Power conversion circuit and lighting device

Abstract

The invention relates to the technical field of control circuits, in particular to a power conversion circuit and a lighting device. The power conversion circuit comprises an input end, a rectifier module, a power inductor module and a parallel module. The rectifier module is connected with the input end; the power inductor module comprises a first end, a second end and a third end located between the first end and the second end; the parallel module is connected between the rectifier module and the power inductor module, the parallel module comprises a first conduction loop and a second conduction loop, one end of the first conduction loop is connected with the rectifier module, and the other end of the first conduction loop is connected with the third end of the power inductor module; one end of the second conduction loop is connected with the rectification module, and the other end is connected with the second end of the power inductance module. The power conversion circuit can effectively improve the power factor of the circuit, and can be suitable for isolated / non-isolated circuits with different structures.

Description

Technical Field

[0001] This invention relates to the field of control circuit technology, and more specifically to a power conversion circuit and a lighting device. Background Technology

[0002] In the power supply circuits of lighting devices such as LEDs, isolation circuits are typically included for signal transmission and power conversion. These isolation circuits use control and drive circuits to sample the primary-side signal to calculate the output current and perform power factor correction. However, the aforementioned circuit adjustment and control methods are only suitable for flyback isolated topologies and require a dedicated control chip to assist in implementation.

[0003] like Figure 1 As shown, in the buck-boost circuit provided by the prior art, the rectifier bridge BD 01 The input alternating current is converted into smooth direct current, which is the power inductor L. 01 And power supply for the subsequent load. Input voltage V in Greater than the electrolytic capacitor C 01 When the voltage across the terminals is equal to the voltage across the power inductor L at the downstream end, 01 The circuit is activated, thus supplying energy to the subsequent load. In other words, in the rectifier bridge BD... 01 During the conduction period, the aforementioned non-isolated buck-boost circuit will only have an input current I. in Generate, input current I in Work is done to produce active power. In summary, in the above circuit, the rectifier bridge BD... 01 The non-conducting time is relatively long, and correspondingly, the effective work time of a non-isolated buck-boost circuit is shorter, resulting in a lower power factor. Summary of the Invention

[0004] To address the above problems, this invention provides a power conversion circuit and a lighting device. The power conversion circuit can effectively improve the power factor of the circuit and is applicable to circuits with different structures, such as isolated and non-isolated circuits.

[0005] The present invention provides a power conversion circuit, including an input terminal, a rectifier module, a power inductor module, and a parallel module. The rectifier module is connected to the input terminal; the power inductor module includes a first terminal, a second terminal, and a third terminal located between the first and second terminals; the parallel module is connected between the rectifier module and the power inductor module, and includes a first conducting loop and a second conducting loop. The first conducting loop includes a first inductor and a first diode connected in series, the anode of the first diode is connected to the rectifier module, and the cathode is connected to the third terminal of the power inductor module; one end of the second conducting loop is connected to the rectifier module, and the other end is connected to the first terminal of the power inductor module.

[0006] According to the technical solution of the present invention, the input terminal transmits the AC input voltage to the rectifier module to convert it into DC voltage. The rectified DC voltage is then transmitted to the power inductor module and subsequent load units via the parallel module. As the DC voltage gradually changes from low to high, the first conducting loop in the parallel module conducts first. When the first conducting loop is conducting, the current flows sequentially through the first inductor, the first diode, and the third terminal to the second terminal of the power inductor module, i.e., the power inductor module is partially conducting, and the input current begins to be generated. As the DC voltage increases, the second conducting loop conducts. When the second conducting loop is conducting, the current flows directly from the rectifier module to the power inductor module, generating the input current to perform work. By superimposing the current amplitude, conduction time, and rise rate, the effective value of the current is improved. At the same time, by using the power loop with less voltage division, i.e., the first conducting loop, the conduction time that can generate the output current is extended. This reduces the peak value of the output current, improves the effective value of the output current, and thus reduces harmonic components and improves the power factor of the circuit.

[0007] Preferably, in the technical solution of the present invention, the power conversion circuit further includes a control chip, and the output pin of the control chip is connected to the second end of the power inductor module.

[0008] According to the technical solution of the present invention, the control chip can send control signals to the power inductor module to assist in control.

