JP7251429B2 - power supply - Google Patents

Description

Embodiments of the present invention relate to power supplies.

FETs (Field Effect Transistors) are used as switching elements or rectifying elements in boost chopper circuits and step-down chopper circuits. FETs include those made of Si (silicon) and those made of SiC (silicon carbide) and GaN (gallium nitride), which are called next-generation materials. FETs using SiC or GaN have high-speed switching performance as one of their characteristics. Therefore, in a chopper circuit using FETs made of SiC or GaN, the operating frequency of chopper control can be increased.

Higher frequencies can reduce the size of peripheral components and the size of power supplies. On the other hand, switching loss of switching elements or rectifying elements is one of the problems in increasing the frequency.

A soft switching technique called TCM (Triangular Current Mode) control is known as one technique for suppressing switching loss. However, when TCM control is performed, there is a concern that an expensive microcomputer capable of digital control must be used, resulting in complication of the circuit and increase in price. For this reason, power supply devices are desired to be able to suppress switching loss with a simple configuration.

JP 2019-121517 A

An object of the present invention is to provide a power supply device capable of suppressing switching loss with a simple configuration.

According to an embodiment of the present invention, a high-potential input terminal and a low-potential input terminal connected to a DC power supply, a high-potential output terminal and a low-potential output terminal connected to a DC load, the high-potential input terminal and the A first switching element provided between a low potential input terminal, a second switching element provided between the first switching element and the low potential input terminal, the first switching element and the second switching element an inductor having one end connected to a connection point of a switching element and the other end connected to the high potential output terminal; the other end of the inductor and one end connected to the high potential output terminal; a smoothing capacitor having the other end connected to a low potential output terminal; and a first drive circuit for controlling switching of the first switching element based on the voltage of the inductor and the current flowing through the first switching element. and a second drive circuit that controls switching of the second switching element based on the voltage of the inductor and the current flowing through the second switching element, wherein the first drive circuit and the second drive circuit are: After the first switching element is turned on and the second switching element is turned off, the first switching element is turned off, the second switching element is turned on, and the first switching element is turned on again. A power supply device is provided in which each of the first switching element and the second switching element is turned off before being turned into a state.

According to the embodiments of the present invention, it is possible to provide a power supply device capable of suppressing switching loss with a simple configuration.

1 is a block diagram schematically showing a power supply device according to an embodiment; FIG. 2(a) to 2(g) are explanatory diagrams schematically showing an example of the operation of the power supply device according to the embodiment. 3A to 3E are graph diagrams schematically showing an example of the operation of the power supply device according to the embodiment.

Each embodiment will be described below with reference to the drawings.
Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each portion, the size ratio between portions, and the like are not necessarily the same as the actual ones. Also, even when the same parts are shown, the dimensions and ratios may be different depending on the drawing.
In addition, in the present specification and each figure, the same reference numerals are given to the same elements as those described above with respect to the already-appearing figures, and detailed description thereof will be omitted as appropriate.

FIG. 1 is a block diagram schematically showing a power supply device according to an embodiment.
As shown in FIG. 1, the power supply device 10 includes a high potential input terminal 11, a low potential input terminal 12, a high potential output terminal 13, a low potential output terminal 14, a first switching element 21, a second A switching element 22 , an inductor 24 , a smoothing capacitor 26 , a first drive circuit 31 and a second drive circuit 32 are provided.

The high potential input terminal 11 and the low potential input terminal 12 are connected to the DC power supply 2 . The high potential output terminal 13 and the low potential output terminal 14 are connected to the DC load 4 . The low potential output terminal 14 is electrically connected to the low potential input terminal 12 . The power supply device 10 converts the DC power supplied from the DC power supply 2 via the high potential input terminal 11 and the low potential input terminal 12 into another DC power, and converts the converted DC power to the high potential output terminal 13 and the low potential input terminal 12 . It is supplied to the DC load 4 via the potential output terminal 14 .

The first switching element 21 is provided between the high potential input terminal 11 and the low potential input terminal 12 . The second switching element 22 is provided between the first switching element 21 and the low potential input terminal 12 . In other words, the first switching element 21 and the second switching element 22 are connected in series between the high potential input terminal 11 and the low potential input terminal 12 .

