TWI723533B - Flyback power-converting device with zero-voltage switching and method for flyback converting power with zero-voltage switching - Google Patents

Abstract

A flyback power-converting device includes a transformer circuit, a clamp damping circuit, a first switch, a voltage-reducing circuit and a second switch. The clamp damping circuit and the first switch are coupled to the transformer circuit. The voltage-reducing circuit and the second switch are coupled in series between the clamp damping circuit and the transformer circuit. By switching the first switch, the transformer circuit converts an input power to generate a first converted voltage and to store an inductive energy in the clamp damping circuit. When the second switch is turned on, the clamp damping circuit releases the inductive energy to the transformer circuit via the voltage-reducing circuit, so that the transformer circuit generates a second converted voltage according to the inductive energy.

Description

Zero-voltage switching flyback power conversion device and zero-voltage switching flyback power conversion method

The invention relates to a power supply device, in particular to a flyback power conversion device and a flyback power conversion method.

With the development of science and technology, electronic devices occupy an extremely important position in our daily lives, and the power source that these electronic devices rely on is still a DC power supply. However, the mains electricity is AC power. Therefore, electronic devices are mostly coupled to an AC power source through an adapter, and the AC power source of the commercial power is converted into a DC power source by a power conversion device in the adapter to supply the power required for its operation.

In the application of power conversion devices, the Flyback Converter circuit architecture is the most common. The flyback power conversion device has the advantages of circuit isolation, simple structure and low cost. Flyback power conversion devices mainly include active clamp flyback (ACF) power conversion devices and passive clamp flyback power conversion devices (or called non-active clamp flyback power conversion devices). In order to miniaturize the adapter, an active clamp flyback power conversion device is an increasingly important power conversion technology.

Active clamp flyback power conversion device is a passive clamp flyback power conversion The Snubber diode of the converter is replaced with an auxiliary switch to reduce the switching loss and thereby improve the overall efficiency of the converter. In use, in order to have better efficiency, the active clamp flyback power conversion device will operate in Flyback Mode (that is, the auxiliary switch is not operating) under light load, and operate in active under heavy load. Active Mode (ie auxiliary switch action). However, when the auxiliary switch is operating, a surge current will be generated on the secondary side, which will damage the internal components.

In one embodiment, a flyback power conversion device includes: a transformer circuit, a clamp damping circuit, a first switch, a decompression circuit, and a second switch. The clamp damping circuit and the first switch are coupled to the transformer circuit. The decompression circuit and the second switch are connected in series between the clamp damping circuit and the transformer circuit. Wherein, through the switching of the first switch, the transformer circuit transforms an input power source to generate a first transformed voltage and causes the clamp damping circuit to store an induced energy. Moreover, when the second switch is turned on, the clamp damping circuit releases induced energy to the transformer circuit via the pressure reducing circuit, so that the transformer circuit generates a second converted voltage according to the induced energy.

In one embodiment, a flyback power conversion method includes: storing a converted energy in a primary winding of a transformer circuit, and transferring the converted energy stored in the primary winding to the secondary side of the transformer circuit The winding also enables the energy storage element to store an inductive energy, and releases the inductive energy stored by the energy storage element to the primary winding via a step-down element.

In summary, according to the flyback power conversion device and the flyback power conversion method of the present invention, it can avoid the surge on the secondary side when the clamp damping circuit is discharged through the auxiliary switch (ie, the second switch). Current, thereby reducing the impact on internal components to prolong the use time of the product, regenerating the induced energy to improve the efficiency of the product, and can choose a relatively low semiconductor rated voltage or The components of the current value to reduce the cost.