[0009] Preferably, in the technical solution of the present invention, the inductance between the third terminal and the second terminal in the power inductor module is equal to one-tenth to one-half of the inductance between the first terminal and the second terminal.

[0010] According to the technical solution of the present invention, when the first conducting loop is turned on, its voltage and current are related to the inductance value in the circuit. The power inductor module is turned on only in part between the third terminal and the second terminal. By controlling the setting position of the third terminal, the conducting inductance value of the power inductor module can be adjusted, thereby adjusting the current value in the first conducting loop, and further adjusting the input current of the power conversion circuit to improve the power factor.

[0011] Furthermore, in the technical solution of the present invention, the inductance between the first terminal and the third terminal in the power inductor module is equal to one-quarter of the inductance between the first terminal and the second terminal.

[0012] Preferably, in the technical solution of the present invention, the inductance of the first inductor is 1-10 times the inductance of the power inductor module.

[0013] According to the technical solution of the present invention, when the first conducting circuit and the second conducting circuit are connected in parallel, their voltage and current are related to the inductance value of the parallel part. The part between the third terminal and the first terminal in the first inductor module is connected in parallel. By controlling the setting position of the third terminal and the inductance value of the first inductor, the conducting inductance value of the power inductor module can be adjusted, thereby adjusting the current value and voltage value in the circuit, and further adjusting the input current of the power conversion circuit to improve the power factor.

[0014] Furthermore, in the technical solution of this invention, the inductance of the first inductor is twice the inductance of the power inductor module. Experiments have verified that when the inductance of the first inductor in the power inductor module is twice the inductance of the power inductor module, the power factor of the power conversion circuit is the highest.

[0015] In the technical solution of this invention, the second conduction loop in the power conversion circuit includes a second diode. The anode of the second diode is connected to the rectifier module, and the cathode is connected to the first terminal of the power inductor module. When the second conduction loop is turned on, current flows sequentially through the second diode and the first terminal of the power inductor module to the second terminal.

[0016] In the technical solution of this invention, the power inductor module in the power conversion circuit can also be used as the input winding of an isolation transformer.

[0017] According to the technical solution of the present invention, the power conversion circuit adjusts the power factor by adjusting the size of the inductor in the circuit, and can be applied to circuits with different structures such as isolated and non-isolated types.

[0018] In the technical solution of the present invention, a lighting device is also provided, the driving circuit of which includes the power conversion circuit described above. Attached Figure Description

[0019] Figure 1 This is a circuit diagram of a buck-boost circuit provided in the prior art.

[0020] Figure 2 This is a waveform diagram of a buck-boost circuit provided in the prior art.

[0021] Figure 3 This is a circuit diagram of a power conversion circuit provided in the first and second embodiments of the present invention.

[0022] Figure 4 These are waveform comparison diagrams of a power conversion circuit provided in the first and second embodiments of the present invention.

[0023] Figure 5 This is a circuit diagram of a power conversion circuit provided in the third embodiment of the present invention.

[0024] Figure labeling: 1-Input terminal, 2-Rectifier module, 3-Power inductor module, 4-Parallel module, 5-Control module. Detailed Implementation

[0025] First, it should be noted that the following will illustrate the composition, working principle, characteristics and advantages of the power conversion circuit and lighting device according to this application by way of example. However, it should be understood that all descriptions are given for illustrative purposes only and should not be construed as forming any limitation on this application.

[0026] Furthermore, for any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature shown or implied in the various figures, this application still allows for any combination or deletion of these technical features (or their equivalents) without any technical obstacle, thereby obtaining more other embodiments of this application that may not be directly mentioned herein.

[0027] like Figure 1 As shown, in the prior art, in a non-isolated buck-boost circuit, the rectifier bridge BD... 01 The filter circuit converts the input AC current into smooth DC current, at which point the electrolytic capacitor C... 01 The voltage across the terminals can be equivalent to that of the power inductor L. 01 The voltage, output voltage V in Greater than the electrolytic capacitor C 01 When the voltage across the terminals is L, the power inductor L 01 The circuit is open, generating an output current I. in This provides power to the downstream load.

