JPS60255067A - One-element type inverter - Google Patents

Abstract

PURPOSE:To reduce the loss of a main transistor by inhibiting the supply of a base current of the transistor until the voltage between the collector and the emitter of the transistor crosses zero. CONSTITUTION:A series circuit of a capacitor 71 and a diode array 2 is connected with between both terminals of feedback winding 31f of an output transformer 31 so that diode array 72 becomes the same polarity as the base and the emitter of a main transistor 32, and a transistor 73 is connected in series with the base drive circuit of the transistor 32. A drive controller having a transistor 74 and diodes 75, 76 for turning ON the transistor 73 only when the array 72 generates a positive voltage is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a single-stone inverter used, for example, in a discharge lamp lighting device.

(Background of the Invention) FIG. 3 does not show the circuit configuration of a discharge lamp lighting device using a conventional base feedback type single-stone inverter. In the same figure, 1
is an AC power source such as a commercial power source, and a rectifier, such as a rectified circuit 2, is connected to this AC power source 1, and a 1G blocking oscillation type transistor inverter 3 is connected between the rectifier output terminals a and b of the rectifier circuit 2. , Furthermore, this inverter 3
A discharge lamp (lamp) 4 as a load is connected to the secondary winding 31s of the output transformer 31. 5 is a high frequency bypass capacitor, which may also be used as a smoothing capacitor in a capacitor input type rectifier circuit.

The inverter 3 includes an output transformer 31Jg, a main transistor 32, etc., and connects the output 1 to the transformer 31 between the positive output terminal a of the rectifier circuit 2 and the collector of the transistor 32.
This primary winding 3 is connected to the primary winding 31+1 of
A resonance capacitor 33 is connected in parallel with 1p, and the 1st capacitor of the transistor 32 is connected to the negative side output terminal (common terminal) b of the rectifier circuit 2 via the diode 34, and the collector of the transistor 32 and the rectifier circuit 2 are connected in parallel. A diode 35 is connected between the negative side output terminal and the transistor 32 and the diode 3.
The base feedback winding 31f of the output transformer 31 has one end connected to the negative output terminal of the rectifier circuit 2 (l!!1 is connected to the capacitor 36 and the inductor 37). The emitter and collector of a transistor 391 are connected to both ends of the capacitor 36 via a diode 392, and the base of this transistor 391 is connected to an output transistor. The base feedback winding 31f of No. 31 is connected to a terminal wound up on the other end side.

Note that the diode 34 is used to protect the transistor 32 from reverse voltage between the base and emitter, and to supply the base extraction current in just the right amount.

In addition, when the transistor 32 is A), the die A-de 35 connects the transistor 32 to the output 1 to the primary winding 31p of the lance 31.
This is a damper diode that prevents distortion of the output waveform by providing a current path in the opposite direction to the collector current. Further, the transistor 391, the diode 392, etc. are used to set the capacitor 36 to discharge when the transistor 32 is turned off and the base feedback winding voltage becomes negative, so that a discharging resistor is connected in parallel with the capacitor 36. Q reduction of the LC resonant circuit and transistor 3 due to
This prevents deterioration of the switching characteristics of 2.

Next, the operation of the discharge lamp lighting device constructed as above will be described.

When AC power supply 1 is turned on, full-wave rectifier circuit 2 generates a full-wave rectified output (pulsating output), which is applied to inverter 3 . As a result, in the inverter 3, the rectified output is applied as a base current to the transistor 32 via the bias resistor 38, and the transistor 32 is turned on. Thereafter, the transistor 32 is connected to a collector-base positive feedback loop consisting of the primary winding 31p of the collector output transformer 31 of the transistor 32, the base remote winding 31f, the capacitor 36, the inductor 37, the base of the transistor 32, etc. Oscillation occurs due to the inductance of the next winding 31ρ and the resonance of the capacitor 33, and each winding llA31p of the output 1 to the lance 31.

A high frequency output is generated at 31s and 31f. lamp 4
is given a high frequency output through the secondary winding 31s of the output transformer 31 and is turned on.

By the way, in this inverter 3, the capacitor 36
By supplying a base current to the transistor 32 through the series circuit of the inductor 31 and the inductor 31, the high frequency switching characteristics are improved. That is, the capacitor 36 and the inductor 37 form a series resonant circuit, and the positive current provides sufficient drive to the main transistor 32, and the negative current draws out a large base charge.
This base extraction current is caused by the action of the diode 34.
That is, at the moment when the main transistor is turned off, the collector current of the main transistor 32 becomes equal to the base extraction current, so that when the diode 34 is turned off, it stops, and excess or deficiency is prevented. However, even with such measures, the switching loss of the main transistor 32 was not reduced as much as expected.

