Flyback double-tube voltage conversion circuit

Abstract

The invention discloses a flyback double-tube voltage conversion circuit, which comprises a primary circuit, a secondary circuit, an auxiliary circuit and a double-tube flyback transformer, and is characterized in that the double-tube flyback transformer comprises a double-tube flyback circuit, a primary winding and a secondary winding; by arranging the primary side circuit, the secondary side circuit, the auxiliary circuit and the double-tube flyback transformer, the auxiliary circuit can increase the potential of the first end of the primary side winding and reduce the potential of the second end of the primary side winding before the primary side winding is charged, so that the voltage between the first electrode and the second electrode of a power switch tube in the primary side circuit can be adjusted; therefore, the voltage between the first electrode and the second electrode is close to 0 before the power switch tube is conducted, thereby facilitating the realization of soft switching. Meanwhile, the double-transistor flyback circuit in the double-transistor flyback transformer has the advantages of being high in conversion efficiency, low in requirement for voltage resistance of a power switch tube and the like, and therefore the double-transistor flyback transformer can be well suitable for application scenes with high input voltage.

Description

Technical Field

[0001] The invention relates to the technical field of converters, in particular to a flyback dual-tube voltage conversion circuit. Background Art

[0002] Power electronic equipment is closely related to people's work and life. Power supply is an indispensable source of power for all electronic equipment, and power conversion equipment is also an important component of electronic equipment. Among the power supplies, the flyback switching power supply is the most commonly used one, which has a simple topology, low manufacturing cost, a wide voltage rise and fall range, is suitable for multiple outputs, and has stable and reliable output power supply. Among them, the dual-tube flyback switching power supply has the advantages of low voltage stress requirements for the switch tube, good input and output electrical isolation, high conversion efficiency, and more stable and reliable output voltage compared to the single-tube switching power supply.

[0003] However, the existing flyback dual-tube voltage conversion circuit has disadvantages such as low conversion efficiency and high requirements on the voltage resistance performance of the power switch tube, which reduces the convenience of using the flyback dual-tube voltage conversion circuit. Therefore, we propose a flyback dual-tube voltage conversion circuit to solve the above-mentioned problems. Summary of the invention

[0004] The object of the present invention is to provide a flyback dual-transistor voltage conversion circuit to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a flyback dual-tube voltage conversion circuit, comprising a primary circuit, a secondary circuit, an auxiliary circuit and a dual-tube flyback transformer, wherein the primary circuit, the secondary circuit, the auxiliary circuit and the dual-tube flyback transformer are coupled to each other, the dual-tube flyback transformer comprises a dual-tube flyback circuit, a primary winding and a secondary winding, the dual-tube flyback circuit comprises a first switch tube, a second switch tube, a switch tube protection circuit, a resistor, a voltage regulator diode, a control circuit, an absorption circuit, an output rectification and filtering circuit; the first side of the primary circuit is connected to the primary winding, and the second side of the primary circuit comprises a first end, a second end and a position At the third end between the first end and the second end, a DC voltage is provided between the first end and the second end of the primary circuit, and the potential difference between the first end and the third end of the primary circuit is equal to the potential difference between the second end and the third end of the primary circuit; the secondary circuit is connected to the secondary winding, and the secondary winding is used to receive the electric energy released by the primary winding when the primary winding is discharged; the auxiliary circuit includes an auxiliary winding, an auxiliary capacitor and an auxiliary switch tube, one end of the auxiliary capacitor is connected to the first end of the auxiliary winding, the other end of the auxiliary capacitor is connected to the second electrode of the auxiliary switch tube, and the first electrode of the auxiliary switch tube is connected to the second end of the auxiliary winding.

[0006] As a further solution of the present invention: the positive end of the input end of the dual-tube flyback circuit is connected to the same-name end of the primary coil winding of the dual-tube flyback transformer, the non-same-name end of the primary coil winding of the dual-tube flyback transformer is connected to the drain of the second switch tube, the source of the second switch tube is connected to the drain of the first switch tube, and the source of the first switch tube is connected to the negative end of the input end of the dual-tube flyback circuit.