[0028] Figure 2 This is a waveform diagram of a buck-boost circuit provided in the prior art.

[0029] Specifically, refer to Figure 2 And Table 1 below, input voltage V in It changes periodically over time, as... Figure 1 Taking the buck-boost circuit shown as an example, let the input voltage V in The effective value is 220V, and a simulation test was conducted. The experimental results show that the input voltage V... in Greater than the electrolytic capacitor C 01 Voltage V across the terminals c01 When, the electrolytic capacitor C 01 Fully charged, input voltage V in Only then can the electrolytic capacitor C be connected. 01 The circuit connected afterwards supplies power, and only then will there be an input current I in a non-isolated buck-boost circuit. inThe input current I was generated and measured experimentally. in The effective value is 0.0409A, and the input current I in Work is done to produce active power. In the circuit above, the input threshold voltage V C01 High, input voltage V in Greater than the input threshold voltage V C01 The conduction time is only t 01 -t 02 and t 03 -t 04 Non-isolated buck-boost circuits have a shorter effective work time and a lower power factor, experimentally measured at only 0.4897. Furthermore, the input current I... in The peak time corresponding to t max The corresponding phase angle is 74.5°, which is related to the output voltage V. in The phase difference is as high as 15.5°, and the circuit has high harmonic components.

[0030] <![CDATA[V in ]]> 220 Total Harmonic 180.30％ <![CDATA[I in ]]> 0.0409 2 times 0.20％ <![CDATA[P in ]]> 4.41 3 times 96.20％ <![CDATA[P F ]]> 0.4897 5 times 86.70％ <![CDATA[V o ]]> 24 7 times 74.70％ <![CDATA[I o ]]> 0.1634 9 times 61.00％ <![CDATA[P o ]]> 3.9216 11 times 47.40％ η 88.93％ 13 times 35.50％

[0031] Table 1 Test data of buck-boost circuits in the prior art

[0032] [First Implementation Method]

[0033] Figure 3 This is a schematic diagram of a power conversion circuit provided in the first embodiment of the present invention.

[0034] like Figure 3 As shown, in the first embodiment of the present invention, a power conversion circuit is provided for output control and power factor adjustment. The power conversion circuit includes an input terminal 1, a rectifier module 2, a power inductor module 3, and a parallel module 4.

[0035] In the first embodiment of the present invention, input terminal 1 is connected to an external power supply to receive an input AC signal. Rectifier module 2 is connected to input terminal 1 and is used to convert the AC power from input terminal 1 into smooth DC power. Rectifier module 2 includes a rectifier bridge BD, a diode D1 and a capacitor C1 connected in series, a resistor R1 connected in parallel with diode D1, and an input capacitor C connected in parallel. 02 and input capacitor C 03 The parallel resistor R2 and inductor L1 are connected to the input capacitor C. 02 and input capacitor C 03 Between them. The rectifier bridge BD rectifies the AC power input at input terminal 1. The subsequent filter unit, composed of capacitors, resistors, inductors, and other components, filters the DC signal rectified by the rectifier bridge BD to obtain smooth DC power to supply power to the subsequent connected circuits and components.

[0036] In the first embodiment of the present invention, the power inductor module 3 is configured as a power inductor L2. The inductance and other parameters of the power inductor L2 are related to the number of turns in its coil; for example, the inductance is proportional to the number of turns. The power inductor L2 includes a first terminal a, a second terminal b, and a third terminal c located between the first terminal a and the second terminal b. The inductance between the first terminal a and the second terminal b in the power inductor L2 remains constant. Depending on the withdrawal position of the third terminal c, the number of turns in the coil between the third terminal c and the second terminal b can be adjusted, thereby achieving adjustment of the conduction parameters. In this embodiment, the inductance of the third terminal c is set to...

