CN219351552U

CN219351552U - Control circuit of passive PFC circuit converter

Info

Publication number: CN219351552U
Application number: CN202223332334.8U
Authority: CN
Inventors: 肖俊承; 王一龙; 石从怀; 田卫红; 廖日云
Original assignee: Foshan Yigeer Electronics Co ltd; Eaglerise Electric and Electronic China Co Ltd; Foshan Shunde Eaglerise Electric Power Technology Co Ltd; Jian Eaglerise Electric Co Ltd; Jian Eaglerise Magnetic Technology Co Ltd; Jiangxi Eaglerise Digital Energy Technology Co Ltd
Current assignee: Foshan Yigeer Electronics Co ltd; Eaglerise Electric and Electronic China Co Ltd; Foshan Shunde Eaglerise Electric Power Technology Co Ltd; Jian Eaglerise Electric Co Ltd; Jian Eaglerise Magnetic Technology Co Ltd; Jiangxi Eaglerise Digital Energy Technology Co Ltd
Priority date: 2022-12-13
Filing date: 2022-12-13
Publication date: 2023-07-14
Anticipated expiration: 2032-12-13

Abstract

The utility model relates to the technical field of circuit converters, in particular to a control circuit of a passive PFC circuit converter, which comprises a bridge rectifier unit, a harmonic wave improving unit and an isolation flyback unit, wherein the input end of the harmonic wave improving unit is electrically connected with the direct current output end of the bridge rectifier unit, the output end of the harmonic wave improving unit is electrically connected with the input end of the isolation flyback unit, and the harmonic wave improving unit comprises a diode D1, a diode D2, a nonpolar capacitor CB1, an inductor L1 and a polar capacitor EC1; the isolation flyback unit comprises an input module, a transformer T1, an output module, a drive control module and an output current control module, wherein the drive control module comprises a drive chip IC1, and the model of the drive chip IC1 is OB5682; the utility model has simple circuit and low cost, has the effects of improving the power factor and reducing the switching loss, and has better performance than the traditional passive PFC under the same condition.

Description

Control circuit of passive PFC circuit converter

Technical Field

The utility model relates to the technical field of circuit converters, in particular to a control circuit of a passive PFC circuit converter.

Background

In the application field of the existing low-end low-power supply, the traditional circuit design is generally adopted due to the fact that the requirements on cost are too strict, so that the efficiency is low, the power factor is low, and the cost and the performance cannot be kept moderate. Therefore, in order to reduce pollution of the ac power grid by the harmonic wave, related standards for limiting the current harmonic wave are formulated at home and abroad, which also makes the Power Factor Correction (PFC) technology a research hot spot in the power electronics field.

In the application field of PFC technology, active PFC and passive PFC are classified. Among the advantages of active PFC are its wide voltage range and high power factor, which is mainly used in some medium-high-end power supply fields, and therefore its cost is relatively high. The power factor of the passive PFC is not very high, but generally only can reach 0.7-0.8, and the efficiency is lower than that of a power supply with an active PFC circuit structure. In fact, active PFC is due to its complexity of circuit structure, resulting in its own increased loss and large electromagnetic interference generated by its boost circuit, so that at low power, active PFC itself may be more lossy than passive PFC. At present, active PFC circuits are widely applied in the field of high-end products, and traditional passive PFC circuits are mainly applied in the field of low-end power supplies due to simple circuit structure and low cost.

The traditional passive PFC is applied to the field of LED power supply driving, for example, because IEC61000-3-2 standard is updated, the harmonic current limit value of a drive with the power level of 5WLED is required, a series of circuits for solving the harmonic current are required to be produced, for example, the PF value of the traditional passive PFC-valley filling circuit PFC can be improved to 0.8-0.9, but the defects are that the THD value is larger, the power loss is not low, the aluminum electrolysis capacity after rectification is required to be small, and the harmonic wave is not good in light load; and the boost PFC circuit is complex and has high cost.

Disclosure of Invention

The utility model aims to provide a control circuit of a passive PFC circuit converter, which has the advantages of simple circuit and low cost, solves the problems of low PF value, low efficiency, larger THD and high application cost of an active PFC circuit in the prior art, has the effects of improving the power factor and reducing the switching loss, and has better performance than the traditional passive PFC under the same condition.