[0007] As a further solution of the present invention: the dual-tube flyback transformer also includes a clamping protection circuit, and the clamping protection circuit includes a first diode and a second diode, the cathode of the first diode is connected to the first end of the primary circuit, the anode of the first diode is connected to the second end of the primary winding, the cathode of the second diode is connected to the first end of the primary winding, and the anode of the second diode is connected to the second end of the primary circuit.

[0008] As a further solution of the present invention: it also includes a switch tube protection circuit, which is composed of a resistor and a capacitor connected in series, and the two ends of the series connection of the resistor and the capacitor are respectively connected to the source and the drain of the second switch tube.

[0009] As a further solution of the present invention: the dual-tube flyback circuit also includes an anti-backflow unit, and the anti-backflow unit includes a first anti-backflow diode and a second anti-backflow diode; the cathode of the first anti-backflow diode is connected to the first end of the primary circuit, and the anode of the first anti-backflow diode is used to be connected to the positive end of the DC bus; the anode of the second anti-backflow diode is connected to the second end of the primary circuit, and the cathode of the second anti-backflow diode is used to be connected to the negative end of the DC bus.

[0010] As a further solution of the present invention: the control circuit is used to control the auxiliary circuit to charge the auxiliary winding before controlling the primary circuit to charge the primary winding, so that the auxiliary winding stores electrical energy; control the auxiliary circuit to stop charging the auxiliary winding and make the auxiliary circuit release the stored electrical energy to the primary winding, so that the potential of the first end of the primary winding increases and the potential of the second end of the primary winding decreases, wherein the potential of the second end of the primary winding is higher than the potential of the first end of the primary winding during the charging of the auxiliary winding.

[0011] As a further solution of the present invention: the primary circuit also includes a third opening tube, a fourth switch tube, a third diode, a fourth diode and an input capacitor.

[0012] As a further solution of the present invention: the first electrode of the third switch tube is respectively connected to one end of the input capacitor and the cathode of the third diode, the first electrode of the third switch tube is used to receive the input voltage, the second electrode of the third switch tube is respectively connected to the cathode of the fourth diode and the first end of the primary winding, the second end of the primary winding is respectively connected to the anode of the third diode and the first electrode of the fourth switch tube, the second electrode of the fourth switch tube is connected to the anode of the fourth diode, and the second electrode of the fourth switch tube is connected to the other end of the input capacitor with the same potential.

[0013] As a further solution of the present invention: the primary winding includes a center tap, and a first primary winding and a second primary winding respectively connected to the center tap.

[0014] As a further solution of the present invention: the auxiliary switch tube is used to enable the auxiliary capacitor to charge the auxiliary winding after being turned on, and to stop the auxiliary capacitor from charging the auxiliary winding after being turned off, and to discharge the auxiliary winding to the primary winding.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The flyback dual-tube voltage conversion circuit is provided with a primary circuit, a secondary circuit, an auxiliary circuit and a dual-tube flyback transformer. The auxiliary circuit can increase the potential of the first end of the primary winding and reduce the potential of the second end of the primary winding before the primary winding is charged, thereby adjusting the voltage between the first electrode and the second electrode of the power switch tube in the primary circuit, so that before the power switch tube is turned on, the voltage between the first electrode and the second electrode approaches 0, which is conducive to realizing soft switching; at the same time, the dual-tube flyback circuit in the dual-tube flyback transformer has the advantages of high conversion efficiency and low voltage resistance performance requirements for the power switch tube, so it can be better applicable to application scenarios with higher input voltage.

