A driving circuit, device and driving method for suppressing electromagnetic interference

Abstract

The present invention discloses a driving circuit, a device and a driving method for suppressing electromagnetic interference. The driving circuit for suppressing electromagnetic interference comprises a rectifier module, a constant current source module, an energy storage module, a switching power supply module and a load. The input alternating current is rectified by the rectifier module and then outputs a line voltage to the energy storage module and the switching power supply module. The energy storage module is used to store electric energy when the line voltage is greater than the charging voltage of the energy storage module, and to supply power to the switching power supply module and the load when the line voltage is less than the charging voltage. The switching power supply module is used to convert the line voltage into low-voltage direct current and output it to the load. The constant current source module is used to adjust the charging current when the energy storage module stores electric energy and control the charging time of the energy storage module. The electromagnetic interference in the circuit is suppressed, the harmonic noise in the circuit is reduced and the power factor is improved through a simple circuit structure.

Description

Technical Field

[0001] The present invention relates to the technical field of LED driving, and in particular to a driving circuit, a device and a driving method for suppressing electromagnetic interference. Background Art

[0002] In LED applications, the switching power supply has two functions: one is to convert the high-voltage power supply into a low-voltage DC power supply to power the dimmer in the dimming LED lamp, and the other is to directly drive the LED lamp string to emit light after the high-voltage power supply is converted. Both require a high-voltage electrolytic filter capacitor to be connected after the rectifier bridge to obtain a DC voltage with a relatively flat waveform. Although the input is a sinusoidal AC voltage, the current waveform obtained after rectification and filtering is severely distorted and pulse-shaped. The pulse-shaped input current contains a large number of harmonic components, which increases the harmonic noise level and reduces the power factor at the input end. The switching power supply controls the output voltage and current by changing the conduction ratio of the switching device. When the switching device is turned on or off, a sudden change in current is generated in the circuit, forming a strong electromagnetic interference. If the interference enters the interfered body, it will affect its normal operation.

[0003] Therefore the prior art still needs to be improved and enhanced. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a driving circuit, device and driving method for suppressing electromagnetic interference, which can suppress the electromagnetic interference caused by the charging current of the electrolytic capacitor and the conduction or disconnection of the switching power supply in the circuit through a simple circuit structure, reduce the harmonic noise in the circuit, and improve the power factor.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A driving circuit for suppressing electromagnetic interference comprises a rectifier module, a constant current source module, an energy storage module, a switching power supply module and a load; input alternating current is rectified by the rectifier module and then outputs a line voltage to the energy storage module and the switching power supply module; the energy storage module is used to store electric energy when the line voltage is greater than the charging voltage of the energy storage module, and to supply power to the switching power supply module and the load when the line voltage is less than the charging voltage; the switching power supply module is used to convert the line voltage into low-voltage direct current and output it to the load; the constant current source module is used to adjust the charging current when the energy storage module stores electric energy, and control the charging time of the energy storage module.

[0007] In the driving circuit for suppressing electromagnetic interference, the switching power supply module includes a first constant voltage chip, a first diode, a first resistor, a second resistor, a first capacitor, a second capacitor and a first inductor, the first pin of the first constant voltage chip is connected to the cathode of the first diode, one end of the first resistor and one end of the first inductor through the second capacitor, the second pin of the first constant voltage chip is connected to the other end of the first resistor and one end of the second resistor, the 8th pin, the 7th pin, the 6th pin and the 5th pin of the first constant voltage chip are all connected to the cathode of the first diode, the anode of the first diode and one end of the first capacitor are grounded, the other end of the first capacitor, the other end of the second resistor and one end of the first inductor are all VDD signal ends; the 4th pin of the first constant voltage chip is connected to the VIN signal end.

[0008] In the driving circuit for suppressing electromagnetic interference, the switching power supply module includes a second diode, a third capacitor, a second constant voltage chip, a third resistor and a second inductor; the positive electrode of the second diode is connected to one end of the second inductor and the first pin of the second constant voltage chip, the negative electrode of the second diode is connected to the energy storage module, the constant current source module, the input end of the load and one end of the third capacitor, and the other end of the third capacitor is connected to the other end of the second inductor and the output end of the load; one end of the third resistor is grounded, the other end of the third resistor is connected to the second pin of the second constant voltage chip, and the 5th pin of the second constant voltage chip is connected to the input end of the load.

