JPH03167788A - Inverter device - Google Patents

Abstract

PURPOSE:To reduce the peak value of grounding current by connecting No.1 load circuit and No.1 inductor series circuit in parallel to a capacitor, and connecting No.2 load circuit and No.2 inductor series circuit in parallel to a switching element. CONSTITUTION:A series circuitry of a capacitor C1 and a switching element consisting of a diode D1 and a switching element SW1 are connected in parallel to a DC power supply E1. A series circuitry of No.1 inductor L2' and No.1 load circuit l1 are connected in parallel to the capacitor C1, while a series circuitry of No.2 inductor L2'' and No.2 load circuit l2 are connected in parallel to the switching element. This decreases both pos. and neg. peak values of the grounding current Igr, and variation of the ground level is suppressed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inverter device having two load circuits, and is used, for example, as an electronic ballast for lighting two discharge lamps at high frequency. be able to.

[Prior Art] Conventionally, there is a circuit shown in FIG. 13 or 14 as a voltage resonance type single-stone inverter device having two load circuits. The circuit configuration will be explained below. One end of the parallel circuit of the inductor L1 and the capacitor C1 is connected to the first electrode (positive electrode) of the DC power source E1, and the other end of the parallel circuit is connected to the second electrode of the DC power source E through the switching element SW1. The switching element SW1 is connected to the electrode (negative electrode).The switching element SW1 is made of, for example, an NPN} transistor, and when the control voltage vb applied to its control electrode (base) is at the "High" level, the forward current I
c becomes energized, and when the control voltage vb is at the "Low" level, the forward current 1c is blocked. A diode D1 is connected in antiparallel to both ends of this switching element SW1. The drive circuit is powered by a DC power source E. , and generates a control voltage vb to be applied to the switching element SWl.

In conventional example 1 shown in FIG. 13, two load circuits 1. , e2 are connected in parallel. Furthermore, in the conventional example 2 shown in FIG. 14, the switching element S
Two load circuits 1. , 1, are connected in parallel. In either circuit, capacitor C1 and inductor L. , L2 are involved in resonance operation, while capacitor C2 is connected to load circuit 1. , l2 is provided to cut off the direct current component of the current flowing through the capacitors, and the capacitance 1 is set to be large enough not to affect the resonance operation. Load circuit 1. , 12, the capacitor C2 may be omitted if there is no problem even if a certain amount of direct current flows through them.

FIG. 15 and FIG. 16 are operation waveform diagrams of conventional example 1 and conventional example 2, respectively. In each of the above figures, (a) is the control voltage vb applied to the switching element SW1, (b) is the current Ic flowing through the switching element SW1, (c) is the voltage Vce across the switching element SW, and (d) is the load circuit I1. Load current flowing to 11. , (e) is load circuit 1
The load current 12 flowing through the ground line 12 (f) shows the waveform of the current Igr flowing through the ground line.

However, the negative direction current 1c means the current flowing through the diode D1.

The operation of Conventional Example 1 (see FIG. 15) will be explained below. First, when the control voltage vb becomes ``High'' level and the switching element SW is turned on, a current flows from the DC power supply E1 through the inductor L. and the switching element SW1, and from the DC power supply E, the capacitor C2 , the current flows through the load circuits 1., 12, the inductor L2, and the switching element SW1.At this time, the current Ic flowing through the switching element SWI is limited by the inductors L+, L2, so that the current flows over time. As the current Ic increases, energy is accumulated in the inductors I and L2.At this time, the load circuits 1 and 12 have a load current I1.
,, If2 is in the negative direction (opposite direction to the arrow shown in Fig. 13)
The flow is gradually increasing. Further, the capacitor CI is connected to the DC power source E so that the cathode side of the diode D is negative. is charged to the same voltage as the switching element S
The voltage Vce across Wl is zero.

