TWI433443B - Interleaved forward converter with inherent demagnetizing - Google Patents

Description

Misaligned forward conversion device with magnetic reset

The invention relates to the technical field of a forward conversion device, in particular to a phase-shifting conversion device with magnetic reset.

In recent years, the forward converter has been widely used in the power supply industry due to its simple architecture and high efficiency. Despite its long history, forward converters are still evolving. In fact, in order to meet different demand applications, many trade-offs between switch stress and transformer reset are still necessary. Therefore, topology changes and innovations of new forward converters continue to appear. .

Many forward converters have different ways of magnetic reset due to different transformer magnetic reset schemes. In the conventional forward converter, a third degaussing coil is used, but this method increases the voltage stress applied to the metal oxide semiconductor field effect transistor (MOSFET), and the voltage stress is about 2.6×. V _{in max} , where V _{in max} is the maximum input voltage.

Another magnetic reset method uses an RCD network to reset the transformer, which limits the voltage stress on the MOSFET to 2.0 × V _{in max} , but the power dissipation on the resistor greatly reduces the efficiency of the converter.

In order to solve the problem of excessive power consumption caused by using the RCD network, another conventional technique uses an LCDD resonant reset circuit instead of the RCD network, so that the magnetization energy can be regenerated and the voltage stress on the MOSFET can be limited to 2.0×. V _{in max} below, however, the size of the inductor is too large and the additional conduction losses due to resonance, thus limiting the application of the LCDD resonant reset circuit.

Another conventional method uses resonant reset, which has a simple circuit architecture but is difficult to maintain for optimal reset conditions and load conditions for the entire line.

Another conventional method uses a two-switch forward converter that requires an additional MOSFET transistor and a high-side gate driver to limit the voltage stress on the MOSFET to V. _{In max} , but its maximum duty-cycle cannot exceed the 50% limit.

Another conventional approach is to use a ZVS soft switch to achieve an active clamp reset and maintain the voltage stress on the MOSFET below 1.3 x Vin _max . But it requires an auxiliary MOSFET and the use of an inductor, which increases the conduction losses by 30%-50%.

Although the topology of forward converters has evolved over the years, simple design, low voltage stress, and lossless reset mechanisms are still an important issue. Therefore, the wrong phase forward conversion device with magnetic reset is still known. There is room for improvement.

SUMMARY OF THE INVENTION The main object of the present invention is to provide a phase-shifting device with a magnetic reset that can directly recover the magnetizing inductance energy so that the converter does not require an additional magnetic reset circuit. At the same time, through the clamp diode to the main The voltage on the switch is clamped to reduce the withstand voltage of the switch, so no additional clamp circuit is required.

According to a feature of the present invention, the present invention provides a phase-shifting conversion device with magnetic reset, comprising a first forward converter cell and a second forward converter lattice. And a first capacitor C1. The first forward conversion crystal lattice has a first switching device, a first diode, a first transformer, a third diode, a fourth diode, and a first output inductor. The second forward conversion crystal lattice has a second switching device, a second diode, a second transformer, a fifth diode, a sixth diode, and a second output inductor. The first capacitor is coupled to the first forward conversion crystal lattice and the second forward conversion crystal lattice to store/release energy of an input power source; wherein the first switching device and the first transformer are once The first switching inductance and the second output inductance of the second switching device are connected in series to a load.

1 is a circuit diagram of one embodiment of a magnetically reset phase-shifted forward converter 100 of the present invention. The magnetically reset phase-shifted forward converter device 100 includes a first forward converter cell 110, a second forward converter cell 120, and a first capacitor C1.

The first forward conversion lattice 110 has a first switching device S1, a first diode D1, a first transformer T1, a third diode D3, a fourth diode D4, and a first switching device S1. The first output inductor Lo1.

The second forward conversion crystal lattice 120 has a second switching device S2, a second diode D2, a second transformer T2, a fifth diode D5, a sixth diode D6, and a The second output inductor Lo2.