The first switching element 21 has electrodes 21a to 21c. The second switching element 22 has electrodes 22a-22c. The electrode 21 a of the first switching element 21 is connected to the high potential input terminal 11 . The electrode 21 b of the first switching element 21 is connected to the electrode 22 a of the second switching element 22 . An electrode 22 b of the second switching element 22 is connected to the low potential input terminal 12 .

The first switching element 21 and the second switching element 22 are, for example, n-channel FETs. For example, electrodes 21a, 22a are drains, electrodes 21b, 22b are sources, and electrodes 21c, 22c are gates. However, the first switching element 21 and the second switching element 22 may be, for example, p-channel FETs or bipolar transistors. Also, the first switching element 21 and the second switching element 22 may be elements in which a GaN-FET and a Si-MOS are cascode-connected. More specifically, a GaN element and a Si element may be connected in series, and the GaN element is always on, and the Si element is controlled by inputting a gate signal to switch on/off.

The 1st switching element 21 and the 2nd switching element 22 contain the semiconductor material in any one of Si, SiC, and GaN, for example. In other words, the first switching element 21 and the second switching element 22 are formed using a semiconductor material such as Si, SiC, or GaN. SiC or GaN is particularly suitable for the semiconductor material of the first switching element 21 and the second switching element 22 . As a result, the switching frequencies of the first switching element 21 and the second switching element 22 can be made higher than when Si is used as the semiconductor material.

One end 24 a of the inductor 24 is connected to a connection point between the first switching element 21 and the second switching element 22 . In other words, one end 24 a of the inductor 24 is connected to the electrode 21 b of the first switching element 21 and the electrode 22 a of the second switching element 22 . The other end 24 b of the inductor 24 is connected to the high potential output terminal 13 .

One end 26 a of the smoothing capacitor 26 is connected to the other end of the inductor 24 and the high potential output terminal 13 . The other end 26 b of the smoothing capacitor 26 is connected to the low potential output terminal 14 . In other words, smoothing capacitor 26 is provided in parallel with DC load 4 between high potential output terminal 13 and low potential output terminal 14 .

The power supply device 10 is a so-called step-down chopper circuit. The second switching element 22 functions as a rectifying element of the step-down chopper circuit. The power supply device 10 steps down the DC power supplied from the DC power supply 2 and supplies the stepped-down DC power to the DC load 4 .

The first drive circuit 31 is connected to the electrode 21 c of the first switching element 21 and controls switching of the first switching element 21 . The first drive circuit 31 controls switching of the first switching element 21 based on the voltage of the inductor 24 and the current flowing through the first switching element 21 when the first switching element 21 is turned on.

The second drive circuit 32 is connected to the electrode 22 c of the second switching element 22 and controls switching of the second switching element 22 . The second drive circuit 32 controls switching of the second switching element 22 based on the voltage of the inductor 24 and the current flowing through the second switching element 22 when the second switching element 22 is turned on.

The first drive circuit 31 and the second drive circuit 32 are, for example, a control IC (Integrated Circuit) for a critical current mode power factor correction circuit. More specifically, for the first drive circuit 31 and the second drive circuit 32, for example, MC33262 manufactured by ON Semiconductor, TB6819AFG manufactured by Toshiba, or the like is used. However, the first drive circuit 31 and the second drive circuit 32 are not limited to this, and may be any circuit capable of controlling the switching of the first switching element 21 and the second switching element 22 .

The power supply device 10 further includes a first auxiliary winding 41 , a second auxiliary winding 42 , a first current detection resistor 51 and a second current detection resistor 52 .

The first auxiliary winding 41 is connected to the first drive circuit 31 . The second auxiliary winding 42 is connected to the second drive circuit 32 . The first auxiliary winding 41 and the second auxiliary winding 42 are connected, for example, to terminals for detecting zero current of a control IC for a critical current mode type power factor correction circuit.

The first auxiliary winding 41 is magnetically coupled with the inductor 24 to input a voltage corresponding to the voltage of the inductor 24 to the first drive circuit 31 . The first drive circuit 31 detects the voltage of the inductor 24 based on the voltage input from the first auxiliary winding 41 . More specifically, the first drive circuit 31 detects the voltage on the one end 24 a side of the inductor 24 based on the voltage input from the first auxiliary winding 41 .

