JPS5984412A - Transformer - Google Patents

Abstract

PURPOSE:To make a detected voltage ratio according to the existence of DC biased magnetization larger by a method wherein a discontinous part, where the leakage flux is produced, is provided in a closed magnetic circuit composing a transformer, and a biased magnetization detecting coil is provided surrounding the closed magnetic circuit and an auxiliary coil, provided so as to cross the flux passing through the closed magnetic circuit, is connected to the biased magnetization detecting coil in series while performing demagnetization. CONSTITUTION:An inverter type lighting circuit is composed of a transformer Ts, a control circuit In and an inverter protection circuit P. In this configuration, a closed magnetic circuit core 1 is composed of a center leg 101 (101A, 101B), left side and right side legs 102 and 103 and yokes 104 and 105 and two such cores are butted with a spacer 106 inbetween to form a discontinuous part and leakage flux is produced. At that time, a biased magnetization detecting coil 113 is provided surrounding the closed magnetic circuit and an auxiliary coil 114 crossing the flux is also provided and the coil 114 is connected to the coil 113 in series while performing demagnetization.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transformer suitable for use in an inverter type power supply device using semiconductor switching elements.

Normally, in a discharge lamp such as a fluorescent lamp, the noemissions from both electrodes rarely disappear at the same time at the end of its life, and often only the emission from one electrode disappears. Therefore, at the end of the life of the discharge lamp, a so-called half-wave discharge occurs, and a direct current flows through the output winding of the oscillation transformer of the power supply device, and the iron core of this transformer may be excited by the direct current.

To prevent this, it is necessary to detect the half-wave discharge state and limit the operation of the semiconductor element during the half-wave discharge. Conventional methods for detecting a half-wave discharge state include detecting an increase in the input current of the transformer, detecting changes in the discharge lamp tube voltage, and installing an auxiliary winding on the transformer to detect the discharge lamp tube voltage. Although methods for detecting voltage differences between positive and negative asymmetric waveforms are known, these methods have the disadvantage of requiring complicated detection circuits. Therefore, the inventor of the present application first provided a discontinuous part that causes leakage magnetic flux in the middle of the closed magnetic circuit of a closed magnetic circuit iron core in which multiple windings are fully wound, and installed a biased magnetism detection coil so as to surround the closed magnetic circuit from the outside. proposed a transformer equipped with
No. 36529). In this transformer, when a state of DC biased magnetization occurs, the output voltage of the detection coil increases, so by determining the increase in the output voltage of the detection coil, it is detected that a state of DC biased magnetization has occurred. be able to.

Therefore, if this transformer is used as an oscillation transformer,
When a DC biased magnetic state occurs, it can be easily detected and the operation of the semiconductor element of the discharge lamp lighting circuit can be restricted. [7] However, in the transformer proposed earlier, the ratio of the detected voltage obtained from the biased magnetism detection coil during abnormal conditions (when DC biased magnetization occurs) and normal times (when DC biased magnetization does not occur) is In some cases, it is not possible to obtain a sufficiently large value, and it is rarely necessary to use an expensive circuit with high discrimination ability as a circuit for discriminating the output voltage of the biased magnetism detection coil.

An object of the present invention is to make the ratio of the detection voltage when DC bias magnetization occurs and the detection voltage when DC bias magnetization does not occur larger than that previously proposed by the inventor. Our goal is to provide you with a transformed boiler.

In a transformer in which a plurality of windings are wound around a closed magnetic circuit core, the present invention provides a discontinuous portion that generates leakage magnetic flux in the middle of the closed magnetic circuit of the core, and detects biased magnetism so as to surround the closed magnetic circuit from the outside. A coil is provided, and an auxiliary coil provided to interlink with the magnetic flux passing through the closed magnetic path is connected in series with the biased magnetism detection coil in a depolarized manner.

If an auxiliary coil is provided as described above and connected in series with the biased magnetism detection coil in a depolarized manner, a part of the voltage induced in the biased magnetism detection coil when it is not biased will be transferred to the output voltage of the auxiliary coil. Therefore, the ratio between the detection voltage obtained from the bias detection coil when bias magnetization occurs and the detection voltage obtained from the bias magnet detection coil when bias magnetization does not occur is increased. I can do it.

