Multi-path grading harmonic wave improving and dimming circuit

Abstract

The invention provides a multi-path graded harmonic improving and dimming circuit. The multi-path graded harmonic improving and dimming circuit comprises a two-stage filter circuit, a bridge rectifier circuit, a suppression circuit, a power factor correction circuit, a first power supply circuit, a second power supply circuit and a power supply chip, the input end of the two-stage filter circuit is used for being connected with an AC port, the output end of the two-stage filter circuit is connected with the input end of the bridge rectifier circuit, the output end of the bridge rectifier circuit is connected with the input end of the suppression circuit, the output end of the suppression circuit is connected with the input end of the power factor correction circuit, and the output end of the power factor correction circuit is used for being connected with a load. The first power circuit is connected with the suppression circuit and used for providing power for the suppression circuit; and the second power supply circuit is connected with the power factor correction circuit and is used for supplying power to the power factor correction circuit. The multi-path grading harmonic wave improving and dimming circuit is low in cost, small in occupied space and low in overall power consumption.

Description

Technical Field

[0001] The invention relates to the technical field of harmonic circuits, and in particular to a multi-channel graded harmonic improvement and dimming circuit. Background Art

[0002] Harmonic current is also a general term for sinusoidal components whose frequencies are integer multiples of the original periodic current frequency. When the non-sinusoidal periodic current function is expanded according to the Fourier series, the sinusoidal components whose frequencies are integer multiples of the original periodic current frequency are collectively referred to as harmonic currents. Harmonic currents with a frequency equal to k times the original periodic current frequency are called kth harmonic currents, and harmonic currents with k greater than 1 are also collectively referred to as higher-order harmonic currents.

[0003] In the actual process of electricity use, harmonics can reduce the efficiency of electricity production, transmission and utilization, cause electrical equipment to overheat, generate vibration and noise, and age the insulation, shorten the service life, and even cause failure or burnout. Therefore, there are strict national standards for harmonics.

[0004] The current way to solve harmonic current is to add a power factor correction circuit at the input end, which can change the input characteristics of the circuit and make the current output by the power supply more stable. However, this method is costly and occupies a large space. When there are multiple outputs, it is particularly important to design a low-cost multi-channel graded harmonic improvement circuit. Summary of the invention

[0005] The present invention provides a multi-channel graded harmonic improvement and dimming circuit, aiming to solve the problems of high cost, large occupied space and high power consumption of the existing dimming circuit.

[0006] An embodiment of the present invention provides a multi-channel graded harmonic improvement and dimming circuit, comprising: a two-stage filtering circuit, a rectifier bridge stack circuit, a suppression circuit, a power factor correction circuit, a first power supply circuit, a second power supply circuit and a power supply chip; the input end of the two-stage filtering circuit is used to connect to an AC port, the output end of the two-stage filtering circuit is connected to the input end of the rectifier bridge stack circuit, the output end of the rectifier bridge stack circuit is connected to the input end of the suppression circuit, the output end of the suppression circuit is connected to the input end of the power factor correction circuit, and the output end of the power factor correction circuit is used to connect to a load; the first power supply circuit is connected to the suppression circuit to provide power for the suppression circuit; the second power supply circuit is connected to the power factor correction circuit to provide power for the power factor correction circuit.

[0007] Preferably, the two-stage filtering circuit includes a protection circuit, a first-stage filtering circuit and a second-stage filtering circuit;

[0008] The input end of the protection circuit is connected to the AC end, the input end of the first-stage filter circuit is connected to the output end of the protection circuit, the output end of the first-stage filter circuit is connected to the input end of the second-stage filter circuit, and the output end of the second-stage filter circuit is connected to the input end of the rectifier bridge stack circuit.

[0009] Preferably, the protection circuit includes a fuse FUSE1, a variable resistor VR1, a safety capacitor CX1, a resistor R63, a resistor R64, a resistor R56 and a resistor R57;

[0010] The first end of the fuse FUSE1 is connected to the AC port, and the second end of the fuse FUSE1 is respectively connected to the first end of the variable resistor VR1, the first end of the safety capacitor CX1, the first end of the resistor R64, and the first end of the resistor R57; the second end of the resistor R64 is respectively connected to the first end of the resistor R63, the second end of the resistor R57, and the first end of the resistor R56; the second end of the variable resistor VR1 is respectively connected to the second end of the safety capacitor CX1, the second end of the resistor R63, and the second end of the resistor R56.

