CN1941228B - converter transformer - Google Patents

Abstract

A converter transformer comprises a plurality of winding frames and a plurality of core groups. The winding frames respectively have a hollow portion and a first, a second and a third winding portion for winding a coil. The first winding portion is wound with a primary coil, and the second and third winding portions are wound with a secondary coil. One of the secondary coils of all the winding frames is connected in series in sequence, and the magnetic flux directions of the secondary coils of each winding frame are mutually repelling. The core groups respectively have a first core portion arranged in the hollow portion, and a second core portion connected to the first core portion to form a magnetic circuit.

Description

converter transformer

technical field

The invention relates to a converter transformer, in particular to a converter transformer applied to a converter module, which needs to obtain a voltage phase 180-degree output or multiple sets of output converters.

Background technique

Generally, the LCD panel uses a discharge lamp (Discharge Lamp) such as a cold cathode fluorescent lamp (CCFL) as the panel's backlight (Back Light), and this type of discharge lamp is driven by an inverter (Inverter) circuit. And in order to meet the requirement of high-voltage output, it is usually driven by a converter transformer.

Referring to Figures 1 and 2, it is a conventional converter transformer, which includes a bobbin frame 91, a first iron core 92 and a second iron core 93. A plurality of separation grooves 911 protrude from the side edge of the bobbin frame 91 , and respectively form a primary side winding area 912 and a secondary side winding area 913 . The primary side winding 912 and the secondary side winding 913 are respectively provided to connect the power supply and the load. However, as the size of the LCD panel increases day by day, the length and number of the lamp tubes used also increase relatively, so that the driving voltage also increases with the increase in the size of the LCD panel. Therefore, in general applications, the voltage division principle of the interval winding area III in the middle of the separation groove 911 is used to set the number of separation grooves 911 according to the voltage used, so that the reliability of the product can be improved.

Therefore, according to the ideal load usage status, it is a characteristic load with negative temperature equivalent impedance through the cold cathode tube (CCFL). In addition, the temperature rises and the impedance decreases after the cold cathode tube is turned on. Based on cost considerations, generally It adopts the method of connecting two cold-cathode tubes (CCFL) in parallel with one secondary side winding. However, since the impedance of the two cold-cathode tubes (CCFL) will not be exactly the same, it is easy to use cold-cathode tubes The tube end of the (CCFL) causes a shunt effect, resulting in uneven current between the two cold-cathode tubes (CCFL), resulting in a loss of excessive brightness difference.

However, the lamp tubes used today also use L-shaped and U-shaped lamps according to the needs. Therefore, the aforementioned lack of uneven brightness, if used to drive L-shaped and U-shaped lamps, the difference in brightness will be obvious , especially the phenomenon of electrode aging, it is necessary to find a solution.

In addition, in order to overcome the lack of non-uniform brightness of cold cathode tubes (CCFL), although some companies use the addition of a matching balance coil, the cold cathode tubes (CCFL) can achieve current mutual induction to obtain a better balanced current. In this way, although it can be moderately improved The absence of uneven brightness, however, the addition of matching balance coils not only relatively increases the cost, but also limits the space utilization of the circuit board.

Contents of the invention

The object of the present invention is to provide a converter transformer which can make the load current stable and tend to be consistent.

Another object of the present invention is to provide an open loop or closed loop series and parallel connection method to detect the feedback potential from the impedance voltage, and cooperate with the servo circuit to control the current to achieve the balance of the load current. flow transformer.

Therefore, the converter transformer of the present invention is provided to connect multiple loads, and the converter transformer includes a core group and a winding frame.

Each bobbin has a hollow part respectively, and a first winding part, a second winding part and a third winding part for a coil to be wound on, and a primary winding part is wound on the first winding part. side coils, the second and third winding parts are wound with secondary side coils, one of the secondary measuring coils of all bobbins is connected in series in sequence, and the magnetic flux of the secondary side coils of each bobbin Directions are mutually exclusive.

Each iron core group has a first iron core part arranged in the hollow part and a second iron core part connected with the first iron core part to form a magnetic circuit, and the second iron core part is arranged around the winding frame.

