Switching power supply converter

Abstract

The utility model relates to the technical field of power supply output circuits, and provides a switching power supply converter, which comprises a rectifier module, a PFC (Power Factor Correction) module, a flyback circuit, a voltage feedback module and a PWM (Pulse Width Modulation) control module, the input end of the rectifier module is connected with a power supply input end N, and the output end of the rectifier module is connected with the PFC module; the input end of the PFC module is connected with the output end of the rectifier module and the power supply input end L, the output end is connected with the flyback circuit, and the control end is connected with the PWM control module; a first inductor L1 in a PFC module is connected to a power supply input end L, so that when an alternating current voltage is input in a positive phase, high voltage is generated by using the inductor, and a first capacitor is charged so as to realize boosting of the whole circuit. Meanwhile, energy stored by the first inductor L1 enables the flyback circuit to work from low voltage to high voltage, so that the whole line is enabled to be in a high-voltage working state at least in a half period when low-voltage input is carried out, and the efficiency of the whole line is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power output circuits, in particular to a switching power converter. Background Art

[0002] With the continuous development of electronic technology, more and more electronic products have emerged; correspondingly, there is an increasing pursuit of technology refinement. How to improve the competitiveness of products and how to improve the efficiency conversion of products have become widespread concerns.

[0003] Although the flyback technology is widely used in the field of low power, it still has inherent defects and limitations: First, the power factor of the traditional flyback power supply is not high, and the current utilization rate in the power grid is low; Second, due to its working characteristics, the flyback power supply will generate large current harmonics, which may interfere with other electronic devices.

[0004] With the improvement of technology level, the application of PFC technology can effectively make up for the shortcomings of flyback. The application of PFC technology can significantly improve the power factor of the power supply and further enhance the utilization efficiency of the power supply; PFC technology can adjust the input current waveform to make it more consistent with the input voltage waveform, achieve lower THD (Total Harmonic Distortion), and at the same time reduce the standby power consumption of the system. The combination of PFC technology and flyback can significantly improve the efficiency of the overall power supply. Therefore, integrating PFC technology into flyback has become the direction of technological development; however, simply integrating PFC technology into the flyback circuit will result in a high peak current due to the short charging time of each cycle of the rectifier bridge, which will correspondingly increase the requirement for the capacitance value of the capacitor, and the volume of the capacitor will also increase accordingly. Summary of the Utility Model

[0005] The utility model provides a switching power converter, which solves the technical problems of large volume and low efficiency in the existing fusion scheme of flyback circuit and PFC technology.

[0006] To solve the above technical problems, the utility model provides a switching power converter, which includes a rectification module, a PFC module, a flyback circuit, a voltage feedback module and a PWM control module; the input end of the rectification module is connected to the power input end N, and the output end is connected to the PFC module; the input end of the PFC module is connected to the output end of the rectification module and the power input end L, the output end is connected to the flyback circuit, and the control end is connected to the PWM control module; one end of the voltage feedback module is connected to the output end of the flyback circuit, and the other end is connected to the PWM control module; the PWM control module is also connected to the flyback circuit.

[0007] In a further embodiment, the PFC module includes a first inductor L1, a first switching tube Q1, a first diode D1 and a first capacitor C1;

[0008] One end of the first inductor L1 is connected to the power input terminal L, and the other end is connected to the positive electrode of the first diode D1 and the second end of the first switching transistor Q1.

[0009] The first end of the first switching transistor Q1 is grounded, and the control electrode is connected to the PWM control module.

[0010] The negative electrode of the first diode D1 is connected to the rectification module and the flyback circuit.

[0011] The positive electrode of the first capacitor C1 is connected to the flyback circuit, and the negative electrode is grounded.

[0012] In a further embodiment, the rectification module includes a second diode D2 and a third diode D3. The positive electrode of the second diode D2 is connected to the power input terminal N, and the negative electrode is connected to the PFC module. The positive electrode of the third diode D3 is grounded, and the negative electrode is connected to the power input terminal N.

[0013] In a further embodiment, the voltage feedback module includes an optocoupler emitting element U1A, an optocoupler receiving circuit U1B, and a voltage stabilizing element Q3. The input terminal of the voltage stabilizing element Q3 is connected to the output terminal of the flyback circuit, the output terminal is coupled to the output terminal of the optocoupler emitting element U1A, and the grounding terminal is grounded. The input terminal of the optocoupler emitting element U1A is connected to the output terminal of the flyback circuit. The optocoupler receiving circuit U1B is coupled to the PWM control module.

[0014] In a further embodiment, the flyback circuit includes a transformer T1 and an output module. The primary winding of the transformer T1 is connected to the PWM control module. One end of the secondary winding of the transformer T1 is connected to the output module, the other end is connected to the power supply interface, and is also connected to the voltage feedback module.