[0011] Preferably, the first-stage filter circuit includes a differential-mode inductor LF1 and a safety capacitor CX2; the second-stage filter circuit includes a differential-mode inductor LF2 and a safety capacitor CX3;

[0012] The first end of the differential mode inductor LF1 is connected to the second end of the resistor R56, the second end of the differential mode inductor LF1 is connected to the first end of the resistor R57, the third end of the differential mode inductor LF1 is connected to the first end of the safety capacitor CX2, and the fourth end of the differential mode inductor LF1 is connected to the second end of the safety capacitor CX2;

[0013] The first end of the differential mode inductor LF2 is connected to the first end of the safety capacitor CX2, the second end of the differential mode inductor LF2 is connected to the second end of the safety capacitor CX2, the third end of the differential mode inductor LF2 is connected to the first end of the rectifier bridge stack circuit, and the fourth end of the differential mode inductor LF2 is connected to the second end of the rectifier bridge stack circuit; the third and fourth ends of the rectifier bridge stack circuit serve as the output ends of the rectifier bridge stack circuit.

[0014] Preferably, the suppression circuit includes: a capacitor C2, a diode D4, a thermistor NTC1, a capacitor EC1, a capacitor C1, a resistor R1 and an inductor L1;

[0015] The first end of the capacitor C2 is connected to the third end of the rectifier bridge stack circuit, and the second end of the capacitor C2 is connected to the fourth end of the rectifier bridge stack circuit;

[0016] The first end of the capacitor C2 is also respectively connected to the positive electrode of the diode D4, one end of the inductor L1 and the first end of the resistor R91, the negative electrode of the diode D4 is connected to the first end of the thermistor NTC1, and the second end of the thermistor NTC1 is respectively connected to the positive electrode of the capacitor EC1 and the first power supply circuit; the negative electrode of the capacitor EC1 is respectively connected to the second end of the capacitor C2 and the first end of the capacitor C1, and the second end of the capacitor C1 is respectively connected to the second end of the resistor R91 and the second end of the inductor L1.

[0017] Preferably, the power factor correction circuit includes an input matching unit, a control unit and a protection unit; the input end of the input matching unit is connected to the output end of the suppression circuit, the output end of the input matching unit is connected to the input end of the control unit, the output end of the control unit is connected to the input end of the protection unit, the input end of the protection unit is used to connect to a load, and the second power supply circuit is used to power the protection unit.

[0018] Preferably, the input matching unit includes a transformer T1 and a resistor R10; the first end of the transformer T1 is connected to the first end of the capacitor C1, the second end of the transformer T1 is connected to the second end of the capacitor C1, the third end of the transformer T1 is connected to the first end of the resistor R10, and the second end of the resistor R10 is connected to the ZCD detection port; the fourth end of the transformer T1 serves as the output end of the input matching unit.

[0019] Preferably, the control unit includes: a capacitor C6, a resistor R24, a resistor R15, a capacitor C15, a resistor R20, a transistor Q2, a resistor R16, a resistor R14, a resistor R12 and a diode D6;

[0020] The first end of the capacitor C6 is respectively connected to the fourth end of the transformer T1 and the drain of the transistor Q2; the second end of the capacitor C6 is connected to the first end of the resistor R24, the second end of the resistor R24 ​​is connected to the source of the transistor Q2, the source of the transistor Q2 is respectively connected to the first end of the resistor R15 and the first end of the resistor R20, the second end of the resistor R15 is connected to the first end of the capacitor C15, the second end of the capacitor C15 and the second end of the resistor R20 are connected and grounded; the gate of the transistor Q2 is respectively connected to the positive electrode of the diode D6 and the first end of the resistor R16, the second end of the resistor R16 is respectively connected to the negative electrode of the diode D6, the first end of the resistor R14 and the first end of the resistor R12, the second end of the resistor R14 is grounded, and the second end of the resistor R12 is used to connect the PFC-DR port.