10: Flyback power conversion device

101: Input

102: output

110: Transformer circuit

120: clamp damping circuit

130: First switch

140: decompression circuit

150: second switch

160: The first rectifier filter circuit

20: The second rectifier filter circuit

30: Pulse width modulation controller

40: feedback controller

Vi: input power

Vo: output voltage

S1: The first switch signal

S2: The second switch signal

N1: Primary winding

N2: Secondary winding

LK: Leakage inductance

C1: Energy storage element

C2: output capacitor

R1: resistance

D1: Forward component

D2: Forward component

D3: Forward component

N3: step-down component

t11: the first time

t12: second time

t13: third time

t21: the first time

t22: second time

t23: third time

Vc1: voltage

Vlk: induced voltage

V1: induced voltage

V2: Conversion voltage

V3: induced voltage

Vac: AC power

AD: adapter

ED: Electronic device

S21~S23: steps

FIG. 1 is a functional block diagram of a flyback power conversion device according to an embodiment.

FIG. 2 is a functional block diagram of a flyback power conversion device according to another embodiment.

FIG. 3 is a schematic circuit diagram of an exemplary example of the flyback power conversion device of FIG. 1.

4 is a schematic circuit diagram of an exemplary example of the flyback power conversion device of FIG. 2.

FIG. 5 is a timing diagram of switching signals in the active mode of the flyback power conversion device of FIG. 3. FIG.

FIG. 6 is a flowchart of a flyback power conversion method according to an embodiment.

7 to 9 are schematic diagrams showing the operation of the flyback power conversion device of FIG. 3 in the active mode.

Fig. 10 is an equivalent circuit diagram of the flyback power conversion device of Fig. 9.

FIG. 11 is a timing diagram of switching signals in the flyback mode of the flyback power conversion device of FIG. 3.

FIG. 12 is a schematic diagram of the operation of a step in the flyback mode of the flyback power conversion device of FIG. 3.

Fig. 13 is a functional block diagram of an adapter according to an embodiment.

1, a flyback power conversion device 10 includes: a transformer circuit 110, a clamp damping circuit 120, a first switch 130, a decompression circuit 140 and a second switch 150.

The clamp damping circuit 120 is coupled to the primary side of the transformer circuit 110. Here, the clamp damping circuit 120 is connected in parallel with the primary side of the transformer circuit 110, that is, the clamp damping circuit 120 is coupled to the transformer circuit 110. Between the first end and the second end of the primary side of the voltage circuit 110. In addition, the first terminal of the primary side of the transformer circuit 110 is further coupled to the input terminal 101.

The first switch 130 is coupled between the second end of the primary side of the transformer circuit 110 and the ground. Here, through the switching of the first switch 130, the transformer circuit 110 transforms an input power Vi to generate a transformed voltage (hereinafter referred to as the first transformed voltage) and causes the clamp damping circuit 120 to store an induced energy.

A release path is further coupled between the clamp damping circuit 120 and the second end of the primary side of the transformer circuit 110. The decompression circuit 140 and the second switch 150 are arranged on the energy release path. In other words, the pressure reducing circuit 140 is coupled between the clamp damping circuit 120 and the second end of the transformer circuit 110 on the primary side. The second switch 150 and the decompression circuit 140 are connected in series between the clamp damping circuit 120 and the second end of the primary side of the transformer circuit 110. Here, the second switch 150 is used to turn on or turn off the energy release path. Wherein, when the second switch 150 is turned on, the clamp damping circuit 120 will release the induced energy to the transformer circuit 110 via the decompression circuit 140, so that the transformer circuit 110 generates another converted voltage according to the induced energy (hereinafter referred to as the second conversion Voltage). In an exemplary embodiment, the decompression circuit 140 is coupled between the clamp damping circuit 120 and the first end of the second switch 150, and the second end of the second switch 150 is coupled to the primary side of the transformer circuit 110 The second end, as shown in Figure 1. In another exemplary embodiment, the clamp damping circuit 120 is coupled to the first terminal of the second switch 150, and the pressure reducing circuit 140 is coupled to the second terminal of the second switch 150 and the first terminal of the primary side of the transformer circuit 110. Between the two ends, as shown in Figure 2. In some embodiments, the second conversion voltage is less than the first conversion voltage.