The effect of the present invention is that the primary side coil and the secondary side coil between the first, second and third winding parts are mutually coupled, and the change of the load current is used to make the adjacent secondary side coils on each winding group The magnetic flux changes of the coils are mutually exclusive according to their phases, which can not only stabilize the output of the induced voltage at both ends of the transformer, but also immediately improve and eliminate the phenomenon of uneven brightness at both ends of the cold cathode tube (CCFL), and increase the brightness of the cold cathode tube. (CCFL) Stability and reliability of luminous efficiency.

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a plan view, illustrates a kind of existing converter transformer;

Fig. 2 is a side view of Fig. 1;

Figure 3 is a circuit diagram illustrating a first preferred embodiment of the present invention;

Fig. 4 is an equivalent circuit diagram of Fig. 3;

Fig. 5 is a circuit diagram;

Fig. 6 is a circuit diagram;

Fig. 7 is an equivalent circuit diagram;

Fig. 8 is an equivalent circuit diagram;

Fig. 9 is an equivalent circuit diagram;

Fig. 10 is an equivalent circuit diagram;

Fig. 11 is a circuit diagram;

Figure 12 is a circuit diagram illustrating a second preferred embodiment of the present invention; and

Fig. 13 is a circuit diagram illustrating that the primary side coil and the secondary side coil are overlapped and wound.

Detailed ways

Referring to FIGS. 3 and 4 , the first preferred embodiment of the present invention includes two bobbins 8 and two core groups 9 . Each bobbin 8 is respectively connected to a load 120, and the bobbins 8 respectively have a hollow portion (not shown), and a first winding portion 81 and a second winding portion 82 for coil winding. And a third winding part 83 , the first winding part 81 is wound with the primary side coil 34 , and the second and third winding parts 82 and 83 are respectively wound with the secondary side coils 35 and 36 .

The above-mentioned iron core group 9 respectively has a long bar-shaped first iron core part 901 and an inverted U-shaped second iron core part 902, and is placed around the above-mentioned bobbin 8, and the above-mentioned iron core group 9 is formed after electrification The magnetic circuit forms an electromagnetic effect with the primary side coil 34 and the secondary side coils 35 and 36 .

When the power supply (Vi) supplies power, the two windings of the converter transformers P1 and P2 are input at the same time. Since the other ends of the P1 and P2 windings are grounded, an excitation effect is generated, and the magnetic flux changes through each winding W1, P2 in each closed magnetic circuit. W2 is induced by the windings W1 and W2 to change its magnetic flux, thereby generating an induced potential and outputting it to the cold cathode tube (that is, the load 120 , the discharge lamp), forming a load circuit. When the secondary side load current i2, i2' flows, the primary side excitation current also increases to i1 and i1', and maintains the necessary magnetic field effect in the electromagnetic conversion. However, based on the coupling effect, winding impedance and distributed capacitance of each converter transformer are different, the output voltage is also different, and the load characteristics of the discharge lamp are also different with the load curve after the lamp is lit, so In this first embodiment, each additional set of S1 and S2 lead wires is used to mutually repel the magnetic flux direction of the W1 induced potential and the magnetic flux direction of the S1 induced potential, and the magnetic flux direction of the W2 induced potential is consistent with that of the S1 induced potential. The magnetic flux direction of the induced potential of S2 is just mutually repulsive, so when S1 and S2 in the two windings P1 and P2 generate induced potential, the current directions i3 and i3' are properly connected in series, so that the two converter transformers are mutually induced The respective magnetic fluxes change to achieve the function of load current balance (equivalent to the function of discharge lamp current balance).

Referring to Fig. 5, in the converter transformer of the present invention, the bobbins 8 and the core groups 9 are respectively set into four groups, and are respectively connected to four loads 120, as for the coils 34, 35, The winding method of 36 and the bobbin 8 is the same as that in FIG. 4 , and the driving mode and expected effect are also the same, so no further description will be given.

Referring to Fig. 6, the converter transformer of the present invention is the same as Fig. 5, and both include four sets of winding frames 8 and four sets of core groups 9, and are respectively connected to four loads 120. In different places, not only are the winding frames The secondary side coil 36 of 8 is connected in series in a closed loop manner, and one end 361 of the secondary side coil 36 is grounded, and the other end 362 is connected to an impedance 130 and then grounded. The other end 362 is used as the current detection end, and the driving circuit (not shown) is used to adjust the voltage of the circuit, so as to achieve the function of adjusting the brightness of the discharge lamp (ie, the load 120). As for, in FIG. 6 Although only one impedance 130 is provided, two or more impedances can be provided depending on the requirement. In addition, the effects expected to be achieved in FIG. 6 are the same as those described above, and no further description is given here.