[0015] In a further embodiment, the output module includes a fourth diode D4 and a second capacitor C2. The positive electrode of the fourth diode D4 is grounded, and the negative electrode is connected to one end of the secondary winding of the transformer T1. The second capacitor C2 is connected in parallel with the fourth diode D4.

[0016] In a further embodiment, the PWM control module includes a PWM controller and a second switching transistor Q2. The first end of the second switching transistor is grounded, the second end is connected to the primary winding of the transformer T1, and the control end is connected to the PWM controller. The PWM controller is connected to the PFC module and the voltage feedback module.

[0017] In a further embodiment, the second switching transistor Q2 is an N-channel MOS transistor or a P-channel MOS transistor.

[0018] The beneficial effects of the present utility model are as follows:

[0019] A power factor correction (PFC) circuit is added to the circuit. The PFC technology can improve the power factor of the power supply, enabling the electric energy extracted from the power grid by the power supply to be utilized more effectively, reducing energy loss. In addition, the PFC technology can effectively reduce the harmonic pollution of the power grid, is beneficial to reducing electromagnetic interference, and can maintain a low total harmonic distortion.

[0020] The first inductor L1 in the PFC module is connected to the power input terminal L. Thus, when the positive phase of the AC voltage is input, a high voltage is generated by the inductor to charge the first capacitor, realizing the boosting of the overall circuit. At the same time, the energy stored in the first inductor L1 enables the flyback circuit to switch from low voltage to high voltage operation, ensuring that the entire circuit operates at a high voltage for at least half a cycle when the input is low voltage, effectively improving the efficiency of the overall circuit.

[0021] A first inductor L1 connected to the power input terminal L and a half-bridge rectifier connected to the power input terminal N are designed. The first inductor L1 is placed in front of the rectifier bridge. At the same time, the half-bridge rectifier, the first diode D1, and the first switching transistor Q1 form a "full-bridge" rectifier bridge. Compared with traditional single-phase PFC, the circuit requires a larger capacitance value for the capacitor when operating at low frequencies. While further increasing the frequency of the circuit, it avoids the reduction of rectification efficiency due to heat generation, and significantly reduces the capacitance value and volume of the capacitor. Description of the Drawings

[0022] Figure 1 is a system framework diagram of a switching power supply converter provided by an embodiment of the present utility model;

[0023] Figure 2 is provided by an embodiment of the present utility model Figure 1 hardware circuit diagram;

[0024] Among them: rectification module 1, PFC module 2, flyback circuit 3, voltage feedback module 4, PWM control module 5, filtering module 6, PWM controller U1. Specific Embodiments

[0025] The following specifically illustrates the embodiments of the present utility model in conjunction with the drawings. The given embodiments are only for illustrative purposes and should not be construed as limitations on the present utility model. The included drawings are only for reference and illustration, and do not constitute a limitation on the scope of patent protection of the present utility model, because many changes can be made to the present utility model without departing from its spirit and scope.

[0026] A switching power supply converter provided by an embodiment of the present utility model, such as Figure 1 、 Figure 2As shown, in this embodiment, it includes a rectification module 1, a PFC module 2, a flyback circuit 3, a voltage feedback module 4, and a PWM control module 5; the input end of the rectification module 1 is connected to the power input end N, and the output end is connected to the PFC module 2; the input end of the PFC module 2 is connected to the output end of the rectification module 1 and the power input end L, the output end is connected to the flyback circuit 3, and the control end is connected to the PWM control module 5; one end of the voltage feedback module 4 is connected to the output end of the flyback circuit 3, and the other end is connected to the PWM control module 5; the PWM control module 5 is also connected to the flyback circuit 3.

[0027] In this embodiment, the PFC module 2 includes a first inductor L1, a first switching transistor Q1, a first diode D1, and a first capacitor C1;

[0028] One end of the first inductor L1 is connected to the power input end L, and the other end is connected to the positive electrode of the first diode D1 and the second end of the first switching transistor Q1;

[0029] The first end of the first switching transistor Q1 is grounded, and the control electrode is connected to the PWM control module 5;

[0030] The negative electrode of the first diode D1 is connected to the rectification module 1 and the flyback circuit 3;

[0031] The positive electrode of the first capacitor C1 is connected to the flyback circuit 3, and the negative electrode is grounded.

[0032] In this embodiment, the rectification module 1 includes a second diode D2 and a third diode D3. The positive electrode of the second diode D2 is connected to the power input end N, and the negative electrode is connected to the PFC module 2; the positive electrode of the third diode D3 is grounded, and the negative electrode is connected to the power input end N.

