moment when the drive signal is input to the transistor Q₁May be connected to the DC power supply E₁To transistor Q₁, Q₂A large short-circuit current flows to the transistor Q₁, Q₂The stress on the vehicle will increase and in some cases it may be destroyed. In order to prevent this, as shown in FIG._FiveIn parallel with capacitor C₈There is also an example of inserting.

[0013]

[Problems to be solved by the device]

In the conventional example of FIG. 4 and FIG. 6, the collector-emitter voltage V ₂ of the transistor Q ₂ is divided by a resistor or a capacitor to detect the fall of the collector-emitter voltage V ₂ , and thus the transistor Q ₁ The off time is detected and used as the trigger signal for the monostable multivibrator MV ₁ . However, in the conventional example shown in FIG. 4 and FIG. 6, when the DC power supply E ₁ has a voltage lower than usual due to some influence, for example, the commercial power supply is full-wave rectified When the power source E ₁ is used, the following problems occur when the commercial power source experiences a momentary power failure or a momentary voltage drop. In other words, when the DC power source E ₁ becomes lower than the normal voltage, becomes close to the waveform of the collector current I ₁ of transistor Q ₁ is in phase, also exists junction capacitance diode D ₂ and transistor Q ₂ and the like Therefore, there is a problem that the regenerative current does not flow in the diode D ₂ , the trigger signal of the monostable multivibrator MV ₁ is not input, and the oscillation cannot be maintained.

This will be described with reference to FIGS. Normally, it operates on the resonance curve of Fig. 9, but DC power supply E₁When the voltage of the load Q decreases, the equivalent resistance value of the load F increases, and the resonance curve of FIG. 9 shifts to the operation. ₂ , Diode D₂The current flowing through the junction capacitance of the DC power supply E has a waveform as shown in FIG.₁When the voltage of is lowered, the waveform becomes as shown in FIG. FIG. 8A shows a transistor Q.₁Collector current I₁And diode D₁Regenerative current Id₁8B shows the transistor Q₂Collector current I₂And diode D₂Regenerative current Id₂8C shows the current Ic of the junction capacitance. FIG. 8D shows a transistor Q.₂Collector-emitter voltage V₂8 (e) is a monostable multivibrator MV.₁The input signal Vb to the falling trigger input terminal B of is shown. Time t₀And transistor Q₁Is turned off, the inductor L₁Since the oscillating current I flowing in the capacitor tries to continue flowing, first, the discharge current Ic of the junction capacitance flows, and accordingly the collector-emitter voltage V₂Begins to fall. Monostable multivibrator MV₁The input signal Vb to the falling trigger input terminal B of the₂Begins to fall at the same rate as. If normal, then diode D₂Regenerative current Id₂Flows, the voltage V₂And Vb should drop to 0V, but transistor Q₁Collector current I ₁ Is close to in-phase, diode D₂Regenerative current Id₂By the time inductors start flowing₁A reverse current starts flowing to the input signal Vb and the monostable multivibrator MV₁The trigger signal does not come in because it does not fall to the trigger level of₁And transistor Q₂No ON signal is input to. That is, the transistor Q₂ON signal is not input to the transistor Q₂Is off, inductor L₁, Diode D₁, Capacitor C₀An oscillating current flows in the path of the load circuit Z. Next, capacitor C₀, Transistor Q₁, Inductor L₁, Load circuit Z, capacitor C₀ Although an oscillating current flows through the path of, the above repetition becomes a damped oscillation and eventually stops the oscillation.

The present invention has been made in view of the above circumstances, and an object of the present invention is to drive one of the first and second switching elements connected in series to a DC power supply in a self-excited manner. In an inverter device in which the other is driven separately, it is intended to improve the detection circuit for detecting the OFF of the switching element driven by self-excitation to realize stable operation.

[0016]

[Means for Solving the Problems]

 In the present invention, in order to solve the above problems, as shown in FIG.₁A first and a second transistor Q between both terminals of₁, Q₂Connected in series with the first and second transistors Q₁, Q₂The first and second diodes D respectively₁, D₂Are connected in anti-parallel, and the first transistor Q₁Inductor L between both terminals of ₁ And capacitor C₁Series circuit and the capacitor C₁A load circuit Z including a load F connected in parallel with the capacitor C for coupling₀And connects the oscillating current flowing in the load circuit Z 1 to the first transistor Q 1.₁Is fed back to the control terminal of the first transistor Q at a predetermined cycle determined by the oscillating current.₁Multi-vibrator MV that detects and turns off and activates₁The second transistor Q during the timer operation period of the timer circuit such as₂And the second transistor Q is turned on after the timer operation of the timer circuit is completed.₂In the inverter device provided with the control means X for turning off the first transistor, the first transistor Q₁Turns off the second transistor Q₂Series resistor for voltage division R connected in parallel with_Four, R_FiveWhen the voltage value at the connection point of the second transistor Q is detected to be above or below a predetermined value, the second transistor Q₂The control means X is configured to generate an ON signal of the voltage dividing series resistor R_Four, R_FiveCapacitor C in parallel with₇ Is connected to form a differentiating circuit.

Instead of the transistors Q ₁ and Q ₂ , MOS transistors, SI thyristors or the like may be used, and generally any semiconductor switching element may be used.