Next, when the control voltage vb reaches the "Low" level and the switching element SW is turned off, the inductor L.
．． Due to the energy stored in L2, the inductor L,
, an electromotive force is generated in the direction in which current continues to flow through L2, and current flows from inductor L2 through capacitor C2 and load circuit 1.12, and current flows through the inductor and capacitor C1 in the same direction. , capacitor C1 has opposite polarity, that is, diode D.
is charged so that the cathode side of is positive. As a result, the voltage Vce across the switching element SW1 increases. At this time, load circuit 1. , 12 is the load current I/I
l2 flows while gradually decreasing in the negative direction.

Next, the charge accumulated in capacitor C1 is transferred to inductor L
2. Load circuit 1. , /2 are discharged through the capacitor C2 and are also discharged through the inductor in the same direction. At this time, load current If. ，
I12 flows while gradually increasing in the positive direction (the same direction as the arrow shown in FIG. 13). When the charge in the capacitor C is completely discharged, the inductors L1 and L2 generate an electromotive force in the direction of continuing current flow, and the inductor L2 generates an electromotive force in the load circuit L2.
12, current flows through capacitor C1 through capacitor C2, and current flows through inductor L. However, current flows through capacitor C1. As a result, the capacitor C1 is charged again to the opposite polarity, that is, the cathode side of the diode D1 becomes negative. At this time, the load current If! ,, [2 flows while gradually decreasing in the positive direction. Further, the voltage Vce across the switching element SW1 decreases and eventually becomes zero. Capacitor CI is DC power supply E! When charged to a voltage higher than the diode D
, becomes conductive, and the load circuit 1. is connected from the inductor L2. ,1,
, the current flows through the capacitor C2, the DC power supply E diode D1, and the DC power supply E also flows from the inductor L.
．． Current flows through diode D. This diode D. The current flowing through is the negative ground current Ig
It flows as r. After that, the switching element SW1 is turned on, so that the current Ic gradually increases again.
flows as the ground current IHr in the positive direction, and the same operation is repeated thereafter. Next, the operation of Conventional Example 2 (see FIG. 16) will be explained. First, when the switching element SW1 is off, the inductors L1, L2,
Load circuit 1. , 12, a current flows through the capacitor C2, and the capacitor C2 is connected to the load circuit l. The battery is charged so that the 12 side is positive. After that, the control voltage vb becomes ゜'H
high” level, and the switching elements SW,
is turned on, the load circuit 1+,
12, the inductor L2, and the switching element SW1, and at the same time, a current flows from the DC power supply E1 through the inductor L1 and the switching element SW1.
Since the current Ic flowing through the switching element SW I is limited by the inductors L, L2, the current gradually increases. At this time, load circuits 1, 1 . is the load current I/
,, [2 is flowing while gradually increasing in the negative direction (the opposite direction to the arrow shown in FIG.
The flow gradually increases in the positive direction (in the same direction as the arrow shown in Figure 14) through the . Also, capacitor C1 is diode D
It is charged to the same voltage as the DC power supply E so that the cathode side of I becomes negative, and the voltage Vce across the switching element SW1 is zero.

Next, when the control voltage vb reaches the "Lo1 level" and the switching element SW + is turned off, the inductor L
．． L2 generates an electromotive force in the direction in which current continues to flow, so current flows from inductor L2 through capacitor C DC power supply E1, capacitor C2, and load circuit 11.12, and at the same time flows from inductor L1 to capacitor C in the same direction.
A current flows through 1. As a result, the capacitor C1 is charged with reverse polarity, that is, with the cathode side of the diode D1 being positive.

Therefore, the voltage Vce across the switching element SW1 increases. In addition, load circuit i. , 12 has a load current I
Z. , IN2 are gradually decreasing in the negative direction.

In addition, the ground current Igr is the load current Il,,I12
Therefore, the flow gradually decreases in the negative direction.