[0021] Preferably, the protection unit includes a diode D5, a diode D7, a thermistor NTC2, a capacitor C3, a capacitor C5, a capacitor EC2, a capacitor C9, a resistor R3, a resistor R4, a resistor R5 and a resistor R8;

[0022] The anode of the diode D5 is connected to the first end of the transformer T1, the cathode of the diode D5 is connected to the first end of the resistor R3, the first end of the thermistor NTC2, the first end of the capacitor C5 and the anode of the capacitor EC2, the anode of the diode D7 is connected to the drain of the transistor Q2, the cathode of the diode D7 is respectively connected to the second end of the thermistor NTC2 and the first end of the capacitor C3, the second end of the capacitor C3 is connected to the second end of the capacitor C5 and the cathode of the capacitor EC2 and is grounded; the anode of the capacitor EC2 is used to connect to the second power supply circuit;

[0023] The second end of the resistor R3 is connected to the first end of the resistor R4, the second end of the resistor R4 is connected to the first end of the resistor R5, the second end of the resistor R5 is respectively connected to the first end of the resistor R8 and the first end of the capacitor C9, and the second end of the resistor R8 and the second end of the capacitor C9 are connected and grounded.

[0024] Compared with the prior art, the beneficial effect of the present invention lies in that the input end of the two-stage filter circuit is used to connect to the AC port, the output end of the two-stage filter circuit is connected to the input end of the rectifier bridge stack circuit, the output end of the rectifier bridge stack circuit is connected to the input end of the suppression circuit, the output end of the suppression circuit is connected to the input end of the power factor correction circuit, and the output end of the power factor correction circuit is used to connect to the load; the first power supply circuit is connected to the suppression circuit to provide power for the suppression circuit; the second power supply circuit is connected to the power factor correction circuit to provide power for the power factor correction circuit; so that it has obvious cost advantages in multi-channel output of medium and low power power supply, adopts a multi-channel hierarchical harmonic improvement method, one power supply is suppressed by the pre-stage filter inductor and capacitor for harmonic current, and the other power supply is suppressed by the power factor correction circuit for harmonic current, and the cost is less than the full power factor correction circuit. One power supply works as soon as it is powered on, and the power factor correction circuit and the other power supply provide the chip VCC voltage only after the main control board sends a signal, which greatly reduces the standby power consumption of the power supply itself; the power correction factor circuit does not need to take into account the power of all the power of the subsequent stage, but only part of the power. The components are small in size and low in cost, which can save the space size of the electronic board. At the same time, it can also realize the output constant current dimming function, which allows the main control board to reduce the current after collecting the information that the LED temperature is too high, thereby achieving the cooling function. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be described in detail below in conjunction with the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings. In the accompanying drawings:

[0026] Figure 1 It is a module diagram of a multi-channel graded harmonic improvement and dimming circuit provided by an embodiment of the present invention;

[0027] Figure 2 It is a circuit diagram of a multi-channel graded harmonic improvement and dimming circuit provided by an embodiment of the present invention;

[0028] Figure 3 is a circuit diagram of a power chip provided by an embodiment of the present invention;

[0029] Figure 4 is a circuit diagram of a two-stage filtering circuit provided by an embodiment of the present invention;

[0030] Figure 5 is a circuit diagram of a suppression circuit provided by an embodiment of the present invention;

[0031] Figure 6 A power factor correction circuit is provided in an embodiment of the present invention;

[0032] Figure 7 is a circuit diagram of a first power supply circuit provided by an embodiment of the present invention;

[0033] Figure 8 is a circuit diagram of a second power supply circuit provided by an embodiment of the present invention;

[0034] Fig. 9 is a circuit diagram of a second power switch control circuit provided in an embodiment of the present invention.

