JPH0449865A - Inverter device - Google Patents

Abstract

PURPOSE:To start an inverter circuit surely even if instantaneous service interruption occurs by providing a starting circuit with an impedance element, which restrains the high frequency voltage being applied to the control terminal of a switching element by the secondary winding of an oscillating transformer from being added is a trigger element. CONSTITUTION:An impedance element, which restrains the high frequency voltage applied by the secondary windings l2 and l3 of an oscillating transformer T2 from being added to a trigger element Q3, is provided in a starting circuit 2. And, hereby it becomes hard for the high frequency voltage, which is applied to the control ends of switching elements Q1 and Q2 during the residual oscillation period of an inverter circuit 1 at instantaneous service interruption, etc., to be applied to the trigger element Q3, and the trigger element Q3 can be shifted quickly into off condition at the time of instantaneous service interruption. Hereby, the inverter circuit 1 can be started surely by the starting circuit 2 at the time of recovery from instaneous service interruption, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an inverter device that converts a DC voltage into a high-frequency voltage. [Prior Art 1] This type of self-excited inverter device is shown in Fig. 4. Shown below. This inverter device includes an inverter circuit 1 that converts a DC voltage obtained by full-wave rectification of a commercial power source Vs with a diode BRITSUNO DB into a high-frequency voltage, and this inverter circuit 1 includes:
Capacitor C for voltage division at the output of the guide bridge DB
,,C, and transistors Q, ,Q2 are connected in series, capacitor C5°C2 and transistor Q 3 = Q
The primary winding of the output transformer T, which is connected to the load LfJt on the secondary side, and the primary winding 11i 1 + of the oscillation transformer T2 are connected in series between the respective connection points of the oscillating transformer T2.
, 02nd volume 411 z −1, as transistor Q, ,Q
It has a so-called half-bridge configuration in which the bases and emitters of the two transistors are connected through resistors R, , R, respectively.

Furthermore, this inverter device includes a startup circuit 2 that turns on a transistor Q2 to start the inverter circuit 1 when the power is turned on, and this startup circuit 2 includes a capacitor that is charged via a resistor R1 with a diode pre-7D DB output. C5
and a bidirectional trigger element Q such as an SBS that turns on when the voltage across the capacitor C3 reaches the breakover voltage.
, when transistor Q2 turns on, capacitor C3
and a diode D that discharges the charged charge.

If the power is turned on now, the capacitor C9C2 is first charged by the output of the diode preamplifier DB, and the capacitor C3 is charged via the resistor R1. Then, when the voltage across the capacitor C2 reaches the breakover voltage of the trigger element Q, the trigger element Q,
is turned on, a base current is supplied to the transistor Q2 by the charge in the capacitor C1, and the transistor Q is turned on.

When the transistor Q2 is turned on by the starting circuit 2 as described above, the charge accumulated in the capacitor C2 is transferred to the primary winding of the output transformer T1 and the one large winding @1 of the oscillation transformer T2. , transistor Q2 and resistor R2. At this time, a voltage is induced in the secondary winding l of the oscillation transformer T2 in the direction of turning the transistor Q2 into a deeper ON state.
Since positive feedback is applied, the ON state of the transistor Q2 rapidly becomes deeper, and the discharge current of the capacitor C2 increases. Then, as the charge in the capacitor C2 decreases, one large turn #11 of the oscillation transformer T2. When the current flowing through li1. The polarity of the voltage induced in the transistor Q2 is reversed, and a reverse bias is applied to the transistor Q2, turning it off.

On the other hand, when the polarity of the induced voltage in the secondary winding lllAl is reversed as described above, the transistor Q is turned on in the two large windings*12 that are wound in the opposite direction to the secondary @ wire l. A voltage in the direction is induced, and transistor Q1 is turned on. At this time, the electric charge charged in the capacitor C is transferred to one large winding eli of the transistor Q7 and the oscillation transformer T with the resistor R.
i + and the primary winding of the output transformer T, and at this time, the voltage induced in the secondary winding 12 of the oscillation transformer T causes positive feedback to be applied to the transistor Q1, and the discharge current of the capacitor C5 will continue to increase. and,
When the charge in the capacitor C1 decreases and the discharge current begins to decrease, the polarity of the voltage induced in the secondary winding 12 of the oscillation transformer T2 is reversed, and the transistor Q is reverse biased and turned off. . In this case, transistor Q2
is turned on, and the above operation is repeated from then on.

By operating the inverter device in this manner, an alternating current flows through the primary winding of the output transformer T, and a voltage appropriately converted to a voltage by the output transformer T is applied to the load Z.