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

FIG. 1 shows an example of the configuration of the transformer of the present invention when used as an oscillation transformer of a discharge lamp lighting device, together with a circuit of the lighting device, and in the same figure, TB is the transformer of the present invention, I
, P is a control circuit that constitutes an inverter together with the transformer Ts, and P is a protection circuit for the inverter, and these constitute an inverter-controlled lighting device. First, the structure of the transformer T8 of the present invention will be explained. In the figure, l consists of a central leg 101, left and right legs 102 and 103, and yoke parts 104 and 105 that connect both ends of these legs. It is a closed magnetic circuit iron core. This closed magnetic path iron core is made up of two E-shaped iron cores IA and 1B with their corresponding leg portions facing each other and the opposing portions of each leg abutted against each other with a non-magnetic spacer 106 interposed therebetween.E-shaped iron core IA.

The IB and the spacer 106 are combined and integrated by appropriate means. In this embodiment, discontinuous portions of the magnetic path are formed by the abutting portions of the core legs abutted together via the spacer 106, and leakage magnetic flux is generated from these discontinuous portions. One half 101 of the central leg of the iron core l divided into multiple parts by spacers 1 ( ) 6
A has a primary winding (110) and a feedback winding 111 tightly coupled to each other, and the other half 101B has a secondary winding 110 wound thereon.
2 is wrapped. Terminals a+b are drawn out from both ends of the primary winding 110, and an intermediate tap C is drawn out from the middle portion of the primary winding 110. Also, the feedback winding 111
Terminals d and e are drawn out from both ends of the secondary winding 112, and terminals f and g are drawn out from both ends of the secondary winding 112. Furthermore, the tag h and the amount are drawn out from the parts near both ends of the secondary winding 112, and the low voltage applied to the heater of the discharge lamp is applied between the terminal f and the tap h and between the terminal g and the tag l, respectively. The resulting zero iron core 1 is also wound with a biased magnetic detection coil 113 that surrounds the closed magnetic path of the iron core 1 from the outside, and an auxiliary coil 114 that interlinks with the magnetic flux passing through the closed magnetic path. There is. In the illustrated example, the detection coil 113 is arranged near the abutting portion of the iron core 1 (a discontinuous portion of the closed magnetic circuit), and the auxiliary coil 114 is wound around the abutting portion of the side leg portion 103 of the iron core 1. . The auxiliary coil 114 is connected in series with the detection coil 113 in a depolarized manner, and detection signal output terminals j and k are drawn out from both ends of the series circuit of the auxiliary coil 114 and the detection coil 113. And iron core 1 is winding 1
When a current having a direct current component flows through at least one of the magnets 10 to 112, the magnet is biased to direct current and magnetically saturated.

In the above transformer T8, it is assumed that the magnetic flux circulating through the iron core 1 is as shown in the arrow shown in the figure (the number of arrows represents the amount of magnetic flux), and the cross-sectional area of each side leg is the center leg. If the magnetic flux φ flows through the central leg 101f, the same amount of the magnetic flux φ is divided into both legs. In this case, magnetic resistance increases at discontinuous portions of the magnetic path, resulting in leakage magnetic flux. In other words, a leakage magnetic flux φr1 is generated at the discontinuous portion of the central leg 101, and a leakage magnetic flux φr2 in the opposite direction to the leakage magnetic flux φr1 is generated at the discontinuous portions of the side legs 102 and 103.