[0035] Among them, 1. two-stage filter circuit, 11. protection circuit, 12. first-stage filter circuit, 13. second-stage filter circuit, 2. rectifier bridge circuit, 3. suppression circuit, 4. power factor correction circuit, 41. input matching unit, 42. control unit, 43. protection unit, 5. first power supply circuit, 6. second power supply circuit. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] As attached Figure 1-Figure 9As shown, an embodiment of the present invention provides a multi-channel graded harmonic improvement and dimming circuit, including: a two-stage filter circuit 1, a rectifier bridge circuit 2, a suppression circuit 3, a power factor correction circuit 4, a first power supply circuit 5, a second power supply circuit 6 and a power supply chip U4; the input end of the two-stage filter circuit 1 is used to connect to the AC port, the output end of the two-stage filter circuit 1 is connected to the input end of the rectifier bridge circuit 2, the output end of the rectifier bridge circuit 2 is connected to the input end of the suppression circuit 3, the output end of the suppression circuit 3 is connected to the input end of the power factor correction circuit 4, and the output end of the power factor correction circuit 4 is used to connect to a load PFC-FB; the first power supply circuit 5 is connected to the suppression circuit 3 to provide power for the suppression circuit 3; the second power supply circuit 6 is connected to the power factor correction circuit 4 to provide power for the power factor correction circuit 4. This makes it have obvious cost advantages in the medium and low power power supply with multiple outputs. It adopts a multi-channel hierarchical improvement method. One power supply is suppressed by the pre-stage filter inductor and capacitor to suppress the harmonic current, and the other power supply is suppressed by the power factor correction circuit 4. The cost is lower than the full power factor correction circuit. One power supply works as soon as it is powered on, and the power factor correction circuit 4 and the other power supply provide the chip VCC voltage to work only after the main control board sends a signal, which greatly reduces the standby power consumption of the power supply itself; the power factor correction circuit 4 does not need to take into account the power of all the power of the subsequent power supply, but only part of the power. The components are small in size and low in cost, which can save the space size of the electronic board. At the same time, the output constant current dimming function can be realized, which allows the main control board to reduce the current after collecting the information that the LED temperature is too high, thereby achieving the cooling function.

[0038] The power chip U4 is used to control the first power circuit 5, and the second power circuit 6 is controlled by the second power switch control circuit, thereby achieving a power control effect with high safety.

[0039] Among them, there is no power factor correction circuit 4 in front of the first power supply circuit 5, and a power factor correction circuit 4 is set in front of the second power supply circuit 6; in this way, the first power supply circuit 5 works when it is powered on, and the power factor correction circuit 4 and the second power supply circuit 6 of another circuit provide the chip VCC voltage to work only after the main control board sends a signal, which greatly reduces the standby power consumption of the power supply itself; the power factor correction circuit 4 does not need to take into account the power of all the power of the subsequent stage, but only part of the power, the components are small in size and low in cost, and the space size of the electronic board can be saved. At the same time, the output constant current dimming function can also be realized, which allows the main control board to reduce the current after collecting the information that the LED temperature is too high, thereby achieving the cooling function.

[0040] In this embodiment, the two-stage filter circuit 1 includes a protection circuit 11, a first-stage filter circuit 12 and a second-stage filter circuit 13;

[0041] The input end of the protection circuit 11 is connected to the AC end, the input end of the first-stage filter circuit 12 is connected to the output end of the protection circuit 11, the output end of the first-stage filter circuit 12 is connected to the input end of the second-stage filter circuit 13, and the output end of the second-stage filter circuit 13 is connected to the input end of the rectifier bridge stack circuit 2.

[0042] In this embodiment, the protection circuit 11 includes a fuse FUSE1, a variable resistor VR1, a safety capacitor CX1, a resistor R63, a resistor R64, a resistor R56 and a resistor R57;

[0043] The first end of the fuse FUSE1 is connected to the AC port, and the second end of the fuse FUSE1 is respectively connected to the first end of the variable resistor VR1, the first end of the safety capacitor CX1, the first end of the resistor R64, and the first end of the resistor R57; the second end of the resistor R64 is respectively connected to the first end of the resistor R63, the second end of the resistor R57, and the first end of the resistor R56; the second end of the variable resistor VR1 is respectively connected to the second end of the safety capacitor CX1, the second end of the resistor R63, and the second end of the resistor R56.

[0044] In this embodiment, the first-stage filter circuit 12 includes a differential-mode inductor LF1 and a safety capacitor CX2; the second-stage filter circuit 13 includes a differential-mode inductor LF2 and a safety capacitor CX3;

[0045] The first end of the differential mode inductor LF1 is connected to the second end of the resistor R56, the second end of the differential mode inductor LF1 is connected to the first end of the resistor R57, the third end of the differential mode inductor LF1 is connected to the first end of the safety capacitor CX2, and the fourth end of the differential mode inductor LF1 is connected to the second end of the safety capacitor CX2;

[0046] The first end of the differential mode inductor LF2 is connected to the first end of the safety capacitor CX2, the second end of the differential mode inductor LF2 is connected to the second end of the safety capacitor CX2, the third end of the differential mode inductor LF2 is connected to the first end of the rectifier bridge stack circuit 2, and the fourth end of the differential mode inductor LF2 is connected to the second end of the rectifier bridge stack circuit 2; the third and fourth ends of the rectifier bridge stack circuit 2 serve as the output ends of the rectifier bridge stack circuit.

