JPH02174565A - Inverter - Google Patents

Abstract

PURPOSE:To reduce the size of an inverter by coupling a rash current limiting inductance inserted into a closed loop comprising a DC current source, a capacitor element and a switching element electromagnetically with an inductance element for limiting load current connected in series with a load. CONSTITUTION:Winding n1 of an inductance element L4 for limiting rash current is inserted into a closed loop circuit comprising a DC current source E1, a capacitor element C1 and a switching element Q1. If the switching element Q1 is turned ON before the voltage VCE to be applied onto the switching element Q1 returns to zero because of the operating conditions of the circuit, peak value of the rash current flowing through the closed loop can be suppressed through the inductance component of the winding n1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inverter device used to operate a discharge lamp as a load at high frequency, for example.

[Traditional techniques]

FIG. 6 is a circuit diagram showing the configuration of a conventional single-stone inverter device.

In FIG. 6, El is a DC power supply, and Ql is a switching element made of, for example, a transistor, which is periodically turned on and off according to a control signal (a rectangular wave signal) given from a control circuit CR. L D is a load such as a discharge lamp, and L2 is a load current limiting inductance element that limits the load current 11 degrees. Power is intermittently supplied via the notching element Q1.

C3 is the load LD when the switching element Q1 is off.
, and the load current limiting inductance element L2, which serve as a conduction path for the oscillating current in the series circuit, and constitute a closed loop circuit with the switching element Q1 and the DC type #E1. Ll is an inductance element connected in parallel with the capacitance element C1, and Dl is a diode connected in antiparallel to the switching element Q1.

This single-stone inverter device consists of switching elements Q,
By turning on and off, high frequency power is supplied to the load 1-D via the load current limiting inductance elements I and 2.

The operation of this circuit will be explained below.

When the switching element Q is turned on by the rectangular wave signal for on/off output from the control circuit CR, the DC power source E1 - the load LD, - the load current limiting inductance element L2 - the switching element Q, - the DC power 'aE1 Current flows through the path.

After that, when the switching element Q is turned off, the negative @
I-D, and inductance element L for limiting load current
The current that was flowing through the series circuit of 2 will continue to flow thereafter, and this current will flow through the capacitance element C1 and charge will be accumulated in the capacitance element C1. The charge stored in the capacitance element C1 is
Discharge occurs through the series circuit of the load L D and the load current limiting inductance element L2, and a high-frequency oscillating current flows through the load L D . Further, the current flowing through the capacitance element C1 also becomes an oscillating current. Therefore, the voltage applied across the switching element Q1 also becomes an oscillating voltage.

As a result of the above-described operation, when the control signal V output from the control circuit CR becomes a rectangular wave signal as shown in FIG. r: is the current I that changes as shown in FIG. 7 (8) and flows through the switching element Q1.

changes as shown in FIG. 7 (bl), the load current IL changes as shown in FIG. 7 (cl), and the current flowing through the capacitance element C1 changes as shown in FIG. 7 (dl).

In the above-mentioned inverter device, when the capacitance element C1 is charged to the voltage of the DC power supply E1, the voltage applied to the switching element Q1, which constitutes a closed loop circuit with the DC power supply E1 and the capacitance element C1, becomes zero; When the switching element Q1 is turned on by the control signal ■3, no current flows from the capacitance element C to the switching element Q1, and only the current flows through the series circuit of the load L D and the load current limiting inductance element L2. It will flow into the switching element Q1.

In this case, the current I of the switching element Q1. As shown in FIG. 7fbl, no rush current flows.

However, depending on the operating state of the inverter device, the capacitance element C1 is not charged to the voltage of the DC power supply E, and the voltage applied to the switching element Q1 is 2. In some cases, the control signal (3) becomes high and the switching element Q1 is turned on without returning to zero. In this case, when the switching element Q1 is turned on, the capacitance element C
A rush current flows that charges the voltage of DC power supply E1 to the voltage of DC power supply E1. The current waveform of the switching element Q1 at this time is shown in FIG. 8(b). In addition, the 81st
ffi(al, (cl, (d), ie) indicate the waveforms at the same locations as +al, (c)+di, and tel in FIG. 7, respectively.

'' The two-leg rush current exceeded the withstand capacity of the switching element Q1, and there was a risk that the switching element Q would overheat or be destroyed.