[0033] In this embodiment, the voltage feedback module 4 includes an optocoupler emission element U1A, an optocoupler receiving circuit U1B, and a voltage stabilizing element Q3; the input end of the voltage stabilizing element Q3 is connected to the output end of the flyback circuit 3, the output end is coupled to the output end of the optocoupler emission element U1A, and the grounding end is grounded; the input end of the optocoupler emission element U1A is connected to the output end of the flyback circuit 3; the optocoupler receiving circuit U1B is coupled to the PWM control module 5.

[0034] Among them, the voltage stabilizing element Q3 includes, but is not limited to, an operational amplifier comparator and a voltage regulator. The voltage regulator includes a TL431 voltage regulator and a TL432 voltage regulator.

[0035] The voltage feedback module 4 performs voltage feedback through an optocoupler, conducts electrical isolation and signal transmission, and has strong anti-interference ability and good stability and reliability.

[0036] In this embodiment, the flyback circuit 3 includes a transformer T1 and an output module. The primary winding of the transformer T1 is connected to the PWM control module 5; one end of the secondary winding of the transformer T1 is connected to the output module, and the other end is connected to the power supply interface and is also connected to the voltage feedback module 4.

[0037] In this embodiment, the output module includes a fourth diode D4 and a second capacitor C2; the positive electrode of the fourth diode D4 is grounded, and the negative electrode is connected to one end of the secondary winding of the transformer T1; the second capacitor C2 is connected in parallel with the fourth diode D4.

[0038] In this embodiment, the PWM control module 5 includes a PWM controller U1 and a second switching transistor Q2; the first end of the second switching transistor is grounded, the second end is connected to the primary winding of the transformer T1, and the control end is connected to the PWM controller U1; the PWM controller U1 is connected to the PFC module 2 and the voltage feedback module 4.

[0039] In this embodiment, the first switching transistor Q1 and the second switching transistor Q2 can be selected as N-channel MOS transistors or P-channel MOS transistors according to requirements.

[0040] In this embodiment, to improve the power output quality, a filtering module 6 is further included. The filtering module 6 includes a third capacitor C3. One end of the third capacitor C3 is connected to the output end of the flyback circuit 3, and the other end is grounded.

[0041] Taking the first switching transistor Q1 and the second switching transistor Q2 both being N-channel MOS transistors as an example, the working principle of this embodiment is as follows:

[0042] At time T0, that is, when the power supply is connected, the first switching transistor Q1 of the PFC is in the off state, and the current flows through the first inductor L1 and the first diode D1 to charge the first capacitor C1. At the same time, the flyback circuit 3 enters the working state, that is, by controlling the PWM controller U1 to drive the second switching transistor Q2 to conduct and turn off. When the second switching transistor Q2 conducts, the transformer T1 stores energy. At this time, due to the unidirectional conduction characteristic of the fourth diode D4, there is no output on the secondary side; when the second switching transistor Q2 turns off, due to the change of the magnetic field of the transformer T1, an induced voltage is generated in the secondary winding, and the energy stored in the primary winding is output to the load through the secondary winding.

[0043] At time T1, the positive phase of the AC voltage is input, and the first switching transistor Q1 is turned on. At this time, due to the charging at time T0, the cathode of the first diode D1 is at a higher potential than the anode, so the first diode D1 is not turned on at this time; while the drain of the first switching transistor Q1 is at a higher potential than the source, so the current flows from the first inductor L1 through the first switching transistor Q1, forming a closed loop with the third diode D3; as the current increases, the magnetic field of the first switching transistor Q1 strengthens, enabling the first switching transistor Q1 to store energy. During the energy storage process of the first switching transistor Q1, the flyback circuit 3 is still in the working state, and the first capacitor C1 provides energy for the load.

[0044] At time T2, the first switching transistor Q1 is turned off, and the AC input is still in the positive phase. Since the current at both ends of the inductor cannot change suddenly, when the first switching transistor Q1 is turned off, the first inductor L1 will induce a high voltage. At this time, the anode potential of the first diode D1 is higher than the cathode potential, causing the first diode D1 to conduct. The energy stored in the first inductor L1 during the conduction of the first switching transistor Q1 is released to charge the first capacitor C1; achieving the step-up of the overall circuit. At the same time, the energy stored in the first inductor L1 enables the flyback circuit to switch from low voltage to high voltage operation.

[0045] At time T3, the AC voltage is input in the negative phase. When the capacitor voltage is greater than √2Vin, the first capacitor C1 continuously discharges to provide power for the load; when the capacitor voltage is lower than √2Vin, there is a voltage difference between the capacitor voltage and the AC input voltage; the first switching transistor Q1 is turned on, and the second diode D2, the first switching transistor Q1, the first inductor L1, and the first capacitor C1 form a loop; the charging current generated by the input flows in from the second diode D2 to charge the first capacitor C1; when the capacitor voltage charges and stores energy greater than √2Vin, the first switching transistor Q1 is turned off again, in a cyclic discharge process.