[0047] In this embodiment, the suppression circuit 3 includes: a capacitor C2, a diode D4, a thermistor NTC1, a capacitor EC1, a capacitor C1, a resistor R1 and an inductor L1;

[0048] The first end of the capacitor C2 is connected to the third end of the rectifier bridge stack circuit 2, and the second end of the capacitor C2 is connected to the fourth end of the rectifier bridge stack circuit 2;

[0049] The first end of the capacitor C2 is also respectively connected to the positive electrode of the diode D4, one end of the inductor L1 and the first end of the resistor R91, the negative electrode of the diode D4 is connected to the first end of the thermistor NTC1, and the second end of the thermistor NTC1 is respectively connected to the positive electrode of the capacitor EC1 and the first power supply circuit 5; the negative electrode of the capacitor EC1 is respectively connected to the second end of the capacitor C2 and the first end of the capacitor C1, and the second end of the capacitor C1 is respectively connected to the second end of the resistor R91 and the second end of the inductor L1.

[0050] In this embodiment, the power factor correction circuit 4 includes an input matching unit 41, a control unit 42 and a protection unit 43; the input end of the input matching unit 41 is connected to the output end of the suppression circuit 3, the output end of the input matching unit 41 is connected to the input end of the control unit 42, the output end of the control unit 42 is connected to the input end of the protection unit 43, the input end of the protection unit 43 is used to connect the load, and the second power supply circuit 6 is used to power the protection unit 43.

[0051] In this embodiment, the input matching unit 41 includes a transformer T1 and a resistor R10; the first end of the transformer T1 is connected to the first end of the capacitor C1, the second end of the transformer T1 is connected to the second end of the capacitor C1, the third end of the transformer T1 is connected to the first end of the resistor R10, and the second end of the resistor R10 is connected to the ZCD detection port; the fourth end of the transformer T1 serves as the output end of the input matching unit 41.

[0052] In this embodiment, the control unit 42 includes: a capacitor C6, a resistor R24, a resistor R15, a capacitor C15, a resistor R20, a transistor Q2, a resistor R16, a resistor R14, a resistor R12 and a diode D6;

[0053] The first end of the capacitor C6 is respectively connected to the fourth end of the transformer T1 and the drain of the transistor Q2; the second end of the capacitor C6 is connected to the first end of the resistor R24, the second end of the resistor R24 ​​is connected to the source of the transistor Q2, the source of the transistor Q2 is respectively connected to the first end of the resistor R15 and the first end of the resistor R20, the second end of the resistor R15 is connected to the first end of the capacitor C15, the second end of the capacitor C15 and the second end of the resistor R20 are connected and grounded; the gate of the transistor Q2 is respectively connected to the positive electrode of the diode D6 and the first end of the resistor R16, the second end of the resistor R16 is respectively connected to the negative electrode of the diode D6, the first end of the resistor R14 and the first end of the resistor R12, the second end of the resistor R14 is grounded, and the second end of the resistor R12 is used to connect the PFC-DR port.

[0054] In this embodiment, the protection unit 43 includes a diode D5, a diode D7, a thermistor NTC2, a capacitor C3, a capacitor C5, a capacitor EC2, a capacitor C9, a resistor R3, a resistor R4, a resistor R5 and a resistor R8;

[0055] The anode of the diode D5 is connected to the first end of the transformer T1, the cathode of the diode D5 is connected to the first end of the resistor R3, the first end of the thermistor NTC2, the first end of the capacitor C5 and the anode of the capacitor EC2, the anode of the diode D7 is connected to the drain of the transistor Q2, the cathode of the diode D7 is respectively connected to the second end of the thermistor NTC2 and the first end of the capacitor C3, the second end of the capacitor C3 is connected to the second end of the capacitor C5 and the cathode of the capacitor EC2 and is grounded; the anode of the capacitor EC2 is used to connect to the second power supply circuit 6;

[0056] The second end of the resistor R3 is connected to the first end of the resistor R4, the second end of the resistor R4 is connected to the first end of the resistor R5, the second end of the resistor R5 is respectively connected to the first end of the resistor R8 and the first end of the capacitor C9, and the second end of the resistor R8 and the second end of the capacitor C9 are connected and grounded.