[0017] The flyback dual-tube voltage conversion circuit can provide a clamping protection circuit so that leakage inductance energy can be fed back to the input capacitor through the clamping protection circuit, and no additional RCD absorption circuit is required, thereby avoiding RCD loss and reducing circuit cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the flyback dual-tube voltage conversion circuit of the present invention. DETAILED DESCRIPTION

[0019] In one embodiment, Figure 1As shown, a flyback double-tube voltage conversion circuit includes a primary circuit, a secondary circuit, an auxiliary circuit and a double-tube flyback transformer, wherein the primary circuit, the secondary circuit, the auxiliary circuit and the double-tube flyback transformer are coupled to each other, the double-tube flyback transformer includes a double-tube flyback circuit, a primary winding and a secondary winding, the double-tube flyback circuit includes a first switch tube, a second switch tube, a switch tube protection circuit, a resistor, a voltage regulator diode, a control circuit, an absorption circuit, an output rectification and filtering circuit; the first side of the primary circuit is connected to the primary winding, and the second side of the primary circuit includes a first end, a second end and a circuit located between the first end and the second end. A third end between the first and second ends of the primary circuit provides a DC voltage, and the potential difference between the first and third ends of the primary circuit is equal to the potential difference between the second and third ends of the primary circuit; the secondary circuit is connected to the secondary winding, and the secondary winding is used to receive the electric energy released by the primary winding when the primary winding is discharged; the auxiliary circuit includes an auxiliary winding, an auxiliary capacitor and an auxiliary switch tube, one end of the auxiliary capacitor is connected to the first end of the auxiliary winding, the other end of the auxiliary capacitor is connected to the second electrode of the auxiliary switch tube, and the first electrode of the auxiliary switch tube is connected to the second end of the auxiliary winding;

[0020] The positive end of the input end of the double-tube flyback circuit is connected to the same-name end of the primary coil winding of the double-tube flyback transformer, the non-same-name end of the primary coil winding of the double-tube flyback transformer is connected to the drain of the second switch tube, the source of the second switch tube is connected to the drain of the first switch tube, and the source of the first switch tube is connected to the negative end of the input end of the double-tube flyback circuit;

[0021] The double-tube flyback transformer also includes a clamping protection circuit, which includes a first diode and a second diode, wherein the cathode of the first diode is connected to the first end of the primary circuit, the anode of the first diode is connected to the second end of the primary winding, the cathode of the second diode is connected to the first end of the primary winding, and the anode of the second diode is connected to the second end of the primary circuit;

[0022] The clamping protection circuit can feed back the leakage inductance energy to the input side without the need for an absorption circuit composed of an RCD, thereby avoiding the loss of the RCD absorption circuit. Therefore, the double-tube flyback transformer provided in the embodiment of the present application can adapt to high-power applications. By setting up a clamping protection circuit, the leakage inductance energy can be fed back to the input capacitor through the clamping protection circuit, without the need to additionally set up an RCD absorption circuit, thereby avoiding the loss of the RCD and reducing the circuit cost.

[0023] It also includes a switch tube protection circuit, which is composed of a resistor and a capacitor connected in series, and the two ends of the resistor and capacitor connected in series are respectively connected to the source and drain of the second switch tube;

[0024] The double-tube flyback circuit also includes an anti-backflow unit, which includes a first anti-backflow diode and a second anti-backflow diode; the cathode of the first anti-backflow diode is connected to the first end of the primary circuit, and the anode of the first anti-backflow diode is used to connect to the positive end of the DC bus; the anode of the second anti-backflow diode is connected to the second end of the primary circuit, and the cathode of the second anti-backflow diode is used to connect to the negative end of the DC bus; used to prevent excessive backflow current from being generated when the upper half bus voltage is unequal to the lower half bus voltage;

[0025] Specifically, the anti-backflow unit includes a first anti-backflow diode and a second anti-backflow diode. The anode of the first anti-backflow diode is connected to the positive pole of the DC bus, and the cathode of the first anti-backflow diode is connected to the first end of the primary circuit. The anode of the second anti-backflow diode is connected to the second end of the primary circuit, and the cathode of the second anti-backflow diode is connected to the negative pole of the DC bus; the first end of the primary circuit is connected to the positive end of the DC bus through the first anti-backflow diode, the second end of the primary circuit is connected to the negative end of the DC bus through the second anti-backflow diode, and the third end of the primary circuit is connected to the bus midpoint of the DC bus in the power system, and the active voltage equalization of the bus capacitor is realized by controlling the first switch tube and the second switch tube in the double-tube flyback topology circuit to switch together.