The above situation is likely to occur when the resistance value of the load L D is large. For example, a fluorescent lamp can be treated as a resistor with equal restrictions when lit at a high frequency, but at the end of its life, it becomes difficult to discharge, and therefore its resistance value becomes large, resulting in the above-mentioned rush current flowing.

As a means to solve the problem of destruction of the switching element Q1 due to rush current as in the inverter device shown in Fig. 6, as shown in Figs. A rush current limiting inductance element L3 consisting of a choke coil is inserted into the closed loop circuit to lower the peak value of the rush current so that the rush current flowing through the switching element Q1 is less than or equal to the surface of the switching element Q1. is possible.

The inverter device in FIG. 9 shows an example in which a rush current limiting inductance element L3 is inserted on the side of the capacitance element C1, and FIG. 10 shows an example in which a rush current limiting inductance element L3 is inserted on the side of the switching element Q1. ．． An example in which 3 is inserted is shown.

[Problem to be solved by the invention]

In the case of the inverter device shown in Fig. 9, the switching element Q
1 is switched from on to off, and when the current 1 r- flowing through the load current limiting inductance element L2 flows into the capacitance element CI, the rush current limiting inductance element L3 blocks the inflow. As a result, L3 is connected between both ends of the rush current limiting inductance element L3.
A voltage (d+/dt) is generated and applied to the switching element Q1, and noise is generated due to the surge voltage.

Further, in the case of the inverter device shown in FIG. 10, when the switching element Q is turned off, a current change in the rush current limiting inductance elements I and 3 causes L 3 to be formed between both ends of the rush current limiting inductance element L3. (
dt/dt) is generated, and the switching element Q1
A surge voltage is applied to the

As described above, when the rush current limiting inductance element L3 is inserted into the closed loop circuit consisting of the DC power supply E1, the capacitance element C1, and the switching element Q1, a surge voltage is applied to the switching element Q1.
Since there is a problem of noise generation and it is necessary to suppress the surge voltage to be lower than the withstand voltage of the switching element Q1, it is not possible to use an inductance element with a large inductance value as the rush current limiting inductance element L3. For this reason, it has not been possible to improve the ability to suppress rush current.

An object of the present invention is to provide an inverter device that can enhance the ability to suppress rush current and suppress the generation of surge voltage due to steady oscillating current.

[Means to solve the problem]

The in-hark device of the present invention connects a series circuit of a load and a load current limiting inductance element to a DC power source via a switching element that periodically turns on and off. G is applied to the series circuit so that power is intermittently supplied as the switching element turns on and off. Furthermore, a capacitance element is provided as a conduction path for the oscillating current of the series circuit of the load and the load current limiting inductance element when the switching element is off. This capacitance element forms a closed loop circuit with the switching element and the DC power supply. An inductance element for limiting current is inserted in series in the closed loop circuit to be electromagnetically coupled to the inductance element for limiting load current.

[For production]

In the configuration of the present invention, by inserting the rush current limiting inductance element into the closed loop circuit composed of the DC power supply, the capacitance element, and the switching element, the switching element When turned on, the rush current flowing through the closed loop circuit can be suppressed by the rush current limiting inductance element.

On the other hand, in response to the oscillating current flowing through the series circuit of the load and the load current limiting inductance element, the rush current limiting inductance element is electromagnetically coupled to the load current limiting inductance element. Even if the path of the oscillating current switches between the switching element and the capacitance element as the switching element turns on and off, the magnetic flux of the inductance element for inrush current limitation is common to the magnetic flux of the inductance element for load current limitation, and the rapid No significant magnetic flux change occurs, but the change occurs gradually in accordance with the change in the current flowing through the load and the load current limiting inductance element. Therefore, with respect to the oscillating current flowing through the load and the series circuit of the load current limiting inductance element, the rush current limiting inductance element does not act as a large current limiting element, and no large surge voltage is generated.

Therefore, it is possible to increase the inductance value of the rush current limiting inductance element to improve the ability to suppress rush current.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of an inverter device according to a first embodiment of the present invention.

The inductance device of FIG. 1 has an inductance having an electromagnetically coupled winding n and a winding n2 in place of the rush current limiting inductance element L3 and the load current limiting inductance element L2 of the capacitance element 01 example in FIG. This uses element L4. winding n1
corresponds to the runche current limiting inductance element L3 in FIG. 9, the winding n2 corresponds to the load current limiting inductance element I52, and both windings n1. The polarity of n2 is indicated by a mark.