[0057] In specific implementation, the two-stage filter circuit 1 is composed of safety capacitor CX1, safety capacitor CX2, safety capacitor CX3, differential mode inductor LF1, differential mode inductor LF2, and the varistor VR1 is used to absorb surge voltage to protect the subsequent circuit. Resistors R56 / R57 / R63 / R64 are mainly used to absorb the voltage on the safety capacitor to prevent electric shock after the human body touches the plug.

[0058] After the filter circuit, the AC power enters the rectifier bridge DB1, and the rectified output DC power enters the harmonic current suppression circuit 3 composed of filter capacitor C1, filter capacitor C2, capacitor EC1, capacitor EC2, and filter inductor L1. The phase difference between the fundamental current and voltage of the AC input is reduced, thereby achieving the effect of suppressing harmonic current.

[0059] Capacitor EC1 and capacitor EC2 are filter capacitors, which stabilize the pulse DC voltage rectified by the rectifier bridge BD1 and filter the AC component to the ground line.

[0060] The inductor L1 is connected in parallel with the resistor R91, which forms a damped oscillation with the parasitic capacitance on the inductor L1, which is more effective in suppressing multiple harmonic currents. The resistor R91 is usually selected to be 1-100KΩ.

[0061] The current flows from the rectifier bridge through the diode D4, thermistor NTC1, and capacitor EC1. The first power bus connection terminal HV1 is located at the connection between thermistor NTC1 and capacitor EC1. Thermistor NTC1 can effectively suppress the instantaneous surge current at startup and protect the first power supply from the surge current impact.

[0062] The current flows through the inductor L1 and enters the power factor correction circuit 4. The transistor Q2 is the switch tube of the power factor correction circuit 4. The diode D5 is the freewheeling diode of the power factor correction circuit 4, which is used to charge the capacitor EC2 when starting up to prevent the PFC transformer T1 from being saturated due to excessive charging current. When the power factor correction circuit 4 operates normally, the cathode of the diode has a higher voltage than the anode, and the diode loses its function.

[0063] The power chip U4 is a control chip for the power factor correction circuit 4, wherein pin 7 is a driving pin for issuing a PWM drive switch tube Q2.

[0064] By locating the bus connection terminal HV2 of the second power supply circuit 6 at the connection between the thermistor NTC2 and the capacitor EC2, the thermistor NTC2 can effectively suppress the instantaneous surge current at startup, thereby protecting the first power supply from the surge current impact.

[0065] Because the connection terminal HV2 of the second power supply circuit 6 is after the power factor correction circuit 4, the current harmonic suppression effect is large. With this circuit connection method, the power of the power factor correction circuit 4 only needs to adapt to the power of the second power supply, and does not need to take into account the first power supply, which can achieve low power and low cost, and can be applied to multiple power supplies above 100W.

[0066] The first power source power P1 is within 100W, and the second power source power P2 has no limit on the range. When the second power source power P2 is within 2 times of the first power source power P1, the cost is optimal.

[0067] The first power supply is generally used to output to the main control board, fan motor and other loads, and the second power supply is generally used to output to LED or resistive loads. In order to accurately control the load switch of the second power supply and achieve low standby power consumption, the first power supply is set to be powered on, that is, in working state, to provide voltage to the main control board. When the first power supply is just powered on, the working voltage of the power supply chip U1 is obtained by dividing the voltage of the first power supply bus connection section HV1 by the R1 / R2 / R7 resistors to obtain the VCC connection terminal voltage. After the first power supply enters the steady state, the output of the primary auxiliary winding 6-4 of the first power supply T3 is mainly rectified and filtered by RL1 / R27 / D9 / EC3 / C17 to obtain the power input terminal VCC of the first power supply chip U1.

[0068] CN5 is the connection terminal between the power board and the main control board. When the working signal BL of the second power supply and the power factor correction circuit 4 is at a high level, the transistor Q8 is driven by the resistor R18 to pull down the 2nd pin of the optocoupler U7 to conduct. Thus, the 3rd and 4th pins of the optocoupler U7 are turned on, so that the voltage at the VCC connection end is rectified by the diode D12 and divided by R35 and R40, so that the base of the transistor Q4 is at a high level. The voltage at the VCC connection end is rectified by the diode D12 and filtered by the filter capacitor EC4 / C22, and then supplied to the power input pin of the power factor correction circuit 4 power chip U4 and the power input pin of the second power supply circuit 6 chip U2. At this time, the power factor correction circuit 4 and the second power supply circuit 6 work normally.