[0009] In the driving circuit for suppressing electromagnetic interference, the constant current source module includes a first operational amplifier, a first MOS tube and a fourth resistor; the drain of the first MOS tube is connected to the rectifier module, the source of the first MOS tube is connected to the inverting input terminal of the first operational amplifier and one end of the fourth resistor, the other end of the fourth resistor is connected to the energy storage module, the switching power supply module and the input terminal of the load, and the gate of the first MOS tube is connected to the output terminal of the first operational amplifier.

[0010] In the driving circuit for suppressing electromagnetic interference, the constant current source module includes a second MOS tube, a second operational amplifier and a fifth resistor; the drain of the second MOS tube is connected to the energy storage module, the switching power supply module and the load, the source of the second MOS tube is connected to one end of the fifth resistor and the inverting input end of the second operational amplifier, the gate of the second MOS tube is connected to the output end of the second operational amplifier, and the other end of the fifth resistor is connected to the rectifier module.

[0011] In the driving circuit for suppressing electromagnetic interference, the energy storage module includes a fourth capacitor, one end of the fourth capacitor is connected to the other end of the fourth resistor, and the other end of the fourth capacitor is grounded.

[0012] In the driving circuit for suppressing electromagnetic interference, the energy storage module includes a fifth capacitor, one end of the fifth capacitor is connected to the drain of the second MOS tube, and the other end of the fifth capacitor is connected to the rectifier module.

[0013] In the driving circuit for suppressing electromagnetic interference, the load includes a third diode, an LED light string, a dimmer, a third operational amplifier, a third MOS tube and a sixth resistor; the positive electrode of the third diode is connected to one end of the fourth capacitor, the other end of the fourth resistor and the fourth pin of the first constant voltage chip; the negative electrode of the third diode is connected to the input end of the LED light string, the drain of the third MOS tube is connected to the output end of the LED light string, the source of the third MOS tube is connected to one end of the sixth resistor and the inverting input end of the third operational amplifier, the output end of the third operational amplifier is connected to the gate of the third MOS tube, the non-inverting input end of the third operational amplifier is connected to the third pin of the dimmer, the second pin of the dimmer is grounded, and the first pin of the dimmer is connected to the switching power supply module.

[0014] A driving method based on the driving circuit for suppressing electromagnetic interference as described above comprises the following steps:

[0015] The input AC power is rectified by the rectifier module and then outputs the line voltage to the energy storage module and the switching power supply module;

[0016] When the line voltage is greater than the charging voltage of the energy storage module, the energy storage module stores electric energy, and when the line voltage is less than the charging voltage, the energy storage module supplies power to the load;

[0017] The switching power supply module converts the line voltage into low-voltage direct current and outputs it to the load;

[0018] When the energy storage module stores electric energy, the constant current source module adjusts the charging current so that the charging time of the energy storage module is increased.

[0019] A driving device for suppressing electromagnetic interference comprises a shell, a PCB board is arranged in the shell, and the driving circuit for suppressing electromagnetic interference as described above is arranged on the PCB board.

[0020] Compared with the prior art, the present invention provides a driving circuit, device and driving method for suppressing electromagnetic interference. The driving circuit for suppressing electromagnetic interference includes a rectifier module, a constant current source module, an energy storage module, a switching power supply module and a load; the input alternating current is rectified by the rectifier module and then outputs a line voltage to the energy storage module and the switching power supply module; the energy storage module is used to store electric energy when the line voltage is greater than the charging voltage of the energy storage module, and to supply power to the switching power supply module and the load when the line voltage is less than the charging voltage; the switching power supply module is used to convert the line voltage into low-voltage direct current and output it to the load; the constant current source module is used to adjust the charging current when the energy storage module stores electric energy, and control the charging time of the energy storage module, so that the electromagnetic interference in the circuit is suppressed, the harmonic noise in the circuit is reduced, and the power factor is improved through a simple circuit structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A circuit block diagram of a driving circuit for suppressing electromagnetic interference provided by the present invention;