The rest of the configuration is the same as the in-hark device shown in FIG.

In this in-hake device, the circuit operation is improved by inserting the winding n of the inductance element L4, which is an inductance element for limiting rush current, into the closed loop circuit composed of the DC type tAE1, the capacitance element C1, and the switching element Q1. When the switching element Q is turned on before the voltage applied to the switching element Q1 returns to zero, a rush current (shown in FIG. 8(b)) flows through the closed loop circuit. The peak value of can be suppressed by the inductance component of the winding n1.

On the other hand, with respect to the oscillating current ■1 flowing through the series circuit of the winding n2 of the load LD and the inductance element L4 which is the inductance element for limiting the load current, the winding n1 is
, and the winding n2 are electromagnetically coupled, so the oscillating current ■1
．． Even if the path of is switched between the switching element Q1 and the capacitance element C1 as the switching element Q1 turns on and off, the magnetic flux of the winding n1 is common to the magnetic flux of the winding n2. The oscillating current 11 degrees flowing through the load LD and the winding n2 changes gradually. For this reason, the load L
D, and the oscillating current 1 flowing through the series circuit of the turns vAn2
1. On the other hand, the winding rl ] does not become a large current limiting element, and no large surge voltage occurs.

Therefore, the generation of noise can be suppressed to a sufficiently low level, and the →noise voltage applied to the switching element Q1 can also be suppressed to a low level.

Therefore, by increasing the number of turns of the winding n, and increasing the inductance value of the winding n1, it is possible to sufficiently increase the ability to suppress the peak value of the rush current.

In addition, the winding n1, which is an inductance element for limiting rush current, and the winding n2, which is an inductance element for load current limitation, are electromagnetically coupled, and both can be integrated as an inductance element L4, so the inverter device as a whole can be made smaller. can be achieved.

Note that the circuit operation other than the above is the same as that in FIG. 9.

FIG. 2 is a circuit diagram showing the configuration of an inverter device according to a second embodiment of the invention.

The inverter device of FIG. 2 has windings n1. It uses an inductance element L5 in which the polarity of n2 is opposite to that in FIG. 1, and the other configuration is the same as that in FIG.

Figure 3 is a time chart of each part in Figure 2, and (a)
is the voltage ■ applied across the switching element Q1.

B, and fbl is the current I flowing through the switching element Q1. , (C1 indicates the current IL flowing through the series circuit of the load LD and the load current limiting inductance element L2, and (dl indicates the voltage 1.1 across the winding n1.

In the case of this embodiment, the voltage of fd+ in FIG.
1 acts in the direction of reducing the voltage applied to the switching element Q1, and it becomes possible to use a switching element Q1 with a lower withstand voltage than in the case of FIG. Other functions and effects are similar to those of the embodiment shown in FIG.

FIG. 4 is a circuit diagram showing the configuration of an inverter device according to a third embodiment of the present invention.

The inverter device of FIG. 4 has an inductance having an electromagnetically coupled winding n1 and winding In2 in place of the rush current limiting inductance element L3 and the load current limiting inductance element L2 on the switching element Q1 side shown in FIG. This uses element L4. winding n,
corresponds to the rush current limiting inductance element L3 in FIG. 10, and the winding n2 corresponds to the load current limiting inductance element I-2. Although polarity is not shown, it can be considered in the same manner as in the first and second embodiments.

The rest is the same as the inverter device shown in FIG.

In this embodiment as well, the winding n of the inductance element L4
, limits the rush current, and this winding n1
is electromagnetically coupled to the winding n2, and as in the first embodiment, the oscillating current (1) flows through the series circuit of the load LD and the winding n2. On the other hand, the winding n does not become a large current limiting element and does not generate a large surge voltage. Therefore, the same effects as in the first embodiment can be achieved.

FIG. 5 is a circuit diagram showing the configuration of a half-blinder type inverter device according to a fourth embodiment of the present invention.

In the inverter device shown in FIG. 5, a switching element Q2. Series circuit of Q3 and diode D2. The series circuit of D3 is connected in parallel, and the winding n1 of the inductance element T and 6 is connected to the diode D2. D3 connection point and switching element Q2. A series circuit of a capacitor C2, a load I-D2 such as a discharge lamp, and a winding n2 of an inductance element L6 is connected in parallel with the switching element Q2.
Both switching elements Q2. Q3 is connected to drive circuits DR, DR according to a control signal output from control circuit CR2.
2, they are turned on alternately. In this case, the winding n1 of the inductance element L6 acts as a rush current limiting inductance element, and the winding n2 acts as a load current limiting inductance element.