[0037] In the first embodiment of the present invention, the parallel module 4 is connected between the rectifier module 2 and the power inductor module 3. The rectifier module 2 is connected to the power inductor module 3 through one or more loops in the parallel module 4. The parallel module 4 includes a first conducting loop 41 and a second conducting loop 42. One end of the first conducting loop 41 is connected to the rectifier module 2, and the other end is connected to the third terminal c of the power inductor L2. When the first conducting loop 41 is conducting, the portion between the third terminal c and the second terminal b of the power inductor L2 is conducting. One end of the second conducting loop 42 is connected to the rectifier module 2, and the other end is connected to the portion between the first terminal a and the second terminal b of the power inductor L2, i.e., the power inductor L2 is fully conducting. When the second conducting loop 42 is conducting, the second conduction voltage V of the power inductor L2 is... ab Equal to capacitor voltage V C0 When the first conduction circuit 41 is turned on, the first conduction voltage V of the power inductor L2 is... bc equal Capacitor voltage V C0 .

[0038] In a first embodiment of the present invention, the first conduction circuit 41 includes a first inductor L3 and a first diode D3 connected in series. One end of the first inductor L3 is connected to the rectifier module 2, and the other end is connected to the anode of the first diode D3. The anode of the first diode D3 is connected to the first inductor L3, and the cathode is connected to the third terminal c of the power inductor L2. When the first conduction circuit 41 is turned on, the first current I1 flows sequentially through the first inductor L3, the first diode D3, and the third terminal c and the second terminal b of the power inductor L2.

[0039] The first inductor L3 is preferably an inductor with adjustable inductance to adapt to different power factor adjustment circuits and improve the power factor improvement effect. The first diode D3 is used to limit the direction of inductor current flow in the first conduction circuit 41.

[0040] In a first embodiment of the present invention, the second conduction circuit 42 includes a second diode D2 for limiting the direction of inductor current flow in the second conduction circuit 42. The anode of the second diode D2 is connected to the rectifier module 2, and the cathode is connected to the first terminal a of the power inductor L2. When the second conduction circuit 42 is turned on, the second current I2 flows sequentially through the second diode D2 and the first terminal a to the second terminal b of the power inductor L2.

[0041] Figure 4 This is a waveform comparison diagram of a power conversion circuit provided in the second embodiment of the present invention.

[0042] refer to Figure 4 And Table 2 below, Figure 4 The upper middle section shows a schematic diagram of the voltage and current waveforms in this embodiment, while the lower section shows a schematic diagram of the voltage and current waveforms in the prior art. In the first embodiment of the present invention, the input voltage V... in It varies periodically over time, with an effective value of 220V. Input voltage V in Less than Capacitor voltage V C0 At this time, no input current is generated in the power inductor L2; the input voltage V in Greater than Capacitor voltage V C0 When the first conduction circuit 41 is turned on, input current I is generated at input terminal 1. in That is, the first current I1. According to the inductor voltage law V / L=di / dt, when the inductance L and the conduction time T on When fixed, the first current I1 will follow the input voltage V. in It changes accordingly. During the period when the first conducting circuit 41 is on, the input voltage is a sine wave, and the first current I1 will also appear in a similar sine wave shape. Input voltage V in Greater than capacitor voltage V C0 When the second conducting circuit 42 is turned on, a second current I2 is generated. The second conducting circuit 42 and... Figure 1 The conducting loop in the circuit shown is the same, and the waveform of the second current I2 is the same as... Figure 2 The current waveforms shown are similar. The first conducting loop 41 and the second conducting loop 42 are connected in parallel, and the input current I... in = First current I1 + Second current I2.

[0043] In the above circuit, the input threshold voltage is Only the input threshold voltage V in the existing technology C One-quarter of the input voltage V. in Voltage greater than the input threshold The conduction time is t1-t2. A significant decrease in the input threshold voltage greatly increases the conduction time, resulting in an output current I.in The increase in the effective work time of the circuit increases, thereby improving the power factor of the circuit. Furthermore, the input current I... in The peak time corresponding to t max The corresponding phase angle is 82°, which is related to the output voltage V. in The phase difference is reduced to 8°, and the harmonic components in the circuit are also greatly reduced.