Referring to Fig. 7, the converter transformer of the present invention is an equivalent circuit diagram, comprising two bobbins 801, 802 and two core groups (referring to Fig. 3), and connected to a first load 121 and a second load 122 respectively . The secondary side coil 36 on the third winding portion 83 of the first winding frame 801 and the secondary side coil 35 on the second winding portion 82 of the second winding frame 802 are connected in series in a closed loop manner, That is, the secondary side coil 36 on the first and second winding frames 801, 802 has one end 361 connected to the first and second loads 121, 122, and the first and second winding frames 801, 802 have The secondary side coil 35 of each has a grounded end 351, and the other end 362 of the secondary side coil 36 on the first bobbin 801 is connected to the other end 352 of the secondary side coil 35 on the second bobbin 802 The other end 352 of the secondary side coil 35 of the first winding frame 801 is connected to the other end 362 of the secondary side coil 36 on the second winding frame 802, and the other ends of the first and second loads 121, 122 One end is connected to an impedance 130 and then grounded, and the other end of the first and second loads 121, 122 and the impedance 130 form a current detection end I. In FIG. 7, after the feedback potential is taken out from the current detection terminal I, a servo circuit 140 is used to adjust the voltage, and a drive circuit 150 is provided to provide the energy required by the first and second bobbins 801 and 802. , by means of the current detection mechanism, the purpose of maintaining a stable input voltage and making the brightness of the loads 121 and 122 balanced and consistent can be achieved.

Referring to FIG. 8, the control mechanism of the converter transformer of the present invention is the same as that in FIG. The side coils 35 are connected in series in a closed loop mode. The difference is that the bobbins, core groups (not shown) and loads are all set into four groups. As for the connection structure of the circuit, that is, the above-mentioned first, second, The secondary side coil 36 on the third winding portion 83 of the third and fourth bobbins 801, 802, 803, 804 has one end 361 connected to the first, second, third, and fourth loads 121, 122, 123, 124 and The other end 362 of one end 351 of the secondary side coil 35 connected to the second winding part 82, and the second winding frame 82 of the above-mentioned first, second, third, and fourth winding frames 801, 802, 803, 804 The other end 352 of the secondary side coil 35 on the circuit is grounded, and the other ends of the first, second, third, and fourth loads 121, 122, 123, and 124 are connected to an impedance 130 and then grounded, and the first, second The other end of the loads 121, 122, 123, 124 and the impedance 130 form a current detection terminal I. The current detection mechanism is obtained by using the current detection terminal I to achieve the purpose of maintaining a stable input voltage and making the brightness of each load balanced and consistent.

Referring to Fig. 9, the converter transformer of the present invention is an equivalent circuit diagram, comprising two bobbins 801, 802 and two core groups (referring to Fig. 3), and connected to a first load 121 and a second load 122 respectively . After the secondary side coil 36 on the third winding part 83 of the above-mentioned first and second bobbins 801, 802 is connected in series with the loads 121 and 122 respectively, and then connected to the secondary side coil 35 on the second winding part 82 It is connected in series in a closed loop manner, that is, the secondary side coil 35 on the second winding part 82 of the above-mentioned first and second bobbins 801, 802 has one end 351 connected to the first and second loads 121, 122 and The other end 352 of the ground, the secondary side coil 36 on the third winding part 83 of the above-mentioned bobbin 801 all have an end 361 connected to the other end of the first and second loads 121, 122 and connected to an impedance 130. The other end 362 is grounded, and the other end 362 of the secondary side coil 36 of the third winding portion 83 and the impedance 130 form a current detection terminal II. The current detection mechanism is obtained by using the current detection terminal II, and then a servo circuit 140 is used for voltage adjustment, and the energy required by the first and second bobbins 801 and 802 is provided through a drive circuit 150, so that the current detection mechanism to achieve the purpose of maintaining a stable input voltage so that the brightness of each load is balanced and tends to be consistent.