[0026] The control circuit is used to control the auxiliary circuit to charge the auxiliary winding before controlling the primary circuit to charge the primary winding, so that the auxiliary winding stores electric energy; control the auxiliary circuit to stop charging the auxiliary winding and make the auxiliary circuit release the stored electric energy to the primary winding, so that the potential of the first end of the primary winding increases and the potential of the second end of the primary winding decreases, wherein the potential of the second end of the primary winding is higher than the potential of the first end of the primary winding during the charging of the auxiliary winding;

[0027] The primary circuit also includes a third light-opening tube, a fourth switch tube, a third diode, a fourth diode and an input capacitor;

[0028] The first electrode of the third switch tube is respectively connected to one end of the input capacitor and the cathode of the third diode, the first electrode of the third switch tube is used to receive the input voltage, the second electrode of the third switch tube is respectively connected to the cathode of the fourth diode and the first end of the primary winding, the second end of the primary winding is respectively connected to the anode of the third diode and the first electrode of the fourth switch tube, the second electrode of the fourth switch tube is connected to the anode of the fourth diode, and the second electrode of the fourth switch tube is connected to the other end of the input capacitor with equal potential;

[0029] The primary winding includes a center tap, and a first primary winding and a second primary winding respectively connected to the center tap;

[0030] The auxiliary switch tube is used to enable the auxiliary capacitor to charge the auxiliary winding after being turned on, and to stop the auxiliary capacitor from charging the auxiliary winding after being turned off, and to discharge the auxiliary winding to the primary winding;

[0031] The present invention, by setting a primary circuit, a secondary circuit, an auxiliary circuit and a double-tube flyback transformer, the auxiliary circuit can increase the potential of the first end of the primary winding and reduce the potential of the second end of the primary winding before the primary winding is charged, so that the voltage between the first electrode and the second electrode of the power switch tube in the primary circuit can be adjusted, so that before the power switch tube is turned on, the voltage between the first electrode and the second electrode approaches 0, which is conducive to realizing soft switching; at the same time, the double-tube flyback circuit in the double-tube flyback transformer has the advantages of high conversion efficiency and low voltage resistance performance requirements of the power switch tube, so it can be better applicable to application scenarios with higher input voltage.

[0032] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A flyback dual-tube voltage conversion circuit, characterized in that: The invention comprises a primary circuit, a secondary circuit, an auxiliary circuit and a double-tube flyback transformer, wherein the primary circuit, the secondary circuit, the auxiliary circuit and the double-tube flyback transformer are coupled to each other, the double-tube flyback transformer comprises a double-tube flyback circuit, a primary winding and a secondary winding, the double-tube flyback circuit comprises a first switch tube, a second switch tube, a switch tube protection circuit, a resistor, a voltage regulator diode, a control circuit, an absorption circuit, an output rectification and filtering circuit; the first side of the primary circuit is connected to the primary winding, the second side of the primary circuit comprises a first end, a second end and a third end located between the first end and the second end, the A DC voltage is provided between the first end and the second end of the primary circuit, and the potential difference between the first end and the third end of the primary circuit is equal to the potential difference between the second end and the third end of the primary circuit; the secondary circuit is connected to the secondary winding, and the secondary winding is used to receive the electric energy released by the primary winding when the primary winding is discharged; the auxiliary circuit includes an auxiliary winding, an auxiliary capacitor and an auxiliary switch tube, one end of the auxiliary capacitor is connected to the first end of the auxiliary winding, the other end of the auxiliary capacitor is connected to the second electrode of the auxiliary switch tube, and the first electrode of the auxiliary switch tube is connected to the second end of the auxiliary winding.

