TWI425753B - Forward-flyback converter with lossless snubber circuit - Google Patents

Description

Forward-return converter with lossless vibration-damping circuit

The present invention relates to a forward-return type converter, and more particularly to a forward-return type converter having a lossless vibration damping circuit.

With the diversification of the use of electronic products, the use of power converters has become diverse, and the thin and light is always the goal pursued by electronic products. Therefore, increasing the operating frequency and streamlining the circuit architecture has become the main direction for reducing the size of the power converter.

Figure 1 shows a conventional forward-return converter. The forward-return type converter has the advantages of low output chopping, no need to de-magnetic winding, simple structure and easy driving, but the conventional forward-return type converter must be provided with an output inductor Lo, resulting in an increase in product volume. The cost is increased.

Increasing the operating frequency can reduce the size of the circuit and save the cost of components, but it will also increase the switching loss of the switch, so that the efficiency of the power converter is reduced. At this time, the problem can be reduced by the lossless vibration-damping circuit. Bad influence. In addition, the feedback loop can be effectively streamlined by the isolated coil feedback mechanism to reduce the complexity of the feedback circuit in the circuit. Figure 2 shows a conventional flyback converter with a lossless damper circuit. The lossless vibration damping circuit has a mechanism for storing leakage energy, which can reduce the switching cutoff The voltage stress of the time and return the stored energy to the input power terminal. Figure 3 shows a conventional flyback converter with isolated coil feedback. The isolated coil feedback circuit has an isolated voltage feedback mechanism and can be additionally provided with an auxiliary power supply.

Therefore, how to integrate the lossless vibration-damping circuit and the isolated coil feedback into the circuit to reduce the switching loss and voltage stress of the switch and recover the energy of the leakage inductance, and at the same time achieve the purpose of simplifying the circuit structure and reducing the number of components, An important issue for further improvement of the converter.

In view of the above problems of the prior art, one of the objects of the present invention is to provide a forward-return type converter with a lossless vibration-damping circuit to solve the problem that the conventional converter has to add an output inductor, resulting in an increase in circuit volume. The problem of increased costs.

According to another object of the present invention, a forward-return type converter having a lossless vibration damping circuit is proposed. The converter includes a forward-return type converter and a vibration recovery feedback network. The forward-return type converter has a transformer having an input power terminal and a switch in a loop on the primary side of the transformer, an inductor in a loop on a secondary side of the transformer, and an inductor in a loop on the primary side And a leaky feeling. The vibration-recovery feedback network can store the energy of the leakage inductance in the primary circuit, and use the transformer to transmit energy back to the input power terminal, so as to reduce the voltage stress at both ends of the switch and the loss caused by the switching of the switch. And obtaining a feedback voltage on the secondary side of the transformer, and determining the switching of the switch by the feedback voltage.

According to still another object of the present invention, a forward-return type converter is provided, which includes a transformer, a first inductor, a leakage inductance, a second inductance, a first diode, and a second Polar body and a switch. The leakage inductance has a first end coupled to an input power source And a second end is coupled to the first end of one of the first coils of the primary side of the transformer. The second inductor has a first end coupled to the second end of the leakage inductance, and a second end coupled to the second end of the first coil of the primary side of the transformer. The first inductor has a second end coupled to the first end of one of the second coils of the secondary side of the transformer. The first diode has a positive electrode coupled to the first end of the first inductor, and a negative electrode coupled to an output terminal. The second diode has a positive pole coupled to the second end of the second coil of the secondary side of the transformer, and a negative pole coupled to the output end. The switch has a first end coupled to the second end of the first coil of the primary side of the transformer, and a second end coupled to a ground point.

In view of the above, a forward-return-type converter having a lossless vibration-damping circuit according to the present invention may have one or more of the following advantages:

(1) Streamlining the circuit architecture and reducing the complexity of the driver circuit.

(2) Use magnetic integration components to save components.

(3) Reduce the switching voltage stress.

(4) Reduce the loss caused by the inductance.

4, 51‧‧‧ forward-return converter

41, 511‧‧‧ transformer

524, 525‧‧‧ capacitor

43, 512‧‧‧ first inductance

441, 442, 516, 517, 521, 522, 523‧‧ ‧ diodes

45, 513‧‧ ‧ switch

5‧‧‧ Forward-return converter with lossless vibration-damping circuit

52‧‧‧Vibration feedback network

421, 514‧‧ ‧ leakage

422, 515‧‧‧ second inductance

53‧‧ ‧ Voltage divider

54‧‧‧Pulse width modulation control circuit

Figure 1 shows a conventional forward-return type converter; Figure 2 shows a conventional flyback converter with a lossless vibration-damping circuit; Figure 3 shows a conventional fly-back type with isolated coil feedback Converter; FIG. 4 shows a forward-return type converter in an embodiment of the present invention; and FIG. 5 shows a forward-return type conversion of a lossless vibration-damping circuit in another embodiment of the present invention And the sixth to seventh graphs show the forward-return-type converter with a lossless vibration-damping circuit in Figure 5. Signal waveform and efficiency map.