The magnetic flux passing inside the biased magnetism detection coil 113 is
Magnetic flux φ1 and leakage magnetic flux φr1 passing through the iron core of the central leg, magnetic flux φ2 passing through the iron cores of both left and right legs, and leakage magnetic flux φr
In the example of FIG. 1, the leakage magnetic fluxes φr2 and φ11 passing inside the detection coil 113 are in opposite directions, so they cancel each other out, and Since φ2 and φ weight are in opposite directions, a part of φ1 and φ2 cancel each other out. Therefore, the magnetic flux flowing inside the detection coil 113 is a part of the magnetic flux φ1 flowing through the central leg (in the example shown). magnetic flux for two arrows)
only remains. On the other hand, a portion of the leakage magnetic flux φr2 from both the left and right legs passes through the outside of the detection coil. That is, the detection coil 113 has a magnetic flux that is a vector composite sum of magnetic fluxes flowing inside the detection coil (that is, a magnetic flux that passes through the outside of the detection coil among the leakage flux generated from the discontinuous portions of the left and right legs). magnetic flux) are interlinked. This magnetic flux has a winding Ml 10
112, a voltage is induced in the bias detection coil 113. On the other hand, auxiliary coil 114
, pressure a is induced by a change in the magnetic flux φ2 flowing through the side leg portion 103. In the present invention, the auxiliary coil 114 is configured such that the magnitude of the voltage induced in the auxiliary coil 114 is approximately equal to the magnitude of the voltage induced in the biased magnetism detection coil 113 in a normal state where the iron core 1 is not subjected to DC bias magnetization. The number of turns is set. Therefore, under normal conditions, the voltage appearing across the series circuit of the auxiliary coil 114 and the biased magnetic detection coil 113 is a sufficiently small value close to zero.
In the above transformer, if the magnetic flux circulating through the iron core 1 becomes unbalanced in the direction of the arrow shown in the figure and in the counter-arrow direction, a state of so-called DC biased magnetization will occur. 1 is at or near magnetic saturation. In such a state, the magnetic resistance at the discontinuous part of the iron core 1 increases significantly, and it is difficult for the magnetic flux to pass through the core at the discontinuous part, and more magnetic flux passes through the outside of the core than when it is unsaturated. become. Therefore, in a state where DC bias magnetization occurs, the magnetic flux interlinking with the detection coil 113 increases, and the induced voltage of the detection coil 113 increases. On the other hand, in this state, the magnetic flux linking the auxiliary coil 114 decreases, and the voltage induced in the auxiliary coil 114 decreases, so the auxiliary coil 114
The voltage appearing across the series circuit of 14 and the biased magnetism detection coil 113 becomes much sharper than in normal conditions, and the waveform of this voltage becomes a highly distorted waveform. Therefore, it is possible to know that upward bias has occurred by detecting an increase in the voltage across the series circuit of the auxiliary coil 114 and the bias detection coil 113 or a distortion of its waveform.

Next, the circuit configuration of an inverter-controlled discharge lamp lighting device using the above transformer as an oscillation transformer will be explained. In Fig. 1, 2 is a commercial AC power supply, and 3 is a full-wave rectifier that rectifies the output of the AC' power supply. . The positive output terminal of the rectifier 3 is connected to the intermediate tag C of the primary winding 110 of the transformer via the constant current reactor 4, and the negative output terminal of the rectifier 3 is connected to the emitters of transistors 5 and 6 as semiconductor switching elements. Connected to a common connection point. The collectors of the transistors 5 and 6 are connected to one end a and the other end of a primary winding 110, respectively, and a capacitor 7 is connected in parallel between both ends a and b of the primary winding 110. Each pace of transistors 5 and 6 is connected to terminals e and d of feedback winding 114 of the transformer, and to one end of resistors 81 and 82, the other end of which is connected to resistor 9. Reactor 4 and 1 through
It is connected to the connection point with the intermediate tag C of the next winding 110. The control circuit IN of the inverter that oscillates at a high frequency is constructed by each of the above parts.Then, one heater 10a of the discharge lamp 10 is connected between the terminal f and the tap h of the transformer secondary winding 112, and the terminal The other heater 1obf: is connected between g and tap 1, and a discharge lamp is loaded to the secondary winding. To protect transistor 5.6, resistor 81. of resistor 9 is connected. The anode of the thyristor 11 is connected to one end on the '82 side, and the dart of the thyristor 11 is connected to the detection signal output terminal j. A resistor 12 is connected in parallel between the Gnit cathodes of the thyristor 11, and a Zener diode 130 cathode is connected to the connection point between the resistor 12 and the cathode of the thyristor 11.

The anode of the Zener diode 13 is connected to the anode of a diode 14 whose cathode is connected to the detection signal output terminal kK, and a capacitor 15 is connected between the anode of the diode 14 and the detection signal output terminal. The components of the thyristor 11 to the capacitor 15 constitute a non-performing protection circuit P.

When the power is turned on in the discharge lamp device described above, the transistors 5 and 6 are alternately conductive, the inverter oscillates, a high frequency voltage is applied to the discharge lamp 10, and the discharge lamp is lit.