2. The flyback dual-transistor voltage conversion circuit according to claim 1, characterized in that: The positive end of the input end of the double-tube flyback circuit is connected to the same-name end of the primary coil winding of the double-tube flyback transformer, the non-same-name end of the primary coil winding of the double-tube flyback transformer is connected to the drain of the second switch tube, the source of the second switch tube is connected to the drain of the first switch tube, and the source of the first switch tube is connected to the negative end of the input end of the double-tube flyback circuit.

3. The flyback dual-transistor voltage conversion circuit according to claim 1, characterized in that: The double-tube flyback transformer also includes a clamping protection circuit, which includes a first diode and a second diode, wherein the cathode of the first diode is connected to the first end of the primary circuit, the anode of the first diode is connected to the second end of the primary winding, the cathode of the second diode is connected to the first end of the primary winding, and the anode of the second diode is connected to the second end of the primary circuit.

4. The flyback dual-transistor voltage conversion circuit according to claim 1, characterized in that: It also includes a switch tube protection circuit, which is composed of a resistor and a capacitor connected in series, and the two ends of the resistor and capacitor are respectively connected to the source and drain of the second switch tube.

5. The flyback dual-transistor voltage conversion circuit according to claim 1, characterized in that: The dual-tube flyback circuit also includes an anti-backflow unit, which includes a first anti-backflow diode and a second anti-backflow diode; the cathode of the first anti-backflow diode is connected to the first end of the primary circuit, and the anode of the first anti-backflow diode is used to be connected to the positive end of the DC bus; the anode of the second anti-backflow diode is connected to the second end of the primary circuit, and the cathode of the second anti-backflow diode is used to be connected to the negative end of the DC bus.

6. The flyback dual-transistor voltage conversion circuit according to claim 1, characterized in that: The control circuit is used to control the auxiliary circuit to charge the auxiliary winding before controlling the primary circuit to charge the primary winding, so that the auxiliary winding stores electrical energy; control the auxiliary circuit to stop charging the auxiliary winding and make the auxiliary circuit release the stored electrical energy to the primary winding, so that the potential of the first end of the primary winding increases and the potential of the second end of the primary winding decreases, wherein the potential of the second end of the primary winding is higher than the potential of the first end of the primary winding during the charging of the auxiliary winding.

7. The flyback dual-transistor voltage conversion circuit according to claim 1, characterized in that: The primary circuit also includes a third light-opening tube, a fourth switch tube, a third diode, a fourth diode and an input capacitor.

8. The flyback dual-transistor voltage conversion circuit according to claim 7, characterized in that: The first electrode of the third switch tube is respectively connected to one end of the input capacitor and the cathode of the third diode, the first electrode of the third switch tube is used to receive the input voltage, the second electrode of the third switch tube is respectively connected to the cathode of the fourth diode and the first end of the primary winding, the second end of the primary winding is respectively connected to the anode of the third diode and the first electrode of the fourth switch tube, the second electrode of the fourth switch tube is connected to the anode of the fourth diode, and the second electrode of the fourth switch tube is connected to the other end of the input capacitor with the same potential.

9. The flyback dual-transistor voltage conversion circuit according to claim 1, characterized in that: The primary winding includes a center tap, and a first primary winding and a second primary winding respectively connected to the center tap.

10. The flyback dual-transistor voltage conversion circuit according to claim 1, characterized in that: The auxiliary switch tube is used to enable the auxiliary capacitor to charge the auxiliary winding after being turned on, and to stop the auxiliary capacitor from charging the auxiliary winding after being turned off, and to discharge the auxiliary winding to the primary winding.

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