The first capacitor C1 is connected to the first forward conversion lattice 110 and the second forward conversion lattice 120 to store/release energy of an input power source Vin; wherein the first switching device S1 The primary side of the first transformer T1, the second switching device S2, and the primary side of the second transformer T2 are connected in series, and the first output inductor Lo1 and the second output inductor Lo2 are connected in parallel to a load. The load includes an output capacitor Co and a load resistor R _L .

A first end S11 of the first switching device S1 is connected to the input power source Vin. The negative end of the first diode D1 is connected to a second end S12 of the first switching device S1 and a first end T111 of the primary side of the first transformer T1. The positive terminal of the first diode T1 is connected to a low potential (Gnd), and a second terminal T112 of the primary side of the first transformer T1 is connected to the positive terminal of the first capacitor C1 and the second transformer T2. A first terminal T211 of the primary side, the negative terminal of the first capacitor C1 is connected to the low potential (Gnd). A second end T212 of the primary side of the second transformer T2 is connected to the positive end of the second diode D2 and a first end S21 of the second switching device S2, and a second of the second switching device S2 Terminal S22 is connected to the low potential (Gnd). The negative terminal of the second diode D2 is connected to a first end S11 of the first switching device S1.

A first end T121 of the second side of the first transformer T1 is connected to the positive end of the third diode D3, and a negative end of the third diode D3 is connected to the negative end of the fourth diode D4. And a first end L11 of the first output inductor Lo1, a second end L12 of the first output inductor Lo1 is connected to the load, and a positive end of the fourth diode D4 is connected to the other end of the load and the A second end T122 of the secondary side of the first transformer T1.

A first end T221 of the second side of the second transformer T2 is connected to the positive end of the fifth diode D5, and a negative end of the fifth diode D5 is connected to the negative end of the sixth diode D6. And a first end L21 of the second output inductor Lo2, a second end L22 of the second output inductor Lo2 is connected to the load, and a positive end of the sixth diode D6 is connected to the other end of the load and the A second end T222 of the secondary side of the second transformer T2.

As shown in FIG. 1, the first switching device S1, the primary side of the first transformer T1, the second switching device S2, and the primary side of the second transformer T2 are connected in series, and the positive end of the first capacitor C1 is connected. The voltage is Vin/2, where Vin is the voltage value of the input power source. Since the voltage applied to the positive terminal of the first capacitor C1 is only Vin/2, the first capacitor C1 can be fabricated using a material having a low withstand voltage, which can save considerable cost.

A third end of the first switching device S1 is coupled to a first control signal to control the opening and closing of the first switching device S1. A third end of the second switching device S2 is coupled to a second control signal to control the opening and closing of the second switching device S2. The first control signal is interleaved with the second control signal.

FIG. 2 to FIG. 5 are schematic diagrams showing currents of the first switching device S1 and the second switching device S2 according to the present invention when turned on and off. As shown in FIG. 2, when the first control signal controls the first switching device S1 to be turned on, since the first control signal and the second control signal are interleaved, the second switching device S2 is shut down. The current of the input power source Vin charges the first capacitor C1 via the first switching device S1 and the primary side of the first transformer T1. At this time, the secondary side of the first transformer T1 stores the first output inductor Lo1 via the third diode D3.

As shown in FIG. 3, when the first control signal controls the first switching device S1 to be off, although the first control signal and the second control signal are out of phase, the first control signal is turned off and the first control signal is turned off. There will be a time gap between the two control signals being turned on. At this time, the current of the magnetic inductor of the primary side of the first transformer T1 is reduced to 0 via the first capacitor C1 and the first diode D1 to generate a magnetic reset effect. When the first control signal controls the first switching device S1 to be off, the first output inductor Lo1 releases the load.

As shown in FIG. 4, when the second control signal controls the second switching device S2 to be turned on, the first control signal is out of phase with the second control signal, and the first control signal is turned off and the second control is The first switching device S1 is turned off, and the energy stored in the first capacitor C1 is released via the primary side of the second transformer T2 and the second switching device S2. The second transformer T2 is turned off. The secondary side stores the second output inductor L02 via the fifth diode D5.