[0018]

[Action]

 In the circuit of FIG. 1, a transistor Q driven by self-excitation is used.₁Transistor Q driven separately to detect the off state of₂Voltage dividing series resistor R connected in parallel at both ends of _Four , R_FiveCapacitor C in parallel with₇Since the differential circuit is formed by connecting₂It is possible to detect a small change in the voltage across the transistor Q, and therefore the separately driven transistor Q₂The ON signal of is surely generated, and stable oscillation operation can be continued.

[0019]

【Example】

An embodiment of the present invention will be described with reference to FIG. In this inverter apparatus, in the resistance R _4, the series circuit of R ₅ for the partial pressure, in parallel with the resistor R ₄ is a capacitor C ₇ that insert, the voltage obtained at the connection point of the resistors R ₄ and R ₅ Is configured to detect the turning-off of the _first transistor Q ₁ . Other configurations are similar to those of the inverter device of FIG.

FIG. 2 is an operation waveform diagram of this embodiment. FIG (a) shows the regenerative current Id ₁ in the collector current I ₁ and the diode D ₁ of the transistor Q _1, FIG. (B) is Trang register Q ₂ collector current I ₂ and the diode D ₂ of the regenerative current Id ₂ is shown, and the same figure (c) shows the current Ic of the junction capacitance. 6D shows the collector-emitter voltage V ₂ of the transistor Q ₂ , and FIG. 8E shows the input signal Vb to the falling trigger input terminal B of the monostable multivibrator MV ₁ .

The operation of this embodiment will be described below. Time t₀And transistor Q₁Is turned off, inductor L₁Since the oscillating current flowing in the transistor tries to continue flowing, first, the discharge current Ic of the junction capacitance flows, and accordingly, the transistor Q₂Collector-emitter voltage V₂And monostable multivibrator MV₁The input signal Vb of the falling trigger terminal B starts to fall. Here, in the circuit of FIG. 1, the voltage dividing resistor R _Four , R_FiveIn the series circuit of_FourIn parallel with capacitor C₇Is inserted, the transistor operates as a differentiating circuit, and the transistor Q₂Collector-emitter voltage V₂The input signal Vb changes greatly with respect to a slight change in Therefore, the input signal Vb is a monostable multivibrator MV.₁To the trigger level of transistor Q₂Generates an ON signal. Therefore, time t₁And transistor Q₂Is turned on and the DC power supply E₁, Capacitor C₀, Load circuit Z, inductor L₁, Transistor Q₂, DC power supply E₁An oscillating current flows through the path. In this way, as in the conventional example, the monostable multivibrator MV₁It is possible to prevent the discharge lamp as the load F from being extinguished without maintaining the oscillation because the trigger signal is not input to.

[0022] In addition, the time t ₁ after, transistor Q ₂ is turned off at time t _2, time t ₂ and later the transistor Q ₁ is turned on, the operation of the transistor Q ₁ is turned off at time t _3, Fig. This is the same as the conventional example shown in FIG.

[0023]

According to the present invention, the turning-off of the first switching element is detected by the series circuit of the resistors connected in parallel to the second switching element, and the series circuit of the resistors is used to configure the differentiating circuit. Since the capacitor is connected in this way, a slight voltage change in the voltage across the second switching element can be detected significantly. Therefore, even if the DC power supply has a voltage lower than that under normal conditions due to some influence, oscillation can be maintained, and stable operation can be realized.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an operation waveform diagram of an embodiment of the present invention.

FIG. 3 is a block circuit diagram showing a schematic configuration of a conventional example.

FIG. 4 is a circuit diagram of a first conventional example.

FIG. 5 is an operation waveform diagram of a first conventional example.

FIG. 6 is a circuit diagram of a second conventional example.

FIG. 7 is a circuit diagram of a third conventional example.

FIG. 8 is an operation waveform diagram of a second conventional example.

FIG. 9 is a diagram showing characteristics of a resonance circuit of a second conventional example.

FIG. 10 is an operation waveform diagram of a main part of a second conventional example.

[Explanation of symbols]

Q ₁ , Q ₂ transistor D ₁ , D ₂ diode R ₄ , R ₅ voltage dividing resistance C ₀ , C ₁ capacitor C ₇ capacitor MV ₁ monostable multivibrator E ₁ DC power supply F load X control means Z load circuit

Claims (1)

[Scope of utility model registration request] 1. A series circuit of first and second switching elements is connected between both terminals of a DC power source, and first and second diodes are respectively connected in antiparallel to the first and second switching elements, A series circuit of an inductor and a capacitor is connected between both terminals of the first or second switching element, and a load circuit including a load connected in parallel to the capacitor is connected through a coupling capacitor, and vibrations flowing in the load circuit. The second switching element is turned on during the timer operation period of the timer circuit in which the current is fed back to the control terminal of the first switching element and the turning-off of the first switching element is detected and activated at a predetermined cycle determined by the oscillating current. And an inverter device provided with control means for turning off the second switching element after the timer operation of the timer circuit is completed. To detect that the voltage value at the connection point of the voltage-dividing series resistor connected in parallel to the switching element is a predetermined value to detect the OFF of the first switching element, and to generate the ON signal of the second switching element. An inverter device characterized in that the control means is configured in the above, and a differential circuit is formed by connecting a capacitor in parallel with one of the voltage dividing series resistors.