Next, the charge accumulated in capacitor C1 is transferred to inductor L2, load circuit l. 12, capacitor C2, DC power supply E
1 and the inductor L in the same direction.
1 is also discharged. At this time, load circuit 1, j! 2 has a load current I1 in the positive direction and in the same direction as the arrow in FIG.
,H! 2 flows gradually increasing, and both load currents IN. ,Il
The sum of 2 becomes the ground current Igr. When the charge in capacitor C1 is completely discharged, inductors L, L2 generate an electromotive force in the direction of continuing current flow, and inductor L2
From load circuit 1. , 12, capacitor C2, DC power supply E
, , a current flows through the capacitor C1, and a current flows in the same direction from the inductor L1 to the capacitor C1. Therefore, capacitor C+ is charged again with reverse polarity, that is, with the cathode side of diode D becoming negative. At this time, load circuit 1. , 12 has a positive load current IN■1
2 flows gradually decreasing, and both load currents 11. ．． The sum of Il2 becomes the ground current Igr. Further, the voltage Vce across the switching element SW drops. When capacitor C, is charged to a voltage higher than the voltage of DC power supply E1, diode D1 becomes conductive, causing load circuit 1. , 12, a current flows through the capacitor C2 and the diode D1, and the inductor L. From DC power supply E
1. Negative ground current Ig via diode D1
r flows. However, since this ground current Igr flows only due to the residual energy of the inductor L1, it is small enough to be ignored. Thereafter, the switching element S W + is turned on, so that the ground current Igr in the positive direction that gradually increases flows again, and the same operation is repeated thereafter.

[Problems to be Solved by the Invention] In the above-mentioned conventional example 1, the current Ic flowing through the switching element SWl directly becomes the ground current Igr, so that the peak value of the current Ic immediately before the switching element SW+ turns off However, the problem is that the positive peak value of the ground current Igr is high because it flows directly to the ground line. On the other hand, in Conventional Example 2, at the moment the switching element SW is turned off, the back electromotive force (so-called kick voltage) generated by the inductor L2 is applied to the DC power supply E1 via the capacitor C1, and the negative ground Since it flows as current Igr, there is a problem that the negative peak value of ground current Igr is high. As described above, in Conventional Example 1.2, the peak value of the ground t current Igr flowing through the ground line is high, so the line impedance existing on the actual circuit (for example, the resistance component on the wiring pattern of the electric wire or printed circuit board) ) becomes larger.

As a result, the following problems arise.

■The ground level fluctuates greatly, making circuit operation (especially control circuit operation) unstable.

■Due to the resistance component R of line impedance, R --
Power equivalent to I Fir2 is consumed, circuit loss is large, and efficiency is reduced.

■The noise level increases due to high-frequency fluctuations in the ground level.

■Since the peak value of the ground current Igr is high, the reliability of circuit components including electric wires and printed circuit boards decreases.

The present invention has been made in view of these points, and its purpose is to reduce the peak value of ground current when driving two load circuits with a resonant single-stone inverter device. to suppress ground level fluctuations,
The aim is to solve each of the above problems. [1000 Steps to Solve the Problems] Figure 1 is a circuit diagram showing the basic configuration of the present invention. In this circuit, switching element SW1 and diode D
A series circuit of a switching element consisting of 1 and a capacitor C1 is connected in parallel to a DC power source E1, a series circuit of a first load circuit l1 and a first inductor L2' is connected in parallel to the capacitor C1, A series circuit of a second load circuit 12 and a second inductor L2'' is connected in parallel to the switching element.

FIG. 2 is a circuit diagram showing another basic configuration of the present invention. In this circuit, the load circuit 11, which was connected in parallel to the load circuit l2 in the conventional example shown in FIG. It also serves as the above-mentioned l-th and second inductors L2', L2''. Note that the capacitor C
2 is for DC cut and does not affect the resonance operation, so if the load circuit l2 can be driven with DC, capacitor C2
may be omitted. Further, since the inductor L constitutes a closed circuit with the capacitor C1, it is hardly related to the ground current IHr, and the operation of the present invention is not affected even if the inductor L is not present. However, inductor L1
If is omitted, the charging and discharging speed of the capacitor CI changes, so the resonant frequency changes.

[Function] Hereinafter, the function of the present invention will be explained based on FIGS. 3 and 4. FIG. 3 is an operational waveform diagram of the circuit shown in FIG. 2.