The second auxiliary winding 42 is magnetically coupled with the inductor 24 to input a voltage corresponding to the voltage of the inductor 24 to the second drive circuit 32 . The second drive circuit 32 detects the voltage of the inductor 24 based on the voltage input from the second auxiliary winding 42 . More specifically, the second drive circuit 32 detects the voltage on the one end 24a side of the inductor 24 based on the voltage input from the second auxiliary winding 42 .

The polarity of the second auxiliary winding 42 is inverted with respect to the polarity of the first auxiliary winding 41 . In this example, the polarity of the first auxiliary winding 41 is in phase with the inductor 24 and the polarity of the second auxiliary winding 42 is in phase with the inductor 24 . Therefore, in this example, when the voltage at one end 24 a of the inductor 24 is high, a low voltage is input to the first drive circuit 31 and a high voltage is input to the second drive circuit 32 . Conversely, when the voltage at one end 24a of the inductor 24 is low, a high voltage is input to the first drive circuit 31 and a low voltage is input to the second drive circuit 32. FIG.

A first current detection resistor 51 is provided between the low potential input terminal 12 and the low potential output terminal 14 . The first current detection resistor 51 is connected with the first drive circuit 31 . The first current detection resistor 51 is connected to, for example, a current detection terminal of a control IC for a critical current mode power factor correction circuit. Thus, the first drive circuit 31 detects the current flowing through the first switching element 21 when the first switching element 21 is turned on based on the voltage input from the first current detection resistor 51 . In other words, the current that flows through the first switching element 21 when the first switching element 21 is turned on is the current that flows through the inductor 24 and the DC load 4 when the first switching element 21 is turned on.

The second current detection resistor 52 is provided between the electrode 22b of the second switching element 22 and the low potential input terminal 12 (low potential output terminal 14). The second current detection resistor 52 is connected with the second drive circuit 32 . The second current detection resistor 52 is connected to, for example, a current detection terminal of a control IC for a critical current mode power factor correction circuit. Thereby, the second drive circuit 32 detects the current flowing through the second switching element 22 when the second switching element 22 is turned on based on the voltage input from the second current detection resistor 52 .

However, the method of detecting the voltage of the inductor 24 and the method of detecting the current flowing through the first switching element 21 by the first driving circuit 31 are not limited to the above, and any method that can appropriately detect them may be used. Similarly, the method of detecting the voltage of the inductor 24 and the method of detecting the current flowing through the second switching element 22 by the second driving circuit 32 are not limited to the above, and any method that can appropriately detect them may be used.

For example, if the logic can be inverted inside the first drive circuit 31 and the second drive circuit 32, the polarity of the second auxiliary winding 42 should be the same as the polarity of the first auxiliary winding 41. good too. Thus, the polarity of the second auxiliary winding 42 does not necessarily have to be reversed with respect to the polarity of the first auxiliary winding 41 .

2(a) to 2(g) are explanatory diagrams schematically showing an example of the operation of the power supply device according to the embodiment.
3A to 3E are graph diagrams schematically showing an example of the operation of the power supply device according to the embodiment.
In addition, in FIGS. 2A to 2G, the configuration of the power supply device 10 is shown in a simplified manner for the sake of easy understanding. 2A to 2G, the parasitic capacitance 21q between the electrodes 21a and 21b of the first switching element 21 and the parasitic capacitance 22q between the electrodes 22a and 22b of the second switching element 22 are is illustrated.

FIG. 3A schematically shows an example of characteristics of the current IL flowing through the inductor 24. FIG. FIG. 3B schematically shows an example of characteristics of the voltage VL1 of the inductor 24 detected by the first drive circuit 31. As shown in FIG.
FIG. 3(c) schematically shows an example of characteristics of the voltage VL2 of the inductor 24 detected by the second drive circuit 32. As shown in FIG. As mentioned above, the polarity of the second auxiliary winding 42 is reversed with respect to the polarity of the first auxiliary winding 41 . Therefore, the voltage VL2 appears as an inverted signal with respect to the voltage VL1. In addition, since the voltages of the first auxiliary winding 41 and the second auxiliary winding 42 change relatively greatly, the voltages VL1 and VL2 of the first driving circuit 31 and the second driving circuit 32 are higher than the predetermined voltage. It has a clamping function that clamps it so that it does not.
FIG. 3D schematically shows an example of characteristics of the voltage Vg1 of the control signal input from the first drive circuit 31 to the electrode 21c of the first switching element 21. As shown in FIG.
FIG. 3(e) schematically shows an example of characteristics of the voltage Vg2 of the control signal input from the second drive circuit 32 to the electrode 22c of the second switching element 22. As shown in FIG. The voltage Vg1 and the voltage Vg2 are, for example, gate voltages.