To achieve the purpose, the utility model adopts the following technical scheme:

the control circuit of the passive PFC circuit converter comprises a bridge rectifier unit, a harmonic wave improving unit and an isolation flyback unit, wherein the input end of the harmonic wave improving unit is electrically connected with the direct current output end of the bridge rectifier unit, and the output end of the harmonic wave improving unit is electrically connected with the input end of the isolation flyback unit;

the harmonic improving unit comprises a diode D1, a diode D2, a nonpolar capacitor CB1, an inductor L1 and a polar capacitor EC1;

the isolation flyback unit comprises an input module, a transformer T1, an output module, a drive control module and an output current control module, wherein the drive control module comprises a drive chip IC1, and the model of the drive chip IC1 is OB5682;

the positive electrode of the diode D1, the positive electrode of the diode D2, the HV end of the driving chip IC1 and one end of the nonpolar capacitor CB1 are all electrically connected with the direct current output end of the bridge rectifier unit, the negative electrode of the diode D1 and the positive electrode of the polar capacitor EC1 are all electrically connected with the non-homonymous end of the primary winding of the transformer T1, the negative electrode of the diode D2 is electrically connected with one end of the inductor L1, the other end of the inductor L1 and the DRAIN end of the driving chip IC1 are all electrically connected with the homonymous end of the primary winding of the transformer T1, and the other end of the nonpolar capacitor CB1 and the negative electrode of the polar capacitor EC1 are all grounded;

the input module is electrically connected with the primary winding of the transformer T1;

the output module is electrically connected with the secondary winding of the transformer T1;

one end of the output current control module is electrically connected with the CS end of the driving chip IC1, and the other end of the output current control module is grounded.

Preferably, the input module includes a resistor R4, a resistor R5, a resistor R8, a resistor R9, a non-polar capacitor C1, and a diode D3;

one end of the resistor R4, one end of the resistor R5 and one end of the nonpolar capacitor C1 are electrically connected with the non-homonymous end of the primary winding of the transformer T1, and the other end of the resistor R4, the other end of the resistor R5, one end of the resistor R8 and the other end of the nonpolar capacitor C1 are electrically connected with one end of the resistor R9;

the other end of the resistor R8 and the other end of the resistor R9 are electrically connected with the negative electrode of the diode D3, and the positive electrode of the diode D3 is electrically connected with the homonymous end of the primary winding of the transformer T1.

Preferably, the output module includes a non-polar capacitor C3, a resistor R11, a diode D4, a polar capacitor EC2, and a resistor R12A;

one end of the nonpolar capacitor C3, the positive electrode of the diode D4 and the same name end of the secondary winding of the transformer T1 are electrically connected, the other end of the nonpolar capacitor C3 and one end of the resistor R11 are electrically connected, the other end of the resistor R11, the positive electrode of the polar capacitor EC2 and one end of the resistor R12A are electrically connected to the negative electrode of the diode D4, and the negative electrode of the polar capacitor EC2, the other end of the resistor R12A and the non-same name end of the secondary winding of the transformer T1 are connected with the SGND end;

the same-name ground of the auxiliary winding of the transformer T1 is grounded.

Preferably, the driving control module further comprises a resistor R6 and a resistor R7;

one end of the resistor R6 and one end of the resistor R7 are electrically connected with the OVP end of the driving chip IC1, and the other end of the resistor R6 and the other end of the resistor R7 are grounded.

Preferably, the output current control module includes a resistor R9A, a resistor R9B, and a resistor R910;

one end of the resistor R9A, one end of the resistor R9B and one end of the resistor R910 are electrically connected with the CS end of the driving chip IC1, and the other end of the resistor R9A, the other end of the resistor R9B and the other end of the resistor R910 are grounded.

Preferably, the output module further includes a non-polar capacitor CY1 and a non-polar capacitor CY2, one end of the non-polar capacitor CY1 is electrically connected with the same-name end of the primary winding of the transformer T1, the other end of the non-polar capacitor CY1 is electrically connected with the positive electrode of the polar capacitor EC2, one end of the non-polar capacitor CY2 is grounded, and the other end of the non-polar capacitor CY2 is connected with the SGND end.