[0022] Figure 2 A circuit schematic diagram of a switching power supply module in the first embodiment and the second embodiment of the driving circuit for suppressing electromagnetic interference provided by the present invention;

[0023] Figure 3 A circuit schematic diagram of a first embodiment of a driving circuit for suppressing electromagnetic interference provided by the present invention;

[0024] Figure 4 A circuit schematic diagram of a second embodiment of a driving circuit for suppressing electromagnetic interference provided by the present invention;

[0025] Figure 5 A circuit schematic diagram of a dimmer in the first embodiment and the second embodiment of the driving circuit for suppressing electromagnetic interference provided by the present invention;

[0026] Figure 6 A circuit schematic diagram of a third embodiment of a driving circuit for suppressing electromagnetic interference provided by the present invention;

[0027] Figure 7 A flow chart of the steps of a driving method for a driving circuit for suppressing electromagnetic interference provided by the present invention. DETAILED DESCRIPTION

[0028] The purpose of the present invention is to provide a driving circuit, device and driving method for suppressing electromagnetic interference, which can suppress the electromagnetic interference caused by the charging current of the electrolytic capacitor and the conduction or disconnection of the switching power supply in the circuit through a simple circuit structure, reduce the harmonic noise in the circuit, and improve the power factor.

[0029] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] See also Figure 1 The electromagnetic interference suppression driving circuit provided by the present invention comprises a rectifier module 100, a constant current source module 200, an energy storage module 300, a switching power supply module 400 and a load 500, wherein the constant current source module 200 is connected to the output end of the rectifier module 100, and the constant current source module 200 is also connected to the energy storage module 300, the switching power supply module 400 and the load 500, the energy storage module 300 is also connected to the load 500 and the switching power supply module 400, and the switching power supply module 400 is also connected to the load 500.

[0031] The input AC power is rectified by the rectifier module 100 and then outputs a line voltage to the energy storage module 300 and the switching power supply module 400; the energy storage module 300 is used to store electric energy when the line voltage is greater than the charging voltage of the energy storage module 300, and to supply power to the switching power supply module 400 and the load 500 when the line voltage is less than the charging voltage; the switching power supply module 400 is used to convert the line voltage into low-voltage DC power and output it to the load 500; the constant current source module 200 is used to adjust the charging current when the energy storage module 300 stores electric energy, control the charging time of the energy storage module 300, and thereby suppress electromagnetic interference in the circuit.

[0032] The rectifier module 100 includes a rectifier bridge. It should be noted that the rectifier bridge is a prior art, and the specific structure of the rectifier bridge is not described in detail here. The rectifier bridge rectifies the alternating current and outputs the line voltage to the energy storage module 300 and the switching power supply module 400 through the constant current source module 200. When the line voltage is greater than the charging voltage of the energy storage module 300, the charging current of the energy storage module 300 is controlled by the constant current source module 200 to charge the energy storage module 300 to store electrical energy. When the line voltage is less than the charging voltage of the energy storage module 300, the energy storage module 300 The switching power supply module 400 is discharged; during the charging process of the energy storage module 300, the current passing through the rectifier bridge is the current set by the constant current source module 200, and the constant current source module 200 adjusts the charging current of the energy storage module 300 to be slower by setting a smaller current, and the charging time of the energy storage module 300 is prolonged; and during the discharging process of the energy storage module 300, no current flows through the rectifier bridge, so that the current mutation of the switching power supply module 400 is controlled and the electromagnetic interference is suppressed. Because the charging current of the capacitor is slower and the charging time is longer, the harmonic noise is also suppressed and the power factor is improved.