[0046] The beneficial effects of the embodiments of the present utility model are as follows:

[0047] A power factor correction (PFC) circuit is added to the circuit. PFC technology can improve the power factor of the power supply, enabling the electric energy extracted from the power grid by the power supply to be utilized more effectively, reducing energy loss; in addition, PFC technology can effectively reduce the harmonic pollution of the power grid, is beneficial to reducing electromagnetic interference, and can maintain a low total harmonic distortion.

[0048] The first inductor L1 in the PFC module 2 is connected to the power input terminal L, so that when the positive phase of the AC voltage is input, a high voltage is generated by the inductor to charge the first capacitor to achieve the step-up of the overall circuit. At the same time, the energy stored in the first inductor L1 enables the flyback circuit 3 to switch from low voltage to high voltage operation, enabling the entire circuit to operate at a high voltage for at least half a cycle when the input is low voltage, effectively improving the efficiency of the overall circuit.

[0049] Design a first inductor L1 connected to the power input terminal L and a half-bridge rectifier bridge connected to the power input terminal N respectively. Place the first inductor L1 in front of the rectifier bridge. At the same time, let the half-bridge rectifier bridge, the first diode D1 and the first switching transistor Q1 form a "full-bridge" rectifier bridge. Compared with the traditional single-phase PFC, when the circuit operates at low frequency, a larger capacitance value of the capacitor is required. While further increasing the frequency of the circuit, it avoids the rectification efficiency being affected by heat generation, and significantly reduces the capacitance value and volume of the capacitor.

[0050] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A switching power supply converter, characterized in that: It includes a rectification module, a PFC module, a flyback circuit, a voltage feedback module, and a PWM control module; the input end of the rectification module is connected to the power input terminal N, and the output end is connected to the PFC module; the input end of the PFC module is connected to the output end of the rectification module and the power input terminal L, the output end is connected to the flyback circuit, and the control end is connected to the PWM control module; one end of the voltage feedback module is connected to the output end of the flyback circuit, and the other end is connected to the PWM control module; the PWM control module is also connected to the flyback circuit.

2. The switching power supply converter according to claim 1, wherein: The PFC module includes a first inductor L1, a first switching transistor Q1, a first diode D1, and a first capacitor C1; One end of the first inductor L1 is connected to the power input terminal L, and the other end is connected to the positive electrode of the first diode D1 and the second end of the first switching transistor Q1; The first end of the first switching transistor Q1 is grounded, and the control electrode is connected to the PWM control module; The negative electrode of the first diode D1 is connected to the rectification module and the flyback circuit; The positive electrode of the first capacitor C1 is connected to the flyback circuit, and the negative electrode is grounded.

3. The switching power supply converter according to claim 2, characterized in that: The rectification module includes a second diode D2 and a third diode D3. The positive electrode of the second diode D2 is connected to the power input terminal N, and the negative electrode is connected to the PFC module; the positive electrode of the third diode D3 is grounded, and the negative electrode is connected to the power input terminal N.

4. The switching power supply converter according to claim 1, wherein: The voltage feedback module includes an optocoupler emitting element U1A, an optocoupler receiving circuit U1B, and a voltage stabilizing element Q3; the input end of the voltage stabilizing element Q3 is connected to the output end of the flyback circuit, the output end is coupled to the output end of the optocoupler emitting element U1A, and the grounding end is grounded; the input end of the optocoupler emitting element U1A is connected to the output end of the flyback circuit; the optocoupler receiving circuit U1B is coupled to the PWM control module.

5. The switching power supply converter according to claim 4, characterized in that: The flyback circuit includes a transformer T1 and an output module. The primary winding of the transformer T1 is connected to the PWM control module; one end of the secondary winding of the transformer T1 is connected to the output module, the other end is connected to the power supply interface, and is also connected to the voltage feedback module.

6. The switching power supply converter according to claim 5, characterized in that: The output module includes a fourth diode D4 and a second capacitor C2; the positive electrode of the fourth diode D4 is grounded, and the negative electrode is connected to one end of the secondary winding of the transformer T1; the second capacitor C2 is connected in parallel with the fourth diode D4.

7. A switching power supply converter according to claim 5, characterized in that: The PWM control module includes a PWM controller and a second switching transistor Q2; the first end of the second switching transistor is grounded, the second end is connected to the primary winding of the transformer T1, and the control end is connected to the PWM controller; the PWM controller is connected to the PFC module and the voltage feedback module.

8. A switching power supply converter according to claim 7, characterized in that: The second switching transistor Q2 is an N-channel MOS transistor or a P-channel MOS transistor.

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