Preferably, the bridge rectifier unit includes a rectifier bridge DB1 and a fuse F1;

one end of the fuse F1 is electrically connected with a mains supply fire wire, the other end of the fuse F1 is electrically connected with a first input end of the rectifier bridge DB1, a second input end of the rectifier bridge DB1 is electrically connected with a mains supply zero wire, a direct current output positive electrode of the rectifier bridge DB1 is a direct current output end of the bridge rectifier unit, and a direct current output negative electrode of the rectifier bridge DB1 is grounded.

One of the above technical solutions has the following beneficial effects: the circuit is simple, the cost is low, the loss is lower than that of the traditional passive PFC/valley filling circuit, the converter efficiency can reach about 87%, the harmonic wave is good, the THD value is less than 15%, the PF value is more than 0.90, and the circuit has very good cost compared with a boost PFC circuit.

Drawings

Fig. 1 is a schematic diagram of a control circuit of a passive PFC circuit converter according to the present utility model;

fig. 2 is a schematic diagram of a current trend of a control circuit of a passive PFC circuit converter according to the present utility model;

in the accompanying drawings: the bridge rectifier comprises a bridge rectifier unit 1, a harmonic wave improving unit 2, an isolation flyback unit 3, an input module 31, an output module 32, a driving control module 33 and an output current control module 34.

Detailed Description

The technical scheme of the utility model is further described below by the specific embodiments with reference to the accompanying drawings.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element in question must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present utility model, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

As shown in fig. 1-2, a control circuit of a passive PFC circuit converter includes a bridge rectifier unit 1, a harmonic improving unit 2, and an isolated flyback unit 3, wherein an input end of the harmonic improving unit 2 is electrically connected with a dc output end of the bridge rectifier unit 1, and an output end of the harmonic improving unit 2 is electrically connected with an input end of the isolated flyback unit 3;

the harmonic improving unit 2 includes a diode D1, a diode D2, a non-polar capacitance CB1, an inductor L1, and a polar capacitance EC1;

the isolation flyback unit 3 comprises an input module 31, a transformer T1, an output module 32, a drive control module 33 and an output current control module 34, wherein the drive control module 33 comprises a drive chip IC1, and the model of the drive chip IC1 is OB5682;

the positive electrode of the diode D1, the positive electrode of the diode D2, the HV end of the driving chip IC1 and one end of the nonpolar capacitor CB1 are electrically connected with the direct current output end of the bridge rectifier unit 1, the negative electrode of the diode D1 and the positive electrode of the polar capacitor EC1 are electrically connected with the non-homonymous end of the primary winding of the transformer T1, the negative electrode of the diode D2 is electrically connected with one end of the inductor L1, the other end of the inductor L1 and the DRAIN end of the driving chip IC1 are electrically connected with the homonymous end of the primary winding of the transformer T1, and the other end of the nonpolar capacitor CB1 and the negative electrode of the polar capacitor EC1 are grounded;

the input module 31 is electrically connected with the primary winding of the transformer T1;

the output module 32 is electrically connected with the secondary winding of the transformer T1;

one end of the output current control module 34 is electrically connected to the CS end of the driving chip IC1, and the other end of the output current control module 34 is grounded.

In order to improve the technical scheme adopted by the traditional passive PFC circuit, the control circuit of the passive PFC circuit converter is provided, and comprises a bridge rectifier unit 1, a harmonic wave improving unit 2 and an isolation flyback unit 3, wherein the bridge rectifier unit 1 is used for converting supplied commercial power into direct current through a rectifier bridge, the harmonic wave improving unit 2 is used for carrying out harmonic wave filtering processing on input, and the isolation flyback unit 3 is used for providing an output power supply for an output module 32 for load through a transformer T1 with an isolation function.

The working principle of the harmonic wave improving unit 2 is that when a built-in MOS (or SW) of a driving chip IC1 is conducted, alternating current at the input end of a bridge rectifier unit 1 is sine wave, and after being rectified and filtered by the bridge rectifier unit 1, one path of alternating current passes through a diode D1, so that a primary winding of a transformer T1 stores energy; one path passes through a diode D2 to enable an inductor L1 to store energy, and then passes through a D-S pole of a built-in MOS tube of a driving chip IC1 and an output current control module 34 to return to the rectified ground, wherein the current trend is shown as a route A in FIG. 2; when the amplitude of the direct current output voltage of the bridge rectifier unit 1 is increased and is larger than the voltage of the polarity capacitor EC1, one path of direct current output voltage passes through the diode D1 to charge the polarity capacitor EC 1.