Please refer to FIG. 4, which is a forward-return type converter in an embodiment of the present invention. In the figure, the forward-return type converter 4 includes a transformer 41, a leakage inductance 421, a second inductance 422, a first inductance 43, a diode 441, 442, a switch 45, an output capacitance Co, and an output resistance Ro. The leakage inductance 421 has a first end coupled to an input power terminal Vin, and a second end coupled to a first end of the first winding N1 of the primary side of the transformer 41. The second inductor 422 has a first end coupled to the second end of the leakage inductance 421, and a second end coupled to the second end of the first coil N1 on the primary side of the transformer 41. The first inductor 43 has a second end coupled to one of the first ends of the second coil N2 on the secondary side of the transformer 41. The first inductor 43 can also be integrated in the transformer 41. The diode 441 has a positive pole coupled to one of the first ends of the first inductor 43 and a negative pole coupled to an output terminal Vout. The diode 442 has a positive electrode coupled to a second end of the second coil N2 on the secondary side of the transformer 41, and a negative electrode coupled to the output terminal Vout. The switch 45 has a first end coupled to the second end of the first coil N1 on the primary side of the transformer 41, and a second end coupled to a ground point. The output capacitor Co is coupled between the intermediate point of the second coil N2 on the secondary side of the transformer 41 and the output terminal Vout. The output resistor Ro is coupled between the intermediate point of the second coil N2 on the secondary side of the transformer 41 and the output terminal Vout. The first inductor 43, the leakage inductance 421, the second inductor 422, and the transformer 41 together form a magnetic integration component.

Please refer to FIG. 5, which is a forward-return type converter with a lossless vibration damping circuit according to another embodiment of the present invention. In the figure, the forward-return type converter 5 having a lossless vibration-damping circuit includes a forward-return type converter 51 and a vibration-recovery feedback network 52. The forward-return type converter 51 includes a transformer 511, a first inductor 512, and a switch 513. In the circuit of the primary side of the transformer 511, there is an input power terminal Vin and a switch 513, in the circuit of the secondary side of the transformer 511 has a first inductance 512; in addition, the first inductor 512 can also be integrated in the transformer 511. The vibration recovery feedback network 52 stores the energy of the leakage inductance 514, and uses the transformer 511 to return the energy to the input power terminal Vin to reduce the voltage stress Vds across the switch 513 and the switch 513 switching, and A feedback voltage Vfb is obtained on the secondary side of the transformer 511, and the switching of the switch 513 is determined by the feedback voltage Vfb.

The forward-return type converter 51 further includes a leakage inductance 514, a second inductance 515, and diodes 516, 517. The leakage inductance 514 has a first end coupled to the input power terminal Vin, and a second end coupled to the first end of the first winding N1 of the primary side of the transformer 511. The second inductor 515 has a first end coupled to the second end of the leakage inductance 514, and a second end coupled to the second end of the first coil N1 on the primary side of the transformer 511. The diode 516 has a positive pole coupled to one of the first ends of the first inductor 512 and a negative pole coupled to an output terminal Vout. The diode 517 has a positive pole coupled to the second end of the secondary side of the transformer 511 and a second coil N2, and a negative pole coupled to the output end Vout. The second end of one of the inductors 512 is coupled to one of the first ends of the second coil N2 on the secondary side of the transformer 511. The switch 513 has a first end coupled to the second end of the first coil N1 on the primary side of the transformer 511, and a second end coupled to a ground point. The first inductor 512, the second inductor 515 and the transformer 511 together form a magnetic integration component.

The vibration recovery feedback network 52 includes diodes 521, 522, 523, capacitors 524, 525, and a coil N3. The diode 521 has a negative pole coupled to the input power terminal Vin. The diode 522 has a cathode coupled to the anode of the diode 521. The diode 523 has a positive pole coupled to the anode of the diode 522, and a cathode coupled to the output terminal Vfb of the feedback voltage. The capacitor 524 is coupled to the anode of the diode 521 and the second end of the first coil N1 on the primary side of the transformer 511. The capacitor 525 is coupled between the cathode of the diode 523 and a grounding point. . The coil N3 is coupled to the first coil N1 on the secondary side of the transformer 511, and has a first end coupled to the anode of the diode 523 and a second end coupled to the ground point.

The forward-return type converter 5 having the lossless vibration-damping circuit in this embodiment may further include a voltage divider 53 and a pulse width modulation control circuit 54. The voltage divider 53 takes the feedback voltage Vfb and generates a divided voltage Vfb' of the feedback voltage Vfb. The pulse width modulation control circuit 54 uses the feedback voltage Vfb as the supply voltage, and outputs different pulse width modulation signals S according to the partial voltage Vfb' of the feedback voltage, so that the switch 513 switches according to the pulse width modulation signal S. .