In some embodiments, the flyback power conversion device 10 further includes: a rectifier and filter circuit (hereinafter referred to as the first rectifier and filter circuit 160). The first rectifying and filtering circuit 160 is coupled between the secondary side of the transformer circuit 110 and the output terminal 102. In the transformer circuit 110 to generate the first conversion power When the voltage is low, the first rectification filter circuit 160 receives the first converted voltage and generates an output voltage Vo at the output terminal 102 according to the first converted voltage. When the transformer circuit 110 generates the second converted voltage, the first rectifier filter circuit 160 cuts off the output path because the second converted voltage is less than the output voltage Vo.

In some embodiments, referring to FIG. 3 or FIG. 4, the transformer circuit 110 includes a primary winding N1 and a secondary winding N2. The primary winding N1 and the secondary winding N2 are inductively coupled to each other.

The first end of the clamp damping circuit 120 is coupled to the first end of the primary winding N1. The second end of the clamp damping circuit 120 is coupled to the pressure reducing circuit 140 (as shown in FIG. 3) or to the second switch 150 (as shown in FIG. 4). The third terminal of the clamp damping circuit 120 is coupled to the output terminal 102. In some embodiments, the clamp damping circuit 120 includes an energy storage element C1 and a forward conducting element D1. One end of the energy storage element C1 (ie, the first end of the clamp damping circuit 120) is coupled to the first end of the primary winding N1 and the input terminal 101. The other end of the energy storage element C1 (ie, the second end of the clamp damping circuit 120) is coupled to the decompression circuit 140 (as shown in FIG. 3) or to the first end of the second switch 150 (as shown in FIG. 4) ). Here, the other end of the energy storage element C1 is further coupled to the cathode of the forward conducting element D1. The anode of the forward conducting element D1 (that is, the third end of the clamp damping circuit 120) is coupled to the second end of the primary winding N1. In some embodiments, the clamp damping circuit 120 may further include a resistor R1, and the resistor R1 is connected in parallel with the energy storage element C1. Wherein, the energy storage element C1 can be a capacitor.

In some embodiments, the first terminal of the first switch 130 is coupled to the second terminal of the primary winding N1. The second terminal of the first switch 130 is coupled to ground. The control terminal of the first switch 130 is coupled to a Pulse Width Modulation (PWM) controller (not shown). Wherein, the first switch 130 may be an N-type Metal-Oxide-Semiconductor FET (NMOSFET); here, the first The first terminal, the second terminal and the control terminal of the switch 130 are drain, source and gate respectively.

In some embodiments, the decompression circuit 140 includes a decompression element N3. In an exemplary embodiment, the step-down element N3 is coupled between the other end of the energy storage element C1 and the first end of the second switch 150, as shown in FIG. 3. In another exemplary embodiment, the step-down element N3 is coupled between the second end of the second switch 150 and the second end of the primary winding N1, as shown in FIG. 4. In some embodiments, the decompression circuit 140 may further include a forward conducting element D2. The forward conducting element D2 is coupled to any position of the energy release path in such a manner that the direction of the current flowing from the energy storage element C1 to the second end of the primary winding N1 is forward. For example, the step-down element N3, the forward conducting element D2 and the second switch 150 are connected in series between the other end of the energy storage element C1 and the second end of the primary winding N1, as shown in FIG. 3. Alternatively, the second switch 150, the forward conducting element D2, and the step-down element N3 are connected in series between the other end of the energy storage element C1 and the second end of the primary winding N1, as shown in FIG. 4. Alternatively, the forward conducting element D2, the second switch 150, and the step-down element N3 are sequentially connected in series between the other end of the energy storage element C1 and the second end of the primary winding N1 (not shown). Alternatively, the second switch 150, the step-down element N3 and the forward conducting element D2 are connected in series between the second end of the primary winding N1 and the other end of the energy storage element C1 (not shown). Alternatively, the step-down element N3, the second switch 150 and the forward conducting element D2 are connected in series between the other end of the energy storage element C1 and the second end of the primary winding N1 (not shown). Alternatively, the forward conducting element D2, the voltage reducing element N3, and the second switch 150 are connected in series between the other end of the energy storage element C1 and the second end of the primary winding N1 (not shown). Here, the forward conducting element D2 restricts the output current of the transformer circuit 110 from flowing through the parasitic diode of the second switch 150. Among them, the step-down element N3 can be an auxiliary winding. The second switch 150 may be an N-type Metal-Oxide-Semiconductor FET (N-type Metal-Oxide-Semiconductor FET, NMOSFET); here, the first terminal, the second terminal and the control terminal of the first switch 130 are drains respectively. Pole, source and gate. In some embodiments, the primary winding N1 and the auxiliary winding (ie, the voltage reducing element N3) can be wound on the same bobbin. In other words, the primary winding N1 and the auxiliary winding have the same polarity.