As a result of various studies on the causes of this, the present inventors have found that the collector-emitter voltage VCe of the transistor 32 and the feedback winding 31f of the output transformer 31, as shown in the voltage and current waveform diagrams in FIG. The waveform is almost the same as that of the induced voltage (hereinafter referred to as drive voltage) Vf, but since the drive voltage Vf is induced so that its average value is zero, the reference potential (0 level position) is different. Therefore, even in a positive section before the collector-emitter voltage VCO crosses zero, the drive voltage Vf crosses zero and becomes a positive voltage, resulting in a section [1] in which the base voltage of the transistor 32 becomes positive, and this section At t1, the transistor 32 is turned on even though the base current ib flows and the voltage vCe has not yet crossed zero. For this reason, the transistor 32 consumes the energy of the resonant circuit of the capacitor 33 and the quadrature primary winding 31p, and it has been found that the switching loss when the transistor 32 is turned on increases.

Figure 5 shows the circuit configuration of a discharge lamp *J device devised based on the above knowledge and previously filed for patent application No. Sho 58-157945 by the present applicant. , 3rd
In contrast to the one shown in the figure, a transistor 61 as a switching element is connected between the base of the main transistor 32 of the inverter 3 and the negative output terminal of the rectifier circuit 2, and a feedback winding between the base of the transistor 61 and the output transformer 31 is connected. line 3
A series circuit of a capacitor 63 and a zener diode 64 is connected between the base terminal of It is connected. Note that the diode 62 is similar to the diode 34 for the transistor 32, and the diode 62 is for the transistor 61.
The diode 65 is used for resetting the capacitor 63 together with the transistor 391.

In this inverter 3, by applying to the base of the transistor 61 a portion of the voltage obtained by differentiating the electric currents H, V f induced in the feedback winding 31f by the capacitor 163, which exceeds the Zener voltage of the Zener diode 64, to the base of the transistor 61. A section including a section 11t1 in which the drive voltage vf is positive even though the slope of the drive voltage V [is positive and is larger than a certain value, that is, the voltage between the rector and emitter of the transistor 32] remains sufficiently. During t2, the transistor 61 is turned on and the base current Ib of the transistor 32 is bypassed. As a result, the transistor 32 operates in a period t3 after the collector-emitter voltage Vce crosses zero.
Only the base current is supplied to turn it on, reducing switching loss.

However, in the single-stone inverter of this prior application, when the input voltage, that is, the output voltage of the rectifier circuit 2 decreases, the drive t
Since ir-tvr also decreases, there is a disadvantage that the effect of reducing switching loss of the main transistor 32 decreases.

(Objective of the Invention) An object of the present invention is to always enable a sufficient reduction in switching costs (especially at turn-on) in a base feedback single-stone blocking inverter, regardless of input voltage fluctuations.

(Structure of the Invention) In order to achieve the above object, the present invention (“is an output transformer having a primary winding and a feedback winding;
- a base feedback single-stone blocking inverter, which drives the base of the main transistor by a current supplied from the feedback winding via an LC series resonant circuit, the base feedback single-stone blocking inverter comprising: a main transistor; A constant voltage element that generates a constant voltage, and a switching circuit that enables supply of base drive current from the feedback winding to the main transistor according to the voltage between the terminals of the constant voltage element. It is characterized by having been established.

(Explanation of Examples) The present invention will be described in detail below with reference to the drawings.

Note that parts common or corresponding to those of the conventional example are represented by the same reference numerals.

FIG. 1 shows a circuit configuration of a discharge lamp lighting device according to an embodiment of the present invention. The device shown in the figure is different from the one shown in FIG. 3 by connecting a series circuit of a capacitor 71 and a diode array 72 between both terminals of the WI winding 31F so that the diode array 72 has the same polarity as the base and emitter of the transistor 32. The transistor 13 is connected in series to the base drive circuit of the transistor 32, and the transistor 74 is connected in series to the base drive circuit of the transistor 32.
, diodes 75, 76, etc., and a drive control circuit that turns on the transistor 13 only when a positive voltage is generated in the diode array 72.

Note that the capacitor 71 is a level shift (coupling)
The diode 75 is for protecting the transistor 14 from the base-to-litter reverse voltage caused by the feedback winding 31. In addition, the diode 77 is connected to the feedback winding 3.
This is for bypassing the base draw current of the transistor 32 by 1f.

Next, the operation of the device shown in FIG. 1 will be explained with reference to the voltage and current waveform diagrams at various parts shown in FIG.