[0069] When the second power supply and the power factor circuit working signal BL are at a low level, the power factor correction circuit 4 power chip U4 and the second power chip U2 have no working voltage and stop working.

[0070] When the dimming signal PWM is filtered by capacitor C37, it passes through resistor R82, diode D15, resistor R61 and is superimposed with the sampling signal after the output sampling resistor and flows into the current control input port Vsen of the constant current and constant voltage chip U3.

[0071] The constant current and constant voltage chip U3 receives different PWM dimming signals, and the corresponding feedback signal outputted by Vout enters the FB pin of the second power chip U2 through the optocoupler U5, thereby realizing the dimming function.

[0072] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of more restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, article or device including the element.

[0073] The embodiments of the present invention are described above in conjunction with the accompanying drawings. What is disclosed is only the preferred embodiment of the present invention. However, the present invention is not limited to the above-mentioned specific implementation manner. The above-mentioned specific implementation manner is only illustrative rather than restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms and equivalent changes without departing from the scope of protection of the purpose of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A multi-channel graded harmonic improvement and dimming circuit, characterized in that: include: Two-stage filter circuit, rectifier bridge circuit, suppression circuit, power factor correction circuit, first power supply circuit, second power supply circuit and power supply chip; The input end of the two-stage filter circuit is used to connect to the AC port, the output end of the two-stage filter circuit is connected to the input end of the rectifier bridge stack circuit, the output end of the rectifier bridge stack circuit is connected to the input end of the suppression circuit, the output end of the suppression circuit is connected to the input end of the power factor correction circuit, and the output end of the power factor correction circuit is used to connect to a load; the first power supply circuit is connected to the suppression circuit to provide power for the suppression circuit; The second power supply circuit is connected to the power factor correction circuit and is used to provide power for the power factor correction circuit.

2. The multi-channel graded harmonic improvement and dimming circuit as claimed in claim 1, characterized in that: The two-stage filtering circuit includes a protection circuit, a first-stage filtering circuit and a second-stage filtering circuit; The input end of the protection circuit is connected to the AC end, the input end of the first-stage filter circuit is connected to the output end of the protection circuit, the output end of the first-stage filter circuit is connected to the input end of the second-stage filter circuit, and the output end of the second-stage filter circuit is connected to the input end of the rectifier bridge stack circuit.

3. The multi-channel graded harmonic improvement and dimming circuit as claimed in claim 2, characterized in that: The protection circuit includes a fuse FUSE1, a variable resistor VR1, a safety capacitor CX1, a resistor R63, a resistor R64, a resistor R56 and a resistor R57; The first end of the fuse FUSE1 is connected to the AC port, and the second end of the fuse FUSE1 is respectively connected to the first end of the variable resistor VR1, the first end of the safety capacitor CX1, the first end of the resistor R64, and the first end of the resistor R57; the second end of the resistor R64 is respectively connected to the first end of the resistor R63, the second end of the resistor R57, and the first end of the resistor R56; the second end of the variable resistor VR1 is respectively connected to the second end of the safety capacitor CX1, the second end of the resistor R63, and the second end of the resistor R56.

4. The multi-channel graded harmonic improvement and dimming circuit as claimed in claim 3, characterized in that: The first-stage filter circuit includes a differential-mode inductor LF1 and a safety capacitor CX2; the second-stage filter circuit includes a differential-mode inductor LF2 and a safety capacitor CX3; The first end of the differential mode inductor LF1 is connected to the second end of the resistor R56, the second end of the differential mode inductor LF1 is connected to the first end of the resistor R57, the third end of the differential mode inductor LF1 is connected to the first end of the safety capacitor CX2, and the fourth end of the differential mode inductor LF1 is connected to the second end of the safety capacitor CX2; The first end of the differential mode inductor LF2 is connected to the first end of the safety capacitor CX2, the second end of the differential mode inductor LF2 is connected to the second end of the safety capacitor CX2, the third end of the differential mode inductor LF2 is connected to the first end of the rectifier bridge stack circuit, and the fourth end of the differential mode inductor LF2 is connected to the second end of the rectifier bridge stack circuit; the third and fourth ends of the rectifier bridge stack circuit serve as the output ends of the rectifier bridge stack circuit.