The first rectification filter circuit 160 includes a primary rectification circuit. Wherein, the secondary rectifier circuit may include a forward conducting element D3. The anode of the forward conducting element D3 is coupled to the first end of the secondary winding N2, and the cathode of the forward conducting element D3 is coupled to the output terminal 102. Here, when the transformer circuit 110 generates the second conversion voltage, the forward conducting element D3 is turned off because the second conversion voltage is less than the output voltage Vo. In some embodiments, the first rectifying and filtering circuit 160 may further include a primary filtering circuit. The secondary filter circuit may include an output capacitor C2, and the output capacitor C2 is coupled to the output terminal 102.

In the Active Mode operation, taking the circuit structure shown in FIG. 3 as an example, the control terminal of the first switch 130 receives a switch signal (hereinafter referred to as the first switch signal S1), and the control of the second switch 150 The terminal receives another switch signal (hereinafter referred to as the second switch signal S2). The timing sequence of the first switch signal S1 and the second switch signal S2 is shown in FIG. 5.

3, 5 and 6, during the first time t11, the first switch 130 is turned on, and the second switch 150 is turned off; at this time, the primary winding N1 receives the input power Vi to store a converted energy in it (step S21), as shown in Figure 7. In Fig. 7, the arrow dashed line indicates the direction of current.

During the second time t12, the first switch 130 is turned off, and the second switch 150 is turned off; at this time, the converted energy stored in the primary winding N1 is transferred to the secondary winding N2, that is, the transformer circuit 110 passes through the primary The electromagnetic coupling of the side winding N1 and the secondary side winding N2 converts the input power Vi into a converted voltage, and charges the energy storage element C1 through the forward conducting element D1 to make The energy storage element C1 stores an induced energy (step S22), as shown in FIG. 8. Here, the voltage (Vc1) on the energy storage element C1 is NVo+Vlk. Among them, N is the turns ratio of the primary winding N1 and the secondary winding N2, and Vlk is the induced voltage of the leakage inductance LK generated by the primary winding N1. In Fig. 8, the arrow dashed line indicates the direction of current.

During the third time t13, the first switch 130 is turned off, and the second switch 150 is turned on; at this time, the energy storage element C1 releases the stored inductive energy to the primary winding N1 via the step-down element N3, and connects to the primary winding N1 via the primary winding N1. The electromagnetic coupling of the secondary winding N2 is transferred to the secondary winding N2 (step S23), as shown in FIG. 9. Here, the equivalent circuit of the flyback power conversion device 10 is shown in FIG. 10. After the pressure is reduced by the step-down element N3, the conversion voltage (V2) generated by the secondary winding N2 is less than the output voltage Vo, so the forward conducting element D3 is turned off. In Figs. 9 and 10, the arrow dashed line indicates the direction of current. Among them, V1 is the induced voltage of the primary winding N1.

For example, suppose that the output voltage Vo is fixed at 20V (volts), the number of turns of the primary winding N1 is 6, the number of turns of the secondary winding N2 is 1, and the number of turns of the auxiliary winding (ie, the step-down element N3) is 1. , And the induced voltage Vlk of the leakage inductance LK is 6V.

During the second time t12, the voltage Vc1 on the energy storage element C1 is 126V, as shown in Equation 1.