2A and timing t1 in FIG. 3, in the operation of the power supply device 10, first, the first driving circuit 31 turns on the first switching element 21, and the second driving circuit 32 turns on the first switching element 21. 2 The switching element 22 is turned off. The first drive circuit 31 turns on the first switching element 21 by, for example, setting the voltage Vg1 to Hi, and the second driving circuit 32 turns on the second switching element 22 by, for example, setting the voltage Vg2 to Lo. Turn off.

When the first switching element 21 is turned on and the second switching element 22 is turned off, the positive current supplied from the DC power supply 2 flows through the inductor 24 and the inductor 24 is charged with the positive current. Therefore, the current IL of the inductor 24 increases as indicated by timings t1 to t2 in FIG.

Here, the positive current is the current that flows in the inductor 24 from the one end 24a to the other end 24b, and the negative current is the current that flows in the inductor 24 from the other end 24b to the one end 24a. .

When the first switching element 21 is turned on and the second switching element 22 is turned off, a high voltage based on the DC power supply 2 is applied to the one end 24a side of the inductor 24 . Therefore, in this case, the voltage VL1 that is in phase with the inductor 24 is low, and the voltage VL2 that is in phase with the inductor 24 is high.

After the first drive circuit 31 turns on the first switching element 21, based on the voltage input from the first current detection resistor 51, the positive current IL flowing through the inductor 24 reaches the upper limit value UL. Determine whether or not

2B and timing t2 in FIG. 3, the first drive circuit 31 changes the voltage Vg1 to Hi in response to the positive current IL flowing through the inductor 24 reaching the upper limit value UL. to Lo to turn off the first switching element 21 .

When the first switching element 21 is switched from the ON state to the OFF state as shown in timings t2 to t3 in FIG. 3, the current IL flowing through the inductor 24 decreases, and the positive current energy stored in the inductor discharged. Along with this, the voltage on the one end 24a side of the inductor 24 also decreases. Therefore, voltage VL1 increases and voltage VL2 decreases.

After turning off the second switching element 22, the second drive circuit 32 determines whether or not the voltage VL2 has become equal to or less than a predetermined threshold value Vth2 based on the voltage input from the second auxiliary winding 42. .

As shown in FIG. 2C and timing t3 in FIG. 3, the second drive circuit 32 switches the voltage Vg2 from Lo to Hi in response to the voltage VL2 becoming equal to or lower than the predetermined threshold value Vth2, The second switching element 22 is turned on. More specifically, the second drive circuit 32 determines that the voltage at the one end 24a of the inductor 24 has become equal to or less than a predetermined value when the voltage VL2 input from the second auxiliary winding 42 has become equal to or less than the threshold value Vth2. , turns on the second switching element 22 .

When the second switching element 22 is turned on, the potential of the one end 24a of the inductor 24 becomes substantially the same as the potential of the low potential input terminal 12 (for example, the ground potential), and the positive current stored in the inductor 24 is reduced. More energy is discharged. Therefore, voltage VL1 further increases and voltage VL2 further decreases.

2(d) and timing t4 in FIG. 3, when the positive current energy stored in the inductor 24 is completely discharged, the negative current flows through inductor 24, charging inductor 24 with a negative current. Thus, the second drive circuit 32 causes a negative current to flow through the inductor 24 based on the charge accumulated in the smoothing capacitor 26 by turning on the second switching element 22 .

After the second drive circuit 32 turns on the second switching element 22, based on the voltage input from the second current detection resistor 52, the negative current IL flowing through the inductor 24 reaches the lower limit value LL. Determine whether or not

2(e) and timing t5 in FIG. 3, the second drive circuit 32 changes the voltage Vg2 to Hi in response to the negative current IL flowing through the inductor 24 reaching the lower limit value LL. to Lo to turn off the second switching element 22 .