Referring to Fig. 10, the control mechanism of the converter transformer of the present invention is the same as that of Fig. 9, and both use the secondary side coil 36 on the third winding portion 83 of the bobbin to be connected in series with the loads 121, 122, 123, 124 Afterwards, it is connected in series with the secondary side coil 35 on the second winding part 82 in a closed-loop manner. The difference is that the bobbin frame, the core group (not shown), and the load are all set into four groups. As for The connection structure of the line, that is, the secondary side coil 35 on the second winding portion 82 of the first, second, third, and fourth bobbins 801, 802, 803, and 804 has a wire connected to the first, second, and fourth bobbins. One end 351 of three or four loads 121, 122, 123, 124 and the other end 352 are all grounded, and one end 361 of the secondary side coil 36 on the third bobbin frame 83 of the first bobbin frame 801 is connected to the second bobbin frame 801. The other end of four loads 124, one end 361 of the secondary side coil 36 on the third winding frame 83 of the second winding frame 802 is connected to the other end of the first load 121, the third winding of the third winding frame 803 One end 361 of the secondary side coil 36 on the bobbin 83 is connected to the other end of the second load 122, and one end 361 of the secondary side coil 36 on the third bobbin 83 of the fourth bobbin 804 is connected to the third The other end of the load 123, the other end 362 of the secondary side coil 36 on the third winding frame 83 of the first, second, third, and fourth winding frames 801, 802, 803, and 804 is connected to an impedance 130 and then grounded. A current detection terminal II is formed between the other end 362 of the secondary side coil 36 on the third bobbin 83 and the impedance 130 . The current detection mechanism is obtained by using the current detection terminal II, and then a servo circuit 140 is used for voltage adjustment, and a drive circuit 150 is provided to provide the first, second, third, and fourth bobbins 801, 802, 803, and 804 required The energy of the current detection mechanism is used to maintain a stable input voltage, so that the brightness of each load is balanced and tends to be consistent.

Referring to Fig. 11, the converter transformer of the present invention is provided with two bobbins 8 and two core groups 9 similarly to Fig. 3, and the overall structure is the same as Fig. The secondary side coil 36 on the third winding portion 83 of the bobbin 8 is connected in series in a closed loop manner, and both ends 361 and 362 of the secondary side coil 36 are grounded. As for the driving mode and the expected effect, it is the same, and no further explanation will be given.

According to the above, in Fig. 3 to Fig. 11 of the present invention, they are all affected by the load current, so that the magnetic flux changes of the secondary side coils 35, 36 of the second and third bobbins 82, 83 are in a phase-dependent manner. Mutual exclusion phenomenon to achieve the purpose of load current balance. In Figures 6 to 10, the impedance 130 is also used to obtain the feedback potential, and the servo circuit 140 and the drive circuit 150 are used to detect the effect of the current mechanism on the load to balance the current. The purpose of making the current of discharge lamps uniform and consistent.

To sum up the above, the present invention is shown in Fig. 3 to Fig. 11, which can not only stabilize the output of the induced voltage of the converter transformer, but also eliminate the phenomenon of uneven brightness at both ends of the cold cathode tube (CCFL), and improve the stability of the luminous efficiency of the lamp tube. performance and reliability, and after overcoming the problem of uneven brightness, it can further meet the increasing trend of LCD panel size, so the above-mentioned effects and advantages are indeed achieved.

Referring to FIG. 12 , the second preferred embodiment of the present invention includes two bobbins 8 and two core groups 9 .

Each bobbin 8 has a hollow part, and the first, second, third and fourth winding parts 81, 82, 83, 84 for a coil to be wound. The first and fourth winding parts 81, 84 The primary side coil 34 is wound thereon, and the secondary side coils 35 , 36 are wound around the second and third winding portions 82 , 83 .

Each core group 9 has a first core part 901 and a second core part 902 respectively, and is arranged around the above-mentioned bobbin 8, and the magnetic circuit formed by the above-mentioned core part after electrification is connected with the above-mentioned primary side coil 34 and The secondary side coils 35,36 form an electromagnetic effect, and the first, second, third, and fourth winding parts 81,82,83,84 of the above-mentioned bobbin 8 have the primary and secondary side coils 34,35, The change of the magnetic flux of 36 is affected by the load current and is mutually exclusive according to its phase.