When the discharge lamp 10 generates a half-wave discharge, a direct current flows through the secondary winding 112 of the transformer, the iron core 1 is excited by the direct current, and the impedance of the primary winding 110 decreases. In FIG. 1, a protection circuit P consisting of a thyristor 11 to a capacitor 15
If not, an excessive current would flow through the transistors 5 and 6 due to the decrease in the impedance of the primary winding, and there is a risk that these transistors would be damaged. On the other hand,
If a protection circuit PL as shown in Fig. 1 is provided, the discharge lamp lO
When a half-wave discharge occurs and the iron core becomes DC biased, a large detection voltage is induced in the biased magnetism detection coil 113, and this voltage exceeds the Zener level of the Zener diode 13 and provides an ignition signal to the thyristor 11. . Therefore, the thyristor 11 becomes conductive, lowering the pace potential of the transistors 5 and 6 to approximately the emitter potential. Therefore, these transistors are not cut off and their damage is prevented.

Next, the results of experiments conducted on the circuit shown in FIG. 1 will be described. In the experiment, as shown in the figure, the biased magnetic detection coil 113t was wound four turns near the butt part of the iron core, and the auxiliary coil 114 was wound one turn around the point β in the figure.
A 40W fluorescent lamp was used as zero. As a result, the waveform observed by the oscilloscope of the detected voltage ejk when the discharge lamp 10 is normal is as shown in Fig.
The peak-to-peak voltage value of the waveform modulated at a frequency of 60 Hz was approximately 0.6 V. Furthermore, the waveform of the detected voltage ejk when the discharge lamp IO was removed (no load) was almost the same as the waveform in Figure 2 (,) ad), and the peak-to-peak voltage value was also the same as in the case of the same figure. . On the other hand, when the discharge lamp 10 causes a half-wave discharge, the waveform of the detected voltage ejk becomes as shown in FIG. 2(b), and the peak-to-peak voltage is approximately 4.5
In other words, the detection voltage ejk during abnormality is the detection voltage ejk during normality.
h'), which is about 7.5 times k), and the voltage difference was about 3.9V◎ Also, slide the auxiliary winding 114 appropriately between point α and point β in Fig. 1 and adjust its position. It has become clear that when the voltage is changed, the induced voltage of the auxiliary winding 114 changes, and thereby the peak-to-peak voltage value of the detection voltage ejk changes in the range of 0.6v to 0.8v. In this case, the peak-to-peak voltage value of the detected voltage ejk during abnormality remained approximately 4.5V.

As described above, when the transformer of the present invention is used, the peak-to-peak voltage value of the detected voltage ejk during normal operation is set to 1. It can be made lower than Ov. Therefore, if the diode 14 is appropriately selected in accordance with the circuit shown in FIG.
Since the current flowing through 4 can be made constant, the Zener diode 13t can be omitted.For reference, as shown in FIG. 4, the auxiliary coil 114
Normality when an inverter-controlled discharge lamp lighting device similar to that shown in Fig. 1 is configured using a transformer Ts't'' with detection terminals j and k directly drawn out from both ends of the biased magnetic detection coil 113 without providing t-. The waveforms of the detection voltage ejk at the time of abnormality and the detection voltage e j k at the time of abnormality are shown in Fig. 5 (,) and (b), respectively.
). In this case, the same 40W low-light lamp was used as the load. In this case, the detected voltage during abnormal conditions is approximately 2.5 times the detected voltage during normal conditions, and unlike the transformer of the present invention, it was not possible to increase the voltage ratio between abnormal conditions and normal conditions.

In the above embodiment, the auxiliary coil 114 is wound with one turn around the side legs, but the number of turns of the auxiliary coil 1140 can be changed as appropriate depending on the number of turns of the bias detection coil 113. In addition, the auxiliary coil 114 can be wound so as to interlink with the magnetic flux flowing in the magnetic path of the closed magnetic path iron, and this auxiliary coil can also be wound around the central leg. In the example shown in Figure 1, the output of the rectifier 3 is smoothed. However, the present invention can be applied to the case where the power of this rectifier is smoothed and used, and the transformer of the present invention can be similarly applied to an inverter circuit using a battery as a power source. It goes without saying that the transformer of the present invention can also be applied to inverter circuits similar to the above example that use semiconductor switching elements other than transistors, and can also be applied to single-emption oscillation type oscillation transformers and separately excited inverters. It can also be used for the output of equipment. In short, the present invention can be applied to any transformer that produces leakage magnetic flux. In addition, the load is not limited to discharge lamps, but also cases where there is a risk of DC bias due to damage or missing rectifiers connected to the secondary side of the transformer, or cases where there is a risk of DC bias caused by a pair of semiconductor switching elements or active devices. It can be widely applied to cases where there is a risk of DC bias magnetization occurring due to unbalanced operation of elements.