[0044] <![CDATA[V in ]]> 220 Total Harmonic 66.30％ <![CDATA[I in ]]> 0.0277 2 times 0.20％ <![CDATA[P in ]]> 4.92 3 times 59.20％ <![CDATA[P F ]]> 0.7997 5 times 23.30％ <![CDATA[V o ]]> 24 7 times 12.00％ <![CDATA[I o ]]> 0.1634 9 times 6.60％ <![CDATA[P o ]]> 3.9216 11 times 3.50％ η 79.71％ 13 times 7.00％

[0045] Table 2 Test Data of Power Conversion Circuit in the First Embodiment

[0046] Preferably, in the first embodiment of the present invention, the power conversion circuit further includes a control chip 5. The output pin of the control chip 5 is connected to the second end of the power inductor module 3. The control chip 5 can send control signals to the power inductor module 3 to perform auxiliary control, output adjustment and other actions.

[0047] In embodiments of the present invention, the control chip 5 may be a chip or circuit of different types and configurations, such as an MCU or a PFC controller, and no limitation is imposed here.

[0048] In an embodiment of the present invention, the windings of the power inductor module 3 are split and combined with the parallel module 4 to form different parallel power circuits. Furthermore, the different current rise rates of these different power circuits result in the superposition of the effective current values ​​(first current I1 + second current I2). Simultaneously, the first conducting circuit 41, which has a smaller voltage division, improves the ability to generate the output current I. in The conduction time is reduced, thereby decreasing the output current I. in The peak value increased the output current I. in The effective value of the circuit is reduced, thus decreasing harmonic components and improving the power factor of the circuit.

[0049] [Second Implementation Method]

[0050] In a second embodiment of the present invention, a power conversion circuit is provided for output control and power factor adjustment, and its circuit structure is the same as that of the first embodiment.

[0051] In the second embodiment of the present invention, when only the first conducting loop 41 is conducting in the power conversion circuit, the inductance in the circuit is the first inductance L3 plus the portion of the inductance L between the third terminal c and the second terminal b of the power inductance L2. bc When the first conducting loop 41 and the second conducting loop 42 are connected in parallel, the inductance in the first conducting loop 41 is L3 + L. bc The inductance in the second conducting loop 42 is L2 = L ab +Lbc L3 and L ab Parallel connection with L bc Series connection.

[0052] In summary, the inductance in the power conversion circuit is related to the inductance L3 and the portion of the inductance L between the third terminal c and the second terminal b of the power inductor L2. bc Directly related. According to the inductor voltage law V / L = di / dt, the circuit's output voltage V in and output current I in This will also change accordingly, thereby adjusting the power factor of the power conversion circuit. Therefore, in the above circuit, controlling L3 and L... bc The choice of numerical values ​​is particularly important.

[0053] On the one hand, with the first inductor L3 being 1mH and the power inductor L2 remaining constant at 0.5mH, adjusting the setting position of the third terminal c of the power inductor L2 can adjust the conduction inductance value of the power inductor module 3, thereby increasing the inductance L between the third terminal c and the second terminal b of the power inductor L2. b Set as power inductor L2 arrive Any value between [the specified values]. For example, the inductance L between the third terminal c and the second terminal b of the power inductor L2. bc They are respectively set as power inductor L2 The data obtained from the experiment are shown in Table 3 below.

[0054]

[0055]

[0056] Table 3 Test Data Table of Power Conversion Circuit in the Second Embodiment

[0057] (The control variable is L) bc )

[0058] As shown in Table 3 above, compared to Figure 1 The power factor of the circuit in the prior art shown is 0.4897. Adding a parallel loop 4 and connecting the inductance L between the third terminal c and the second terminal b of the power inductor L2... bc They are respectively set as power inductor L2 At that time, its power factor P F The values ​​are 0.6997, 0.7997, and 0.755 respectively, all showing significant improvement. Similarly, the inductance L between the third terminal c and the second terminal b of the power inductor L2... bc They are respectively set as power inductor L2 At that time, the total harmonics were 90.30%, 66.30%, and 83.70%, respectively, which is a significant reduction compared to 180.30% in the prior art, making the circuit operation more stable.

[0059] Furthermore, in the second embodiment of the present invention, the inductance L between the third terminal c and the second terminal b of the power inductor L2... bc Set as power inductor L2 At that time, the power factor P of the power conversion circuit F The highest harmonic content and the lowest harmonic content. In other words, the inductance L between the third terminal c and the second terminal b of the power inductor L2 is the highest. bc Set as power inductor L2 At this time, it can maximize the conduction time, reduce the peak value of the output current, and increase the effective value of the output current, thereby achieving the optimal effect of reducing harmonic components and improving the power factor of the circuit.