As shown in FIG. 5, when the second control signal controls the second switching device S2 to be off, the current of the magnetic inductor of the primary side of the second transformer T2 is decreased via the first diode D2. Is 0 to produce a magnetic reset effect. And when the second control signal controls the second switching device S2 to be off, the second output inductor Lo2 releases the load.

According to the foregoing circuit operation analysis, the technology of the present invention can directly recover the magnetizing inductance energy by using the clamp diode, so that the converter does not need an additional magnetic reset circuit, and the voltage component of the power component can be clamped, so that the converter has a comparison. High conversion efficiency, no need to design the vibration-damping circuit and low cost.

In summary, the magnetically reset phase-shifted forward converter 100 of the present invention includes two active switches S1, S2, two transformers T1, T2, two clamp diodes D1, D2, and four The rectifier diodes D3, D4, D5, and D6, the front stage storage capacitor C1, the output filter capacitor Co, and the output inductors Lo1 and Lo2. The magnetically reset phase-shifted forward converter 100 of the present invention uses two sets of forward converters for symmetrical operation, so that the energy storage capacitor of the preceding stage is one-half of the input voltage Vin. The active switches S1 and S2 are out of phase control, so that the output has a lower voltage chopping. When the active switches S1 and S2 are turned off, the magnetizing energy of the transformers T1 and T2 can be magnetically reset through the clamp diodes D1 and D2, and through the clamp diodes D1 and D2 on the active switches S1 and S2. The voltage is clamped to reduce the withstand voltage of the switches S1 and S2, so no additional clamping circuit is needed, and the switches S1 and S2 do not need to be manufactured by a high-pressure process, which can effectively save costs. The magnetically reset phase-shifting forward conversion device 100 of the present invention can be applied to medium and high power personal computer power supplies, liquid crystal television power supplies, medium and high power communication power supplies and the like.

From the above, it can be seen that the present invention is extremely useful in terms of its purpose, means, and efficacy, both of which are different from those of the prior art. It should be noted that the various embodiments described above are merely illustrative for ease of explanation, and the scope of the invention is intended to be limited by the scope of the claims.

100‧‧‧Wrong phase forward conversion device with magnetic reset

110‧‧‧First forward conversion lattice

120‧‧‧Second directional conversion lattice

C1‧‧‧first capacitor

S1‧‧‧ first switching device

D1‧‧‧First Diode

T1‧‧‧ first transformer

D3‧‧‧ third diode

D4‧‧‧ fourth diode

Lo1‧‧‧first output inductor

S2‧‧‧Second switching device

D2‧‧‧ second diode

T2‧‧‧second transformer

D5‧‧‧ fifth diode

D6‧‧‧ sixth diode

Lo2‧‧‧second output inductor

Vin‧‧‧Input power supply

Co‧‧‧ output capacitor

R _L ‧‧‧Load resistor

S11, T111, T211, S21, T121, L11, T221, L21‧‧‧ first end

S12, T112, T212, S22, T122, L12, T222, L22‧‧‧ second end

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a circuit diagram of a magnetically reset phase-shifted forward converter of the present invention.

2 to 5 are schematic views of currents when the switching device of the present invention is turned on and off.

100. . . Misaligned forward conversion device with magnetic reset

110. . . First forward conversion lattice

120. . . Second forward conversion lattice

C1. . . First capacitor

S1. . . First switching device

D1. . . First diode

T1. . . First transformer

D3. . . Third diode

D4. . . Fourth diode

Lo1. . . First output inductor

S2. . . Second switching device

D2. . . Second diode

T2. . . Second transformer

D5. . . Fifth diode

D6. . . Sixth diode

Lo2. . . Second output inductor

Vin. . . Input power

Co. . . Output capacitor

R _L . . . Load Resistance

S11, T111, T211, S21, T121, L11, T221, L21. . . First end

S12, T112, T212, S22, T122, L12, T222, L22. . . Second end

Claims (11)