[0033] For specific implementation, please refer to Figure 2 In the first embodiment of the present invention, the switching power supply module 400 includes a first constant voltage chip U1, a first diode D1, a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2 and a first inductor L1, the first pin of the first constant voltage chip U1 is connected to the cathode of the first diode D1, one end of the first resistor R1 and one end of the first inductor L1 through the second capacitor C2, the second pin of the first constant voltage chip U1 is connected to the other end of the first resistor R1 and one end of the second resistor R2, the 8th pin, the 7th pin, the 6th pin and the 5th pin of the first constant voltage chip U1 are all connected to the cathode of the first diode D1, the anode of the first diode D1 and the first capacitor C2 are connected to the cathode of the first inductor L1, and the cathode of the first inductor L1 is connected to the cathode of the first inductor L1. 1 is grounded, and the other ends of the first capacitor C1, the other ends of the second resistor R2 and one end of the first inductor L1 are all VDD signal ends; the 4th pin of the first constant voltage chip U1 is connected to the VIN signal end, and the energy storage module 300 provides power for the operation of the switching power supply module 400 when discharging, so as to ensure the stable operation of the switching power supply module 400, that is, the switching power supply module 400 converts the line voltage into low-voltage direct current to supply power to the load 500, so as to ensure the normal operation of the load 500; in this embodiment, the model of the first constant voltage chip U1 is BP8516F, and of course, a constant voltage chip with the same function can also be used in other embodiments, and the present invention is not limited to this.

[0034] For further information, please also refer to Figure 3 In this embodiment, the constant current source module 200 includes a first operational amplifier OP1, a first MOS tube Q1 and a fourth resistor R4; the drain of the first MOS tube Q1 is connected to the rectifier module 100, the source of the first MOS tube Q1 is connected to the inverting input terminal of the first operational amplifier OP1 and one end of the fourth resistor R4, the other end of the fourth resistor R4 is connected to the input terminals of the energy storage module 300, the switching power supply module 400 and the load 500, the gate of the first MOS tube Q1 is connected to the output terminal of the first operational amplifier OP1, wherein the fourth resistor R 4 is a constant current resistor, and the charging current of the energy storage module 300 is adjusted by changing the resistance value of the fourth resistor R4; the non-phase input terminal of the first operational amplifier OP1 is connected to the reference voltage Vref input terminal to obtain the reference voltage Vref. When the reference voltage Vref is fixed, the charging current of the energy storage module 300 is constant; when the reference voltage Vref changes with the phase of the AC power, as the line voltage increases, the voltage value of the reference voltage Vref increases, and the charging current of the energy storage module 300 increases. Compared with the case where the charging current is constant, the power factor is higher.

[0035] Furthermore, in the present embodiment, the energy storage module 300 includes a fourth capacitor C4, one end of the fourth capacitor C4 is connected to the other end of the fourth resistor R4, and the other end of the fourth capacitor C4 is grounded, that is, in the first embodiment, the constant current source module 200 is connected to the input end of the energy storage module 300, and the fourth capacitor C4 is charged when the line voltage output by the rectifier bridge is greater than the charging voltage of the fourth capacitor C4, and when the line voltage output by the rectifier bridge is less than the charging voltage of the fourth capacitor C4, the first constant voltage chip U1 is discharged, thereby ensuring that the switching power supply module 400 can work stably.

[0036] Further, in order to adapt to the circuit structure in which the constant current source module 200 is connected to the output end of the rectifier bridge and the input end of the energy storage module 300, in this embodiment, the load 500 includes a third diode D3, an LED light string, a dimmer, a third operational amplifier OP3, a third MOS tube Q3 and a sixth resistor R6; the positive electrode of the third diode D3 is connected to one end of the fourth capacitor C4, the other end of the fourth resistor R4 and the fourth foot of the first constant voltage chip U1; the negative electrode of the third diode D3 is connected to the input end of the LED light string, the drain of the third MOS tube Q3 is connected to the output end of the LED light string, the source of the third MOS tube Q3 is connected to one end of the sixth resistor R6 and the inverting input end of the third operational amplifier OP3, and the third operational amplifier OP3 The output end of the third operational amplifier OP3 is connected to the gate of the third MOS tube Q3, the non-inverting input end of the third operational amplifier OP3 is connected to the third pin of the dimmer, the second pin of the dimmer is grounded, the first pin of the dimmer is connected to the switching power supply module 400, the third diode D3 is a discharge diode, when the fourth capacitor C4 is charged, the third diode D3 is reversely cut off, when the fourth capacitor C4 is discharged, the third diode D3 is turned on to discharge the LED light string; that is, in this embodiment, the fourth capacitor C4 can make the voltage across the LED light string always greater than the conduction voltage of the LED light string, so as to achieve the LED light string without flicker; on the other hand, the fourth capacitor C4 also provides stable power supply to the switching power supply module 400, so as to ensure the stable operation of the switching power supply module 400.