In this manner, the first drive circuit 31 and the second drive circuit 32 turn the first switching element 21 on and the second switching element 22 off, and then turn the first switching element 21 off and turn the second switching element 21 off. The first switching element 21 and the second switching element 22 are turned off before turning the element 22 on and turning the first switching element 21 on again.

When the second switching element 22 is switched from the ON state to the OFF state, the negative current energy stored in the inductor 24 is discharged and the parasitic capacitance 22q of the second switching element 22 is charged. Along with this, when the second switching element 22 is switched from the ON state to the OFF state, the voltage on the one end 24a side of the inductor 24 increases. Therefore, the voltage VL1 decreases and the voltage VL2 increases, as indicated by timings t5 to t7 in FIG.

As shown in FIG. 2(f) and timing t6 in FIG. 3, when the charging of the parasitic capacitance 22q of the second switching element 22 is completed, the negative current flows back to the DC power supply 2. As a result, the energy of the negative current stored in the inductor 24 is further discharged, and the voltage on the one end 24a side of the inductor 24 further increases. , further increasing.

After turning off the first switching element 21, the first drive circuit 31 determines whether or not the voltage VL1 has become equal to or less than a predetermined threshold value Vth1 based on the voltage input from the first auxiliary winding 41. .

As shown in FIG. 2G and timing t7 in FIG. 3, the first drive circuit 31 switches the voltage Vg1 from Lo to Hi in response to the voltage VL1 becoming equal to or lower than the predetermined threshold value Vth1, The first switching element 21 is turned on. More specifically, when the voltage VL1 input from the first auxiliary winding 41 becomes equal to or less than the threshold Vth1, the first drive circuit 31 determines that the voltage at the one end 24a of the inductor 24 becomes equal to or greater than a predetermined value. , the first switching element 21 is turned on. This completes the discharge of the energy of the negative current stored in the inductor 24, returning to the state of FIG. 2(a).

The power supply device 10 repeats the above operation. As a result, the voltage of the DC power supply 2 is stepped down, and the stepped-down DC power is supplied to the DC load 4 . In the power supply device 10, for example, the converted voltage value can be set by setting values such as the upper limit value UL and the lower limit value LL. The values such as the upper limit value UL and the lower limit value LL are, for example, the voltage of the feedback terminal of the output voltage of the control IC for the critical current mode type power factor correction circuit and the terminal for detecting the full-wave rectified voltage waveform of the AC voltage. can be set by adjusting

In the power supply device 10, before switching the first switching element 21 from the OFF state to the ON state, a negative current flows through the inductor 24, and based on the energy of the negative current stored in the inductor 24, the second switching element 22 is charging the parasitic capacitance 22q. As a result, when the first switching element 21 is switched from the OFF state to the ON state, it is possible to suppress the through current flowing through the low potential input terminal 12 via the parasitic capacitance 22q of the second switching element 22. can be done. Thereby, in the power supply device 10, the switching loss caused by the through current can be suppressed. In the power supply device 10, the turn-on loss of the first switching element 21 can be reduced.

That is, the power supply device 10 can perform TCM control. In the power supply device 10, TCM control can be realized only by the first drive circuit 31 and the second drive circuit 32 without using an expensive microcomputer capable of digital control. More specifically, TCM control can be realized only by using two control ICs for a critical current mode type power factor correction circuit, which are general-purpose ICs. Thus, in the power supply device 10, TCM control can be realized with a simple configuration. Therefore, in the power supply device 10, suppression of switching loss can be realized with a simple configuration. In the power supply device 10, for example, by using a general-purpose IC, TCM control can be realized at low cost. That is, in the power supply device 10, both suppression of switching loss and cost reduction can be achieved.

In the power supply device 10 , the polarity of the second auxiliary winding 42 is reversed with respect to the polarity of the first auxiliary winding 41 . Thereby, in each of the first drive circuit 31 and the second drive circuit 32, the switching element can be switched from the off state to the on state when the voltage becomes equal to or less than the threshold. Therefore, the same type of control IC can be used for the first drive circuit 31 and the second drive circuit 32, and the configuration of the power supply device 10 can be simplified. The manufacturing cost of the power supply device 10 can be further suppressed.

