JPH0251361A - Inverter apparatus - Google Patents

Abstract

PURPOSE:To operated a load stably by providing an inductance having a balancer function with two taps, by connecting each impedance element between each tap and one end of a resonance capacitor, and by reversing their polarities. CONSTITUTION:A discharge lamp lighting device as an inverter apparatus operating a plurality of loads in parallel alternately turns ON and OFF switching transistors(Tr) Q1-Q2 series-connected with both ends of a DC power supply E to convert said DC power supply E into a high frequency one. A resonance capacitor C1 is connected with both ends of said TrQ2 via a choke coil L1 to light discharge lamps DL1, DL2 via inductances L2, L3 having a balancer function. In this case, said inductances L2, L3 are provided with two taps and capacitors C4, C5 are inserted therebetween, while an inductance L4 between said taps is formed in a reversed polarity manner relative to others. Thus, even if any of said discharge lamps DL1, DL2 is unconnected, said loads can be operated stably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an inverter device that operates a plurality of loads in parallel using a current resonance type inverter.

[Prior Art I] As an inverter device that operates a plurality of loads in parallel using a current resonance type inverter, there is a discharge lamp lighting device shown in FIG. In this discharge lamp lighting device, switching transistors Q, ,Q are connected in series to both ends of a DC power source E.
, are turned on and off alternately by the oscillation control circuit 1, and the DC power supply E
A so-called bar 7 bridge imperter is used to convert the frequency to the ^ frequency.

Note that reflux diodes D, D, are connected in antiparallel to both ends of the switching transistors Q, Q2. A resonant capacitor C3 is connected to both ends of the switching transistor Q2 via a chiroke coil L, and a resonant capacitor C3 is connected to both ends of the resonant capacitor C3 via inductances L, , L, which have a parallax function to adjust the lamp current. Discharge lamp DL.

DL2 is connected in parallel. In addition, the discharge lamp DL.

There are preheating capacitors C,,C on the valve power supply side of DL.

are connected to each other.

In this discharge lamp lighting device, the oscillation frequency is controlled by the transistor Q.
Resonant frequency f = 1/2 of the circuit connected to both ends of 2
1+2, a high frequency voltage is generated across the capacitor CI, thereby starting the discharge lamps DL,, DL,. Note that the inductances L2-L3, which have a parallelizer function, are connected so that they have opposite polarities as shown in Figure 6, so when two lamps are connected, the currents flowing through the inductances L, L, and L3 are mutually connected. canceled and has no impedance in steady state.

In this way, the discharge lamps DL, , D1. ．． The equivalent circuit of the circuit connected to both ends of the transistor Q2 when two lamps are installed is shown in FIG.

Note that the resistor R3 is the equivalent resistance of the discharge lamp DL, and the resistor R2 is the equivalent resistance of the discharge lamp DL. In this case, the resonance curve before starting the discharge lamp is a curve with one pole shown by the solid line in FIG. Therefore, if the oscillation frequency of the inverter INV is selected near the resonance point r0 in FIG. 9, a voltage sufficient to start the discharge lamps DL, DL, can be obtained. And discharge lamp D
The voltage across the capacitor CI after L, DL, is lit is:
It becomes as shown by the solid line in FIG. 9(b). In addition, in FIG. 9, the resonance 5α before and after starting of the discharge lamps DL, DI, 2 is shown.
Although shown to match, strictly speaking, the discharge lamp DL,
, DL2 are turned on, the resonance point f0 becomes lower.

In such a discharge lamp lighting device, as shown in FIG. 9(b), the oscillation frequency f1 of the inverter INV is selected at a point in the so-called slow phase mode where the impedance of the circuit is ωL>1/ωC. The reason why the oscillation frequency of the inverter INV is selected at a point where the circuit inverter is in the slow phase mode is as shown in FIG. 10(b), when the collector current Ic of the switching transistors Q, , Q2 is
If the waveform is delayed compared to the collector-emitter voltage VCE shown in Figure 0 (a), the switching transistor Q
This is because it can reduce stress.