[0037] Among them, the third operational amplifier OP3, the third MOS tube Q3 and the sixth resistor R6 form a constant current source, which can realize the dimming of the LED light string according to the dimming signal output by the dimmer; specifically, when the switching power supply module 400 enters the working state, it provides low-voltage direct current to the dimmer, so that the dimmer outputs a dimming signal to the non-phase input terminal of the third operational amplifier OP3, and the third operational amplifier OP3 adjusts the working current of the LED light string according to the dimming signal, thereby realizing the dimming of the LED light string; and the reference voltage Vref in the constant current source module 200 can also be controlled by the dimming signal output by the dimmer. As the working current of the LED light string decreases, the charging current of the fourth capacitor C4 decreases accordingly, so that in the LED dimming application, a higher power factor and lower harmonic noise can be obtained when the brightness is lowered; in this embodiment, the dimming signal can be a voltage signal, a current signal or a PWM signal, and the present invention is not limited to this.

[0038] Specifically, in the first embodiment, the charge and discharge quantity Q of the fourth capacitor C4 satisfies: Q=I1*Tchg=I2*Tdis+Ibuck*Tdis, T=Tchg+Tdis, wherein T is the output pulse period of the rectifier bridge, Tchg is the charging time of the fourth capacitor C4, Tdis is the discharging time of the fourth capacitor C4, I1 is the charging current of the fourth capacitor C4, I2 is the current flowing through the LED light string, i.e., the working current, and Ibuck is the input current of the switching power supply module 400. When the fourth capacitor C4 is charged, the current Iac flowing through the rectifier bridge=I1+I2, because I1 and I2 are constant, Iac is also constant, and when the energy storage capacitor is discharged, Iac is 0, so that harmonic noise and electromagnetic interference are suppressed, and the power factor is improved.

[0039] In the second embodiment, see Figure 4 , the constant current source module 200 is connected to the output end of the energy storage module 300, and the input end of the energy storage module 300 is directly connected to the rectifier bridge; specifically, the constant current source module 200 includes a second MOS tube Q2, a second operational amplifier OP2 and a fifth resistor R5; the drain of the second MOS tube Q2 is connected to the energy storage module 300, the switching power supply module 400 and the load 500, the source of the second MOS tube Q2 is connected to one end of the fifth resistor R5 and the inverting input end of the second operational amplifier OP2, the gate of the second MOS tube Q2 is connected to the output end of the second operational amplifier OP2, and the other end of the fifth resistor R5 is connected to the rectifier module.

[0040] In this embodiment, what is different from the first embodiment is that the constant current source module 200 changes the charging current of the energy storage module 300 by adjusting the current Iac flowing through the rectifier bridge; wherein the fifth resistor R5 is a constant current resistor, and the current Iac flowing through the rectifier bridge is correspondingly changed by changing the resistance value of the fifth resistor R5; when the reference voltage Vref of the positive phase input of the second operational amplifier OP2 is fixed, the current Iac flowing through the rectifier bridge is constant; when the reference voltage Vref changes with the phase of the alternating current, as the line voltage increases, the voltage value of the reference voltage Vref increases, and the current Iac flowing through the rectifier bridge increases, and compared with the constant current Iac, the power factor is higher.