When the built-in MOS tube (or SW) of the driving chip IC1 is disconnected, the alternating current at the input end of the bridge rectifier unit 1 is sine wave, the alternating current is converted into direct current through the bridge rectifier unit 1, the bridge rectifier unit 1 outputs direct current, the direct current passes through the diode D2 and the inductor L1 again, the inductor L1 releases energy at the moment, the primary winding of the transformer T1 charges the polar capacitor EC1 again, and the current trend is shown as a route B in FIG. 2;

to sum up, the present application provides a direct energy transfer path for supplying energy to an output load by connecting an inductor L1 and a diode D2 in series to the primary winding of a flyback transformer T1. Meanwhile, since the inductor L1 is always connected in series with the primary winding of the transformer T1. Therefore, no matter whether the built-in MOS tube (or SW) of the driving chip IC1 is on or off, the inductance current volt-second balance of the inductor L1 can still enable the polarity capacitor EC1 of the energy storage filter to realize voltage level stabilization under the condition of obviously reducing, and the voltage between two ends of the polarity capacitor EC1 can be limited to a desired level, so that the conversion efficiency is improved. For example, a regulated voltage of 400V may be achieved over the universal input range of 90-264V.

The characteristic of the voltage lead current of the inductor L1 also compensates for phase distortion caused by capacitive load, so that the power factor, electromagnetic compatibility and electromagnetic interference are improved. This is because inductor L1 is typically designed to operate in Discontinuous Conduction Mode (DCM). Therefore, under DCM operation, since the DCM boost converter remains relatively constant for half a line period, a nearly sinusoidal current is generated, thereby achieving low input current harmonic distortion and increasing the PF value. At this time, if the inductor L1 exceeds the maximum value of its DCM operation, the inductor L1 operates in a Continuous Conduction Mode (CCM) at a narrow interval near the peak of the rectified line voltage. In general, the larger inductance of inductor L1 may increase converter efficiency and reduce input current ripple. Furthermore, if a variable switching frequency control circuit is used (i.e. driver chip IC1 control), flyback transformer T1 may be operated at DCM, CCM or DCM/CCM boundary. By operating in DCM/CCM boundary mode, the transformer T1 can greatly reduce switching losses. Thus, the disadvantages of conventional passive PFCs can be overcome as long as the design parameters are appropriate.

In summary, in order to overcome the defects that the power factor interval range of the traditional passive PFC can only be at most 0.7-0.8, the total harmonic distortion is larger and the loss is larger, the application provides a control circuit of the passive PFC circuit converter, which can improve the power factor interval range and reduce the switching loss, and the scheme can improve the PF value to the interval of 0.8-0.9 and even be larger than 0.9, so that the total harmonic distortion is smaller than that of the traditional passive PFC. The circuit is simple, the cost is low, the loss is lower than that of a traditional passive PFC/valley filling circuit, the converter efficiency can reach about 87%, the harmonic wave is good, the THD value is less than 15%, the PF value is more than 0.90, and the circuit is very advantageous in cost compared with a boost PFC circuit.

To illustrate further, the input module 31 includes a resistor R4, a resistor R5, a resistor R8, a resistor R9, a non-polar capacitor C1, and a diode D3;

In the present embodiment, by providing the polar diode D3 in the input module 31, the conduction loss of the transformer T1 in the primary winding in the flyback converter is greatly reduced. In addition, the effective current between the energy storage inductor L1 and diode D3 is staggered around the peak of the rectified line voltage, thereby significantly reducing input current ripple and reducing current stress on the switch, reducing circuit losses.

To further illustrate, the output module 32 includes a non-polar capacitor C3, a resistor R11, a diode D4, a polar capacitor EC2, and a resistor R12A;

In this embodiment, the positive electrode and the negative electrode of the polar capacitor EC2 are output ends of the output module 32. The rectifier diode D4 rectifies the current of the secondary winding of the transformer T1 and outputs the rectified current to the load. The polar capacitor EC2 starts the filtering function, so that the output current is smooth, and the effect of constant current output is achieved.