[0060] On the other hand, given that the power inductor L2 is determined to be 0.5mH and the inductance L between the third terminal c and the second terminal b of the power inductor L2... bc Set as power inductor L2 To achieve the optimal value, set the inductance L between the third terminal c and the second terminal b of the power inductor L2. bc Set as power inductor L2 Keeping the inductance constant, the inductance value of the first inductor L3 was adjusted to 0.82mH, 1mH, 1.8mH, and 3mH respectively. The data in Table 4 below can be obtained through experiments.

[0061]

[0062]

[0063] Table 4 Test Data Table of Power Conversion Circuit in the Second Embodiment

[0064] (The control variable is L3)

[0065] As shown in Table 4 above, compared to Figure 1 The power factor of the circuit in the prior art shown is 0.4897. When a parallel circuit 4 is added and the inductance value of the first inductor L3 is adjusted to 0.82mH, 1mH, 1.8mH, and 3mH respectively, its power factor P... F The values ​​were 0.788, 0.7997, 0.7688, and 0.7238, respectively, all showing significant improvement. Similarly, when the inductance value of the first inductor L3 was adjusted to 0.82mH, 1mH, 1.8mH, and 3mH, respectively, the total harmonic distortion P... FThe percentages are 75.20%, 66.30%, 80.20%, and 92.60%, respectively, which is a significant reduction compared to the 180.30% in the prior art, making the circuit operation more stable.

[0066] Furthermore, in the second embodiment of the present invention, when the inductance value of the first inductor L3 is equal to 1mH, that is, when the inductance value of the first inductor L3 is twice that of the power inductor L2, the power factor P of the power conversion circuit is... F It has the highest harmonic content and the lowest harmonic components.

[0067] In summary, experimental results demonstrate that by setting up parallel circuit 4, and defining the inductance L between the third terminal c and the second terminal b of the power inductor L2, the problem can be solved. bc Set as power inductor L2 Furthermore, when the inductance value of the first inductor L3 is twice that of the power inductor L2, the conduction time can be extended to the maximum extent, the peak value of the output current can be reduced, and the effective value of the output current can be increased. This can improve the power factor of the power conversion circuit to above 0.7, while reducing the harmonic components to below 100%, thereby achieving the optimal effect of reducing harmonic components and improving the power factor of the circuit.

[0068] [Third Implementation Method]

[0069] Figure 5 This is a waveform diagram of a power conversion circuit provided in the third embodiment of the present invention.

[0070] like Figure 5 As shown, in the third embodiment of the present invention, a power conversion circuit is provided, which includes an input terminal 1, a rectifier module 2, a power inductor module 3, a parallel module 4, and a control chip 5. Unlike the scheme in the first embodiment, in this embodiment, the power inductor module 3 in the power conversion circuit is the input winding of an isolation transformer.

[0071] In the third embodiment of the present invention, input terminal 1 is configured as a transformer for connection to an external power source to receive input AC signals. Rectifier module 2 is connected to input terminal 1, and rectifier module 2 includes a rectifier bridge BD and a parallel input capacitor C. 04 The rectifier bridge BD rectifies the AC power input at input terminal 1, and the subsequent input capacitor C... 04 The DC signal obtained by the rectifier bridge BD is filtered to obtain a smooth DC power supply for the subsequent connected circuits and components.

[0072] In the third embodiment of the present invention, a transformer including an input winding L4 and an output winding L5 is provided, and the power inductor module 3 is configured as the input winding L4 of the transformer D. The input winding L4 includes a first terminal a, a second terminal b, and a third terminal c located between the first terminal a and the second terminal b. Depending on the withdrawal position of the third terminal c, the number of coil turns between the third terminal c and the second terminal b can be adjusted, thereby realizing the adjustment of the conduction parameters.