Note that when the power is turned on, the transistor Q is activated in the startup circuit 1.
2 is turned on, the charge in the capacitor C1 is discharged through the diode D1, the transistor Q2, and the resistor R2, and during the off period of the transistor Q2, the charge in the capacitor C1 is discharged through the diode D1, the transistor Q2, and the resistor R2.
3 is shorter than the voltage across the trigger element Q that reaches the breakover voltage of the trigger element Q, once the inverter circuit 1 starts oscillating, no base current is supplied from the starting circuit 2 to the transistor Q2.

By the way, the above-mentioned inverter device is supplied with a so-called pulsating voltage obtained by full-wave rectification of the commercial power supply Vs by a Guiod Pritzno DB, and the voltage dividing capacitors C,
, C, is small, the output voltage becomes Ov every cycle of the commercial power supply Vs, and therefore, when the output voltage becomes OV, the oscillation operation of the inverter circuit temporarily stops. However, in this way, the inverter circuit 1
When the oscillation stops, the transistor Q2 is turned on by the starting circuit 2 in the same way as when the power is turned on as described above, so the inverter circuit 1 is restarted, and the inverter circuit 1
As long as power is supplied, the oscillator will continue to oscillate.

[Problems to be Solved by the Invention] By the way, in the startup circuit 2 having the above-mentioned configuration, the commercial power supply Vs
In order to supply starting current to the transistor Q2 when the diode pre-, di-DB output rises from the zero cross of the commercial power supply Vs, the trigger element Q is turned off until the next cycle. However, if a momentary power outage occurs before the next cycle, the trigger element Q may not turn off, causing the inverter circuit 1 to stop oscillating.

Below, the cause of the above oscillation stop will be explained using the trigger element Q.
will be explained according to FIG. 5 along with the switching operations of .

Note that FIG. 5 is a circuit diagram of a main part when a silicon pirated switch (SBS) is used as the trigger element Q, and shows the SBS equivalently.

Now, when the power supply VDD is turned on and the voltage across the capacitor C5 charged via the resistor R1 reaches the sum of the base-emitter voltage of the internal transistor d and the zener voltage of the zener diode d, the transistor q1 When the voltage across resistor rl reaches the base-emitter voltage of transistor q2, transistor q2 also turns on, and as a result, capacitor C
A base current of the transistor Q2 which activates the inverter circuit 1 by the photoelectric charge of 5 is supplied via the t+)f element Q. Thereafter, the inverter circuit 1 enters a stable oscillation state. In addition, in the stable oscillation state of this inverter circuit 1, a drive power supply Vd, which is a frequency power supply for alternately switching the transistors Q, is connected between the base of the transistor Q2 and the ground. state, and the internal transistor Q+yQ2
Since the switching characteristics are poor, once the trigger element Q is turned on, it is in an on state in which current continues to flow in both directions by the drive power supply Vd.

Then, when the current flowing through transistor q1 decreases in direct current terms, the voltage across resistor r1 also decreases, and transistor q
As the base-emitter voltage of transistor 2 decreases, it is no longer possible to ensure the on state of transistor q2, and transistor q turns off, and accordingly, transistor q also turns off.
turn off violently.

Now, if an instantaneous power outage occurs while the inverter circuit 1 is oscillating normally, the inverter circuit 1 will oscillate due to the residual charge in the capacitor CI t C2 after the instantaneous power outage occurs. continues. Even during this residual oscillation period, the trigger element Q is kept in the on state by the drive power supply Vd, as described above.

Next, when this instantaneous power outage recovers, the power supply voltage VDD rises sharply, and the flefter current of the transistor Q2 tends to increase accordingly. However, at this time, the trigger element Q is on, so the impulse current as at startup is not supplied to the transistor Q2, and at this time, the power supplied from the drive power supply Vd during residual oscillation is also weak. Because of this, the base current of transistor Q2 is insufficient and a sufficient flipter current cannot flow.
Eventually, the transistor Q2 turns off, and the oscillation of the inverter circuit 1 stops. In this way, once the oscillation of the inverter circuit 1 has stopped, the power supply voltage VDD is smoothed by the voltage dividing capacitors C, , C (however, since the capacitance of the capacitors C, , C is small during normal oscillation, The DC current continues to flow through the trigger element Q via the resistor R1, and the inverter circuit 1 continues to stop oscillating. Incidentally, a phenomenon similar to that described above also occurs due to chattering when the power switch is turned on.

The present invention has been made in consideration of the above-mentioned fish, and its purpose is to provide an inverter device that can easily start an inverter circuit even if a momentary power outage occurs.