Further, FIGS. 4(a) to 4(d) show the operation of the circuit shown in FIG. 2 divided into four stages. First, when the switching element SW1 is turned on, a gradually increasing current flows from the DC power supply E1 through the inductor L1 and the switching element SW1, as shown in FIG. 4(a). In addition, the DC power supply E
1 to load circuit l. The load current I1!1 flows through the inductor L2 and the switching element SWl while gradually increasing in the negative direction (in the direction opposite to the arrow in FIG. 2). Since the sum of these currents flows to the ground line, the ground current Igr
is a current that gradually increases in the positive direction (the same direction as the arrow in FIG. 2). In addition, from the DC cut capacitor C2 to the load circuit 12, the inductor L2, and the switching element S
A load current I1'2 flows through W1 while gradually increasing in a negative direction (in a direction opposite to the arrow in FIG. 2). Since this negative igi' current I122 does not flow to the ground line, the positive peak value of the ground current Igr is lower than in the conventional example 1. Since the switching element SW1 is turned on, the capacitor C1 is charged to the same voltage as the DC power supply E1 so that the cathode side of the diode D1 becomes negative, and the voltage VCe across the switching element SW1 becomes zero. There is.

Next, when the switching element SW is turned off, the inductors L + and L2 generate an electromotive force in the direction of continuing current flow, so that the inductor L2 is connected to the capacitor c1, as shown in FIG. DC power supply E capacitor C
2. The load current 12 flows through the load circuit 12 while gradually decreasing in the negative direction, and the load current 11. flows gradually decreasing in the negative direction. Furthermore, current flows from the inductor L1 to the capacitor c1 in the same direction. This results in
The capacitor c1 is charged with the opposite polarity, and the cathode side of the diode D1 becomes positive. In this process, the voltage Vce across the switching element SW increases. Note that since the load current IN2 flows through the ground line, the ground current IH
r flows while gradually decreasing in the negative direction (in the opposite direction to the arrow in FIG. 2).

Next, the charge accumulated in the capacitor C1 is
), it is discharged from capacitor C1 to inductor L2, load circuit l2, capacitor C2, and DC power supply E1.
The load current I12 gradually increases in the positive direction {the same direction as the arrow in FIG. 2} through the capacitor C1, the inductor L2, and the load circuit 1l.
The current flows in the positive direction (the same direction as the arrow in FIG. 2) while increasing gradually, and the current also flows in the same direction from the capacitor CI to the inductor.

When the charge in the capacitor C1 is completely discharged, the inductors L, L2 generate an electromotive force in the direction of continuing the current flow, and the inductor L2, the load circuit 12, the capacitor C2,
Load current I12 via DC power supply E1 and capacitor C.
flows in the positive direction while gradually decreasing, and the inductor L2
The load current I is passed from the load circuit l1 to the capacitor C1.
l. flows gradually decreasing in the positive direction. Furthermore, current flows in the same direction from the inductor L1 to the capacitor C1.
As a result, the capacitor C1 is charged again in the opposite direction, that is, so that the cathode side of the diode D1 becomes negative.

In this process, the voltage Vce across the switching element SW drops.

Next, when the voltage of the capacitor C1 is charged to a voltage higher than the voltage of the DC power supply E1, the diode D becomes conductive, and as shown in FIG. As the load current 112 gradually decreases in the positive direction through C2 and diode D1,
From inductor L2 to load circuit l1, DC power supply E1, diode D. The load current IN. flows gradually decreasing in the positive direction. Further, a current flows from the inductor L1 via the DC power supply E1 and the diode D.

After that, when the switching element SW1 is turned on, the fourth
Returning to the initial process shown in Figure (a), the same operation is repeated.

In the process shown in Fig. 4(c), the load current 12 flows to the ground line, so when the charge in the capacitor CI is being discharged, the ground current 1gr flows gradually increasing in the positive direction, and the capacitor c1 flows in the opposite direction. When charged with polarity, the ground current Igr flows in the positive direction while gradually decreasing.

Then, when the process in Figure 4(c) shifts to the process in Figure 4(d), and the load current I12 begins to flow through the diode D, the ground current Igr will flow in the negative direction. .

After all, in the present invention, the ground current Igr flowing through the ground line immediately before switching element SW1 is turned off is only the current flowing through inductor L1 and load circuit l1, and does not include the current flowing through load circuit 12. do not have.
Therefore, the positive peak value of the ground current Igr is lower than that of the first conventional example.