When the AC power supply 1 is turned on, a full-wave rectifier output (pulsating output) is generated from the full-wave rectifier circuit 2, which is applied to the inverter 3, which causes the inverter 3 to oscillate as described above, generating a high-frequency output. The lamp 4 lights up.

However, in this inverter 3, the feedback winding 31f
The positive voltage is level-shifted by the capacitor 71 and then rectified by the diode array 12, and the nearly constant voltage and period forward voltage generated in the diode array 72 is applied to the transistor 74.In other words, the diode array 12 As shown in FIG. 2, a voltage Vd obtained by slicing the trapezoidal drive voltage ffVt by the voltage VC of the capacitor 72 and having a timing approximately equal to the on-time of the transistor 32 is obtained between the terminals of the transistor 32, as shown in FIG. By changing according to the human power voltage, the voltage vd becomes a nearly constant voltage for a fixed period regardless of the human power voltage and the drive voltage, so the transistor 74 and therefore the transistor 73 are driven with a constant base current only for a certain period. Therefore, the base drive current to the transistor 32 is supplied at almost the same timing as the on-time of the transistor 32, regardless of the input voltage and the drive voltage, reducing the turn-on loss of the transistor 32. - This switching improvement effect does not change even if the input voltage changes.

It should be noted that the present invention is not limited to the embodiments described above, but can be modified as appropriate without departing from the spirit of the present invention.
I can do it. For example, the inverter 3 rectifies a part of the output and stores it in a condenser, and the rectifier circuit 2
C may also be applied to a so-called auxiliary power type inverter that supplies the inverter 3 as an auxiliary horn while the rectified output of the capacitor is lower than the voltage across the capacitor, and in this case, the diode 35 can be omitted. Also, instead of connecting the pnD transistor 73 in series with the base circuit of the +1- transistor 32, as shown in FIG.
The npn transistor 78, which is turned off when the main transistor 4 is turned on, may be connected in parallel with the base circuit of the main transistor 32.

In this case, the diode 11 becomes unnecessary.

Further, in the figure, a diode 19 and a capacitor 80 at J3 constitute a piezoelectric power source for driving the base of the transistor 18.

As described above, according to the present invention, the switching circuit prohibits the supply of base current to the main transistor until the voltage between the rector and the 1-mitter of the main transistor of the inverter crosses zero, thereby improving the turn-on loss of the main transistor. In addition, since the switching circuit is controlled by a fixed-period, constant-voltage signal obtained by level-shifting the drive voltage, turn-on loss is minimized, with little influence on circuit operation due to fluctuations in the input voltage and thus the drive voltage. An improved circuit can be realized. This reduces loss in the main transistor, improves circuit efficiency, and reduces heat generation in the main transistor. Particularly, for example, in an inverter circuit using a partial smoothing circuit, the effect of improving turn-on loss is not impaired even if the output voltage of the smoothing circuit is low.

[Brief explanation of drawings]

Fig. 1 is a partial circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention, Fig. 2 is a voltage or current waveform diagram of each part of the discharge lamp lighting device of Fig. 1, and Figs. 3 and 5. is a circuit diagram of a discharge lamp lighting device using a conventional single-stone inverter, FIGS. 4 and 6 are voltage or current waveform diagrams of various parts of the discharge lamp lighting device shown in FIGS. 3J3 and 5, respectively, and FIG. FIG. 3 is a partial circuit diagram of a discharge lamp lighting device according to another embodiment. 1...AC power source, 2...Aftermath rectifier circuit, 3...
Inverter, 31... Output transformer, 30... Base feedback winding, 32... Main transistor, 3G...
Conf'Ij137...Inductor, 71...Diode array, 72...Capacitor, 73, 74...
...Transistor. Patent applicant Toshiba Electric Materials Co., Ltd. agent Patent attorney Ito Torigumi agent Patent attorney Tetsuya Ito

Claims (1)

[Claims] 1. An output transformer having a primary winding, a feedback winding, and a main transistor that energizes the primary winding, and a current supplied from the feedback winding through a TC series resonant circuit. In the base feedback single-stone blocking inverter that drives the base of the main transistor, a constant voltage circuit generates a constant voltage output only during a predetermined period when the induced voltage of the feedback winding is 1, and the constant voltage output 1. A single-stone inverter comprising: a switching circuit for enabling base drive current to be supplied from the feedback winding to the main transistor. 2. The single-stone inverter according to claim 1, wherein the constant voltage I-circuit is formed by connecting a level shift I-capacitor and a plurality of diodes in series.