[0041] For further information, please refer to Figure 4The energy storage module 300 includes a fifth capacitor C5, one end of which is connected to the drain of the second MOS tube Q2, and the other end of which is connected to the rectifier module 100. The fifth capacitor C5 is charged when the line voltage output by the rectifier bridge is greater than the charging voltage of the fifth capacitor C5, and is discharged to the switching power supply module 400 when the line voltage output by the rectifier bridge is less than the charging voltage of the fifth capacitor C5, so as to ensure the stable operation of the switching power supply module 400.

[0042] Further, in order to adapt to the circuit connection structure of the constant current source module 200 and the energy storage module 300 in this embodiment, the load 500 includes a dimmer, an LED light string, a fourth MOS tube Q4, a fourth operational amplifier OP4 and a seventh resistor R7; similarly, the fourth MOS tube Q4, the fourth operational amplifier OP4 and the seventh resistor R7 form a constant current source, which can realize the dimming of the LED light string according to the dimming signal output by the dimmer; specifically, when the switching power supply module 400 enters the working state, it provides low-voltage direct current to the dimmer, so that The dimmer outputs a dimming signal to the non-inverting input terminal of the fourth operational amplifier OP4, and the fourth operational amplifier OP4 adjusts the operating current of the LED light string according to the dimming signal, thereby realizing dimming of the LED light string; and the reference voltage Vref in the constant current source module 200 can also be controlled by the dimming signal output by the dimmer. As the operating current of the LED light string decreases, the current Iac flowing through the rectifier bridge decreases accordingly, thereby ensuring that in LED dimming applications, a higher power factor and lower harmonic noise can be obtained when the brightness is lowered.

[0043] In this embodiment, the charge and discharge quantity Q of the fifth capacitor C5 satisfies Q=(I1-I2-Ibuck)*Tchg=I2*Tdis+Ibuck*T, T=Tchg+Tdis, T is the output pulse period of the rectifier bridge, Tchg is the capacitor charging time, Tdis is the capacitor discharging time, I1 is the charging current of the fifth capacitor C5, I2 is the current flowing through the LED light string, and Ibuck is the input current of the switching power supply module 400. When the fifth capacitor C5 is charged, the current Iac flowing through the rectifier bridge=I1, because I1 is constant, Iac is also constant, and when the energy storage capacitor is discharged, Iac is 0, so that harmonic noise and electromagnetic interference are suppressed, and the power factor is improved.

[0044] For further information, please also refer to Figure 5In the first and second embodiments, the dimmer includes a control chip U0, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11; the first pin of the control chip U0 is connected to the VDD signal end through the eighth resistor R8, the third pin of the control chip U0 is connected to the VDD signal end through the ninth resistor R9, the 12th pin of the control chip U0 is connected to the VDD signal end through the tenth resistor R10, and the 10th pin of the control chip U0 is grounded through the eleventh resistor R11. After the switching power supply module 400 is powered and enters the working state, the control chip U0 outputs the dimming signal to the positive phase input end of the third operational amplifier OP3 or the positive phase input end of the fourth operational amplifier OP4 through the 14th pin of the control chip U0, thereby realizing the dimming of the LED light string; the model of the control chip U0 is ESP-12F. Of course, a control chip U0 with the same function can also be used in other embodiments, and the present invention is not limited to this.

[0045] For further information, see Figure 6 In the third embodiment, the constant current source module 200 is connected to the output end of the rectifier bridge and the input end of the energy storage module 300. Since this connection method is described in detail in the first embodiment, it will not be repeated here.

[0046] In this embodiment, the switching power supply module 400 includes a second diode D2, a third capacitor C3, a second constant voltage chip U2, a third resistor R3 and a second inductor L2; the anode of the second diode D2 is connected to one end of the second inductor L2 and the first pin of the second constant voltage chip U2 of the second constant voltage chip U2, the cathode of the second diode D2 is connected to the energy storage module 300, the constant current source module 200, the input end of the load 500 and one end of the third capacitor C3, the other end of the third capacitor C3 is connected to the other end of the second inductor L2 and the The output end of the load 500; one end of the third resistor R3 is grounded, the other end of the third resistor R3 is connected to the 2nd pin of the second constant voltage chip U2, and the 5th pin of the second constant voltage chip U2 is connected to the input end of the load 500, wherein the second diode D2 is a freewheeling diode, the third capacitor C3 is an electrolytic capacitor, and the third resistor R3 is a constant current resistor. In this embodiment, the model of the second constant voltage chip U2 is BP2865S. Of course, in other embodiments, a constant voltage chip with the same function may also be used, and the present invention is not limited to this.