For example, when the first drive circuit 31 is configured to switch the first switching element 21 from the off state to the on state when the voltage VL1 becomes equal to or higher than the threshold value Vth1, the second auxiliary winding The polarity of 42 may be the same as the polarity of the first auxiliary winding 41 .

While several embodiments and examples of the invention have been described, these embodiments or examples are provided by way of example and are not intended to limit the scope of the invention. These novel embodiments or examples can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the spirit of the invention. These embodiments, examples, and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

2 DC power supply 4 DC load 10 Power supply device 11 High potential input terminal 12 Low potential input terminal 13 High potential output terminal 14 Low potential output terminal 21 First switching element 22 Second switching element 24 Inductor , 26 smoothing capacitor, 31 first drive circuit, 32 second drive circuit, 41 first auxiliary winding, 42 second auxiliary winding, 51 first current detection resistor, 52 second current detection resistor

Claims (6)

a high-potential input terminal and a low-potential input terminal connected to a DC power supply;
a high-potential output terminal and a low-potential output terminal connected to a DC load;
a first switching element provided between the high potential input terminal and the low potential input terminal;
a second switching element provided between the first switching element and the low potential input terminal;
an inductor having one end connected to a connection point between the first switching element and the second switching element and the other end connected to the high potential output terminal;
a smoothing capacitor having one end connected to the other end of the inductor and the high potential output terminal, and the other end connected to the low potential output terminal;
a first drive circuit that controls switching of the first switching element based on the voltage of the inductor and the current flowing through the first switching element;
a second drive circuit for controlling switching of the second switching element based on the voltage of the inductor and the current flowing through the second switching element;
with
The first driving circuit and the second driving circuit turn on the first switching element and turn off the second switching element, and then turn off the first switching element and turn on the second switching element. and turning off each of the first switching element and the second switching element before turning on the first switching element again. The first drive circuit turns on the first switching element, causes a positive current to flow through the inductor from the one end of the inductor to the other end of the inductor, and then causes the positive current to flow through the inductor. is detected, and the first switching element is turned off in response to the positive current reaching the upper limit,
The second drive circuit detects the voltage at the one end of the inductor when the second switching element is turned off, and detects the voltage at the one end of the inductor after the first switching element is turned off. When the voltage on the side becomes equal to or less than a predetermined value, the second switching element is turned on, and based on the charge accumulated in the smoothing capacitor, a negative current directed in the opposite direction to the positive current is generated. flow through the inductor;
The second drive circuit detects the negative current flowing through the inductor after turning on the second switching element, and detects the negative current flowing through the inductor, and switches the second switching element in response to the negative current reaching a lower limit value. is turned off, and
The first drive circuit detects the voltage at the one end of the inductor when the first switching element is turned off, and detects the voltage at the one end of the inductor after the first switching element is turned off. 2. The power supply device according to claim 1, wherein the first switching element is turned on when the voltage on the side becomes equal to or higher than a predetermined value. a first auxiliary winding connected to the first drive circuit, magnetically coupled with the inductor, and inputting a voltage corresponding to the voltage of the inductor to the first drive circuit;
a second auxiliary winding connected to the second drive circuit, magnetically coupled to the inductor, and inputting a voltage corresponding to the voltage of the inductor to the second drive circuit;
further comprising
The first drive circuit detects the voltage at the one end of the inductor based on the voltage input from the first auxiliary winding,
3. The power supply device according to claim 2, wherein the second drive circuit detects the voltage at the one end of the inductor based on the voltage input from the second auxiliary winding. The polarity of the second auxiliary winding is inverted with respect to the polarity of the first auxiliary winding,
the first drive circuit determines that the voltage at the one end of the inductor has reached a predetermined value or higher when the voltage input from the first auxiliary winding is lower than a threshold;
4. The power supply according to claim 3, wherein the second drive circuit determines that the voltage at the one end of the inductor has become equal to or less than a predetermined value when the voltage input from the second auxiliary winding becomes equal to or less than a threshold. Device. The power supply device according to any one of claims 1 to 4, wherein the first switching element and the second switching element include a semiconductor material selected from Si, SiC, and GaN. The power supply device according to any one of claims 1 to 5, wherein the first drive circuit and the second drive circuit are control ICs for a critical current mode power factor correction circuit.

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