Immediately after the switching element sw is turned off, the current due to the electromotive force (kick voltage) generated in the inductor L2 is fed back to the direct a power supply E1 as a negative ground current Igr via the load circuit 12. It is also shunted to circuit 11. Therefore, the negative peak value of the ground current Igr is also lower than in the second conventional example. Therefore, both the positive and negative peak values of the ground current Igr become low, and fluctuations in the ground level are suppressed, thereby solving each of the above-mentioned problems (1) to (2). The above explanation of the operation is such that the inductor L2 shown in FIG. 2 is connected to the first and second inductors L2', as shown in FIG.
Needless to say, the same holds true even if the capacitor C1 is arranged separately in the switching element S W +.The same principle applies when the capacitor C1 is connected in parallel to the switching element SW In addition, in conventional example 2 shown in FIG. 14, the load current 11.
Since the sum of Il2 flows to the DC cut capacitor C2, the amplitude of the current flowing to the capacitor C2 is large as shown in FIG. 17(a). However, in the structure of the present invention shown in FIG. Only Il2 flows through the DC cut capacitor C2, and the load current I1 does not flow through the DC cut capacitor C2.
As shown in b), the amplitude of the current flowing through capacitor C2 becomes smaller.

Therefore, the dielectric loss (loss caused by tan δ) of the capacitor C2 can be reduced.

[Embodiment 1] Figure 5 is a circuit diagram of the first embodiment of the present invention. In this embodiment, the AC power source is full-wave rectified to obtain the DC power source E1. The alternating current voltage of the alternating current power supply AC is connected to the diode D2~
It is full-wave rectified by a diode bridge consisting of D5,
It is smoothed by capacitor C and converted to DC voltage. The capacitor C is set to have a large capacitance so as not to affect the LC resonance. switching element S
As Wl, an NPN} transistor is used, and a diode D is connected in antiparallel between its collector and emitter. As the first load circuit l, a lighting load is used in which a capacitor C4 for supplying a pre-warming current is connected in parallel between the non-power supply side terminals of the filament of a hot cathode discharge lamp La+. Further, as the second load circuit 12, a lighting load is used in which a capacitor C5 for supplying preheating current is connected in parallel between the non-power supply side terminals of the filament of the hot cathode discharge lamp Laz. Furthermore, when one discharge lamp starts, it increases the lamp voltage of the other discharge lamp to help start.
Balancer transformer B1 is connected to load circuit l. It is connected between 12. The circuit configuration of the pond is the same as the basic i-precept shown in Figure 2. Capacitor for preheating current supply C. , C, and the balancer transformer B1 are connected to the discharge lamp La. , La2 has almost no effect on the circuit operation, except for a change in the resonance frequency. Therefore, as explained with respect to the basic configuration shown in FIG. 2, the peak value of the ground current is reduced and fluctuations in the ground level are suppressed. [Embodiment 2] Figure 6 is a circuit diagram of a second embodiment of the present invention. In this embodiment, a power MOS is used as the switching element Q1.
FET is used. Therefore, the anti-parallel diode parasitic between the drain and source is replaced by the diode D1 mentioned above.
The anti-parallel diode is not externally connected. In addition, both load circuits have a resistance R
+, R2, the capacitor C2 for DC cut is omitted. Furthermore, capacitor C1 is connected in parallel with switching element Q.

[Example 3] FIG. 7 is a circuit diagram of a third embodiment of the present invention.

The difference from the basic configuration shown in FIG. 2 is that the switching element consisting of the switching element SW and the diode D1 is
The capacitor C and the inductor L1 are connected to the opposite side of the parallel circuit, and the DC cut capacitor C2 is connected between the first load circuit l and the second load circuit e2. It is a point. [Embodiment 4] FIG. 8 is a circuit diagram of a fourth embodiment of the present invention.

In this embodiment, a transformer T1 is used in place of the inductors L, L2 in the basic configuration shown in FIG. This transformer T. is a leakage transformer equivalent to a circuit composed of inductors L1 and L2 when inductor L2 is considered as an excitation inductance. In addition,
In a general single-stone inverter device using a transformer, it is not necessary to connect the primary side and the secondary side of the transformer, but in this embodiment, the positive electrode side of the DC power source E1 is connected.