[! f! Means for Solving the Problem 1 In order to achieve the above object, the present invention applies a bulk frequency voltage applied by a secondary winding of an oscillation transformer to a control terminal of a switching element turned on by a starting circuit to a trigger element. The starting circuit is provided with an impedance element that suppresses this.

[Function] As described above, the present invention provides an impedance element in the startup circuit that suppresses the high-frequency voltage applied by the secondary winding of the oscillation transformer from being applied to the trigger element, so that the inverter circuit can be activated during instantaneous power outages. During the residual oscillation period, the high frequency voltage applied to the control end of the switching element is applied to the trigger element, so that the trigger element can be quickly turned off even in the event of a momentary power outage. , the inverter circuit can be reliably started by the starting circuit when recovering from a momentary power outage or the like.

Embodiment 1 FIG. 1 shows an embodiment of the present invention. This embodiment has the same basic configuration as the conventional impark device shown in FIG. , a diode Ds is connected in series with the trigger element Q of the starting circuit 2.If the diode D6 is inserted in series with the trigger element Q, for example, the remaining power in the inverter circuit 1 during a momentary power outage can be reduced. During the oscillation period, the trigger element Q does not remain on due to the high frequency power supplied from the oscillation transformer T2, and the trigger element Q quickly shifts to the off state.For this reason, when the momentary power outage recovers, the transistor Q2
An impulse-like base current similar to that at power-on can be supplied to the inverter circuit 1, and the inverter circuit 1 can be actually started.

FIG. 2 is a diagram showing another embodiment of the present invention. In this embodiment, a diode D @ is connected in parallel with a trigger element Q. In this embodiment, when a momentary power outage occurs, The high frequency power supply supplied to the trigger element Q during the residual oscillation period of the inverter circuit 1 is bypassed by the diode D, so that the trigger element Q is quickly turned off even in the event of a momentary power outage.

FIG. 3 shows still another embodiment, in which a capacitor C1 is used in place of the diode Da in FIG. 2 to bypass the high frequency power supply so that the tri-gamma element Q is quickly turned off in the event of a momentary power outage. It's one thing.

[Effects of the Invention] As described above, the present invention provides an impedance that suppresses the application of the high frequency voltage applied by the secondary winding of the oscillation transformer to the trigger element of the switching element turned on by the startup circuit. Since the element is provided in the starting circuit, the high frequency voltage applied to the control terminal of the switching element is difficult to be applied to the trigger element during the residual oscillation period of the inverter circuit during a momentary power outage, etc. Also, the trigger element can be quickly shifted to the off state, and the inverter circuit can be reliably started by the starting circuit when recovering from a momentary power outage or the like.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of one embodiment of the present invention, Fig. 2 is a circuit diagram of another embodiment, Fig. 3 is a circuit diagram of still another embodiment, and Fig. 4 is a circuit diagram of a conventional example. ! FIG. 5 is a main circuit diagram for explaining the reason why the oscillation of the inverter circuit stops during a momentary power outage. 1 is an inverter circuit, 2 is a starting circuit, Q,,Q. is a transistor, Q is a transistor connected to the transistor N1, D is a diode, C, , C2 are voltage dividing capacitors, C, , C, are capacitors, R4 is a resistor, Z is a load, T is an oscillation transformer, l , is the primary winding, 12. l'3 is a secondary winding, DB is a guiode pritzno, and Vs is a commercial power supply. Agent Patent Attorney Ishi 1) Chief Figure 7 5

Claims (1)

[Claims] (1) Two voltage dividing capacitors and two switching elements are connected in series to the output of a rectifier that rectifies commercial power, and oscillation is generated via a load circuit between the connection points of the voltage dividing capacitors and switching elements. When the voltage across the inverter circuit connected to the primary winding of the transformer and the capacitor charged via the resistor by the output of the rectifier at startup reaches the breakover voltage of the trigger element, the trigger element is turned on and the capacitor is charged. and a starting circuit that supplies a starting current that turns on one of the above switching elements using the charged charge of the switching element. A current is passed through the primary winding of the oscillation transformer through the circuit, and at this time, a voltage induced in the secondary winding provided for each switching element of the oscillation transformer is applied to the control terminal of each switching element. In an inverter device that alternately turns on and off each switching element to supply an alternating current to a load circuit, two oscillation transformers are connected to the control terminals of the switching elements that are turned on in the startup circuit.
An inverter device characterized in that an impedance element is provided in a starting circuit to suppress application of a high frequency voltage applied by a secondary winding to a trigger element.