A phase-shifting conversion device with magnetic reset, comprising: a first forward conversion lattice having a first switching device, a first diode, a first transformer, and a third a diode, a fourth diode, and a first output inductor, the first switching device and the first diode are directly connected to a primary side of the first transformer, the third diode and the fourth The diode is directly connected to the secondary side of the first transformer and the first output inductor; a second forward conversion lattice has a second switching device, a second diode, a second transformer, a fifth diode, a sixth diode, and a second output inductor, the second switching device and the second diode are directly connected to the primary side of the second transformer, the fifth diode and The sixth diode is directly connected to the secondary side of the second transformer and the second output inductor; and a first capacitor is coupled to the first forward conversion lattice and the second forward conversion lattice To store/release energy of an input power source; wherein the first switching device, the first transformer The primary side, the second switching device, and the primary side of the second transformer are connected in series, and the first output inductor and the second output inductor are connected in parallel to a load. The phase-shifting device with a magnetic reset as described in claim 1, wherein a first end of the first switching device is connected to the input power source, and a negative end of the first diode Connected to a second end of the first switching device and a first end of the primary side of the first transformer, the positive terminal of the first diode is connected to a low potential, the first voltage transformation a second end of the primary side of the device is connected to a positive end of the first capacitor and a first end of the primary side of the second transformer, the negative end of the first capacitor is connected to the low potential, the second transformer a second end of the primary side is connected to the positive end of the second diode and a first end of the second switching device, and a second end of the second switching device is connected to the low potential, the first two A positive end of the pole body is coupled to the first end of the first switching device. The phase-shifting device with a magnetic reset as described in claim 2, wherein a first end of the secondary side of the first transformer is connected to a positive end of the third diode, a negative end of the third diode is connected to a negative end of the fourth diode and a first end of the first output inductor, and a second end of the first output inductor is connected to the load, the fourth a positive end of the diode is connected to the other end of the load and a second end of the secondary side of the first transformer, and a first end of the secondary side of the second transformer is connected to the fifth diode a positive end, a negative end of the fifth diode is connected to a negative end of the sixth diode and a first end of the second output inductor, and a second end of the second output inductor is connected to the load, The positive end of the sixth diode is connected to the other end of the load and a second end of the secondary side of the second transformer. The phase-shifting device with a magnetic reset as described in claim 3, wherein the first switching device, the primary side of the first transformer, the second switching device, and the second transformer The primary side is connected in series, and the voltage of the positive terminal of the first capacitor is Vin/2, wherein Vin is the voltage value of the input power source. The third phase of the first switching device is connected to a first control signal to control the first switching device, as described in claim 4, wherein the third switching end of the first switching device is connected to the first switching device. Turning on and off, a third end of the second switching device is connected to a second control signal to control the opening and closing of the second switching device, and the first control signal is out of phase with the second control signal. The phase-shifting device with a magnetic reset as described in claim 5, wherein when the first control signal controls the first switching device to be turned on, the current of the input power source passes through the first The switching device and the primary side of the first transformer charge the first capacitor, and the secondary side of the first transformer stores the first output inductor via the third diode. The phase-shifting device with a magnetic reset as described in claim 6, wherein when the first control signal controls the first switching device to be off, the magnetization of the primary side of the first transformer The current of the inductor is reduced to zero via the first capacitor and the first diode to generate a magnetic reset effect. The out-of-phase forward conversion device with magnetic reset as described in claim 7, wherein the first output inductor releases the load when the first control signal controls the first switching device to be off can. The phase-shifting device with a magnetic reset as described in claim 8 , wherein when the second control signal controls the second switching device to be turned on, the energy stored by the first capacitor is The primary side of the second transformer, the second switching device is released, the second variable voltage The secondary side of the device stores energy to the second output inductor via the fifth diode. The phase-shifting device with magnetic reset according to claim 9, wherein when the second control signal controls the second switching device to be off, the magnetization of the primary side of the second transformer The current of the inductor is reduced to zero via the first diode to produce a magnetic reset effect. The phase-shifting device with a magnetic reset as described in claim 10, wherein when the second control signal controls the second switching device to be off, the second output inductor releases the load can.