[0047] In this embodiment, the load 500 includes an LED light string. Similarly, the constant current source module 200 in this embodiment changes the charging current of the fourth capacitor C4 by changing the resistance value of the fourth resistor R4. When the reference voltage Vref is fixed, the charging current of the fourth capacitor C4 is constant; when the reference voltage Vref changes with the phase of the AC power, as the line voltage increases, the voltage value of the reference voltage Vref increases, and the charging current of the fourth capacitor C4 increases. Compared with the constant charging current, the power factor is higher.

[0048] In this embodiment, the charge and discharge quantity Q of the fourth capacitor C4 satisfies: Q=I1*Tchg=Ibuck*Tdis, T=Tchg+Tdis, T is the output pulse period of the rectifier bridge, Tchg is the capacitor charging time, Tdis is the discharge time of the fourth capacitor C4, I1 is the charging current of the fourth capacitor C4, and Ibuck is the input current of the switch unit module. When the fourth capacitor C4 is charged, the current Iac flowing through the rectifier bridge is I1, because I1 is constant, Iac is also constant, and when the fourth capacitor C4 is discharged, Iac is 0, so that harmonic noise and electromagnetic interference are suppressed, and the power factor is improved.

[0049] Accordingly, the present invention also provides a dimming method for a driving circuit for suppressing electromagnetic interference, such as Figure 7 As shown, it includes the following steps:

[0050] S100, the input AC power is rectified by the rectifier module and then outputs a line voltage to the energy storage module and the switching power supply module;

[0051] S200, when the line voltage is greater than the charging voltage of the energy storage module, the energy storage module stores electric energy, and when the line voltage is less than the charging voltage, the energy storage module supplies power to the load;

[0052] S300, the switching power supply module converts the line voltage into low-voltage direct current and outputs it to the load;

[0053] S400: When the energy storage module stores electric energy, the constant current source module adjusts the charging current to control the charging time of the energy storage module.

[0054] The present invention also provides a driving device for suppressing electromagnetic interference, comprising a shell, a PCB board is arranged in the shell, and the driving circuit for suppressing electromagnetic interference as described above is arranged on the PCB board. Since the driving circuit for suppressing electromagnetic interference has been introduced in detail above, it will not be described in detail here.

[0055] In summary, the present invention provides a driving circuit, device and driving method for suppressing electromagnetic interference. The driving circuit for suppressing electromagnetic interference includes a rectifier module, a constant current source module, an energy storage module, a switching power supply module and a load; the input alternating current is rectified by the rectifier module and then outputs a line voltage to the energy storage module and the switching power supply module; the energy storage module is used to store electric energy when the line voltage is greater than the charging voltage of the energy storage module, and to supply power to the switching power supply module and the load when the line voltage is less than the charging voltage; the switching power supply module is used to convert the line voltage into low-voltage direct current and output it to the load; the constant current source module is used to adjust the charging current when the energy storage module stores electric energy, and control the charging time of the energy storage module. Through a simple circuit structure, electromagnetic interference in the circuit is suppressed, harmonic noise in the circuit is reduced, and the power factor is improved.