The reason for this is that if the primary and secondary sides of the transformer T1 were not connected, there would be no path for current to flow through the load circuit 12. [Embodiment 5] FIG. 9 is a circuit diagram of a fifth embodiment of the present invention. In this embodiment as well, a leakage transformer T1 is used as in the above-mentioned embodiment 4, but the fourth embodiment differs in that the primary side and the secondary side are connected on the side of the switching element SWl. This is different from . Further, the inductor L2 is connected in series with the load circuit e2.

Without this inductor L2, the switching element SW,
No power is supplied to load circuit l2 during the on period of . [Embodiment 6] FIG. 10 is a circuit diagram of a sixth embodiment of the present invention.

In this implementation, the capacitor C is the switching element SW.
1, and the inductor L2 is connected in parallel with the load circuit 1.
．． , l2 flows through the inductor L2'', and the load current of the load circuit 12 flows through the inductor L2''.

[Example 7 FIG. 11 is a circuit diagram of a seventh embodiment of the present invention.

In this embodiment, capacitor C. ,C. A series circuit of " is connected in parallel to the DC power source E1.

[Example 8 FIG. 12 is a circuit diagram of an eighth embodiment of the present invention.

In this embodiment, an inductor L is connected in parallel with the load circuit 11 to bypass direct current from flowing through the load circuit 11.

[Effects of the Invention] According to the present invention, as described above, in a resonant single-stone inverter device that drives two load circuits, the peak value of the ground current flowing through the ground line can be reduced. It can increase the reliability of circuit components, reduce power consumption in line impedance, improve circuit efficiency, and suppress ground level fluctuations, which stabilizes circuit operation. This has the effect of reducing the noise level.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first basic configuration of the present invention, FIG. 2 is a circuit diagram showing a second basic configuration of the present invention, FIG. 3 is an operation waveform diagram of the same as above, and FIG. ) to (d) are circuit diagrams for explaining the operation of the above, FIG. 5 is a circuit diagram of the first embodiment of the present invention, FIG. 6 is a circuit diagram of the second embodiment of the present invention, and FIG. 7 is a circuit diagram of the second embodiment of the present invention. FIG. 8 is a circuit diagram of the fourth embodiment of the present invention, FIG. 9 is a circuit diagram of the fifth embodiment of the present invention, and FIG. 11 is a circuit diagram of the seventh embodiment of the present invention, FIG. 12 is a circuit diagram of the eighth embodiment of the present invention, FIG. 13 is a circuit diagram of the first conventional example, 14th
The figure shows the circuit diagram of the second conventional example, Fig. 15 shows the operating waveforms of the first conventional example, Fig. 16 shows the operating waveforms of the second conventional example, and Figs. 17(a) and (b) show the operating waveforms of the second conventional example. 2A and 2B are diagrams showing the waveforms of the current flowing through the DC cut capacitor in the second conventional example and the present invention, respectively. E1 is a DC power supply, SWl is a switching element, D is a diode, CI is a capacitor, 11 is a first load circuit, 1
2 is the second load circuit, L2° is the first inductor, L2
” is the second inductor.

Claims (4)

[Claims] (1) A series circuit of a switching element and a capacitor that controls opening/closing of forward current but does not block reverse current is connected in parallel to a DC power supply, and a series circuit of a first load circuit and a first inductor is connected to the capacitor. An inverter device characterized in that a series circuit of a second load circuit and a second inductor is connected in parallel to the switching element. (2) The inverter device according to claim 1, wherein the first inductor and the second inductor are shared. (3) The inverter device according to claim 1, wherein at least one of the first and second inductors is an excitation inductance of a transformer. (4) A parallel circuit of a switching element and a capacitor that controls opening/closing of forward current but does not block reverse current is connected in parallel to a DC power supply via a series circuit of a first load circuit and a first inductor. . An inverter device, characterized in that a series circuit of a second load circuit and a second inductor is connected in parallel to the switching element.