In the example shown in FIG. 1, a feedback winding 111 is provided for use as an oscillation transformer of an inverter, but when the present invention is applied to a transformer that does not require a feedback winding, Of course, is omitted.

In the above embodiment, an outer iron core was used, but the present invention can be similarly applied to a case where an inner iron core 1' is used as shown in FIG. In this case, for example, the legs of the U-shaped iron cores IA' and IB' are brought into contact with each other, and a non-magnetic wave sensor 106' is interposed between the butting parts of one of the legs.
The other leg portions of A' and IB' are brought into direct contact with each other, and the discontinuous portions provided in both leg portions LA' and IB' of the iron core 1' are made into an uncontinuous lance. Then, the primary winding 110 and the feedback winding 111 are tightly coupled and wound around the iron core IA', and the secondary winding 112 is wound around the iron core IB'. In addition, a biased magnetic detection coil 1 is placed so as to surround the closed magnetic path of the iron core 1' from the outside.
13, and the auxiliary coil 114 is wound around the leg IB/. With this configuration, the discontinuous portion of the leg 101' and the leg 1
Since the cage of leakage magnetic flux can be made different depending on the discontinuous portion of 02', a detection voltage can be induced in the detection coil 113 without reducing the vector composite sum of the magnetic flux passing inside the detection coil 106' to zero. , and the same effect as the transformer shown in FIG. 1 can be obtained.

In the example shown in Figure 1, the detection coil is provided so as to surround from the outside all the closed magnetic circuits made up of the central leg and both left and right legs, but only some of the closed magnetic circuits are surrounded from the outside. For example, the detection coil 113 may be wound between the center leg 101 and one of the side legs 103 so as to surround the closed magnetic circuit formed by the center leg 101 and one of the side legs 102 from the outside. can.

As described above, according to the present invention, a biased magnetism detection coil is provided that surrounds the closed magnetic path from the outside, and an auxiliary coil that is provided to interlink with the magnetic flux passing through the closed magnetic circuit is used to reduce the biased magnetism detection coil. Since the polarity is set and the direct connection is made, the detection voltage during normal operation can be lowered, and the detection voltage when DC biased magnetization occurs can be reduced.
The ratio to the normal detection voltage can be increased. Therefore, the DC side 1 can be increased without using a complicated detection circuit.
It is possible to detect that j3&crab has occurred.

[Brief explanation of the drawing]

Figure 1 is a connection diagram showing an example of the configuration of the transformer of the present invention used in an inverter-controlled discharge lamp lighting device together with a circuit example of the lighting device. FIG. 3 is a schematic configuration diagram showing a modification of the present invention; FIG. 4 is a schematic configuration diagram showing an example configuration of a transformer previously proposed by the inventor of the present application; 5(a) and 5(b) are waveform diagrams showing detected voltage waveforms obtained when the transformer shown in FIG. 4 is used in a lighting device similar to that shown in FIG. 1.01, 1'... iron core , 101.101
', 102, 102'. 103... Legs of iron core, 106, 106'... Spacer, 110... Primary winding, 111... Feedback winding, 112... Secondary winding, 113... Biased magnetism Detection coil, 114... Auxiliary coil.

Claims (2)

[Claims] (1) In a transformer in which a plurality of windings are wound around a closed magnetic circuit core, a discontinuous portion that generates leakage magnetic flux is provided in the middle of the closed magnetic circuit of the core, and a biased magnetic field surrounds the closed magnetic circuit from the outside. A transformer characterized in that a detection coil is provided, an auxiliary coil is provided so as to interlink with the magnetic flux passing through the closed magnetic path, and the auxiliary coil is connected in series with the biased magnetism detection coil in a depolarized manner. vessel. (2) The closed magnetic circuit iron core is magnetically saturated due to DC polarization when a current having a DC component flows through at least one of the plurality of windings. transformer.