In this discharge lamp lighting device, as described above, the inverter rN
By setting the oscillation frequency r1 of V, it is possible to stably light the discharge lamps DL, DL2 during steady lighting, but if one of the discharge lamps DL is not attached or the filament is broken and it does not light up, As shown in FIG. 10(c), the waveform of the collector current Ic is advanced compared to the collector-emitter voltage VCE, and has a steep rise of 9 and a large loss. In other words, the equivalent circuit when one lamp is turned on is shown in FIG. 8, and the resonance white line in this case is as shown by the dashed line in FIG. 9(a).
This is because there are two resonance points f0°tro°. In this case, the switching transistor Q
, ,Q increases, and there is a risk that the switching transistors Q, ,Q, may be damaged. Note that this state similarly occurs when the load is other than a discharge lamp.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and its purpose is to operate the load stably even when one of the loads is disconnected. The purpose of the present invention is to provide an inverter device that can perform the following functions.

[Means for Solving the Problems J] In order to achieve the above object, the present invention connects a resonant capacitor to the power supply side of the load in parallel with the load, and each load has a paralleler function to adjust the load current. In addition to connecting via an inductance, two taps are provided on the inductance, an impedance element is connected between each tap and one end of the resonant capacitor, and the polarity of the inductance between the taps is set to the polarity of the other inductance. It is on the opposite polarity.

(Function) By configuring the present invention as described above, even when one of the loads is disconnected, the inductance having a parancer function can influence the resonant circuit including the inverter load by the impedance element. Try not to
The load can be stably operated even if any of the plurality of loads is disconnected.

(Example) An embodiment of the present invention is shown in FIGS. 1 to 3.

This embodiment will also be explained using a discharge lamp lighting device as an example.

In this embodiment, as shown in Fig. 1, two taps are provided on an inductance having a parancer function, a Chitaak coil is provided, and capacitors C4 and Cg are connected between the connection point with capacitor C3 and each tap. and the inductance between the taps and the polarity of the respective taps and the discharge lamp DL,
, DL2 and the polarity of the dark inductance L, ,L, is opposite to that of the dark inductance L, ,L,. Note that the other configurations are the same as the conventional circuit shown in FIG. 6.

In this discharge lamp lighting device, the discharge lamps D L , DL
#I is the equivalent circuit at the time of starting when both 2 lamps are installed.
In the equivalent circuit of Fig. 2 shown in Fig. J2, the 7th circuit of the conventional example is
Capacitor C4 is connected in series with capacitors C2 and C3 in the diagram circuit.
, C, are connected, but the capacitor C,
, C, are sufficiently larger than capacitors C2 and C3, so the equivalent circuit is essentially the same as the equivalent circuit in Figure 7, and therefore the operation when two lamps are installed is the same as the conventional example. .

Note that in this embodiment as well, the inductances L 2 and L 3
and inductance L4 are connected so that they have opposite polarities, so when two lamps are connected, each inductance is 2.
The currents flowing through ~L4 cancel each other out, so that it has no impedance in a steady state.

Next, a case will be described in which, for example, one of the discharge lamps DL comes off or the filament is broken and the discharge lamp DL becomes unlit. The equivalent circuit in this case is
As shown in FIG. 3, the appearance of the circuit configuration is greatly changed. However, the inductance L3. Since the polarity of L4 is reversed as described above, the total inductance of the inductance L is small.

In other words, the inductance can be made smaller than the inductance L2 in FIG. 8, and the waveform of the collector current Ic when one lamp is lit can be made close to that shown in FIG. 10(b). The inconvenience of entering the phase advance mode is eliminated, and even when one lamp is lit, the discharge lamp DL2 can be lit stably.

Note that by increasing the capacitance of the capacitors C, , C, a better collector current IC waveform can be obtained.

In the following, the circuit connected in parallel with the capacitor C1 in FIG. 3 will be considered in more detail. The impedance Z of this circuit is 1 - once 1 is generally > 0, ω''C,C,C.

ω(L4-C4-Cs) is also >0. Note that since the equivalent resistance R2 is smaller than C, it is ignored.