The driving situation of the third embodiment is the same as that of the second embodiment of FIG. 3 , the difference is that on the bobbin 8 with two primary side coils 34, one of the secondary side coils 36 is connected in series. The closed circuit achieves the same magnetic flux change as in the second embodiment, which is mutually exclusive according to the phase, and then acts to balance the current of the load, so that the current of the discharge lamp is uniform and tends to the same purpose.

Referring to Fig. 13, the converter transformer of the present invention includes two bobbins 8 and two core groups 9, the general structure of which is the same as that of Fig. 3, except that one of the primary side coils 34 on the above bobbin 8 A secondary side coil 37 is wound on top of it in a superimposed manner, thereby achieving the same effects and advantages as above, and no further description is given here.

Claims (9)

1. A converter transformer, providing multiple loads connected, the converter transformer comprising a plurality of bobbins, and a plurality of core groups, characterized in that: The above-mentioned bobbins respectively have a hollow part, and a first winding part, a second winding part and a third winding part for a coil to be wound on, and a primary winding part is wound on the first winding part. side coils, the second and third winding parts are wound with secondary side coils, one of the secondary side coils of all bobbins is connected in series in sequence, and the magnetic field of the secondary side coils of each bobbin frame and the above-mentioned iron core group respectively has a first iron core part arranged in the hollow part, and a second iron core part connected with the first iron core part to form a magnetic circuit, and the second iron core part is placed on around the above bobbin. 2. The converter transformer according to claim 1, characterized in that: In the winding frame, at least one set of primary side coils and secondary side coils are overlapped and wound. 3. The converter transformer according to claim 1, characterized in that: One of the secondary side coils of all bobbins is sequentially connected in series to form a closed loop. 4. The converter transformer according to claim 1, characterized in that: One of the secondary side coils of all bobbins is sequentially connected in series to form a closed loop, and one end of the secondary side coil forming the closed loop series connection is grounded, and the other end is connected to an impedance and then grounded. 5. The converter transformer according to claim 1, characterized in that: One of the secondary side coils of all bobbins is sequentially connected in series to form a closed loop, and both ends of the secondary side coil forming the closed loop series connection are grounded. 6. The converter transformer according to claim 1, characterized in that: Each bobbin is respectively connected to a load, and the secondary side coil of the third winding part on one bobbin is sequentially connected with the secondary side coils of the second winding part on the other bobbin in a closed loop mode. series connection, that is, one of the secondary side coils on all bobbins has one end connected to each load, the other secondary side coil on all bobbins has one end connected to ground, and one of the above two The other end of the secondary side coil is sequentially connected to the other end of another secondary side coil on the adjacent bobbin, and the other end of the load is connected to an impedance and then grounded, and the other end of the load is connected to The middle of the impedance constitutes a current detection terminal. 7. The converter transformer according to claim 1, characterized in that: One end of the secondary side coil on the third winding part of all bobbins is connected to a load, and the other end of the load is sequentially connected to the two coils on the second winding part of the bobbin adjacent to itself. The secondary coils are connected in series in a closed loop, that is, one of the secondary coils on all bobbins has one end connected to each load and the other end to ground, and the other secondary coil on all bobbins Each has one end connected to the other end of the load adjacent to itself and the other end connected to an impedance and then grounded, and the other end of the secondary side coil connected to the impedance and the middle of the impedance form a current detection end. 8. A converter transformer for connecting multiple loads, the converter transformer includes multiple bobbins and multiple core groups, characterized in that: The above-mentioned winding frame has a hollow part and at least four winding parts for winding a coil, wherein at least two winding parts are wound with primary side coils, and the remaining winding parts are wound with secondary coils. side coils, each bobbin has at least two secondary side coils whose magnetic flux directions are mutually exclusive; and The above-mentioned iron core groups respectively have a first iron core part arranged in the hollow part, and a second iron core part connected with the first iron core part to form a magnetic circuit, and the second iron core part is arranged around the above-mentioned winding frame. 9. The converter transformer according to claim 8, characterized in that: One of the secondary side coils of all bobbins is sequentially connected in series to form a closed loop. the

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