5. The multi-channel graded harmonic improvement and dimming circuit as claimed in claim 4, characterized in that: The suppression circuit includes: capacitor C2, diode D4, thermistor NTC1, capacitor EC1, capacitor C1, resistor R1 and inductor L1; The first end of the capacitor C2 is connected to the third end of the rectifier bridge stack circuit, and the second end of the capacitor C2 is connected to the fourth end of the rectifier bridge stack circuit; The first end of the capacitor C2 is also respectively connected to the positive electrode of the diode D4, one end of the inductor L1 and the first end of the resistor R91, the negative electrode of the diode D4 is connected to the first end of the thermistor NTC1, and the second end of the thermistor NTC1 is respectively connected to the positive electrode of the capacitor EC1 and the first power supply circuit; the negative electrode of the capacitor EC1 is respectively connected to the second end of the capacitor C2 and the first end of the capacitor C1, and the second end of the capacitor C1 is respectively connected to the second end of the resistor R91 and the second end of the inductor L1.

6. The multi-channel graded harmonic improvement and dimming circuit as claimed in claim 5, characterized in that: The power factor correction circuit includes an input matching unit, a control unit and a protection unit; the input end of the input matching unit is connected to the output end of the suppression circuit, the output end of the input matching unit is connected to the input end of the control unit, the output end of the control unit is connected to the input end of the protection unit, the input end of the protection unit is used to connect to a load, and the second power supply circuit is used to power the protection unit.

7. The multi-channel graded harmonic improvement and dimming circuit as claimed in claim 6, characterized in that: The input matching unit includes a transformer T1 and a resistor R10; the first end of the transformer T1 is connected to the first end of the capacitor C1, the second end of the transformer T1 is connected to the second end of the capacitor C1, the third end of the transformer T1 is connected to the first end of the resistor R10, and the second end of the resistor R10 is connected to the ZCD detection port; the fourth end of the transformer T1 serves as the output end of the input matching unit.

8. The multi-channel graded harmonic improvement and dimming circuit as claimed in claim 7, characterized in that: The control unit includes: a capacitor C6, a resistor R24, a resistor R15, a capacitor C15, a resistor R20, a transistor Q2, a resistor R16, a resistor R14, a resistor R12 and a diode D6; The first end of the capacitor C6 is respectively connected to the fourth end of the transformer T1 and the drain of the transistor Q2; the second end of the capacitor C6 is connected to the first end of the resistor R24, the second end of the resistor R24 ​​is connected to the source of the transistor Q2, the source of the transistor Q2 is respectively connected to the first end of the resistor R15 and the first end of the resistor R20, the second end of the resistor R15 is connected to the first end of the capacitor C15, the second end of the capacitor C15 and the second end of the resistor R20 are connected and grounded; the gate of the transistor Q2 is respectively connected to the positive electrode of the diode D6 and the first end of the resistor R16, the second end of the resistor R16 is respectively connected to the negative electrode of the diode D6, the first end of the resistor R14 and the first end of the resistor R12, the second end of the resistor R14 is grounded, and the second end of the resistor R12 is used to connect the PFC-DR port.

9. The multi-channel graded harmonic improvement and dimming circuit as claimed in claim 8, characterized in that: The protection unit includes a diode D5, a diode D7, a thermistor NTC2, a capacitor C3, a capacitor C5, a capacitor EC2, a capacitor C9, a resistor R3, a resistor R4, a resistor R5 and a resistor R8; The anode of the diode D5 is connected to the first end of the transformer T1, the cathode of the diode D5 is connected to the first end of the resistor R3, the first end of the thermistor NTC2, the first end of the capacitor C5 and the anode of the capacitor EC2, the anode of the diode D7 is connected to the drain of the transistor Q2, the cathode of the diode D7 is respectively connected to the second end of the thermistor NTC2 and the first end of the capacitor C3, the second end of the capacitor C3 is connected to the second end of the capacitor C5 and the cathode of the capacitor EC2 and is grounded; the anode of the capacitor EC2 is used to connect to the second power supply circuit; The second end of the resistor R3 is connected to the first end of the resistor R4, the second end of the resistor R4 is connected to the first end of the resistor R5, the second end of the resistor R5 is respectively connected to the first end of the resistor R8 and the first end of the capacitor C9, and the second end of the resistor R8 and the second end of the capacitor C9 are connected and grounded.

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