Vc1=NVo+Vlk=(N1/N2)*Vo+Vlk=(6/1)*20V+6V=126V Equation 1

During the third time t13, the energy storage element C1 releases stored energy. At this time, the converted voltage V2 reflected to the secondary winding N2 is 17.66V, as shown in Equation 2. Among them, V3 is the induced voltage of the auxiliary winding (ie, the step-down element N3).

V2=(Vc1-V3)*(N2/N1)=(126-20)(1/6)=126V formula 2

At this time, because the output voltage Vo is 20V and the conversion voltage V2 of the secondary winding N2 is 17.66V, the forward conducting element D3 on the secondary side of the transformer circuit 110 cannot be turned on (ie, cut off), so the transformer can be avoided The secondary side of the circuit 110 generates a surge current, and the energy released by the energy storage element C1 will eventually flow back to itself.

In some embodiments, the flyback power conversion device 10 has an operation mode of a flyback mode.

In the operation of the flyback mode, taking the circuit structure shown in FIG. 3 as an example, the control terminal of the first switch 130 receives the first switch signal S1, and the control terminal of the second switch 150 receives the second switch signal S2. The timing sequence of the first switch signal S1 and the second switch signal S2 is shown in FIG. 11. In this mode, the second switch signal S2 is at the off level, that is, the second switch 150 maintains the off state. The first switch signal S1 alternately switches between the on level and the off level.

3 and 1, during the first time t21, the first switch 130 is turned on, and the second switch 150 is turned off; at this time, the primary winding N1 receives the input power Vi to store a converted energy therein, as shown in FIG. Show.

During the second time t22, the first switch 130 is turned off, and the second switch 150 remains turned off; at this time, the converted energy stored in the primary winding N1 is transferred to the secondary winding N2, that is, the transformer circuit 110 uses The electromagnetic coupling between the primary winding N1 and the secondary winding N2 converts the input power Vi into a converted voltage, and charges the energy storage element C1 through the forward conducting element D1 so that the energy storage element C1 stores an induced energy, as shown in Figure 8. Shown.

During the third time t23, the first switch 130 is turned on again, while the second switch 150 remains turned off; at this time, the input energy is stored in the primary winding N1 again, and the inductive energy originally stored on the energy storage element C1 pair Resistor R1 releases energy, as shown in Figure 12.

In some embodiments, the aforementioned forward conducting elements D1 to D3 may be diodes.

In some embodiments, referring to FIG. 13, the flyback power conversion device 10 of any of the foregoing embodiments is applicable to an adapter AD. The electronic device ED uses the adapter AD to convert the AC power Vac of the commercial power into a DC power (that is, the output voltage Vo) to supply the power required for its operation.

The adapter AD includes the flyback power conversion device 10 of any of the foregoing embodiments, another rectification filter circuit (hereinafter referred to as the second rectification filter circuit 20), a pulse width modulation controller 30, and a feedback controller 40. The second rectifying and filtering circuit 20 is coupled between the AC power source Vac and the input terminal 101 of the flyback power conversion device 10. The pulse width modulation controller 30 is coupled to the control terminal of the flyback power conversion device 10 (ie, the control terminal of the first switch 130 and the control terminal of the second switch 150). The feedback controller 40 is coupled to the output terminal 102 of the flyback power conversion device 10 and the feedback terminal of the pulse width modulation controller 30.

The feedback controller 40 converts the output voltage Vo into a feedback voltage. The pulse width modulation controller 30 generates the first switching signal S1 and the second switching signal S2 according to the feedback voltage. The second rectifying and filtering circuit 20 receives the AC power Vac and rectifies and filters it to generate the input power Vi to the flyback power conversion device 10. The flyback power conversion device 10 converts the input power Vi into the output voltage Vo based on the control of the first switch signal S1 and the second switch signal S2 and provides the output voltage Vo to the electronic device ED. The pulse width modulation controller 30 may include a mode control circuit and a pulse width modulation generating circuit. The pulse width modulation generating circuit generates a pulse width modulation signal to the mode control circuit according to the feedback voltage. The mode control circuit generates the first switching signal S1 and the second switching signal S2 according to the feedback voltage and the pulse width modulation signal, so as to control the operation mode of the flyback power conversion device 10. In some embodiments, the pulse width modulation controller 30 can be made of a single chip (Integrated Circuit, IC) implementation.