By the way, in the case of this embodiment, although the inductance of the circuit connected in parallel to the capacitor CI is smaller than that of the conventional case as described above, it still has an inductance as shown in the equation. I understand that. Therefore,
By reducing the influence of this inductance in the following manner, the stress on the switching transistor Q when one lamp or α lamp is used can be further reduced. In other words, ■Equation 2
By making the denominator of the term smaller and the numerator larger, the influence of inductance can be further reduced. In this way, the collector current IC waveform can be further improved.

Note that this method is particularly effective for discharge lamps DL,...
If DL2 is the same wattage (, inductance L 2 t L with a parancer function for optimization of lamp current)
3 is not the same turn, the inductance is different, >
This is a case where L. In addition, on the contrary, inductance! When the inductance of lL3 is L2>L, the inverse single capacitor C4? Let the capacity of Cs be C, > C,
In this way, connect capacitor C41C5 in parallel to the lamp current path, and connect capacitor C41C5 in parallel to the lamp current path.
If the capacitance of the switching transistor Q1.1 is adjusted to cancel the inductance of the inductance L21Ls having a balancer function, the switching transistor Q1. The waveform of the collector current Ic of Q2 can be further improved, and the lamp current when lighting two lamps can also be freely set by using the capacitors C4t and C5 and the inductance L2-Ls.

By the way, in this example, a case has been described in which a check coil is connected to an inductance having a parancer function, and a capacitor C41Cs is connected between the connection point with the capacitor C8 and each tap. The impedance element is not limited to a capacitor as long as it reduces the inductance of the impedance element. The circuit configuration in this case is shown in FIG.

Furthermore, it is not limited to discharge lamp lighting devices that light two lamps in parallel.
A similar effect can be obtained by lighting multiple discharge lamps DL in parallel, such as the three lamps shown in FIG. Furthermore, the inverter circuit is not limited to a separately excited bar 7-ply spring inverter, but can be used as a full-ply spring inverter if it constitutes the above-mentioned resonant circuit. ν
An inverter, a single-stone inverter, a self-excited inverter, an inverter using a rectified and smoothed commercial power source, and a switching element such as an FET or a thyristor may be used.

[Effects of the Invention J] As described above, the present invention connects a resonant capacitor to the power supply side of the load in parallel with the load, and connects each load via an inductance having a paranser function to adjust the load current. Two taps are provided in the above inductance, an impedance element is connected between each tap and one end of the resonant capacitor, and the polarity of the inductance between the taps is set to be opposite to that of the other inductances. Even if the load is disconnected,
The impedance element prevents the inductance, which has a parancer function, from affecting the resonant circuit including the inverter load, and therefore allows the load to operate stably even if one of the multiple loads is disconnected. There is an effect that can be done.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is an equivalent circuit diagram of the main parts when two of the above discharge lamps are installed, and Fig. 3 is a state where one of the above discharge lamps is installed. 4 is a circuit diagram of an embodiment other than 1, FIG. 5 is a circuit diagram of another embodiment, and FIG. 6 is a circuit diagram of a conventional example.
Figure 7 is an equivalent circuit diagram of the main parts when two discharge lamps are installed, Figure 8 is an equivalent circuit diagram of the main parts when one discharge lamp is installed, and Figure 9 is an equivalent circuit diagram of the main parts when two discharge lamps are installed. A characteristic diagram showing a resonance curve, and FIG. 10 are operation waveform diagrams of each part of the same. rNV is an inverter, DL, DL is a discharge lamp, L2~
L is an inductance, and C1 is a resonant capacitor. Agent Patent Attorney Ishi 1) Ai Figure 7, Figure 2 L+ Figure 3, Ll Figure 7, Figure 9, Figure 10

Claims (1)

[Claims] (1) In an inverter device that operates multiple loads in parallel using a current resonance type inverter, a resonant capacitor is connected in parallel to the load on the power supply side of the load, and an inductance has a balancer function to adjust the load current of each load. At the same time, two taps are provided on the above inductance, an impedance element is connected between each tap and one end of the resonant capacitor, and the polarity of the inductance between the taps is opposite to the polarity of the other inductance. An inverter device characterized by polarity.