[0056] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A driving circuit for suppressing electromagnetic interference, characterized in that: It includes a rectifier module, a constant current source module, an energy storage module, a switching power supply module and a load; the input AC power is rectified by the rectifier module and then outputs a line voltage to the energy storage module and the switching power supply module; the energy storage module is used to store electric energy when the line voltage is greater than the charging voltage of the energy storage module, and to supply power to the switching power supply module and the load when the line voltage is less than the charging voltage; the switching power supply module is used to convert the line voltage into low-voltage direct current and output it to the load; the constant current source module is used to adjust the charging current when the energy storage module stores electric energy, and control the charging time of the energy storage module; The switching power supply module includes a first constant voltage chip, a first diode, a first resistor, a second resistor, a first capacitor, a second capacitor and a first inductor. The first pin of the first constant voltage chip is connected to the cathode of the first diode, one end of the first resistor and one end of the first inductor through the second capacitor. The second pin of the first constant voltage chip is connected to the other end of the first resistor and one end of the second resistor. The 8th, 7th, 6th and 5th pins of the first constant voltage chip are all connected to the cathode of the first diode. The anode of the first diode and one end of the first capacitor are grounded. The other end of the first capacitor, the other end of the second resistor and one end of the first inductor are all VDD signal ends. The 4th pin of the first constant voltage chip is connected to the VIN signal end. The constant current source module includes a first operational amplifier, a first MOS tube and a fourth resistor. The drain of the first MOS tube is connected to the rectifier module, the source of the first MOS tube is connected to the inverting input end of the first operational amplifier and one end of the fourth resistor, the other end of the fourth resistor is connected to the energy storage module, the switching power supply module and the input end of the load, and the gate of the first MOS tube is connected to the output end of the first operational amplifier. When the line voltage is greater than the charging voltage of the energy storage module, the charging current of the energy storage module is controlled by the constant current source module to charge the energy storage module to store electric energy; when the line voltage is less than the charging voltage of the energy storage module, the energy storage module discharges the switching power supply module; during the charging process of the energy storage module, the current passing through the rectifier module is the current set by the constant current source module, and the constant current source module adjusts the charging current of the energy storage module to slow down by setting the current, and the charging time of the energy storage module becomes longer; and during the discharging process of the energy storage module, no current flows through the rectifier module; The energy storage module includes a fourth capacitor, one end of the fourth capacitor is connected to the other end of the fourth resistor, and the other end of the fourth capacitor is grounded; The load includes a third diode, an LED light string, a dimmer, a third operational amplifier, a third MOS tube and a sixth resistor; the anode of the third diode is connected to one end of the fourth capacitor, the other end of the fourth resistor and the fourth pin of the first constant voltage chip; the cathode of the third diode is connected to the input end of the LED light string, the drain of the third MOS tube is connected to the output end of the LED light string, the source of the third MOS tube is connected to one end of the sixth resistor and the inverting input end of the third operational amplifier, the output end of the third operational amplifier is connected to the gate of the third MOS tube, the non-inverting input end of the third operational amplifier is connected to the third pin of the dimmer, the second pin of the dimmer is grounded, and the first pin of the dimmer is connected to the switching power supply module; When the switching power supply module enters the working state, it provides low-voltage direct current for the dimmer, so that the dimmer outputs a dimming signal to the non-phase input terminal of the third operational amplifier, and the third operational amplifier adjusts the working current of the LED light string according to the dimming signal; the non-phase input terminal of the first operational amplifier is connected to the reference voltage input terminal to obtain a reference voltage, and the reference voltage is controlled by the dimming signal output by the dimmer. Specifically, as the working current of the LED light string decreases, the charging current of the fourth capacitor decreases accordingly.

2. A driving method for the driving circuit for suppressing electromagnetic interference according to claim 1, characterized in that: The steps include: The input AC power is rectified by the rectifier module and then outputs the line voltage to the energy storage module and the switching power supply module; When the line voltage is greater than the charging voltage of the energy storage module, the energy storage module stores electric energy, and when the line voltage is less than the charging voltage, the energy storage module supplies power to the load; The switching power supply module converts the line voltage into low-voltage direct current and outputs it to the load; When the energy storage module stores electric energy, the constant current source module adjusts the charging current so that the charging time of the energy storage module is increased.

3. A driving device for suppressing electromagnetic interference, comprising a housing, wherein a PCB board is arranged in the housing, characterized in that: The PCB board is provided with the driving circuit for suppressing electromagnetic interference as claimed in claim 1.

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