In summary, according to the flyback power conversion device and flyback power conversion method of the present invention, it can avoid the secondary side generation when the clamp damping circuit 120 is discharged through the auxiliary switch (ie, the second switch 150). Surge current reduces the impact on internal components to prolong the use time of the product, restores the induced energy to improve product efficiency, and can select components with relatively low semiconductor rated voltage or current to reduce costs.

10: Flyback power conversion device

110: Transformer circuit

120: clamp damping circuit

130: First switch

140: decompression circuit

150: second switch

160: The first rectifier filter circuit

20: The second rectifier filter circuit

30: Pulse width modulation controller

40: feedback controller

Vi: input power

Vo: output voltage

S1: The first switch signal

S2: The second switch signal

Vac: AC power

AD: adapter

ED: Electronic device

Claims (5)

A flyback power conversion device includes: a transformer circuit; a clamp damping circuit coupled to the transformer circuit; a first switch coupled to the transformer circuit, wherein the switching of the first switch , The transformer circuit converts an input power source to generate a first converted voltage and causes the clamp damping circuit to store an induced energy; a pressure reducing circuit is coupled between the clamp damping circuit and the transformer circuit And a second switch connected in series with the decompression circuit between the clamp damping circuit and the transformer circuit, wherein when the second switch is turned on, the clamp damping circuit is paired via the decompression circuit The transformer circuit releases the induced energy, so that the transformer circuit generates a second converted voltage according to the induced energy; wherein the pressure reducing circuit includes: an auxiliary winding, wherein when the second switch is turned on, the clamp dampens vibration The circuit releases the induced energy to the transformer circuit through the auxiliary winding; and a forward conducting element for limiting the current output by the transformer circuit to flow through the parasitic diode of the second switch. The flyback power conversion device according to claim 1, wherein the transformer circuit includes a primary winding and a secondary winding inductively coupled with the primary winding, and the first end of the clamp damping circuit Is coupled to the first end of the primary winding, the first switch is coupled between the second end of the primary winding and ground, and the decompression circuit is coupled to the second end of the clamp damping circuit and the The first terminal of the second switch and the second terminal of the second switch are coupled to the second terminal of the primary winding. The flyback power conversion device according to claim 1, wherein the transformer circuit includes a primary winding and a secondary winding inductively coupled with the primary winding, and the first end of the clamp damping circuit Coupled to the first end of the primary winding, the first switch is coupled between the second end of the primary winding and ground, and the second end of the clamp damping circuit is coupled to the first end of the second switch , And the decompression circuit is coupled between the second end of the primary winding and the second end of the second switch. The flyback power conversion device according to claim 1, wherein the clamp damping circuit includes: an energy storage element, one end of the energy storage element is coupled to the first end of the transformer circuit; and another forward direction The conduction element is coupled between the second end of the transformer circuit and the other end of the energy storage element, wherein when the first switch is turned off, the other forward conduction element is turned on, and the transformer circuit passes through the other end A forward conducting element charges the energy storage element so that the energy storage element stores the induced energy. A flyback power conversion method includes: when a first switch is turned on and a second switch is turned off, storing a conversion energy in a primary winding of a transformer circuit; turning off the first switch and turning off the During the second switch, the converted energy stored in the primary winding is transferred to a secondary winding of the transformer circuit and the energy storage element stores an induced energy; and When the first switch is turned off and the second switch is turned on, the induced energy stored in the energy storage element is released to the primary winding via an auxiliary winding, and a forward conducting element is used to limit the current flow output by the primary winding Through the parasitic diode of the second switch.

Images