This half-bridge type inverter device consists of two switching elements Q2. By alternately turning on Q3, high frequency power is supplied to the load LD2.

This inverter device includes, for example, a load circuit (load L D
, , winding n2. The switching element Q2. When Q3 is alternately turned on, a leading phase current flows through the load circuit.

To explain specifically, the current first flows through the path of DC power supply E2 - capacitor C2 = ii LD2 - winding n2 -> switching element Q3 - DC type BE, and then through diode D3 - winding n1 - winding n2 - Flows through the path of load L D 2 - capacitor C2 - DC power supply E2 → diode D3,
Next, capacitor C2 → switching element Q2 → winding n
2 -> load LD2 -> capacitor C2, and then from capacitor C2 - load LD2 - winding n2 - winding vAn, -
The current flows through the path from diode D2 to capacitor C2.

In the above, the switching element Q2 is caused by the accumulated charge of the diode D3 acting as a capacitance element.
At the moment when the inductance element L6 becomes conductive, a rush current attempts to flow from the DC power supply E2 to the switching element Q2 through the diode D3, but the peak value of this rush current is suppressed by the winding n1 of the inductance element L6.

On the other hand, diode D2 or diode D3 and load LD
2 and winding n2, for an oscillating current through winding n
Since the winding n1 is electromagnetically coupled to the winding n2, the winding n1 does not become a large current limiting element as in the previous embodiment, and the generation of the 4-noge voltage can be suppressed. Therefore, the same effects as those of each of the embodiments described above are achieved.

In addition, in FIG. 5, even when a slow phase current flows through the load circuit, the inductance element L6 acts in the same manner as in the above embodiment.

〔Effect of the invention〕

According to the inverter device of the present invention, a rush current limiting inductance element inserted in a closed loop circuit composed of a DC power supply, a capacitance element, and a switching element is connected to a load current limiting inductance element connected in series with a load. Due to electromagnetic coupling, the magnetic flux of the inductance element for rush current limitation changes slowly regardless of changes in the current path due to switching on and off of the switching element, and the inductance element for rush current limitation is used to limit the load and load current. It does not become a large current limiting factor for the oscillating current passing through the inductance element. Therefore, the inductance value of the rush current limiting inductance element can be made sufficiently large, the rush current flowing through the switching element can be sufficiently suppressed, and the surge voltage generated in the rush current limiting inductance element can be suppressed. Can be done. In addition, the inductance element for limiting rush current and the inductance element for limiting load current are electromagnetically coupled.
Since both can be integrated, the inverter device as a whole can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a first embodiment of the present invention;
FIG. 2 is a circuit diagram showing the configuration of a second embodiment of the present invention;
3 is a waveform diagram of each part of FIG. 2, FIG. 4 is a circuit diagram showing the configuration of a third embodiment of the present invention, and FIG. 5 is a circuit diagram showing the configuration of a fourth embodiment of the present invention. , FIG. 6 is a circuit diagram showing the configuration of a conventional example of an inverter device, FIG. 7 is a waveform diagram of various parts of the conventional example during proper operation, and FIG. 8 is a waveform diagram of various parts of the conventional example during improper operation. FIG. 9 and FIG. 10 are circuit diagrams each showing the configuration of a proposed example. El...DC power supply, LD...Load, Ql...Switching element, Dl...Diode, C1...Capacitor, Ll...Inductance element, L4...
Inductance element, nl, n2...winding 1) f) U D

Claims (1)

[Claims] A series circuit of a DC power source, a switching element that periodically turns on and off, a load that is intermittently supplied with power from the DC power source as the switching element is turned on and off, and an inductance element for limiting load current, and a series circuit that includes a load current limiting inductance element, and a capacitance element that serves as a conduction path for the oscillating current of the series circuit of the load and the load current limiting inductance element and that forms a closed loop circuit with the switching element and the DC power supply, and a capacitance element that is inserted in series in the closed loop circuit. An inverter device further comprising a rush current limiting inductance element electromagnetically coupled to the load current limiting inductance element.