[0073] In the third embodiment of the present invention, the parallel module 4 is connected between the rectifier module 2 and the power inductor module 3. The rectifier module 2 is connected to the power inductor module 3 through one or more loops in the parallel module 4. The parallel module 4 includes a first conducting loop 41 and a second conducting loop 42. One end of the first conducting loop 41 is connected to the rectifier module 2, and the other end is connected to the third end c of the input winding L4. When the first conducting loop 41 is conducting, the portion of the input winding L4 between the third end c and the second end b is conducting. One end of the second conducting loop 42 is connected to the rectifier module 2, and the other end is connected to the portion of the input winding L4 between the first end a and the second end b. When the second conducting loop 42 is conducting, the input winding L4 is fully conducting.

[0074] In the third embodiment of the present invention, the first conduction circuit 41 includes a first inductor L6 and a first diode D6 connected in series. One end of the first inductor L6 is connected to the rectifier module 2, and the other end is connected to the anode of the first diode D6. The anode of the first diode D6 is connected to the first inductor L6, and the cathode is connected to the third terminal c of the input winding L4. When the first conduction circuit 41 is turned on, the first current I1 flows sequentially through the first inductor L6, the first diode D6, and the third terminal c and the second terminal b of the input winding L4. When the second conduction circuit 42 is turned on, the second current I2 flows through the first terminal a and the second terminal b of the input winding L4.

[0075] As shown in the first embodiment, the power conversion circuit adjusts the power factor by adjusting the size of the inductor in the circuit. The technical solution of the present invention can be applied to circuits with different structures such as isolated and non-isolated types.

[0076] Similar to the first embodiment, adjusting the position of the third terminal c of the input winding L4 can adjust the conduction inductance value of the power inductor module 3. Preferably, in this embodiment, the inductance L between the third terminal c and the second terminal b of the input winding L4 is adjusted. b Set as input winding L4 arrive Any value between; set the inductance value of the first inductor L6 to 1-10 times the inductance value of the input winding L4.

[0077] Experimental verification shows that by setting up parallel circuit 4 and defining the inductance L between the third terminal c and the second terminal b of the input winding L4, the problem can be solved.bc Set as input winding L4 Furthermore, when the inductance value of the first inductor L6 is twice that of the input winding L4, the conduction time can be extended to the maximum extent, the peak value of the output current can be reduced, and the effective value of the output current can be increased, thereby achieving the optimal effect of reducing harmonic components and improving the power factor of the circuit.

[0078] In an embodiment of the present invention, a lighting device is also provided, the driving circuit of which includes the power conversion circuit described in the above embodiments.

[0079] The technical solution of the present invention has now been described in conjunction with the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to the specific embodiments described above. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions resulting from such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A power conversion circuit, characterized in that, include Input terminal; The rectifier module is connected to the input terminal; A power inductor module includes a first terminal, a second terminal, and a third terminal located between the first terminal and the second terminal; and A parallel module is connected between the rectifier module and the power inductor module. The parallel module includes: A first conducting circuit, comprising a first inductor and a first diode connected in series, wherein the anode of the first diode is connected to the rectifier module, and the cathode is connected to the third terminal of the power inductor module; and The second conducting loop has one end connected to the rectifier module and the other end connected to the first end of the power inductor module.

2. The power conversion circuit according to claim 1, characterized in that, The second conduction circuit includes a second diode, the anode of which is connected to the rectifier module and the cathode of which is connected to the first terminal of the power inductor module.

3. The power conversion circuit according to claim 1, characterized in that, The power inductor module is the input winding of an isolation transformer.

4. The power conversion circuit according to any one of claims 1-3, characterized in that, It also includes a control chip, the output pin of which is connected to the second end of the power inductor module.

5. The power conversion circuit according to any one of claims 1-3, characterized in that, The inductance between the third terminal and the second terminal in the power inductor module is equal to one-tenth to one-half of the inductance between the first terminal and the second terminal.

6. The power conversion circuit according to claim 5, characterized in that, In the power inductor module, the inductance between the third terminal and the second terminal is equal to one-quarter of the inductance between the first terminal and the second terminal.

7. The power conversion circuit according to any one of claims 1-3, characterized in that, The inductance of the first inductor is 1 to 10 times the inductance of the power inductor module.

8. The power conversion circuit according to claim 7, characterized in that, The inductance of the first inductor is twice the inductance of the power inductor module.

9. A lighting device, characterized in that, Its driving circuit includes the power conversion circuit as described in any one of claims 1-8.

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