The forward-return type converter 5 having the lossless vibration damping circuit in this embodiment may further include an output capacitor Co and an output resistor Ro. The output capacitor Co is coupled between the intermediate point of the second coil N2 on the secondary side of the transformer 511 and the output terminal Vout. The output resistor Ro is coupled between the intermediate point of the second coil N2 on the secondary side of the transformer 511 and the output terminal Vout.

The forward-return type converter 5 having a lossless vibration-damping circuit in Fig. 5 is described as follows. When the switch 513 is turned off (during t0~t1 in FIG. 6), the current of the inductor 512 is freewheeled and the energy is transmitted to the output via the diode 516, which is a characteristic of the forward converter. The energy of the magnetizing inductance 515 is transmitted to the secondary side coil N2 via the transformer 511 and transmitted to the output via the diode 517, which is a feature of the flyback converter.

When the switch 513 is turned off (during t0~t1 in FIG. 6), the energy of the inductor 514 is stored to the moderating capacitor 524 via the diode 521 to reduce the voltage stress Vds on the switch 513. In addition, it can be seen from Figure 7 that it can be effectively reduced by adding a lossless vibration-damping circuit. Switching voltage stress Vds.

When the switch 513 is turned on, the energy stored in the capacitor 524 is looped through the switch 513, the coil N3 and the diode 522, and the energy is transmitted to the input power terminal Vin through the transformer 511 to achieve the purpose of recovering the leakage 514 energy.

In summary, the present invention improves the conventional forward-return type converter by using the leakage inductance instead of the output inductor in the conventional converter, and also replaces the diode in the conventional converter to replace the diode in the conventional converter. The path. In addition to the advantages of a conventional forward-return converter, the improved circuit also saves an output inductor and an output diode component.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

5‧‧‧ Forward-return converter with lossless vibration-damping circuit

51‧‧‧ Forward-return converter

511‧‧‧Transformer

524, 525‧‧‧ capacitor

512‧‧‧first inductance

516, 517, 521, 522, 523‧‧ ‧ diodes

513‧‧‧ switch

52‧‧‧Vibration feedback network

514‧‧‧ Sense of leakage

515‧‧‧second inductance

53‧‧ ‧ Voltage divider

54‧‧‧Pulse width modulation control circuit

Claims (6)

A forward-return type converter with a lossless vibration damping circuit, comprising: a converter having a transformer, having a first inductance in a circuit on a secondary side of the transformer, and a circuit on a primary side of the transformer The utility model has an input power terminal and a switch; and a vibration recovery feedback network, which stores energy of a leakage inductance, and uses the transformer to return the energy to the input power terminal to reduce the two ends of the switch The voltage stress and the loss caused by the switching of the switch, and a feedback voltage is obtained on the secondary side of the transformer, and the switching of the switch is determined by the feedback voltage, wherein the leakage inductance has a first end coupled to the input The power terminal and the second end are coupled to the first end of the first coil of the primary side of the transformer; wherein the converter further includes: a second inductor having a first end coupled to the leakage inductance The second end and the second end are coupled to the second end of the first coil of the transformer; the first diode has a positive pole coupled to the first end of the first inductor And a negative pole coupled to an output; and a The second diode has a positive pole coupled to the second end of the second coil of the transformer and a second end coupled to the output end; wherein the vibration feedback feedback network comprises: a third The diode has a negative electrode coupled to the input power terminal; a fourth diode having a negative electrode coupled to the positive electrode of the third diode; and a fifth diode having a positive electrode coupled thereto a positive pole of the fourth diode, and a negative pole coupled to the output end of the feedback voltage; a first capacitor coupled to the anode of the third diode and the first coil of the primary side of the transformer The second end is coupled between the negative pole of the fifth diode and a grounding point; and a third coil is disposed on the secondary side of the transformer to be coupled to the first coil The first end is coupled to the anode of the fifth diode, and the second end is coupled to the ground. The forward-return type converter with a lossless vibration-damping circuit according to claim 1, wherein the first inductance, the leakage inductance, the second inductance, and the transformer system together form a magnetic integration component . The forward-return type converter with a lossless vibration-damping circuit according to claim 1, wherein the second end of the first inductor is coupled to the second coil of the secondary side of the transformer One of the first ends. The forward-return type converter with a lossless vibration-damping circuit according to claim 1, wherein the switch has a first end coupled to the second side of the first coil of the transformer The terminal and the second end are coupled to a grounding point. The forward-return type converter with a lossless vibration-damping circuit according to claim 1, further comprising: a voltage divider that obtains the feedback voltage and generates a partial pressure of the feedback voltage; And a pulse width modulation control circuit, wherein the feedback voltage is used as a supply voltage, and different pulse width modulation signals are output according to the partial pressure of the feedback voltage; wherein switching of the switch is performed according to the pulse width modulation The signal is switched. The forward-return type converter with a lossless vibration-damping circuit as described in claim 1, further comprising: an output capacitor coupled to an intermediate point of the second coil of the secondary side of the transformer And an output resistor coupled between the intermediate point of the second coil on the two sides of the transformer and the output end.