To illustrate further, the drive control module 33 further includes a resistor R6 and a resistor R7;

In this embodiment, in the output module 32, when a current flows through the resistors R6 and R7, corresponding voltages are generated, and after the voltage exceeds a certain value, a signal is sent to turn off the driving chip IC1, so as to protect the subsequent circuit. And the damage of a post-stage circuit caused by overlarge input voltage is avoided.

To illustrate further, the output current control module 34 includes a resistor R9A, a resistor R9B, and a resistor R910;

In the present embodiment, in the output current control module 34, the resistor R9A, the resistor R9B and the resistor R910 generate corresponding voltages when current flows, and the voltages are provided to the driving chip IC1, because the turn ratio of the primary winding and the secondary winding of the transformer T1 is fixed, the LED driving chip U1 can control the output current through this signal.

To further illustrate, the output module 32 further includes a non-polar capacitor CY1 and a non-polar capacitor CY2, wherein one end of the non-polar capacitor CY1 is electrically connected to the same-name end of the primary winding of the transformer T1, the other end of the non-polar capacitor CY1 is electrically connected to the positive electrode of the polar capacitor EC2, one end of the non-polar capacitor CY2 is grounded, and the other end of the non-polar capacitor CY2 is connected to the SGND end.

To illustrate further, the bridge rectifier unit 1 includes a rectifier bridge DB1 and a fuse F1;

one end of the fuse F1 is electrically connected with a mains supply fire wire, the other end of the fuse F1 is electrically connected with a first input end of the rectifier bridge DB1, a second input end of the rectifier bridge DB1 is electrically connected with a mains supply zero wire, a direct current output positive electrode of the rectifier bridge DB1 is a direct current output end of the bridge rectifier unit 1, and a direct current output negative electrode of the rectifier bridge DB1 is grounded.

In this embodiment, the fuse F1 in the bridge rectifier unit 1 plays an over-current protection role on the control circuit of the whole passive PFC circuit converter; the rectifier bridge DB1 converts the supplied mains power into direct current for use by the isolated flyback unit 3.

The technical principle of the present utility model is described above in connection with the specific embodiments. The description is made for the purpose of illustrating the general principles of the utility model and should not be taken in any way as limiting the scope of the utility model. Other embodiments of the utility model will occur to those skilled in the art from consideration of this specification without the exercise of inventive faculty, and such equivalent modifications and alternatives are intended to be included within the scope of the utility model as defined in the claims.

Claims

1. The control circuit of the passive PFC circuit converter is characterized by comprising a bridge rectifier unit, a harmonic wave improving unit and an isolation flyback unit, wherein the input end of the harmonic wave improving unit is electrically connected with the direct current output end of the bridge rectifier unit, and the output end of the harmonic wave improving unit is electrically connected with the input end of the isolation flyback unit, and the control circuit is characterized in that:

2. The control circuit of claim 1, wherein the input module comprises a resistor R4, a resistor R5, a resistor R8, a resistor R9, a non-polar capacitor C1, and a diode D3;

3. The control circuit of claim 2, wherein the output module comprises a non-polar capacitor C3, a resistor R11, a diode D4, a polar capacitor EC2, and a resistor R12A;

4. The control circuit of claim 3, wherein the drive control module further comprises a resistor R6 and a resistor R7;

5. The control circuit of claim 4, wherein the output current control module comprises a resistor R9A, a resistor R9B, and a resistor R910;

6. The control circuit of claim 3, wherein the output module further comprises a non-polar capacitor CY1 and a non-polar capacitor CY2, one end of the non-polar capacitor CY1 is electrically connected to a homonymous end of the primary winding of the transformer T1, the other end of the non-polar capacitor CY1 is electrically connected to the positive electrode of the polar capacitor EC2, one end of the non-polar capacitor CY2 is grounded, and the other end of the non-polar capacitor CY2 is connected to the SGND end.

7. The control circuit of claim 1, wherein the bridge rectifier unit comprises a rectifier bridge DB1 and a fuse F1;